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Sample records for pleistocene environmental change

  1. Hominin responses to environmental changes during the Middle Pleistocene in Central and Southern Italy

    NASA Astrophysics Data System (ADS)

    Orain, R.; Lebreton, V.; Russo Ermolli, E.; Sémah, A.-M.; Nomade, S.; Shao, Q.; Bahain, J.-J.; Thun Hohenstein, U.; Peretto, C.

    2012-10-01

    Pleistocene. This could have constrained human groups to migrate into such a propitious area. Regarding to the local climate evolution during the glacial episodes, the supposed displacement from these sites could be linked to the environmental dynamics solely due to the aridity increase rather than directly to the global climate changes.

  2. Hominin responses to environmental changes during the Middle Pleistocene in central and southern Italy

    NASA Astrophysics Data System (ADS)

    Orain, R.; Lebreton, V.; Russo Ermolli, E.; Sémah, A.-M.; Nomade, S.; Shao, Q.; Bahain, J.-J.; Thun Hohenstein, U.; Peretto, C.

    2013-03-01

    Pleistocene. This could have constrained human groups to migrate into such a propitious area. Regarding the local climate evolution during the glacial episodes, the supposed displacement from these sites could be linked to the environmental dynamics solely due to the aridity increase, rather than directly to the global climate changes.

  3. Effects of Pleistocene environmental changes on the distribution and community structure of the mammalian fauna of Mexico

    NASA Astrophysics Data System (ADS)

    Ceballos, Gerardo; Arroyo-Cabrales, Joaquín; Ponce, Eduardo

    2010-05-01

    Biological communities in Mexico experienced profound changes in species composition and structure as a consequence of the environmental fluctuations during the Pleistocene. Based on the recent and fossil Mexican mammal checklists, we determine the distribution, composition, diversity, and community structure of late Pleistocene mammalian faunas, and analyze extinction patterns and response of individual species to environmental changes. We conclude that (1) differential extinctions occurred at family, genus, and species level, with a major impact on species heavier than 100 kg, including the extinction all proboscideans and several ruminants; (2) Pleistocene mammal communities in Mexico were more diverse than recent ones; and (3) the current assemblages of species are relatively young. Furthermore, Pleistocene relicts support the presence of biogeographic corridors; important refugia existed as well as centers of speciation in isolated regions. We identified seven corridors: eastern USA-Sierra Madre Oriental corridor, Rocky Mountains-Sierra Madre Occidental corridor, Central United States-Northern Mexico corridor, Transvolcanic Belt-Sierra Madre del Sur corridor, western USA-Baja California corridor, Tamaulipas-Central America gulf lowlands corridor, and Sonora-Central America Pacific lowlands corridor. Our study suggests that present mammalian assemblages are very different than the ones in the late Pleistocene.

  4. The relationship between environmental change and the extinction of the nannoplankton Discoaster in the early Pleistocene

    NASA Astrophysics Data System (ADS)

    Schueth, Jonathan D.; Bralower, Timothy J.

    2015-07-01

    The long-ranging nannoplankton genus Discoaster went extinct in the early Pleistocene, one of the most significant events in the Cenozoic nannofossil record. The causal factors of this extinction are poorly constrained, at least partially because the ecology of Discoaster is not well understood. We investigate the relationship between the extinction and environmental changes by comparing a suite of high-resolution nannofossil assemblage data at four Ocean Drilling Program sites to published environmental proxy records. Through the use of multivariate analysis, we determine Discoaster shared environmental preferences with the extant species Florisphaera profunda which thrives in the lower photic zone near the nutricline in locations where the water column is stratified. We show that the last occurrence of Discoaster was globally diachronous, rather than synchronous as previously thought, and likely took place in the equatorial Atlantic Ocean. We propose that the demise of Discoaster was a two-stage process. A decrease in sea surface temperatures and increase in climate variability led to a global decline in Discoaster abundance. The extinction event itself correlates to shoaling of the nutricline as signified by a decrease in the carbon isotopic gradient between surface and thermocline foraminifera. We hypothesize that the combination of global cooling and a shoaling of the nutricline greatly reduced Discoaster's deepwater niche and contributed to its extinction. This may suggest that ocean stratification and the depth of the nutricline are important contributors to overall nannoplankton diversity.

  5. Environmental, depositional and cultural changes in the upper Pleistocene and early Holocene; the Cinglera del Capello Sequence (Capellades, Spain)

    USGS Publications Warehouse

    Vaquero, Manuel; Allue, Ethel; Bischoff, James L.; Burjachs, Francesc; Vallverdu, Josep

    2013-01-01

    The correlation between environmental and cultural changes is one of the primary archeological and paleoanthropological research topics. Analysis of ice and marine cores has yielded a high-resolution record of millennial-scale changes during the Late Pleistocene and Holocene eras. However, cultural changes are documented in low-resolution continental deposits; thus, their correlation with the millennial-scale climatic sequence is often difficult. In this paper, we present a rare occurrence in which a thick archeological sequence is associated with a high-resolution environmental record. The Cinglera del Capello is a tufa-draped cliff located in the northeastern Iberian Peninsula, 50 km west of Barcelona. This cliff harbors several rock-shelters with Late Pleistocene and Early Holocene deposits. Together, the deposits of four rock-shelters span from 7000 to 70,000 years ago and provide a high-resolution record of the environmental and human dynamics during this timespan. This record allows the correlation of the cultural and environmental changes. The multiproxy approach to the Cinglera evidence indicates that the main cultural stages of the Late Pleistocene and Early Holocene (Middle Paleolithic, Upper Paleolithic and Mesolithic) are associated with significant changes in the environmental and depositional contexts.

  6. Pleistocene To Holocene Human, Climatic and Environmental Changes In Central and Eastern Java (indonesia)

    NASA Astrophysics Data System (ADS)

    Sémah, A.-M.; Sémah, F.; Simanjuntak, H. T.

    The period between 21,000 and 6000 BP, which includes the Pleistocene-Holocene boundary, is likely to have known drastic environmental changes in the Indones ian archipelago, as seen from various sedimentary, pollen analytic, and archaeological records. In a low altitude swampy basin of central Java which yielded a thick clay and peat stratigraphy, several steps can be pointed between the driest period noticed prior 15,000 BP up to a climatic optimum c. 8,000 BP: a significant increase in humidity from c. 15,000 BP onwards, an extension of the forest after 10,500 BP, completion of almost everwet conditions c. 8,500 BP before a forest regression at c.6000 BP. Correlative excavations of the cave fillings near the coast of the Indian ocean, in the Southern Mountains of Java island, reflect conspicuous changes in the archaeological record: a more or less occasional human occupation of the caves during the late Plaistocene is followed by an intensive one in the early Holocene. Human groups, who brought new technologies (like sophisticated bone tools) had to adapt to and get their subsistence in an extending rain forest like environment, with a faunal turnover (Macaca and Presbytis dominance) or in the numerous flooded basins which formed during that period (fresh water molluscs gathering and smaller tortoise hunting). They carried out close contacts with the coastal area and used also the caves as burial places.

  7. Multi-proxy evidence for Late Pleistocene-Holocene climatic and environmental changes in Lop-Nur, Xinjiang, Northwest China

    USGS Publications Warehouse

    Luo, C.; Yang, D.; Peng, Z.; Zhang, Z.; Weiguo, L.; He, J.; Zhou, C.

    2008-01-01

    A 10.35-m-long sediment core from the Luobei depression in Lop-Nur, Xinjiang, Northwest China, provides detailed information about environmental changes during the Late Pleistocene. The samples taken every 5 cm of the core were analyzed for 10 environmental proxies, including magnetic susceptibility, granularity, chroma, carbonate and loss on ignition (LOI), and pH value. The chronology data are provided by the uranium/thorium disequilibrium dates. The sediments of the section were deposited during the last 32000 years. The results of analysis of 10 proxies were examined using multivariate statistical analysis, and the principal components were calculated. According to the results, the Late Pleistocene sequence contains four climatic and environmental stages appearing in the cycles of cold-wet and warm-dry changes. During 10-9 ka BP, it was the earliest warm episode in the Holocene. Environmental changes in this district were restricted by global change, as suggested by the analysis of glacial-interglacial cycles. But it was different from the mutative trend of a monsoon region in East China because of its own characteristics, which was the situation of cold-wet and warm-dry climate-environment change. The candidate reason may be the uplift of the Tibet Plateau and the westerly wind circulation. ?? Science Press, Institute of Geochemistry, CAS and Springer-Verlag GmbH 2008.

  8. Terminal Pleistocene/Early Holocene Environmental Change at the Sunshine Locality, North-Central Nevada, U.S.A.

    NASA Astrophysics Data System (ADS)

    Huckleberry, Gary; Beck, Charlotte; Jones, George T.; Holmes, Amy; Cannon, Michael; Livingston, Stephanie; Broughton, Jack M.

    2001-05-01

    Sedimentological, faunal, and archaeological investigations at the Sunshine Locality, Long Valley, Nevada reveal a history of human adaptation and environmental change at the last glacial-interglacial transition in North America's north-central Great Basin. The locality contains a suite of lacustrine, alluvial, and eolian deposits associated with fluvially reworked faunal remains and Paleoindian artifacts. Radiocarbon-dated stratigraphy indicates a history of receding pluvial lake levels followed by alluvial downcutting and subsequent valley filling with marsh-like conditions at the end of the Pleistocene. A period of alluvial deposition and shallow water tables (9,800 to 11,000 14C yr B.P.) correlates to the Younger Dryas. Subsequent drier conditions and reduced surface runoff mark the early Holocene; sand dunes replace wetlands by 8,000 14C yr B.P. The stratigraphy at Sunshine is similar to sites located 400 km south and supports regional climatic synchroneity in the central and southern Great Basin during the terminal Pleistocene/early Holocene. Given regional climate change and recurrent geomorphic settings comparable to Sunshine, we believe that there is a high potential for buried Paleoindian features in primary association with extinct fauna elsewhere in the region yet to be discovered due to limited stratigraphic exposure and consequent low visibility.

  9. Response of the paleomagnetic record to environmental changes in the late Pleistocene

    NASA Astrophysics Data System (ADS)

    Pilipenko, O. V.; Trubikhin, V. M.; Abrahamsen, H.; Buylaert, J.-P.

    2010-12-01

    During revisiting the Upper Pleistocene Pekla loess-soil section located on the Sea of Azov coast of the Taman Peninsula, its lower 6 m were continuously sampled, which led to an increase in the age range from ˜50 to 400 ka. The detailed rock magnetic study of the structure, grain-size, and concentrations of magnetic mineral (natural remanent magnetization (NRM) carrier) in the collected rock samples revealed regular changes in rock magnetic characteristics along the section and their correlation with climatic fluctuations. Magnetite and hematite both deposited during the transport of sedimentary material and formed during pedogenesis, which involved the entire section to a varying extent, represent the main magnetic minerals in the examined rocks. Automorphic paleosoils that were formed during warm and humid periods corresponding to odd stages of the MIS scale are characterized by elevated concentrations of magnetic mineral (NRM, magnetic susceptibility ( K lf), saturation isothermal remanent magnetization (SIRM), and anhysteresis (ideal) remanent magnetization (ARM)) parameters and share of superparamagnetic particles (up to 80%, according to elevated values of the frequency-dependent magnetic susceptibility K td) as well as by lowered rigidity parameter ( B cr) and grain size (ARM/ K parameter). Such changes in the paleosoils may be explained by the occurrence of newly formed fine-grained magnetite particles close in size to its superparamagnetic and single-domain varieties due to the activation of bio/geochemical processes during warm stages. The growth of the above-mentioned rock magnetic parameters in automorphic soils may be considered as serving a quantitative criterion for defining the boundary between warm and cold periods even in poorly developed soils.

  10. Middle Pleistocene to Holocene geochronology of the River Aguas terrace sequence (Iberian Peninsula): Fluvial response to Mediterranean environmental change

    NASA Astrophysics Data System (ADS)

    Schulte, Lothar; Julià, Ramon; Burjachs, Francesc; Hilgers, Alexandra

    2008-06-01

    Our results from the River Aguas basin suggest that fluvial archives, travertine and slope deposits provide sensitive resolution records of environmental changes during the last 170 kyr. From the chronostratigraphic data sets we have established a model of middle and late Pleistocene river response for littoral basins on the southern Iberian Peninsula. U/Th and OSL dating indicate the major periods of travertine formation of the Alfaix travertine platform, which range from 169 to 26 kyr. At least four incision events interrupted this aggradation period: between 167 and 148 kyr, between 148 and 110 kyr, around 95 kyr and at 71 kyr. Aggradation ceased after 26 kyr and incision occurred during OIS 2. Subsequently, the terraces T4a and T4b were deposited. OSL dating of the T4a channel deposit provides maximum ages of 28, 20 and 18 kyr. However, short climatic events, such as the Younger Dryas, produced two more river incision episodes during OIS 2. Nonetheless, for river systems influenced by tectonics, climate and sea-level changes it is difficult to assess the weight of each controlling factor. Regarding the three mechanisms of Pleistocene river dynamics in middle-size catchment areas of the littoral region of southeastern Spain, our results support the hypothesis that large scale tectonics triggered the general downcutting trend, whereas the main aggradation and incision phases occurred during periods of major sea-level changes. Over short-time scales the influence of climate variability, as documented by pollen records, plays a decisive role. Thus, the river responses to the three cyclic mechanisms operate at different time scales although synergetic processes should be considered with respect to the magnitude of abrupt incision/aggradation events.

  11. Tapping the Late Pleistocene-Holocene environmental change and alluvial geoarchaeology in Central Asia

    NASA Astrophysics Data System (ADS)

    Macklin, Mark; Panyushkina, Irina; Toonen, Willem; Chang, Claudia; Seitkaliyev, Meyram; Voyakin, Dmitry

    2015-04-01

    We integrate the environmental history derived from spatial-temporal variability of multi proxies and the prehistory of arid lands from archaeological data in Central Asia in order to determine the relationship between the Holocene river dynamics, climate change and floodwater farming. This study addresses to developing fluvial achieves and geoarcheological records from the Talgar catchment, a south-bank tributary of the Ili River and the Talas catchment, a east-bank tributary of the Syr Darya River, in the southern Kazakhstan. The catchments of these steppe rivers flowing northwest had favorable habitats for farming from the Eneolithic to the medieval period as appears from human settlement histories documented with archaeological surveys and in some cases excavations. The river development has been reconstructed over the last 20,000 years and the key archaeological sites have been dated with radiocarbon. Periods of Holocene river aggradation and high water in downstream Lake Balkhash and Aral Sea correspond with cooler and wetter neoglacial episodes while river entrenchment and floodplain soil development are associated with warmer and drier conditions. Floodwater farming in the Talgar River reached its height in the late Iron Age (400-200 cal. BC) with more than 70 settlement sites and 700 burial mounds, and in the Talas River during the medieval period. This corresponds to a period of reduced flood flows, river stability and glacier retreat in the Tien Shan headwaters. A new hydroclimatic-based model for the spatial and temporal dynamics of floodwater farming is proposed, which explains settlement patterns since the first documented use of irrigation in the Iron Age and medieval times. The undertaken research highlights the Holocene human adaptations to the environmental change of floodplains in Central Asia.

  12. Mitochondrial DNA Indicates Late Pleistocene Divergence of Populations of Heteronympha merope, an Emerging Model in Environmental Change Biology

    PubMed Central

    Pavlova, Alexandra; Bull, James K.; Murray, Neil D.; Sunnucks, Paul

    2009-01-01

    Knowledge of historical changes in species range distribution provides context for investigating adaptive potential and dispersal ability. This is valuable for predicting the potential impact of environmental change on species of interest. Butterflies are one of the most important taxa for studying such impacts, and Heteronympha merope has the potential to provide a particularly valuable model, in part due to the existence of historical data on morphological traits and glycolytic enzyme variation. This study investigates the population genetic structure and phylogeography of H. merope, comparing the relative resolution achieved through partial DNA sequences of two mitochondrial loci, COI and ND5. These data are used to define the relationship between subspecies, showing that the subspecies are reciprocally monophyletic. On this basis, the Western Australian subspecies H. m. duboulayi is genetically distinct from the two eastern subspecies. Throughout the eastern part of the range, levels of migration and the timing of key population splits of potential relevance to climatic adaptation are estimated and indicate Late Pleistocene divergence both of the Tasmanian subspecies and of an isolated northern population from the eastern mainland subspecies H. m. merope. This information is then used to revisit historical data and provides support for the importance of clinal variation in wing characters, as well as evidence for selective pressure acting on allozyme loci phosphoglucose isomerase and phosphoglucomutase in H. merope. The study has thus confirmed the value of H. merope as a model organism for measuring responses to environmental change, offering the opportunity to focus on isolated populations, as well as a latitudinal gradient, and to use historical changes to test the accuracy of predictions for the future. PMID:19956696

  13. Geomorphic and sedimentary responses of the Bull Creek Valley (Southern High Plains, USA) to Pleistocene and Holocene environmental change

    NASA Astrophysics Data System (ADS)

    Arauza, Hanna M.; Simms, Alexander R.; Bement, Leland C.; Carter, Brian J.; Conley, Travis; Woldergauy, Ammanuel; Johnson, William C.; Jaiswal, Priyank

    2016-01-01

    Fluvial geomorphology and stratigraphy often reflect past environmental and climate conditions. This study examines the response of Bull Creek, a small ephemeral creek in the Oklahoma panhandle, to environmental conditions through the late Pleistocene and Holocene. Fluvial terraces were mapped and their stratigraphy and sedimentology documented throughout the course of the main valley. Based on their elevations, terraces were broadly grouped into a late-Pleistocene fill terrace (T3) and two Holocene fill-cut terrace sets (T2 and T1). Terrace systems are marked by similar stratigraphies recording the general environmental conditions of the time. Sedimentary sequences preserved in terrace fills record the transition from a perennial fluvial system during the late glacial period and the Younger Dryas to a semiarid environment dominated by loess accumulation and punctuated by flood events during the middle to late Holocene. The highest rates of aeolian accumulation within the valley occurred during the early to middle Holocene. Our data provide significant new information regarding the late-Pleistocene and Holocene environmental history for this region, located between the well-studied Southern and Central High Plains of North America.

  14. Environmental Influences on Pleistocene Hominid Dental Evolution

    ERIC Educational Resources Information Center

    Greene, David L.

    1970-01-01

    Considers natural and cultural environmental factors likely to have been responsible for reduction in size of hominid teeth and simplification of their morphology during the Pleistocene. Cites fossil evidence and postulates selective mechanisms. (EB)

  15. Multiproxy evidence of Late Pleistocene environmental changes in the loess-paleosol sequence of Bůhzdař (Czech Republic)

    NASA Astrophysics Data System (ADS)

    Flašarová, Kristýna; Vysloužilová, Barbora; Juřičková, Lucie; Šefrna, Luděk; Verecchia, Eric

    2016-04-01

    Loess-paleosol sequences preserve information that can be used to reconstruct paleoenvironement, specifically the climatic conditions and the vegetation present at the time of their formation, or determine their age. A dense network of reliably analyzed sequences from different geographic locations is crucial for representation of ecological and climatic trends during the Pleistocene (Frechen, 2011). The aim of this study is to fill the gap in the geographical distribution of well described loess-paleosol sequences in Central Europe. Therefore, it focuses on a loess-paleosol sequence in Bůhzdař, situated 9 km NW of Prague, Czech Republic. This profile was last studied in 1952 by naturalist Vojen Ložek. This study uses a number of analyses in order to get a multi-proxy record of local paleoenvironmental changes archived in a sequence of alternating loess sediments and paleosols in Bůhzař. Geochemical approaches are combined with paleozoology to define climatic conditions at the time of formation of the strata. Oxygen isotope 18O values of pedogenic carbonates can be used as a proxy of climatic factors such as temperature and precipitation, whereas carbon isotope values can be used to reconstruct changes in the atmospheric CO2 concentration (Obreht et al. 2013), perhaps also the relative proportions of plants using C3 and C4 metabolic pathways (Kaakinen et al., 2006). Findings of fossil malacofauna, which occupied specific ecological niches, can complement these results. The Bůhzdař locality is exceptional in terms of density of pedogenic carbonates, such as loess dolls, pseudomycelia and marl concretions. These concretions are, in some parts, more compact and form a compact layer. Analysis of pedogenic processes could bring new clues regarding the understanding of the way various forms of carbonates were formed. The analyses are in progress and the first results will be presented during an EGU session in April 2016. References Frechen, M. ed. (2011). Loess in

  16. Tepexpan Palaeoindian site, Basin of Mexico: multi-proxy evidence for environmental change during the late Pleistocene-late Holocene

    NASA Astrophysics Data System (ADS)

    Lamb, Angela L.; Gonzalez, Silvia; Huddart, David; Metcalfe, Sarah E.; Vane, Christopher H.; Pike, Alistair W. G.

    2009-09-01

    The Tepexpan Palaeoindian skeleton was discovered in 1947 close to the former Lake Texcoco margin, in the Basin of Mexico. The find has been the object of considerable interest and discussion over the last 60 years regarding its real age and archaeological interpretation. Here we report new AMS radiocarbon dates associated with the sedimentary succession at Tepexpan with ages between 19,110 ± 90 and 612 ± 22 14C years BP and a new uranium-series date for the skeleton with an age of 4700 ± 200 years BP that indicates a mid Holocene age. The sedimentary succession was studied in detail using: stable isotopes, diatoms, organic geochemistry and tephrochronology. The multi-proxy evidence suggests large changes around the margins of Lake Texcoco in terms of the balance between aquatic and terrestrial plants, C 3 and C 4 plants, saline, alkaline and freshwater conditions, volcanic activity, marginal reworking of lake sediments and input from the drainage basin through the late Pleistocene-late Holocene. These changes had large impacts on the prehistoric human populations living by the lake shores since the late Pleistocene in the Basin of Mexico.

  17. Environmental changes in the Ulan Buh Desert, southern Inner Mongolia, China since the middle Pleistocene based on sedimentology, chronology and proxy indexes

    NASA Astrophysics Data System (ADS)

    Li, Guoqiang; Jin, Ming; Chen, Xuemei; Wen, Lijuan; Zhang, Jiawu; Madsen, David; Zhao, Hui; Wang, Xin; Fan, Tianlai; Duan, Yanwu; Liu, Xiaokang; Wu, Duo; Li, Fangliang; Chen, Fahu

    2015-11-01

    The Ulan Buh Desert (UBD), in southwestern Inner Mongolia, is one of the main dune fields and dust source areas in northern China. The formation of the desert and associated environmental changes since the middle Pleistocene are still unclear due to a lack of depositional records and environmental proxy index analyses. In this study, quartz and K-feldspar optical dating, environmental proxy indexes of grain size, loss on ignition, pollen, and ostracod analysis were employed to supplement the sediment record of a 120.5 m drill core, WL12ZK-1, from the southern UBD. In combination with previous stratigraphic records obtained from drill cores WL10ZK-1 (35 m deep) and WL10ZK-2 (32 m deep) from the northern UBD, and drill core WL12ZK-2 (80 m deep) from the northeastern UBD, these proxies indicate there has been essentially an arid environment in the UBD, with desert or steppe vegetation, since the middle Pleistocene, and that sand dunes were widely distributed in the UBD beginning at least ∼230 ka ago. The Yellow River filled a freshwater paleolake beginning ∼15 ka ago that covered both the UBD and the adjacent Hetao Plain. The paleolake lasted until ∼87 ka, and was associated with wetlands along its margins. Steppe vegetation was present in the surrounding region. An arid environment appeared again after ∼87 ka, and there is no evidence of a large stable lake in the UBD at any time thereafter. Sand dune deposition and a very arid desert environment were present throughout the last glacial period and lasted into the early Holocene. During the Holocene these arid conditions were interrupted by minor wetland intervals. Deserts in southern Inner Mongolia formed at least since the middle Pleistocene, expanded during the last glaciation and into the early Holocene and again after ∼2 ka. We suggest that a combination of tectonic activity and climate change may be responsible for desert formation and environmental changes in southern Inner Mongolia since the middle

  18. Late Pleistocene to Holocene environmental changes as recorded in the sulfur geochemistry of coastal plain sediments, southwestern Taiwan

    USGS Publications Warehouse

    Chen, Y.-G.; Liu, J.C.-L.; Shieh, Y.-N.; Liu, T.-K.

    2004-01-01

    A core, drilled at San-liao-wan in the southwestern coastal plain of Taiwan, has been analyzed for total sulfur contents, isotopic values, as well as ratios of pyritic sulfur to organic carbon. Our results demonstrate a close relationship between late Pleistocene sea-level change and the proxies generated in this study. The inorganic sulfur contents indicate that at our study site, the Holocene transgression started at ???11 ka and remained under seawater for thousands of years until the late Holocene, corresponding to a depth of 20 m in the study core. The uppermost 20 m of core shows relatively high total organic carbon (TOC) and ??34S of inorganic sulfur, suggesting a transitional environment such as muddy lagoon or marsh, before the site turned into a modern coastal plain. In the lower part of the core, at depths of 110-145 m (corresponding ages of ???12-30 ka), low sulfur contents are recorded, probably indicating fluvial sediments deposited during the oceanic isotope stage (OIS) 2, a sea-level lowstand. The lower part of the core, roughly within OIS 3, records at least two transgressions, although the transgressional signals may be somewhat obscured by subsequent weathering. The reworked origin of organic matter reported in previous studies is confirmed by our organic sulfur data; however, the marine organic source was periodically dominant. The modern high sulfate concentrations in pore water have no correlation to the other sulfur species in the sediments, probably indicating that the sulfate migrated into the site subsequent to early diagenesis. ?? 2003 Elsevier Ltd. All rights reserved.

  19. Orbital-driven environmental changes recorded at ODP Site 959 (eastern equatorial Atlantic) from the Late Miocene to the Early Pleistocene

    NASA Astrophysics Data System (ADS)

    Vallé, Francesca; Westerhold, Thomas; Dupont, Lydie M.

    2016-06-01

    Palaeorecords from tropical environments are important to explore the linkages between precipitation, atmospheric circulation and orbital forcing. In this study, new high-resolution XRF data from ODP Site 959 (3°37'N, 2°44'W) have been used to investigate the relationship between palaeoenvironmental changes in West Africa and sedimentation in the tropical East Atlantic Ocean. Iron intensity data have been used to build a 91-m composite depth record that has been astronomically tuned allowing the development of a detailed age model from 6.2 to 1.8 Ma. Based on this new stratigraphy, we studied the variations of Ti/Al, Ti/Ca and Al/Si ratios, proxies for aeolian versus fluvial supply, as dust indicator and fine versus coarse grain size, respectively. We discuss sedimentation patterns at ODP Site 959 associated with the environmental changes from the late Miocene until the early Pleistocene. During the interval corresponding to the earlier stages of the Messinian Salinity Crisis, our proxy records indicate enhanced run-off from the West African continent and major supply of fine material at ODP Site 959, suggesting a stronger monsoon and increased precipitation during eccentricity minima. A long-term decrease of river supply is documented after 5.4 Ma until the end of the Pliocene. From the increased values and variability of Ti/Al and Ti/Ca ratios, we suggest that after 3.5 Ma dust started to reach the study site probably as a result of the southward shift of the Intertropical Convergence Zone during winter. Between 3.2 and 2.9 Ma, ODP Site 959 Ti/Ca ratios exhibit three maxima corresponding to eccentricity maxima similarly to other dust records of northern Africa. This suggests continent-wide aridity or larger climate variability during that interval. Eccentricity forcing (405 and 100 kyr) and precession frequencies are found in the entire studied interval. The variations of Ti/Al ratio suggest stronger seasonality between 5.8 and 5.5 Ma and after 3.2 Ma.

  20. Environmental reconstruction and biostratigraphy of late Middle Pleistocene lakeshore deposits at Schöningen.

    PubMed

    Urban, Brigitte; Bigga, Gerlinde

    2015-12-01

    The Pleistocene sequence of Schöningen provides a key link between unglaciated and glaciated areas in western Central Europe and is an important point of reference for the subdivision of the glaciated late Middle Pleistocene. This locality yields paleoecological and geological evidence of at least four interglacial periods prior to the Holocene and younger than the Elsterian glaciation. The Pleistocene deposits at Schöningen are valuable archives of climate, landscape, and human evolution, containing outstanding information on past environmental changes and human adaptation. This paper presents paleoenvironmental and biostratigraphical results from the Middle Pleistocene archaeological lakeshore site of Schöningen, focusing on the so-called reference profile Schöningen 13 II of 2003. We discuss the lithological, palynological, and macrobotanical evidence and present a revised subdivision and reinterpretation of late phases of the Reinsdorf Interglacial.

  1. Changing environmental conditions during a geomagnetic reversal: Evidence from trace element and isotope variations on Pleistocene flowstone sequences from Cueva Victoria (SE Spain)

    NASA Astrophysics Data System (ADS)

    Mertz-Kraus, R.; Kocot, Y.; Gibert, L.; Scott, G. R.; Jochum, K. P.

    2011-12-01

    enhanced rainfall. Stable oxygen and carbon isotope data were derived for the flowstone samples along transects parallel to the LA-ICP-MS profiles. Within the interval of the polarity transition, the δ18O and δ13C ratios decrease abruptly from around -3 to -5% and +1 to -2%, respectively. Although speleothem δ18O can be influenced by several parameters, the most plausible explanation for decreasing values appears to be enhanced rainfall which is consistent with the trace element results. Decreasing δ13C ratios can be linked to increasing cloud coverage as well as cooler and/or wetter conditions thereby influencing the vegetation. Significant geochemical effects are recorded in the Cueva Victoria flowstone indicating relatively rapid transition to a wetter environment, influencing erosion, hydrology, vegetation and biological activity in soils. These effects occur contemporaneously with a Pleistocene polaritiy transition confirming the model of environmental change caused by changes in the Earth's magnetic field.

  2. Charred wood remains in the natufian sequence of el-Wad terrace (Israel): New insights into the climatic, environmental and cultural changes at the end of the Pleistocene

    NASA Astrophysics Data System (ADS)

    Caracuta, Valentina; Weinstein-Evron, Mina; Yeshurun, Reuven; Kaufman, Daniel; Tsatskin, Alexander; Boaretto, Elisabetta

    2016-01-01

    The major social and economic changes associated with the rise of a sedentary lifestyle and the gradual transition to food production in the southern Levant are often considered to have been triggered by climate changes at the end of the Pleistocene (∼20,000-11,000 years BP). This explanation, however, is biased by the scarcity of high-resolution climate records directly associated with human activity and the lack of refined palaeoecological studies from multi-stratified sites in the area. Here, we present the results of an anthracological analysis, carried out on charcoals collected along a continuous column of archaeological sediments in the Natufian site of el-Wad Terrace (Mount Carmel, Israel). We also present the carbon isotopes analysis of 14C-dated archaeological remains of Amygdalus sp. The analyses of charcoal shows the predominance of an oak forest including Quercus calliprinos and ithaburensis around the site during the Early Natufian building phase (∼14,600-13,700 cal BP), and the values of Δ13C point to a high rainfall rate. This period is followed by a marked decrease in the local rainfall between ∼13,700 and 12,000 cal BP). The reduction, culturally associated with the latest Early Natufian and the Late Natufian, is independently recorded by the speleothems of the region: Soreq Cave and Jerusalem Cave. This period incorporates an increase in drought tolerant species such as Amygdalus sp. Thermo-Mediterranean species, such as Olea europaea and Ceratonia siliqua, as well as Pistacia palaestina, which dominate the modern landscape, become established in the Holocene. We conclude that the Natufian settlement at el-Wad Terrace flourished in the context of oak forests, and subsequently occupation intensity decreased in concurrence to the drying trend. This shift does not correspond to the cultural typology (i.e. Early Natufian vs. Late Natufian). Human response to climate change at the terminal Pleistocene Levant was multifaceted and localized. Its

  3. Tropical and High-latitude Surface Ocean Circulation Across The Mid-Pleistocene Transition: Teleconnections And Impacts For Ice-sheet Growth And Environmental Change Onshore

    NASA Astrophysics Data System (ADS)

    McClymont, E. L.; Rosell-Mele, A.; Lloyd, J. M.

    2006-12-01

    The Mid-Pleistocene Transition (MPT) is a major event in the Quaternary record, marking the shift to a dominant glacial/interglacial period of 100-kyr and the development of larger northern hemisphere ice-sheets at ca. 0.9 Ma. The significance of the MPT lies in the change of the global climate system response to external insolation forcing, which cannot account for the strength of the 100-kyr cycles. Existing hypotheses link the MPT to falling atmospheric CO2 concentrations, cooler deep-water temperatures, changes in sea-ice distribution and to the basal conditions of the northern hemisphere ice-sheets. We present alkenone-derived records of sea-surface temperature from the tropical Pacific and the south-east Atlantic spanning 1.5-0.5 Ma, coupled with evidence of arctic/polar water mass distributions in the high northern latitudes of the Atlantic and Pacific Oceans. Interaction between the tropics and high-latitudes across the MPT is suggested by the results presented here. At all sites we find evidence for cooling beginning from 1.15 Ma, supporting the hypotheses invoking cooling of both the atmosphere and deep-waters as a driver of the MPT. Sea-ice expansion from 1.15 Ma is suggested by the equatorward migration of arctic/polar water masses in both the Atlantic and Pacific, which reached their maximum extent at 1.0 Ma. The negative impact of more expansive sea-ice cover to the transport of moisture to the ice-sheet source regions may have been critical to the later development of larger northern hemisphere ice-sheets from 0.9 Ma. Significantly, we find that the MPT was not simply a high-latitude phenomenon, but was accompanied by (and perhaps driven by) significant changes to circulation in the tropical Pacific. Between 1.15 0.9 Ma a secular decrease in mean sea-surface temperatures of c.1.5*C in the eastern tropical Pacific marks an intensification of Walker Circulation and a shift towards a `La Niña'-like circulation state. The associated Trade Wind

  4. Pleistocene lake level changes in Western Mongolia

    NASA Astrophysics Data System (ADS)

    Borodavko, P. S.

    2009-04-01

    Global cooling in the Early Pleistocene caused extensive continental glaciation in the northern hemisphere including the arid areas of Central Asia. The reduction of temperatures (particularly summer temperatures) reduced evaporation and strengthened the importance of precipitation. The simultaneity of "lakes periods" (pluvials) and stages of glaciation is established experience confirmed by investigations in the west of North America and Russia. In the Mongolian Great Lakes Depression new evidence for similar conditions is found. The Great Lakes Depression is one of the largest in Central Asia, and is divided into 2 main Lakes basins: Hyargas Lake Basin and Uvs Lake Basin. The basin is 600-650 km in length with a width of 200-250 km in the north and 60-100 km in the south. Total catchment area is about 186600 km2. The elevation of the basin floor is from 1700 m a.s.l. to 760 m a.s.l., decreasing to the north and south-east. The depression extends south-north and is bounded by mountains: Tannu-Ola to the north, Hangai to the east; Gobi Altai to the south and Mongolian Altay to the west. The maximum elevation of the mountains is 4000 m a.s.l. There are some mountains with an elevation between 2000 and 3000 m a.s.l in the lake catchment. These mountains are not glaciated today. The geological record [1] suggests the Great Lakes Depression already existed in the Mesozoic, but assumed its modern form only during the Pliocene-Quaternary when tectonic movements caused the uplift of the surrounding mountains. A phase of tectonic stability occurred during the Late Quaternary. The depression is filled by Quaternary fluvial, aeolian and lacustrine deposits (e.g. sand, pebbles). The Neogene deposits are represented by coloured clay, marl, sand and sandstone [1]. Hyargas Lake is the end base level of erosion of the lake group consisting of the Hara-Us Nur, Dorgon, Hara Nur and Airag lakes. Hyargas is one of the largest lakes in Mongolia, with a water surface of 1,407 km2. The

  5. Ecological change, range fluctuations and population dynamics during the Pleistocene.

    PubMed

    Hofreiter, Michael; Stewart, John

    2009-07-28

    Apart from the current human-induced climate change, the Holocene is notable for its stable climate. In contrast, the preceding age, the Pleistocene, was a time of intensive climatic fluctuations, with temperature changes of up to 15 degrees C occurring within a few decades. These climatic changes have substantially influenced both animal and plant populations. Until recently, the prevailing opinion about the effect of these climatic fluctuations on species in Europe was that populations survived glacial maxima in southern refugia and that populations died out outside these refugia. However, some of the latest studies of modern population genetics, the fossil record and especially ancient DNA reveal a more complex picture. There is now strong evidence for additional local northern refugia for a large number of species, including both plants and animals. Furthermore, population genetic analyses using ancient DNA have shown that genetic diversity and its geographical structure changed more often and in more unpredictable ways during the Pleistocene than had been inferred. Taken together, the Pleistocene is now seen as an extremely dynamic era, with rapid and large climatic fluctuations and correspondingly variable ecology. These changes were accompanied by similarly fast and sometimes dramatic changes in population size and extensive gene flow mediated by population movements. Thus, the Pleistocene is an excellent model case for the effects of rapid climate change, as we experience at the moment, on the ecology of plants and animals.

  6. Lifestyle and Ice: The Relationship between Ecological Specialization and Response to Pleistocene Climate Change.

    PubMed

    Kašparová, Eva; Van de Putte, Anton P; Marshall, Craig; Janko, Karel

    2015-01-01

    Major climatic changes in the Pleistocene had significant effects on marine organisms and the environments in which they lived. The presence of divergent patterns of demographic history even among phylogenetically closely-related species sharing climatic changes raises questions as to the respective influence of species-specific traits on population structure. In this work we tested whether the lifestyle of Antarctic notothenioid benthic and pelagic fish species from the Southern Ocean influenced the concerted population response to Pleistocene climatic fluctuations. This was done by a comparative analysis of sequence variation at the cyt b and S7 loci in nine newly sequenced and four re-analysed species. We found that all species underwent more or less intensive changes in population size but we also found consistent differences between demographic histories of pelagic and benthic species. Contemporary pelagic populations are significantly more genetically diverse and bear traces of older demographic expansions than less diverse benthic species that show evidence of more recent population expansions. Our findings suggest that the lifestyles of different species have strong influences on their responses to the same environmental events. Our data, in conjunction with previous studies showing a constant diversification tempo of these species during the Pleistocene, support the hypothesis that Pleistocene glaciations had a smaller effect on pelagic species than on benthic species whose survival may have relied upon ephemeral refugia in shallow shelf waters. These findings suggest that the interaction between lifestyle and environmental changes should be considered in genetic analyses.

  7. Lifestyle and Ice: The Relationship between Ecological Specialization and Response to Pleistocene Climate Change

    PubMed Central

    Kašparová, Eva; Van de Putte, Anton P.; Marshall, Craig; Janko, Karel

    2015-01-01

    Major climatic changes in the Pleistocene had significant effects on marine organisms and the environments in which they lived. The presence of divergent patterns of demographic history even among phylogenetically closely-related species sharing climatic changes raises questions as to the respective influence of species-specific traits on population structure. In this work we tested whether the lifestyle of Antarctic notothenioid benthic and pelagic fish species from the Southern Ocean influenced the concerted population response to Pleistocene climatic fluctuations. This was done by a comparative analysis of sequence variation at the cyt b and S7 loci in nine newly sequenced and four re-analysed species. We found that all species underwent more or less intensive changes in population size but we also found consistent differences between demographic histories of pelagic and benthic species. Contemporary pelagic populations are significantly more genetically diverse and bear traces of older demographic expansions than less diverse benthic species that show evidence of more recent population expansions. Our findings suggest that the lifestyles of different species have strong influences on their responses to the same environmental events. Our data, in conjunction with previous studies showing a constant diversification tempo of these species during the Pleistocene, support the hypothesis that Pleistocene glaciations had a smaller effect on pelagic species than on benthic species whose survival may have relied upon ephemeral refugia in shallow shelf waters. These findings suggest that the interaction between lifestyle and environmental changes should be considered in genetic analyses. PMID:26535569

  8. Late Miocene to Pleistocene Environmental Changes in the Western Qaidam Basin (NE Tibetan Plateau) Revealed By Magnetic Properties in Lacustrine Sediments

    NASA Astrophysics Data System (ADS)

    Herb, C.; Appel, E.; Zhang, W.; Koutsodendris, A.; Fang, X.; Pross, J.

    2014-12-01

    The advantage of studying magnetic properties of the lacustrine sediments deposited in the Qaidam paleolake to reconstruct past environmental changes was shown in detail for the 940-m-long drill core SG-1 (2.69-0.08 Ma) recovered from the western Qaidam Basin. Especially magnetic susceptibility (χ) turned out to be a useful proxy indicating past humidity changes in the study region. The causes of χ variation could be related to weathering (low-temperature oxidation) in the catchment area and a changing catchment area, respectively. To benefit further from magnetic properties as high-resolution paleoclimate proxies in the Qaidam paleolake, we expand our magnetic record to the late Miocene by investigating magnetic properties of the 723-m deep drilling SG-1b. While SG-1 was drilled in the flat lying strata of the Chahansilatu sub-basin, SG-1b was recovered from the adjacent Jianshan anticline (in ~20 km distance from SG-1). Magnetostratigraphy of core SG-1b detects a time span ranging from 7.3 to 1.6 Ma, missing the younger sequence as a consequence of the anticline structure. We analyze climatic implications of the magnetic record of SG-1b, especially by observing 750 hysteresis loops and 20 FORC diagrams, and check for small-scale variations of the studied sediments by comparing χ of bulk samples (in the order of 10 g) and samples used for hysteresis measurements (in the order of 0.01 g). Spectral analysis based on the time scale provided by magnetostratigraphy reveals variations of χ in the order of Milankovitch cycles (precession, obliquity, and eccentricity) indicating insolation changes as one important driving factor of the magnetic concentration signal. The magnetic records of SG-1 and SG-1b are also used to check implications of the anticline structure on magnetic signatures by comparing the overlapping interval of both cores (2.69-1.6 Ma).

  9. Small mammal diversity loss in response to late-Pleistocene climatic change.

    PubMed

    Blois, Jessica L; McGuire, Jenny L; Hadly, Elizabeth A

    2010-06-10

    Communities have been shaped in numerous ways by past climatic change; this process continues today. At the end of the Pleistocene epoch about 11,700 years ago, North American communities were substantially altered by the interplay of two events. The climate shifted from the cold, arid Last Glacial Maximum to the warm, mesic Holocene interglacial, causing many mammal species to shift their geographic distributions substantially. Populations were further stressed as humans arrived on the continent. The resulting megafaunal extinction event, in which 70 of the roughly 220 largest mammals in North America (32%) became extinct, has received much attention. However, responses of small mammals to events at the end of the Pleistocene have been much less studied, despite the sensitivity of these animals to current and future environmental change. Here we examine community changes in small mammals in northern California during the last 'natural' global warming event at the Pleistocene-Holocene transition and show that even though no small mammals in the local community became extinct, species losses and gains, combined with changes in abundance, caused declines in both the evenness and richness of communities. Modern mammalian communities are thus depauperate not only as a result of megafaunal extinctions at the end of the Pleistocene but also because of diversity loss among small mammals. Our results suggest that across future landscapes there will be some unanticipated effects of global change on diversity: restructuring of small mammal communities, significant loss of richness, and perhaps the rising dominance of native 'weedy' species.

  10. African climate change and faunal evolution during the Pliocene-Pleistocene

    NASA Astrophysics Data System (ADS)

    deMenocal, Peter B.

    2004-03-01

    Environmental theories of African faunal evolution state that important evolutionary changes during the Pliocene-Pleistocene interval (the last ca. 5.3 million years) were mediated by changes in African climate or shifts in climate variability. Marine sediment sequences demonstrate that subtropical African climate periodically oscillated between markedly wetter and drier conditions, paced by earth orbital variations, with evidence for step-like (±0.2 Ma) increases in African climate variability and aridity near 2.8 Ma, 1.7 Ma, and 1.0 Ma, coincident with the onset and intensification of high-latitude glacial cycles. Analysis of the best dated and most complete African mammal fossil databases indicates African faunal assemblage and, perhaps, speciation changes during the Pliocene-Pleistocene, suggesting more varied and open habitats at 2.9-2.4 Ma and after 1.8 Ma. These intervals correspond to key junctures in early hominid evolution, including the emergence of our genus Homo. Pliocene-Pleistocene shifts in African climate, vegetation, and faunal assemblages thus appear to be roughly contemporary, although detailed comparisons are hampered by sampling gaps, dating uncertainties, and preservational biases in the fossil record. Further study of possible relations between African faunal and climatic change will benefit from the accelerating pace of important new fossil discoveries, emerging molecular biomarker methods for reconstructing African paleovegetation changes, tephra correlations between terrestrial and marine sequences, as well as continuing collaborations between the paleoclimatic and paleoanthropological communities.

  11. Pleistocene changes in the fauna and flora of South america.

    PubMed

    Vuilleumier, B S

    1971-08-27

    forest elements (40) now justify the conclusion that the floras and faunas of these areas were also greatly affected by Pleistocene climatic shifts. In the broad region of South America that lies within the tropics, a series of humid-arid cycles (Appendix, 6, 8-10) drastically and repeatedly altered vegetation patterns during the Quaternary. Both montane and lowland rainforests were fragmented during dry periods and were able to reexpand during humid phases. Speciation of forest elements was initiated-and sometimes completed-in isolated patches of the fragmented forest. Secondary contact, with hybridization or reunition of populations that did not become reproductively isolated, occurred in periods of reexpansion. These biological data, combined with supportive geological evidence (Appendix, 1-11), show that climatic events during the last million or so years have affected the biota of South America as much as the Pleistocene glacial changes affected the biotas of Eurasia and North America. Since most of South America lies within tropical latitudes, it is suggested here that part of the diversity of species in the tropical areas of this continent is due to two historical factors: the lack of wholesale elimination of species (compared with northern and high latitudes), and ample opportunity for speciation in successive periods of ecological isolation. The apparent paradox of the wealth of species in the "stable tropics" is partially explained by the fact that the tropics have probably been quite unstable, from the point of view of their biotas, during the Pleistocene and perhaps part of the Tertiary.

  12. Late Pleistocene climate change, nutrient cycling, and the megafaunal extinctions in North America

    NASA Astrophysics Data System (ADS)

    Faith, J. Tyler

    2011-06-01

    This study proposes an ecological mechanism for the terminal Pleistocene population collapse and subsequent extinction of North American megafauna. Observations of modern ecosystems indicate that feedback mechanisms between plant nutrient content, nitrogen cycling, and herbivore-plant interactions can vary between a nutrient accelerating mode favoring increased herbivore biomass and a nutrient decelerating mode characterized by reduced herbivore biomass. These alternate modes are determined largely by plant nitrogen content. Plant nitrogen content is known to be influenced by atmospheric CO 2 concentrations, temperature, and precipitation. It is argued that Lateglacial climate change, particularly increases in atmospheric CO 2, shifted herbivore-ecosystem dynamics from a nutrient accelerating mode to a nutrient decelerating mode at the end of the Pleistocene, leading to reduced megafaunal population densities. An examination of Sporormiella records - a proxy for megaherbivore biomass - indicates that megafaunal populations collapsed first in the east and later in the west, possibly reflecting regional differences in precipitation or vegetation structure. The fortuitous intersection of the climatically driven nitrogen sink, followed by any one or combination of subsequent anthropogenic, environmental, or extra-terrestrial mechanisms could explain why extinctions took place at the end of the Pleistocene rather than during previous glacial-interglacial cycles.

  13. Gradual and abrupt changes during the Mid-Pleistocene Transition

    NASA Astrophysics Data System (ADS)

    Ford, Heather L.; Sosdian, Sindia M.; Rosenthal, Yair; Raymo, Maureen E.

    2016-09-01

    During the Mid-Pleistocene Transition (MPT), the dominant glacial-interglacial cyclicity as inferred from the marine δ18O records of benthic foraminifera (δ18Obenthic) changed from 41 kyr to 100 kyr years in the absence of a comparable change in orbital forcing. Currently, only two Mg/Ca-derived, high-resolution bottom water temperature (BWT) records exist that can be used with δ18Obenthic records to separate temperature and ice volume signals over the Pleistocene. However, these two BWT records suggest a different pattern of climate change occurred over the MPT-a record from North Atlantic DSDP Site 607 suggests BWT decreased with no long-term trend in ice volume over the MPT, while South Pacific ODP Site 1123 suggests that BWT has been relatively stable over the last 1.5 Myr but that there was an abrupt increase in ice volume at ∼900 kyr. In this paper we attempt to reconcile these two views of climate change across the MPT. Specifically, we investigated the suggestion that the secular BWT trend obtained from Mg/Ca measurements on Cibicidoides wuellerstorfi and Oridorsalis umbonatus species from N. Atlantic Site 607 is biased by the possible influence of Δ[CO32-] on Mg/Ca values in these species by generating a low-resolution BWT record using Uvigerina spp., a genus whose Mg/Ca values are not thought to be influenced by Δ[CO32-]. We find a long-term BWT cooling of ∼2-3°C occurred from 1500 to ∼500 kyr in the N. Atlantic, consistent with the previously generated C. wuellerstorfi and O. umbonatus BWT record. We also find that changes in ocean circulation likely influenced δ18Obenthic, BWT, and δ18Oseawater records across the MPT. N. Atlantic BWT cooling starting at ∼1.2 Ma, presumably driven by high-latitude cooling, may have been a necessary precursor to a threshold response in climate-ice sheet behavior at ∼900 ka. At that point, a modest increase in ice volume and thermohaline reorganization may have caused enhanced sensitivity to the 100 kyr

  14. Environmentally controlled succession in a late Pleistocene coral reef (Sinai, Egypt)

    NASA Astrophysics Data System (ADS)

    Mewis, H.; Kiessling, W.

    2013-03-01

    The concept of ecological succession has been frequently applied in the study of ancient reefs. Whereas Paleozoic and Mesozoic reefs are commonly thought to reveal an autogenic primary—climax zonation, patterns in Neogene and Quaternary reefs are much more diverse. Here, we describe a well-preserved late Pleistocene coral reef from Dahab on Sinai Peninsula (Egypt), which shows a distinct zonation that resembles an ecological succession. In contrast to classical examples of ecological successions, species composition, paleoenvironmental conditions, and coral biodiversity of the Dahab reef indicate an allogenic, sea-level controlled community change, from marginal marine to reef slope and back reef. A review of the literature confirms that autogenic, short-term successions are virtually absent in Quaternary reefs. We predict that long generation times of corals make it unlikely that classical autogenic successions develop in reefs at all, unless environmental conditions are unusually stable.

  15. Asynchronous demographic responses to Pleistocene climate change in Eastern Nearctic vertebrates.

    PubMed

    Burbrink, Frank T; Chan, Yvonne L; Myers, Edward A; Ruane, Sara; Smith, Brian Tilston; Hickerson, Michael J

    2016-12-01

    Pleistocene climatic cycles altered species distributions in the Eastern Nearctic of North America, yet the degree of congruent demographic response to the Pleistocene among codistributed taxa remains unknown. We use a hierarchical approximate Bayesian computational approach to test if population sizes across lineages of snakes, lizards, turtles, mammals, birds, salamanders and frogs in this region expanded synchronously to Late Pleistocene climate changes. Expansion occurred in 75% of 74 lineages, and of these, population size trajectories across the community were partially synchronous, with coexpansion found in at least 50% of lineages in each taxonomic group. For those taxa expanding outside of these synchronous pulses, factors related to when they entered the community, ecological thresholds or biotic interactions likely condition their timing of response to Pleistocene climate change. Unified timing of population size change across communities in response to Pleistocene climate cycles is likely rare in North America.

  16. Reconstructing Environmental Change Using Lake Varves as a Climate Proxy

    ERIC Educational Resources Information Center

    Dempsey, Christopher; Bodzin, Alec; Cirucci, Lori; Anastasio, David; Sahagian, Dork

    2012-01-01

    In this article, the authors describe an investigative activity in which their eighth-grade students reconstructed past environmental change in the New England area using data from lake varves in central Vermont to examine evidence of climate change. The investigation uses an authentic paleoclimate record (Ridge 2011) from the Pleistocene epoch,…

  17. The consequences of pleistocene climate change on lowland neotropical vegetation

    SciTech Connect

    De Oliveira, P.E.; Colinvaux, P.A. )

    1994-06-01

    Palynological reconstructions indicate that lowland tropical America was subject to intense cooling during the last ice-age. The descent of presently montane taxa into the lowlands of Amazonia and Minas Gerais indicate temperature depressions ranging from 5[degrees]C to 9[degrees]C cooler-than-present. The strengthened incursion of southerly airmasses caused a reassortment of vegetation throughout Amazonia. Presently allopatric species are found to have been sympatric as novel forest assemblages and formed and dissolved. Modest drying, perhaps a 20% reduction in precipitation, accounts for all the records that show a Pleistocene expansion of savanna. No evidence is found to support the fragmentation of Amazonian forests during glacial times, and the hypothesis of forest refuges as an explanation of tropical speciation is rejected on empirical grounds.

  18. Modelled ocean changes at the Plio-Pleistocene transition driven by Antarctic ice advance

    PubMed Central

    Hill, Daniel J.; Bolton, Kevin P.; Haywood, Alan M.

    2017-01-01

    The Earth underwent a major transition from the warm climates of the Pliocene to the Pleistocene ice ages between 3.2 and 2.6 million years ago. The intensification of Northern Hemisphere Glaciation is the most obvious result of the Plio-Pleistocene transition. However, recent data show that the ocean also underwent a significant change, with the convergence of deep water mass properties in the North Pacific and North Atlantic Ocean. Here we show that the lack of coastal ice in the Pacific sector of Antarctica leads to major reductions in Pacific Ocean overturning and the loss of the modern North Pacific Deep Water (NPDW) mass in climate models of the warmest periods of the Pliocene. These results potentially explain the convergence of global deep water mass properties at the Plio-Pleistocene transition, as Circumpolar Deep Water (CDW) became the common source. PMID:28252023

  19. Modelled ocean changes at the Plio-Pleistocene transition driven by Antarctic ice advance

    NASA Astrophysics Data System (ADS)

    Hill, Daniel J.; Bolton, Kevin P.; Haywood, Alan M.

    2017-03-01

    The Earth underwent a major transition from the warm climates of the Pliocene to the Pleistocene ice ages between 3.2 and 2.6 million years ago. The intensification of Northern Hemisphere Glaciation is the most obvious result of the Plio-Pleistocene transition. However, recent data show that the ocean also underwent a significant change, with the convergence of deep water mass properties in the North Pacific and North Atlantic Ocean. Here we show that the lack of coastal ice in the Pacific sector of Antarctica leads to major reductions in Pacific Ocean overturning and the loss of the modern North Pacific Deep Water (NPDW) mass in climate models of the warmest periods of the Pliocene. These results potentially explain the convergence of global deep water mass properties at the Plio-Pleistocene transition, as Circumpolar Deep Water (CDW) became the common source.

  20. Modelled ocean changes at the Plio-Pleistocene transition driven by Antarctic ice advance.

    PubMed

    Hill, Daniel J; Bolton, Kevin P; Haywood, Alan M

    2017-03-02

    The Earth underwent a major transition from the warm climates of the Pliocene to the Pleistocene ice ages between 3.2 and 2.6 million years ago. The intensification of Northern Hemisphere Glaciation is the most obvious result of the Plio-Pleistocene transition. However, recent data show that the ocean also underwent a significant change, with the convergence of deep water mass properties in the North Pacific and North Atlantic Ocean. Here we show that the lack of coastal ice in the Pacific sector of Antarctica leads to major reductions in Pacific Ocean overturning and the loss of the modern North Pacific Deep Water (NPDW) mass in climate models of the warmest periods of the Pliocene. These results potentially explain the convergence of global deep water mass properties at the Plio-Pleistocene transition, as Circumpolar Deep Water (CDW) became the common source.

  1. Late Pleistocene-early Holocene karst features, Laguna Madre, south Texas: A record of climate change

    SciTech Connect

    Prouty, J.S.

    1996-09-01

    A Pleistocene coquina bordering Laguna Madre, south Texas, contains well-developed late Pleistocene-early Holocene karst features (solution pipes and caliche crusts) unknown elsewhere from coastal Texas. The coquina accumulated in a localized zone of converging longshore Gulf currents along a Gulf beach. The crusts yield {sup 14}C dates of 16,660 to 7630 B.P., with dates of individual crust horizons becoming younger upwards. The karst features provide evidence of regional late Pleistocene-early Holocene climate changes. Following the latest Wisconsinan lowstand 18,000 B.P. the regional climate was more humid and promoted karst weathering. Partial dissolution and reprecipitation of the coquina formed initial caliche crust horizons; the crust later thickened through accretion of additional carbonate laminae. With the commencement of the Holocene approximately 11,000 B.P. the regional climate became more arid. This inhibited karstification of the coquina, and caliche crust formation finally ceased about 7000 B.P.

  2. Differential resilience of ancient sister lakes Ohrid and Prespa to environmental disturbances during the Late Pleistocene

    NASA Astrophysics Data System (ADS)

    Jovanovska, Elena; Cvetkoska, Aleksandra; Hauffe, Torsten; Levkov, Zlatko; Wagner, Bernd; Sulpizio, Roberto; Francke, Alexander; Albrecht, Christian; Wilke, Thomas

    2016-02-01

    Ancient lakes, such as lakes Ohrid and Prespa on the Balkan Peninsula, have become model systems for studying the link between geological and biotic evolution. Recently, the scientific deep-drilling project Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) was initiated to better understand the environmental, climatic, and limnological evolution of the lake. It revealed that Lake Ohrid experienced a number of environmental disturbances during its ca. 2.0 million year long history. These are comprised of disturbances that lasted over longer periods of time ("press events") such as glacial-interglacial cycles and Heinrich events, as well as sudden and short disturbances ("pulse events") like the deposition of landslides, earthquakes, and volcanic ash depositions. The latter includes one of the most severe volcanic episodes during the Late Pleistocene: the eruption of the Campanian Ignimbrite (known as Y-5 marine tephra layer) from the Campi Flegrei caldera, dated to 39.6 ± 0.1 thousand years ago. The event is recorded by the deposition of a ca. 15 cm thick tephra layer in sediment cores of lakes Ohrid (DEEP-5045-1) and Prespa (Co1204). Coincidently, this pulse event is superimposed by the Heinrich H4 event, 40.4-38.4 thousand years ago. In the current paper, diatoms were used as proxies to compare the responses of these lakes to the Y-5 (pulse) and the H4 (press) disturbances. Based on stratigraphically constrained incremental sum of squares cluster (CONISS) and unconstrained Partitioning Around Medoids (PAM) analyses, we found little evidence that diatom community compositions in either lake responded to the H4 event. However, the Y-5 influx caused clear and rapid diatom community changes. After the initial response, community compositions in Lake Ohrid and, to a lesser extent, in Lake Prespa slowly returned to their quasi pre-disturbance state. Moreover, there is no evidence for disturbance-related extinction events. The combined

  3. Paleolimnological reconstruction of environmental variability during the Late Pleistocene and Holocene in the south-east Baltic region

    NASA Astrophysics Data System (ADS)

    Kublitskiy, Iurii; Subetto, Dmitriy; Druzhinina, Olga; Kulkova, Marianna; Arslanov, Khikmatula

    2016-04-01

    The main goal of our research is the high-resolution reconstruction of environmental and climatic changes in SE Baltic region since the Last Glacial Maximum by palaeolimnological data. The 6 objects - lakes and peat-bogs, were studied since 2009 in the Kaliningrad region, Russian Federation. According to palaeolimnological studies of bottom sediments of the Kamyshovoe Lake (N 54°22,6`; E22°42,8`, 189 m a.s.l.), located in the Vishtynets Highland, the south-east part of Kaliningrad district, the environmental and climatic changes after the late glacial have been reconstructed. At that moment the radiocarbon and loss-on-ignition (LOI) data, geochemistry and diatom analysis for the whole sediment core, and pollen analyze for the bottom part of the core have been completed. According to the pollen data the Alleröd interstadial starts at 13 200 cal. yrs BP and is marked by the rising of birch and pine pollen. The transition to the Younger Dryas around 12 700 cal. yrs BP corresponds with the development of patches of shrublands in which light-demanding species, such as juniper, flourished and communities of steppe herbs. The late Preboreal is marked by the appearance of Populus and an increase of the role of grasses in the vegetation cover 11 300-11 100 cal. yrs BP (Druzinina et al., 2015). The Holocene climatic zones have been identified by LOI and geochemistry analyses. The Boreal period started about 10 200 cal. yrs BP, Atlantic around 9100 cal. yrs BP, Subboreal 5800 cal. yrs BP, and Subatlantic 3200 cal. yrs BP (Kublitskiy et al., 2015). During the conference the new palaeolimnological data of environmental variability during the late Pleistocene and Holocene in SE Baltic region will be presented. Acknowledgements The investigations have been granted by the Russian Fund for Basic Research (12-05-33013, 13-05-41457, 15-35-50721). References Druzhinina, O., Subetto, D., Stančikaitė, M., Vaikutienė, G., Kublitsky, J., Arslanov, Kh., 2015. Sediment record from the

  4. Evolution in the sabre-tooth cat, Smilodon fatalis, in response to Pleistocene climate change.

    PubMed

    Meachen, J A; O'Keefe, F R; Sadleir, R W

    2014-04-01

    The late Pleistocene was a time of environmental change, culminating in an extinction event. Few fossil localities record a temporal series of carnivore fossil populations from this interesting interval as well as Rancho La Brea (RLB). We analysed mandibles of Smilodon fatalis from RLB using 2-D geometric morphometrics to examine whether, and how, mandibular shape changes through time. Smilodon fatalis shows mandibular evolution with oscillations between a small, ancestral-type morph in pits 77 (≈37 Kybp) and 2051 (≈26 Kybp), a larger, more derived morph in pits 91 (≈28 Kybp) and 61-67 (≈13.6 Kybp), and an intermediate morph from pit 13 (≈17.7 Kybp). These oscillations end in pit 61-67, with greatest body size, and are estimated to have its widest gape and lowest bite force. Additionally, variation is lowest in pit 61-67, which was deposited concurrent with the Bølling–Allerød warming event, which may have important implications for the timing or conditions during the extinction event. Contra to a temporal Bergmann's rule, such rapid warming events appear to be correlated with larger, derived, morphologies whereas static, cooler, climates correlate with gracile, ancestral morphologies.

  5. Differential resilience of ancient sister lakes Ohrid and Prespa to environmental disturbances during the Late Pleistocene

    NASA Astrophysics Data System (ADS)

    Jovanovska, E.; Cvetkoska, A.; Hauffe, T.; Levkov, Z.; Wagner, B.; Sulpizio, R.; Francke, A.; Albrecht, C.; Wilke, T.

    2015-09-01

    Ancient lakes, like lakes Ohrid and Prespa on the Balkan Peninsula, have become model systems for studying the link between geological and biotic evolution. Recently the scientific deep drilling program "Scientific Collaboration on Past Speciation Conditions in Lake Ohrid" (SCOPSCO) has been launched to better understand the environmental, climatic and limnological evolution of the lake. It revealed that Lake Ohrid experienced a number of environmental disturbances during its ca. 2.0 million year long history. They comprise disturbances that lasted over longer periods of times ("press events") such as Heinrich events as well as sudden and short disturbances ("pulse events") like the deposition of volcanic ashes. The latter include one of the most severe volcanic episodes during the Late Pleistocene, the eruption of the Campanian Ignimbrite (known as Y-5 marine tephra layer) from the Campi Flegrei caldera, dated at 39.6 ± 0.1 ka ago. The event is recorded by the deposition of a ca. 15 cm thick Y-5 tephra layer in sediment cores of lakes Ohrid (DEEP-5045-1) and Prespa (Co1204). This pulse event is overlain by the Heinrich event 4 (H4), 40.0-38.0 ka ago. In the current paper, diatoms were used as proxies to compare the responses of these lakes to the Y-5 (pulse) and the H4 (press) disturbances. Based on stratigraphically constrained incremental sum of squares cluster (CONISS) and unconstrained Partitioning Around Medoids (PAM) analyses, we found only little evidence that the diatom community compositions in either lake responded to the H4 event. However, the Y-5 influx caused clear and rapid diatom community changes. After the initial response, community composition in Lake Ohrid and, to a lesser extent, in Lake Prespa slowly returned to their quasi pre-disturbance state. Moreover, there is no evidence for disturbance-related extinction events. The combined evidence from these findings suggests that lakes Ohrid and Prespa likely did not experience regime shifts. It

  6. Changing Environmentally Relevant Behaviour.

    ERIC Educational Resources Information Center

    Gudgion, T. J.; Thomas, M. Pugh

    1991-01-01

    Considered is the role of psychology in helping to change those human behaviors which have deleterious environmental effects. The foremost conclusion is that behavioral psychology can offer practical techniques for such change, yet there are indications that enduring behaviors may be better realized through the intrinsic motivation maintained by…

  7. Plio-Pleistocene climate change in Asian: Evidence from terrestrial lipids at ODP Site 1143 in the South China Sea

    NASA Astrophysics Data System (ADS)

    Li, L.; Wang, H.; Wang, P.

    2010-12-01

    the late Pleistocene than Pliocene (a warm periods than present), suggested the alkane indices in the studied region mainly correspond to the humidity other than temperature. Alkane indices over the past 5 Ma indicate relative humid climate during the Pliocene, especially in the early Pliocene, which is the most humid climate in the 5 Ma period of time. But since the onset of northern hemisphere glaciation, the climate became progressively arid until 1.5-1.2 Ma; after that time the climate changed to a huge alternation of dry and humid climates. The uplift of the Tibetan Plateau, the closure of the Panamanian Seaway, the formation of east -west equatorial temperature gradient may exert a complex and profound effect upon atmospheric circulation and environmental changes of Eastern Asia over the Plio-Pleistocene periods.

  8. A lacustrine record from Lop Nur, Xinjiang, China: Implications for paleoclimate change during Late Pleistocene

    USGS Publications Warehouse

    Chao, L.; Zicheng, P.; Dong, Y.; Weiguo, L.; Zhaofeng, Z.; Jianfeng, H.; Chenlin, C.

    2009-01-01

    Climate variability during the Late Pleistocene is studied from the proxies in core CK-2 drilled from the Luobei Depression (91??03???E, 40??47???N), Lop Nur in the eastern Tarim Basin, Xinjiang, China. Geophysical and geochemical properties, including magnetic susceptibility, granularity, chroma, carbonate content, loss on ignition and trace elements, have been determined to reconstruct the environmental evolution of the area during 32-9 ka BP. The chronology is established by uranium-thorium disequilibrium dating techniques. Our data suggest four paleoclimate stages, indicating glacial variations between cold-humid and warm-arid environments. A period of extreme humidity occurred during 31,900-19,200 yr BP is attributed the last glacial maximum (LGM). The period was followed by a warm-arid episode during 19,200-13,500 yr BP. Then a cold-humid interval during 13,500-12,700 yr BP may correspond to another cooling phases at high latitudes of the Northern Hemisphere. The last stage from 12,700 to 9000 yr BP has a trend that the climate turned warm and arid. The Lop Nur region is characterized by particularly humid stadials and arid interstadials. The climate variability in Lop Nur was constrained by global climate change because it is correlated with Dansgaard-Oeschger and Heinrich events, which were observed at the northern high latitudes. The synchroneity of the palaeoclimatic events suggested that cold air activity at the northern high latitudes was the most important factor that influenced the climate evolution in the Lop Nur region. A probable mechanism that involves the migration of westerly winds is proposed to interpret this synchroneity. ?? 2008 Elsevier Ltd.

  9. Early hominid evolution and ecological change through the African Plio-Pleistocene.

    PubMed

    Reed, K E

    1997-01-01

    The habitats in which extinct hominids existed has been a key issue in addressing the origin and extinction of early hominids, as well as in understanding various morphological and behavioral adaptations. Many researchers postulated that early hominids lived in an open savanna (Dart, 1925; Robinson, 1963; Howell, 1978). However, Vrba (1985, 1988) has noted that a major global climatic and environmental shift from mesic, closed to xeric, open habitats occurred in the late African Pliocene (approximately 2.5 m.y.a.), thus implying that the earliest hominids existed in these mesic, wooded environs. This climatic shift is also suggested to have contributed to a pulse in speciation events with turnovers of many bovid and possibly hominid species. Previous environmental reconstructions of hominid localities have concentrated on taxonomic identities and taxonomic uniformitarianism to provide habitat reconstructions (e.g., Vrba, 1975; Shipman & Harris, 1988). In addition, relative abundances of species are often used to reconstruct a particular environment, when in fact taphonomic factors could be affecting the proportions of taxa. This study uses the morphological adaptations of mammalian assemblages found with early hominids to reconstruct the habitat based on each species' ecological adaptations, thus minimizing problems introduced by taxonomy and taphonomy. Research presented here compares east and south African Plio-Pleistocene mammalian fossil assemblages with 31 extant mammalian communities from eight different habitat types. All communities are analyzed through ecological diversity methods, that is, each species trophic and locomotor adaptations are used to reconstruct an ecological community and derive its vegetative habitat. Reconstructed habitats show that Australopithecus species existed in fairly wooded, well-watered regions. Paranthropus species lived in similar environs and also in more open regions, but always in habitats that include wetlands. Homo is the

  10. The circumboreal tundra-taiga interface: late Pleistocene and Holocene changes.

    PubMed

    Payette, S; Eronen, M; Jasinski, J J P

    2002-08-01

    Creating a global perspective on past treeline changes is problematic due to the varying methods and definitions used. A general lack of a detailed description of the modern treeline position and vegetation complicates any comparative analysis of the magnitude of the most important changes. However, one seemingly common factor in most regions was an extremely rapid dispersal of trees when climate warmed drastically from full glacial conditions. Most Arctic treelines reached their northernmost positions in the early Holocene and receded to present positions starting at about 5.8 ka. The early occupation of the northernmost sites in ice-free and early deglaciated areas was possible because of the close proximity of invading trees in nearby glacial refugia, particularly in Fennoscandia and northern Russia. In Canada, the Northwest Territories and Quebec-Labrador were out of phase with this general trend due to their late deglaciation. However, even here colonization was rapid, indicating that the tree species were present adjacent to the glaciers. Following this trend and based on the present evidence, we propose a scenario of a continuous but modest occupation of eastern Beringia by spruce during the late-Pleistocene instead of an exceptionally rapid spread of conifers from the glacial refugium south of the Laurentide ice sheet (2000 to 3000 km in about 200 years), which typically has been assumed. Macrofossil evidence of scattered occurrences of "exotic species" (for instance Siberian larch in central Sweden) far from their natural range limits in the early Holocene highlight the disparity between pollen and macrofossil analyses. It questions the validity of assigned pollen percentages to indicate the presence of a species within a region as these species were not observed in the pollen record. Thus, it is likely that trees were present at any given site well before the rise in pollen abundance. There is still a large potential to improve our knowledge about the

  11. Were the Late Pleistocene climatic changes responsible for the disappearance of the European spotted hyena populations? Hindcasting a species geographic distribution across time

    NASA Astrophysics Data System (ADS)

    Varela, Sara; Lobo, Jorge M.; Rodríguez, Jesús; Batra, Persaram

    2010-08-01

    This article examines the role of the Late Pleistocene climatic changes in the disappearance of the European populations of spotted hyenas. A species distribution model was built using both current and past environmental requirements of the species. Model projections were made with climatic scenarios provided by the GENESIS 2.0 General Circulation Model (126 ka, 42 ka, 30 ka and 21 ka). Those projections indicate (1) that during the Late Pleistocene warm scenarios spotted hyenas should have been widespread in Europe, and (2) that during the last glacial maximum their potential climatically suitable geographic distribution diminished in size. The decrease in the potential climatic distribution was strictly restricted to Northern Europe. Climatic conditions in Southern Europe during the Late Pleistocene remained within the spotted hyena climatic tolerance. Hence, climate changes could have directly affected the Northern distribution of the species during the last glaciations. However, climate change alone is not sufficient to have caused the disappearance of the spotted hyena populations in Southern Europe. That is, other factors, such as prey abundance or human ecological impacts, in addition to climatic change, are needed to completely account for extinction of the European spotted hyena.

  12. Global climate changes drive ecological specialization of mammal faunas: trends in rodent assemblages from the Iberian Plio-Pleistocene

    PubMed Central

    2013-01-01

    Background Several macroevolutionary hypotheses propose a synchrony between climatic changes and variations in the structure of faunal communities. Some of them focus on the importance of the species ecological specialization because of its effects on evolutionary processes and the resultant patterns. Particularly, Vrba’s turnover pulse hypothesis and resource-use hypothesis revolve around the importance of biome inhabitation. In order to test these hypotheses, we used the Biomic Specialization Index, which is based on the number of biomes occupied by each species, and evaluated the changes in the relative importance of generalist and specialist rodents in more than forty fossil sites from the Iberian Plio-Pleistocene. Results Our results indicate that there was a decrease in the specialization degree of rodent faunas during the Pliocene due to the global cooling that triggered the onset of the glacial events of the Cenozoic (around 2.75 Ma). The subsequent faunal transition after this critical paleoenvironmental event was characterized by an increase of specialization related to the adaptation to the new environmental conditions, which was mainly associated with the Pleistocene radiation of Arvicolinae (voles). Conclusions The pattern of faunal turnover is correlated with the development of the modern glaciations in the Northern Hemisphere around 2.75 Ma, and represents a reorganization of the rodent communities, as suggested by the turnover pulse hypothesis. Our data also support the resource-use hypothesis, which presumes the role of the degree of specialization in resources specifically related to particular biomes as a driver of differential speciation and extinction rates. These results stress the intimate connection between ecological and evolutionary changes. PMID:23627696

  13. Late Pleistocene (MIS5-3) environmental reconstruction from north-eastern Iberia through microvertebrate and palaeobotanical records

    NASA Astrophysics Data System (ADS)

    Allue, Ethel; Bennàssar, Maria; Biltekin, Demet; Blain, Hugues-Alexandre; Burjachs, Francesc; Euba, Itxaso; Expósito, Isabel; Fernández-García, Mónica; López-García, Juan Manuel

    2014-05-01

    The aim of this work is to analyze the environmental changes during the Late Pleistocene on the basis of a multi-approach study based on natural and archaeological deposits from NE Iberian Peninsula. The focussed area, although having a small extension (some 32.000 square kilometres), covers a large range of ecosystems and bioclimatic conditions from the Mediterranean seashore to the summit of the Pyrenean mountain ranges (up to 2000 masl). This synthetical approach includes materials from various contexts including 10 archaeological deposits and a single natural deposit. In this work, plant (pollen and charcoals) and animal (small mammals, amphibians and reptiles) records are being analysed and compared in order to present an overview of the environmental changes occurred from the MIS5 to MIS3. On the first hand, we are using the small-vertebrate records recovered from archaeological deposits. These proxies are mainly the product of pellets from birds of prey and are key ecological markers. On the second hand, palaeobotanical evidences, pollen and charcoal, have different formation processes. Charcoal remains are mostly from archaeological deposits and are due to human activities related to fire showing evidences of the local vegetation. Pollen evidences from archaeological and natural contexts are deposited through natural processes (wind, insects, etc.) and show regional scale vegetation record. Results indicate the presence of temperate elements during all these periods (especially at the seashore area), with a more important representation and extension southwards or changes in altitude from taxa with eurosiberian affinities during coldest periods. Forest coverage, plant and vertebrate distribution along the territory point out a mosaic landscape formed by open areas and forests. These landscapes have probably a more or less Mediterranean or Eurosiberian character depending on the climatic moment and their location with variations along the sequence.

  14. Rodent burrows in late Pleistocene paleosols at Korean Palaeolithic sites and their implications for paleoclimate changes

    NASA Astrophysics Data System (ADS)

    Lim, H.; Park, S.; Lee, J.; Lee, Y.

    2013-12-01

    Rodent burrows are commonly found at many Paleolithic archaeological sites in Korea. They are nearly straight in horizontal view and gently inclined in lateral view. Burrow diameters are mostly 7 - 10cm, and burrow length may reach a few meters. Vertical penetration depths are generally about 1 m from the surface, and the thickness of the burrow-bearing layer is about 1-2 m. Although no remains (bones, teeth, claws, and coprolites) were found within burrows, they are interpreted to have been produced by rodent-like mammals (probably ground squirrels) based on the size and architecture. According to the previous study, the age of these burrows was constrained to be between ca. 40,000 and 25,000 yr BP by tephrochronology, radiocarbon and optically stimulated luminescence dating results (Lim et al., 2007). However, little is known about the reason why these burrows have disappeared after late Pleistocene time. For this question, two explanations can be considered: extinction or migration. Since same kinds of burrows are still found in the high-latitude regions, such as Mongolia and North America, the possibility of extinction can be ruled out. Therefore, migration seems to be the most likely explanation. Our results show that the destruction of habitat caused by climate change during this period is the main reason for the northward migration of burrowing animals. This study suggests that rodent burrows found in the late Pleistocene paleosols can provide useful information on paleoclimate and paleoenvironmental changes.

  15. Climate change frames debate over the extinction of megafauna in Sahul (Pleistocene Australia-New Guinea)

    PubMed Central

    Wroe, Stephen; Field, Judith H.; Archer, Michael; Grayson, Donald K.; Price, Gilbert J.; Louys, Julien; Faith, J. Tyler; Webb, Gregory E.; Davidson, Iain; Mooney, Scott D.

    2013-01-01

    Around 88 large vertebrate taxa disappeared from Sahul sometime during the Pleistocene, with the majority of losses (54 taxa) clearly taking place within the last 400,000 years. The largest was the 2.8-ton browsing Diprotodon optatum, whereas the ∼100- to 130-kg marsupial lion, Thylacoleo carnifex, the world’s most specialized mammalian carnivore, and Varanus priscus, the largest lizard known, were formidable predators. Explanations for these extinctions have centered on climatic change or human activities. Here, we review the evidence and arguments for both. Human involvement in the disappearance of some species remains possible but unproven. Mounting evidence points to the loss of most species before the peopling of Sahul (circa 50–45 ka) and a significant role for climate change in the disappearance of the continent’s megafauna. PMID:23650401

  16. Climate change frames debate over the extinction of megafauna in Sahul (Pleistocene Australia-New Guinea).

    PubMed

    Wroe, Stephen; Field, Judith H; Archer, Michael; Grayson, Donald K; Price, Gilbert J; Louys, Julien; Faith, J Tyler; Webb, Gregory E; Davidson, Iain; Mooney, Scott D

    2013-05-28

    Around 88 large vertebrate taxa disappeared from Sahul sometime during the Pleistocene, with the majority of losses (54 taxa) clearly taking place within the last 400,000 years. The largest was the 2.8-ton browsing Diprotodon optatum, whereas the ∼100- to 130-kg marsupial lion, Thylacoleo carnifex, the world's most specialized mammalian carnivore, and Varanus priscus, the largest lizard known, were formidable predators. Explanations for these extinctions have centered on climatic change or human activities. Here, we review the evidence and arguments for both. Human involvement in the disappearance of some species remains possible but unproven. Mounting evidence points to the loss of most species before the peopling of Sahul (circa 50-45 ka) and a significant role for climate change in the disappearance of the continent's megafauna.

  17. Climate change frames debate over the extinction of megafauna in Sahul (Pleistocene Australia-New Guinea)

    NASA Astrophysics Data System (ADS)

    Wroe, Stephen; Field, Judith H.; Archer, Michael; Grayson, Donald K.; Price, Gilbert J.; Louys, Julien; Faith, J. Tyler; Webb, Gregory E.; Davidson, Iain; Mooney, Scott D.

    2013-05-01

    Around 88 large vertebrate taxa disappeared from Sahul sometime during the Pleistocene, with the majority of losses (54 taxa) clearly taking place within the last 400,000 years. The largest was the 2.8-ton browsing Diprotodon optatum, whereas the ∼100- to 130-kg marsupial lion, Thylacoleo carnifex, the world's most specialized mammalian carnivore, and Varanus priscus, the largest lizard known, were formidable predators. Explanations for these extinctions have centered on climatic change or human activities. Here, we review the evidence and arguments for both. Human involvement in the disappearance of some species remains possible but unproven. Mounting evidence points to the loss of most species before the peopling of Sahul (circa 50-45 ka) and a significant role for climate change in the disappearance of the continent's megafauna.

  18. Molecular signatures of Pleistocene sea-level changes that affected connectivity among freshwater shrimp in Indo-Australian waters.

    PubMed

    De Bruyn, Mark; Mather, Peter B

    2007-10-01

    A major paradigm in evolutionary biology asserts that global climate change during the Pleistocene often led to rapid and extensive diversification in numerous taxa. Recent phylogenetic data suggest that past climatic oscillations may have promoted long-distance marine dispersal in some freshwater crustacea from the Indo-Australian Archipelago (IAA). Whether this pattern is common, and whether similar processes are acting on diversification below the species level is unknown. We used nuclear and mitochondrial molecular variation in a freshwater-dependent decapod crustacean (Macrobrachium rosenbergii), sampled widely from the IAA, to assess the impact of Pleistocene sea-level changes on lineage diversification in this species. Fitting of an isolation with migration model enabled us to reject ongoing migration among lineages, and results indicate that isolation among both mainland-mainland and mainland-island lineages arose during the mid-Pleistocene. Our data suggest a scenario of widespread marine dispersal during Pleistocene glacial maxima (in support of the 'Pleistocene marine dispersal hypothesis') when sea levels were low, and geographical distances between fresh watersheds were greatly reduced, followed by increased isolation as sea levels subsequently rose.

  19. Metagenomic analyses of the late Pleistocene permafrost - additional tools for reconstruction of environmental conditions

    NASA Astrophysics Data System (ADS)

    Rivkina, Elizaveta; Petrovskaya, Lada; Vishnivetskaya, Tatiana; Krivushin, Kirill; Shmakova, Lyubov; Tutukina, Maria; Meyers, Arthur; Kondrashov, Fyodor

    2016-04-01

    A comparative analysis of the metagenomes from two 30 000-year-old permafrost samples, one of lake-alluvial origin and the other from late Pleistocene Ice Complex sediments, revealed significant differences within microbial communities. The late Pleistocene Ice Complex sediments (which have been characterized by the absence of methane with lower values of redox potential and Fe2+ content) showed a low abundance of methanogenic archaea and enzymes from both the carbon and nitrogen cycles, but a higher abundance of enzymes associated with the sulfur cycle. The metagenomic and geochemical analyses described in the paper provide evidence that the formation of the sampled late Pleistocene Ice Complex sediments likely took place under much more aerobic conditions than lake-alluvial sediments.

  20. Global environmental change

    SciTech Connect

    Corell, R.W.; Anderson, P.A.

    1990-01-01

    Fifty years ago the buzz words in science were [open quotes]atomic energy,[close quotes] and the general mood of the public, in those more naive days, was that the earth is so large that it could take any kind of human abuse. The advance of science and technology since then has proved that this is not the case. It is now common sense, even to the layperson, that the earth's environment is delicate and needs careful protection if future generations are to enjoy it. The buzz words now are [open quotes]global change.[close quotes] This book is the outcome of the Workshop on the Science of Global Environmental Change sponsored by the North Atlantic Treaty Organization (NATO) and is one of the NATO's Advanced Science Institute Series books. It is essentially a collection of the lectures given in the workshop. The workshop was apparently not intended for in-depth scientific discussions but to review the overall current research situation and to identify future research needs. Accordingly, the papers collected in this volume are basically of this nature.

  1. American mastodon extirpation in the Arctic and Subarctic predates human colonization and terminal Pleistocene climate change

    PubMed Central

    Zazula, Grant D.; MacPhee, Ross D. E.; Metcalfe, Jessica Z.; Reyes, Alberto V.; Brock, Fiona; Druckenmiller, Patrick S.; Groves, Pamela; Harington, C. Richard; Hodgins, Gregory W. L.; Kunz, Michael L.; Longstaffe, Fred J.; Mann, Daniel H.; McDonald, H. Gregory; Nalawade-Chavan, Shweta; Southon, John R.

    2014-01-01

    Existing radiocarbon (14C) dates on American mastodon (Mammut americanum) fossils from eastern Beringia (Alaska and Yukon) have been interpreted as evidence they inhabited the Arctic and Subarctic during Pleistocene full-glacial times (∼18,000 14C years B.P.). However, this chronology is inconsistent with inferred habitat preferences of mastodons and correlative paleoecological evidence. To establish a last appearance date (LAD) for M. americanum regionally, we obtained 53 new 14C dates on 36 fossils, including specimens with previously published dates. Using collagen ultrafiltration and single amino acid (hydroxyproline) methods, these specimens consistently date to beyond or near the ∼50,000 y B.P. limit of 14C dating. Some erroneously “young” 14C dates are due to contamination by exogenous carbon from natural sources and conservation treatments used in museums. We suggest mastodons inhabited the high latitudes only during warm intervals, particularly the Last Interglacial [Marine Isotope Stage (MIS) 5] when boreal forests existed regionally. Our 14C dataset suggests that mastodons were extirpated from eastern Beringia during the MIS 4 glacial interval (∼75,000 y ago), following the ecological shift from boreal forest to steppe tundra. Mastodons thereafter became restricted to areas south of the continental ice sheets, where they suffered complete extinction ∼10,000 14C years B.P. Mastodons were already absent from eastern Beringia several tens of millennia before the first humans crossed the Bering Isthmus or the onset of climate changes during the terminal Pleistocene. Local extirpations of mastodons and other megafaunal populations in eastern Beringia were asynchrononous and independent of their final extinction south of the continental ice sheets. PMID:25453065

  2. American mastodon extirpation in the Arctic and Subarctic predates human colonization and terminal Pleistocene climate change.

    PubMed

    Zazula, Grant D; MacPhee, Ross D E; Metcalfe, Jessica Z; Reyes, Alberto V; Brock, Fiona; Druckenmiller, Patrick S; Groves, Pamela; Harington, C Richard; Hodgins, Gregory W L; Kunz, Michael L; Longstaffe, Fred J; Mann, Daniel H; McDonald, H Gregory; Nalawade-Chavan, Shweta; Southon, John R

    2014-12-30

    Existing radiocarbon ((14)C) dates on American mastodon (Mammut americanum) fossils from eastern Beringia (Alaska and Yukon) have been interpreted as evidence they inhabited the Arctic and Subarctic during Pleistocene full-glacial times (∼ 18,000 (14)C years B.P.). However, this chronology is inconsistent with inferred habitat preferences of mastodons and correlative paleoecological evidence. To establish a last appearance date (LAD) for M. americanum regionally, we obtained 53 new (14)C dates on 36 fossils, including specimens with previously published dates. Using collagen ultrafiltration and single amino acid (hydroxyproline) methods, these specimens consistently date to beyond or near the ∼ 50,000 y B.P. limit of (14)C dating. Some erroneously "young" (14)C dates are due to contamination by exogenous carbon from natural sources and conservation treatments used in museums. We suggest mastodons inhabited the high latitudes only during warm intervals, particularly the Last Interglacial [Marine Isotope Stage (MIS) 5] when boreal forests existed regionally. Our (14)C dataset suggests that mastodons were extirpated from eastern Beringia during the MIS 4 glacial interval (∼ 75,000 y ago), following the ecological shift from boreal forest to steppe tundra. Mastodons thereafter became restricted to areas south of the continental ice sheets, where they suffered complete extinction ∼ 10,000 (14)C years B.P. Mastodons were already absent from eastern Beringia several tens of millennia before the first humans crossed the Bering Isthmus or the onset of climate changes during the terminal Pleistocene. Local extirpations of mastodons and other megafaunal populations in eastern Beringia were asynchrononous and independent of their final extinction south of the continental ice sheets.

  3. Continuous evolutionary change in Plio-Pleistocene mammals of eastern Africa.

    PubMed

    Bibi, Faysal; Kiessling, Wolfgang

    2015-08-25

    Much debate has revolved around the question of whether the mode of evolutionary and ecological turnover in the fossil record of African mammals was continuous or pulsed, and the degree to which faunal turnover tracked changes in global climate. Here, we assembled and analyzed large specimen databases of the fossil record of eastern African Bovidae (antelopes) and Turkana Basin large mammals. Our results indicate that speciation and extinction proceeded continuously throughout the Pliocene and Pleistocene, as did increases in the relative abundance of arid-adapted bovids, and in bovid body mass. Species durations were similar among clades with different ecological attributes. Occupancy patterns were unimodal, with long and nearly symmetrical origination and extinction phases. A single origination pulse may be present at 2.0-1.75 Ma, but besides this, there is no evidence that evolutionary or ecological changes in the eastern African record tracked rapid, 100,000-y-scale changes in global climate. Rather, eastern African large mammal evolution tracked global or regional climatic trends at long (million year) time scales, while local, basin-scale changes (e.g., tectonic or hydrographic) and biotic interactions ruled at shorter timescales.

  4. Continuous evolutionary change in Plio-Pleistocene mammals of eastern Africa

    PubMed Central

    Bibi, Faysal; Kiessling, Wolfgang

    2015-01-01

    Much debate has revolved around the question of whether the mode of evolutionary and ecological turnover in the fossil record of African mammals was continuous or pulsed, and the degree to which faunal turnover tracked changes in global climate. Here, we assembled and analyzed large specimen databases of the fossil record of eastern African Bovidae (antelopes) and Turkana Basin large mammals. Our results indicate that speciation and extinction proceeded continuously throughout the Pliocene and Pleistocene, as did increases in the relative abundance of arid-adapted bovids, and in bovid body mass. Species durations were similar among clades with different ecological attributes. Occupancy patterns were unimodal, with long and nearly symmetrical origination and extinction phases. A single origination pulse may be present at 2.0–1.75 Ma, but besides this, there is no evidence that evolutionary or ecological changes in the eastern African record tracked rapid, 100,000-y-scale changes in global climate. Rather, eastern African large mammal evolution tracked global or regional climatic trends at long (million year) time scales, while local, basin-scale changes (e.g., tectonic or hydrographic) and biotic interactions ruled at shorter timescales. PMID:26261300

  5. Continuous evolutionary change in Plio-Pleistocene mammals of eastern Africa

    NASA Astrophysics Data System (ADS)

    Bibi, Faysal; Kiessling, Wolfgang

    2015-08-01

    Much debate has revolved around the question of whether the mode of evolutionary and ecological turnover in the fossil record of African mammals was continuous or pulsed, and the degree to which faunal turnover tracked changes in global climate. Here, we assembled and analyzed large specimen databases of the fossil record of eastern African Bovidae (antelopes) and Turkana Basin large mammals. Our results indicate that speciation and extinction proceeded continuously throughout the Pliocene and Pleistocene, as did increases in the relative abundance of arid-adapted bovids, and in bovid body mass. Species durations were similar among clades with different ecological attributes. Occupancy patterns were unimodal, with long and nearly symmetrical origination and extinction phases. A single origination pulse may be present at 2.0-1.75 Ma, but besides this, there is no evidence that evolutionary or ecological changes in the eastern African record tracked rapid, 100,000-y-scale changes in global climate. Rather, eastern African large mammal evolution tracked global or regional climatic trends at long (million year) time scales, while local, basin-scale changes (e.g., tectonic or hydrographic) and biotic interactions ruled at shorter timescales.

  6. Toward an understanding of the Middle Pleistocene Transition as a structural change in climate stability

    NASA Astrophysics Data System (ADS)

    Ditlevsen, Peter

    2016-04-01

    The Middle Pleistocene transition signifies a change approximately 1 Myr ago from a period with 40 kyr glacial cycles to a period of approximately 100 kyr cycles in response to the orbital forcing. This change from the "40 kyr world" to the "100 kyr world" is not reflected in noticeable changes in the forcing. To explain this we present a low order conceptual model for the oscillatory dynamics of the ice sheets in terms of a relaxation oscillator with multiple levels subject to the Milankovitch forcing. The model exhibits smooth transitions between three different climate states; an interglacial (i), a mild glacial (g) and a deep glacial (G) as proposed by Paillard (1998). The model suggests a dynamical explanation in terms of the structure of a slow manifold for the observed allowed and ``forbidden'' transitions between the three climate states. With the model, the pacing of the climate oscillations by the astronomical forcing is through the mechanism of phase-resetting of relaxation oscillations in which the internal phase of the oscillation is affected by the forcing.

  7. Limited hydrologic response to Pleistocene climate change in deep vadose zones — Yucca Mountain, Nevada

    NASA Astrophysics Data System (ADS)

    Paces, James B.; Neymark, Leonid A.; Whelan, Joseph F.; Wooden, Joseph L.; Lund, Steven P.; Marshall, Brian D.

    2010-12-01

    Understanding the movement of water through thick vadose zones, especially on time scales encompassing long-term climate change, is increasingly important as societies utilize semi-arid environments for both water resources and sites viewed as favorable for long-term disposal or storage of hazardous waste. Hydrologic responses to Pleistocene climate change within a deep vadose zone in the eastern Mojave Desert at Yucca Mountain, Nevada, were evaluated by uranium-series dating of finely layered hyalitic opal using secondary ion mass spectrometry. Opal is present within cm-thick secondary hydrogenic mineral crusts coating floors of lithophysal cavities in fractured volcanic rocks at depths of 200 to 300 m below land surface. Uranium concentrations in opal fluctuate systematically between 5 and 550 μg/g. Age-calibrated profiles of uranium concentration correlate with regional climate records over the last 300,000 years and produce time-series spectral peaks that have distinct periodicities of 100- and 41-ka, consistent with planetary orbital parameters. These results indicate that the chemical compositions of percolating solutions varied in response to near-surface, climate-driven processes. However, slow (micrometers per thousand years), relatively uniform growth rates of secondary opal and calcite deposition spanning several glacial-interglacial climate cycles imply that water fluxes in the deep vadose zone remained low and generally buffered from the large fluctuations in available surface moisture during different climates.

  8. Lacustrine chronology links late Pleistocene climate change and mass movements in northern New Mexico

    SciTech Connect

    Dethier, D.P.; Reneau, S.L.

    1996-06-01

    Well-dated lacustrine deposits in northern White Rock Canyon, New Mexico, record damming of the Rio Grande by at least four separate failures of a slump complex between about 17.5 and 12.4 ka ({sup 14}C), linking mass movements to a period of rapid climate change in the western United States. Failure of metastable slumps probably resulted from removal of lateral support during down-cutting and erosion by the Rio Grande and from a decrease in resisting forces due to increased pore pressures. Our chronology suggests that the lake that formed between 17.5 and 15.0 ka may record effects of both glacial melt and pluvial activity (mainly enhanced rainfall); the youngest lake (neary 12.4 ka) may record pluvial runoff; and the intermediate lakes (13.7 to 13.1 ka) may record pluvial and minor melt-water activity. We have not found lacustrine deposits younger than about 12.4 ka. The record of geomorphic response along the Rio Grande suggests that late Pleistocene climatic changes may have triggered similar mass movements elsewhere in the southwest. 27 refs., 4 figs.

  9. Pleistocene geomorphology and geochronology of eastern Grand Canyon: linkages of landscape components during climate changes

    NASA Astrophysics Data System (ADS)

    Anders, Matt D.; Pederson, Joel L.; Rittenour, Tammy M.; Sharp, Warren D.; Gosse, John C.; Karlstrom, Karl E.; Crossey, Laura J.; Goble, Ronald J.; Stockli, Lisa; Yang, Guang

    2005-12-01

    We report new mapping, soils, survey, and geochronologic (luminescence, U-series, and cosmogenic-nuclide) data from Pleistocene deposits in the arid setting of eastern Grand Canyon. The result is a stratigraphic framework of inset fill gravels and associated terraces that provide a record of the responses of hillslopes, tributary streams, and the Colorado River to the last ˜400 kyr of glacial-interglacial climate change. The best-preserved last 80 kyr of this record indicates a stratigraphic-chronologic disconnect between both deposition and incision along the Colorado River versus along the trunks of local tributaries. For example, the Colorado River finished aggrading and had already begun incising before the main pulse of aggradation in the trunks of local catchments during Marine Isotope Stage 3, and then tributary incision followed during the millennial-scale fluctuations of the last glacial epoch, potentially concurrent with mainstem aggradation. The mainstem record appears to broadly correlate with regional paleoclimate and upstream geomorphic records and thus may be responding to climatic-hydrologic changes in its mountain headwaters, with aggradation beginning during full-glacial times and continuing into subsequent interglacials. The contrasting lag time in responses of the dryland catchments within Grand Canyon may be largely a function of the weathering-limited nature of hillslope sediment supply.

  10. Limited hydrologic response to Pleistocene climate change in deep vadose zones - Yucca Mountain, Nevada

    USGS Publications Warehouse

    Paces, J.B.; Neymark, L.A.; Whelan, J.F.; Wooden, J.L.; Lund, S.P.; Marshall, B.D.

    2010-01-01

    Understanding the movement of water through thick vadose zones, especially on time scales encompassing long-term climate change, is increasingly important as societies utilize semi-arid environments for both water resources and sites viewed as favorable for long-term disposal or storage of hazardous waste. Hydrologic responses to Pleistocene climate change within a deep vadose zone in the eastern Mojave Desert at Yucca Mountain, Nevada, were evaluated by uranium-series dating of finely layered hyalitic opal using secondary ion mass spectrometry. Opal is present within cm-thick secondary hydrogenic mineral crusts coating floors of lithophysal cavities in fractured volcanic rocks at depths of 200 to 300 m below land surface. Uranium concentrations in opal fluctuate systematically between 5 and 550 μg/g. Age-calibrated profiles of uranium concentration correlate with regional climate records over the last 300,000 years and produce time-series spectral peaks that have distinct periodicities of 100- and 41-ka, consistent with planetary orbital parameters. These results indicate that the chemical compositions of percolating solutions varied in response to near-surface, climate-driven processes. However, slow (micrometers per thousand years), relatively uniform growth rates of secondary opal and calcite deposition spanning several glacial–interglacial climate cycles imply that water fluxes in the deep vadose zone remained low and generally buffered from the large fluctuations in available surface moisture during different climates.

  11. Contrasting response to Pleistocene climate change by ground-living and arboreal Mandarina snails from the oceanic Hahajima archipelago.

    PubMed

    Davison, Angus; Chiba, Satoshi

    2008-10-27

    While the genetic impact of Pleistocene climate change on temperate species has been well characterized, especially in Europe and North America, an effect on the diversification of species on oceanic islands has been less well studied. This is perhaps a surprising observation given the traditional and continuing contribution of island species (e.g. Darwin's finches, Partula snails, Lord Howe Island palms) to understand speciation. Here, we combine mitochondrial and microsatellite data from the ground-living and arboreal Mandarina snails of the oceanic, subtropical Hahajima archipelago (Ogasawara, colloquially 'Galápagos of the Orient') to enable a comparative approach to understand the impact of the Pleistocene glaciations on their phylogeography. Prior work suggested that several narrowly divergent, ground-living species pairs of Mandarina populations on the outlying islands, as well as the low-lying southern and central parts of Hahajima, probably underwent bottlenecks and subsequent expansions during the recent Pleistocene. Here, the most striking finding is that largely arboreal species have deeply divergent, geographically restricted mitochondrial lineages, in contrast to a census size that is at least an order of magnitude lower than ground-living snails. As populations of both types are highly polymorphic at microsatellite loci, the systematic difference at the mitochondrial locus probably indicates a contrasting effect of the Pleistocene climate cycles on the two groups. We speculate that this may have partly come about owing to a reduced efficacy of natural selection on the more greatly structured populations of arboreal snails. If so, then a prediction is that the genome of other snails, or other species with limited mobility, will show a similar response to the Pleistocene climate cycles.

  12. Amphibian DNA shows marked genetic structure and tracks pleistocene climate change in northeastern Brazil.

    PubMed

    Carnaval, Ana Carolina; Bates, John M

    2007-12-01

    The glacial refugia paradigm has been broadly applied to patterns of species dynamics and population diversification. However, recent geological studies have demonstrated striking Pleistocene climate changes in currently semiarid northeastern Brazil at time intervals much more frequent than the climatic oscillations associated with glacial and interglacial periods. These geomorphic data documented recurrent pulses of wet regimes in the past 210,000 years that correlate with climate anomalies affecting multiple continents. While analyzing DNA sequences of two mitochondrial genes (cytochrome b and NADH-dehydrogenase subunit 2) and one nuclear marker (cellular-myelocytomatosis proto-oncogene) in the forest-associated frogs Proceratophrys boiei and Ischnocnema gr. ramagii, we found evidence of biological responses consistent with these pluvial maxima events. Sampled areas included old, naturally isolated forest enclaves within the semiarid Caatinga, as well as recent man-made fragments of humid coastal Atlantic forest. Results show that mtDNA lineages in enclave populations are monophyletic or nearly so, whereas nonenclave populations are polyphyletic and more diverse. The studied taxa show evidence of demographic expansions at times that match phases of pluvial maxima inferred from geological data. Divergence times between several populations fall within comparatively drier intervals suggested by geomorphology. Mitochondrial and nuclear data show local populations to be genetically structured, with some high levels of differentiation that suggest the need of further taxonomic work.

  13. The impact of climate change on the structure of Pleistocene food webs across the mammoth steppe

    PubMed Central

    Yeakel, Justin D.; Guimarães, Paulo R.; Bocherens, Hervé; Koch, Paul L.

    2013-01-01

    Species interactions form food webs, impacting community structure and, potentially, ecological dynamics. It is likely that global climatic perturbations that occur over long periods of time have a significant influence on species interaction patterns. Here, we integrate stable isotope analysis and network theory to reconstruct patterns of trophic interactions for six independent mammalian communities that inhabited mammoth steppe environments spanning western Europe to eastern Alaska (Beringia) during the Late Pleistocene. We use a Bayesian mixing model to quantify the contribution of prey to the diets of local predators, and assess how the structure of trophic interactions changed across space and the Last Glacial Maximum (LGM), a global climatic event that severely impacted mammoth steppe communities. We find that large felids had diets that were more constrained than those of co-occurring predators, and largely influenced by an increase in Rangifer abundance after the LGM. Moreover, the structural organization of Beringian and European communities strongly differed: compared with Europe, species interactions in Beringian communities before—and possibly after—the LGM were highly modular. We suggest that this difference in modularity may have been driven by the geographical insularity of Beringian communities. PMID:23658198

  14. The impact of climate change on the structure of Pleistocene food webs across the mammoth steppe.

    PubMed

    Yeakel, Justin D; Guimarães, Paulo R; Bocherens, Hervé; Koch, Paul L

    2013-07-07

    Species interactions form food webs, impacting community structure and, potentially, ecological dynamics. It is likely that global climatic perturbations that occur over long periods of time have a significant influence on species interaction patterns. Here, we integrate stable isotope analysis and network theory to reconstruct patterns of trophic interactions for six independent mammalian communities that inhabited mammoth steppe environments spanning western Europe to eastern Alaska (Beringia) during the Late Pleistocene. We use a Bayesian mixing model to quantify the contribution of prey to the diets of local predators, and assess how the structure of trophic interactions changed across space and the Last Glacial Maximum (LGM), a global climatic event that severely impacted mammoth steppe communities. We find that large felids had diets that were more constrained than those of co-occurring predators, and largely influenced by an increase in Rangifer abundance after the LGM. Moreover, the structural organization of Beringian and European communities strongly differed: compared with Europe, species interactions in Beringian communities before--and possibly after--the LGM were highly modular. We suggest that this difference in modularity may have been driven by the geographical insularity of Beringian communities.

  15. Epigenetic variation and environmental change.

    PubMed

    Meyer, Peter

    2015-06-01

    Environmental conditions can change the activity of plant genes via epigenetic effects that alter the competence of genetic information to be expressed. This may provide a powerful strategy for plants to adapt to environmental change. However, as epigenetic changes do not modify DNA sequences and are therefore reversible, only those epi-mutations that are transmitted through the germline can be expected to contribute to a long-term adaptive response. The major challenge for the investigation of epigenetic adaptation theories is therefore to identify genomic loci that undergo epigenetic changes in response to environmental conditions, which alter their expression in a heritable way and which improve the plant's ability to adapt to the inducing conditions. This review focuses on the role of DNA methylation as a prominent epigenetic mark that controls chromatin conformation, and on its potential in mediating expression changes in response to environmental signals.

  16. Environmental evolutions of the Alzette valley (Grand Duchy of Luxembourg) since Late Pleistocene

    NASA Astrophysics Data System (ADS)

    Naton, H.-G.; Ruffaldi, P.; Meyrick, R.; Maquil, R.; Colbach, R.; Kausch, B.; Baes, R.; Stead, A.; Le Brun-Ricalens, F.; Brou, L.; Schoellen, A.

    2009-04-01

    The Alzette River rises within France, approximately 4 km south of the French-Luxembourg border, and has a total length of 73 kilometres before joining the Sauer which is a left-bank tributary of the Moselle River. During the construction of the "Nordstrooss" motorway (going north from Luxembourg city towards Ettelbruck) a viaduct was built that crosses the wide alluvial plain (about 1 km) of the Alzette River valley near Lorentzweiler. A lot of drillings were also made for geotechnical purposes by the Geological survey of Luxembourg (SGL). The drillings were able to provide informations about the sediments preserved in the Alzette River valley floor. This information has allowed the construction of a cross-profile through the valley showing the stratigraphy of the quaternary deposits, and illustrating that it was the result of a rather complex evolution (aggradation and incision periods leading to terraces formation, input of slope deposits at the valley margins, possible eolian input, …). A multidisciplinary research project thus started, aiming to reconstruct the paleoenvironment of the Alzette region during the late Pleistocene and Holocene periods. The drilling results make it possible to reconstruct the geometry of the quaternary sedimentary units of the Alzette valley. Three stepped alluvial units are recognized along the cross profile: the lower one (Az0) corresponds with the maximal incision of the Alzette. It is preserved in the western part of the floodplain, with base being located at about 212 m a.s.l.. In the eastern part of the valley the contact between the fluvial deposits and the substratum is located at about 215 m a.s.l.: these deposits may also be allocated to a lower terrace Az1 (relative height : +3 m). A third alluvial unit Az2 was recognized in two drillings, with bedrock located at about 224 m a.s.l. (+12 m). The channel migration in the valley and the assumed meandering dynamics (suggested by the weakness of the longitudinal slope) led

  17. Thermohaline Circulation Crisis and Changes Through the Mid-Pleistocene Transition

    NASA Astrophysics Data System (ADS)

    Goldstein, S. L.; Pena, L.

    2013-12-01

    The Mid-Pleistocene Transition (MPT) marked a fundamental change in glacial-interglacial periodicity, transitioning from ~41,000 to 100,000 year cycles, accompanied by higher amplitude climate variability. It occurred without a significant change in orbital forcing, and thus its causes are poorly understood. We report major changes in the pre- and post-MPT mode of the ocean thermohaline circulation (THC), and a THC crisis during the MPT, from Nd isotopes in ODP Sites 1088 (~42S, 2082m) and 1090 (~43S, 3702m). The core locations are at the transition between the South Atlantic and the Southern oceans, a major gateway for the exchange of northern- and southern-sourced water masses. The new data show that in the ';40-kyr world' prior to the MPT, NADW export was strong during both interglacials and glacials. At ~900 ka the THC system underwent a major crisis, with an unprecedented weakening in NADW export during Marine Isotope Stages (MIS) 22-24. The recovery of the THC system in the post-MPT ';100-kyr world' is characterized by strong THC during interglacials, similar to pre-MPT interglacials, but much weaker THC during glacials. The ';THC crisis' interval includes MIS 23, which is unique as an interglacial where the THC operated in the same weak mode as post-MPT glacials. The MIS 22-24 interval has been recognized as a time of abrupt atmospheric pCO2 drawdown (Hoenisch et al. 2009) and significant cooling of ocean deep water, and Antarctic ice sheet expansion (Elderfield et al. Science 2012). Our data indicate that THC changes played an important role as a primary driving force, and helped to generate a series of positive feedbacks. This drastic change in deep-ocean circulation had important implications for the coeval drawdown of atmospheric pCO2, and the absence of a strong THC system through a glacial-to-interglacial-to-glacial cycle had a major impact on high latitude ice sheet growth. We suggest that the weak NADW export during MIS 24-22 resulted in reduced

  18. Peripatric speciation of an endemic species driven by Pleistocene climate change: The case of the Mexican prairie dog (Cynomys mexicanus).

    PubMed

    Castellanos-Morales, Gabriela; Gámez, Niza; Castillo-Gámez, Reyna A; Eguiarte, Luis E

    2016-01-01

    The hypothesis that endemic species could have originated by the isolation and divergence of peripheral populations of widespread species can be tested through the use of ecological niche models (ENMs) and statistical phylogeography. The joint use of these tools provides complementary perspectives on historical dynamics and allows testing hypotheses regarding the origin of endemic taxa. We used this approach to infer the historical processes that have influenced the origin of a species endemic to the Mexican Plateau (Cynomys mexicanus) and its divergence from a widespread ancestor (Cynomys ludovicianus), and to test whether this endemic species originated through peripatric speciation. We obtained genetic data for 295 individuals for two species of black-tailed prairie dogs (C. ludovicianus and C. mexicanus). Genetic data consisted of mitochondrial DNA sequences (cytochrome b and control region), and 10 nuclear microsatellite loci. We estimated dates of divergence between species and between lineages within each species and performed ecological niche modelling (Present, Last Glacial Maximum and Last Interglacial) to determine changes in the distribution range of both species during the Pleistocene. Finally, we used Bayesian inference methods (DIYABC) to test different hypotheses regarding the divergence and demographic history of these species. Data supported the hypothesis of the origin of C. mexicanus from a peripheral population isolated during the Pleistocene [∼230,000 years ago (0.1-0.43 Ma 95% HPD)], with a Pleistocene-Holocene (∼9,000-11,000 years ago) population expansion (∼10-fold increase in population size). We identified the presence of two possible refugia in the southern area of the distribution range of C. ludovicianus and another, consistent with the distribution range of C. mexicanus. Our analyses suggest that Pleistocene climate change had a strong impact in the distribution of these species, promoting peripatric speciation for the origin of

  19. Late Pleistocene and Holocene environmental history of the Iguala Valley, Central Balsas Watershed of Mexico.

    PubMed

    Piperno, D R; Moreno, J E; Iriarte, J; Holst, I; Lachniet, M; Jones, J G; Ranere, A J; Castanzo, R

    2007-07-17

    The origin of agriculture was a signal development in human affairs and as such has occupied the attention of scholars from the natural and social sciences for well over a century. Historical studies of climate and vegetation are closely associated with crop plant evolution because they can reveal the ecological contexts of plant domestication together with the antiquity and effects of agricultural practices on the environment. In this article, we present paleoecological evidence from three lakes and a swamp located in the Central Balsas watershed of tropical southwestern Mexico that date from 14,000 B.P. to the modern era. [Dates expressed in B.P. years are radiocarbon ages. Calibrated (calendar) ages, expressed as cal B.P., are provided for dates in the text.] Previous molecular studies suggest that maize (Zea mays L.) and other important crops such as squashes (Cucurbita spp.) were domesticated in the region. Our combined pollen, phytolith, charcoal, and sedimentary studies indicate that during the late glacial period (14,000-10,000 B.P.), lake beds were dry, the climate was cooler and drier, and open vegetational communities were more widespread than after the Pleistocene ended. Zea was a continuous part of the vegetation since at least the terminal Pleistocene. During the Holocene, lakes became important foci of human activity, and cultural interference with a species-diverse tropical forest is indicated. Maize and squash were grown at lake edges starting between 10,000 and 5,000 B.P., most likely sometime during the first half of that period. Significant episodes of climatic drying evidenced between 1,800 B.P. and 900 B.P. appear to be coeval with those documented in the Classic Maya region and elsewhere, showing widespread instability in the late Holocene climate.

  20. Late Pleistocene and Holocene environmental history of the Iguala Valley, Central Balsas Watershed of Mexico

    PubMed Central

    Piperno, D. R.; Moreno, J. E.; Iriarte, J.; Holst, I.; Lachniet, M.; Jones, J. G.; Ranere, A. J.; Castanzo, R.

    2007-01-01

    The origin of agriculture was a signal development in human affairs and as such has occupied the attention of scholars from the natural and social sciences for well over a century. Historical studies of climate and vegetation are closely associated with crop plant evolution because they can reveal the ecological contexts of plant domestication together with the antiquity and effects of agricultural practices on the environment. In this article, we present paleoecological evidence from three lakes and a swamp located in the Central Balsas watershed of tropical southwestern Mexico that date from 14,000 B.P. to the modern era. [Dates expressed in B.P. years are radiocarbon ages. Calibrated (calendar) ages, expressed as cal B.P., are provided for dates in the text.] Previous molecular studies suggest that maize (Zea mays L.) and other important crops such as squashes (Cucurbita spp.) were domesticated in the region. Our combined pollen, phytolith, charcoal, and sedimentary studies indicate that during the late glacial period (14,000–10,000 B.P.), lake beds were dry, the climate was cooler and drier, and open vegetational communities were more widespread than after the Pleistocene ended. Zea was a continuous part of the vegetation since at least the terminal Pleistocene. During the Holocene, lakes became important foci of human activity, and cultural interference with a species-diverse tropical forest is indicated. Maize and squash were grown at lake edges starting between 10,000 and 5,000 B.P., most likely sometime during the first half of that period. Significant episodes of climatic drying evidenced between 1,800 B.P. and 900 B.P. appear to be coeval with those documented in the Classic Maya region and elsewhere, showing widespread instability in the late Holocene climate. PMID:17537917

  1. Middle to Late Pleistocene vegetation and climate change in subtropical southern East Africa

    NASA Astrophysics Data System (ADS)

    Castañeda, Isla S.; Caley, Thibaut; Dupont, Lydie; Kim, Jung-Hyun; Malaizé, Bruno; Schouten, Stefan

    2016-09-01

    In this study we investigate Pleistocene vegetation and climate change in southern East Africa by examining plant leaf waxes in a marine sediment core that receives terrestrial runoff from the Limpopo River. The plant leaf wax records are compared to a multi-proxy sea surface temperature (SST) record and pollen assemblage data from the same site. We find that Indian Ocean SST variability, driven by high-latitude obliquity, exerted a strong control on the vegetation of southern East Africa during the past 800,000 yr. Interglacial periods were characterized by relatively wetter and warmer conditions, increased contributions of C3 vegetation, and higher SST, whereas glacial periods were marked by cooler and arid conditions, increased contributions of C4 vegetation, and lower SST. We find that Marine Isotope Stages (MIS) 5e, 11c, 15e and 7a-7c are strongly expressed in the plant leaf wax records but MIS 7e is absent while MIS 9 is rather weak. Our plant leaf wax records also record the climate transition associated with the Mid-Brunhes Event (MBE) suggesting that the pre-MBE interval (430-800 ka) was characterized by higher inputs from grasses in comparison to relatively higher inputs from trees in the post-MBE interval (430 to 0 ka). Differences in vegetation and SST of southern East Africa between the pre- and post-MBE intervals appear to be related to shifts in the location of the Subtropical Front. Comparison with vegetation records from tropical East Africa indicates that the vegetation of southern East Africa, while exhibiting glacial-interglacial variability and notable differences between the pre- and post-MBE portions of the record, likely did not experience such dramatic extremes as occurred to the north at Lake Malawi.

  2. The influence of sea-level changes on tropical coastal lowlands; the Pleistocene Coropina Formation, Suriname

    NASA Astrophysics Data System (ADS)

    Wong, Th. E.; de Kramer, R.; de Boer, P. L.; Langereis, C.; Sew-A-Tjon, J.

    2009-04-01

    The Pleistocene Coropina Formation largely constitutes the Old Coastal Plain of Suriname. It is exposed fully only in open-pit bauxite mines in the central coastal plain as part of the unconsolidated overburden of Paleocene-Eocene bauxites. This study deals with the stratigraphy, sedimentology and chronology of this formation, and is based on a study in the recently closed Lelydorp-III bauxite mine operated by N.V. BHP Billiton Maatschappij Suriname. The Coropina Formation consists of the Para and Lelydorp Members. We present a detailed lithological subdivision of these members. In the Para Member, four units are discerned which are grouped in two transgressive cycles, both ranging upward from terrestrial towards chenier and coastal mudflat deposits reflecting glacio-eustatic sea-level changes. The sandy sediments represent fluviatile and beach-bar (chenier) deposits, and were supplied by rivers from the Precambrian basement and to a lesser extent by westward longshore coastal drift. Clays, largely derived from the Amazon River and transported alongshore over the shelf, were deposited in extensive coastal mudflats. The Lelydorp Member, also comprising four units, represents a depositional system that is closely comparable to the recent Suriname coastal setting, i.e., a lateral and vertical alternation of mudflat and chenier deposits formed over a period characterised by more or less constant sea level. Palaeomagnetic data indicate a dominantly reversed magnetic polarity in the Para Member, whereas the Lelydorp Member shows a normal magnetic polarity with a minor reversed polarity overprint. The reversed polarities of the Para Member exclude a Brunhes Chron (0.78-0.0 Ma) age, and thus assign it to the Matuyama Chron (2.58-0.78 Ma). This implies that the Coropina Formation is much older than hitherto assumed, and that one or more (long-term) hiatuses are not recognizable in the lithological succession.

  3. Environmental changes and violent conflict

    NASA Astrophysics Data System (ADS)

    Bernauer, Thomas; Böhmelt, Tobias; Koubi, Vally

    2012-03-01

    This letter reviews the scientific literature on whether and how environmental changes affect the risk of violent conflict. The available evidence from qualitative case studies indicates that environmental stress can contribute to violent conflict in some specific cases. Results from quantitative large-N studies, however, strongly suggest that we should be careful in drawing general conclusions. Those large-N studies that we regard as the most sophisticated ones obtain results that are not robust to alternative model specifications and, thus, have been debated. This suggests that environmental changes may, under specific circumstances, increase the risk of violent conflict, but not necessarily in a systematic way and unconditionally. Hence there is, to date, no scientific consensus on the impact of environmental changes on violent conflict. This letter also highlights the most important challenges for further research on the subject. One of the key issues is that the effects of environmental changes on violent conflict are likely to be contingent on a set of economic and political conditions that determine adaptation capacity. In the authors' view, the most important indirect effects are likely to lead from environmental changes via economic performance and migration to violent conflict.

  4. New carbon dates link climatic change with human colonization and Pleistocene extinctions.

    PubMed

    Guthrie, R Dale

    2006-05-11

    Drastic ecological restructuring, species redistribution and extinctions mark the Pleistocene-Holocene transition, but an insufficiency of numbers of well-dated large mammal fossils from this transition have impeded progress in understanding the various causative links. Here I add many new radiocarbon dates to those already published on late Pleistocene fossils from Alaska and the Yukon Territory (AK-YT) and show previously unrecognized patterns. Species that survived the Pleistocene, for example, bison (Bison priscus, which evolved into Bison bison), wapiti (Cervus canadensis) and, to a smaller degree, moose (Alces alces), began to increase in numbers and continued to do so before and during human colonization and before the regional extinction of horse (Equus ferus) and mammoth (Mammuthus primigenius). These patterns allow us to reject, at least in AK-YT, some hypotheses of late Pleistocene extinction: 'Blitzkrieg' version of simultaneous human overkill, 'keystone' removal, and 'palaeo-disease'. Hypotheses of a subtler human impact and/or ecological replacement or displacement are more consistent with the data. The new patterns of dates indicate a radical ecological sorting during a uniquely forage-rich transitional period, affecting all large mammals, including humans.

  5. Multiple instabilities and modes of glacial rhythmicity in the Plio-Pleistocene: A general theory of late Cenozoic climatic change

    SciTech Connect

    Saltzman, B.; Verbitsky, M.Ya.

    1993-10-01

    Several distinct modes of glacial oscillation have existed during the past few million years, ranging from low-amplitude, high-frequency oscillations in the early Pliocene, through relatively high amplitude, predominantly near 40 ky period, oscillations in the late Pliocene and early Pleistocene, to the major near 100 ky period oscillations of the late Pleistocene. In addition to other plausible mechanisms, this study illustrates another possible contributor based on the hypothesis that the slow-response climatic system is bistable and that two kinds of internal instability may be operative along with externally imposed forcing due to earth-orbital (Milankovitch) radiation changes and slow, tectonically-induced changes in atmospheric carbon dioxide. Within the framework of a dynamical model containing the possibility for these two instabilities, as well as for stable modes, the study shows (1) how Milankovitch radiative changes or stochastic forcing influencing ice sheets can induce aperiodic (chaotic) transitions between the possible stable and unstable modes, and (2) how progressive, long-term, tectonically-induced, changes in carbon dioxide, acting in concert with earth-orbital radiative variations in high Northern Hemisphere latitudes, can force systematic transitions between the modes. This is a minimum dynamical model of the late Cenozoic climatic changes, containing the main physical factors determining these changes: ice mass, bedrock depression, atmospheric carbon dioxide concentration, deep ocean thermohaline state, Milankovitch radiation forcing, and slow tectonically-induced carbon dioxide forcing. 34 refs., 13 figs., 2 tabs.

  6. Late Pleistocene environmental fluctuations in Taiwan southwestern plain with constraints of the analyses on organic carbon

    NASA Astrophysics Data System (ADS)

    Chiang, H.; Chen, Y.

    2003-12-01

    Taiwan is located at the junction point between the Philippine Sea and Eurasian plate, where the Asian monsoon is supposed as the most important factor in controlling the regional climate. Due to the high subsidence rate caused by westerly moving thrust sheet, sedimentary sequences of late Quaternary overlying on the Tertiary basement in coastal plain are usually over 300 meters. The isotopic composition of organic carbon has been reported to preserve the syn-depositional signals for source identification derived from two major sources, the terrestrial plants and marine organisms. Except for the extreme region, the terrestrial plants can be roughly divided into C3 and C4 plants in modern world. Since they adopt different photosynthesis processes, each of them shows specific δ 13C values. As literatures the δ 13C values of organic matters in marine sediments are relatively constant in a local area. On the other hand, the concentrations of total organic carbon (TOC) preserved in sediments can also reflect the experienced paleo-environment. For instance, an anoxic environment, such as a lagoon or marsh will usually preserve high TOC. Consequently, the elemental abundance and corresponding isotopes of organic carbon are wildly used as proxies to retrieve sedimentary environment and vegetation changes. For the purpose of high resolution, i.e., every 3 to 4m, we sampled cores drilled in coastal plain of southwestern Taiwan and conducted carbon isotope analysis to diagnose the detailed environmental changes under the major framework-global change. As our results, TOC values remain in a relatively stable and low level when the corresponding δ 13C data indicate marine organic source, while the terrestrial source usually causes undulated TOC. On the other hand, based on the isotopic data measured in the lower part of the core, the study area was inundated by sea-water as a result of the high sea-stand of MIS (marine isotope stage) 5. Subsequently, the climate turned to

  7. The response of vegetation on the Andean flank in western Amazonia to Pleistocene climate change.

    PubMed

    Cárdenas, Macarena L; Gosling, William D; Sherlock, Sarah C; Poole, Imogen; Pennington, R Toby; Mothes, Patricia

    2011-02-25

    A reconstruction of past environmental change from Ecuador reveals the response of lower montane forest on the Andean flank in western Amazonia to glacial-interglacial global climate change. Radiometric dating of volcanic ash indicates that deposition occurred ~324,000 to 193,000 years ago during parts of Marine Isotope Stages 9, 7, and 6. Fossil pollen and wood preserved within organic sediments suggest that the composition of the forest altered radically in response to glacial-interglacial climate change. The presence of Podocarpus macrofossils ~1000 meters below the lower limit of their modern distribution indicates a relative cooling of at least 5°C during glacials and persistence of wet conditions. Interglacial deposits contain thermophilic palms suggesting warm and wet climates. Hence, global temperature change can radically alter vegetation communities and biodiversity in this region.

  8. Last straw versus Blitzkrieg overkill: Climate-driven changes in the Arctic Siberian mammoth population and the Late Pleistocene extinction problem

    NASA Astrophysics Data System (ADS)

    Nikolskiy, P. A.; Sulerzhitsky, L. D.; Pitulko, V. V.

    2011-08-01

    A set of radiocarbon dates on woolly mammoth were obtained from several regions of Arctic Siberia: the New Siberian Islands ( n = 68), north of the Yana-Indigirka Lowland ( n = 43), and the Taimyr Peninsula ( n = 18). Based on these and earlier published dates ( n = 201) from the East Arctic, a comparative analysis of the time-related density distribution of 14C dates was conducted. It was shown that the frequencies of 14C dates under certain conditions reflect temporal fluctuations in mammoth numbers. At the end of the Pleistocene the number of mammoths in the East Arctic changed in a cyclic manner in keeping with a general "Milankovitch-like" trend. The fluctuations in numbers at the end of the Pleistocene occurred synchronously with paleoenvironmental changes controlled by global climatic change. There were three minima of relative mammoth numbers during the last 50 000 years: 22 000, 14 500-19 000, and 9500 radiocarbon years ago, or around 26 000, 16-20 000, and 10 500 calendar years respectively. The last mammoths lived on the New Siberian Islands, which were connected to the continent at that time, 9470 ± 40 radiocarbon years ago (10 700 ± 70 calendar years BP). This new youngest date approximates the extinction time of mammoths in the last continental refugium of the Holarctic. The adverse combination of environmental parameters was apparently a major factor in the critical reduction in mammoth numbers. The dispersal of humans into the Arctic areas of Siberia no later than 28 000 radiocarbon years ago did not overtly influence animal numbers. Humans were not responsible for the destruction of a sustainable mammoth population. The expanding human population could have become fatal to mammoths during strong the minima of their numbers, one of which occurred at the very beginning of the Holocene.

  9. Late Pleistocene dune activity in the central Great Plains, USA

    USGS Publications Warehouse

    Mason, J.A.; Swinehart, J.B.; Hanson, P.R.; Loope, D.B.; Goble, R.J.; Miao, X.; Schmeisser, R.L.

    2011-01-01

    Stabilized dunes of the central Great Plains, especially the megabarchans and large barchanoid ridges of the Nebraska Sand Hills, provide dramatic evidence of late Quaternary environmental change. Episodic Holocene dune activity in this region is now well-documented, but Late Pleistocene dune mobility has remained poorly documented, despite early interpretations of the Sand Hills dunes as Pleistocene relicts. New optically stimulated luminescence (OSL) ages from drill cores and outcrops provide evidence of Late Pleistocene dune activity at sites distributed across the central Great Plains. In addition, Late Pleistocene eolian sands deposited at 20-25 ka are interbedded with loess south of the Sand Hills. Several of the large dunes sampled in the Sand Hills clearly contain a substantial core of Late Pleistocene sand; thus, they had developed by the Late Pleistocene and were fully mobile at that time, although substantial sand deposition and extensive longitudinal dune construction occurred during the Holocene. Many of the Late Pleistocene OSL ages fall between 17 and 14 ka, but it is likely that these ages represent only the later part of a longer period of dune construction and migration. At several sites, significant Late Pleistocene or Holocene large-dune migration also probably occurred after the time represented by the Pleistocene OSL ages. Sedimentary structures in Late Pleistocene eolian sand and the forms of large dunes potentially constructed in the Late Pleistocene both indicate sand transport dominated by northerly to westerly winds, consistent with Late Pleistocene loess transport directions. Numerical modeling of the climate of the Last Glacial Maximum has often yielded mean monthly surface winds southwest of the Laurentide Ice Sheet that are consistent with this geologic evidence, despite strengthened anticyclonic circulation over the ice sheet. Mobility of large dunes during the Late Pleistocene on the central Great Plains may have been the result of

  10. A first calibration of nonmarine ostracod species for the quantitative estimation of Pleistocene climate change in southern Africa

    NASA Astrophysics Data System (ADS)

    Horne, D. J.; Martens, K.

    2009-04-01

    Although qualitative statements have been made about general climatic conditions in southern Africa during the Pleistocene, there are few quantifiable palaeoclimatic data based on field evidence, especially regarding whether the area was wetter or drier during the Last Glacial Maximum. Such information is critical in validating models of climate change, both in spatial and temporal dimensions. As an essential preliminary step towards palaeoclimate reconstructions using fossil ostracods from cored lake sediment sequences, we have calibrated a training set of living ostracod species' distributions against a modern climate dataset and other available environmental data. The modern ostracod dataset is based on the collections in the Royal Belgian Institute of Natural Sciences in Brussels, which constitutes the most diverse and comprehensive collection of southern African nonmarine ostracods available anywhere in the world. To date, c. 150 nominal species have been described from southern Africa (Martens, 2001) out of c. 450 species in the total Afrotropical area (Martens et al., 2008). Here we discuss the potential value and limitations of the training set for the estimation of past climatic parameters including air temperature (July and January means, maxima and minima, Mean Annual Air Temperature), precipitation, water conductivity and pH. The next step will be to apply the Mutual Ostracod Temperature Range method (Horne, 2007; Horne & Mezquita, 2008) to the palaeoclimatic analysis of fossil ostracod assemblages from sequences recording the Last Glacial Maximum in southern Africa. Ultimately this work will contribute to the development of a glacier-climate modelling project based on evidence of former niche glaciation of the Drakensberg Escarpment. Horne, D. J. 2007. A Mutual Temperature Range method for Quaternary palaeoclimatic analysis using European nonmarine Ostracoda. Quaternary Science Reviews, 26, 1398-1415. Horne, D. J. & Mezquita, F. 2008. Palaeoclimatic

  11. Environmental change in moorland landscapes

    NASA Astrophysics Data System (ADS)

    Holden, J.; Shotbolt, L.; Bonn, A.; Burt, T. P.; Chapman, P. J.; Dougill, A. J.; Fraser, E. D. G.; Hubacek, K.; Irvine, B.; Kirkby, M. J.; Reed, M. S.; Prell, C.; Stagl, S.; Stringer, L. C.; Turner, A.; Worrall, F.

    2007-05-01

    Moorlands are unique environments found in uplands of the temperate zone including in the UK, New Zealand and Ireland, and in some high altitude tropical zones such as the Andean páramos. Many have been managed through grazing, burning or drainage practices. However, there are a number of other environmental and social factors that are likely to drive changes in management practice over the next few decades. Some moorlands have been severely degraded and in some countries conservation and restoration schemes are being attempted, particularly to revegetate bare soils. Native or non-native woodland planting may increase in some moorland environments while atmospheric deposition of many pollutants may also vary. Moorland environments are very sensitive to changes in management, climate or pollution. This paper reviews how environmental management change, such as changes in grazing or burning practices, may impact upon moorland processes based on existing scientific understanding. It also reviews the impacts of changes in climate and atmospheric deposition chemistry. The paper focuses on the UK moorlands as a case study of moorland landscapes that are in different states of degradation. Future research that is required to improve our understanding of moorland processes is outlined. The paper shows that there is a need for more holistic and spatial approaches to understanding moorland processes and management. There is also a need to develop approaches that combine understanding of interlinked social and natural processes.

  12. A pollen-based environmental reconstruction in Lake Hazar (Eastern Turkey) during the Late Pleistocene-Holocene: Example for the Eastern Mediterranean Realm

    NASA Astrophysics Data System (ADS)

    Biltekin, Demet; Kadir Eris, Kürsad; Namik Cagatay, Memet; Nagihan Arslan, Tugce; Akcer On, Sena; Acar, Dursun

    2016-04-01

    Eastern Mediterranean realm historically is a melting area for ancient civilisations. This region has been therefore anthropogenically influenced since the Late Pleistocene. The understanding the processes between vegetation and climate, pollen analysis is a significant proxy in the investigation of past climate, vegetation records and the human influence on the environment. In this research, we carried out the environmental changes during the Late Pleistocene-Holocene using multi-proxy analysis (palynology, XRF core scanner, magnetic susceptibility and TOC) in the sediment core obtained from 54.39 m depth on the northern shelf of Lake Hazar using a percussion piston corer. Lake Hazar (38° 31' N-39° 25' E) is located at ca. 1255 m above sea level, 22 km south-east of Elazıǧ city in eastern Turkey in the south-east Taurus Mountains. It is an oligotrophic, alkaline soda and a tectonic lake being situated on East Anatolian Fault Zone (EAFZ). The chronology of the sediment core has been determined using AMS radiocarbon method. We present the first pollen record from the core sediments in Lake Hazar, providing insight into multi-millennial scale climatic changes over the last ~15 14C ka BP. In the piston core, the Bølling/Allerød period is associated by the presence of Pistacia reflecting milder winter conditions with high biological productivity. Onset of the Younger Dryas (YD) period is marked by increase in herbaceous plants and lake level lowering that can also be documented by high magnetic susceptibility and Ca/Ti ratio. The spread of deciduous Quercus at the beginning of Holocene can be attributed to significant forestation due to a high humidity that was presumably sufficient for the establishment of oak forest. An increase in Quercus continued in most of the early and middle Holocene. The 3rd millenium crisis is strongly characterized by an increase in herbal elements, and a decline in Quercus, pointing to dry climatic conditions. The most striking

  13. Accelerating anthropogenic land surface change and the status of Pleistocene drumlins in New England.

    PubMed

    Woodcock, Deborah W; Rogan, John S; Blanchard, Samuel D

    2012-01-01

    Drumlins are glacially derived landforms that are prominent in the landscape over much of southern New England. We carried out a comprehensive ground-based survey in a three-town study area in eastern Massachusetts with the goals of establishing the extent to drumlins have been altered and assessing the associated environmental consequences and probable driving factors. Results show that many drumlins have been significantly altered through levelling and truncation (creation of steep cut and fill slopes), with projects involving movement of 1-1.5×10(6) m(3) of earth materials not now uncommon. Stormwater and wetlands infractions were documented at all the larger excavation sites and resulted in enforcement actions and fines in many cases; the broader environmental consequences of the loss/alteration of these forested uplands are harder to establish. The excavations are significant in terms of materials cycling: the movement of earth materials, when considered regionally, greatly exceeds natural denudation processes and is also greater than during other periods of high anthropogenic denudation. Our findings suggest that the region's glacial landscapes are at risk given current development patterns. The accelerating rate of land-surface change is undoubtedly also generalizable to other fast-developing regions of the United States. The landform alterations documented are part of a changing pattern of land use and vegetation cover since the Colonial era and are linked to shortages of land for development, current development and building practices, and lack of explicit rationales for preservation of the region's geoheritage.

  14. Paleoenvironments and climatic changes in the Italian Peninsula during the Early Pleistocene: evidence from dental wear patterns of the ungulate community of Coste San Giacomo

    NASA Astrophysics Data System (ADS)

    Strani, Flavia; DeMiguel, Daniel; Sardella, Raffaele; Bellucci, Luca

    2015-08-01

    Quaternary glacial/interglacial alternations, influenced by orbital obliquity cycles with a 41-ka long periodicity, started in the northern hemisphere around 2.6 Ma ago. Such alternations affected the terrestrial ecosystems, especially those of the Mediterranean region, with changes in the floristic communities and the dispersal and radiation of a number of large mammal open dwellers. Analyses of tooth wear patterns of ungulates from the Early Pleistocene site of Coste San Giacomo allow for a more objective reconstruction on the paleoenvironments and the climate in the Italian Peninsula during this epoch. Our results show that this area was composed by a mosaic of biomes, in particular by steppe and woodlands/wetlands. Evidence of such heterogeneity is provided by the wide spectrum of feeding behaviours found among the numerous ungulate herbivores here recorded, with cervids (Axis cf. lyra, Croizetoceros cf. ramosus and Eucladoceros sp.) exhibiting browser diets, most of the bovids (Gazella borbonica and Leptobos sp. and Gallogoral meneghinii) being intermediate feeders and the equid Equus stenonis showing a strict grazer behaviour. These results provide new insights for a timing of changing ecosystems in Southern Europe and reveal the environmental legacy of this global climatic shift, which is essential for understanding the early occupation of Homo in Europe. Thus, our data provide new evidence that such an environmental heterogeneity and a wide spectrum of available food resources could have been the main factors favouring the settlement of early species of Homo in this area.

  15. Seismic stratigraphy as indicator of late Pleistocene and Holocene sea level changes on the NE Brazilian continental shelf

    NASA Astrophysics Data System (ADS)

    Aquino da Silva, André G.; Stattegger, Karl; Schwarzer, Klaus; Vital, Helenice

    2016-10-01

    The late Pleistocene Holocene stratigraphic architecture on the northeastern Brazilian continental shelf off the Parnaíba Delta has been explored by high-resolution seismic profiles. The seismic surveys reveal the widespread distribution of incised valleys of different size in offshore continuation of the present-day Parnaiba delta. According to morphology two channel types can be distinguished: U-shaped channels in the eastern part and V-shaped channels in the western part. The stratigraphic successions were grouped into four seismic units separated by different seismic boundaries. The characteristics of the seismic boundaries and internal reflectors of the seismic units were used to distinguish between marine and riverine deposits. The incised-valleys architectural elements were used to link sedimentation processes and variations in base level from late Pleistocene channel avulsion and channel infill in the lowermost course of the paleo-Parnaíba River to marine sediments of the present-day inner shelf. The change of the depositional environments in relation to deglacial sea-level rise is compared to incised valley infills of the Mekong River and Red River systems in Southeast Asia.

  16. Deglaciation and latest Pleistocene and early Holocene glacier readvances on the Alaska Peninsula: Records of rapid climate change due to transient changes in solar intensity and atmospheric CO sub 2 content

    SciTech Connect

    Pinney, D.S.; Beget, J.E.

    1992-03-01

    Geologic mapping near Windy Creek, Katmai National Park, identified two sets of glacial deposits postdating late-Wisconsin Iliuk moraines and separated from them by volcaniclastic deposits laid down under ice-free conditions. Radiocarbon dating of organic material incorporated in the younger Katolinat till and in adjacent peat and lake sediments suggests that alpine glaciers on the northern Alaska Peninsula briefly expanded between ca. 8500 and 10,000 years B.P. Stratigraphic relationships and radiocarbon dates suggest an age for the older Ukak drift near the Pleistocene-Holocene boundary between ca. 10,000 and 12,000 years B.P. The authors suggest that rapid deglaciation following deposition of the Iliuk drift occurred ca. 13,000-12,000 years B.P. in response to large increases in global atmospheric greenhouse gas content, including C02. Short-term decreases in these concentrations, as recorded in polar ice cores, may be linked with brief periods of glacier expansion during the latest Pleistocene and early Holocene. A transient episode of low solar intensity may also have occurred during parts of the early Holocene. Rapid environmental changes and glacial fluctuations on the Alaska Peninsula may have been in response to transient changes in the concentration of atmospheric greenhouse gases and solar intensity.

  17. Pleistocene climate change promoted rapid diversification of aquatic invertebrates in Southeast Australia

    PubMed Central

    2012-01-01

    Background The Pleistocene Ice Ages were the most recent geohistorical event of major global impact, but their consequences for most parts of the Southern hemisphere remain poorly known. We investigate a radiation of ten species of Sternopriscus, the most species-rich genus of epigean Australian diving beetles. These species are distinct based on genital morphology but cannot be distinguished readily by mtDNA and nDNA because of genotype sharing caused by incomplete lineage sorting. Their genetic similarity suggests a Pleistocene origin. Results We use a dataset of 3858 bp of mitochondrial and nuclear DNA to reconstruct a phylogeny of Sternopriscus using gene and species trees. Diversification analyses support the finding of a recent rapid speciation event with estimated speciation rates of up to 2.40 species per MY, which is considerably higher than the proposed average rate of 0.16 species per MY for insects. Additionally, we use ecological niche modeling and analyze data on habitat preferences to test for niche divergence between species of the recent Sternopriscus radiation. These analyses show that the species can be characterized by a set of ecological variables referring to habitat, climate and altitude. Conclusions Our results suggest that the repeated isolation of populations in glacial refugia might have led to divergent ecological adaptations and the fixation of morphological traits supporting reproductive isolation and therefore may have promoted speciation. The recent Sternopriscus radiation fulfills many characteristics of a species flock and would be the first described example of an aquatic insect species flock. We argue that the species of this group may represent a stage in speciation past the species flock condition because of their mostly broad and often non-overlapping ranges and preferences for different habitat types. PMID:22873814

  18. Sequence stratigraphy and environmental background of the late Pleistocene and Holocene occupation in the Southeast Primor'ye (the Russian Far East)

    NASA Astrophysics Data System (ADS)

    Chlachula, Jiri; Krupyanko, Alexander A.

    2016-06-01

    The paper presents the results of Quaternary palaeoecology and geoarchaeology studies in the Zerkal'naya Basin, with new insights about sequenced natural shifts during the prehistoric occupation of this marginally explored NE Asian maritime territory. The Basin is part of the continental drainage system and the main physiographic and biotic corridor for peopling of the transitive coastal interior SE Primor'ye Region. The Final Pleistocene and Holocene environmental (biotic and abiotic) proxy records from the Upper/Final Palaeolithic to early historical sites document a dynamic climate change with vegetation cover transformations within riverine and mountain valley ecosystems of the Russian Far East. Most of the archaeological sites located on the low terraces and bedrock promontories along the main river channel and its tributary streams suggest traditional hunter gathered lifestyles based on seasonal salmon-fishing supplemented by pastoral economy. Tundra-forests with larch trees, dwarf birch thickets and polypod ferns from the basal stratigraphic units of the late Last Glacial occupation sites associated with the Upper Palaeolithic micro-blade and bifacial stone tool traditions (14C-dated to 19,000-12,000 cal yrs BP) indicate rather pronounced conditions and much lower MAT comparing today. Following a final Pleistocene cooling event, a major climate warming marked the onset of Holocene accompanied by a regional humidity increase promoting the formation of a mixed broadleaved-coniferous oak-dominant taiga, and culminating in the mid-Holocene Climatic Optimum. The appearance of mosaic parklands ca. 5,000-4,000 cal yrs BP. may be partly attributed to the expansion of the Far Eastern Neolithic cultures practicing forest clearance for pastures and dwellings. A progressing landscape opening indicated by the spread of light-demanding thickets and birch-dominated riverine biotopes with Artemisia suggests a further vegetation cover transformation during the late Neolithic

  19. Accelerating Anthropogenic Land Surface Change and the Status of Pleistocene Drumlins in New England

    PubMed Central

    Woodcock, Deborah W.; Rogan, John S.; Blanchard, Samuel D.

    2012-01-01

    Drumlins are glacially derived landforms that are prominent in the landscape over much of southern New England. We carried out a comprehensive ground-based survey in a three-town study area in eastern Massachusetts with the goals of establishing the extent to drumlins have been altered and assessing the associated environmental consequences and probable driving factors. Results show that many drumlins have been significantly altered through levelling and truncation (creation of steep cut and fill slopes), with projects involving movement of 1−1.5×106 m3 of earth materials not now uncommon. Stormwater and wetlands infractions were documented at all the larger excavation sites and resulted in enforcement actions and fines in many cases; the broader environmental consequences of the loss/alteration of these forested uplands are harder to establish. The excavations are significant in terms of materials cycling: the movement of earth materials, when considered regionally, greatly exceeds natural denudation processes and is also greater than during other periods of high anthropogenic denudation. Our findings suggest that the region’s glacial landscapes are at risk given current development patterns. The accelerating rate of land-surface change is undoubtedly also generalizable to other fast-developing regions of the United States. The landform alterations documented are part of a changing pattern of land use and vegetation cover since the Colonial era and are linked to shortages of land for development, current development and building practices, and lack of explicit rationales for preservation of the region’s geoheritage. PMID:23056410

  20. Calcareous Nannoplankton and Rapid Climate Change: Was High Climate Variability Responsible for Nannofloral Turnover during the PETM and Plio-Pleistocene?

    NASA Astrophysics Data System (ADS)

    Schueth, J.; Bralower, T. J.

    2010-12-01

    Modern climate change has the ability to drastically alter oceanic ecosystems and cause vast community disruptions and extinctions. However, the long-term effects of such drastic change are not known. Rapid climate change can push life to the limits of ecosystem tolerances, making extinction more likely. One of the best ways to understand long-term planktonic ecosystem responses is to study how previous climate changes impacted plankton assemblages. Calcareous nannoplankton are a good target for such an investigation because most species have very specific temperature and nutrient tolerances, and the group has a highly detailed fossil record. Most notably, there are two primary nannoplankton turnover events tied closely to significant climate changes, the rapid warming associated with the Paleocene-Eocene Thermal Maximum (PETM) and global cooling and enhanced glaciations in the northern hemisphere in the Pliocene and Pleistocene. We hypothesize that these nannoplankton turnovers were a result of rapid ecospace shifts caused by high rates of change in key environmental variables such as temperature and nutrients. Because rates are usually calculated as the change between data points, they may not represent true paleoecologic processes. To lessen this problem we have constructed rate models by applying paleoecological data from a few Ocean Drilling Program Sites to a Bayesian Linear Regression and Gaussian Process. This is a practice used in modern ecological studies, but has not been extensively applied to paleoecological problems. Our results show that nannoplankton abundance is most variable when the rate of change of environmental variables is the highest, and some taxa go extinct while environmental variability is high or slightly after a period of rapid climate change. Several taxa that are dominant or have a wide geographical range are less variable during rapid change, suggesting that these characteristics may lower the probability of extinction during rapid

  1. Late Pleistocene-Holocene paleoclimate in southwestern Brazilian Amazonia with basis on floristic changes interpreted from isotope data

    NASA Astrophysics Data System (ADS)

    Rossetti, D. F.; Cohen, M. C. L.; Pessenda, L. C. R.

    2015-12-01

    Previous late Quaternary paleoclimatic interpretations in Amazonia have considered fluctuating dry to wet episodes with changes from savanna to forest, a view that concurs with other proposals of undisturbed rainforest despite global oscillations. Most of this debate is based on pollen data, but such elements are scarce in Amazonian sedimentary records. This work interprets vegetation in the Late Pleistocene and Holocene in a southwestern Amazonia lowland using δ13C, δ15N, C/N integrated with geomorphology, sedimentology and radiocarbon dating. The goal was to reconstruct vegetation changes through time and analyze their relation to climate and sedimentary dynamics. Fluvial channel and floodplain deposits with phytoplankton, as well as C3 and C4 land plants, were recorded. Between 42,033-43,168 cal yr BP and 34,804-35,584 cal yr BP, C4 land plants increased as a result of a climate drier than todaýs. However, wet climate prevailed from this time-frame until the onset of the Last Glaciation Maximum. In the Pleistocene/Holocene transition, there was an increased contribution of C4 land plants potentially related to dry episodes. However, the increased contribution of this type of land plant is not synchronous with Holocene dry episodes previously documented for the Amazonian lowland. On the other hand, it is remarkable that the record of this plant type was verified only in sites with modern grassland confined to fluvial paleo-landforms. Thus, rather than due to a dry climatic episode, the recorded grassland expansion and its maintenance up to the present time in the studied sites is more likely associated with the evolution of depositional environments, being coincidental with the progressive abandonment of fluvial systems. An important conclusion derived from the present work is that great care must be placed when reconstructing late Quaternary paleoclimate in Amazonia based on changes in floristic patterns, as they may be also a response to sedimentary dynamics.

  2. Millennial- and centennial-scale vegetation and climate changes during the late Pleistocene and Holocene from northern New Mexico (USA)

    NASA Astrophysics Data System (ADS)

    Jiménez-Moreno, Gonzalo; Fawcett, Peter J.; Scott Anderson, R.

    2008-07-01

    High-resolution pollen and magnetic susceptibility (MS) data from a sediment core from an alpine bog (3100 m) in the Sangre de Cristo Mountains (New Mexico) record variations in treeline elevation and in sedimentation for the last 14 ka (cal yr BP). Strong correspondence between the paleovegetation and the MS profile suggests that both records can be used to reconstruct past climatic conditions. The coldest conditions in this area occurred at the end of the late Pleistocene during the Pinedale glaciation and the Younger Dryas chron. A general warming trend took place during the early Holocene, lasting until ˜5.6 ka, when the warmest conditions occurred. A progressive climate cooling is then observed until today. Millennial- and centennial-scale changes are also observed throughout the vegetation and MS records. The higher amplitude millennial-scale cold events appear to correlate with the timing and duration of episodes of enhanced sea-ice drift in the North Atlantic and the lower amplitude centennial-scale cold events may correlate with periods of lower solar activity. A solar-climate connection is suggested from these records by a prominent ca 200-yr cycle in tree pollen abundance, which may correlate with the 208 yr Suess solar cycle. This study shows an immediate response of the vegetation (treeline) to climate change at millennial- and centennial-scales, probably related to variations in summer insolation and solar activity during the late Pleistocene and Holocene. Such high-resolution studies are very important in order to predict future climate change and particularly in very arid areas, where human activity and economies are strongly influenced by climate.

  3. Paleogeographic and paleodrainage changes during Pleistocene glaciations (Po Plain, Northern Italy)

    NASA Astrophysics Data System (ADS)

    Garzanti, Eduardo; Vezzoli, Giovanni; Andò, Sergio

    2011-03-01

    The Po Basin, a Pliocene marine gulf between the Alps and the Apennines, was filled progressively from west to east and finally capped by fluvial sediments during the Pleistocene. By ~ 1.25 Ma, a meandering trunk river (paleoDora Baltea) reached westernmost Lombardia (Cilavegna); at ~ 1 Ma, the paleoAdda, entering the plain through the Como Valley, joined the paleoTicino in the Milano area. The coastline was directed NNE/SSW, and the open sea persisted east of ~ 10°E. Metamorphiclastic prodelta sediments of the Alpine trunk river reached central Lombardia (Pianengo) by MIS 36 and eastern Lombardia (Palosco) at MIS 31. Trunk-river delta foresets accumulated rapidly in easternmost Lombardia (Ghedi) during the Jaramillo. Fluvial sedimentation, continuous at Pianengo since MIS 28, eventually reached Ghedi at MIS 22. In this time interval, the embayment secluded between the prograding trunk-river delta and the Southalpine front was progressively filled by Southalpine fan deltas. With the onset of major Alpine glaciations in the late Matuyama, detrital supply increased markedly and fluvial deposits spread all over Lombardia. Because of outward growth of Alpine fans, the paleoDora Baltea was replaced at Cilavegna by the paleoSesia and paleoToce. Milano lay in the paleoAdda braidplain. Southalpine alluvial fans reached as far south as Pianengo. The paleoOglio glacier exited Lake Iseo at Cremignane. In the early Brunhes, accumulation rates markedly dropped in Lombardia; carbonaticlastic paleoPiave turbidites accumulated rapidly at Venezia, capped by the prograding paleoPo delta and finally by fluvial paleoBrenta-Bacchiglione deposits. Subsequently, accumulation rates decreased further, and paleosols developed during stages of prolonged exposure. The paleoTicino continued to flow southwest of Milano, where detritus from the paleoOlona is documented locally. PaleoAdda sediments were deposited at Milano and sedimentaclastic detritus at Trezzo up to a few meters from ground

  4. Genetic Consequences of Pleistocene Sea-Level Change on Hawaiian Megalagrion Damselflies.

    PubMed

    Jones, Brandon R; Jordan, Steve

    2015-01-01

    The Hawaiian Islands have long been an important laboratory for evolutionary research because their geological histories offer many natural experiments. For example, the Maui Nui complex, 4 islands that have been repeatedly connected and separated by fluctuating sea levels, lie near Hawaii Island, which has never been connected to another island. Here, we examine the genetic consequences of fluctuating island areas and connectivity using microsatellite analysis of 2 widespread, endemic Hawaiian damselflies. We screened 152 Megalagrion xanthomelas individuals from 5 islands at 14 loci and 34 Megalagrion pacificum from 3 islands at 11 loci to explore dispersal patterns and genetic diversity. Our data suggest that Pleistocene fluctuations in sea level alternated between creating land bridges that facilitated gene flow between once and future islands, and ocean channels that inhibited dispersal. Furthermore, interglacial periods of high sea stands likely reduced suitable habitat availability, causing the loss of genetic diversity on Maui Nui due to bottlenecks and founder events. Finally, we propose that gene flow from Molokai to Lanai may be enhanced by assisted dispersal from the trade winds that are channeled between volcanoes on western Maui and eastern Molokai. Our results emphasize the importance of variable microevolutionary processes in Hawaiian biogeography.

  5. Terminal Pleistocene change in mammal communities in southeastern Washington State, USA

    NASA Astrophysics Data System (ADS)

    Lyman, R. Lee

    2014-03-01

    Small mammal communities in western North America experienced declines in taxonomic richness across the late Pleistocene to Holocene transition (PHT), a recent natural global warming event. One community also experienced a decline in evenness and others replaced one species with a congener. Variability in response of small mammal communities to PHT warming is apparent. At the presently arid and xeric Marmes site in the Columbia Basin of southeastern Washington State, megafauna were absent by about 13,000 cal yr BP, evenness of small mammals declined about 11,700 cal yr BP and again about 11,400 cal yr BP whereas richness declined about 11,400 cal BP. Regional faunal turnover was, however, minimal among small-bodied taxa. Local mammal communities are depauperate as a result of megafaunal extinctions and subsequent decreases in small-mammal richness and evenness. The latter chronologically corresponds with a decrease in primary productivity driven by increasing warmth and aridity. More faunas must be studied in order to fully document the range of variability in the responses of mammalian communities to PHT warming. Documentation of patterns in those responses will facilitate understanding and enhance predictive accuracy with respect to responses of mammalian communities to modern global warming.

  6. The fluvial system response to abrupt climate change during the last cold stage: the Upper Pleistocene River Thames fluvial succession at Ashton Keynes, UK

    NASA Astrophysics Data System (ADS)

    Lewis, S. G.; Maddy, D.; Scaife, R. G.

    2001-02-01

    The last interglacial-glacial cycle (125-10 ka BP) is characterised by numerous rapid shifts in global climate on sub-Milankovitch timescales, recorded in the ocean and ice core records. These climatic fluctuations are clearly recorded in those European terrestrial sedimentary sequences that span this time period without interruption. In the UK, only fragmentary Upper Pleistocene sequences exist, mainly within the fluvial archive of the major river systems such as the Thames. The response of the upper River Thames to abrupt fluctuations in climate is documented in the fluvial sediments beneath the Floodplain Terrace (Northmoor Member of the Upper Thames Formation) at Ashton Keynes, Wiltshire. A number of criteria are set out by which significant changes in the fluvial system may be established from the sedimentological, palaeoecological and geochronological information contained within the succession. The sedimentary succession is divisible into four facies associations, on the basis of their sedimentology and bounding surface characteristics. These represent distinct phases of fluvial activity at the site and allow changes in fluvial style to be inferred. Palaeoecological reconstructions from pollen analysis of peats within the sequence provides an indication of the nature and direction of Late Glacial environmental change and optically stimulated luminescence and radiocarbon dating methods provide chronological control on the sequence. These data suggest that major changes in fluvial style are recorded within the succession, which can be related to the climatic fluctuations that took place on the oxygen isotope stage 5a/4 transition (approximately 70 ka BP) and the Devensian Late Glacial climatic warm-cold-warm oscillation (13-11 ka BP). The changes in fluvial style are a result of variations in sediment supply to the river resulting from changes in slope stability, vegetation cover and cold-climate mass movement processes and variations in discharge regime

  7. Caribbean Reef Response to Plio-Pleistocene Climate Change: Results of the Dominican Republic Drilling Project (DRDP)

    NASA Astrophysics Data System (ADS)

    Klaus, J.; McNeill, D. F.; Diaz, V.; Swart, P. K.; Pourmand, A.

    2014-12-01

    Caribbean reefs changed profoundly in taxonomic composition, diversity, and dominance structure during late Pliocene and Pleistocene climatic change. These changes coincide with protracted climatic deterioration and cooling between 2.0 to 0.8 Ma, and the onset of high amplitude sea-level fluctuations ~400 ka. The Dominican Republic Drilling Project (DRDP) was initiated to determine how climate change and global high-amplitude sea level changes influenced depositional patterns in Pliocene to Recent reef systems of the Caribbean. A transect of 7 core borings (~700 m total depth) were collected along the southern coast of the DR. New age constraints based on U/Th geochronometry and radiogenic Sr isotopes, combined with depositional lithofacies, faunal indicators, and stable isotope profiles have allowed us to correlate between wells and define the internal anatomy and stratal geometry of the individual reef sigmoids and sigmoid sets. Faunal records suggest most extinction occurred prior to ~1 Ma. Following this extinction, fringing reef margins of the Caribbean display a characteristic zonation in which Acropora palmata dominates shallow high-energy reef crests and Acropora cervicornis calmer fore-reef slopes and backreef lagoons. The dominance of acroporids across this zonation has been attributed to growth rates 5-100 times faster than other corals.

  8. Pliocene to Pleistocene climate and environmental history of Lake El'gygytgyn, Far East Russian Arctic, based on high-resolution inorganic geochemistry data

    NASA Astrophysics Data System (ADS)

    Wennrich, V.; Minyuk, P. S.; Borkhodoev, V.; Francke, A.; Ritter, B.; Nowaczyk, N. R.; Sauerbrey, M. A.; Brigham-Grette, J.; Melles, M.

    2014-07-01

    The 3.6 Ma sediment record of Lake El'gygytgyn/NE Russia, Far East Russian Arctic, represents the longest continuous climate archive of the terrestrial Arctic. Its elemental composition as determined by X-ray fluorescence scanning exhibits significant changes since the mid-Pliocene caused by climate-driven variations in primary production, postdepositional diagenetic processes, and lake circulation as well as weathering processes in its catchment. During the mid- to late Pliocene, warmer and wetter climatic conditions are reflected by elevated Si / Ti ratios, indicating enhanced diatom production in the lake. Prior to 3.3 Ma, this signal is overprinted by intensified detrital input from the catchment, visible in maxima of clastic-related proxies, such as K. In addition, calcite formation in the early lake history points to enhanced Ca flux into the lake caused by intensified weathering in the catchment. A lack of calcite deposition after ca. 3.3 Ma is linked to the development of permafrost in the region triggered by cooling in the mid-Pliocene. After ca. 3.0 Ma the elemental data suggest a gradual transition to Pleistocene-style glacial-interglacial cyclicity. In the early Pleistocene, the cyclicity was first dominated by variations on the 41 kyr obliquity band but experienced a change to a 100 kyr eccentricity dominance during the middle Pleistocene transition (MPT) at ca. 1.2-0.6 Ma. This clearly demonstrates the sensitivity of the Lake El'gygytgyn record to orbital forcing. A successive decrease of the baseline levels of the redox-sensitive Mn / Fe ratio and magnetic susceptibility between 2.3 and 1.8 Ma reflects an overall change in the bottom-water oxygenation due to an intensified occurrence of pervasive glacial episodes in the early Pleistocene. The coincidence with major changes in the North Pacific and Bering Sea paleoceanography at ca. 1.8 Ma implies that the change in lake hydrology was caused by a regional cooling in the North Pacific and the western

  9. Millennial-scale climate variability in response to changing glacial and orbital boundary conditions during the Mid-Pleistocene transition

    NASA Astrophysics Data System (ADS)

    Ferretti, Patrizia; Crowhurst, Simon; Drysdale, Russell; Bajo, Petra; Barbante, Carlo

    2016-04-01

    The Mid-Pleistocene transition represents perhaps the most important climate transition in the Quaternary period, yet it is one of the most poorly understood. Although the exact timing and mechanism of the onset of the "100 kyr" regime remain a matter of debate, it is well established that the overall periodicity of the glacial-interglacial cycles changed from a dominant 41 kyr obliquity periodicity prior to ~0.9 Ma to a dominant late Pleistocene 100 kyr variance. This change in the frequency domain was associated with an increase in the amplitude of global ice volume variations that, superimposed on a long-term climatic trend towards more glacial conditions over millions of years, produced some of the most extreme glaciations recorded. This interval of time has often been considered to be important in relation to long-term Milankovitch-scale climate variability. In contrast, here, special emphasis will be placed on assessing the presence and the characteristics of the suborbital-scale variability, and reconstructing the evolution of millennial-scale climate variability as the average climate state evolve toward generally colder conditions with larger ice sheets, and the spectral character of climate variability shifted from dominantly 41 kyr to 100 kyr. Appealing evidence suggests that millennial-scale climate variability is amplified during times of intense forcing changes, but this rapid variability has not been thoroughly explored yet at the time when the major changes in climate periodicity occurred. To address these questions, we have examined the record of climatic conditions from Marine Isotope Stages 25 to 16 (~970-650 ka) using high-resolution stable isotope records from benthic and planktonic foraminifera from a sedimentary sequence in the North Atlantic (Integrated Ocean Drilling Program Expedition 306, Site U1313) in order to assess millennial-scale changes in sea-surface and deep-water conditions, the dynamics of thermohaline deep-water circulation

  10. Medical responsibility and global environmental change.

    PubMed

    McCally, M; Cassel, C K

    1990-09-15

    Global environmental change threatens the habitability of the planet and the health of its inhabitants. Toxic pollution of air and water, acid rain, destruction of stratospheric ozone, waste, species extinction and, potentially, global warming are produced by the growing numbers and activities of human beings. Progression of these environmental changes could lead to unprecedented human suffering. Physicians can treat persons experiencing the consequences of environmental change but cannot individually prevent the cause of their suffering. Physicians have information and expertise about environmental change that can contribute to its slowing or prevention. Work to prevent global environmental change is consistent with the social responsibility of physicians and other health professionals.

  11. Late Pleistocene paleosols in the lower Mississippi River Valley: Documentation of regional base level change

    SciTech Connect

    Autin, W.J. ); Aslan, A. . Dept. of Geological Sciences)

    1992-01-01

    Late Pleistocene alluvial paleosols of the Mississippi River are developed in constructional fluvial deposits of ancestral meander belt, overbank, and flood basin deposits. At the type section of the Mt. Pleasant Bluff Alloformation of the Prairie Complex, the upper paleosol developed between 27 and 22 ka as part of a sequence of stacked paleosols that reflect cycles of an abandoned channel fill draped by proximal overbank deposits. Peoria Loess and mixed loess accumulated between 22 and 12 ka to bury the alluvial sequence. Base level lowering coincided with Late Wisconsinan glaciation and a minimum sea level at about 20 to 18 ka. Subsequent Holocene alluvial aggradation and valley wall plantation produced the present terrace escarpment. Soil morphology of the Mt. Pleasant Bluff Alloformation reflects two stages of soil development related to the removal of soils from an active flood plain environment to a terraced landscape position. Based on comparison with Holocene analogs, the first stage of pedogenesis in an active flood plain environment produced a hydromorphic soil as evidenced by color mottles, iron and carbonate nodules, and moderately developed B and C horizons. The second stage of development produced a more oxidized and leached soil profile as evidenced by an increase in soil color brightness, kaolinite content, and a decrease in smectite content and soil pH. In addition, pedogenic mixing by biogenic processes probably incorporated the A and E horizons into the overlying loess. A stratigraphic succession of alluvial paleosols may contain a record of regional base level rise and fall. However, an evaluation of eustatic, climatic, and/or tectonic influences on regional base level must first take into account local factors that control flood plain sedimentation and erosion.

  12. Microbial Community Dynamics from Permafrost Across the Pleistocene-Holocene Boundary and Response to Abrupt Climate Change

    NASA Astrophysics Data System (ADS)

    Hammad, A.; Mahony, M.; Froese, D. G.; Lanoil, B. D.

    2014-12-01

    Earth is currently undergoing rapid warming similar to that observed about 10,000 years ago at the end of the Pleistocene. We know a considerable amount about the adaptations and extinctions of mammals and plants at the Pleistocene/Holocene (P/H) boundary, but relatively little about changes at the microbial level. Due to permafrost soils' freezing anoxic conditions, they act as microbial diversity archives allowing us to determine how microbial communities adapted to the abrupt warming at the end of P. Since microbial community composition only helps differentiate viable and extant microorganisms in frozen permafrost, microbial activity in thawing permafrost must be investigated to provide a clear understanding of microbial response to climate change. Current increased temperatures will result in warming and potential thaw of permafrost and release of stored organic carbon, freeing it for microbial utilization; turning permafrost into a carbon source. Studying permafrost viable microbial communities' diversity and activity will provide a better understanding of how these microorganisms respond to soil edaphic variability due to climate change across the P/H boundary, providing insight into the changes that the soil community is currently undergoing in this modern era of rapid climate change. Modern soil, H and P permafrost cores were collected from Lucky Lady II site outside Dawson City, Yukon. 16S rRNA high throughput sequencing of permafrost DNA showed the same trends for total and viable community richness and diversity with both decreasing with permafrost depth and only the richness increasing in mid and early P. The modern, H and P soils had 50.9, 33.9, and 27.3% unique viable species and only 14% of the total number of viable species were shared by all soils. Gas flux measurements of thawed permafrost showed metabolic activity in modern and permafrost soils, aerobic CH­­4 consumption in modern, some H and P soils, and anaerobic CH­­4 production in one H

  13. Pleistocene climate change and the origin of two desert plant species, Pugionium cornutum and Pugionium dolabratum (Brassicaceae), in northwest China.

    PubMed

    Wang, Qian; Abbott, Richard J; Yu, Qiu-Shi; Lin, Kao; Liu, Jian-Quan

    2013-07-01

    Pleistocene climate change has had an important effect in shaping intraspecific genetic variation in many species; however, its role in driving speciation is less clear. We examined the possibility of a Pleistocene origin of the only two representatives of the genus Pugionium (Brassicaceae), Pugionium cornutum and Pugionium dolabratum, which occupy different desert habitats in northwest China. We surveyed sequence variation for internal transcribed spacer (ITS), three chloroplast (cp) DNA fragments, and eight low-copy nuclear genes among individuals sampled from 11 populations of each species across their geographic ranges. One ITS mutation distinguished the two species, whereas mutations in cpDNA and the eight low-copy nuclear gene sequences were not species-specific. Although interspecific divergence varied greatly among nuclear gene sequences, in each case divergence was estimated to have occurred within the Pleistocene when deserts expanded in northwest China. Our findings point to the importance of Pleistocene climate change, in this case an increase in aridity, as a cause of speciation in Pugionium as a result of divergence in different habitats that formed in association with the expansion of deserts in China.

  14. Geographic barriers and Pleistocene climate change shaped patterns of genetic variation in the Eastern Afromontane biodiversity hotspot

    PubMed Central

    Mairal, Mario; Sanmartín, Isabel; Herrero, Alberto; Pokorny, Lisa; Vargas, Pablo; Aldasoro, Juan J.; Alarcón, Marisa

    2017-01-01

    The Eastern African Afromontane forest is getting increased attention in conservation studies because of its high endemicity levels and shrinking geographic distribution. Phylogeographic studies have found evidence of high levels of genetic variation structured across the Great Rift System. Here, we use the epiphytic plant species Canarina eminii to explore causal explanations for this pattern. Phylogeographic analyses were undertaken using plastid regions and AFLP fragments. Population genetic analyses, Statistical Parsimony, and Bayesian methods were used to infer genetic diversity, genealogical relationships, structure, gene flow barriers, and the spatiotemporal evolution of populations. A strong phylogeographic structure was found, with two reciprocally monophyletic lineages on each side of the Great Rift System, high genetic exclusivity, and restricted gene flow among mountain ranges. We explain this pattern by topographic and ecological changes driven by geological rifting in Eastern Africa. Subsequent genetic structure is attributed to Pleistocene climatic changes, in which sky-islands acted as long-term refuges and cradles of genetic diversity. Our study highlights the importance of climate change and geographic barriers associated with the African Rift System in shaping population genetic patterns, as well as the need to preserve the high levels of exclusive and critically endangered biodiversity harboured by current patches of the Afromontane forest.

  15. The demographic response of a deciduous shrub (the Indigofera bungeana complex, Fabaceae) to the Pleistocene climate changes in East Asia.

    PubMed

    Zhao, Xue-Li; Gao, Xin-Fen; Zhu, Zhang-Ming; Gao, Yun-Dong; Xu, Bo

    2017-04-06

    East Asia harbors the highest level of floristic diversity among the world's temperate regions. Despite the increase in phylogeographic studies of temperate plants in East Asia, far less attention has been paid to widely distributed deciduous shrubs that widespread across several floral regions. We sequenced two chloroplast DNA (cpDNA) fragments (ndhJ-trnF and trnD-trnT) and one nuclear DNA (Pgk1) of 472 individuals from 51 populations of such a group, the Indigofera bungeana complex. We used population genetic data as well as ecological niche modelling to examine the evolutionary history and glacial refugia during the Last Glacial Maximum (LGM) of this group. We recovered 133 cpDNA and 68 nuclear haplotypes. The star-phylogeny of the recovered cpDNA and nuclear haplotypes and demographic analyses suggested distinct range expansion of I. bungeana complex have occurred during the early and middle Pleistocene. The climate change of the LGM might have affected little on the distribution of this complex based on the niche modelling. However, these climate changes and geographic isolation probably resulted in fixtures of the private haplotypes and genetic differentiations between regions. Our results suggested that this arid-tolerant species complex may have different responses to the Quaternary climate changes with those climate-sensitive species.

  16. Pleistocene climate, phylogeny, and climate envelope models: an integrative approach to better understand species' response to climate change.

    PubMed

    Lawing, A Michelle; Polly, P David

    2011-01-01

    Mean annual temperature reported by the Intergovernmental Panel on Climate Change increases at least 1.1°C to 6.4°C over the next 90 years. In context, a change in climate of 6°C is approximately the difference between the mean annual temperature of the Last Glacial Maximum (LGM) and our current warm interglacial. Species have been responding to changing climate throughout Earth's history and their previous biological responses can inform our expectations for future climate change. Here we synthesize geological evidence in the form of stable oxygen isotopes, general circulation paleoclimate models, species' evolutionary relatedness, and species' geographic distributions. We use the stable oxygen isotope record to develop a series of temporally high-resolution paleoclimate reconstructions spanning the Middle Pleistocene to Recent, which we use to map ancestral climatic envelope reconstructions for North American rattlesnakes. A simple linear interpolation between current climate and a general circulation paleoclimate model of the LGM using stable oxygen isotope ratios provides good estimates of paleoclimate at other time periods. We use geologically informed rates of change derived from these reconstructions to predict magnitudes and rates of change in species' suitable habitat over the next century. Our approach to modeling the past suitable habitat of species is general and can be adopted by others. We use multiple lines of evidence of past climate (isotopes and climate models), phylogenetic topology (to correct the models for long-term changes in the suitable habitat of a species), and the fossil record, however sparse, to cross check the models. Our models indicate the annual rate of displacement in a clade of rattlesnakes over the next century will be 2 to 3 orders of magnitude greater (430-2,420 m/yr) than it has been on average for the past 320 ky (2.3 m/yr).

  17. Pleistocene Climate, Phylogeny, and Climate Envelope Models: An Integrative Approach to Better Understand Species' Response to Climate Change

    PubMed Central

    Lawing, A. Michelle; Polly, P. David

    2011-01-01

    Mean annual temperature reported by the Intergovernmental Panel on Climate Change increases at least 1.1°C to 6.4°C over the next 90 years. In context, a change in climate of 6°C is approximately the difference between the mean annual temperature of the Last Glacial Maximum (LGM) and our current warm interglacial. Species have been responding to changing climate throughout Earth's history and their previous biological responses can inform our expectations for future climate change. Here we synthesize geological evidence in the form of stable oxygen isotopes, general circulation paleoclimate models, species' evolutionary relatedness, and species' geographic distributions. We use the stable oxygen isotope record to develop a series of temporally high-resolution paleoclimate reconstructions spanning the Middle Pleistocene to Recent, which we use to map ancestral climatic envelope reconstructions for North American rattlesnakes. A simple linear interpolation between current climate and a general circulation paleoclimate model of the LGM using stable oxygen isotope ratios provides good estimates of paleoclimate at other time periods. We use geologically informed rates of change derived from these reconstructions to predict magnitudes and rates of change in species' suitable habitat over the next century. Our approach to modeling the past suitable habitat of species is general and can be adopted by others. We use multiple lines of evidence of past climate (isotopes and climate models), phylogenetic topology (to correct the models for long-term changes in the suitable habitat of a species), and the fossil record, however sparse, to cross check the models. Our models indicate the annual rate of displacement in a clade of rattlesnakes over the next century will be 2 to 3 orders of magnitude greater (430-2,420 m/yr) than it has been on average for the past 320 ky (2.3 m/yr). PMID:22164305

  18. Calibrating a new proxy for Pleistocene climate change in southern Africa: the Mutual Ostracod Temperature Range method

    NASA Astrophysics Data System (ADS)

    Horne, David; Martens, Koen

    2010-05-01

    The Mutual Ostracod Temperature Range (MOTR) method has so far been applied only in the European Pleistocene, where it is proving effective in producing past air temperature range estimates that compare well with those obtained by other proxy methods (Horne, 2007; Horne & Mezquita, 2008; Holmes et al., in press). As an essential preliminary step towards applying the method in southern Africa, we have calibrated a training set of living ostracod species' distributions against a modern climate dataset and other available environmental data. The modern ostracod dataset is based on material held by the Royal Belgian Institute of Natural Sciences in Brussels, which constitutes the most diverse and comprehensive collection of southern African nonmarine ostracods available anywhere in the world. To date, c. 150 nominal species have been described from southern Africa (Martens, 2001) out of c. 450 species in the total Afrotropical area (Martens et al., 2008). We used an edited dataset comprising a total of 2,118 records of ostracod species from 748 localities in southern Africa, ranging in latitude from approximately 17 degrees S to 35 degrees S. We have explored the potential value and limitations of this training set for the estimation of past climatic parameters including mean July, January and annual air temperatures, precipitation, water conductivity and pH. Holmes, J. A., Atkinson, T., Darbyshire, D. P. F., Horne, D. J., Joordens, J., Roberts, M. B., Sinka, K. J. & Whittaker, J. E. (accepted, in press). Middle Pleistocene climate and hydrological environment at the Boxgrove hominin site (West Sussex, UK) from ostracod records. Quaternary Science Reviews, doi:10.1016/j.quascirev.2009.02.024, 1-13. Horne, D. J. 2007. A Mutual Temperature Range method for Quaternary palaeoclimatic analysis using European nonmarine Ostracoda. Quaternary Science Reviews, 26, 1398-1415. Horne, D. J. & Mezquita, F. 2008. Palaeoclimatic applications of large databases: developing and testing

  19. Nurse administrators: leading environmental change.

    PubMed

    Tullai-McGuinness, Susan; Ballard, Karen A; Gallagher, Rita Munley; Carpenter, Holly

    2010-01-01

    Evidence is building about the impact of environmental contaminants on patients and health care providers. The nurse administrator has a professional responsibility to provide leadership in assuring that the health care organization does not have a negative impact on health. This article presents critical environmental health concerns and an overview of the nursing profession efforts to improve the environment, which includes development of the American Nurses Association's Principles of Environmental Health for Nursing Practice with Implementation Strategies. An example is provided as to how the nurse administrator can use Appreciative Inquiry to harness the nurses collaborative energy for an environmentally healthy organization.

  20. Conference on Continental margin mass wasting and Pleistocene sea-level changes, August 13-15, 1980

    USGS Publications Warehouse

    Folger, David W.; Hathaway, J.C.

    1987-01-01

    A conference on Continental Margin Mass Wasting and Pleistocene Sea-Level Changes was held in Woods Hole, Mass., August 13-15, 1980. Forty-seven participants, representing many government, academic, and industrial organizations, discussed the current state of knowledge of the features of marine mass wasting and of the interrelations of factors influencing them. These factors include sediment source, composition, textures, sedimentation rates, climatic and sea-level changes, gas and gas hydrate (clathrate) contents of sediments, geotechnical characteristics, oceanographic and morphological factors, ground-water processes, and seismic events. The part played by these factors in the processes and features of mass movement and the engineering considerations imposed by the emplacement of manmade structures on the sea floor were considered vital to the evaluation of hazards involved in offshore exploration and development. The conference concluded with a call for bold programs to establish the probability of occurrence and the quantitative importance of these factors and to devise more reliable means of measurement, particularly in place, of the characteristics of the sediment and features involved.

  1. East Asian monsoon variation and climate changes in Jeju Island, Korea, during the latest Pleistocene to early Holocene

    NASA Astrophysics Data System (ADS)

    Lee, Seung Hyoun; Lee, Yong Il; Yoon, Ho Il; Yoo, Kyu-Cheul

    2008-09-01

    A 4.96-m-long sediment core from the Hanon paleo-maar in Jeju Island, Korea was studied to investigate the paleoclimatic change and East Asian monsoon variations during the latest Pleistocene to early Holocene (23,000-9000 cal yr BP). High-resolution TOC content, magnetic susceptibility, and major element composition data indicate that Jeju Island experienced the coldest climate around 18,000 cal yr BP, which corresponds to the last glacial maximum (LGM). Further, these multi-proxy data show an abrupt shift in climatic regime from cold and arid to warm and humid conditions at around 14,000 cal yr BP, which represents the commencement of the last major deglaciation. After the last major deglaciation, the TOC content decreased from 13,300 to 12,000 cal yr BP and from 11,500 to 9800 cal yr BP, thereby reflecting the weakening of the summer monsoon. The LGM in Jeju Island occurred later in comparison with the Chinese Loess Plateau. Such a disparity in climatic change events between central China and Jeju Island appears to be caused by the asynchrony between the coldest temperature event and the minimum precipitation event in central China and by the buffering effect of the Pacific Ocean.

  2. Late Pleistocene to Holocene paleoceanographic and paleo-climatic changes in Gulf of Gemlik, Sea of Marmara, Turkey

    NASA Astrophysics Data System (ADS)

    Filikci, Betül; Kadir Eriş, K.; Namık Çaǧatay, M.; Gasperini, Luca; Sabuncu, Asen; Acar, Dursun; Yalamaz, Burak

    2016-04-01

    Gulf of Gemlik is an east-west oriented marine inlet with a maximum depth of 113 m in the south-eastern part of the Sea of Marmara. It is located on the middle branch of the North Anatolian Fault Zone. While the Gulf of Gemlik is separated from the SoM by a bedrock sill at -50 m, there were presumably several disconnections during the Late Pleistocene to Holocene, but the timing of the youngest connection around the onset of the Holocene is still controversial. Here, we attempt to elucidate the paleoceanographic and paleoenvironmental changes during the late glacial-Holocene using the multi-proxy analysis of a core extending back to 13 ka BP. The multi-proxy data include physical and geochemical properties together with AMS 14C ages. The core sediments covering the time period of the last 13 ka BP consists of two main lithostratigraphic units. The lower Unit L2 represents the lacustrine phase of the gulf prior to 10.6 ka BP, while the upper Unit L1 is an overlying transgressive mud drape deposited during the main part of the Holocene. Unit L2 deposited prior 10.6 ka BP represents Bølling-Allerød and Younger Dryas climatic periods, when prograding shelf edge sediments were deposited in the form of well sorted medium sands with brackish water bivalve shells (Dreissenapolymorpha). At the beginning of the Holocene, the rising sea level in the Sea of Marmara breached the -50 m sill at 10.6 ka BP, and therefore the Gulf of Gemlik was converted into a marine realm. Soon after, the water stratifications allowed to the formation of the previously studied two sapropels in the gulf, as shown by increased TOC contents. μ-XRF Ca/Ti and Sr/Ca profiles of Unit L1 provide evidence of rapid climatic changes at 8.2 ka BP and 4.2 ka BP, representing cold and dry short climatic periods which are well correlated with previous marine and lake studies in İznik Lake south of the Sea of Marmara. Keywords: Gemlik Gulf, core, paleoclimate, Late Pleistocene to Holocene

  3. Latest Pleistocene-Holocene debris flow activity, Santa Catalina Mountains, Arizona; Implications for modern debris-flow hazards under a changing climate

    NASA Astrophysics Data System (ADS)

    Youberg, Ann M.; Webb, Robert H.; Fenton, Cassandra R.; Pearthree, Philip A.

    2014-08-01

    Hazard mitigation for extreme events such as debris flows requires geologic mapping and chronologic information, particularly for alluvial fans near mountain fronts in the southwestern United States. In July 2006, five consecutive days of monsoonal storms caused hundreds of debris flows in southeastern Arizona, particularly in the southern Santa Catalina Mountains north of Tucson. Before 2006, no historical debris flows from the Santa Catalina Mountains reached the populated mountain front, although abundant evidence of prehistoric debris flows is present on downslope alluvial fans. We used a combination of surficial geologic mapping and 10Be exposure dating to produce a debris-flow history for Pima and Finger Rock Canyons. The largest debris flows, of latest Pleistocene to early Holocene age, covered much of the apices of alluvial fans formed at the mouths of these canyons and extended up to 3 km downslope. These debris-flow deposits were inset against higher and older alluvial surfaces with few debris-flow deposits of late Pleistocene age. The 10Be ages in this study have considerable scatter for surfaces believed to be of uniform age, indicating the dual possibilities of inheritance from previous cosmic-ray exposure, as well as the potential for composite deposits derived from numerous debris flows. We then used an empirical inundation model, LAHARZ, to assess probable magnitudes of the older debris flows to evaluate possible initiation mechanisms. In-channel and terrace storage within the canyons is not sufficient to generate volumes likely needed to produce the larger late Pleistocene to early Holocene debris-flow deposits. The abundance of latest Pleistocene and early Holocene deposits suggests that large debris flows were generated during the instability associated with climate and vegetation changes at the Pleistocene-Holocene transition. Under present watershed conditions with limited sediment supplies, modern debris-flow hazards are generally limited to

  4. A ~600 kyr duration Early Pleistocene record from the West Turkana (Kenya) HSPDP drill site: elemental XRF variability to reconstruct climate change in Turkana Boy's backyard

    NASA Astrophysics Data System (ADS)

    Stockhecke, M.; Beck, C. C.; Brown, E. T.; Cohen, A.; Deino, A. L.; Feibel, C. S.; Sier, M.

    2015-12-01

    Outcrops in the Kenyan and Ethiopian rift valleys document repeated occurrences of freshwater lakes and wooded landscapes over the past 4 million years at locations that are currently seasonally-dry savanna. Studies of the rich fossil records, in combination with outcropping lacustrine sequences, led to major breakthroughs in our knowledge of driving factors in human evolution. However, study of continuous drill core from ancient lake basins provides a basis for to unravel East African climate dynamics in an unseen fashion. The Hominin Sites and Paleolakes Drilling Project (HSPDP), and the related Olorgesailie Drilling Project, recovered ~2 km of drill core since 2012. A major project goal is characterization of East African paleoclimate in order to evaluate its impact on hominin evolution. XRF core scanning data provide a means of evaluating records of past environmental conditions continuously and at high resolution. However, the HSPDP records contain complex lithologies reflecting repeated episodes of inundation and desiccation of the lake basins. Nevertheless, careful data evaluation based on detailed lithostratigraphy, which includes smear-slide microscopic analyses and X-radiographic images, allows disentanglement of complex signals and robust identification of continuous sequences for any cyclostratigraphic and statistical analysis. At the HSPDP Turkana Basin site a 175.6 m-long core the covers the Early Pleistocene time window during which hominids first expanded out of Africa and marine records document reorganization of tropical climate and the development of the strong Walker circulation. This drill site carries particular interest as it is located in only 2.5 km from the location of one of the most complete hominin skeletons ever recovered (Turkana Boy). Here we present a methodological approach to address the highly variable lithostratigraphy of the East African records to establish comprehensive and environmentally meaningful paleoclimate timeseries

  5. The recovery of ancient DNA from Dasypus bellus provides new possibilities for investigating late Pleistocene mammal response to climate change

    NASA Astrophysics Data System (ADS)

    Letts, Brandon; Shapiro, Beth

    2010-05-01

    Dasypus bellus, the 'beautiful armadillo,' is well known as a casualty of the Pleistocene megafaunal mass extinction event. Appearing in the fossil record about 2.5 Mya, D. bellus was widespread throughout the mid to southern United States and Mexico until it went extinct by about 10 kya. It was replaced by D. novemcinctus, the nine-banded armadillo, which is morphologically identical but smaller. The exact taxonomic status of D. bellus and its phylogenetic relationship with D. novemcinctus has been a subject of debate. In particular, it remains unresolved whether D. bellus was more closely related to North American than South American D. novemcinctus. To address this, we extracted and sequenced fragments of ancient mitochondrial DNA from surprisingly well-preserved remains of D. bellus recovered from Mefford Cave in Florida. Our results reveal a surprisingly close relationship between the extinct D. bellus and North American D. novemcinctus. Although southern climates have been considered inhospitable for the preservation of ancient DNA, thousands of bones per individual and the propensity of the armadillo to seek out shelter in caves makes preservation more likely than for other organisms. The armadillo may therefore make an excellent proxy organism for investigating the influence of climate change on animal populations south of the cold permafrost regions.

  6. Landscape response to late Pleistocene climate change in NW Argentina: Sediment flux modulated by basin geometry and connectivity

    NASA Astrophysics Data System (ADS)

    Schildgen, Taylor F.; Robinson, Ruth A. J.; Savi, Sara; Phillips, William M.; Spencer, Joel Q. G.; Bookhagen, Bodo; Scherler, Dirk; Tofelde, Stefanie; Alonso, Ricardo N.; Kubik, Peter W.; Binnie, Steven A.; Strecker, Manfred R.

    2016-02-01

    Fluvial fill terraces preserve sedimentary archives of landscape responses to climate change, typically over millennial timescales. In the Humahuaca Basin of NW Argentina (Eastern Cordillera, southern Central Andes), our 29 new optically stimulated luminescence ages of late Pleistocene fill terrace sediments demonstrate that the timing of past river aggradation occurred over different intervals on the western and eastern sides of the valley, despite their similar bedrock lithology, mean slopes, and precipitation. In the west, aggradation coincided with periods of increasing precipitation, while in the east, aggradation coincided with decreasing precipitation or more variable conditions. Erosion rates and grain size dependencies in our cosmogenic 10Be analyses of modern and fill terrace sediments reveal an increased importance of landsliding compared to today on the west side during aggradation, but of similar importance during aggradation on the east side. Differences in the timing of aggradation and the 10Be data likely result from differences in valley geometry, which causes sediment to be temporarily stored in perched basins on the east side. It appears as if periods of increasing precipitation triggered landslides throughout the region, which induced aggradation in the west, but blockage of the narrow bedrock gorges downstream from the perched basins in the east. As such, basin geometry and fluvial connectivity appear to strongly influence the timing of sediment movement through the system. For larger basins that integrate subbasins with differing geometries or degrees of connectivity (like Humahuaca), sedimentary responses to climate forcing are likely attenuated.

  7. Late Pleistocene variations in Antarctica sea ice. I - Effect of orbital isolation changes. II - Effect of interhemispheric deep-ocean heat exchange

    NASA Technical Reports Server (NTRS)

    Crowley, Thomas J.; Parkinson, Claire L.

    1988-01-01

    A dynamic-thermodynamic sea-ice model is presently used to ascertain the effects of orbitally-induced insolation changes on Antarctic sea-ice cover; the results thus obtained are compared with modified CLIMAP reconstructions of sea-ice 18,000 years ago. The minor influence exerted by insolation on Pleistocene sea-ice distributions is attributable to a number of factors. In the second part of this investigation, variations in the production of warm North Atlantic Deep Water are proposed as a mechanism constituting the linkage between climate fluctuations in the Northern and Southern hemispheres during the Pleistocene; this hypothesis is tested by examining the sensitivity of the dynamic-thermodynamic model for Antarctic sea-ice changes in vertical ocean heat flux, and comparing the simulations with modified CLIMAP sea-ice maps for 18,000 years ago.

  8. Environmental insurance adapts to changing needs

    SciTech Connect

    Vuono, M. )

    1995-03-01

    No longer simply a specialty service niche, environmental insurance has become an increasingly important asset to businesses worldwide. Companies of all sizes are using insurance as a proactive tool for prudent environmental risk management. During the last five years, the environmental insurance industry has matured to meet the ever-changing environmental insurance needs of business. A broad range of policies and programs offers coverage against damages caused by chemical spills, hazardous material and related environmental contaminants. Securing environmental insurance coverage has become as customary for many businesses as acquiring general liability and automobile insurance.

  9. The intensification of deep-water mass changes in the deep Atlantic Ocean throughout the Mid-Pleistocene climate transition

    NASA Astrophysics Data System (ADS)

    Poirier, R. K.; Billups, K.

    2012-12-01

    We examine the deep-water hydrography at Ocean Drilling Project (ODP) Site 1063 (subtropical North Atlantic, ~4600 meter water depth) using high-resolution benthic stable isotope (δ18O, δ13C) and grain size (% coarse, % Sortable Silt - SS, SS mean diameter) analyses from ~490 to 740 ka. The benthic foraminiferal δ13C record from Site 1063 provides a proxy for changes in the relative flux of lower North Atlantic Deep Water (NADW) through time. This record will refine the timing of increases in the formation of the densest components of NADW on the orbital and millennial-scale. We explore whether or not grain size analyses provide a proxy for changes in the relative velocity of the deep current. The new stable isotope data from Site 1063, when combined with the records of Poli et al. (2000), Ferretti et al. (2005), and Billups et al. (2011), tuned to the global benthic isotope stack (LR05) of Liesicki and Raymo (2004), provides a complete deep water record spanning Marine Isotope Stage (MIS) 25 to MIS 8 (~1020 to ~240 ka). Compiling published records from 16 additional sites, we use the Ocean Data View (ODV) program (Schlitzer, 2012) to map deep-water mass distributions through time. Results reveal an increasing distribution and influence of the NADW in relation to the Antarctic Bottom Water mass within interglacial periods beginning at MIS 15 continuing though the end of the Site 1063 record within MIS 9. Preliminary grain size analyses over a short interval of time reveal regular high frequency variations on the millennial scale. We anticipate having complete, high-resolution stable isotope and grain size records to discuss the hydrographic changes within the MIS 16/15 glacial/interglacial transition, as well as throughout the Mid-Pleistocene transition (MPT).

  10. ESR dating pleistocene barnacles from BC and Maine: a new method for tracking sea level change.

    PubMed

    Blackwell, Bonnie A B; Gong, J J J; Skinner, Anne R; Blais-Stevens, Andrée; Nelson, Robert E; Blickstein, Joel I B

    2010-02-01

    Barnacles have never been successfully dated by electron spin resonance (ESR). Living mainly in the intertidal zone, barnacles die when sea level changes cause their permanent exposure. Thus, dating the barnacles dates past sea level changes. From this, we can measure apparent sea level changes that occur due to ocean volume changes, crustal isostasy, and tectonics. ESR can date aragonitic mollusc shells ranging in age from 5 ka to at least 500 ka. By modifying the standard ESR method for molluscs to chemically dissolve 20 microm from off the shells, six barnacle samples from Norridgewock, Maine, and Khyex River, British Columbia, were tested for suitability for ESR dating. Due to Mn2+ interference peaks, the four Maine barnacle samples were not datable by ESR. Two barnacles from BC, which lacked Mn2+ interference, yielded a mean ESR age of 15.1 +/- 1.0 ka. These ages agree well with 14C dates on the barnacles themselves and wood in the overlying glaciomarine sediment. Although stability tests to calculate the mean dating signal lifetime and more ESR calibration tests against other barnacles of known age are needed to ensure the method's accuracy, ESR can indeed date Balanus, and thus, sea level changes.

  11. Red drifters and dark residents: the phylogeny and ecology of a Plio-Pleistocene dragonfly radiation reflects Africa's changing environment (Odonata, Libellulidae, Trithemis).

    PubMed

    Damm, Sandra; Dijkstra, Klaas-Douwe B; Hadrys, Heike

    2010-03-01

    In the last few million years, tropical Africa has experienced pronounced climatic shifts with progressive aridification. Such changes must have had a great impact on freshwater biota, such as Odonata. With about forty species, Trithemis dominates dragonfly communities across Africa, from rain-pools to streams, deserts to rainforests, and lowlands to highlands. Red-bodied species tend to favor exposed, standing and often temporary waters, have strong dispersal capacities, and some of the largest geographic ranges in the genus. Those in cooler habitats, like forest streams, are generally dark-bodied and more sedentary. We combined molecular analyses of ND1, 16S, and ITS (ITSI, 5.8S, and ITSII) with morphological, ecological, and geographical data for 81% of known Trithemis species, including three Asian and two Madagascan endemics. Using molecular clock analyses, the genus's origin was estimated 6-9Mya, with multiple lineages arising suddenly around 4Mya. Open stagnant habitats were inferred to be ancestral and the rise of Trithemis may have coincided with savannah-expansion in the late Miocene. The adaptation of red species to more ephemeral conditions leads to large ranges and limited radiation within those lineages. By contrast, three clades of dark species radiated in the Plio-Pleistocene, each within distinct ecological confines: (1) lowland streams, (2) highland streams, and (3) swampy habitats on alternating sides of the Congo-Zambezi watershed divide; together giving rise to the majority of species diversity in the genus. During Trithemis evolution, multiple shifts from open to more forested habitats and from standing to running waters occurred. Allopatry by habitat fragmentation may be the dominant force in speciation, but possibly genetic divergence across habitat gradients was also involved. The study demonstrates the importance of combining ecological and phylogenetic data to understand the origin of biological diversity under great environmental change.

  12. Ecological change on California's Channel Islands from the Pleistocene to the Anthropocene

    USGS Publications Warehouse

    Rick, Torben C.; Sillett, T. Scott; Ghalambor, Cameron K.; Hofman, Courtney A.; Ralls, Katherine; Anderson, R. Scott; Boser, Christina L.; Braje, Todd J.; Cayan, Daniel R.; Chesser, R. Terry; Collins, Paul W.; Erlandson, Jon M.; Faulkner, Kate R.; Fleischer, Robert; Funk, W. Chris; Galipeau, Russell; Huston, Ann; King, Julie; Laughrin, Lyndal L.; Maldonado, Jesus; McEachern, Kathryn; Muhs, Daniel R.; Newsome, Seth D.; Reeder-Myers, Leslie; Still, Christopher; Morrison, Scott A.

    2014-01-01

    Historical ecology is becoming an important focus in conservation biology and offers a promising tool to help guide ecosystem management. Here, we integrate data from multiple disciplines to illuminate the past, present, and future of biodiversity on California's Channel Islands, an archipelago that has undergone a wide range of land-use and ecological changes. Our analysis spans approximately 20,000 years, from before human occupation and through Native American hunter–gatherers, commercial ranchers and fishers, the US military, and other land managers. We demonstrate how long-term, interdisciplinary research provides insight into conservation decisions, such as setting ecosystem restoration goals, preserving rare and endemic taxa, and reducing the impacts of climate change on natural and cultural resources. We illustrate the importance of historical perspectives for understanding modern patterns and ecological change and present an approach that can be applied generally in conservation management planning.

  13. Biomarker based reconstruction of Pleistocene climate and environmental conditions in the Gulf of Alaska: Preliminary results obtained from IODP Expedition 341 sediments

    NASA Astrophysics Data System (ADS)

    Müller, Juliane; Sanchez Montes, Maria Luisa; McClymont, Erin; Stein, Ruediger; Fahl, Kirsten; Mangelsdorf, Kai; Wilkes, Heinz; 341 Scientists, Expedition

    2014-05-01

    A remarkable sedimentary record that extends from the Miocene to the late Pleistocene/Holocene has been drilled during IODP Expedition 341 (May - July 2013) in the Gulf of Alaska. The recovery and examination of sediments along a transect of five drill sites (U1417 - U1421) from the deep ocean towards the continental slope and shelf offshore the St. Elias Mountains enables the reconstruction of the palaeoceanographic and environmental development in the NE Pacific during a period of significant global cooling and directly addresses the overall research objectives of the IODP programme. The knowledge about palaeo sea surface conditions and their relation to climate changes in the subpolar NE Pacific is relatively scarce and mainly confined to the past 17 ka BP (Barron et al., 2009; Davies et al., 2011; Addison et al., 2012). Biomarker based reconstructions of the sea surface conditions (i.e. sea surface temperature (SST), sea ice coverage, marine primary productivity) that characterised the subpolar NE Pacific during critical time intervals of Plio- and Pleistocene climate change may provide new information on oceanic and atmospheric feedback mechanisms and further enable the identification of teleconnections between the palaeoceanographic evolution in the North Pacific and the North Atlantic. Here we present preliminary biomarker data obtained from sediments from the distal deepwater site U1417 and the proximal site U1419 located at the Gulf of Alaska continental slope. Variability in the distribution and abundance of short- and long-chain n-alkanes, sterols, and C25-highly branched isoprenoids (HBIs) is interpreted to reflect changes in the environmental setting. These data provide insight in marine primary productivity changes (in response to cooling and warming intervals) and the variable input of terrigenous organic matter via meltwater and/or iceberg discharge events. The C25-HBI diene/triene ratio - hitherto used as a sea ice proxy in the Southern Ocean

  14. Late Pleistocene Climatic Changes in the Western Mediterranean Inferred from Temperature, Productivity and Eolian Input Records: Implications for Human Dispersal

    NASA Astrophysics Data System (ADS)

    Hambach, B.; Rosell Mele, A.; Martinez-Garcia, A.

    2009-12-01

    The relation between climate and hominid dispersal has yet a number of unsettled issues, largely due to the lack of regional climate records in areas with significant hominid remains. Scientific evidence from the Mediterranean region indicates that humans evolved into their present form during key climatic intervals as indicated by the records of the earliest Europeans from Atapuerca (Spain) and Dmanisi (Georgia). However, it remains unclear which route was used by the early hominids to populate Europe (via the strait of Gibraltar or the Levantine Corridor). In this sense, it is still not clear if the climatic conditions during this period were favorable for hominid crossing via the strait of Gibraltar or not. To gain a better insight into the Iberian peninsular climate during the late Pleistocene, a marine sediment core from the Alboran Sea, Western Mediterranean, is used to reconstruct climate relevant variables related to surface ocean and atmospheric circulation by applying a set of organic geochemical proxies (biomarkers). In a first approach we present high resolution data (2 ky) for the interval from 0 to 500 ky. The results of this multi-biomarker analysis give new insights into past ocean climate conditions as well as into the processes that occurred onshore during this period. The reconstruction of sea surface temperatures is done by the analysis of alkenones (UK37-index). Total chlorins concentration is used as proxy for paleoproductivity. Terrestrial eolian inputs and vegetation changes are determined by the analysis of n-alkyl compounds (long chain n-alkanes, n-alkenols and n-alkanoic acids) which are major components of leaf waxes from terrestrial higher plants. Like mineral aerosols, these compounds are wind-transported from local vegetation sources to adjacent oceans where the particles settle and are preserved in ocean sediments with very little diagenetic alteration. These biomarkers offer a promising tool for reconstructing terrestrial vegetation

  15. Climate change, adaptive cycles, and the persistence of foraging economies during the late Pleistocene/Holocene transition in the Levant

    PubMed Central

    Rosen, Arlene M.; Rivera-Collazo, Isabel

    2012-01-01

    Climatic forcing during the Younger Dryas (∼12.9–11.5 ky B.P.) event has become the theoretical basis to explain the origins of agricultural lifestyles in the Levant by suggesting a failure of foraging societies to adjust. This explanation however, does not fit the scarcity of data for predomestication cultivation in the Natufian Period. The resilience of Younger Dryas foragers is better illustrated by a concept of adaptive cycles within a theory of adaptive change (resilience theory). Such cycles consist of four phases: release/collapse (Ω); reorganization (α), when the system restructures itself after a catastrophic stimulus through innovation and social memory—a period of greater resilience and less vulnerability; exploitation (r); and conservation (K), representing an increasingly rigid system that loses flexibility to change. The Kebarans and Late Natufians had similar responses to cold and dry conditions vs. Early Natufians and the Pre-Pottery Neolithic A responses to warm and wet climates. Kebarans and Late Natufians (α-phase) shifted to a broader-based diet and increased their mobility. Early Natufian and Pre-Pottery Neolithic A populations (r- and K-phases) had a growing investment in more narrowly focused, high-yield plant resources, but they maintained the broad range of hunted animals because of increased sedentism. These human adaptive cycles interlocked with plant and animal cycles. Forest and grassland vegetation responded to late Pleistocene and early Holocene climatic fluctuations, but prey animal cycles reflected the impact of human hunting pressure. The combination of these three adaptive cycles results in a model of human adaptation, showing potential for great sustainability of Levantine foraging systems even under adverse climatic conditions. PMID:22371591

  16. The impact of subsistence changes on humeral bilateral asymmetry in Terminal Pleistocene and Holocene Europe.

    PubMed

    Sládek, Vladimír; Ruff, Christopher B; Berner, Margit; Holt, Brigitte; Niskanen, Markku; Schuplerová, Eliška; Hora, Martin

    2016-03-01

    Analyses of upper limb bone bilateral asymmetry can shed light on manipulative behavior, sexual division of labor, and the effects of economic transitions on skeletal morphology. We compared the maximum (absolute) and directional asymmetry in humeral length, articular breadth, and cross-sectional diaphyseal geometry (CSG) in a large (n > 1200) European sample distributed among 11 archaeological periods from the Early Upper Paleolithic through the 20(th) century. Asymmetry in length and articular breadth is right-biased, but relatively small and fairly constant between temporal periods. Females show more asymmetry in length than males. This suggests a low impact of behavioral changes on asymmetry in length and breadth, but strong genetic control with probable sex linkage of asymmetry in length. Asymmetry in CSG properties is much more marked than in length and articular breadth, with sex-specific variation. In males, a major decline in asymmetry occurs between the Upper Paleolithic and Mesolithic. There is no further decline in asymmetry between the Mesolithic and Neolithic in males and only limited variation during the Holocene. In females, a major decline occurs between the Mesolithic and Neolithic, with resulting average directional asymmetry close to zero. Asymmetry among females continues to be very low in the subsequent Copper and Bronze Ages, but increases again in the Iron Age. Changes in female asymmetry result in an increase of sexual dimorphism during the early agricultural periods, followed by a decrease in the Iron Age. Sexual dimorphism again slightly declines after the Late Medieval. Our results indicate that changes in manipulative behavior were sex-specific with a probable higher impact of changes in hunting behavior on male asymmetry (e.g., shift from unimanual throwing to use of the bow-and-arrow) and food grain processing in females, specifically, use of two-handed saddle querns in the early agricultural periods and one-handed rotary querns in

  17. Temporal Change in Functional Richness and Evenness in the Eastern African Plio-Pleistocene Carnivoran Guild

    PubMed Central

    Werdelin, Lars; Lewis, Margaret E.

    2013-01-01

    We analyze functional richness and functional evenness of the carnivoran guild in eastern Africa from 3.5 Ma to 1.5 Ma, and compare them to the present day. The data consist of characters of the craniodental apparatus of 76 species of fossil and extant carnivorans, divided into four 0.5 Ma time slices from 3.5 to 1.5 Ma, together with the modern fauna. Focus is on large (>21.5 kg) carnivores. Results show that the large carnivore guild has lost nearly 99% of its functional richness since 3.5 Ma, in a process starting prior to 2 Ma. Measurement of functional evenness shows the modern large carnivore guild to be unique in being randomly distributed in morphospace while in all past time slices there is significant clustering of species. The results are analyzed in the light of known changes to climate and environment in eastern Africa. We conclude that climate change is unlikely to explain all of the changes found and suggest that the evolution of early hominins into carnivore niche space, especially the evolution of derived dietary strategies after 2 Ma, played a significant part in the reduction of carnivore functional richness. PMID:23483948

  18. Environmental, ecological, and paleoanthropological implications of the late Pleistocene mammalian fauna from Equus Cave, northern Cape Province, South Africa

    NASA Astrophysics Data System (ADS)

    Klein, Richard G.; Cruz-Uribe, Kathryn; Beaumont, Peter B.

    1991-07-01

    The late Pleistocene deposits of Equus Cave, northern Cape Province, South Africa, have provided more than 30,000 taxonomically identifiable mammal bones from 48 species. Context, associations, and features of the bone assemblage implicate brown hyenas as the main accumulators. The fauna is significant mainly because (1) it supplements previous evidence that regional climate was cooler and possibly also somewhat moister during part(s) of the late Pleistocene, but deviated less from the historic norm than in areas farther south; (2) it shows that Bond's springbok, which became extinct in the early Holocene, differed from the surviving common springbok not only in important morphological respects but also in reproductive pattern; and (3) it sustains earlier suggestions that an abundance of carnivores, a paucity of small hard bones, and increase in the cranial/postcranial ratio with species size, and exclusively attritional mortality profiles are features that tend to differentiate assemblages accumulated by brown hyenas from those accumulated by people. In addition, pending firmer dating, the fragmentary human fossils from Equus Cave may support an exclusively African origin for anatomically modern humans.

  19. Changes in northeast African hydrology and vegetation associated with Pliocene-Pleistocene sapropel cycles.

    PubMed

    Rose, Cassaundra; Polissar, Pratigya J; Tierney, Jessica E; Filley, Timothy; deMenocal, Peter B

    2016-07-05

    East African climate change since the Late Miocene consisted of persistent shorter-term, orbital-scale wet-dry cycles superimposed upon a long-term trend towards more open, grassy landscapes. Either or both of these modes of palaeoclimate variability may have influenced East African mammalian evolution, yet the interrelationship between these secular and orbital palaeoclimate signals remains poorly understood. Here, we explore whether the long-term secular climate change was also accompanied by significant changes at the orbital-scale. We develop northeast African hydroclimate and vegetation proxy data for two 100 kyr-duration windows near 3.05 and 1.75 Ma at ODP Site 967 in the eastern Mediterranean basin, where sedimentation is dominated by eastern Sahara dust input and Nile River run-off. These two windows were selected because they have comparable orbital configurations and bracket an important increase in East African C4 grasslands. We conducted high-resolution (2.5 kyr sampling) multiproxy biomarker, H- and C-isotopic analyses of plant waxes and lignin phenols to document orbital-scale changes in hydrology, vegetation and woody cover for these two intervals. Both intervals are dominated by large-amplitude, precession-scale (approx. 20 kyr) changes in northeast African vegetation and rainfall/run-off. The δ(13)Cwax values and lignin phenol composition record a variable but consistently C4 grass-dominated ecosystem for both intervals (50-80% C4). Precessional δDwax cycles were approximately 20-30‰ in peak-to-peak amplitude, comparable with other δDwax records of the Early Holocene African Humid Period. There were no significant differences in the means or variances of the δDwax or δ(13)Cwax data for the 3.05 and 1.75 Ma intervals studied, suggesting that the palaeohydrology and palaeovegetation responses to precessional forcing were similar for these two periods. Data for these two windows suggest that the eastern Sahara did not experience the

  20. Environmental Education: A Time of Change, a Time for Change

    ERIC Educational Resources Information Center

    Keene, Matt; Blumstein, Daniel T.

    2010-01-01

    We join the authors in this special issue in their call to embrace a culture of evaluation. Obstacles to change are formidable. Educators debate their purpose--provide knowledge or achieve environmental goals--and we have limited evidence of the effectiveness of environmental programs and policies. Change requires collaboration across…

  1. Phylogeographic Structure of a Tethyan Relict Capparis spinosa (Capparaceae) Traces Pleistocene Geologic and Climatic Changes in the Western Himalayas, Tianshan Mountains, and Adjacent Desert Regions

    PubMed Central

    Wang, Qian; Zhang, Ming-Li; Yin, Lin-Ke

    2016-01-01

    Complex geological movements more or less affected or changed floristic structures, while the alternation of glacials and interglacials is presumed to have further shaped the present discontinuous genetic pattern of temperate plants. Here we consider Capparis spinosa, a xeromorphic Tethyan relict, to discuss its divergence pattern and explore how it responded in a stepwise fashion to Pleistocene geologic and climatic changes. 267 individuals from 31 populations were sampled and 24 haplotypes were identified, based on three cpDNA fragments (trnL-trnF, rps12-rpl20, and ndhF). SAMOVA clustered the 31 populations into 5 major clades. AMOVA suggests that gene flow between them might be restricted by vicariance. Molecular clock dating indicates that intraspecific divergence began in early Pleistocene, consistent with a time of intense uplift of the Himalaya and Tianshan Mountains, and intensified in mid-Pleistocene. Species distribution modeling suggests range reduction in the high mountains during the Last Glacial Maximum (LGM) as a result of cold climates when glacier advanced, while gorges at midelevations in Tianshan appear to have served as refugia. Populations of low-altitude desert regions, on the other hand, probably experienced only marginal impacts from glaciation, according to the high levels of genetic diversity. PMID:27314028

  2. Phylogeographic Structure of a Tethyan Relict Capparis spinosa (Capparaceae) Traces Pleistocene Geologic and Climatic Changes in the Western Himalayas, Tianshan Mountains, and Adjacent Desert Regions.

    PubMed

    Wang, Qian; Zhang, Ming-Li; Yin, Lin-Ke

    2016-01-01

    Complex geological movements more or less affected or changed floristic structures, while the alternation of glacials and interglacials is presumed to have further shaped the present discontinuous genetic pattern of temperate plants. Here we consider Capparis spinosa, a xeromorphic Tethyan relict, to discuss its divergence pattern and explore how it responded in a stepwise fashion to Pleistocene geologic and climatic changes. 267 individuals from 31 populations were sampled and 24 haplotypes were identified, based on three cpDNA fragments (trnL-trnF, rps12-rpl20, and ndhF). SAMOVA clustered the 31 populations into 5 major clades. AMOVA suggests that gene flow between them might be restricted by vicariance. Molecular clock dating indicates that intraspecific divergence began in early Pleistocene, consistent with a time of intense uplift of the Himalaya and Tianshan Mountains, and intensified in mid-Pleistocene. Species distribution modeling suggests range reduction in the high mountains during the Last Glacial Maximum (LGM) as a result of cold climates when glacier advanced, while gorges at midelevations in Tianshan appear to have served as refugia. Populations of low-altitude desert regions, on the other hand, probably experienced only marginal impacts from glaciation, according to the high levels of genetic diversity.

  3. Grain size trends reveal alluvial fan sensitivity to late Pleistocene climate change

    NASA Astrophysics Data System (ADS)

    Whittaker, A. C.; D'Arcy, M. K.; Roda Boluda, D. C.

    2015-12-01

    The effects of climate change on eroding landscapes and the sedimentary record remain poorly understood. The measurement of grain size fining rates in stream-flow dominated deposits provides one way to address this issue because, in principle, these trends embed important information about the dynamics of sediment routing systems and their sensitivities to external forcing. At a fundamental level, downstream fining is often driven by selective deposition of sediment. The relative efficiency of this process is determined by the physical characteristics of the input sediment supply and the spatial distribution of subsidence rate, which generates the accommodation necessary for mass extraction. Here, we measure grain size fining rates from apex to toe on two alluvial fan systems in northern Death Valley, California, which have well-exposed modern and 70 ka surfaces, where the long-term tectonic boundary conditions are known and where climatic variation over this time period is well-constrained. We integrate a self-similar gravel fraction fining model, based on selective sediment extraction, with cosmogenically-derived catchment erosion rates and gravel fining data, to estimate the change in sediment flux that occurred between 70 ka and the present day. Our results show that a 30 % decrease in average precipitation rate led to a 20 % decrease in sediment flux and a clear increase in the down-fan rate of fining. This supports existing landscape evolution models that relate a decrease in precipitation rate to a decrease in sediment flux, but implies that this relationship may be sub-linear. This study offers a new approach to applying grain size fining models to mountain catchments and their alluvial fan systems, and shows fan stratigraphy can be highly sensitive to climate changes over <105 years. However we also observe that this sensitivity is lost when sediment is remobilised and recycled over a time period longer than the duration of the climatic perturbation.

  4. The Possible Role of Climatic Changes In Later Pleistocene Human Evolution and Extinctions

    NASA Astrophysics Data System (ADS)

    Stringer, C.

    Problems of chronological resolution greatly restrict our ability to match the Pleis- tocene fossil human succession to detailed palaeoclimatic records. This talk will ad- dress two relevant research areas. The first concerns the ancient human occupation of Britain, now the focus of a specific project (AHOB). Human occupation of Britain was influenced by two main factors, palaeogeography (particularly in relation to the periodic absence of a land bridge, largely controlled by climate) and palaeoclimate (particularly influenced by conditions in the North Atlantic). The second area con- cerns the European extinction of the Neanderthals and their replacement by modern humans. Particularly in the latter case, if we can move beyond reliance on uncalibrated radiocarbon chronologies, we may eventually be able to correlate human demographic changes, including Neanderthal extinction, with rapid climatic fluctuations.

  5. Orbital- and Millennial-Scale Changes in the Australasian Monsoon Through the Late Pleistocene

    NASA Astrophysics Data System (ADS)

    Gagan, M. K.; Ayliffe, L. K.; Scroxton, N. G.; Krause, C. E.; Kimbrough, A. K.; Hantoro, W. S.; Drysdale, R.; Hellstrom, J.; Cheng, H.; Edwards, R.; Zhao, J.; Griffiths, M. L.

    2012-12-01

    Speleothem 18O/16O records from China and Borneo have revealed changes in Asian monsoon rainfall over the last ~570,000 years (e.g. Wang et al. 2008, Cheng et al. 2010, Meckler et al. 2012), yet little is known about orbital- and millennial-scale climate change in the 'southern half' of the Australasian monsoon domain. To fill this gap, we aim to build speleothem 18O/16O records for the seasonal monsoon rainfall belt of south-central Indonesia. Between 2006 and 2011, we sampled speleothems in Flores and southwest Sulawesi (latitudes 5-9oS) with U-series ages extending to 92,000 yBP and ~470,000 yBP, respectively. Development of the 18O/16O records for Sulawesi is in progress, but the basal ages of the speleothems (onset of stalagmite growth) are intriguing because they cluster around glacial terminations, when the East Asian monsoon is known to have been weak (Cheng et al. 2010). There is clear antiphasing of the Flores and China speleothem 18O/16O records on precession time-scales over the last ~90,000 years. A distinct maximum in monsoon rainfall in Flores occurred ~21,000 yBP, suggesting the ITCZ moved south during the Last Glacial Maximum in response to the southern hemisphere summer insolation maximum. This finding indicates that ITCZ positioning in tropical Australasia, through its influence on large-scale oceanic-atmospheric circulation, could have played a key role in the rapid rise of atmospheric CO2 and global warming that ultimately led to the demise of the last ice age, as summarised by Denton et al. (2010) and others. The new Flores speleothem 18O/16O records also show that climate change in the North Atlantic region and Australasian monsoon rainfall are inextricably linked on millennial timescales (Griffiths et al. 2009, Lewis et al. 2011). For example, rapid warming in the North Atlantic region during Dansgaard-Oeschger Event 21 (~86,000 yBP) was linked to a synchronous northward shift of the Australasian ITCZ, marking the final demise of MIS 5b. In

  6. Modes of interglacial sea-level change: evidence from a late Pleistocene highstand in the UK

    NASA Astrophysics Data System (ADS)

    Saher, Margot; Barlow, Natasha; Long, Antony; Gehrels, Roland; Sparkes, Amy; Riley, Rachel; Penkman, Kirsty

    2014-05-01

    Interglacial sea-level extremes provide a useful analogue for future sea-level behaviour. The Holocene has been characterized by an overall stable sea level, but earlier interglacials, especially the Last Interglacial, are reported to have experienced meter-scale fluctuations (e.g. Rohling et al. 2008). Whether interglacial sea-level maxima are reached gradually or in 'steps' has serious societal implications, as the latter mechanism is associated with much higher rates of sea-level rise. Furthermore, the fluctuating Red Sea model of Last Interglacial sea-level change (Rohling et al. 2008) now underpins the high-end sea-level scenario ("High ++") adopted by the UK Climate Impact Programme. To better constrain interglacial sea-level behaviour, the iGlass consortium, funded by the UK Natural Environment Research Council, aims to constrain interglacial sea-level fluctuations from a variety of archives, e.g. corals, speleothems, marine isotopes and estuarine sediments. In this paper we investigate estuarine sediments and apply microfossil analyses, used widely to constrain Holocene sea-level changes, to sediments from interglacial deposits recovered from the Nar Valley, Norfolk, United Kingdom. A coring transect, comprised of 8 cores in 6 locations, traces an interglacial transgressive sequence inland. The litho- and biostratigraphy (mainly foraminifera) record the nature of this transgression. Sediments are either MIS 9 or 11 in age and include freshwater peats and marine clays, buried by glacial sands and gravels. Previous palynological work (Ventris, 1996) has indicates the sediments represent the entire interglacial period. The top of the marine clays has been tracked laterally for ~15 km and was found to have (at least) a 18 m vertical range, up to ~18 m above present mean sea level. Foraminiferal assemblages are dominated by the shallow water dweller Ammonia spp, and suggest only one sequence of deepening and shallowing. We further constrain the chronology using

  7. Late Pleistocene climate change and the global expansion of anatomically modern humans.

    PubMed

    Eriksson, Anders; Betti, Lia; Friend, Andrew D; Lycett, Stephen J; Singarayer, Joy S; von Cramon-Taubadel, Noreen; Valdes, Paul J; Balloux, Francois; Manica, Andrea

    2012-10-02

    The extent to which past climate change has dictated the pattern and timing of the out-of-Africa expansion by anatomically modern humans is currently unclear [Stewart JR, Stringer CB (2012) Science 335:1317-1321]. In particular, the incompleteness of the fossil record makes it difficult to quantify the effect of climate. Here, we take a different approach to this problem; rather than relying on the appearance of fossils or archaeological evidence to determine arrival times in different parts of the world, we use patterns of genetic variation in modern human populations to determine the plausibility of past demographic parameters. We develop a spatially explicit model of the expansion of anatomically modern humans and use climate reconstructions over the past 120 ky based on the Hadley Centre global climate model HadCM3 to quantify the possible effects of climate on human demography. The combinations of demographic parameters compatible with the current genetic makeup of worldwide populations indicate a clear effect of climate on past population densities. Our estimates of this effect, based on population genetics, capture the observed relationship between current climate and population density in modern hunter-gatherers worldwide, providing supporting evidence for the realism of our approach. Furthermore, although we did not use any archaeological and anthropological data to inform the model, the arrival times in different continents predicted by our model are also broadly consistent with the fossil and archaeological records. Our framework provides the most accurate spatiotemporal reconstruction of human demographic history available at present and will allow for a greater integration of genetic and archaeological evidence.

  8. Diagenesis and sea level change in a Pleistocene Coral Reef, San Salvador, Bahamas

    SciTech Connect

    White, B.; Kurkjy, K.A.; Curran, H.A.

    1985-02-01

    Near the Cockburn Town reef (dated 125,000 yr B.P.), precisely surveyed bench marks are related to accurately measured mean sea level, and they provide a convenient datum plane. This coral reef developed during a sea level highstand of no more than 10,000 yr, which was insufficient time for significant subsidence; however, subsidence of approximately 3 m may have occurred since the formation of the reef. Sea level changes were caused by fluctuations in glacial-ice volume. The upper beach to dune transition, which is in the calcarenites overlying the reef, is at +4 m. A minimum highstand of +7 m is indicated when corrected for subsidence. Below +2.5 m, marine aragonite cement occurs within the intragranular pore space of the following: Halimeda plates, benthic foraminifera, Favreina (Callianassid fecal pellets), gastropods, and corals. Marine aragonite cement also occurs as intergranular isopachous rims on matrix grains of coral rubblestone. Remaining pore space was partly to completely occluded by freshwater vadose calcite cements, which occur without marine cements in the overlying shallow subtidal, beach, and dune calcarenites. No unequivocal freshwater phreatic cements, which occur without marine cements in the overlying shallow subtidal, beach, and dune calcarenites. No unequivocal freshwater phreatic cements have been found, although syntaxial overgrowths and irregular calcite rims about grains do occur in finer grained sediments where local patches of freshwater saturation occurred within the vadose zone. Later calchification, which affected all facies, is characterized by alveolar texture, whisker calcite, microsparite, rare bladed calcite spar, Microcodium, and rhizocretions.

  9. Environmental education: a time of change, a time for change.

    PubMed

    Keene, Matt; Blumstein, Daniel T

    2010-05-01

    We join the authors in this special issue in their call to embrace a culture of evaluation. Obstacles to change are formidable. Educators debate their purpose--provide knowledge or achieve environmental goals--and we have limited evidence of the effectiveness of environmental programs and policies. Change requires collaboration across organizations and disciplines, targeted capacity building, and building systems of assessment into programs that enable more sophisticated evaluations. As in other fields, an evidence-based movement will increase the credibility and effectiveness of environmental education. A culture of evaluation offers educators a solid platform to collaboratively and efficiently achieve society's environmental goals.

  10. Mid-Pleistocene Orbital and Millennial Scale Climate Change in a 200 ky lacustrine sediment core from SW North America

    NASA Astrophysics Data System (ADS)

    Fawcett, P. J.; Werne, J. P.; Anderson, R. S.; Heikoop, J. M.; Brown, E. T.; Berke, M. A.; Smith, S.; Goff, F. E.; Hurley, L. L.; Cisneros Dozal, L. M.; Schouten, S.; Sinninghe Damsté, J. S.; Huang, Y.; Toney, J. L.; Fessenden, J. E.; Woldegabriel, G. W.; Geissman, J. W.; Allen, C. D.

    2009-12-01

    How anthropogenic climate change will affect hydroclimate of the arid regions of SW North America over the next century is a concern. Model projections suggest permanent “dust bowl-like” conditions; however, any anthropogenic change will be superimposed on long-term natural climate variability. We use the paleoclimatic record from an 82-m deep lacustrine sediment core (VC-3) from the Valles Caldera, New Mexico to examine continental climate variations spanning two glacial cycles through the middle Pleistocene from MIS 14 to MIS 10 (552 ka to ~360 ka). Both orbital and millennial-scale variations are evident in multiple proxies, and a strong relationship occurs between the warmest temperatures in the record and periods of extended aridity. We suggest that these periods of aridity are characterized by decreased winter as well as summer precipitation amounts. A new group of organic geochemical proxies (MBT and CBT) allow us to reconstruct the annual mean air temperature (MAT) of the Valles Caldera watershed as well as the watershed soil pH down the length of the core. We compare these proxies to climatically sensitive pollen taxa and other core properties. The MAT record of VC-3 shows considerable glacial-interglacial variation and significant variability within individual glacial and interglacial periods. The warmest interglacial MATs (5 to 7°C) compare favorably with modern MATs of ~5°C in the Valle Grande. MIS 11 has three warm substages, based on MAT estimates (2°C warmer than the cool substages), warm (Juniperus, Quercus, Rosaceae) vs. cool (Abies, Picea, Artemisia) pollen taxa and variation in aquatic productivity proxies (TOC, Si:Ti). The three warm substages of MIS 11 appear to correspond to the three precessional peaks that occur during this interval. Glacial MATs range from -5 to +2°C, with multiple millennial-scale temperature oscillations evident. Several of the interstadials show a distinct pattern of relatively slower temperature increases and

  11. Evolution of the western East African Rift System reflected in provenance changes of Miocene to Pleistocene synrift sediments (Albertine Rift, Uganda)

    NASA Astrophysics Data System (ADS)

    Schneider, Sandra; Hornung, Jens; Hinderer, Matthias

    2016-08-01

    Miocene to Pleistocene synrift sediments in the Albertine Graben reflect the complex geodynamic evolution in the Western branch of the East African Rift System. In this study we focus on the provenance of these siliciclastic deposits to identify sediment sources and supply paths with the ultimate goal to reconstruct the exhumation history of different tectonic blocks during prolonged rifting, with specific focus on the uplift of the Rwenzori Mountains in Uganda. We present framework and heavy mineral petrographic data combined with varietal studies of detrital garnet and rutile, based on logged sediment sections on the Ugandan side of Lake Albert (Kisegi-Nyabusosi area). The analyzed sedimentary units have a feldspatho-quartzose composition and distinct variations in heavy mineral assemblages and mineral chemical composition indicating two provenance changes. The Miocene part of the stratigraphy is dominated by garnet, zircon, tourmaline and rutile, whereas Pliocene to Pleistocene sediment yields high amounts of less stable amphibole and epidote. An abrupt switch in heavy mineral assemblages occurs during the early Pliocene ( 5.5-5.0 Ma) and clearly postdates the formation of Palaeolake Obweruka at 8 Ma. Provenance signatures point to major sediment supply from the northeast and subsequently from the southeast. We interpret this first shift as transition from the pre-rift to the syn-rift stage. In this scenario, formation of Palaeolake Obweruka is due to higher humidity in the upper Miocene, rather than forced rifting. A second change of sediment composition is documented by mineral geochemistry and coincides with fragmentation of Palaeolake Obweruka starting at 2.5 Ma. Detrital garnet in sediment of Miocene to Pliocene age is rich in pyrope and almandine and calculated Zr-in-rutile temperatures range between 550 and 950 °C. In contrast, garnet occurring in Pleistocene sediment (Nyabusosi Formation) has a higher spessartine component and rutile thermometry is

  12. Climate change in the four corners and adjacent regions: Implications for environmental restoration and land-use planning

    SciTech Connect

    Waugh, W.J.

    1995-09-01

    This document contains the workshop proceedings on Climate Change in the Four Corners and Adjacent Regions: Implications for Environmental Restoration and Land-Use Planning which took place September 12-14, 1994 in Grand Junction, Colorado. The workshop addressed three ways we can use paleoenvironmental data to gain a better understanding of climate change and its effects. (1) To serve as a retrospective baseline for interpreting past and projecting future climate-induced environmental change, (2) To differentiate the influences of climate and humans on past environmental change, and (3) To improve ecosystem management and restoration practices in the future. The papers presented at this workshop contained information on the following subjects: Paleoclimatic data from the Pleistocene and Holocene epochs, climate change and past cultures, and ecological resources and environmental restoration. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  13. Environmental changes in Lake Erie

    USGS Publications Warehouse

    Beeton, Alfred M.

    1961-01-01

    Comparison of data compiled during the past 60 years with those from recent studies shows that major changes have occurred in the bottom and fish faunas of Lake Erie. The bottom fauna was formerly dominated by the nymphs of Hexagenia, but at present midge larvae and oligochaetes are most abundant. Blue pike (Stizostedion vitreum glaucum) and cisco (Coregonus artedii), which formerly dominated the commercial catch, are scarce, while other species are more plentiful than formerly. The concentrations of various major ions have increased as much as 10 p.p.m. The mean annual water temperatures are approximately 2° F. warmer today than during the 1918-28 period. Low levels of dissolved oxygen have been observed several times since 1930, and recently very low concentrations were found in the bottom waters covering many square miles of the central basin. Although similar conditions may have existed in the past, it appears that greater areas are involved at the present.

  14. Environmental Change in Icy Moons

    NASA Astrophysics Data System (ADS)

    Pappalardo, R. T.; Vance, S.

    2014-12-01

    There is strong evidence that subsurface oceans could exist within several of the outer solar system's ice-rich moons, at Jupiter (Europa, Ganymede, and Callisto), Saturn (Enceladus and Titan), and Neptune (Triton). If liquid water is indeed available in these subsurface environments, then the availability of chemical energy becomes the greatest limitation on whether icy worlds could harbor life. Of these moons, the largest (Ganymede, Callisto, and Titan) are expected to harbor oceans deep within, and high-pressure H2O ice phases are expected farther beneath those deep oceans. In contrast, the oceans of smaller icy worlds—Europa, Enceladus, and Triton—are plausibly in direct contact with rock below. Given that serpentinization or other water-rock geochemical activity could supply reductants directly to their oceans, these icy worlds have the greatest chance to support present-day microbial life. Each of these three icy worlds displays spectacular resurfaced terrains that are very young (crater retention ages ~10s Myr and younger), with their internal activity linked to extremes in tidal heating today and/or in the geologically recent past. However, the degree of their tidal heating may have changed greatly over time. Europa is believed to experience cyclical tidal heating and activity; Enceladus may have experienced cyclical activity or a geologically recent pulse of activity; Triton may have experienced extreme tidal heating upon its capture and orbital circularization. Such dynamic pasts would pose challenges for any life within. We consider the possible effects of severe swings in the activity level of icy worlds, specifically the implications for delivery of chemical energy to their subsurface oceans.

  15. European wildcat populations are subdivided into five main biogeographic groups: consequences of Pleistocene climate changes or recent anthropogenic fragmentation?

    PubMed

    Mattucci, Federica; Oliveira, Rita; Lyons, Leslie A; Alves, Paulo C; Randi, Ettore

    2016-01-01

    Extant populations of the European wildcat are fragmented across the continent, the likely consequence of recent extirpations due to habitat loss and over-hunting. However, their underlying phylogeographic history has never been reconstructed. For testing the hypothesis that the European wildcat survived the Ice Age fragmented in Mediterranean refuges, we assayed the genetic variation at 31 microsatellites in 668 presumptive European wildcats sampled in 15 European countries. Moreover, to evaluate the extent of subspecies/population divergence and identify eventual wild × domestic cat hybrids, we genotyped 26 African wildcats from Sardinia and North Africa and 294 random-bred domestic cats. Results of multivariate analyses and Bayesian clustering confirmed that the European wild and the domestic cats (plus the African wildcats) belong to two well-differentiated clusters (average Ф ST = 0.159, r st = 0.392, P > 0.001; Analysis of molecular variance [AMOVA]). We identified from c. 5% to 10% cryptic hybrids in southern and central European populations. In contrast, wild-living cats in Hungary and Scotland showed deep signatures of genetic admixture and introgression with domestic cats. The European wildcats are subdivided into five main genetic clusters (average Ф ST = 0.103, r st = 0.143, P > 0.001; AMOVA) corresponding to five biogeographic groups, respectively, distributed in the Iberian Peninsula, central Europe, central Germany, Italian Peninsula and the island of Sicily, and in north-eastern Italy and northern Balkan regions (Dinaric Alps). Approximate Bayesian Computation simulations supported late Pleistocene-early Holocene population splittings (from c. 60 k to 10 k years ago), contemporary to the last Ice Age climatic changes. These results provide evidences for wildcat Mediterranean refuges in southwestern Europe, but the evolution history of eastern wildcat populations remains to be clarified. Historical genetic subdivisions suggest

  16. Middle Pleistocene climate and habitat change at Zhoukoudian, China, from the carbon and oxygen isotopic record from herbivore tooth enamel

    NASA Astrophysics Data System (ADS)

    Gaboardi, Mabry; Deng, Tao; Wang, Yang

    2005-05-01

    The Pleistocene deposits at Zhoukoudian, often referred to as the "Peking Man" site, contain dental remains from a diverse group of herbivores, including Equus sanmeniensis, Cervus elaphus, Cervus nippon, Megaloceros pachyosteus, Sus lydekkeri, and Dicerorhinus choukoutienensis. The carbon and oxygen isotopic compositions of structural carbonate within the enamel of these teeth are used to reconstruct the paleodiet and paleoenvironment of the mammals. The δ13C values of enamel from Zhoukoudian range from -2.3‰ to -13.0‰, indicating that these mammals consumed between ˜25% and 100% C 3 plants. The presence of significant amounts of C 4 plants in the diets of some herbivore species indicates that at the onset of the Middle Pleistocene local habitats included mixed C 3/C 4 vegetation. By approximately 470,000 yr ago, C 3 plants dominated the diets of herbivores studied, suggesting that the abundance of C 4 flora had decreased in the area. For all deer analyzed in this study, the values of δ13C and δ18O decrease substantially from about 720,000 to 470,000 yr ago. This trend may be due to a strengthening of the winter monsoon during the Middle Pleistocene.

  17. Effects of environmental change on wildlife health

    PubMed Central

    Acevedo-Whitehouse, Karina; Duffus, Amanda L. J.

    2009-01-01

    Environmental change has negatively affected most biological systems on our planet and is becoming of increasing concern for the well-being and survival of many species. At an organism level, effects encompass not only endocrine disruptions, sex-ratio changes and decreased reproductive parameters, but also include teratogenic and genotoxic effects, immunosuppression and other immune-system impairments that can lead directly to disease or increase the risk of acquiring disease. Living organisms will strive to maintain health by recognizing and resolving abnormal situations, such as the presence of invading microorganisms or harmful peptides, abnormal cell replication and deleterious mutations. However, fast-paced environmental changes may pose additional pressure on immunocompetence and health maintenance, which may seriously impact population viability and persistence. Here, we outline the importance of a functional immune system for survival and examine the effects that exposure to a rapidly changing environment might exert on immunocompetence. We then address the various levels at which anthropogenic environmental change might affect wildlife health and identify potential deficits in reproductive parameters that might arise owing to new immune challenges in the context of a rapidly changing environment. Throughout the paper, a series of examples and case studies are used to illustrate the impact of environmental change on wildlife health. PMID:19833653

  18. Global Environmental change: Understanding the Human Dimensions

    SciTech Connect

    Morrisette, P.M.

    1993-01-01

    This book is from the National Research Council's Committee on the Human dimensions of Global Change. The object is to examine what is known about human dimensions of global environmental change, identify the major immediate needs for knowledge, and recommend a strategy over the next 5-10 years. Case studies are used in human causes of global change. issues related to theory, methods, and data are covered, as well as institutional needs for interdicipinary approaches.

  19. Faunal turnover in Neogene to Recent Caribbean reef corals and region environmental change

    SciTech Connect

    Budd, A.F. . Geology Dept.); Johnson, K.G. . Palaeontology Dept.); Stemann, T.A. . Geologisches Inst.)

    1993-03-01

    Quantitative analyses of species richness and species extinction and origination rates in the Neogene to Recent Caribbean reef coral fauna show that a major episode of turnover occurred during middle to late Pliocene time (4--1 Ma). The data for the authors analyses consist of a new compilation of occurrences of 175 species and 49 genera in reef sequences in the Dominican Republic and Costa Rica and in 21 scattered sites ranging in age from 22 Ma to present. The results show that: (1) during turnover, more than 75% of all species living between 6--4 Ma (n = 82) became extinct; (2) during turnover, extinction and origination rates were equally and simultaneously high, and a relatively constant number of species was maintained in the fauna; (3) the taxonomic composition of Caribbean reefs remained relatively constant before (10--4 Ma) and after (1--0 Ma) turnover. Turnover therefore preceded the high frequency sea level oscillations of late Pleistocene time, and appears related to long-term, unidirectional changes in climate and/or ocean circulation across the Caribbean region in association with closure of the Isthmus of Panama. The observed correspondence between high origination and extinction rates indicates that the same environmental factors may have been associated with increases in both rates, and that local habitat differentiation and fragmentation may have been involved. Stability persisted in the region despite the severe environmental stresses associated with Pleistocene climate change.

  20. Adequation between environmental shifts and human speciations during the Plio-PleistoceneAdéquation entre changements environnementaux et spéciations humaines au Plio-Pléistocène

    NASA Astrophysics Data System (ADS)

    Zeitoun, Valery

    2000-01-01

    Several synthetic studies provide evidence of faunistic and floristic shifts as consequences of global climatic events around 2.5 and 1.8 Ma. Some authors are more confident in the role played by local tectonic events to explain such a change in terms of vicariance. It is possible that astronomic, tectonic and climatic variations are linked, as the lithosphere is a catalyst for biosphere more or less strong according to the period. The purpose of this paper is to confront independent environmental and anatomical data to try to understand the evolutionary process in hominids, with particular emphasis on species of the genus Homo in East Africa during the Plio-Pleistocene period. Thus the result of a cladistic analysis based on 35 Otus and 468 features of the calvaria is showing the onset of at least four species to describe the grade of Homo habilis, living in East Africa. The radiation is congruent with the contemporaneous environmental shifts around 2.5 Ma, as is also the case for bovids or cercopithecids. Some Homo erectus left Africa when another climatic pulse happened around 1.8 Ma.

  1. Transitional changes in microfossil assemblages in the Japan Sea from the Late Pliocene to Early Pleistocene related to global climatic and local tectonic events

    NASA Astrophysics Data System (ADS)

    Itaki, Takuya

    2016-12-01

    Many micropaleontological studies based on data from on-land sections, oil wells, and deep-sea drilling cores have provided important information about environmental changes in the Japan Sea that are related to the global climate and the local tectonics of the Japanese Islands. Here, major changes in the microfossil assemblages during the Late Pliocene to Early Pleistocene are reviewed. Late Pliocene (3.5-2.7 Ma) surface-water assemblages were characterized mainly by cold-temperate planktonic flora and fauna (nannofossils, diatoms, radiolarians, and planktonic foraminifera), suggesting that nutrient-rich North Pacific surface waters entered the Japan Sea via northern straits. The common occurrence of Pacific-type deep-water radiolarians during this period also suggests that deep water from the North Pacific entered the Japan Sea via the northern straits, indicating a sill depth >500 m. A weak warm-water influence is recognized along the Japanese coast, suggesting a small inflow of warm water via a southern strait. Nannofossil and sublittoral ostracod assemblages record an abrupt cooling event at 2.75 Ma that correlates with the onset of the Northern Hemisphere glaciation. Subsequently, cold intermediate- and deep-water assemblages of ostracods and radiolarians increased in abundance, suggesting active ventilation and the formation of the Japan Sea Proper Water, associated with a strengthened winter monsoon. Pacific-type deep-water radiolarians also disappeared around 2.75 Ma, which is attributed to the intermittent occurrence of deep anoxic environments and limited migration from the North Pacific, resulting from the near-closure or shallowing of the northern strait by a eustatic fall in sea level and tectonic uplift of northeastern Japan. A notable reduction in primary productivity from 2.3 to 1.3 Ma also suggests that the nutrient supply from the North Pacific was restricted by the near-closure of the northern strait. An increase in the abundance of subtropical

  2. Modeling crop responses to environmental change

    NASA Technical Reports Server (NTRS)

    Rosenzweig, Cynthia

    1993-01-01

    Potential biophysical responses of crops to climate change are studied focusing on the primary environmental variables which define the limits to agricultural crop growth and production, and the principal methods for predicting climate change impacts on crop geography and production. It is concluded that the principal uncertainties in the prediction of the impacts of climate change on agriculture reside in the contribution of the direct effects of increasing CO2, in potential changes inclimate variability, and the effects of adjustments mechanisms in the context of climatic changes.

  3. Holocene-Pleistocene Environmental Changes in Eastern Mediterranean Sediments: Foraminiferal and Geochemical Approach

    NASA Astrophysics Data System (ADS)

    Sinoussy Mohamed, K. S., Jr.; Ibrahim, M. I. A.; Moustafa, A. R.; Abd Elkarim, M. R.; Shreadah, M. M. A.

    2014-12-01

    The present study is based on gravity core sediment samples from the Eastern Mediterranean Sea located in 32° 20' 55" N and 31° 47' 79" E, in front of the Nile Delta Fan taken during METEOR cruise M70b (October 2006). The core is gravity one (St#822), 4.5 m long, and in 1089 m water depth. The study of benthic and planktic foraminifera is used to determine the microhabitat of the bottom sediments during warm and cold periods. Sapropels S1, S3 and S4 are encountered in the studied gravity core sample from the eastern Mediterranean. The sapropel layers S1, S3 and S4 were deposited during interglacial periods, characterized by a low foraminiferal numbers, reflecting eutrophic conditions. Glacial periods are characterized by high foraminiferal numbers due probably to an enhanced glacial productivity. Sapropel layers are distinguished by increase of Fe, TOC% (TOC%≥ 1.2%) and decrease of Ca concentrations as a result of the Blue Nile suspended particulate matter discharge during summer monsoon. Clay content increases at the sapropel depths that indicate an increase in the terrigenous input derived from the weathering of Ethiopian basalts. Temporal distribution of planktic and benthic foraminifera in the Nile deep sea fan sediments besides geochemical charcterization, palaeohydrological fluctuations, palaeoenvironment and microhabitat of foraminifera were reconstructed for the last 100000 years including glacial and interglacial periods. Formation of the Sapropel layers are synchronized with the decreasing of δ18O which means that the Mediterranean Sea received high amount of fresh water from the Nile river discharge. Clay content, TOC%, Ca-Fe cycles, oxygen and carbon isotopes and planktic foraminifera document the pluvial and arid periods throughout the 100000 years and define clearly the contributions of terrigenous and TOC% in the sapropel layers. Infauna/epifauna ratio and benthic foraminifera assemblages were used to reconstruct the microhabitat of the sea bottom during sapropel and cold periods.

  4. Paleoceanographic changes and population dynamics in two left-coiling events of Pulleniatina during early Pleistocene, ODP 1115B, western equatorial Pacific

    NASA Astrophysics Data System (ADS)

    Chiang, M.; Wei, K.; Chuang, C.; Lo, L.

    2013-12-01

    The alternately left-coiling (LC) and right-coiling (RC) dominance in the populations of planktonic foraminifera Pulleniatina genus defined a series L events during the past 4 Ma. These L events have been used as useful biostratigraphic markers for the Indo-Pacific region, especially the L5 event, which marks the top of Gelasian stage in Early Pleistocene. However, previous studies emphasized on the stratigraphic application of the L events and have little attention on the L events itself. This study focuses on the population dynamics of Pu. during L events and tries to examine the mechanism triggering the L events by studying Core ODP 1115 B (9°11' S, 151°34' E, water depth 1149 m) in Solomon Sea, western equatorial Pacific. Owing to the variance in morphology, we lumped all species of Pu. genus into a 'Pulleniatina complex' rather than subdividing them into different species. Specimens larger than 250 μm in each sample were sieved into six size-fractions. The Pu. complex as well as their coiling direction were identified under a stereomicroscope. To avoid biased sampling, we examined all Pu. complex specimens larger than 250 μm. LC and RC relative percentages as well as absolute abundances of Pu. complex in each size-fraction were counted, respectively. In setting LC relative percentage >50% as a threshold, we recognized a distinctive L6 event (~ 2.202 - 2.175 Ma, began between MIS 85 - 84 and ended between MIS 83 - 82), a prominent L5 event (~ 2.147 - 1.875 Ma, began between MIS 82 - 81 and ended between MIS 71 - 70), and could not find a clear L4 event as reported by Saito (1976). The onset of the L5 event was marked by a dramatic reduction of absolute abundance of RC forms that give observers an impression of LC forms dominance. During the L5 event, the LC relative percentages fluctuated by 20 to 40%. The ending of the L5event was characterized by a slow recovery of RC forms in absolute abundance. L6 event was the result of two sudden significant changes

  5. Environmental magnetism and excursion record of the Pleistocene-Holocene transition in marine cores, West Coast South Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Nelson, F. E.; Wilson, G. S.; Party, Shipboard

    2009-04-01

    Homologous ARM susceptibility (κARM) and magnetic susceptibility (κ) records from u-channel samples of five short cores (TAN0712 cores 14, 15, 17, 23, 27) record the Pleistocene - Holocene transition off the West Coast of the South Island, New Zealand. Cores were collected in water depths ranging from 880-2817 m. Cores 14, 15 and 17 are situated along the north levee of Moeraki Canyon. Cores 15 and 17 are kasten cores that record a relatively homogeneous concentration of single domain (SD) grains. Core 14 is a piston core slightly closer to the edge of Moeraki Canyon. From end of core (EOC) at 3.2 m to 0.75 m, the dominance of κ indicates coarse, multi-domain (MD) magnetic grains; however, low κ units (10-20 cms thick) occur at a mean interval of 0.71 m (n=3). Cores 23 and 27 are situated on the north-west margin of Milford Basin. Variations in magnetic mineral concentration in core 23 occur approximately every 26 cm. Fast Fourier Transform analysis confirms the 26 cm cycle, although it has relatively low spectral power. Core 27 also has a short interval of variable concentration. This variation in 'magnetisability' is inferred to result from fluctuating carbonate concentrations during the glacial period leading up to the Last Glacial Maximum (LGM). All three longer piston cores (27, 23, 14) contain a coarse MD interval ranging from 0.35-1 m in thickness, which we infer to represent influx of outwash at the termination of the LGM. Overlying this interval, all five cores display a consistent SD signal inferred to represent hemipelagic sedimentation during the Holocene. Possible geomagnetic excursions are recorded in four of the cores. An inclination transition to 34.2∘ combined with a 180∘ declination transition and NRM intensity low at 0.35-0.39 m in core 17 suggests a true geomagnetic excursion. Core 15 also has inclination shallowing and an intensity low at 0.45 m. An older excursion in core 27 at 2.54-2.69 m and in core 14 at ~2.8 m may correlate. The

  6. The Bonneville Estates Rockshelter rodent fauna and changes in Late Pleistocene-Middle Holocene climates and biogeography in the Northern Bonneville Basin, USA

    NASA Astrophysics Data System (ADS)

    Schmitt, Dave N.; Lupo, Karen D.

    2012-07-01

    Excavations at Bonneville Estates Rockshelter, Nevada recovered rodent remains from stratified deposits spanning the past ca. 12,500 14C yr BP (14,800 cal yr BP). Specimens from horizons dating to the late Pleistocene and early Holocene include species adapted to montane and moist and cool habitats, including yellow-bellied marmot (Marmota flaviventris) and bushy-tailed woodrat (Neotoma cinerea). Shortly after 9000 14C BP (10,200 cal yr BP) these mammals became locally extinct, or nearly so, taxonomic diversity declined, and the region became dominated by desert woodrats (Neotoma lepida) and other species well-adapted to xeric, low-elevation settings. The timing and nature of changes in the Bonneville Estates rodent fauna are similar to records reported from nearby Homestead and Camels Back caves and provide corroborative data on terminal Pleistocene-early Holocene environments and mammalian responses to middle Holocene desertification. Moreover, the presence of northern pocket gopher (Thomomys talpoides) at Bonneville Estates adds to a sparse regional record for that species and, similar to Homestead Cave, it appears that the ca. 9500 14C yr BP (10,800 cal yr BP) replacement of the northern pocket gopher by Botta's pocket gopher in the Great Salt Lake Desert vicinity was also in response to climate change.

  7. Evidence for survival of Pleistocene climatic changes in Northern refugia by the land snail Trochoidea geyeri (Soós 1926) (Helicellinae, Stylommatophora)

    PubMed Central

    Pfenninger, Markus; Posada, David; Magnin, Frédéric

    2003-01-01

    Background The study of organisms with restricted dispersal abilities and presence in the fossil record is particularly adequate to understand the impact of climate changes on the distribution and genetic structure of species. Trochoidea geyeri (Soós 1926) is a land snail restricted to a patchy, insular distribution in Germany and France. Fossil evidence suggests that current populations of T. geyeri are relicts of a much more widespread distribution during more favourable climatic periods in the Pleistocene. Results Phylogeographic analysis of the mitochondrial 16S rDNA and nuclear ITS-1 sequence variation was used to infer the history of the remnant populations of T. geyeri. Nested clade analysis for both loci suggested that the origin of the species is in the Provence from where it expanded its range first to Southwest France and subsequently from there to Germany. Estimated divergence times predating the last glacial maximum between 25–17 ka implied that the colonization of the northern part of the current species range occurred during the Pleistocene. Conclusion We conclude that T. geyeri could quite successfully persist in cryptic refugia during major climatic changes in the past, despite of a restricted capacity of individuals to actively avoid unfavourable conditions. PMID:12720575

  8. Comparative context of Plio-Pleistocene hominin brain evolution.

    PubMed

    Elton, S; Bishop, L C; Wood, B

    2001-07-01

    One of the distinguishing features of Homo sapiens is its absolutely and relatively large brain. This feature is also seen in less extreme form in some fossil Homo species. However, are increases in brain size during the Plio-Pleistocene only seen in Homo, and is brain enlargement among Plio-Pleistocene primates confined to hominins? This study examines evidence for changes in brain size for species and lineage samples of three synchronic East African fossil primate groups, the two hominin genera Homo and Paranthropus, and the cercopithecoid genus Theropithecus. Hominin endocranial capacity data were taken from the literature, but it was necessary to develop an indirect method for estimating the endocranial volume of Theropithecus. Bivariate and multivariate regression equations relating measured endocranial volume to three external cranial dimensions were developed from a large (ca. 340) sample of modern African cercopithecoids. These equations were used to estimate the endocranial volumes of 20 Theropithecus specimens from the African Plio-Pleistocene. Spearman's rho and the Hubert nonparametric test were used to search for evidence of temporal trends in both the hominin and Theropithecus data. Endocranial volume apparently increased over time in both Homo and Paranthropus boisei, but there was no evidence for temporal trends in the endocranial volume of Theropithecus. Thus, hypotheses which suggest a mix of environmental, social, dietary, or other factors as catalysts for increasing brain in Plio-Pleistocene primates must accommodate evidence of brain enlargement in both Homo and Paranthropus, and explain why this phenomenon appears to be restricted to hominins.

  9. Palynological evidence for late miocene, pliocene and early pleistocene climate changes in the middle U.S. Atlantic Coastal Plain

    USGS Publications Warehouse

    Groot, J.J.

    1991-01-01

    Palynomorph assemblages from eight geologic formations in the Middle Atlantic Coastal Plain, ranging in age from latest Miocene to Early Pleistocene, have been interpreted in terms of terrestrial paleoclimates. The data suggest that a warm-temperate to subtropical climate, warmer than at present, prevailed at the close of the Miocene and the beginning of the Pliocene. At that time, there was little or no temperature gradient within the study area (36??30??? to 39??N). This warm period was followed by a warm-temperate interval in Virginia and North Carolina, with temperatures probably not very different from those of today, although a slight warming trend probably occurred during the deposition of the Colerain Beach Member of the Chowan River Formation. A definite cool interval is indicated by the presence of spruce pollen in the Bacons Castle Formation of Virginia. This interval is interpreted to have begun about 2.3-2.4 Ma, or possibly slightly later, simultaneous with the cooling that has been recorded in deep-sea cores of the North Atlantic Ocean, and in the pre-Tiglian of western Europe. This was followed by a warmer-than-present period that may be correlated with the Tiglian of the latest Pliocene. Finally, palynological data from the Cape May Formation of New Jersey suggest that a warm-temperate (warmer than at present) climate prevailed during the Early Pleistocene. ?? 1991.

  10. Organic Geochemical Reconstructions from Lake El'gygytgyn, Northeast Arctic Siberia, Constrain Arctic Temperature and Hydrologic Change Across the Pliocene-Pleistocene Transition

    NASA Astrophysics Data System (ADS)

    Keisling, B. A.; Brigham-Grette, J.; Castañeda, I. S.

    2015-12-01

    The Pliocene epoch (5-2.65 Ma) represents an analog for future climate conditions, with pCO2 and continental configurations similar to present. Thus, understanding the climatic changes that occurred during the Pliocene might be useful for predicting how climate will involve in the future. In pursuit of this goal, reconstructions based on ocean sediments have proven useful, but also highlighted inconsistencies and gaps in our understanding of the climate mechanisms important during the Pliocene. For example, the conditions that drove ice growth and decay in the late Pliocene and early Pleistocene, especially during a period known as the intensification of northern hemisphere glaciation, are debated. A major obstacle to refining our knowledge of such phenomena is the lack of paleoclimate records from terrestrial sites. To address this shortcoming, we develop a record of climatic changes across the Pliocene-Pleistocene transition, spanning 2.82-2.41 million years ago (Ma), in a lacustrine record from Arctic Russia. Here we use branched glycerol dialkyl glycerol tetraethers (brGDGTs) and the hydrogen isotopic composition of leaf waxes (n-alkane δD) to reconstruct temperature and hydrology during this interval. We find close coupling between the proxies from 2.55 - 2.41 Ma, suggesting glacial-interglacial temperature changes of 5-10ºC during this time in the Arctic. Prior to this, the proxies do not agree on the character of climate changes, suggesting a decoupling of temperature and the hydrologic cycle in the Arctic from 2.7-2.55 Ma. Shifts in the leaf wax hydrogen isotope record at 2.69 and 2.73 Ma, independent of changes in temperature, point to potentially dramatic changes in the high-latitude hydrological cycle at these times. This record allows us, for the first time, to put discontinuous and time-uncertain records into regional perspective and better constrain the evolution of multiple independent Arctic feedback systems during the Pliocene and into the

  11. Environmental change makes robust ecological networks fragile

    PubMed Central

    Strona, Giovanni; Lafferty, Kevin D.

    2016-01-01

    Complex ecological networks appear robust to primary extinctions, possibly due to consumers' tendency to specialize on dependable (available and persistent) resources. However, modifications to the conditions under which the network has evolved might alter resource dependability. Here, we ask whether adaptation to historical conditions can increase community robustness, and whether such robustness can protect communities from collapse when conditions change. Using artificial life simulations, we first evolved digital consumer-resource networks that we subsequently subjected to rapid environmental change. We then investigated how empirical host–parasite networks would respond to historical, random and expected extinction sequences. In both the cases, networks were far more robust to historical conditions than new ones, suggesting that new environmental challenges, as expected under global change, might collapse otherwise robust natural ecosystems. PMID:27511722

  12. Environmental change makes robust ecological networks fragile

    USGS Publications Warehouse

    Strona, Giovanni; Lafferty, Kevin D.

    2016-01-01

    Complex ecological networks appear robust to primary extinctions, possibly due to consumers’ tendency to specialize on dependable (available and persistent) resources. However, modifications to the conditions under which the network has evolved might alter resource dependability. Here, we ask whether adaptation to historical conditions can increase community robustness, and whether such robustness can protect communities from collapse when conditions change. Using artificial life simulations, we first evolved digital consumer-resource networks that we subsequently subjected to rapid environmental change. We then investigated how empirical host–parasite networks would respond to historical, random and expected extinction sequences. In both the cases, networks were far more robust to historical conditions than new ones, suggesting that new environmental challenges, as expected under global change, might collapse otherwise robust natural ecosystems.

  13. Human impact: man's role in environmental change

    SciTech Connect

    Goudie, A.

    1982-01-01

    Drawing upon worldwide examples, the author traces mankind's interaction with nature and examines human interference with environmental systems at various stages of social development. Succeeding chapters take up man's specific impact on vegetation, animals, the soil, the waters, landforms, climate, and the atmosphere. With the aid of maps, diagrams, and graphs, the book analyzes the causes and consequences of environmental changes associated with such large-scale events as agricultural expansion, domestication, deforestation, and urbanization, including the spread of salination, extinction, erosion, and pollution. Interrelations, often dynamic and unpredictable, between these phenomena make it difficult to isolate the causes of changes and to determine the resiliency of natural systems to change. 505 references, 82 figures, 97 tables.

  14. Future generations, environmental ethics, and global environmental change

    SciTech Connect

    Tonn, B.E.

    1994-12-31

    The elements of a methodology to be employed by the global community to investigate the consequences of global environmental change upon future generations and global ecosystems are outlined in this paper. The methodology is comprised of two major components: A possible future worlds model; and a formal, citizen-oriented process to judge whether the possible future worlds potentially inheritable by future generations meet obligational standards. A broad array of descriptors of future worlds can be encompassed within this framework, including survival of ecosystems and other species and satisfaction of human concerns. The methodology expresses fundamental psychological motivations and human myths journey, renewal, mother earth, and being-in-nature-and incorporates several viewpoints on obligations to future generations-maintaining options, fairness, humility, and the cause of humanity. The methodology overcomes several severe drawbacks of the economic-based methods most commonly used for global environmental policy analysis.

  15. Serial population extinctions in a small mammal indicate Late Pleistocene ecosystem instability.

    PubMed

    Brace, Selina; Palkopoulou, Eleftheria; Dalén, Love; Lister, Adrian M; Miller, Rebecca; Otte, Marcel; Germonpré, Mietje; Blockley, Simon P E; Stewart, John R; Barnes, Ian

    2012-12-11

    The Late Pleistocene global extinction of many terrestrial mammal species has been a subject of intensive scientific study for over a century, yet the relative contributions of environmental changes and the global expansion of humans remain unresolved. A defining component of these extinctions is a bias toward large species, with the majority of small-mammal taxa apparently surviving into the present. Here, we investigate the population-level history of a key tundra-specialist small mammal, the collared lemming (Dicrostonyx torquatus), to explore whether events during the Late Pleistocene had a discernible effect beyond the large mammal fauna. Using ancient DNA techniques to sample across three sites in North-West Europe, we observe a dramatic reduction in genetic diversity in this species over the last 50,000 y. We further identify a series of extinction-recolonization events, indicating a previously unrecognized instability in Late Pleistocene small-mammal populations, which we link with climatic fluctuations. Our results reveal climate-associated, repeated regional extinctions in a keystone prey species across the Late Pleistocene, a pattern likely to have had an impact on the wider steppe-tundra community, and one that is concordant with environmental change as a major force in structuring Late Pleistocene biodiversity.

  16. NOVELTY DETECTION UNDER CHANGING ENVIRONMENTAL CONDITIONS

    SciTech Connect

    H. SOHN; K. WORDER; C. R. FARRAR

    2001-04-01

    The primary objective of novelty detection is to examine a system's dynamic response to determine if the system significantly deviates from an initial baseline condition. In reality, the system is often subject to changing environmental and operation conditions that affect its dynamic characteristics. Such variations include changes in loading, boundary conditions, temperature, and moisture. Most damage diagnosis techniques, however, generally neglect the effects of these changing ambient conditions. Here, a novelty detection technique is developed explicitly taking into account these natural variations of the system in order to minimize false positive indications of true system changes. Auto-associative neural networks are employed to discriminate system changes of interest such as structural deterioration and damage from the natural variations of the system.

  17. The potential of Pleistocene volcanism for constraining the palaeo-environmental history of the Arabian peninsula: 40Ar/39Ar dating of Al Wahbah maar crater, Harrat Kishb, Saudi Arabia.

    NASA Astrophysics Data System (ADS)

    Abdel Wahab, Antar; Stuart, Finlay M.; Abul Maaty, Mostafa; Awad, Hesham; Kafafy, Aziz

    2013-04-01

    The Arabian peninsula is a critical region for early human migration out of Africa. Pleistocene climatic conditions have fluctuated between wet and dry extremes several times and have had a profound effect on environment and, likely, the development of human populations in the region. However, absolute chronological constraints on regional environmental and climatic changes are poor. The western margin of the Arabian peninsula is covered by 180,000 km2 of Cenozoic to Recent lava flows and related volcanic rocks that record palaeo-climatic conditions. Precise dating of these volcanic rocks has the potential to refine the climatic- environmental evolution of the region. We report a detailed geological and geochronological study of Al Wahbah maar crater (~2.2 km diameter, ~250 m deep) in Harrat Kishb, Saudi Arabia. It formed during a phreatomagmatic explosion that dissected a scoria cone on the northern wall of the crater that exposes a dolerite plug that was intruded immediately prior to crater formation. Pillow lavas at the base of the cone demonstrate that the phreatomagmatic eruption occurred during interaction between magma and a shallow lake or river, rather than groundwater. The 40Ar/39Ar age of dolerite plug (1.147 ± 0.004 Ma) reflects the time that Al Wahbah maar crater formed. More importantly it puts a firm date on the presence of abundant surface water. This study provides constraints on the timing of humid climatic conditions in the region and suggests that the Quaternary basaltic volcanism that stretches the length of the western side of the Arabian peninsula may prove to be useful for establishing the timing of palaeoclimatic changes.

  18. Pleistocene paleotemperatures.

    PubMed

    Emiliani, C

    1970-05-15

    The generalized isotopic paleotemperature curve reproduces absolute temperatures to within 1 degrees C; it closely reflects faunal changes; and its time scale is correct to within a very few percent back to at least 175,000 years. The average oxygen isotopic composition of the North American and European ice caps was about -9 per mil.

  19. National Institute for Global Environmental Change

    SciTech Connect

    Werth, G.C.

    1992-04-01

    This document is the Semi-Annual Report of the National Institute for Global Environmental Change for the reporting period July 1 to December 31, 1991. The report is in two parts. Part I presents the mission of the Institute, examples of progress toward that mission, a brief description of the revised management plan, and the financial report. Part II presents the statements of the Regional Center Directors along with progress reports of the projects written by the researchers themselves.

  20. Adaptation Strategies for Global Environmental Change

    NASA Astrophysics Data System (ADS)

    Ojima, D. S.; Corell, R.

    2007-12-01

    The global environmental challenges society faces today are unheralded due to the pace at which human activities are affecting the earth system. The rates of energy consumption, nitrogen use and production, and water use increases each year leading to greater global environmental changes affecting warming of the earth system and loss of ecosystem services. The challenge we face today as a society is the manner and speed at which we can adapt to these changes affecting the ecosystem services we depend upon. Innovative strategies are needed to develop the adaptive management tools to integrate the sectors and science necessary to deal with the complexity of effects. Developing strategies to better guide decision making related to climate change trends into changing weather patterns at meaningful temporal and spatial scales are needed, observations and prognostic analyses of climate related triggers of threshold events in ecosystem dynamics, and transfer of knowledge between science, technology, and decision makers. These strategies need to better integrate science (physical, biological, and social knowledge), engineering, policy, and economics interests to create a framework to develop strategies for adaptation and mitigation to global change and to create bridges with institutions and organizations that deal with these issues as a governmental agency or private sector enterprise.

  1. Nodule performance within a changing environmental context.

    PubMed

    Aranjuelo, Iker; Arrese-Igor, Cesar; Molero, Gemma

    2014-07-15

    Global climate models predict that future environmental conditions will see alterations in temperature, water availability and CO2 concentration ([CO2]) in the atmosphere. Climate change will reinforce the need to develop highly productive crops. For this purpose it is essential to identify target traits conditioning plant performance in changing environments. N2 fixing plants represent the second major crop of agricultural importance worldwide. The current review provides a compilation of results from existing literature on the effects of several abiotic stress conditions on nodule performance and N2 fixation. The environmental factors analysed include water stress, salinity, temperature, and elevated [CO2]. Despite the large number of studies analysing [CO2] effects in plants, frequently they have been conducted under optimal growth conditions that are difficult to find in natural conditions where different stresses often occur simultaneously. This is why we have also included a section describing the current state of knowledge of interacting environmental conditions in nodule functioning. Regardless of the environmental factor considered, it is evident that some general patterns of nodule response are observed. Nodule carbohydrate and N compound availability, together with the presence of oxygen reactive species (ROS) have proven to be the key factors modulating N2 fixation at the physiological/biochemical levels. However, with the exception of water availability and [CO2], it should also be considered that nodule performance has not been characterised in detail under other limiting growth conditions. This highlights the necessity to conduct further studies considering these factors. Finally, we also observe that a better understanding of these metabolic effects of changing environment in nodule functioning would require an integrated and synergistic investigation based on widely used and novel protocols such as transcriptomics, proteomics, metabolomics and

  2. Environmental change and hominin exploitation of C4-based resources in wetland/savanna mosaics.

    PubMed

    Stewart, Kathlyn M

    2014-12-01

    Eastern and southern Africa experienced ongoing climatic and tectonic instability in the Plio-Pleistocene, alongside declining forests and expanding grasslands. Most known hominin genera (Australopithecus spp., Kenyanthropus, Paranthropus spp., Homo spp.) appear roughly between 4.2 and 1.8 Ma (millions of years ago). Explanations for these speciation events have focused on adaptations to environmental change, particularly in terrestrial biomes. However, the links between environmental change and hominin adaptations have not always been clear. Often overlooked is that Plio-Pleistocene vegetation included not just terrestrial environments, but a large component of edaphic (wet) C4 grasses and sedges. In this paper it is suggested that in response to environmental fluctuations, hominins engaged in conservative long-term ecological and dietary patterns, based on predictable C4/C3 wetland and terrestrial resources. Data are presented from six hominin locales, which demonstrate reliance on plant-based resources (sedges, grasses, and other vegetation) in C4-inclusive wetland/savanna mosaics. After roughly 2.4 Ma, severe climate variability is associated with early Homo and perhaps Paranthropus boisei broadening their diet to familiar but less preferred foods: vertebrates and invertebrates. These foods consistently provided early Homo with essential nutrients, which reduced selection pressures and allowed for increases in brain size. After 1.65 Ma, a 20% increase in the C4 dietary component of Homo occurs alongside increased relative brain size. P. boisei also increases its C4 dietary component by 15% after 1.65 Ma. These increases imply that both taxa continued to broaden their diet within the C4-based wetlands/savanna biome, with Homo putting a greater emphasis on mammals.

  3. Environmental change drove macroevolution in cupuladriid bryozoans.

    PubMed

    O'Dea, Aaron; Jackson, Jeremy

    2009-10-22

    Most macroevolutionary events are correlated with changes in the environment, but more rigorous evidence of cause and effect has been elusive. We compiled a 10 Myr record of origination and extinction, changes in mode of reproduction, morphologies and abundances of cupuladriid bryozoan species, spanning the time when primary productivity collapsed in the southwestern Caribbean as the Isthmus of Panama closed. The dominant mode of reproduction shifted dramatically from clonal to aclonal, due in part to a pulse of origination followed by extinction that was strongly selective in favour of aclonal species. Modern-day studies predict reduced clonality in increasingly oligotrophic conditions, thereby providing a mechanistic explanation supporting the hypothesis that the collapse in primary productivity was the cause of turnover. However, whereas originations were synchronous with changing environments, extinctions lagged 1-2 Myr. Extinct species failed to become more robust and reduce their rate of cloning when the new environmental conditions arose, and subsequently saw progressive reductions in abundance towards their delayed demise. Environmental change is therefore established as the root cause of macroevolutionary turnover despite the lag between origination and extinction.

  4. Collective behaviour, uncertainty and environmental change.

    PubMed

    Bentley, R Alexander; O'Brien, Michael J

    2015-11-28

    A central aspect of cultural evolutionary theory concerns how human groups respond to environmental change. Although we are painting with a broad brush, it is fair to say that prior to the twenty-first century, adaptation often happened gradually over multiple human generations, through a combination of individual and social learning, cumulative cultural evolution and demographic shifts. The result was a generally resilient and sustainable population. In the twenty-first century, however, considerable change happens within small portions of a human generation, on a vastly larger range of geographical and population scales and involving a greater degree of horizontal learning. As a way of gauging the complexity of societal response to environmental change in a globalized future, we discuss several theoretical tools for understanding how human groups adapt to uncertainty. We use our analysis to estimate the limits of predictability of future societal change, in the belief that knowing when to hedge bets is better than relying on a false sense of predictability.

  5. Environmental change drove macroevolution in cupuladriid bryozoans

    PubMed Central

    O'Dea, Aaron; Jackson, Jeremy

    2009-01-01

    Most macroevolutionary events are correlated with changes in the environment, but more rigorous evidence of cause and effect has been elusive. We compiled a 10 Myr record of origination and extinction, changes in mode of reproduction, morphologies and abundances of cupuladriid bryozoan species, spanning the time when primary productivity collapsed in the southwestern Caribbean as the Isthmus of Panama closed. The dominant mode of reproduction shifted dramatically from clonal to aclonal, due in part to a pulse of origination followed by extinction that was strongly selective in favour of aclonal species. Modern-day studies predict reduced clonality in increasingly oligotrophic conditions, thereby providing a mechanistic explanation supporting the hypothesis that the collapse in primary productivity was the cause of turnover. However, whereas originations were synchronous with changing environments, extinctions lagged 1–2 Myr. Extinct species failed to become more robust and reduce their rate of cloning when the new environmental conditions arose, and subsequently saw progressive reductions in abundance towards their delayed demise. Environmental change is therefore established as the root cause of macroevolutionary turnover despite the lag between origination and extinction. PMID:19640882

  6. Macroecological analyses support an overkill scenario for late Pleistocene extinctions.

    PubMed

    Diniz-Filho, J A F

    2004-08-01

    The extinction of megafauna at the end of Pleistocene has been traditionally explained by environmental changes or overexploitation by human hunting (overkill). Despite difficulties in choosing between these alternative (and not mutually exclusive) scenarios, the plausibility of the overkill hypothesis can be established by ecological models of predator-prey interactions. In this paper, I have developed a macroecological model for the overkill hypothesis, in which prey population dynamic parameters, including abundance, geographic extent, and food supply for hunters, were derived from empirical allometric relationships with body mass. The last output correctly predicts the final destiny (survival or extinction) for 73% of the species considered, a value only slightly smaller than those obtained by more complex models based on detailed archaeological and ecological data for each species. This illustrates the high selectivity of Pleistocene extinction in relation to body mass and confers more plausibility on the overkill scenario.

  7. Causes of Late Pleistocene water level change in Lake Victoria, Equatorial East Africa, derived from clumped isotopes of land snails and fresh water mollusks. (Invited)

    NASA Astrophysics Data System (ADS)

    Zaarur, S.; Affek, H. P.; Tryon, C.; Peppe, D. J.; Faith, J.

    2013-12-01

    mean annual precipitation that is significantly greater than modern. However, this is inconsistent with regional climate reconstructions. This suggests that either lake level was controlled by non-climatic factors, or that local climate in the Lake Victoria basin was different than regional patterns of climate across eastern Africa. We use oxygen and clumped isotopes of modern and fossil shells (Corbicula sp., Melanoides sp. and Bellamya unicolor) from this 18 m beach outcrop on Mfangano Island to (1) compare with modern lake water δ18O values and (2) calculate paleo-water compositions. We combine these results with calculated snail body water δ18O composition (using oxygen and clumped isotopes) of land snails (Limicoloria cf. martensiana) from Rusinga and Mfangano Islands, to study hydrological changes of Lake Victoria. We use these data to evaluate the relative importance of climate change and tectonics as mechanisms for the Late Pleistocene expansion of Lake Victoria.

  8. What Happened to Gray Whales during the Pleistocene? The Ecological Impact of Sea-Level Change on Benthic Feeding Areas in the North Pacific Ocean

    PubMed Central

    Pyenson, Nicholas D.; Lindberg, David R.

    2011-01-01

    Background Gray whales (Eschrichtius robustus) undertake long migrations, from Baja California to Alaska, to feed on seasonally productive benthos of the Bering and Chukchi seas. The invertebrates that form their primary prey are restricted to shallow water environments, but global sea-level changes during the Pleistocene eliminated or reduced this critical habitat multiple times. Because the fossil record of gray whales is coincident with the onset of Northern Hemisphere glaciation, gray whales survived these massive changes to their feeding habitat, but it is unclear how. Methodology/Principal Findings We reconstructed gray whale carrying capacity fluctuations during the past 120,000 years by quantifying gray whale feeding habitat availability using bathymetric data for the North Pacific Ocean, constrained by their maximum diving depth. We calculated carrying capacity based on modern estimates of metabolic demand, prey availability, and feeding duration; we also constrained our estimates to reflect current population size and account for glaciated and non-glaciated areas in the North Pacific. Our results show that key feeding areas eliminated by sea-level lowstands were not replaced by commensurate areas. Our reconstructions show that such reductions affected carrying capacity, and harmonic means of these fluctuations do not differ dramatically from genetic estimates of carrying capacity. Conclusions/Significance Assuming current carrying capacity estimates, Pleistocene glacial maxima may have created multiple, weak genetic bottlenecks, although the current temporal resolution of genetic datasets does not test for such signals. Our results do not, however, falsify molecular estimates of pre-whaling population size because those abundances would have been sufficient to survive the loss of major benthic feeding areas (i.e., the majority of the Bering Shelf) during glacial maxima. We propose that gray whales survived the disappearance of their primary feeding ground

  9. A 20,000-year record of environmental change from Laguna Kollpa Kkota, Bolivia

    SciTech Connect

    Seltzer, G.O. . Mendenhall Lab.); Abbott, M.B. )

    1992-01-01

    Most records of paleoclimate in the Bolivian Andes date from the last glacial-to-interglacial transition. However, Laguna Kollpa Kkota and other lakes like it, formed more than 20,000 yr BP when glaciers retreated and moraines dammed the drainage of the valleys they are located in. These lakes were protected from subsequent periods of glaciation because the headwalls of these valleys are below the level of the late-Pleistocene glacial equilibrium-line altitude. The chemical, mineral, and microfossil stratigraphies of these glacial lakes provide continuous records of environmental change for the last 20,000 years that can be used to address several problems in paleoclimate specific to tropical-subtropical latitudes. Preliminary results from Laguna Kollpa Kkota indicate that glacial equilibrium-line altitudes were never depressed more than 600 m during the last 20,000 years, suggesting that temperatures were reduced only a few-degrees celsius over this time period. Sedimentation rates and the organic carbon stratigraphy of cores reflect an increase in moisture in the late Pleistocene just prior to the transition to a warmer and drier Holocene. The pollen and diatom concentrations in the sediments are sufficient to permit the high resolution analyses needed to address whether or not there were climatic reversals during the glacial-to-interglacial transition.

  10. The complex behavior of the Cordilleran Ice Sheet and mountain glaciers to abrupt climate change during the latest Pleistocene

    NASA Astrophysics Data System (ADS)

    Menounos, Brian; Goehring, Brent; Osborn, Gerald; Clarke, Garry K. C.; Ward, Brent; Margold, Martin; Bond, Jeff; Clague, John J.; Lakeman, Tom; Schaefer, Joerg; Koch, Joe; Gosse, John; Stroeven, Arjen P.; Seguinot, Julien; Heyman, Jakob; Fulton, Robert

    2014-05-01

    Surficial mapping and more than 70 radiometric ages 10Be, 14C] constrain the evolution of the Cordilleran Ice Sheet (CIS) and associated mountain glaciers in western Canada during the latest Pleistocene. Our data suggest that: i) there is widespread evidence for the Younger Dryas (YD) throughout the mountains of western Canada; ii) late Pleistocene climate reconstructions based solely on alpine moraines may be misleading in regions with decaying ice sheets; iii) extensive interfluves in some mountain regions were ice-free between 16 ka and 13 ka (kilo calibrated yrs BP). Initial decay of the CIS from its maximum extent around 16 ka was likely due to a combination of climatic (surface melting) and dynamical factors. Climate amelioration during the Bølling-Allerød Warm Period [14.7-12.9 ka], likely the cause for the major phase of CIS decay, resulted in ice sheet equilibrium line altitudes (ELAs) ranging from 2500 m asl in southern BC to around 2000 m asl along the BC-Yukon border. Hence, before the onset of the Younger Dryas (YD) Cold Period [12.9-11.7 ka], the ice sheet shrank and became a labyrinth of individual and coalescing valley glaciers fed by major accumulation zones centered on the Coast Mountains and other high ranges of NW Canada. The response of remnant ice and cirque glaciers to the YD climate deterioration was highly variable. In some cases, small glaciers (0.5-2 km2) built YD moraines that were only hundreds of meters beyond those constructed during the Little Ice Age (LIA) [0.30-0.15 ka]. Our dating also reveals that much larger glaciers persisted in nearby valleys that lie hundreds of meters below the cirques. Hence, we infer that many cirques were completely deglaciated prior the YD, in contrast to low-lying valleys where ice sheet remnants persisted. Glaciers also advanced in north-central British Columbia during the YD, but here glaciers constructed large terminal and lateral moraines. In the Cassiar and northern Coast mountains, for example

  11. Oxygen isotope measurements of mammoth and reindeer skeletal remains: an archive of Late Pleistocene environmental conditions in Eurasian Arctic

    NASA Astrophysics Data System (ADS)

    Genoni, L.; Iacumin, P.; Nikolaev, V.; Gribchenko, Yu.; Longinelli, A.

    1998-08-01

    58 samples of fossil mammoth and reindeer teeth and bones of various ages and coming from different locations were studied for the oxygen isotopic composition of their phosphate. Samples from Siberia have interstadial (Marine Isotope Stage 3), stadial (MIS 2), late-glacial and post-glacial ages. Russian and Ukrainian samples refer to the late-glacial and transitional (between the interstadial and glacial stages) time. The δ18O of palaeoenvironmental waters were calculated from the δ18O p obtained from fossil samples by means of the isotope equations calibrated on modern specimens of elephants and deer respectively. The δ18O w obtained are generally lighter than those measured nowadays in the same areas and not far from those measured on ice cores of Holocene age, the isotopic differences being not greater than a few δ units. The calculated values are also in fairly good agreement with some isotopic values obtained from Siberian permafrost samples. According to the results obtained it seems that the elephant and deer equations can be reasonably used respectively in the case of fossil mammoth and deer skeletons to evaluate environmental palaeowaters.

  12. Chronological and environmental context of the Middle Pleistocene human tooth from Mollet Cave (Serinyà, NE Iberian Peninsula).

    PubMed

    Maroto, Julià; Julià, Ramon; López-García, Juan Manuel; Blain, Hugues-Alexandre

    2012-06-01

    Mollet Cave is a small cave situated in Serinyà (north-east Iberian Peninsula). It was excavated in 1947-48, 1958 and 1972 by Josep M. Corominas. An archaic human molar comes from its base layer (Layer 5). Up till now, this layer has only been dated based on a relative and imprecise chronology of macromammals and the archaeostratigraphic evidence from the early excavations. Recent excavations, conducted between 2001 and 2005, have made it possible to ascertain more precisely the archaeological and palaeontological contents of Mollet Cave, gather microvertebrates, and collect samples for radiometric dating. The aim of this paper is to present the absolute dating of Layer 5, as well as its palaeo environmental and climatic characterisation. The macromammal assemblage seems to have been the result of accumulations produced by the most abundant carnivore, the hyena, which would have used the cave as a den. The results obtained using uranium-series disequilibrium dating ascribe to Layer 5 an age of ca. 215 ka (thousands of years ago), which would correspond to MIS 7. The faunal association suggests a landscape formed by an open and humid woodland characteristic of an interstadial phase, which would have been an environment well suited to sustaining both hyenas and human groups.

  13. Comparative phylogeography of two marine species of crustacean: Recent divergence and expansion due to environmental changes.

    PubMed

    Zhang, Daizhen; Ding, Ge; Ge, Baoming; Zhang, Huabin; Tang, Boping; Yang, Guang

    2014-10-15

    Environmental changes, such as changes in the coastal topography due to Eurasian plate movements, climate oscillation during the Pleistocene, and alteration of ocean currents, have complicated the geographical structure of marine species and deepened their divergence between populations. As two widely distributed species of crustacean (Oratosquilla oratoria and Eriocheir japonica), weak differences were expected due to their high dispersal potential of planktonic larvae with ocean currents. However, results showed a significant genetic divergence between north of China and south of China in the study. In addition, the estimated north-south divergence time (27-30.5 Myr) of mantis shrimp was near the time of the Himalayan movement, and the China-Japan clade divergence time (10.5-11.9 Myr) of mitten crabs was also coincident with the time of the opening of the Sea of Japan. Thus, we hypothesized that environmental changes in the coastal topography contributed to the marine species divergence. Furthermore, based on phylogenetic analysis, network analysis and haplotype distribution, we surmised that mitten crabs originated from a population with the oldest haplotype (H6) and then divided into the north and south populations due to the recent Eurasian plate movements and ocean currents. And lineage of Japan originated from the north population for the opening of the Sea of Japan. While O. oratoria was guessed to originate from two separate populations in the China Sea. The results of "star-like" network, negative values in neutral test, and Tajima's D statistics of two marine species supported a recent rapid population expansion event after the Pleistocene glaciations.

  14. A multilocus evaluation of ermine (Mustela erminea) across the Holarctic, testing hypotheses of Pleistocene diversification in response to climate change

    USGS Publications Warehouse

    Dawson, Natalie G.; Hope, Andrew G.; Talbot, Sandra L.; Cook, Joseph A.

    2013-01-01

    Aim: We examined data for ermine (Mustela erminea) to test two sets of diversification hypotheses concerning the number and location of late Pleistocene refugia, the timing and mode of diversification, and the evolutionary influence of insularization. Location: Temperate and sub-Arctic Northern Hemisphere. Methods: We used up to two mitochondrial and four nuclear loci from 237 specimens for statistical phylogeographical and demographic analyses. Coalescent species-tree estimation used a Bayesian approach for clade divergence based on external mutation rate calibrations. Approximate Bayesian methods were used to assess population size, timing of divergence and gene flow. Results: Limited structure coupled with evidence of population growth across broad regions, including previously ice-covered areas, indicated expansion from multiple centres of differentiation, but high endemism along the North Pacific coast (NPC). A bifurcating model of diversification with recent growth spanning three glacial cycles best explained the empirical data. Main conclusions: A newly identified clade in North America indicated a fourth refugial area for ermine. The shallow coalescence of all extant ermine reflects a recent history of diversification overlying a deeper fossil record. Post-glacial colonization has led to potential contact zones for multiple lineages in north-western North America. A model of diversification of ermine accompanied by recent gene flow was marginally less well supported than a model of divergence of major clades in response to the most recent glacial cycles.

  15. (40)Ar/(39)Ar dating of Bed I, Olduvai Gorge, Tanzania, and the chronology of early Pleistocene climate change.

    PubMed

    Deino, Alan L

    2012-08-01

    (40)Ar/(39)Ar dating of tuffs and lavas of the late Pleistocene volcanic and sedimentary sequence of Olduvai Gorge, north-central Tanzania, provides the basis for a revision of Bed I chronostratigraphy. Bed I extends from immediately above the Naabi Ignimbrite at 2.038 ± 0.005 Ma to Tuff IF at 1.803 ± 0.002 Ma. Tuff IB, a prominent widespread marker tuff in the basin and a key to understanding hominin evolutionary chronologies and paleoclimate histories, has an age of 1.848 ± 0.003 Ma. The largest lake expansion event in the closed Olduvai lake basin during Bed I times encompassed the episode of eruption and emplacement of this tuff. This lake event is nearly coincident with the maximum precessional insolation peak of the entire Bed I/Lower Bed II interval, calculated from an astronomical model of the boreal summer orbital insolation time-series. The succeeding precessional peak also apparently coincides with the next youngest expansion of paleo-Lake Olduvai. The extreme wet/dry climate shifts seen in the upper part of Bed I occur during an Earth-orbital eccentricity maximum, similar to episodic lake expansions documented elsewhere in the East African Rift during the Neogene.

  16. The role of cryptotephra in refining the chronology of Late Pleistocene human evolution and cultural change in North Africa

    NASA Astrophysics Data System (ADS)

    Barton, R. N. E.; Lane, C. S.; Albert, P. G.; White, D.; Collcutt, S. N.; Bouzouggar, A.; Ditchfield, P.; Farr, L.; Oh, A.; Ottolini, L.; Smith, V. C.; Van Peer, P.; Kindermann, K.

    2015-06-01

    Sites in North Africa hold key information for dating the presence of Homo sapiens and the distribution of Middle Stone Age (MSA), Middle Palaeolithic (MP) and Later Stone Age (LSA) cultural activity in the Late Pleistocene. Here we present new and review recently published tephrochronological evidence for five cave sites in North Africa with long MSA/MP and LSA cultural sequences. Four tephra horizons have been identified at the Haua Fteah (Cyrenaica, Libya). They include cryptotephra evidence for the Campanian Ignimbrite (CI) eruption dating to ˜39 ka that allows correlation with other Palaeolithic sequences in the eastern Mediterranean and as far north as Russia. Cryptotephra have also been recorded from the Moroccan sites of Taforalt, Rhafas and Dar es-Soltane 1. At Taforalt the geochemical composition suggests a provenance in the Azores, while examples from Sodmein (Egypt) appear to derive from central Anatolia and another unknown source. In these latter examples chemical compositional data from relevant proximal volcanic centres is currently lacking so the identification of tephra in layers of known age and cultural association provides the first reliable age determinations for distal volcanic events and their geographical extent. The future potential for tephrochronological research in North Africa is also discussed.

  17. Environmental health implications of global climate change.

    PubMed

    Watson, Robert T; Patz, Jonathan; Gubler, Duane J; Parson, Edward A; Vincent, James H

    2005-09-01

    This paper reviews the background that has led to the now almost-universally held opinion in the scientific community that global climate change is occurring and is inescapably linked with anthropogenic activity. The potential implications to human health are considerable and very diverse. These include, for example, the increased direct impacts of heat and of rises in sea level, exacerbated air and water-borne harmful agents, and--associated with all the preceding--the emergence of environmental refugees. Vector-borne diseases, in particular those associated with blood-sucking arthropods such as mosquitoes, may be significantly impacted, including redistribution of some of those diseases to areas not previously affected. Responses to possible impending environmental and public health crises must involve political and socio-economic considerations, adding even greater complexity to what is already a difficult challenge. In some areas, adjustments to national and international public health practices and policies may be effective, at least in the short and medium terms. But in others, more drastic measures will be required. Environmental monitoring, in its widest sense, will play a significant role in the future management of the problem.

  18. Multilocus phylogeography of a widespread savanna-woodland-adapted rodent reveals the influence of Pleistocene geomorphology and climate change in Africa's Zambezi region.

    PubMed

    McDonough, Molly M; Šumbera, Radim; Mazoch, Vladimír; Ferguson, Adam W; Phillips, Caleb D; Bryja, Josef

    2015-10-01

    Understanding historical influences of climate and physiographic barriers in shaping patterns of biodiversity remains limited for many regions of the world. For mammals of continental Africa, phylogeographic studies, particularly for West African lineages, implicate both geographic barriers and climate oscillations in shaping small mammal diversity. In contrast, studies for southern African species have revealed conflicting phylogenetic patterns for how mammalian lineages respond to both climate change and geologic events such as river formation, especially during the Pleistocene. However, these studies were often biased by limited geographic sampling or exclusively focused on large-bodied taxa. We exploited the broad southern African distribution of a savanna-woodland-adapted African rodent, Gerbilliscus leucogaster (bushveld gerbil) and generated mitochondrial, autosomal and sex chromosome data to quantify regional signatures of climatic and vicariant biogeographic phenomena. Results indicate the most recent common ancestor for all G. leucogaster lineages occurred during the early Pleistocene. We documented six divergent mitochondrial lineages that diverged ~0.270-0.100 mya, each of which was geographically isolated during periods characterized by alterations to the course of the Zambezi River and its tributaries as well as regional 'megadroughts'. Results demonstrate the presence of a widespread lineage exhibiting demographic expansion ~0.065-0.035 mya, a time that coincides with savanna-woodland expansion across southern Africa. A multilocus autosomal perspective revealed the influence of the Kafue River as a current barrier to gene flow and regions of secondary contact among divergent mitochondrial lineages. Our results demonstrate the importance of both climatic fluctuations and physiographic vicariance in shaping the distribution of southern African biodiversity.

  19. Forecasting sudden changes in environmental pollution patterns

    PubMed Central

    Olascoaga, María J.; Haller, George

    2012-01-01

    The lack of reliable forecasts for the spread of oceanic and atmospheric contamination hinders the effective protection of the ecosystem, society, and the economy from the fallouts of environmental disasters. The consequences can be dire, as evidenced by the Deepwater Horizon oil spill in the Gulf of Mexico in 2010. We present a methodology to predict major short-term changes in environmental contamination patterns, such as oil spills in the ocean and ash clouds in the atmosphere. Our approach is based on new mathematical results on the objective (frame-independent) identification of key material surfaces that drive tracer mixing in unsteady, finite-time flow data. Some of these material surfaces, known as Lagrangian coherent structures (LCSs), turn out to admit highly attracting cores that lead to inevitable material instabilities even under future uncertainties or unexpected perturbations to the observed flow. These LCS cores have the potential to forecast imminent shape changes in the contamination pattern, even before the instability builds up and brings large masses of water or air into motion. Exploiting this potential, the LCS-core analysis developed here provides a model-independent forecasting scheme that relies only on already observed or validated flow velocities at the time the prediction is made. We use this methodology to obtain high-precision forecasts of two major instabilities that occurred in the shape of the Deepwater Horizon oil spill. This is achieved using simulated surface currents preceding the prediction times and assuming that the oil behaves as a passive tracer. PMID:22411824

  20. Late Pleistocene climate change and landscape dynamics in the Eastern Alps: the inner-alpine Unterangerberg record (Austria)

    PubMed Central

    Starnberger, Reinhard; Drescher-Schneider, Ruth; Reitner, Jürgen M.; Rodnight, Helena; Reimer, Paula J.; Spötl, Christoph

    2013-01-01

    Drill cores from the inner-alpine valley terrace of Unterangerberg, located in the Eastern Alps of Austria, offer first insights into a Pleistocene sedimentary record that was not accessible so far. The succession comprises diamict, gravel, sand, lignite and thick, fine grained sediments. Additionally, cataclastic deposits originating from two paleo-landslide events are present. Multi-proxy analyses including sedimentological and palynological investigations as well as radiocarbon and luminescence data record the onset of the last glacial period (Würmian) at Unterangerberg at ∼120–110 ka. This first time period, correlated to the MIS 5d, was characterised by strong fluvial aggradation under cold climatic conditions, with only sparse vegetation cover. Furthermore, two large and quasi-synchronous landslide events occurred during this time interval. No record of the first Early Würmian interstadial (MIS 5c) is preserved. During the second Early Würmian interstadial (MIS 5a), the local vegetation was characterised by a boreal forest dominated by Picea, with few thermophilous elements. The subsequent collapse of the vegetation is recorded by sediments dated to ∼70–60 ka (i.e. MIS 4), with very low pollen concentrations and the potential presence of permafrost. Climatic conditions improved again between ∼55 and 45 ka (MIS 3) and cold-adapted trees re-appeared during interstadials, forming an open forest vegetation. MIS 3 stadials were shorter and less severe than the MIS 4 at Unterangerberg, and vegetation during these cold phases was mainly composed of shrubs, herbs and grasses, similar to what is known from today's alpine timberline. The Unterangerberg record ended at ∼45 ka and/or was truncated by ice during the Last Glacial Maximum. PMID:23805019

  1. Late Pleistocene climate change and landscape dynamics in the Eastern Alps: the inner-alpine Unterangerberg record (Austria).

    PubMed

    Starnberger, Reinhard; Drescher-Schneider, Ruth; Reitner, Jürgen M; Rodnight, Helena; Reimer, Paula J; Spötl, Christoph

    2013-05-15

    Drill cores from the inner-alpine valley terrace of Unterangerberg, located in the Eastern Alps of Austria, offer first insights into a Pleistocene sedimentary record that was not accessible so far. The succession comprises diamict, gravel, sand, lignite and thick, fine grained sediments. Additionally, cataclastic deposits originating from two paleo-landslide events are present. Multi-proxy analyses including sedimentological and palynological investigations as well as radiocarbon and luminescence data record the onset of the last glacial period (Würmian) at Unterangerberg at ∼120-110 ka. This first time period, correlated to the MIS 5d, was characterised by strong fluvial aggradation under cold climatic conditions, with only sparse vegetation cover. Furthermore, two large and quasi-synchronous landslide events occurred during this time interval. No record of the first Early Würmian interstadial (MIS 5c) is preserved. During the second Early Würmian interstadial (MIS 5a), the local vegetation was characterised by a boreal forest dominated by Picea, with few thermophilous elements. The subsequent collapse of the vegetation is recorded by sediments dated to ∼70-60 ka (i.e. MIS 4), with very low pollen concentrations and the potential presence of permafrost. Climatic conditions improved again between ∼55 and 45 ka (MIS 3) and cold-adapted trees re-appeared during interstadials, forming an open forest vegetation. MIS 3 stadials were shorter and less severe than the MIS 4 at Unterangerberg, and vegetation during these cold phases was mainly composed of shrubs, herbs and grasses, similar to what is known from today's alpine timberline. The Unterangerberg record ended at ∼45 ka and/or was truncated by ice during the Last Glacial Maximum.

  2. Energy flow and functional compensation in Great Basin small mammals under natural and anthropogenic environmental change

    PubMed Central

    Terry, Rebecca C.; Rowe, Rebecca J.

    2015-01-01

    Research on the ecological impacts of environmental change has primarily focused at the species level, leaving the responses of ecosystem-level properties like energy flow poorly understood. This is especially so over millennial timescales inaccessible to direct observation. Here we examine how energy flow within a Great Basin small mammal community responded to climate-driven environmental change during the past 12,800 y, and use this baseline to evaluate responses observed during the past century. Our analyses reveal marked stability in energy flow during rapid climatic warming at the terminal Pleistocene despite dramatic turnover in the distribution of mammalian body sizes and habitat-associated functional groups. Functional group turnover was strongly correlated with climate-driven changes in regional vegetation, with climate and vegetation change preceding energetic shifts in the small mammal community. In contrast, the past century has witnessed a substantial reduction in energy flow caused by an increase in energetic dominance of small-bodied species with an affinity for closed grass habitats. This suggests that modern changes in land cover caused by anthropogenic activities—particularly the spread of nonnative annual grasslands—has led to a breakdown in the compensatory dynamics of energy flow. Human activities are thus modifying the small mammal community in ways that differ from climate-driven expectations, resulting in an energetically novel ecosystem. Our study illustrates the need to integrate across ecological and temporal scales to provide robust insights for long-term conservation and management. PMID:26170294

  3. Changing Learner Behavior through Environmental Education.

    ERIC Educational Resources Information Center

    Hungerford, Harold R.; Volk, Trudi L.

    1990-01-01

    Addressed is the effectiveness of environmental education for promoting responsible citizenship behavior. A model of environmental citizenship behavior is presented. Goals for instruction in environmental education are discussed. (CW)

  4. Amphibians as models for studying environmental change.

    PubMed

    Hopkins, William A

    2007-01-01

    The use of amphibians as models in ecological research has a rich history. From an early foundation in studies of amphibian natural history sprang generations of scientists who used amphibians as models to address fundamental questions in population and community ecology. More recently, in the wake of an environment that human disturbances rapidly altered, ecologists have adopted amphibians as models for studying applied ecological issues such as habitat loss, pollution, disease, and global climate change. Some of the characteristics of amphibians that make them useful models for studying these environmental problems are highlighted, including their trophic importance, environmental sensitivity, research tractability, and impending extinction. The article provides specific examples from the recent literature to illustrate how studies on amphibians have been instrumental in guiding scientific thought on a broad scale. Included are examples of how amphibian research has transformed scientific disciplines, generated new theories about global health, called into question widely accepted scientific paradigms, and raised awareness in the general public that our daily actions may have widespread repercussions. In addition, studies on amphibian declines have provided insight into the complexity in which multiple independent factors may interact with one another to produce catastrophic and sometimes unpredictable effects. Because of the complexity of these problems, amphibian ecologists have been among the strongest advocates for interdisciplinary research. Future studies of amphibians will be important not only for their conservation but also for the conservation of other species, critical habitats, and entire ecosystems.

  5. Reconstructed glacier geometry and inferred Equilibrium Line Altitude changes during the Late Pleistocene deglaciation in the Retezat Mountains, Southern Carpathians

    NASA Astrophysics Data System (ADS)

    Madarász, Balázs; Ruszkiczay-Rüdiger, Zsófia; Kern, Zoltán; Urdea, Petru

    2016-04-01

    Quaternary glaciations had a major imprint on the landscape and topography of the Southern Carpathians. Their transitional position between continental and Mediterranean climate zones arouses special interest concerning the timing and pattern of glaciations in this area. Probably the Retezat Mts hosted the most extended glaciation during the Late Pleistocene within this range. The peak elevations of the study area reach 2500 m asl, and the most extended glaciers descended to 1040 m in the northern and to 1130 m on the southern valleys. Major cirque floors are typically situated at 2000-2100 m asl. Glacial landforms have been mapped in order to reconstruct the past ice bodies and the elevation shifts of the paleo equilibrium line altitudes (ELA) during several deglaciation phases of the Last Glacial Maximum (LGM) and Lateglacial in the Retezat Mts. On the basis of published 10Be exposure age data on the northern valleys of the study area, deglaciation of the Retezat Mts occurred at least in five phases between ~21.0 ka and 13.5 ka [1]. Various methods (THAR, AAR, AABR) have been tested using a GIS tool to estimate the ELA of the reconstructed paleoglaciers [2] and paleo ELAs were calculated for each of the deglaciation phases. Preliminary estimates of regional LGM paleoELA employing the simplest THAR method (with a ratio of 0.5) ranged from ~1670 m during the LGM to ~2210 m for the smallest cirque glacier at 13.5 ka, respectively. The AAR and AABR methods provide somewhat higher ELAs for each phase. The obtained paleoELAs were compared to ELA reconstructions available from other Carpathian ranges and also to the Alps and Dinarides. Our data will contribute to a more accurate ELA distribution during the LGM, which may be indicative of the past state of the climate system (moisture gradient, circulation regimes). Thanks to OTKA PD83610, PD104899; NKM-96/2014, NKM-31/2015; OMAA 90öu17; LP2012-27/2012. References: [1] Ruszkiczay-Rüdiger et al. 2016 Quat. Int. (in

  6. Environmental groups fault climate-change plan

    SciTech Connect

    Zurer, P.

    1994-05-09

    The Clinton Administration's Climate Change Action Plan will fall far short of its goal for stabilizing greenhouse gas emissions, according to critics from environmental groups. But the White House defends its approach to global warming as a unique partnership between industry and government. The plan, unveiled by President Clinton last fall, aims to limit US emissions of greenhouse gases to no greater than 1990 levels by 2000. It relies on mostly voluntary programs and increased support for renewable energy sources to cut emissions of carbon dioxide, methane, nitrous oxide, hydrofluorocarbons (HFCs), and other gases that contribute to global warming. The Clinton Administration's plan relies for the most part on pledges by industry and utilities to cut emissions. It will save energy and save businesses money while creating jobs.

  7. Introduction to Holocene environmental change in Kamchatka

    NASA Astrophysics Data System (ADS)

    Brooks, S. J.; Diekmann, B.; Jones, V. J.; Hammarlund, D.

    2015-11-01

    This volume brings together a collection of papers on Holocene environmental change in the Kamchatka Peninsula, in the Russian Far East. Much of the work that appears in these papers was completed under the auspices of two major research activities: a UK NERC-funded project Influence of global teleconnections on Holocene climate in Kamchatka, which dealt with the analysis of lake records collected during the Swedish Beringia 2005 expedition organised by the Swedish Polar Research Secretariat; and a Russian-German multidisciplinary research project KALMAR - Kurile-Kamchatka and Aleutian Marginal Sea-Island Arc Systems: Geodynamic and Climate Interaction in Space and Time, funded by the German Federal Ministry of Education and Research (BMBF).

  8. Middle to Late Pleistocene ice extents, tephrochronology and paleoenvironments of the White River area, southwest Yukon

    NASA Astrophysics Data System (ADS)

    Turner, Derek G.; Ward, Brent C.; Bond, Jeffrey D.; Jensen, Britta J. L.; Froese, Duane G.; Telka, Alice M.; Zazula, Grant D.; Bigelow, Nancy H.

    2013-09-01

    Sedimentary deposits from two Middle to Late Pleistocene glaciations and intervening non-glacial intervals exposed along the White River in southwest Yukon, Canada, provide a record of environmental change for much of the past 200 000 years. The study sites are beyond the Marine Isotope stage (MIS) 2 glacial limit, near the maximum regional extent of Pleistocene glaciation. Non-glacial deposits include up to 25 m of loess, peat and gravel with paleosols, pollen, plant and insect macrofossils, large mammal fossils and tephra beds. Finite and non-finite radiocarbon dates, and twelve different tephra beds constrain the chronology of these deposits. Tills correlated to MIS 4 and 6 represent the penultimate and maximum Pleistocene glacial limits, respectively. The proximity of these glacial limits to each other, compared to limits in central Yukon, suggests precipitation conditions were more consistent in southwest Yukon than in central Yukon during the Pleistocene. Conditions in MIS 5e and 5a are recorded by two boreal forest beds, separated by a shrub birch tundra, that indicate environments as warm or warmer than present. A dry, treeless steppe-tundra, dominated by Artemisia frigida, upland grasses and forbs existed during the transition from late MIS 3 to early MIS 2. These glacial and non-glacial deposits constrain the glacial limits and paleoenvironments during the Middle to Late Pleistocene in southwest Yukon.

  9. Indicators of recent environmental change in Alaska

    SciTech Connect

    Jacoby, G.C.; D`Arrigo, R.D.; Juday, G.

    1997-12-31

    Climate models predict that global warming due to the effects of increasing trace gases will be amplified in northern high latitude regions, including Alaska. Several environmental indicators, including tree-ring based temperature reconstructions, borcal forest growth measurements and observations of glacial retreat all indicate that the general warming of the past century has been significant relative to prior centuries to millenia. The tree-ring records for central and northern Alaska indicate that annual temperature increased over the past century, peaked in the 1940s, and are still near the highest level for the past three centuries (Jacoby and D`Arrigo 1995). The tree-ring analyses also suggest that drought stress may now be a factor limiting growth at many northern sites. The recent warming combined with drier years may be altering the response of tree growth to climate and raising the likelihood of forest changes in Alaska and other boreal forests. Other tree-ring and forest data from southern and interior Alaska provide indices of the response of vegetation to extreme events (e.g., insect outbreaks, snow events) in Alaska (Juday and marler 1996). Historical maps, field measurements and satellite imagery indicate that Alaskan glaciers have receded over the past century (e.g., Hall and Benson 1996). Severe outbreaks of bark beetles may be on the increase due to warming, which can shorten their reproductive cycle. Such data and understanding of causes are useful for policy makers and others interested in evaluation of possible impacts of trace-gas induced warming and environmental change in the United States.

  10. Conclusions: environmental change, wildlife conservation and reproduction.

    PubMed

    Holt, William V; Brown, Janine L; Comizzoli, Pierre

    2014-01-01

    Our intention when planning this book was to explore the diverse ways that reproductive science is inextricably tied to many aspects of biodiversity conservation, using the opportunity to present a vast amount of specialised information in a way that forms a coherent and important body of work. Some of the chapters were therefore concerned with understanding how taxonomic groups and species are being affected by globally important environmental changes, mostly caused through anthropogenic influences. Others were more focused on monitoring and understanding the physiology of wild species, with the aim of better understanding mechanisms underlying responses to captive conditions and environmental change, in both wild and captive animals. We also wanted to review advances in technological measures that are being actively developed to support the breeding and management of wildlife. In a few cases we have presented specific case studies that highlight the amount of effort required for the successful development of assisted reproductive technologies for wild species. Viewed overall, the outcome is spectacular; the last decade has seen enormous progress in many aspects of the sciences and technologies relevant to the topic. It is also clear that the boundaries between different scientific disciplines are becoming ever more blurred, and it is no longer easy or even possible to remain focused on a highly specialized topic in reproduction or conservation, without having at least some understanding of allied subjects. Here we present a few concluding comments about what we have learnt, and how the various topics interact with each other. We also emphasize that, as far as we know, no similarly comprehensive consideration of the contribution of reproductive science to wildlife conservation has been published within the last decade.

  11. Holocene environmental change in Kamchatka: A synopsis

    NASA Astrophysics Data System (ADS)

    Brooks, S. J.; Diekmann, B.; Jones, V. J.; Hammarlund, D.

    2015-11-01

    We present a synthesis of the results of a multiproxy, multisite, palaeoecological study of Holocene environmental change in Kamchatka, Far East Russia, details of which are presented elsewhere in the volume. We summarise the results of the analyses of pollen, diatom, chironomid, and testate amoebae assemblages, together with stable isotopes of oxygen and carbon, and sediment characteristics from the sediments of five lakes and a peat succession on a latitudinal gradient of the Kamchatka Peninsula, to infer environmental change and establish the major climate forcers and climatic teleconnections. There are synchronous shifts in the assemblage composition of most of the biota and across most sites at 6.5-6.2 ka BP, 5.2 ka BP, 4.0 ka BP, and 3.5 ka BP, suggesting a response to strong regional climate forcing at these times. These dates correspond to the warmest part of the Holocene Thermal Maximum (HTM) (6.5-6.2 ka BP), the beginning of the Neoglacial cooling (5.2 ka BP), the coolest and wettest part of the Neoglacial (4.0 ka BP), and a switch to warmer and drier conditions at 3.5 ka BP. Our results provide evidence for the penetration and domination of different air masses at different periods during the Holocene. Cool and dry periods in winter (e.g., at 6.0 ka BP) were driven by a relatively weak pressure gradient between the Siberian High and the Aleutian Low, whereas cool, wet periods in winter (e.g., the Neoglacial and during the LIA) developed when these two systems increased in strength. Warm, dry, continental periods in summer (e.g., at 2.5 ka BP) were driven by a weakening of the Siberian High. We find that the timing of the HTM in Kamchatka is later than in the Eurasian arctic but similar to northern Europe and the sub-arctic part of eastern Siberia. This progressive onset of the HTM was due to the effects of postglacial ice-sheet decay that modulated the routes of westerly storm tracks in Eurasia. A major ecosystem driver was the Siberian dwarf pine Pinus

  12. Paleomagnetic and Environmental Magnetic Insights into the Middle to Late Pleistocene Stratigraphy of the 8o North Bengal Fan Transect, IODP Expedition 354

    NASA Astrophysics Data System (ADS)

    Reilly, B. T.; Selkin, P. A.; Meynadier, L.; Savian, J. F.; Weber, M. E.; Schwenk, T.; Spiess, V.; Stoner, J. S.; France-Lanord, C.; Klaus, A.

    2015-12-01

    IODP Expedition 354 cored seven sites along a ~320 km transect of the Bengal Fan at 8o N. Assessing the Pleistocene fan development and depocenter migration in the upper 150-220 m of the Bengal Fan was a primary goal of this expedition. Because any one site includes local variations in depositional processes, the transect approach and accurate stratigraphic correlation of sites is essential to understand overall fan development. Within this transect framework, integrating sediment fluxes across the fan allows for reconstruction of regional climate and tectonic signals through time. A hemipelagic unit deposited at ~1-2.5 cm/ka late in the Matuyama Chron, recording both the Cobb Mountain (1.173 - 1.185 Ma) and Jaramillo (0.988 - 1.072 Ma) Subchrons, was observed at all sites across the transect. This hemipelagic unit provides robust correlation between core derived chronologies and seismic imaging in the Middle Pleistocene. Correlation and orbital tuning of distinctive variations in physical properties (e.g. sediment lightness, wet-bulk density, and magnetic susceptibility) relative to paleomagnetic reversals indicate that turbidite deposition immediately below the base of this unit ceased relatively synchronously across the transect and turbidite deposition likely occurred elsewhere on the fan. The upper bound of the unit, however, is diachronous, with the timing of the onset of turbidite deposition in this part of the fan likely related to the infilling of accommodation space on the Middle Pleistocene fan surface. Stratigraphic constraints on the resumption of turbidite deposition to transect sites include the upper Jaramillo (0.988 Ma) and Matuyama-Bruhnes (0.780 Ma) polarity boundaries and the Oldest Toba Tephra (~0.800 ± 0.020 Ma). The Middle Pleistocene hemipelagic layer and directly overlying turbidites were continuously sampled (u-channels) during Expedition 354. We present initial u-channel magnetic and XRF results to refine the middle to late Pleistocene

  13. The impact of Pleistocene climate change on an ancient arctic-alpine plant: multiple lineages of disparate history in Oxyria digyna.

    PubMed

    Allen, Geraldine A; Marr, Kendrick L; McCormick, Laurie J; Hebda, Richard J

    2012-03-01

    The ranges of arctic-alpine species have shifted extensively with Pleistocene climate changes and glaciations. Using sequence data from the trnH-psbA and trnT-trnL chloroplast DNA spacer regions, we investigated the phylogeography of the widespread, ancient (>3 million years) arctic-alpine plant Oxyria digyna (Polygonaceae). We identified 45 haplotypes and six highly divergent major lineages; estimated ages of these lineages (time to most recent common ancestor, T(MRCA)) ranged from ∼0.5 to 2.5 million years. One lineage is widespread in the arctic, a second is restricted to the southern Rocky Mountains of the western United States, and a third was found only in the Himalayan and Altai regions of Asia. Three other lineages are widespread in western North America, where they overlap extensively. The high genetic diversity and the presence of divergent major cpDNA lineages within Oxyria digyna reflect its age and suggest that it was widespread during much of its history. The distributions of individual lineages indicate repeated spread of Oxyria digyna through North America over multiple glacial cycles. During the Last Glacial Maximum it persisted in multiple refugia in western North America, including Beringia, south of the continental ice, and within the northern limits of the Cordilleran ice sheet. Our data contribute to a growing body of evidence that arctic-alpine species have migrated from different source regions over multiple glacial cycles and that cryptic refugia contributed to persistence through the Last Glacial Maximum.

  14. The impact of Pleistocene climate change on an ancient arctic–alpine plant: multiple lineages of disparate history in Oxyria digyna

    PubMed Central

    Allen, Geraldine A; Marr, Kendrick L; McCormick, Laurie J; Hebda, Richard J

    2012-01-01

    The ranges of arctic–alpine species have shifted extensively with Pleistocene climate changes and glaciations. Using sequence data from the trnH-psbA and trnT-trnL chloroplast DNA spacer regions, we investigated the phylogeography of the widespread, ancient (>3 million years) arctic–alpine plant Oxyria digyna (Polygonaceae). We identified 45 haplotypes and six highly divergent major lineages; estimated ages of these lineages (time to most recent common ancestor, TMRCA) ranged from ∼0.5 to 2.5 million years. One lineage is widespread in the arctic, a second is restricted to the southern Rocky Mountains of the western United States, and a third was found only in the Himalayan and Altai regions of Asia. Three other lineages are widespread in western North America, where they overlap extensively. The high genetic diversity and the presence of divergent major cpDNA lineages within Oxyria digyna reflect its age and suggest that it was widespread during much of its history. The distributions of individual lineages indicate repeated spread of Oxyria digyna through North America over multiple glacial cycles. During the Last Glacial Maximum it persisted in multiple refugia in western North America, including Beringia, south of the continental ice, and within the northern limits of the Cordilleran ice sheet. Our data contribute to a growing body of evidence that arctic–alpine species have migrated from different source regions over multiple glacial cycles and that cryptic refugia contributed to persistence through the Last Glacial Maximum. PMID:22822441

  15. Late Pleistocene Rapid Climate Change Events Measured in Stalagmites From a Semi-Arid Cave in Iran Show Pan-Eurasian Climate Signal Matching NGRIP

    NASA Astrophysics Data System (ADS)

    Mehterian, S.; Pourmand, A.; Sharifi, A.; Murphy, L.; Lahijani, H. A. K.; Naderi, M.; Swart, P. K.

    2015-12-01

    Although new records of Pleistocene climate variability have begun to emerge from speleothems in Western and Eastern Asia, much remains unknown about climate variability on centennial to millennial timescales during the last glacial and interglacial periods across the interior of West Asia. The regional climate of West Asia is governed by interactions between the Northern Hemisphere Westerly Jet, the Siberian Anticyclone and the Indian Ocean Summer Monsoon, making this region highly sensitive to abrupt climate variability. Here we present the first high-resolution oxygen isotope record of two stalagmites from a cave in the semi-arid region of NW Iran. The records from Qaleh Kord Cave (QKC, 35°47'50"N, 48°51'25"E) span between 73 kya to 127 kya and cover marine isotope stages MIS4 and MIS5. The absolute chronology of both stalagmites was established using a novel high-precision U-Th geochronometry technique with multi-collection ICP-MS. The δ18O composition of QKC stalagmites closely agree with changes in δ18O composition of the NGRIP ice core from Greenland, indicating a close atmospheric teleconnection between the climate of the North Atlantic and the interior of West Asia during this period. Because the chronology of NGRIP beyond 60 kya is calculated via numerical flow models and not directly measured, data from our stalagmites provide absolute age tie points to improve the accuracy of the deepest portion of the ice record. Furthermore, agreement between our records and those from the Soreq (Israel) and Sanbao (China) caves in West and East Asia point to a pan-Eurasian climate signal. In order to investigate the mechanisms that drive changes in climate in Western Asia on millennial timescales and examine the role of orbital characteristics and changes in insolation on atmospheric circulation and precipitation during MIS5, we present results from fully-coupled general circulation simulation CESM1 at three time slices of 80, 95, and 115 kya.

  16. National Environmental Change Information System Case Study

    NASA Technical Reports Server (NTRS)

    Goodman, S. J.; Ritschard, R.; Estes, M. G., Jr.; Hatch, U.

    2001-01-01

    The Global Hydrology and Climate Center and NASA's Marshall Space Flight Center conducted a fact-finding case study for the Data Management Working Group (DMWG), now referred to as the Data and Information Working Group (DIWG), of the U.S. Global Change Research Program (USGCRP) to determine the feasibility of an interagency National Environmental Change Information System (NECIS). In order to better understand the data and information needs of policy and decision makers at the national, state, and local level, the DIWG asked the case study team to choose a regional water resources issue in the southeastern United States that had an impact on a diverse group of stakeholders. The southeastern United States was also of interest because the region experiences interannual climatic variations and impacts due to El Nino and La Nina. Jointly, with input from the DIWG, a focus on future water resources planning in the Apalachicola-Chattahoochee-Flint (ACF) River basins of Alabama, Georgia, and Florida was selected. A tristate compact and water allocation formula is currently being negotiated between the states and U.S. Army Corps of Engineers (COE) that will affect the availability of water among competing uses within the ACF River basin. All major reservoirs on the ACF are federally owned and operated by the U.S. Army COE. A similar two-state negotiation is ongoing that addresses the water allocations in the adjacent Alabama-Coosa-Tallapoosa (ACT) River basin, which extends from northwest Georgia to Mobile Bay. The ACF and ACT basins are the subject of a comprehensive river basin study involving many stakeholders. The key objectives of this case study were to identify specific data and information needs of key stakeholders in the ACF region, determine what capabilities are needed to provide the most practical response to these user requests, and to identify any limitations in the use of federal data and information. The NECIS case study followed the terms of reference

  17. Low order gravity field and sea-level: antarctic contribution to late-Pleistocen and Holocene volume changes

    NASA Technical Reports Server (NTRS)

    Ivins, Erik; Wu, Xioping; Gross, Richard

    2005-01-01

    We discuss the requirements of a GRACE follow-on mission, having the potential capability, for example, to monitor both cryospheric changes in Antarctica, Greenland and Patagonia and for capturing the associated solid earth creep responses that exist beneath these regions.

  18. Were Upper Pleistocene human/non-human predator occupations at the Témara caves (El Harhoura 2 and El Mnasra, Morocco) influenced by climate change?

    PubMed

    Campmas, Emilie; Michel, Patrick; Costamagno, Sandrine; Amani, Fethi; Stoetzel, Emmanuelle; Nespoulet, Roland; El Hajraoui, Mohamed Abdeljalil

    2015-01-01

    The influence of climate change on human settlements in coastal areas is a central question for archaeologists. This paper addresses this issue by focusing on the Témara region in Morocco. The study area was selected for two main reasons. First, it contains numerous caves with Upper Pleistocene deposits, which have yielded remains of anatomically modern humans in association with Aterian and Iberomaurusian artifacts. Second, these caves are currently located on the shore, thus this region is particularly sensitive to major climate change and sea level fluctuations. Diachronic taphonomic study of faunal remains from two sites in the region, El Harhoura 2 and El Mnasra caves, shows alternating human/non-human predator occupations. The lower layers of El Mnasra Cave dating to Oxygen Isotope Stage (OIS) 5 have yielded diverse ungulate remains with significant anthropogenic impact marks, together with numerous mollusk shells, Nassarius shell beads, hearths, lithics, some bone tools and used pigments. Faunal remains from the upper layers dating to OIS 4, 3 and 2 of El Harhoura 2 and El Mnasra caves, largely dominated by gazelles, provide evidence of carnivore activities, such as tooth marks, numerous semi-digested bones and coprolites alongside some anthropogenic signatures (cut marks and burnt bones). Non-human predators appear to be the main agents responsible for faunal modifications and accumulations. The 'non-intensive' nature of human occupation is confirmed by analyses of the lithic industry at El Harhoura 2. The 'intensive' human occupations date to OIS 5 and could have taken place during wet periods in connection with high sea levels, which allowed the exploitation of shellfish in this area. 'Non-intensive' human occupations generally correspond to arid periods and lower sea levels, during which the Témara area was further inland and may have been less attractive to humans.

  19. Geomorphological and sedimentary evidence for late Pleistocene to Holocene hydrological change along the Río Mamoré, Bolivian Amazon

    NASA Astrophysics Data System (ADS)

    Plotzki, A.; May, J.-H.; Preusser, F.; Veit, H.

    2013-11-01

    Aerial photography and satellite imagery reveal manifold geomorphological evidence of a dynamic evolution of past and present rivers in the Bolivian Amazon. Comparison of oxbow lake and meander scar dimensions along an inactive meander belt of the Río Mamoré (Llanos de Moxos, north-eastern Bolivia) and its modern counterpart suggests significant regional paleohydrological variability. We used these features as geomorphological and sedimentary archives to enhance our understanding of longer-term variations of the fluvial system. Late Pleistocene to Holocene hydrological changes of the Río Mamoré are inferred from: (i) the analysis of satellite imagery, (ii) discharge estimates from meander morphology, (iii) stratigraphic, and (iv) chronological information based on luminescence and radiocarbon dating. The combined data from three oxbows indicate that the now abandoned meander belt - the paleo-Mamoré - continued to be active at least until ∼5 ka, and likely even postdating 3 ka. An up to threefold increase in discharge is estimated for the modern Río Mamoré versus the paleo-Mamoré. The altered runoff regime may have triggered an avulsive shift towards the currently active Río Mamoré. The preceding increase in discharge in turn, was possibly related to a shift in climatic conditions, which changed markedly between the mid- and late Holocene in tropical South America. In addition, it may have been the indirect result of capturing the avulsive Río Grande system to the east of the Río Mamoré. Alternative explanations for the differences in dimensions of the paleo versus the modern Río Mamoré, i.e. contemporaneous activity of both rivers or alteration of site factors such as the channel/floodplain relationship, are considered to be unlikely.

  20. Environmental variation and population responses to global change.

    PubMed

    Lawson, Callum R; Vindenes, Yngvild; Bailey, Liam; van de Pol, Martijn

    2015-07-01

    Species' responses to environmental changes such as global warming are affected not only by trends in mean conditions, but also by natural and human-induced environmental fluctuations. Methods are needed to predict how such environmental variation affects ecological and evolutionary processes, in order to design effective strategies to conserve biodiversity under global change. Here, we review recent theoretical and empirical studies to assess: (1) how populations respond to changes in environmental variance, and (2) how environmental variance affects population responses to changes in mean conditions. Contrary to frequent claims, empirical studies show that increases in environmental variance can increase as well as decrease long-term population growth rates. Moreover, environmental variance can alter and even reverse the effects of changes in the mean environment, such that even if environmental variance remains constant, omitting it from population models compromises their ability to predict species' responses to changes in mean conditions. Drawing on theory relating these effects of environmental variance to the curvatures of population growth responses to the environment, we outline how species' traits such as phylogenetic history and body mass could be used to predict their responses to global change under future environmental variability.

  1. Pleistocene and Holocene Iberian flora: a complete picture and review

    NASA Astrophysics Data System (ADS)

    González Sampériz, Penélope

    2010-05-01

    A detailed analysis of the location and composition of Iberian vegetation types during the whole Pleistocene and Holocene periods shows a complex patched landscape with persistence of different types of ecosystems, even during glacial times. In addition, recent, high-resolution palaeoecological records are changing the traditional picture of post-glacial vegetation succession in the Iberian Peninsula. The main available charcoal and pollen sequences include, coniferous and deciduous forest, steppes, shrublands, savannahs and glacial refugia during the Pleistocene for Meso-thermophytes (phytodiversity reservoirs), in different proportions. This panorama suggests an environmental complexity that relates biotic responses to climate changes forced by Milankovitch cycles, suborbital forcings and by the latitudinal and physiographic particularities of the Iberian Peninsula. Thus, many factors are critical in the course of vegetational developments and strong regional differences are observed since the Early Pleistocene. Currently, the flora of Iberia is located in two biogeographical/climatic regions: the Eurosiberian and the Mediterranean. The first one includes northern and northwestern areas of the peninsula, where post-glacial responses of vegetation are very similar to Central Europe, although with some particularities due to its proximity to both the Atlantic Ocean and the Mediterranean region. The second one comprises the main territory of Iberia and shows more complex patterns and singularities, now and in the past. Steppe landscapes dominated extensive areas over all the territory during the cold spells of the Quaternary, especially during the Late Pleistocene up to the Last Glacial Maximum, but differences in composition of the dominant taxa (Compositae versus Artemisia) are observed since the Early Pleistocene, probably related to moisture regional gradients. Coastal shelves and intramountainous valleys, even in continental areas, are spots of floristic

  2. Environmental Education for Behaviour Change: Which Actions Should Be Targeted?

    ERIC Educational Resources Information Center

    Boyes, Edward; Stanisstreet, Martin

    2012-01-01

    One aim of environmental education is to enable people to make informed decisions about their environmental behaviour; this is particularly significant with environmental problems that are believed to be both major and imminent, such as climate change resulting from global warming. Previous research suggests no strong link between a person's…

  3. Planktic foraminifera shell chemistry response to seawater chemistry: Pliocene-Pleistocene seawater Mg/Ca, temperature and sea level change

    NASA Astrophysics Data System (ADS)

    Evans, David; Brierley, Chris; Raymo, Maureen E.; Erez, Jonathan; Müller, Wolfgang

    2016-03-01

    Foraminifera Mg/Ca paleothermometry forms the basis of a substantial portion of ocean temperature reconstruction over the last 5 Ma. Furthermore, coupled Mg/Ca-oxygen isotope (δ18O) measurements of benthic foraminifera can constrain eustatic sea level (ESL) independent of paleo-shoreline derived approaches. However, this technique suffers from uncertainty regarding the secular variation of the Mg/Ca seawater ratio (Mg/Casw) on timescales of millions of years. Here we present coupled seawater-test Mg/Ca-temperature laboratory calibrations of Globigerinoides ruber in order to test the widely held assumptions that (1) seawater-test Mg/Ca co-vary linearly, and (2) the Mg/Ca-temperature sensitivity remains constant with changing Mg/Casw. We find a nonlinear Mg/Catest-Mg/Casw relationship and a lowering of the Mg/Ca-temperature sensitivity at lower than modern Mg/Casw from 9.0% °C-1 at Mg/Casw = 5.2 mol mol-1 to 7.5 ± 0.9% °C-1 at 3.4 mol mol-1. Using our calibrations to more accurately calculate the offset between Mg/Ca and biomarker-derived paleotemperatures for four sites, we derive a Pliocene Mg/Casw ratio of ∼4.3 mol mol-1. This Mg/Casw implies Pliocene ocean temperature 0.9-1.9 °C higher than previously reported and, by extension, ESL ∼30 m lower compared to when one assumes that Pliocene Mg/Casw is the same as at present. Correcting existing benthic foraminifera datasets for Mg/Casw indicates that deep water source composition must have changed through time, therefore seawater oxygen isotope reconstructions relative to present day cannot be used to directly reconstruct Pliocene ESL.

  4. Landscape response to late Pleistocene climate change along the Puna Plateau margin: Sediment flux and cosmogenic landslide signatures modulated by basin geometry

    NASA Astrophysics Data System (ADS)

    Schildgen, T. F.; Robinson, R. A. J.; Savi, S.; Phillips, W. M.; Spencer, J. Q. G.; Bookhagen, B.; Scherler, D.; Tofelde, S.; Alonso, R. N.; Kubik, P.; Binnie, S. A.; Strecker, M. R.

    2015-12-01

    Along the steep flanks of the southern Central Andes (eastern margin of the Puna Plateau), fluvial fill terraces preserve archives of landscape response to climate change over millennial timescales. These archives record information about past erosion and aggradation rates, erosion processes, and even paleoclimate. In the Humahuaca Basin of NW Argentina, our 29 new optically stimulated luminescence ages of late Pleistocene fill terrace sediments demonstrate that past river aggradation occurred over different intervals on the west and east sides of the valley. On the west side, aggradation coincided with periods of increasing intensity of the South American Monsoon System and the South Atlantic Convergence Zone (increasing precipitation), while on the east side, aggradation coincided with periods of decreasing intensities of both systems (decreasing precipitation) or with more variable conditions. Denudation rates and grain-size dependencies from 70 new cosmogenic 10Be analyses reveal that landslides were more important during periods of increasing precipitation compared to today. On the west side of the valley, a sudden pulse of sediment led to aggradation near the intersection with the trunk stream. In contrast, on the east side, the pulse of sediment likely blocked the narrow bedrock gorges that characterize those catchments, leading to temporary sediment storage in upstream perched basins; sediment evacuation into the main valley occurred preferentially during periods of decreasing precipitation and fewer landslides. Different levels of fluvial connectivity to the trunk stream for the western and eastern catchments within the Humahuaca Basin produces heterogeneity in the locus of aggradation and the timing of sediment movement through the system. Hence, for larger basins that integrate sub-basins with differing geometries or degrees of connectivity, sedimentary responses to climate forcing are likely to be attenuated.

  5. Comprehension of climate change and environmental attitudes across the lifespan.

    PubMed

    Degen, C; Kettner, S E; Fischer, H; Lohse, J; Funke, J; Schwieren, C; Goeschl, T; Schröder, J

    2014-08-01

    Given the coincidence of the demographic change and climate change in the upcoming decades the aging voter gains increasing importance in climate change mitigation and adaptation processes. It is generally assumed that information status and comprehension of complex processes underlying climate change are prerequisites for adopting pro-environmental attitudes and taking pro-environmental actions. In a cross-sectional study, we investigated in how far (1) environmental knowledge and comprehension of feedback processes underlying climate change and (2) pro-environmental attitudes change as a function of age. Our sample consisted of 92 participants aged 25-75 years (mean age 49.4 years, SD 17.0). Age was negatively related to comprehension of system structures inherent to climate change, but positively associated with level of fear of consequences and anxiousness towards climate change. No significant relations were found between environmental knowledge and pro-environmental attitude. These results indicate that, albeit understanding of relevant structures of the climate system is less present in older age, age is not a limiting factor for being engaged in the complex dilemma of climate change. Results bear implications for the communication of climate change and pro-environmental actions in aging societies.

  6. Paleoecology: An Untapped Resource for Teaching Environmental Change

    ERIC Educational Resources Information Center

    Raper, Diana J.; Zander, Holli

    2009-01-01

    Global warming and climate change have become hot topics that incite debate, inspire scientific research, and influence international policy. However, the scientific research that provides the past climate and environmental information upon which contemporary environmental change is measured, receives little attention in high school curriculum.…

  7. Plio-Pleistocene Bering Sea - North Pacific Ocean Circulation Dynamics Inferred from Sediment Source Changes at the Meiji Drift, Northwest Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Vanlaningham, S.; Haley, B.; Hillier, S.; Alizai, A. H.

    2010-12-01

    The Pliocene is an interesting time in Earth’s history because it was warmer than today and could serve as an analog for how Earth might behave in response to future warming. It also precedes the onset of Northern Hemisphere glaciation that started ~3 million years ago. Yet it remains an open question whether closing of the Isthmus of Panama and opening of the Bering Strait impacted ocean circulation and climate 4-5 Ma. A large drift deposit in the northwest Pacific known as the Meiji Drift may hold clues about the possible impact of the Bering gateway on Pliocene climate dynamics in the Northern Hemisphere. It was previously demonstrated that the Meiji Drift is sensitive to changes at the Bering Strait, at least over the last 150 ka. This work investigates Plio-Pleistocene changes at the Meiji Drift using mineralogical and bulk sediment Nd isotopic techniques applied to the terrigenous fraction. Quantitative mineralogy of Meiji Drift sediment shows significant changes in quartz, plagioclase, K-feldspar, and amphibole at 5 Ma as well as around 1.5-2 Ma. Nd isotopic data show a transition from epsilon Nd values of +8 at 5 Ma to +1 by 3 Ma. These data suggest that circum-Pacific arc rocks were the dominant source of terrigenous sediment to the Meiji Drift around 5 Ma. From 5 to 3 Ma the sediment became progressively mixed with more continental-like source rocks. It is likely that increased flow from the Bering Sea (dominated by detritus from the Yukon River) to the North Pacific occurred ~5 Ma. This coincides with when the Bering Strait likely first opened with southward flow. But after the onset of Northern Hemisphere glaciation the sediment sources to the Meiji Drift likely began to oscillate at higher frequency with the opening and closing of the Bering gateway on glacial-interglacial timescales. Higher resolution work on the detrital fraction of the Meiji Drift will better constrain the timing, magnitude, and direction of ocean circulation changes in the Bering

  8. Color and Change, An Environmental Investigation.

    ERIC Educational Resources Information Center

    National Wildlife Federation, Washington, DC.

    This environmental unit is one of a series designed for integration within an existing curriculum. The unit is self-contained and requires very little teacher preparation. The philosophy of the series is based on an experience-oriented process that encourages students to work independently and at their own speeds. This particular unit is designed…

  9. World Wind Tools Reveal Environmental Change

    NASA Technical Reports Server (NTRS)

    2012-01-01

    Originally developed under NASA's Learning Technologies program as a tool to engage and inspire students, World Wind software was released under the NASA Open Source Agreement license. Honolulu, Hawaii based Intelesense Technologies is one of the companies currently making use of the technology for environmental, public health, and other monitoring applications for nonprofit organizations and Government agencies. The company saved about $1 million in development costs by using the NASA software.

  10. Record of middle Pleistocene climate change from Buck Lake, Cascade Range, southern Oregon - Evidence from sediment magnetism, trace-element geochemistry, and pollen

    USGS Publications Warehouse

    Rosenbaum, J.G.; Reynolds, R.L.; Adam, D.P.; Drexler, J.; Sarna-Wojcicki, A. M.; Whitney, G.C.

    1996-01-01

    Comparison of systematic variations in sediment magnetic properties to changes in pollen assemblages in middle Pleistocene lake sediments from Buck Lake indicates that the magnetic properties are sensitive to changes in climate. Buck Lake is located in southern Oregon just east of the crest of the Cascade Range. Lacustrine sediments, from 5.2 to 19.4 m in depth in core, contain tephra layers with ages of ???300-400 ka at 9.5 m and ???400-470 ka at 19.9 m. In these sediments magnetic properties reflect the absolute amount and relative abundances of detrital Fe-oxide minerals, titanomagnetite and hematite. The lacustrine section is divided into four zones on the basis of magnetic properties. Two zones (19.4-17.4 m and 14.5-10.3 m) of high magnetic susceptibility contain abundant Fe oxides and correspond closely to pollen zones that are indicative of cold, dry environments. Two low-susceptibility zones (17.4-14.5 m and 10.3-5.3 m) contain lesser amounts of Fe oxides and largely coincide with zones of warm-climate pollen. Transitions from cold to warm climate based on pollen are preceded by sharp changes in magnetic properties. This relation suggests that land-surface processes responded to these climate changes more rapidly than did changes in vegetation as indicated by pollen frequencies. Magnetic properties have been affected by three factors: (1) dissolution of Fe oxides, (2) variation in heavy-mineral content, and (3) variation in abundance of fresh volcanic rock fragments. Trace-element geochemistry, employing Fe and the immobile elements Ti and Zr, is utilized to detect postdepositional dissolution of magnetic minerals that has affected the magnitude of magnetic properties with little effect on the pattern of magnetic-property variation. Comparison of Ti and Zr values, proxies for heavy-mineral content, to magnetic properties demonstrates that part of the variation in the amount of magnetite and nearly all of the variation in the amount of hematite are due to

  11. Rapid anthropogenic response to short-term aeolian-fluvial palaeoenvironmental changes during the Late Pleistocene-Holocene transition in the northern Negev Desert, Israel

    NASA Astrophysics Data System (ADS)

    Roskin, Joel; Katra, Itzhak; Agha, Nuha; Goring-Morris, A. Nigel; Porat, Naomi; Barzilai, Omry

    2014-09-01

    Archaeological investigations along Nahal Sekher on the eastern edge of Israel's northwestern Negev Desert dunefield revealed concentrations of Epipalaeolithic campsites associated respectively with ancient water bodies. This study, aimed at better understanding the connections between these camps and the water bodies, is concerned with a cluster of Natufian sites. A comprehensive geomorphological study integrating field mapping, stratigraphic sections, sedimentological analysis and optically stimulated luminescence (OSL) ages was conducted in the vicinity of a recently excavated Natufian campsite of Nahal Sekher VI whose artifacts directly overlay aeolian sand dated by OSL to 12.4 ± 0.7 and 11.7 ± 0.5 ka. Residual sequences of diagnostic silty sediments, defined here as low-energy fluvial fine-grained deposits (LFFDs), were identified within the drainage system of central Nahal Sekher around the Nahal Sekher VI site. LFFD sections were found to represent both shoreline and mid-water deposits. The thicker mid-water LFFD deposits (15.7 ± 0.7-10.7 ± 0.5 ka) date within the range of the Epipalaeolithic campsites, while the upper and shoreline LFFD units that thin out into the sands adjacent to the Nahal Sekher VI site display slightly younger ages (10.8 ± 0.4 ka-7.6 ± 0.4 ka). LFFD sedimentation by low-energy concentrated flow and standing-water developed as a result of proximal downstream dune-damming. These water bodies developed as a result of encroaching sand that initially crossed central Nahal Sekher by 15.7 ± 0.7 ka and probably intermittently blocked the course of the wadi. LFFD deposition was therefore a response to a unique combination of regional sand supply due to frequent powerful winds and does not represent climate change in the form of increased precipitation or temperature change. The chronostratigraphies affiliate the Natufian sites to the adjacent ancient water bodies. These relations reflect a rapid, but temporary anthropogenic response to a

  12. Time spans of soil formation and late Pleistocene-Holocene climate changes in the Somma-Vesuvius volcano area, southern Italy

    NASA Astrophysics Data System (ADS)

    Scarciglia, Fabio; Zumpano, Veronica; Sulpizio, Roberto; Terribile, Fabio; Pulice, Iolanda; La Russa, Mauro F.

    2013-04-01

    Time spans of soil formation and climate changes occurred during the late Pleistocene to the middle Holocene are investigated in a pedostratigraphic succession located in the piedmont of the Somma-Vesuvius volcano (Campania region, southern Italy) using a multidisciplinary approach. We focused on five well-known and well-dated primary tephra and four interlayered volcanic soils developed on and/or buried by them. The pyroclastic layers give detailed chronological constraints to the stratigraphy. From bottom to top the following tephra were identified in the field: Pomici di Base (22 ka BP), Pomici Verdoline (19 ka BP), Agnano Pomici Principali (12.26 ka BP), Mercato (8.9 ka BP) and Avellino (3.9 ka BP), all of them representing volcanic products of explosive eruptions of the Somma-Vesuvius, except the third one, sourced from the westerly Phlegrean Fields. The four pedons were characterized in terms of morphological, physical, chemical, mineralogical and micromorphological features. Special attention was given to reconstruct the main soil-forming processes, paleoenvironmental and paleoclimatic conditions, degree of soil development and associated time ranges. Moreover, further tephra were identified in the field within some of above pedons. One of them was easily recognized and referred to the Agnano Monte Spina eruption (4.2-4.3 ka BP, Phlegrean Fields provenance), whereas the others were not previously known in the Somma-Vesuvius stratigraphy. On the basis of SEM-EDS analyses (chemical composition and morphoscopic observations), coupled with their stratigraphic position and literature compositional databases, they were related to the Soccavo 4-5 and the Tufi Biancastri eruptions from the Phlegrean Fields. This interpretation permitted to fix further age constrains for more detailed assessment of rates of soil formation and climatic interpretation. Major late Quaternary climatic phases are suggested by changes in the extent of development of andic properties, iron

  13. Environmental change explains cichlid adaptive radiation at Lake Malawi over the past 1.2 million years.

    PubMed

    Ivory, Sarah J; Blome, Margaret W; King, John W; McGlue, Michael M; Cole, Julia E; Cohen, Andrew S

    2016-10-18

    Long paleoecological records are critical for understanding evolutionary responses to environmental forcing and unparalleled tools for elucidating the mechanisms that lead to the development of regions of high biodiversity. We use a 1.2-My record from Lake Malawi, a textbook example of biological diversification, to document how climate and tectonics have driven ecosystem and evolutionary dynamics. Before ∼800 ka, Lake Malawi was much shallower than today, with higher frequency but much lower amplitude water-level and oxygenation changes. Since ∼800 ka, the lake has experienced much larger environmental fluctuations, best explained by a punctuated, tectonically driven rise in its outlet location and level. Following the reorganization of the basin, a change in the pacing of hydroclimate variability associated with the Mid-Pleistocene Transition resulted in hydrologic change dominated by precession rather than the high-latitude teleconnections recorded elsewhere. During this time, extended, deep lake phases have abruptly alternated with times of extreme aridity and ecosystem variability. Repeated crossings of hydroclimatic thresholds within the lake system were critical for establishing the rhythm of diversification, hybridization, and extinction that dominate the modern system. The chronology of these changes closely matches both the timing and pattern of phylogenetic history inferred independently for the lake's extraordinary array of cichlid fish species, suggesting a direct link between environmental and evolutionary dynamics.

  14. Late Quaternary environmental change in the Bonneville basin, western USA

    USGS Publications Warehouse

    Madsen, D.B.; Rhode, D.; Grayson, D.K.; Broughton, J.M.; Livingston, S.D.; Hunt, J.; Quade, Jay; Schmitt, D.N.; Shaver, M. W.

    2001-01-01

    Excavation and analyses of small animal remains from stratified raptor deposits spanning the last 11.5 ka, together with collection and analysis of over 60 dated fossil woodrat midden samples spanning the last 50 ka, provide a detailed record of changing climate in the eastern Great Basin during the late Pleistocene and Holocene. Sagebrush steppe dominated the northern Bonneville basin during the Full Glacial, suggesting that conditions were cold and relatively dry, in contrast to the southern basin, which was also cold but moister. Limber pine woodlands dominated ???13-11.5 ka, indicating increased dryness and summer temperatures ???6-7??C cooler than present. This drying trend accelerated after ???11.5 ka causing Lake Bonneville to drop rapidly, eliminating 11 species of fish from the lake. From ???11.5-8.2 ka xerophytic sagebrush and shadscale scrub replaced more mesophilic shrubs in a step-wise fashion. A variety of small mammals and plants indicate the early Holocene was ???3??C cooler and moister than at present, not warmer as suggested by a number of climatic models. The diversity of plants and animals changed dramatically after 8.2 ka as many species disappeared from the record. Some of the upland species returned after ???4 ka and Great Salt Lake became fresh enough at ???3.4 and ???1.2 ka to support populations of Utah chub. ?? 2001 Elsevier Science B.V.

  15. Marine environmental changes at the Brazilian equatorial margin related to Amazon River evolution during the Neogene

    NASA Astrophysics Data System (ADS)

    Lammertsma, Emmy; Troelstra, Simon; Sangiorgi, Francesca; Chemale, Farid, Jr.; do Carmo, Dermeval A.; D'Avila, Roberto; Soares, Emilson; Hoorn, Carina

    2014-05-01

    Today, the nutrient-rich Amazon River outflow causes massive algal blooms in the western equatorial Atlantic Ocean, forming a considerable carbon sink as well as a primary food source in the otherwise oligotrophic surface water. However, the history of this high-productivity system is largely unknown, although a strong relation to the evolution of the Amazon River can be expected. The Amazon submarine fan provides direct evidence for the development of a transcontinental river system, of which the base of the primarily Andean-sourced siliciclastic deposits is dated as late Miocene. Ditch cuttings from Amazon Fan exploration 'Well 2' were made available by Petrobras for microfossil and lithological research. 'Well 2' is located on the uppermost fan at a water depth of 750 meters. Organic-walled dinoflagellate cyst and foraminifer assemblages were studied to reconstruct Neogene marine environmental changes in relation to the Amazon River development. Planktonic foraminifera are present throughout the studied section and largely confirm the already available biostratigraphic age determination based on nannofossils. Benthic foraminifer assemblages indicate that the paleo-water depth has not substantially deviated from current conditions. The ecological affinities of most observed dinocyst taxa are well known, which allows us to reconstruct changes in paleo-productivity based on the assemblages. Mineral composition suggests that local river systems already drained into the Amazon basin before the onset of the transcontinental system, but environmental conditions remained oligotrophic at this time. Decreased abundances of both dinocysts and planktonic foraminifera during the Pleistocene are related to highest sedimentation rates (dilution effect). Overall, a complex interplay of orogenesis, climatic and sea level variations during the Neogene are responsible for the fluvially-induced changes in the marine environment at the Atlantic margin.

  16. Fluvial system response to late Pleistocene-Holocene sea-level change on Santa Rosa Island, Channel Islands National Park, California

    USGS Publications Warehouse

    Schumann, R. Randall; Pigati, Jeffery S.; McGeehin, John P.

    2016-01-01

    Santa Rosa Island (SRI) is one of four east-west aligned islands forming the northern Channel Islands chain, and one of the five islands in Channel Islands National Park, California, USA. The island setting provides an unparalleled environment in which to record the response of fluvial systems to major changes of sea level. Many of the larger streams on the island occupy broad valleys that have been filled with alluvium and later incised to form steep- to vertical-walled arroyos, leaving a relict floodplain as much as 12–14 m above the present channel. The period of falling sea level between the end of the last interglacial highstand at ~ 80 ka and the last glacial lowstand at ~ 21 ka was marked by erosion and incision in the uplands and by deposition of alluvial sediment on the exposed marine shelf. Sea level rose relatively rapidly following the last glacial lowstand of − 106 m, triggering a shift from an erosional to a depositional sedimentary regime. Accumulation of sediment occurred first through vertical and lateral accretion in broad, shallow channels on the shelf. Channel avulsion and delta sedimentation produced widespread deposition, creating lobes or wedges of sediment distributed across relatively large areas of the shelf during the latest Pleistocene. Backfilling of valleys onshore (landward of present sea level) appears to have progressed in a more orderly and predictable fashion throughout the Holocene primarily because the streams were confined to their valleys. Vertical aggradation locally reduced stream gradients, causing frequent overbank flooding and lateral channel shift by meandering and/or avulsion. Local channel gradient and morphology, short-term climate variations, and intrinsic controls also affected the timing and magnitudes of these cut, fill, and flood events, and are reflected in the thickness and spacing of the episodic alluvial sequences. Floodplain aggradation within the valleys continued until at least 500 years ago

  17. Fluvial system response to late Pleistocene-Holocene sea-level change on Santa Rosa Island, Channel Islands National Park, California

    NASA Astrophysics Data System (ADS)

    Schumann, R. Randall; Pigati, Jeffrey S.; McGeehin, John P.

    2016-09-01

    Santa Rosa Island (SRI) is one of four east-west aligned islands forming the northern Channel Islands chain, and one of the five islands in Channel Islands National Park, California, USA. The island setting provides an unparalleled environment in which to record the response of fluvial systems to major changes of sea level. Many of the larger streams on the island occupy broad valleys that have been filled with alluvium and later incised to form steep- to vertical-walled arroyos, leaving a relict floodplain as much as 12-14 m above the present channel. The period of falling sea level between the end of the last interglacial highstand at ~ 80 ka and the last glacial lowstand at ~ 21 ka was marked by erosion and incision in the uplands and by deposition of alluvial sediment on the exposed marine shelf. Sea level rose relatively rapidly following the last glacial lowstand of - 106 m, triggering a shift from an erosional to a depositional sedimentary regime. Accumulation of sediment occurred first through vertical and lateral accretion in broad, shallow channels on the shelf. Channel avulsion and delta sedimentation produced widespread deposition, creating lobes or wedges of sediment distributed across relatively large areas of the shelf during the latest Pleistocene. Backfilling of valleys onshore (landward of present sea level) appears to have progressed in a more orderly and predictable fashion throughout the Holocene primarily because the streams were confined to their valleys. Vertical aggradation locally reduced stream gradients, causing frequent overbank flooding and lateral channel shift by meandering and/or avulsion. Local channel gradient and morphology, short-term climate variations, and intrinsic controls also affected the timing and magnitudes of these cut, fill, and flood events, and are reflected in the thickness and spacing of the episodic alluvial sequences. Floodplain aggradation within the valleys continued until at least 500 years ago, followed by

  18. Determining molecular responses to environmental change in soybeans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As the global climate changes, plants will be challenged by environmental stresses that are more extreme and more frequent. The average yield loss due to environmental stresses is currently estimated to be more than 50% for major crop species and is the major limitation to world food production. The...

  19. Late Pleistocene and Holocene mammal extinctions on continental Africa

    NASA Astrophysics Data System (ADS)

    Faith, J. Tyler

    2014-01-01

    Understanding the cause of late Quaternary mammal extinctions is the subject of intense debate spanning the fields of archeology and paleontology. In the global context, the losses on continental Africa have received little attention and are poorly understood. This study aims to inspire new discussion of African extinctions through a review of the extinct species and the chronology and possible causes of those extinctions. There are at least 24 large mammal (> 5 kg) species known to have disappeared from continental Africa during the late Pleistocene or Holocene, indicating a much greater taxonomic breadth than previously recognized. Among the better sampled taxa, these losses are restricted to the terminal Pleistocene and early Holocene, between 13,000 and 6000 yrs ago. The African extinctions preferentially affected species that are grazers or prefer grasslands. Where good terrestrial paleoenvironmental records are present, extinctions are associated with changes in the availability, productivity, or structure of grassland habitats, suggesting that environmental changes played a decisive role in the losses. In the broader evolutionary context, these extinctions represent recent examples of selective taxonomic winnowing characterized by the loss of grassland specialists and the establishment of large mammal communities composed of more ecologically flexible taxa over the last million years. There is little reason to believe that humans played an important role in African extinctions.

  20. Pliocene-Pleistocene changes in Arctic sea-ice cover: New biomarker records from Fram Strait/Yermak Plateau (ODP Sites 911 and 912)

    NASA Astrophysics Data System (ADS)

    Stein, Ruediger; Fahl, Kirsten

    2013-04-01

    Recently, a novel and promising biomarker proxy for reconstruction of Arctic sea-ice conditions was developed and is based on the determination of a highly branched isoprenoid with 25 carbons (IP25; Belt et al., 2007). Following this pioneer IP25 study by Belt and colleagues, several IP25 studies of marine surface sediments and sediment cores as well as sediment trap samples from northpolar areas were carried out successfully and allowed detailed reconstruction of modern and late Quaternary sea ice variability in these regions (e.g., Massé et al., 2008; Müller et al., 2009, 2011; Vare et al., 2009; Belt et al., 2010; Fahl and Stein, 2012; for review see Stein et al., 2012). Here, we present new (low-resolution) biomarker records from Ocean Drilling Program (ODP) Sites 911 and 912, representing the Pliocene-Pleistocene time interval (including the interval of major intensification of Northern Hemisphere Glaciation near 2.7 Ma). These data indicate that sea ice of variable extent was present in the Fram Strait/southern Yermak Plateau area during most of the time period under investigation. In general, an increase in sea-ice cover seems to correlate with phases of extended late Pliocene-Pleistocene continental ice-sheets. At ODP Site 912, a significant increase in sea-ice extension occurred near 1.2 Ma (Stein and Fahl, 2012). Furthermore, our data support the idea that a combination of IP25 and open water, phytoplankton biomarker data ("PIP25 index"; Müller et al., 2011) may give more reliable and quantitative estimates of past sea-ice cover (at least for the study area). This study reveals that the novel IP25/PIP25 biomarker approach has potential for semi-quantitative paleo-sea ice studies covering the entire Quaternary and motivate to carry out further detailed high-resolution research on ODP/IODP material using this proxy. References Belt, S.T., Massé, G., Rowland, S.J., Poulin, M., Michel, C., LeBlanc, B., 2007. A novel chemical fossil of palaeo sea ice: IP25

  1. Cellular modes of adaptation to environmental changes

    NASA Astrophysics Data System (ADS)

    Huckle, William R.

    2001-10-01

    Eukaryotic cells are remarkably adaptable entities. Whether embedded in solid tissues or freely suspended in blood or other fluids, cells principally exist in an aqueous environment but maintain a hydrophobic barrier, the plasma membrane, across which changes in the environment are detected. Utilizing specialized macromolecular components, cells can sense changes in temperature, hydrostatic pressure, oxygen tension, shear, shape, osmolarity, pH, electrical potential, electromagnetic radiation, and the concentrations of specific chemical compounds. Modes of response are equally varied, ranging from rapid secretion of stored substances to irreversible functional differentiation to self-destruction. Recent research has elucidated many of the enzymatic and genetic programs that accomplish these adaptations and suggests novel targets for therapeutic intervention.

  2. Assessing stream temperature response to environmental change

    NASA Astrophysics Data System (ADS)

    MacDonald, R. J.; Boon, S.; Byrne, J. M.

    2010-12-01

    Stream temperature controls aquatic ecosystem function by directly influencing water quality, ecosystem productivity, and the physiological functioning of aquatic organisms. To date, there are limited studies of the impacts of environmental disturbance on stream temperature, particularly on the eastern slopes of the Rocky Mountains. This region provides key habitat for native salmonid species such as westslope cutthroat trout (Oncorhynchus clarkii lewisi) and bull trout (Salvelinus confluentus), which are listed as ‘threatened’ and ‘species of special concern’, respectively. Increases in stream temperature could limit habitat availability, reduce competitive advantage, and potentially increase mortality rates for these native species. This study uses field data collected at high spatiotemporal resolution to develop a spatial stream temperature model that simulates the mass and energy balance of the stream system. Preliminary field results demonstrate the high spatial and temporal variability in processes governing stream temperature in three study stream reaches. Groundwater/surface water interactions, topographic setting, and local meteorological conditions all contribute in determining stream thermal regimes. This work discusses how these primary drivers of stream temperature can be incorporated into a physically based spatial model, and demonstrates how depending on the scale of interest, the temperature of a stream can be governed by very different contributing factors.

  3. Environmental and policy change to support healthy aging.

    PubMed

    Hunter, Rebecca H; Sykes, Kathy; Lowman, Sarah G; Duncan, Richard; Satariano, William A; Belza, Basia

    2011-10-01

    Given the growing evidence of the influence of the environment on older adult health, the need to design and implement effective environmental policy around healthy and vital aging is urgent. This article describes issues amenable to improvement through policy change, evidence supporting specific policy approaches and outcomes, and promising strategies for implementing those approaches. Key areas of focus are neighborhood design and safety, housing, transportation, and mobility. Strategies to build capacity for policy change are also addressed. Our goals are to foster greater attention to environmental change in support of healthy aging and to illuminate directions for policy change.

  4. Holocene environmental change and vegetation contraction in the Sonoran Desert

    NASA Astrophysics Data System (ADS)

    McAuliffe, Joseph R.; McDonald, Eric V.

    2006-03-01

    Two types of microtopographic features ( plant scar mounds and plant scar depressions) on surfaces of barren desert pavements provide a unique record of the former presence of large perennial plants. Evidence of bioturbation by burrowing animals extends more than 1 m beneath each type of plant scar, indicating that both features originated as large bioturbation mounds. Formation of bioturbation mounds in desertscrub environments is generally restricted to areas beneath widely separated, large perennial plants. The contrasting forms of plant scars (mounds vs. depressions) represent time-dependent changes following disappearance of the large plants and eventual cessation of bioturbation. Plant scar mounds represent a geologically recent episode of plant mortality, whereas plant scar depressions represent the disappearance of plants at a considerably earlier time, possibly at the Pleistocene-Holocene transition. Contrasting spatial distributions of the two kinds of plant scars indicate that vegetation on alluvial fans has progressively contracted from a more diffuse, former vegetation cover, yielding the wide, barren pavement surfaces present today. In less arid portions of the Sonoran Desert, spatial distribution of recent plant mortality due to persistent, severe drought provides an analog of the progressive loss of plants from different parts of the landscape in the past.

  5. Environmentally induced heritable changes in flax.

    PubMed

    Johnson, Cory; Moss, Tiffanie; Cullis, Christopher

    2011-01-26

    Some flax varieties respond to nutrient stress by modifying their genome and these modifications can be inherited through many generations. Also associated with these genomic changes are heritable phenotypic variations. The flax variety Stormont Cirrus (Pl) when grown under three different nutrient conditions can either remain inducible (under the control conditions), or become stably modified to either the large or small genotroph by growth under high or low nutrient conditions respectively. The lines resulting from the initial growth under each of these conditions appear to grow better when grown under the same conditions in subsequent generations, notably the Pl line grows best under the control treatment indicating that the plants growing under both the high and low nutrients are under stress. One of the genomic changes that are associated with the induction of heritable changes is the appearance of an insertion element (LIS-1) while the plants are growing under the nutrient stress. With respect to this insertion event, the flax variety Stormont Cirrus (Pl) when grown under three different nutrient conditions can either remain unchanged (under the control conditions), have the insertion appear in all the plants (under low nutrients) and have this transmitted to the next generation, or have the insertion (or parts of it) appear but not be transmitted through generations (under high nutrients). The frequency of the appearance of this insertion indicates that it is under positive selection, which is also consistent with the growth response in subsequent generations. Leaves or meristems harvested at various stages of growth are used for DNA and RNA isolation. The RNA is used to identify variation in expression associated with the various growth environments and/or t he presence/absence of LIS-1. The isolated DNA is used to identify those plants in which the insertion has occurred.

  6. The aftermath of megafaunal extinction: ecosystem transformation in Pleistocene Australia.

    PubMed

    Rule, Susan; Brook, Barry W; Haberle, Simon G; Turney, Chris S M; Kershaw, A Peter; Johnson, Christopher N

    2012-03-23

    Giant vertebrates dominated many Pleistocene ecosystems. Many were herbivores, and their sudden extinction in prehistory could have had large ecological impacts. We used a high-resolution 130,000-year environmental record to help resolve the cause and reconstruct the ecological consequences of extinction of Australia's megafauna. Our results suggest that human arrival rather than climate caused megafaunal extinction, which then triggered replacement of mixed rainforest by sclerophyll vegetation through a combination of direct effects on vegetation of relaxed herbivore pressure and increased fire in the landscape. This ecosystem shift was as large as any effect of climate change over the last glacial cycle, and indicates the magnitude of changes that may have followed megafaunal extinction elsewhere in the world.

  7. Deformed cross-stratified deposits in the Early Pleistocene tidally-dominated Catanzaro strait-fill succession, Calabrian Arc (Southern Italy): Triggering mechanisms and environmental significance

    NASA Astrophysics Data System (ADS)

    Chiarella, Domenico; Moretti, Massimo; Longhitano, Sergio G.; Muto, Francesco

    2016-10-01

    The Early-Pleistocene Catanzaro strait-fill succession consists of large-scale tidal sets, accumulated in a tectonically confined basin during a phase of rapid relative sea-level rise. It crops out mainly in the present-day Catanzaro Trough where numerous field sections supported the characterization of the vertical and lateral facies variations and the documentation of a variety of soft-sediment deformation structures, exposed throughout their vertical and lateral extents. The soft-sediment deformation structures (SSDS) are the result of liquefaction and fluidization processes that deformed cross-laminations and other primary structures into folds, fluid-escape structures, and structureless expanses. Three different groups of SSDS have been documented in the cross-stratified deposits of the Catanzaro strait. The detailed description of these soft-sediment deformation structures in a depositional context established by facies analysis enables interpretation in terms of possible trigger mechanisms. Consistent relationships between the occurrence of distinctive SSDS and specific tidally dominated facies have been established, indicating a probable autogenic origin for the soft-sediment deformations. Liquefaction and fluidization features are interpreted as the result of increases in water pore-pressure, induced by overloading. In particular, two types of overloading agents are hypothesized, which affect the lee and stoss sides of the migrating dunes in distinct events, and inducing the deformation of foreset laminae or sets of cross-strata, respectively.

  8. Reintroducing Environmental Change Drivers in Biodiversity-Ecosystem Functioning Research.

    PubMed

    De Laender, Frederik; Rohr, Jason R; Ashauer, Roman; Baird, Donald J; Berger, Uta; Eisenhauer, Nico; Grimm, Volker; Hommen, Udo; Maltby, Lorraine; Meliàn, Carlos J; Pomati, Francesco; Roessink, Ivo; Radchuk, Viktoriia; Van den Brink, Paul J

    2016-12-01

    For the past 20 years, research on biodiversity and ecosystem functioning (B-EF) has only implicitly considered the underlying role of environmental change. We illustrate that explicitly reintroducing environmental change drivers in B-EF research is needed to predict the functioning of ecosystems facing changes in biodiversity. Next we show how this reintroduction improves experimental control over community composition and structure, which helps to provide mechanistic insight on how multiple aspects of biodiversity relate to function and how biodiversity and function relate in food webs. We also highlight challenges for the proposed reintroduction and suggest analyses and experiments to better understand how random biodiversity changes, as studied by classic approaches in B-EF research, contribute to the shifts in function that follow environmental change.

  9. Plant ecology. Anthropogenic environmental changes affect ecosystem stability via biodiversity.

    PubMed

    Hautier, Yann; Tilman, David; Isbell, Forest; Seabloom, Eric W; Borer, Elizabeth T; Reich, Peter B

    2015-04-17

    Human-driven environmental changes may simultaneously affect the biodiversity, productivity, and stability of Earth's ecosystems, but there is no consensus on the causal relationships linking these variables. Data from 12 multiyear experiments that manipulate important anthropogenic drivers, including plant diversity, nitrogen, carbon dioxide, fire, herbivory, and water, show that each driver influences ecosystem productivity. However, the stability of ecosystem productivity is only changed by those drivers that alter biodiversity, with a given decrease in plant species numbers leading to a quantitatively similar decrease in ecosystem stability regardless of which driver caused the biodiversity loss. These results suggest that changes in biodiversity caused by drivers of environmental change may be a major factor determining how global environmental changes affect ecosystem stability.

  10. Scytonemin and Photosynthetic Pigment Proxies for Late Pleistocene/Holocene Environmental Change in the Eastern Great Basin

    NASA Astrophysics Data System (ADS)

    Fulton, J. M.; Van Mooy, B. A. S.

    2015-12-01

    Sedimentary pigments are biomarkers of photosynthetic organisms, most commonly derived from aquatic bacteria and algae but also with potential terrigenous sources. We detected a diverse pigment assemblage with variable down-core distributions in Great Salt Lake (GSL) sediments deposited since ca. 280 ka (GLAD1-GSL00, core 4). The most abundant pigments included derivatives of chlorophyll a, most likely from algae or cyanobacteria, bacteriochlorophyll c from green sulfur bacteria, okenone from purple sulfur bacteria, and scytonemin from UV-exposed cyanobacteria. Scytonemin is a biomarker for colonial cyanobacteria exposed to UV-radiation. In GSL it has potential sources from bioherms on the shoreline or microbiotic soil crusts from the adjacent Great Basin Desert. Scytonemin concentration was highest in the Upper Salt and Sapropel (USS) unit, deposited between 11.5-10 ka in shallow water (ca. 10 m), following deep pluvial Lake Bonneville (30-18 cal ka), the Provo lake level (ca. 18-15 cal ka), and the Gilbert transgression (11.6 cal ka). Scytonemin concentration was very low in sediments deposited during the deep lake phases, even though bioherms were prominent shoreline features. The USS was deposited under hypersaline waters and contained remarkably low concentrations of photosynthetic pigment derivatives that would be expected in organic-matter-rich sediments deposited under productive surface waters or anoxic bottom waters. Stable carbon and nitrogen isotopic data point toward a desert soil crust source for scytonemin in the USS, similar to what we previously observed in the Holocene Black Sea sapropel. We propose that increased aridity supported the widespread occurrence and erosion of microbiotic soil crusts during deposition of the USS. This is consistent with interpretations of Great Salt Lake hydrology, pointing toward a broader regional aridity event. Holocene sediments above the USS also contain scytonemin at relatively high concentration, consistent with persistent arid/semi-arid conditions.

  11. Environmental Change and Out-Migration: Evidence from Nepal

    PubMed Central

    Massey, Douglas S.; Axinn, William G.; Ghimire, Dirgha J.

    2011-01-01

    Scholars and activists have hypothesized a connection between environmental change and out-migration. In this paper we test this hypothesis using data from Nepal. We operationalize environmental change in terms of declining land cover, rising times required to gather organic inputs, increasing population density, and perceived declines in agricultural productivity. In general, environmental change is more strongly related to short- than long-distance moves. Holding constant the effects of other social and economic variables, we find that local moves are predicted by perceived declines in productivity, declining land cover, and increasing time required to gather firewood. Long-distance moves are predicted by perceived declines in productivity, but the effect is weaker than in the model of short-distance mobility. We also show that effects of environmental change vary by gender and ethnicity, with women being more affected by changes in the time required to gather fodder and men by changes in the time to gather firewood, and high caste Hindus generally being less affect than others by environmental change. PMID:21350676

  12. Linking degradation status with ecosystem vulnerability to environmental change

    USGS Publications Warehouse

    Angeler, David G.; Baho, Didier L.; Allen, Craig R.; Johnson, Richard K.

    2015-01-01

    Environmental change can cause regime shifts in ecosystems, potentially threatening ecosystem services. It is unclear if the degradation status of ecosystems correlates with their vulnerability to environmental change, and thus the risk of future regime shifts. We assessed resilience in acidified (degraded) and circumneutral (undegraded) lakes with long-term data (1988–2012), using time series modeling. We identified temporal frequencies in invertebrate assemblages, which identifies groups of species whose population dynamics vary at particular temporal scales. We also assessed species with stochastic dynamics, those whose population dynamics vary irregularly and unpredictably over time. We determined the distribution of functional feeding groups of invertebrates within and across the temporal scales identified, and in those species with stochastic dynamics, and assessed attributes hypothesized to contribute to resilience. Three patterns of temporal dynamics, consistent across study lakes, were identified in the invertebrates. The first pattern was one of monotonic change associated with changing abiotic lake conditions. The second and third patterns appeared unrelated to the environmental changes we monitored. Acidified and the circumneutral lakes shared similar levels and patterns of functional richness, evenness, diversity, and redundancy for species within and across the observed temporal scales and for stochastic species groups. These similar resilience characteristics suggest that both lake types did not differ in vulnerability to the environmental changes observed here. Although both lake types appeared equally vulnerable in this study, our approach demonstrates how assessing systemic vulnerability by quantifying ecological resilience can help address uncertainty in predicting ecosystem responses to environmental change across ecosystems.

  13. Late Pleistocene evolution of the Rhine-Meuse system in the southern North Sea basin: imprints of climate change, sea-level oscillation and glacio-isostacy

    NASA Astrophysics Data System (ADS)

    Busschers, F. S.; Kasse, C.; van Balen, R. T.; Vandenberghe, J.; Cohen, K. M.; Weerts, H. J. T.; Wallinga, J.; Johns, C.; Cleveringa, P.; Bunnik, F. P. M.

    2007-12-01

    High-resolution continuous core material, geophysical measurements, and hundreds of archived core descriptions enabled to identify 13 Late Pleistocene Rhine-Meuse sedimentary units in the infill of the southern part of the North Sea basin (the Netherlands, northwestern Europe). This sediment record and a large set of Optical Stimulated Luminescence dates, 14C dates and biostratigraphical data, allowed to establish detailed relationships between climate change, sea-level oscillation, glaciation history and the sedimentary development of the Rhine fluvial system during the last glacial cycle (Marine Isotope Stages 5e-2, Eemian-Weichselian). A well-preserved Eemian sediment record was encountered as the infill of a Late Saalian (MIS6) subglacial basin. Part of this record reflects groundwater rise controlled (fine-grained) sedimentation as a result of postglacial (early) Eemian sea-level rise. It shows strong analogy to developments known from the Holocene Rhine-Meuse delta. Outside of the glacial depressions near coastal deposits are only fragmentarily preserved. The Early Glacial Rhine sediment record is dominated by organic debris and peat layers, marking landscape stability and low fluvial activity. Part of this record may have been formed under near coastal conditions. Significant amounts of reworked marine biomarkers in the lag-deposits of Early Pleniglacial (MIS4) fluvial systems indicate that this period is characterized by extensive reworking of older (MIS5) near-coastal sediments. Despite the marked Early Pleniglacial climatic cooling, input of new sediment from the drainage basin was relatively low, a feature that is related to the presence of regolith protective relic soil complexes in the basin. During the early Middle Pleniglacial, a major Rhine avulsion indicates the system was in an aggrading mode and that sediment supply into the lower reaches of the Rhine had strongly increased. This increase in sediment supply coincided with the timing of major

  14. Investigation of environmental change pattern in Japan

    NASA Technical Reports Server (NTRS)

    Maruyasu, T. (Principal Investigator)

    1977-01-01

    The author has identified the following significant results. In the Plains of Tokachi, where the scale of agricultural field was comparatively large in Japan, LANDSAT data with its accuracy have proved to be useful enough to observe the actual condition of agricultural land use and changes more accurately than present methods. Species and ages of grasses in pasture were identified and soils were classified into several types. The actual land cover and ecological environment were remarkably changeable at the rapidly industrialized area by the urbanization in the flat plane and also by the forest works and road construction in the mountainous area. The practical use of the recognition results was proved as the base map of the field survey or the retouching work of the vegetation and land use. There was a 10% cut in cost, labor, and time. Vegetation cover in Tokyo districts was estimated by both the multiregression model and the parametric model. Multicorrelation coefficient between observed value and estimated value was 0.87 and standard deviation was + or - 15%. Vegetation cover in Tokyo was mapped into five levels with equal intervals of 20%.

  15. Exploring Environmental Identity and Behavioral Change in an Environmental Science Course

    ERIC Educational Resources Information Center

    Blatt, Erica N.

    2013-01-01

    This ethnographic study at a public high school in the Northeastern United States investigates the process of change in students' environmental identity and proenvironmental behaviors during an Environmental Science course. The study explores how sociocultural factors, such as students' background, social interactions, and classroom structures,…

  16. Changes in metabolic modules under environmental variations

    NASA Astrophysics Data System (ADS)

    Almaas, Eivind

    2006-03-01

    During the last few years, network approaches have shown great promise as a tool to both analyze and provide understanding of complex systems as disparate as the world-wide web and cellular metabolism. Much effort has been focused on characterizing topological properties of such systems. However, in order to develop detailed descriptions of complex networks, we need to look beyond their topology and incorporate dynamical aspects. The cellular metabolism, where nodes correspond to metabolites and links indicate chemical reactions, is an excellent model system where theoretical predictions can be compared with experimental results. I will present recent insights into the principles governing the modular utilization of the cellular metabolism [1,2,3]. We find that, while most metabolic reactions have small fluxes, the metabolism's activity is dominated by an interconnected sub-network of reactions with very high fluxes [1]. For the bacteria H. pylori and E. coli and the yeast S. cerevisiae, the metabolism responds to changes in growth conditions by reorganizing the rates of select reactions predominantly within this high-flux backbone. Furthermore, these networks are organized around the metabolic core -- a set of reactions that are always in use [2]. Strikingly, the activity of the metabolic core reactions is highly synchronized, and the core reactions are significantly more essential and evolutionary conserved than the non-core ones. [1] E. Almaas, B. Kovacs, T. Vicsek, Z.N. Oltvai and A.-L. Barabasi. Nature 427, 839 (2004). [2] E. Almaas, Z.N. Oltvai and A.-L. Barabasi. PLoS Comput. Biol. In press (2005). 10.1371/journal.pcbi.0010068.eor [3] P.J. Macdonald, E. Almaas and A.-L. Barabasi. Europhys. Lett. 72, 308 (2005).

  17. Environmental Sustainability Change Management in SMEs: Learning from Sustainability Champions

    ERIC Educational Resources Information Center

    Chadee, Doren; Wiesner, Retha; Roxas, Banjo

    2011-01-01

    This study identifies the change management processes involved in undertaking environmental sustainability (ES) initiatives within Small and Medium Size Enterprises (SMEs) and relate these to the main attributes of learning organisations. Using case study techniques, the study draws from the change management experiences of a sample of 12 ES…

  18. Environmentalism unbound: reconnecting and re-envisioning movements for change.

    PubMed

    Gottlieb, R

    2001-01-01

    Disputes over environmental discourse have generated divergent pathways and discordant messages over the last three decades. An examination of them becomes a study of environmentalism s roots. The workplace is shown as a hidden and often discounted arena of debate about what constitutes an environmental issue. The triumph of the productionist and limitless consumption views helped to establish a focus on environmental change as a form of consumer action. Since the 1970s though, new forms of environmental discourse and action both community- and production-related have sought to shift the terrain. The possibility of becoming a broader, more socially inclusive movement capable of challenging the very structure and logic of capitalist social order is possible again, including the ability to identify new strategies for action. Overcoming the work/environment divide is perhaps the most contentious question facing the future of the environmental and labor movements. New approaches, including developing a community of interests, revaluing work, and developing an ethic of place (with urban, industrial, and global forms), require that the social and the ecological become joined in the construction of a common vision. When any environmental issue can be seen as socially determined, then environmentalism s great task will be to see itself as a primary agent of social change.

  19. Ceramic production during changing environmental/climatic conditions

    NASA Astrophysics Data System (ADS)

    Oestreich, Daniela B.; Glasmacher, Ulrich A.

    2015-04-01

    Ceramics, with regard to their status as largely everlasting everyday object as well as on the basis of their chronological sensitivity, reflect despite their simplicity the technological level of a culture and therefore also, directly or indirectly, the adaptability of a culture with respect to environmental and/or climatic changes. For that reason the question arises, if it is possible to identify changes in production techniques and raw material sources for ceramic production, as a response to environmental change, e.g. climate change. This paper will present results of a research about Paracas Culture (800 - 200 BC), southern Peru. Through several investigations (e.g. Schittek et al., 2014; Eitel and Mächtle, 2009) it is well known that during Paracas period changes in climate and environmental conditions take place. As a consequence, settlement patterns shifted several times through the various stages of Paracas time. Ceramics from three different sites (Jauranga, Cutamalla, Collanco) and temporal phases of the Paracas period are detailed archaeometric, geochemical and mineralogical characterized, e.g. Raman spectroscopy, XRD, and ICP-MS analyses. The aim of this research is to resolve potential differences in the chemical composition of the Paracas ceramics in space and time and to compare the data with the data sets of pre-Columbian environmental conditions. Thus influences of changing environmental conditions on human societies and their cultural conditions will be discussed. References Eitel, B. and Mächtle, B. 2009. Man and Environment in the eastern Atacama Desert (Southern Peru): Holocene climate changes and their impact on pre-Columbian cultures. In: Reindel, M. & Wagner, G. A. (eds.) New Technologies for Archaeology. Berlin Heidelberg: Springer-Verlag. Schittek, K., Mächtle, B., Schäbitz, F., Forbriger, M., Wennrich, V., Reindel, M., and Eitel, B.. Holocene environmental changes in the highlands of the southern Peruvian Andes (14° S) and their

  20. Predicting the response of populations to environmental change

    SciTech Connect

    Ives, A.R.

    1995-04-01

    When subject to long-term directional environmental perturbations, changes in population densities depend on the positive and negative feedbacks operating through interactions within and among species in a community. This paper develops techniques to predict the long-term responses of population densities to environmental changes using data on short-term population fluctuations driven by short-term environmental variability. In addition to giving quantitative predictions, the techniques also reveal how different qualitative patterns of species interactions either buffer or accentuate population responses to environmental trends. All of the predictions are based on regression coefficients extracted from time series data, and they can therefore be applied with a minimum of mathematical and statistical gymnastics. 48 refs., 10 figs., 4 tabs.

  1. A high-resolution temporal record of environmental changes in the Eastern Caribbean (Guadeloupe) from 40 to 10 ka BP

    NASA Astrophysics Data System (ADS)

    Royer, Aurélien; Malaizé, Bruno; Lécuyer, Christophe; Queffelec, Alain; Charlier, Karine; Caley, Thibaut; Lenoble, Arnaud

    2017-01-01

    In neotropical regions, fossil bat guano accumulated over time as laminated layers in caves, hence providing a high-resolution temporal record of terrestrial environmental changes. Additionally, cave settings have the property to preserve such organic sediments from processes triggered by winds (deflation, abrasion and sandblasting) and intense rainfall (leaching away). This study reports both stable carbon and nitrogen isotope compositions of frugivorous bat guano deposited in a well-preserved stratigraphic succession of Blanchard Cave on Marie-Galante, Guadeloupe. These isotopic data are discussed with regard to climate changes and its specific impact on Eastern Caribbean vegetation during the Late Pleistocene from 40 to 10 ka cal. BP. Guano δ13C values are higher than modern ones, suggesting noticeable vegetation changes. This provides also evidence for overall drier environmental conditions during the Pleistocene compared to today. Meanwhile, within this generally drier climate, shifts between wetter and drier conditions can be observed. Large temporal amplitudes in both δ13C and δ15N variations reaching up to 5.9‰ and 16.8‰, respectively, also indicate these oceanic tropical environments have been highly sensitive to regional or global climatic forcing. Stable isotope compositions of bat guano deposited from 40 to 35 ka BP, the Last Glacial Maximum and the Younger-Dryas reveal relatively wet environmental conditions whereas, at least from the end of the Heinrich event 1 and the Bølling period the region experienced drier environmental conditions. Nevertheless, when considering uncertainties in the model age, the isotopic record of Blanchard Cave show relatively similar variations with known proxy records from the northern South America and Central America, suggesting thus that the Blanchard Cave record is a robust proxy of past ITCZ migration. Teleconnections through global atmospheric pattern suggest that islands of the eastern Caribbean Basin could

  2. The effect of climate and environmental change on the megafaunal moa of New Zealand in the absence of humans

    NASA Astrophysics Data System (ADS)

    Rawlence, Nicolas J.; Metcalf, Jessica L.; Wood, Jamie R.; Worthy, Trevor H.; Austin, Jeremy J.; Cooper, Alan

    2012-09-01

    New Zealand offers a unique opportunity to investigate the response of extinct megafaunal ecosystems to major changes in climate and habitat prior to human settlement. Prior to this point (late 13th Century AD) New Zealand contained a diverse avian megafauna dominated by nine species of large flightless ratite moa (Dinornithiformes). We used ancient DNA approaches to generate mitochondrial DNA sequence data from 39 crested moa (Pachyornis australis) and 145 heavy-footed moa (Pachyornis elephantopus) specimens. In combination with radiocarbon dating and dietary isotope analysis we examined the effects of Late Pleistocene and Holocene climate and environmental change on the phylogeography, palaeodemographics, and eventual extinction of Pachyornis. We show that Pachyornis changed altitudinal, longitudinal and latitudinal ranges through the Late Quaternary in response to alterations in the distribution of suitable habitat. However, we found no evidence for large-scale change in population sizes during the past 40,000 radiocarbon years BP (approximately 44,000 calendar years BP), or significant changes in δ13C and δ15N isotope signatures over this time period. The results suggest that crested moa tracked habitat through time with little consequence to population size. For the more broadly distributed heavy-footed moa, changes in climate and habitat distribution may have promoted phylogeographic structuring. Overall this study suggests that the likelihood of megafaunal extinction in New Zealand was greatly reduced in the absence of humans.

  3. Ancient DNA analyses exclude humans as the driving force behind late Pleistocene musk ox (Ovibos moschatus) population dynamics.

    PubMed

    Campos, Paula F; Willerslev, Eske; Sher, Andrei; Orlando, Ludovic; Axelsson, Erik; Tikhonov, Alexei; Aaris-Sørensen, Kim; Greenwood, Alex D; Kahlke, Ralf-Dietrich; Kosintsev, Pavel; Krakhmalnaya, Tatiana; Kuznetsova, Tatyana; Lemey, Philippe; MacPhee, Ross; Norris, Christopher A; Shepherd, Kieran; Suchard, Marc A; Zazula, Grant D; Shapiro, Beth; Gilbert, M Thomas P

    2010-03-23

    The causes of the late Pleistocene megafaunal extinctions are poorly understood. Different lines of evidence point to climate change, the arrival of humans, or a combination of these events as the trigger. Although many species went extinct, others, such as caribou and bison, survived to the present. The musk ox has an intermediate story: relatively abundant during the Pleistocene, it is now restricted to Greenland and the Arctic Archipelago. In this study, we use ancient DNA sequences, temporally unbiased summary statistics, and Bayesian analytical techniques to infer musk ox population dynamics throughout the late Pleistocene and Holocene. Our results reveal that musk ox genetic diversity was much higher during the Pleistocene than at present, and has undergone several expansions and contractions over the past 60,000 years. Northeast Siberia was of key importance, as it was the geographic origin of all samples studied and held a large diverse population until local extinction at approximately 45,000 radiocarbon years before present ((14)C YBP). Subsequently, musk ox genetic diversity reincreased at ca. 30,000 (14)C YBP, recontracted at ca. 18,000 (14)C YBP, and finally recovered in the middle Holocene. The arrival of humans into relevant areas of the musk ox range did not affect their mitochondrial diversity, and both musk ox and humans expanded into Greenland concomitantly. Thus, their population dynamics are better explained by a nonanthropogenic cause (for example, environmental change), a hypothesis supported by historic observations on the sensitivity of the species to both climatic warming and fluctuations.

  4. Middle-Upper Pleistocene climate changes shaped the divergence and demography of Cycas guizhouensis (Cycadaceae): Evidence from DNA sequences and microsatellite markers.

    PubMed

    Feng, Xiuyan; Zheng, Ying; Gong, Xun

    2016-06-07

    Climatic oscillations in the Pleistocene have had profound effects on the demography and genetic diversity of many extant species. Cycas guizhouensis Lan &R.F. Zou is an endemic and endangered species in Southwest China that is primarily distributed along the valleys of the Nanpan River. In this study, we used four chloroplast DNAs (cpDNA), three nuclear genes (nDNA) and 13 microsatellite (SSR) loci to investigate the genetic structure, divergence time and demographic history of 11 populations of C. guizhouensis. High genetic diversity and high levels of genetic differentiation among the populations were observed. Two evolutionary units were revealed based on network and Structure analysis. The divergence time estimations suggested that haplotypes of C. guizhouensis were diverged during the Middle-Upper Pleistocene. Additionally, the demographic histories deduced from different DNA sequences were discordant, but overall indicated that C. guizhouensis had experienced a recent population expansion during the post-glacial period. Microsatellite data revealed that there was a contraction in effective population size in the past. These genetic features allow conservation measures to be taken to ensure the protection of this endangered species from extinction.

  5. Middle-Upper Pleistocene climate changes shaped the divergence and demography of Cycas guizhouensis (Cycadaceae): Evidence from DNA sequences and microsatellite markers

    PubMed Central

    Feng, Xiuyan; Zheng, Ying; Gong, Xun

    2016-01-01

    Climatic oscillations in the Pleistocene have had profound effects on the demography and genetic diversity of many extant species. Cycas guizhouensis Lan & R.F. Zou is an endemic and endangered species in Southwest China that is primarily distributed along the valleys of the Nanpan River. In this study, we used four chloroplast DNAs (cpDNA), three nuclear genes (nDNA) and 13 microsatellite (SSR) loci to investigate the genetic structure, divergence time and demographic history of 11 populations of C. guizhouensis. High genetic diversity and high levels of genetic differentiation among the populations were observed. Two evolutionary units were revealed based on network and Structure analysis. The divergence time estimations suggested that haplotypes of C. guizhouensis were diverged during the Middle-Upper Pleistocene. Additionally, the demographic histories deduced from different DNA sequences were discordant, but overall indicated that C. guizhouensis had experienced a recent population expansion during the post-glacial period. Microsatellite data revealed that there was a contraction in effective population size in the past. These genetic features allow conservation measures to be taken to ensure the protection of this endangered species from extinction. PMID:27270859

  6. Adaptive radiation within New Zealand endemic species of the cockroach genus Celatoblatta Johns (Blattidae): a response to Plio-Pleistocene mountain building and climate change.

    PubMed

    Chinn, Warren G; Gemmell, Neil J

    2004-06-01

    The South Island of New Zealand offers unique opportunities to study insect evolution due to long-term physical isolation, recent alpine habitats and high levels of biotic endemism. Using DNA sequence data from cytochrome oxidase subunit 1, we investigated the phylogeographical pattern among 10 endemic cockroach species within the genus Celatoblatta Johns (Blattidae). We tested the hypothesis that an ancestral cockroach species underwent rapid speciation in response to major climatic differentiation induced by mountain building. Results suggest that speciation was a twofold process, with an interspecific radiation of Pliocene/Pleistocene age followed by intraspecific diversification during the mid Pleistocene. Average genetic distance (maximum likelihood GTR + I + Gamma) was 9.17%, with a maximum of 14.5%. Data revealed eight deep well-supported branches, each with terminal clades. Six clades were differentiated according to morphological species, while the seventh was composed of three sympatric species. We consider the latter to be a phylogenetic species, possibly as a result of hybridization within a defined geographical area. This finding seriously challenges species distinctions for these three cockroach species. Correlation between genetic distances and a Climate Similarity Index (CSI) was negative, suggesting that species found in similar habitats are also genetically closely related. A Mantel test on within-clade genetic distances vs. linear geographical distance was positive, suggesting allopatric isolation for those haplotypes. We present a model of speciation for South Island Celatoblatta.

  7. Global Environmental Change: Modifying Human Contributions Through Education

    NASA Astrophysics Data System (ADS)

    Carter, Lynne M.

    1998-12-01

    The 1995 Intergovernmental Panel on Climate Change (IPCC, 1996) Science report concludes that evidence now available "points toward a discernible human influence on global climate" (p. 439). Reductions in emissions will require changes in human behavior. This study assessed whether gains in global environmental change knowledge would lead to changes in human behaviors that could be deemed environmentally responsible. The study assessed the impact on participant behavior of a two-and-one-half day National Informal Educators Workshop and Videoconference held November 14-16, 1994. The workshops were located in seven down-link sites around the continental U.S. and Hawaii. The program utilized a variety of pedagogical techniques during five hours of satellite programming with national expertise on global change topics (natural variability, greenhouse effect, ozone depletion, ecosystem response, and population and resource distribution) and applications of that information with local experts in regional workshops. Participants implemented many personal and professional behavior changes after participation in this program. Six behavior change scales were created from assessment of survey responses (four coefficient alphas were above .7, one was .68, and one was .58). Personal behavior changes grouped into three categories: Use of Fewer Resources (acts of everyday life generally under volitional control), Purchasing Choices/Options (less frequent acts, not under total volitional control, with significant environmental effect over the lifetime of the decision, e.g., an automobile) and Increased Awareness and Discussion (indicating changes in "habits of mind"). The professional behavior changes also grouped into three categories: Curriculum Development (developing/revising curricula including new knowledge); Networking (with colleagues from the program); and Office Procedures (reflecting environmentally responsible behavior). The statistically significant behavior changes

  8. Can environmental change affect host/parasite-mediated speciation?

    PubMed

    Brunner, Franziska S; Eizaguirre, Christophe

    2016-08-01

    Parasitism can be a driver of species divergence and thereby significantly alter species formation processes. While we still need to better understand how parasite-mediated speciation functions, it is even less clear how this process is affected by environmental change. Both rapid and gradual changes of the environment can modify host immune responses, parasite virulence and the specificity of their interactions. They will thereby change host-parasite evolutionary trajectories and the potential for speciation in both hosts and parasites. Here, we summarise mechanisms of host-parasite interactions affecting speciation and subsequently consider their susceptibility to environmental changes. We mainly focus on the effects of temperature change and nutrient input to ecosystems as they are major environmental stressors. There is evidence for both disruptive and accelerating effects of those pressures on speciation that seem to be context-dependent. A prerequisite for parasite-driven host speciation is that parasites significantly alter the host's Darwinian fitness. This can rapidly lead to divergent selection and genetic adaptation; however, it is likely preceded by more short-term plastic and transgenerational effects. Here, we also consider how these first responses and their susceptibility to environmental changes could lead to alterations of the species formation process and may provide alternative pathways to speciation.

  9. Zoonosis emergence linked to agricultural intensification and environmental change.

    PubMed

    Jones, Bryony A; Grace, Delia; Kock, Richard; Alonso, Silvia; Rushton, Jonathan; Said, Mohammed Y; McKeever, Declan; Mutua, Florence; Young, Jarrah; McDermott, John; Pfeiffer, Dirk Udo

    2013-05-21

    A systematic review was conducted by a multidisciplinary team to analyze qualitatively best available scientific evidence on the effect of agricultural intensification and environmental changes on the risk of zoonoses for which there are epidemiological interactions between wildlife and livestock. The study found several examples in which agricultural intensification and/or environmental change were associated with an increased risk of zoonotic disease emergence, driven by the impact of an expanding human population and changing human behavior on the environment. We conclude that the rate of future zoonotic disease emergence or reemergence will be closely linked to the evolution of the agriculture-environment nexus. However, available research inadequately addresses the complexity and interrelatedness of environmental, biological, economic, and social dimensions of zoonotic pathogen emergence, which significantly limits our ability to predict, prevent, and respond to zoonotic disease emergence.

  10. Mathematical classification of regulatory logics for compound environmental changes.

    PubMed

    Tanaka, Reiko J; Kimura, Hidenori

    2008-03-21

    This paper is concerned with biological regulatory mechanisms in response to the simultaneous occurrence of a huge number of environmental changes. The restricted resources of cells strictly limit the number of their regulatory methods; hence, cells must adopt, as compensation, special mechanisms to deal with the simultaneous occurrence of environmental changes. We hypothesize that cells use various control logics to integrate information about independent environmental changes related to a cell task and represent the resulting effects of the different ways of integration by logical functions. Using the notion of equivalence classes in set theory, we describe the mathematical classification of the effects into biologically unequivalent ones realized by different control logics. Our purely mathematical and systematic classification of logical functions reveals three elementary control logics with different biological relevance. To better understand their biological significance, we consider examples of biological systems that use these elementary control logics.

  11. Effects of extreme environmental changes on population dynamics

    NASA Astrophysics Data System (ADS)

    De Falco, I.; Della Cioppa, A.; Tarantino, E.

    2006-09-01

    The effects of periodic environmental fluctuations on the adaptive behavior and on the survival chance of a population of individuals are investigated as a function of both the genotypes carried, i.e., haploid or diploid. Only extreme and exogenous changes have been taken into account in order not to complicate the model under investigation. Moreover, different rates of both environmental changes and mutation have been considered. The analysis has been performed by discussing the evolutionary dynamics exhibited by the population in terms of adaptation, density and, finally, survival probability.

  12. Inuit Perspectives on Arctic Environmental Change': A Traveling Exhibition

    NASA Astrophysics Data System (ADS)

    Sheffield, E. M.; Hakala, J. S.; Gearheard, S.

    2006-12-01

    The Inuit of Nunavut, Canada, have an intimate relationship with their surroundings. As a culture that relies on knowledge of sea ice, snow, and weather conditions for success in hunting, fishing, and healthy wellbeing, Inuit have observed and studied environmental patterns for generations. An ongoing study into their traditional knowledge and their observations of environmental change is being conducted by researcher Dr. Shari Gearheard, who has worked with Inuit communities in Nunavut for over a decade. The results of the research have been published in scientific journals, and to communicate the results to a broader audience, Dr. Gearheard designed an interactive CD-ROM displaying photographs, maps, and interview videos of Inuit Elders' perspectives on the changes they have witnessed. Receiving immediate popularity since its release in 2004, copies of `When the Weather is Uggianaqtuq: Inuit Observations of Environmental Change' have been distributed worldwide, to indigenous peoples, social science and climate change researchers, teachers, students, and the general public. To further disseminate the information contained on the CD-ROM, the National Snow and Ice Data Center and the Museum of Natural History, both of the University of Colorado, are partnering to create an exhibition which will open at the Museum during the International Polar Year in April 2008. The exhibit, tentatively titled `Inuit Perspectives on Arctic Environmental Change,' will feature photographs, graphics, and text in both English and Inuktitut describing environmental change in the North. The goals are to make the information and interpretation contained on the CD-ROM available and more accessible to a broad audience and to raise awareness about Arctic climate change and the important contribution of Inuit knowledge. Following exhibition at the Museum, the exhibit will travel throughout the United States, Alaska, and Nunavut, through a network of museums, schools, libraries, tribal

  13. Coastal geoindicators of environmental change in the humid tropics

    USGS Publications Warehouse

    Morton, R.A.

    2002-01-01

    The primary geoindicators appropriate for monitoring environmental changes in the humid tropics are transitory surface water levels, shoreline position, wetlands distribution, coral reefs, landforms, and sediment sequence and composition. Lateral zonations and temporal successions of vegetation also can be used as geoindicators of riverine and shoreline changes. All of these coastal geoindicators are sensitive to regional tectonic processes and anthropogenic alterations and they typically reflect significant changes in coastal conditions such as fluvial processes, coastal energy, water quality, relative sea level, and sediment supply. Where humid tropical coasts coincide with active tectonic margins, indicators of seismic activity are critical to understanding Coastal changes associated with co-seismic subsidence or uplift, tsunamis, and liquefaction of coastal sediments. Coastal landforms and sedimentary deposits that record late Quaternary environmental changes include perched fluvial and marine terraces, delta-plain morphologies, crevassesplay deposits, peats and other paleosols, beach ridges, mud capes, and mud volcanoes. Although these features and deposits typically reflect environmental changes spanning more than 100 years, they are relevant to modern processes, management of coastal lands and resources, and prediction of future conditions. In some regions of the humid tropics, large coastal areas are unaffected by hurricanes or typhoons. Nevertheless, these tropical coasts are vulnerable to other non-storm processes, such as El Nin??o events, tsunamis, and monsoons that increase water levels, and cause widespread flooding and beach erosion. The environmental and political significance of coastal geoindicators increases when they are integrated and applied to issues of human safety and health such as hazards mapping, risk assessment, and dispersion of contaminated sediments. However, to be relevant, those socio-environmental applications demand accurate

  14. Delivering Global Environmental Change Science Through Documentary Film

    NASA Astrophysics Data System (ADS)

    Dodgson, K.; Byrne, J. M.; Graham, J. R.

    2010-12-01

    Communicating authentic science to society presents a significant challenge to researchers. This challenge stems from unfortunate misrepresentation and misunderstanding in the mainstream media, particularly in relation to science on global environmental change. This has resulted in a lower level of confidence and interest amongst audiences in regards to global environmental change and anthropogenic climate change discussions. This project describes a new form of documentary film that aspires to break this trend and increase audiences’ interest, reinvigorating discussion about global environmental change. The documentary film adopts a form that marries traditional scientific presentation with the high entertainment value of narrative storytelling. This format maintains the authenticity of the scientific message and ensures audience engagement throughout the entire presentation due to the fact that a sense of equality and intimacy between the audience and the scientists is achieved. The film features interviews with scientists studying global environmental change and opens with a comparison of authentic scientific information and the mainstream media’s presentation, and subsequent public opinion. This enables an analysis of the growing disconnect between society and the scientific community. Topics investigated include: Arctic ice melt, coastal zone hypoxia, tropical cyclones and acidification. Upon completion of the film, public and private screenings with predetermined audience demographics will be conducted using a short, standardized survey to gain feedback regarding the audience’s overall review of the presentation. In addition to the poster, this presentation features an extended trailer for the documentary film.

  15. The impact of large terrestrial carnivores on Pleistocene ecosystems.

    PubMed

    Van Valkenburgh, Blaire; Hayward, Matthew W; Ripple, William J; Meloro, Carlo; Roth, V Louise

    2016-01-26

    Large mammalian terrestrial herbivores, such as elephants, have dramatic effects on the ecosystems they inhabit and at high population densities their environmental impacts can be devastating. Pleistocene terrestrial ecosystems included a much greater diversity of megaherbivores (e.g., mammoths, mastodons, giant ground sloths) and thus a greater potential for widespread habitat degradation if population sizes were not limited. Nevertheless, based on modern observations, it is generally believed that populations of megaherbivores (>800 kg) are largely immune to the effects of predation and this perception has been extended into the Pleistocene. However, as shown here, the species richness of big carnivores was greater in the Pleistocene and many of them were significantly larger than their modern counterparts. Fossil evidence suggests that interspecific competition among carnivores was relatively intense and reveals that some individuals specialized in consuming megaherbivores. To estimate the potential impact of Pleistocene large carnivores, we use both historic and modern data on predator-prey body mass relationships to predict size ranges of their typical and maximum prey when hunting as individuals and in groups. These prey size ranges are then compared with estimates of juvenile and subadult proboscidean body sizes derived from extant elephant growth data. Young proboscideans at their most vulnerable age fall within the predicted prey size ranges of many of the Pleistocene carnivores. Predation on juveniles can have a greater impact on megaherbivores because of their long interbirth intervals, and consequently, we argue that Pleistocene carnivores had the capacity to, and likely did, limit megaherbivore population sizes.

  16. The impact of large terrestrial carnivores on Pleistocene ecosystems

    PubMed Central

    Van Valkenburgh, Blaire; Ripple, William J.; Meloro, Carlo; Roth, V. Louise

    2016-01-01

    Large mammalian terrestrial herbivores, such as elephants, have dramatic effects on the ecosystems they inhabit and at high population densities their environmental impacts can be devastating. Pleistocene terrestrial ecosystems included a much greater diversity of megaherbivores (e.g., mammoths, mastodons, giant ground sloths) and thus a greater potential for widespread habitat degradation if population sizes were not limited. Nevertheless, based on modern observations, it is generally believed that populations of megaherbivores (>800 kg) are largely immune to the effects of predation and this perception has been extended into the Pleistocene. However, as shown here, the species richness of big carnivores was greater in the Pleistocene and many of them were significantly larger than their modern counterparts. Fossil evidence suggests that interspecific competition among carnivores was relatively intense and reveals that some individuals specialized in consuming megaherbivores. To estimate the potential impact of Pleistocene large carnivores, we use both historic and modern data on predator–prey body mass relationships to predict size ranges of their typical and maximum prey when hunting as individuals and in groups. These prey size ranges are then compared with estimates of juvenile and subadult proboscidean body sizes derived from extant elephant growth data. Young proboscideans at their most vulnerable age fall within the predicted prey size ranges of many of the Pleistocene carnivores. Predation on juveniles can have a greater impact on megaherbivores because of their long interbirth intervals, and consequently, we argue that Pleistocene carnivores had the capacity to, and likely did, limit megaherbivore population sizes. PMID:26504224

  17. Environmental change and fire in the Owen Stanley Ranges, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Hope, Geoffrey

    2009-11-01

    Kosipe, an upland valley at 2000 m altitude in the Owen Stanley Ranges of southeastern New Guinea, is known for the discovery of large stone waisted blades dated to 31 400 cal a BP. The purpose of these tools and the nature of occupation are unknown. The altitude is too high for most food crops today and may have stood close to the treeline during the last glaciation. Three pollen and charcoal diagrams from a large swamp in the Kosipe Valley provide a record of swamp and dryland changes for more than 50 000 years. There have been considerable fluctuations in vegetation on the slopes and on the swamp which reflect both environmental change and anthropogenic influences. A gymnosperm-rich forest at the base is replaced by mountain forest dominated by Nothofagus about 42 000 years ago. Fire first becomes apparent across the swamp around 40 000 years ago but is not common during the time when subalpine herbs reach their best representation. Tree fern-rich grasslands form a mosaic with montane forest in a near-treeline environment. The Pleistocene-Holocene boundary is marked by a decline in Nothofagus and increase in lower montane mixed forest taxa. Charcoal increases before this time and the swamp vegetation becomes more grass-rich. Charcoal is at its maximum through the last 3000 years possibly reflecting climate variability as well as sedentary occupation and agriculture on the swamp margin. Supplementary pollen diagrams from two higher altitude sites support the evidence from the Kosipe Swamp cores. Charcoal, local catchment erosion and increases in disturbance taxa become more widespread in the last 5000 years at these sites, suggesting that local settlement at Kosipe may have lagged behind general landscape use by populations from lower altitudes.

  18. Environmental change and peatland forest dynamics in the Lake Sentarum area, West Kalimantan, Indonesia

    NASA Astrophysics Data System (ADS)

    Anshari, Gusti; Kershaw, A. Peter; van der Kaars, Sander; Jacobsen, Geraldine

    2004-10-01

    Four short pollen and charcoal records from sites within and around Lake Pemerak on the margins of the Danau (Lake) Sentarum National Park in inland West Kalimantan, supported by modern surface samples from the Reserve, provide a partial picture of lowland equatorial vegetation and environments over at least the last 40 000 years. They demonstrate general stability in the distribution of wetland and ombrotrophic (or raised) peatlands through the recorded period with dominance throughout of peatland and swamp forest. However, there was marked variation in sediment accumulation rates and in the floristic composition of the vegetation. The period prior to the last glacial maximum appears to have been the time of most active peatland growth and contrasts with the perception, from previous studies on largely coastal and subcoastal peatlands in Indonesia, that the Holocene was the time of major tropical peat accumulation. A general increase in charcoal, just prior to about 30 000 years ago, suggests that burning became more frequent, and is attributed to initial human impact rather than climate change. The subsequent latest Pleistocene period, embracing the Last Glacial Maximum, is marked by a peak in montane-submontane rainforest taxa, strongly indicating a substantial lowering of temperature. It appears that much of the Holocene is not recorded but recommencement of peat accumulation is evident within the last few thousand years. At the time of fieldwork access to the central part of the Lake Sentarum system was inhibited by strong El Niño drought conditions, but this area has the potential to provide a longer and more continuous history of environmental change for the region. Copyright

  19. Climate change and environmental concentrations of POPs: A review.

    PubMed

    Nadal, Martí; Marquès, Montse; Mari, Montse; Domingo, José L

    2015-11-01

    In recent years, the climate change impact on the concentrations of persistent organic pollutants (POPs) has become a topic of notable concern. Changes in environmental conditions such as the increase of the average temperature, or the UV-B radiation, are likely to influence the fate and behavior of POPs, ultimately affecting human exposure. The state of the art of the impact of climate change on environmental concentrations of POPs, as well as on human health risks, is here reviewed. Research gaps are also identified, while future studies are suggested. Climate change and POPs are a hot issue, for which wide attention should be paid not only by scientists, but also and mainly by policy makers. Most studies reported in the scientific literature are focused on legacy POPs, mainly polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and pesticides. However, the number of investigations aimed at estimating the impact of climate change on the environmental levels of polycyclic aromatic hydrocarbons (PAHs) is scarce, despite of the fact that exposure to PAHs and photodegradation byproducts may result in adverse health effects. Furthermore, no data on emerging POPs are currently available in the scientific literature. In consequence, an intensification of studies to identify and mitigate the indirect effects of the climate change on POP fate is needed to minimize the human health impact. Furthermore, being this a global problem, interactions between climate change and POPs must be addressed from an international perspective.

  20. Ecospaces occupied by Homo erectus and Homo sapiens in insular Southeast Asia in the Pleistocene

    NASA Astrophysics Data System (ADS)

    Hertler, Christine; Haupt, Susanne; Volmer, Rebekka; Bruch, Angela

    2014-05-01

    Hominins migrated to the islands of the Sunda Shelf multiple times. At least two immigration events are evident, an early immigration of Homo erectus in the late Early Pleistocene and a second immigration of Homo sapiens during the Late Pleistocene. Regional environments changed considerably in the Pleistocene. Expansion patterns among hominins are at least co-determined by their ecologies and environmental change. We examine these expansion patterns on the basis of habitat reconstructions. Mammalian communities provide a geographically extensive record and permit to assess hominin ecospaces. Although chronological resolution is low, they represent the most complete record of habitat changes associated with hominin expansion patterns. In order to reconstruct and compare hominin ecospaces on a quantitative scale, we set up a reference sample consisting of mammalian communities of 117 national parks in South Asia and Sub-Saharan Africa. The diversity of such communities is assessed by ecological profiling of specialized herbivore taxa. Moreover, datasets on climate and vegetation correlate with the diversity structure of such specialized herbivore communities. Reconstructing the diversity structure of communities at key sites in Pleistocene Southeast Asia permits to infer features of the climatic and vegetation framework associated with different hominin taxa. Our results show that Homo erectus and Homo sapiens did not occupy similar ecospaces. The ecospace of Homo erectus is characterized by comparatively low diversity among frugivorous and folivorous taxa, while obligate grazers are part of the assemblages. Specialized herbivore communities with such a diversity structure occur at present in East Africa, while they are absent in Southeast Asia. In the reference sample, this type of ecospace corresponds to seasonal wetlands. Although Homo sapiens still inhabits this type of environment in Southeast Asia, his ecospace is wider. Homo sapiens is associated with

  1. Water balance changes across environmental gradients in Sweden.

    NASA Astrophysics Data System (ADS)

    van der Velde, Y.; Lyon, S. W.; Vercauteren, N.; Destouni, G.

    2012-04-01

    Climate change, land use change and an increasing use of water for irrigation, industry, hydro power and consumption alter the water balance of many catchments. Such changes affect the water availability for ecosystems and humans but also affect hydrological conditions in downstream lakes and coastal zones. In the Baltic Sea region, for example, an increase in precipitation in Northern Sweden may reduce sea water salinity, while increasing evapotranspiration in the South, which is dominated by agriculture, may reduce nutrient leaching. Both changes will affect the Baltic Sea ecosystem. It thus is important to identify, for each region in Sweden, the dominant drivers for change to understand and anticipate future hydrological conditions in the Baltic Sea. In this study we have analyzed long term changes in the water balance for 250 catchments in Sweden. By quantifying the spatial correlation of these changes between catchments we were able to constrain measurement uncertainty in precipitation, discharge and catchment area. This allowed us to create reliable regional estimates of changes in precipitation, discharge and evapotranspiration for the period 1960-2010. The Bodyko framework was used to translate these water balance changes to water use efficiency trajectories across environmental gradients (latitude, elevation, agriculture and population). These trajectories in Bodyko-space help to identify the contributions of climate change and changes in water use efficiency to observed changes in the water balance. We show that within Sweden distinctly different trajectories of hydrological change occur and that these differences should be accounted for in climate change adaptation strategies.

  2. Exploring environmental identity and behavioral change in an Environmental Science course

    NASA Astrophysics Data System (ADS)

    Blatt, Erica N.

    2013-06-01

    This ethnographic study at a public high school in the Northeastern United States investigates the process of change in students' environmental identity and proenvironmental behaviors during an Environmental Science course. The study explores how sociocultural factors, such as students' background, social interactions, and classroom structures, impact the environmental identity and behavior of students. In this investigation, the identity theory of emotion of Stryker (2004) from the field of sociology is utilized in the interpretation of students' reactions to classroom experiences as they proceed through the Environmental Science course. The participants in this study are an Environmental Science teacher and the 10-12th grade students in her Environmental Science elective course. The researcher collected data for a period of six months, attending class on a daily basis. Data was collected through participant observation, videotaping, interviews, and cogenerative dialogues. The results of this study inform science educators by illuminating important elements, such as students' emotional responses to activities in class, conflicting elements of students' identities, and students' openness and willingness to critically reflect upon new information, which contribute to whether a student is likely to change their views towards the environment and pro-environmental behaviors.

  3. Environmental Change, Strategic Foresight, and Impacts on Military Power

    DTIC Science & Technology

    2010-01-01

    scenario planning, and in developing early warning systems for energy and environmental inse - curity.1 Rather than take a simplistic view of...case scenarios for emissions of greenhouse gases and physical changes, such as Arctic summer sea ice or Greenland ice sheet melt, were surpassed

  4. People and Environmental Changes. Teacher's Guide. Preparing for Tomorrow's World.

    ERIC Educational Resources Information Center

    Iozzi, Louis A.

    "People and Environmental Changes" is one of the "Preparing for Tomorrow's World" (PTW) program modules. PTW is an interdisciplinary, future-oriented program which incorporates information from the sciences and social sciences and addresses societal concerns which interface science/technology/society. The program promotes…

  5. Challenges to professionalism: Social accountability and global environmental change.

    PubMed

    Pearson, David; Walpole, Sarah; Barna, Stefi

    2015-01-01

    This article explores the concept of professionalism as it relates to social change and social accountability, and expands on them in the light of global environmental changes. Professionalism in medicine includes concepts of altruism, service, professional knowledge, self-regulation and autonomy. Current dialogues around social accountability suggest that medical schools should re-orientate their strategy and desired education, research and service outcomes to the health needs of the communities they serve.This article addresses the following questions: • How do we reconcile ideas of medical professionalism with the demands of creating a more equal, just, sustainable and socially inclusive society? • What new challenges do or will we face in relation to environmental degradation, biodiversity loss, ecosystem health and climate change? • How can medical schools best teach social and environmental responsiveness within a framework of professionalism? • How do medical schools ensure that tomorrow's doctors possess the knowledge, skills and attitude to adapt to the challenges they will face in future roles?We offer ideas about why and how medical educators can change, recommendations to strengthen the teaching of professionalism and social accountability and suggestions about the contribution of an emerging concept, that of "environmental accountability".

  6. People and Environmental Changes. [Student's Guide.] Preparing for Tomorrow's World.

    ERIC Educational Resources Information Center

    Iozzi, Louis A.; And Others

    The intent of this module is to engage students (grades 9-11) in an examination of issues that arise as a result of human activities in the physical environment. Activities are organized into two sections: the first focusing on weather modification and construction of dams as examples of planned environmental change and the second focusing on…

  7. Glacial-interglacial changes in equatorial Pacific surface-water structure during the Plio-Pleistocene intensification of Northern Hemisphere Glaciation

    NASA Astrophysics Data System (ADS)

    Jakob, Kim A.; Bolton, Clara T.; Wilson, Paul A.; Bahr, André; Pross, Jörg; Fiebig, Jens; Kähler, Karsten; Friedrich, Oliver

    2017-04-01

    The late Pliocene/early Pleistocene intensification of Northern Hemisphere Glaciation (iNHG) represents the most recent major tipping point in Earth's climate history. In the equatorial Pacific, the iNHG has been suggested to mark the transition from a warm Pliocene climate state, in which the Pacific warm pool was greatly expanded relative to today giving rise to a surface ocean temperature field akin to modern El Niño conditions, to a climate state with strong upwelling in the east of the basin and stronger zonal temperature gradients. Here we examine this transition by presenting new high-resolution (∼800 yr) planktic foraminiferal Mg/Ca- and δ18O-based sea-surface temperature (SST) and salinity (SSS; based on δ18 O residuals [δ18Oivc-sw]) records from Eastern Equatorial Pacific (EEP) Ocean Drilling Program Site 849 spanning ∼2.75-2.4 Ma. Our study interval contains the first large-amplitude (∼1‰ in benthic δ18O) early Pleistocene glacial-interglacial cycles (Marine Isotope Stages 100-96) representing the culmination of iNHG. In this study we investigate west-to-east equatorial Pacific SST and SSS gradients. We find that the zonal SST gradient increased by ∼1.5 °C from ∼2.75 to ∼2.4 Ma through EEP cooling. No glacial-interglacial pattern is seen in this gradient. On the other hand, we document obliquity-paced oscillations in the δ18Oivc-sw (SSS) gradient. We hypothesize that these oscillations originated from a response to a glacial southward and interglacial northward migration of the Intertropical Convergence Zone over the EEP.

  8. Pleistocene megafaunal interaction networks became more vulnerable after human arrival.

    PubMed

    Pires, Mathias M; Koch, Paul L; Fariña, Richard A; de Aguiar, Marcus A M; dos Reis, Sérgio F; Guimarães, Paulo R

    2015-09-07

    The end of the Pleistocene was marked by the extinction of almost all large land mammals worldwide except in Africa. Although the debate on Pleistocene extinctions has focused on the roles of climate change and humans, the impact of perturbations depends on properties of ecological communities, such as species composition and the organization of ecological interactions. Here, we combined palaeoecological and ecological data, food-web models and community stability analysis to investigate if differences between Pleistocene and modern mammalian assemblages help us understand why the megafauna died out in the Americas while persisting in Africa. We show Pleistocene and modern assemblages share similar network topology, but differences in richness and body size distributions made Pleistocene communities significantly more vulnerable to the effects of human arrival. The structural changes promoted by humans in Pleistocene networks would have increased the likelihood of unstable dynamics, which may favour extinction cascades in communities facing extrinsic perturbations. Our findings suggest that the basic aspects of the organization of ecological communities may have played an important role in major extinction events in the past. Knowledge of community-level properties and their consequences to dynamics may be critical to understand past and future extinctions.

  9. Environmental change challenges decision-making during post-market environmental monitoring of transgenic crops.

    PubMed

    Sanvido, Olivier; Romeis, Jörg; Bigler, Franz

    2011-12-01

    The ability to decide what kind of environmental changes observed during post-market environmental monitoring of genetically modified (GM) crops represent environmental harm is an essential part of most legal frameworks regulating the commercial release of GM crops into the environment. Among others, such decisions are necessary to initiate remedial measures or to sustain claims of redress linked to environmental liability. Given that consensus on criteria to evaluate 'environmental harm' has not yet been found, there are a number of challenges for risk managers when interpreting GM crop monitoring data for environmental decision-making. In the present paper, we argue that the challenges in decision-making have four main causes. The first three causes relate to scientific data collection and analysis, which have methodological limits. The forth cause concerns scientific data evaluation, which is controversial among the different stakeholders involved in the debate on potential impacts of GM crops on the environment. This results in controversy how the effects of GM crops should be valued and what constitutes environmental harm. This controversy may influence decision-making about triggering corrective actions by regulators. We analyse all four challenges and propose potential strategies for addressing them. We conclude that environmental monitoring has its limits in reducing uncertainties remaining from the environmental risk assessment prior to market approval. We argue that remaining uncertainties related to adverse environmental effects of GM crops would probably be assessed in a more efficient and rigorous way during pre-market risk assessment. Risk managers should acknowledge the limits of environmental monitoring programmes as a tool for decision-making.

  10. Potential environmental benefits of prospective genetic changes in broiler traits.

    PubMed

    Leinonen, I; Williams, A G; Kyriazakis, I

    2016-02-01

    A system approach-based Life Cycle Assessment (LCA) framework, combined with a simple mechanistic model of bird energy balance was used to predict the potential effects of 15 y prospective broiler breeding on the environmental impacts of the standard UK broiler production system. The year 2014 Ross 308 genotype was used as a baseline, and a future scenario was specified from rates of genetic improvement predicted by the industry. The scenario included changes in the traits of growth rate (reducing the time to reach a target weight 2.05 kg from 34 d to 27 d), body lipid content, carcass yield, mortality and the number of chicks produced by a breeder hen. Diet composition was adjusted in order to accommodate the future nutrient requirements of the birds following the genetic change. The results showed that predicted changes in biological performance due to selective breeding could lead to reduced environmental impacts of the broiler production chain, most notably in the Eutrophication Potential (by 12%), Acidification Potential (by 10%) and Abiotic Resource Use (by 9%) and Global Warming Potential (by 9%). These reductions were mainly caused by the reduced maintenance energy requirement and thus lower feed intake, resulting from the shorter production cycle, together with the increased carcass yield. However, some environmental benefits were limited by the required changes in feed composition (e.g., increased inclusion of soy meal and vegetable oil) as a result of the changes in bird nutrient requirements. This study is the first one aiming to link the mechanistic animal modeling approach to predicted genetic changes in order to produce quantitative estimates of the future environmental impacts of broiler production. Although a more detailed understanding on the mechanisms of the potential changes in bird performance and their consequences on feeding and husbandry would be still be needed, the modeling framework produced in this study provides a starting point for

  11. Drastic environmental change and its effects on a planetary biosphere

    NASA Astrophysics Data System (ADS)

    Schulze-Makuch, Dirk; Irwin, Louis N.; Fairén, Alberto G.

    2013-07-01

    Environmental conditions can change drastically and rapidly during the natural history of a planetary body. These changes affect the biosphere and can spur evolution via the mechanism of directional selection leading to the innovation of new processes and forms of life, or alternatively leading to the extinction of certain life forms. Based on the natural history of Earth, the effect on a planet's biosphere depends on three factors: (1) the nature and time scale of change, (2) the composition of the biosphere prior to change, and (3) the nature of the environment following the change. Though Earth has undergone various periods of drastic environmental change, life has shown an enormous resiliency and became more diverse and complex as a consequence of these events. Mars and Venus have undergone even larger environmental changes, both from habitable conditions under which the origin of life (or transfer of life from Earth) seem plausible, to a dry and cold planet punctuated by wetter conditions, and a hyperthermic greenhouse, respectively. Given its planetary history, life on Mars could have retreated to a psychrophilic lifestyle in the deep subsurface or to environmental near-surface niches, such as hydrothermal regions and caves. Further, strong directional selection could have pushed putative martian life to evolve alternating cycles between active and dormant forms, as well as the innovation of new traits adapted to challenging near-surface conditions. Life in the subsurface or on the surface of Venus seems impossible today, but microorganisms may have adapted to thrive in the lower cloud layer, possibly using a biochemical strategy analogous to Photosystem I and chemoautotrophic sulfur metabolism, and employing cycloocta sulfur for UV protection.

  12. Assessing future changes in pan-European environmental flows

    NASA Astrophysics Data System (ADS)

    Laize, C.; Hannah, D. M.

    2011-12-01

    The potential river flow-driven impact of change on aquatic and riparian ecosystems at the pan-European scale under various climatological and development scenarios was assessed using a methodology based conceptually on the Range of Variability Approach (RVA) using the Indicators of Hydrological Alteration (IHA): a desk-top technique for assessing if environmental flow requirements. This paper presents an adaptation of the IHA approach using monthly flows. European and Mediterranean river networks were modelled as ~35,000 cells (0.5° longitude x 0.5° latitude). For each cell, modelled monthly flows were generated for an ensemble of 10 future climate change scenarios. These scenarios consist of combinations of two climate scenarios (IPCM4 and MIMR) and four socio-economic water-use scenarios (each with a main driver of economy, policy, security, or sustainability), projected for 2050s. IHA-styled statistics were calculated. By tailoring the RVA, acceptable baseline environmental flow ranges and departures from these of the projected hydrological regimes were assessed and coded using a traffic-light system (green for environmental flows met, amber minor variation, red major variation). For the first time, the results show spatial patterns of flow change and associated potential river ecosystem impacts across the wider European continent. Importantly, the findings indicate that climate change may be a more influential driver than water-use change in determining future river ecosystem health . Patterns were also investigated against broad basin types to identify which are most or least at risk.

  13. Pleistocene aridification cycles shaped the contemporary genetic architecture of Southern African baboons.

    PubMed

    Sithaldeen, Riashna; Ackermann, Rebecca Rogers; Bishop, Jacqueline M

    2015-01-01

    Plio-Pleistocene environmental change influenced the evolutionary history of many animal lineages in Africa, highlighting key roles for both climate and tectonics in the evolution of Africa's faunal diversity. Here, we explore diversification in the southern African chacma baboon Papio ursinus sensu lato and reveal a dominant role for increasingly arid landscapes during past glacial cycles in shaping contemporary genetic structure. Recent work on baboons (Papio spp.) supports complex lineage structuring with a dominant pulse of diversification occurring 1-2Ma, and yet the link to palaeoenvironmental change remains largely untested. Phylogeographic reconstruction based on mitochondrial DNA sequence data supports a scenario where chacma baboon populations were likely restricted to refugia during periods of regional cooling and drying through the Late Pleistocene. The two lineages of chacma baboon, ursinus and griseipes, are strongly geographically structured, and demographic reconstruction together with spatial analysis of genetic variation point to possible climate-driven isolating events where baboons may have retreated to more optimum conditions during cooler, drier periods. Our analysis highlights a period of continuous population growth beginning in the Middle to Late Pleistocene in both the ursinus and the PG2 griseipes lineages. All three clades identified in the study then enter a state of declining population size (Nef) through to the Holocene; this is particularly marked in the last 20,000 years, most likely coincident with the Last Glacial Maximum. The pattern recovered here conforms to expectations based on the dynamic regional climate trends in southern Africa through the Pleistocene and provides further support for complex patterns of diversification in the region's biodiversity.

  14. Pleistocene Aridification Cycles Shaped the Contemporary Genetic Architecture of Southern African Baboons

    PubMed Central

    Sithaldeen, Riashna; Ackermann, Rebecca Rogers; Bishop, Jacqueline M.

    2015-01-01

    Plio-Pleistocene environmental change influenced the evolutionary history of many animal lineages in Africa, highlighting key roles for both climate and tectonics in the evolution of Africa’s faunal diversity. Here, we explore diversification in the southern African chacma baboon Papio ursinus sensu lato and reveal a dominant role for increasingly arid landscapes during past glacial cycles in shaping contemporary genetic structure. Recent work on baboons (Papio spp.) supports complex lineage structuring with a dominant pulse of diversification occurring 1-2Ma, and yet the link to palaeoenvironmental change remains largely untested. Phylogeographic reconstruction based on mitochondrial DNA sequence data supports a scenario where chacma baboon populations were likely restricted to refugia during periods of regional cooling and drying through the Late Pleistocene. The two lineages of chacma baboon, ursinus and griseipes, are strongly geographically structured, and demographic reconstruction together with spatial analysis of genetic variation point to possible climate-driven isolating events where baboons may have retreated to more optimum conditions during cooler, drier periods. Our analysis highlights a period of continuous population growth beginning in the Middle to Late Pleistocene in both the ursinus and the PG2 griseipes lineages. All three clades identified in the study then enter a state of declining population size (Nef) through to the Holocene; this is particularly marked in the last 20,000 years, most likely coincident with the Last Glacial Maximum. The pattern recovered here conforms to expectations based on the dynamic regional climate trends in southern Africa through the Pleistocene and provides further support for complex patterns of diversification in the region’s biodiversity. PMID:25970269

  15. Millennial-scale vegetation changes in the north-eastern Russian Arctic during the Pliocene/Pleistocene transition (2.7-2.5 Ma) inferred from the pollen record of Lake El'gygytgyn

    NASA Astrophysics Data System (ADS)

    Andreev, Andrei A.; Tarasov, Pavel E.; Wennrich, Volker; Melles, Martin

    2016-09-01

    The sediment record of Lake El'gygytgyn (67°30‧N, 172°05‧E) spans the past 3.6 Ma and provides unique opportunities for qualitative and quantitative reconstructions of the regional paleoenvironmental history of the terrestrial Arctic. Millennial-scale pollen studies of the sediments that accumulated during the Late Pliocene and Early Pleistocene (ca. 2.7 to 2.5 Ma) demonstrate orbitally-driven vegetation and climate changes during this transitional interval. Pollen spectra show a significant vegetation shift at the Pliocene/Pleistocene boundary that is, however, delayed by a few thousand years compared to lacustrine response. About 2.70-2.68 Ma the vegetation at Lake El'gygytgyn, currently a tundra area was mostly dominated by larch forests with some shrub pine, shrub alder and dwarf birch in understory. During the marine isotope stages G3 and G1, ca. 2.665-2.647 and 2.625-2.617 Ma, some spruce trees grew in the local larch-pine forests, pointing to relatively warm climate conditions. At the beginning of the Pleistocene, around 2.588 Ma, a prominent climatic deterioration led to a change from larch-dominated forests to predominantly treeless steppe- and tundra-like habitats. Between ca. 2.56-2.53 Ma some climate amelioration is reflected by the higher presence of coniferous taxa (mostly pine and larch, but probably also spruce) in the area. After 2.53 Ma a relatively cold and dry climate became dominant again, leading to open steppe-like and shrubby environments followed by climate amelioration between ca. 2.510 and 2.495 Ma, when pollen assemblages show that larch forests with dwarf birch and shrub alder still grew in the lake's vicinity. Increased contents of green algae colonies (Botryococcus) remains and Zygnema cysts around 2.691-2.689, 2.679-2.677, 2.601-2.594, 2.564-2.545, and 2.532-2.510 Ma suggest a spread of shallow-water environments most likely due to a lake-level lowering. These events occurred simultaneously with dry climate conditions inferred

  16. Evolution of a Planktonic Foraminifer during Environmental Changes in the Tropical Oceans

    PubMed Central

    Ujiié, Yurika; Ishitani, Yoshiyuki

    2016-01-01

    demonstrated that the two-gene dataset improved the accuracy of divergence time estimates. The P. obliquiloculata lineage diverged twice, first at the end of the Pliocene (3.1 Ma) and again in the middle Pleistocene (1.4 Ma). Both timings coincided with the environmental changes, which indirectly involved geographic separation of populations. The habitat of P. obliquiloculata was expanded toward the higher latitudinal zones during the stable warm periods and subsequently placed on the steep environmental gradients following the global cooling. Different environmental conditions in the stable warm tropics and unstable higher latitudes may have triggered ecological divergence among the populations, leading to adaptive differentiation and eventually speciation. A comprehensive analysis of divergence time estimates combined with phylogeography enabled us to reveal the evolutionary history of the pelagic plankton and to find the potential paleoenvironmental events, which could have changed their biogeography and ecology. PMID:26886349

  17. Evolution of a Planktonic Foraminifer during Environmental Changes in the Tropical Oceans.

    PubMed

    Ujiié, Yurika; Ishitani, Yoshiyuki

    2016-01-01

    demonstrated that the two-gene dataset improved the accuracy of divergence time estimates. The P. obliquiloculata lineage diverged twice, first at the end of the Pliocene (3.1 Ma) and again in the middle Pleistocene (1.4 Ma). Both timings coincided with the environmental changes, which indirectly involved geographic separation of populations. The habitat of P. obliquiloculata was expanded toward the higher latitudinal zones during the stable warm periods and subsequently placed on the steep environmental gradients following the global cooling. Different environmental conditions in the stable warm tropics and unstable higher latitudes may have triggered ecological divergence among the populations, leading to adaptive differentiation and eventually speciation. A comprehensive analysis of divergence time estimates combined with phylogeography enabled us to reveal the evolutionary history of the pelagic plankton and to find the potential paleoenvironmental events, which could have changed their biogeography and ecology.

  18. Modeling coastal environmental changes by fuzzy logic approach

    NASA Astrophysics Data System (ADS)

    Zoran, Maria A.; Zoran, Liviu Florin V.

    2004-10-01

    The coastal zone contains that unique environmental triple point where the water, land and atmospheric components of the terrestrial surface converge and interact. This paper is an application of remotely sensed images in marine coastal land cover classification for change detection assessment. The nature of the gradients in coastal region land cover composition among the map classes can therefore be identified.A supervised approach uses the prior knowledge about the area and thus it is very useful in getting better results than an unsupervised classification. The study test area was North-Western Black Sea coastal region, characterized by no so fast drastic changes,as it is a slow and continuous process. Satellite images (Landsat MSS, TM, ETM, SAR ERS, ASTER, MODIS) over a period of time between 1975 and 2003 were chosen for change detection analysis.In the fuzzy approach, it is possible to describe change as a degree, this being the main reason for fuzzy approach using for classification and change detection of major land cover classes in a marine coastal area.The results can be utilized as a temporal land-use change model for a region to quantify the extent and nature of change, and aid in future prediction studies, which helps in planning environmental agencies to develop sustainable land-use practices .

  19. Climate change and evolution: disentangling environmental and genetic responses.

    PubMed

    Gienapp, P; Teplitsky, C; Alho, J S; Mills, J A; Merilä, J

    2008-01-01

    Rapid climate change is likely to impose strong selection pressures on traits important for fitness, and therefore, microevolution in response to climate-mediated selection is potentially an important mechanism mitigating negative consequences of climate change. We reviewed the empirical evidence for recent microevolutionary responses to climate change in longitudinal studies emphasizing the following three perspectives emerging from the published data. First, although signatures of climate change are clearly visible in many ecological processes, similar examples of microevolutionary responses in literature are in fact very rare. Second, the quality of evidence for microevolutionary responses to climate change is far from satisfactory as the documented responses are often - if not typically - based on nongenetic data. We reinforce the view that it is as important to make the distinction between genetic (evolutionary) and phenotypic (includes a nongenetic, plastic component) responses clear, as it is to understand the relative roles of plasticity and genetics in adaptation to climate change. Third, in order to illustrate the difficulties and their potential ubiquity in detection of microevolution in response to natural selection, we reviewed the quantitative genetic studies on microevolutionary responses to natural selection in the context of long-term studies of vertebrates. The available evidence points to the overall conclusion that many responses perceived as adaptations to changing environmental conditions could be environmentally induced plastic responses rather than microevolutionary adaptations. Hence, clear-cut evidence indicating a significant role for evolutionary adaptation to ongoing climate warming is conspicuously scarce.

  20. Late Pleistocene eolian-alluvial interference in the Balearic Islands (Western Mediterranean)

    NASA Astrophysics Data System (ADS)

    Pomar, Francisco; Del Valle, Laura; Fornós, Joan J.; Gómez-Pujol, Lluís; Anechitei-Deacu, Valentina; Timar-Gabor, Alida

    2016-04-01

    This study deals with alluvial fan and aeolian sediments interference. Although initially they are two different environments, with different processes and resulting forms, very often their interaction produces deposits that share characteristics and features from both environments, as well as, maintain inherited elements from one to each other. In this sense, the aeolian-alluvial interference is the geomorphological expression of the coincidence, disruption and/or overlapping of aeolian and alluvial environments. Climate appears to be one of the most important controls on the role and magnitude of each environment in terms of sediment supply, precipitation, runoff or aeolian transport. In this study, eight major sedimentary facies have been described involving the succession of coastal, aeolian, colluvial and alluvial environments. Carbonate sandstones, breccias, conglomerates and fine-grained deposits are the main component of these sequences. OSL dating of aeolian levels indicate that their deposition took place during the Late Pleistocene, establishing a paleoclimatic evolution of Balearic coastal areas during the last 125 ka. The sedimentological and chronological analysis of these deposits allows reconstructing the coastal environmental changes during the Late Pleistocene at the Balearic archipelago. Keywords: Alluvial sedimentation, eolian sedimentation, alluvial-eolian interference, sea level, Late Pleistocene, Balearic Islands.

  1. Upper Pleistocene and Holocene lakes in the An Nafud, Saudi Arabia

    USGS Publications Warehouse

    Schulz, E.; Whitney, J.W.

    1986-01-01

    Two major lake periods were discovered in the sand sea of An Nafud and the surrounding areas. In Upper Pleistocene large lakes occurred around the dune area and in the interior of the sand sea. Their deposits were formed between 34 000 and 24 000 BP. The lakes were not conformous to the present dune relief. They had an extension of several km2 and a depth of ca. 10 m. Holocene lakes (8 400-5 400 BP) were of minor extension and restricted to the interdune depressions. Lake sediments consist of cemented sand, calcareous crusts and diatomites. Upper Pleistocene lakes were fresh water lakes, the Halocene lakes were mostly swamps depending on rising and falling aquifers in the dunes. Plant remains as pollen and macro rests show that the environmental changes didn't exceed the system of semidesert comparable to the modern plant cover. However, the Upper Pleistocene lake deposits contain some more soudanian elements as the Holocene sediments in the pollen spectra. Climatically the lake formations are interpreted as depending on a stronger influence of the mediterranean cyclones or an interaction of them with monsoonal air masses. ?? 1986 Dr W. Junk Publishers.

  2. Climate change and coastal environmental risk perceptions in Florida.

    PubMed

    Carlton, Stuart J; Jacobson, Susan K

    2013-11-30

    Understanding public perceptions of climate change risks is a prerequisite for effective climate communication and adaptation. Many studies of climate risk perceptions have either analyzed a general operationalization of climate change risk or employed a case-study approach of specific adaptive processes. This study takes a different approach, examining attitudes toward 17 specific, climate-related coastal risks and cognitive, affective, and risk-specific predictors of risk perception. A survey of 558 undergraduates revealed that risks to the physical environment were a greater concern than economic or biological risks. Perceptions of greater physical environment risks were significantly associated with having more pro-environmental attitudes, being female, and being more Democratic-leaning. Perceptions of greater economic risks were significantly associated with having more negative environmental attitudes, being female, and being more Republican-leaning. Perceptions of greater biological risks were significantly associated with more positive environmental attitudes. The findings suggest that focusing on physical environment risks maybe more salient to this audience than communications about general climate change adaptation. The results demonstrate that climate change beliefs and risk perceptions are multifactorial and complex and are shaped by individuals' attitudes and basic beliefs. Climate risk communications need to apply this knowledge to better target cognitive and affective processes of specific audiences, rather than providing simple characterizations of risks.

  3. Causes of Climate and Environmental Changes: The Need for Environmental-Friendly Education Policy in Nigeria

    ERIC Educational Resources Information Center

    Nwankwoala, H. N. L.

    2015-01-01

    Man cannot naturally be detached from his environment. From time to time, changes in climate and environmental conditions occur as a result of natural and human factors. Obviously, the natural factors are almost beyond human control. But, the human factors are to a very large extent under human control. Thus, this paper tried to discover natural…

  4. EDITORIAL: Integrated assessments of environmental change on the Tibetan Plateau Integrated assessments of environmental change on the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Sheng, Yongwei; Yao, Tandong

    2009-12-01

    The Tibetan Plateau is one of the Earth's most sensitive regions in responding to climate change due to its extremely high altitude and the presence of permafrost and glaciers. The cryosphere, biosphere and hydrosphere of the plateau have been undergoing significant changes. Due to the low human population density, environmental changes on the plateau are largely driven by natural processes. Thus, the plateau provides a unique and comprehensive site for global change studies. This focus issue on Climate Change on the Tibetan Plateau aims to address both paleo and recent environmental changes across the plateau to facilitate our understanding of this remote and under-studied area. We invited a wide spectrum of contributions to address climate change, permafrost degradation, glacier/snow/ice dynamics, lake dynamics, land- cover/land-use changes, and their interactions on the plateau. Collectively, the diverse contributions in this special issue are expected to present the recent advancement of the above topics and beyond. See the PDF for the full text of the editorial. Focus on Climate Change on the Tibetan Plateau Contents Does a weekend effect in diurnal temperature range exist in the eastern and central Tibetan Plateau? Qinglong You, Shichang Kang, Wolfgang-Albert Flügel, Arturo Sanchez-Lorenzo, Yuping Yan, Yanwei Xu and Jie Huang Diurnal variations of summertime precipitation over the Tibetan Plateau in relation to orographically-induced regional circulations Xiaodong Liu, Aijuan Bai and Changhai Liu Lake-level fluctuations since the Last Glaciation in Selin Co (lake), Central Tibet, investigated using optically stimulated luminescence dating of beach ridges Dewen Li, Yingkui Li, Baoqi Ma, Guocheng Dong, Liqiang Wang and Junxiang Zhao Recent changes in Imja Glacial Lake and its damming moraine in the Nepal Himalaya revealed by in situ surveys and multi-temporal ASTER imagery Koji Fujita, Akiko Sakai, Takayuki Nuimura, Satoru Yamaguchi and Rishi R Sharma Changes

  5. First ancient DNA sequences from the Late Pleistocene red deer (Cervus elaphus) in the Crimea, Ukraine

    NASA Astrophysics Data System (ADS)

    Stanković, Ana; Nadachowski, Adam; Doan, Karolina; Stefaniak, Krzysztof; Baca, Mateusz; Socha, Paweł; Wegleński, Piotr; Ridush, Bogdan

    2010-05-01

    The Late Pleistocene has been a period of significant population and species turnover and extinctions among the large mammal fauna. Massive climatic and environmental changes during Pleistocene significantly influenced the distribution and also genetic diversity of plants and animals. The model of glacial refugia and habitat contraction to southern peninsulas in Europe as areas for the survival of temperate animal species during unfavourable Pleistocene glaciations is at present widely accepted. However, both molecular data and the fossil record indicate the presence of northern and perhaps north-eastern refugia in Europe. In recent years, much new palaeontological data have been obtained in the Crimean Peninsula, Ukraine, following extensive investigations. The red deer (Cervus elaphus) samples for aDNA studies were collected in Emine-Bair-Khosar Cave, situated on the north edge of Lower Plateau of the Chatyrdag Massif (Crimean Mountains). The cave is a vertical shaft, which functioned as a huge mega-trap over a long period of time (probably most of the Pleistocene). The bone assemblages provided about 5000 bones belonging to more than 40 species. The C. elaphus bones were collected from three different stratigraphical levels, radiocarbon dated by accelerator mass spectrometry (AMS) method. The bone fragments of four specimens of red deer were used for the DNA isolation and analysis. The mtDNA (Cytochome b) was successfully isolated from three bone fragments and the cytochrome b sequences were amplified by multiplex PCR. The sequences obtained so far allowed for the reconstruction of only preliminary phylogenetic trees. A fragment of metatarsus from level dated to ca. 48,500±2,000 years BP, yielded a sequence of 513 bp, allowing to locate the specimen on the phylogenetic tree within modern C. elaphus specimens from southern and middle Europe. The second bone fragment, a fragment of mandible, collected from level dated approximately to ca. 33,500±400 years BP

  6. Rethinking Environmental Protection: Meeting the Challenges of a Changing World

    PubMed Central

    Burke, Thomas A.; Cascio, Wayne E.; Costa, Daniel L.; Deener, Kacee; Fontaine, Thomas D.; Fulk, Florence A.; Jackson, Laura E.; Munns, Wayne R.; Orme-Zavaleta, Jennifer; Slimak, Michael W.; Zartarian, Valerie G.

    2017-01-01

    Summary: From climate change to hydraulic fracturing, and from drinking water safety to wildfires, environmental challenges are changing. The United States has made substantial environmental protection progress based on media-specific and single pollutant risk-based frameworks. However, today’s environmental problems are increasingly complex and new scientific approaches and tools are needed to achieve sustainable solutions to protect the environment and public health. In this article, we present examples of today’s environmental challenges and offer an integrated systems approach to address them. We provide a strategic framework and recommendations for advancing the application of science for protecting the environment and public health. We posit that addressing 21st century challenges requires transdisciplinary and systems approaches, new data sources, and stakeholder partnerships. To address these challenges, we outline a process driven by problem formulation with the following steps: a) formulate the problem holistically, b) gather and synthesize diverse information, c) develop and assess options, and d) implement sustainable solutions. This process will require new skills and education in systems science, with an emphasis on science translation. A systems-based approach can transcend media- and receptor-specific bounds, integrate diverse information, and recognize the inextricable link between ecology and human health. PMID:28248180

  7. Some biological consequences of environmental change: a study using barnacles (Cirripedia: Balanomorpha) and gum trees (Angiospermae: Myrtaceae).

    PubMed

    Buckeridge, John S

    2010-06-01

    Uniformitarianism permits understanding of the past on the basis of the present, and modeling the future through consideration of the fossil record. The present paper addresses the impact environmental (climatic) change has had on acorn barnacles and eucalyptus trees. Acorn barnacles (Balanomorpha) are first recorded after the K/T mass-extinction event. In the Paleogene, rapid radiation resulted in their occupying most marine environments. That balanomorphs survived both the Paleocene-Eocene thermal maximum and the Pleistocene glaciation is testament to their ability to adapt to opportunities; they are known from the littoral (Chamaesipho) to depths of 3600 m (Tetrachaelasma) and within this from diverse substrates: rock, wood and miscellaneous flotsam, plus in symbiosis or commensalism with most larger marine organisms. Darwin's (1854) view of the late Tertiary as the age of barnacles is reflected in their diversity, distribution and biomass. Barnacles are contrasted with the Australian Myrtaceae: plants ranging from woody shrubs to tall trees. The most significant is Eucalyptus sensu lato, which typifies Australia's flora, and is characterized by aromatic leaves that produce eucalyptol. Eucalyptus has evolved strategies that result in its domination of Australian open woodlands: these include production of highly flammable eucalyptol oil (with a flashpoint of 49 °C) and an unprecedented ability to regenerate following forest fires. Gum trees and barnacles first appear in the Paleogene, their earliest records are Australasian, and they both demonstrate extraordinary resilience when environmental conditions are optimal.

  8. Middle Pleistocene Climate Change Recorded in Fossil Mammal Teeth from Tarija, Bolivia, and Upper Limit of the Ensenadan Land-Mammal Age

    NASA Astrophysics Data System (ADS)

    MacFadden, Bruce J.

    2000-07-01

    Fossiliferous middle Pleistocene sediments of the Tarija basin of southern Bolivia contain a classic Ensenadan land-mammal fauna. New carbon isotopic data reported here for 50 specimens of the grazing mammals Equus (horse) and Cuvieronius (mastodon), documented from eight stratigraphic levels at Tarija, vary significantly in the δ13C values of their teeth. The pattern of variation appears to reflect the proportion of C3 and C4 grasses eaten during colder (more C3) and warmer (more C4) times. Within age limits set by associated magnetostratigraphy, the cold periods can be correlated with particular even-numbered stages in the marine oxygen-isotope record, and the warm periods can be correlated with odd-numbered stages. The oldest fossil teeth analyzed from the Tarija section can thereby be assigned to stage 29, and the youngest to stages 17 or 15, that is; the teeth range in age from about 1.1 myr to as young as 0.7 myr. Based on correlation of the upper part of the Tarija beds to the isotopic stages, the upper limit of the Ensenadan land-mammal age is between 0.7 and 0.6 myr, which is younger than stated in most previous studies.

  9. Integrated Decision Support for Global Environmental Change Adaptation

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Cantrell, S.; Higgins, G. J.; Marshall, J.; VanWijngaarden, F.

    2011-12-01

    Environmental changes are happening now that has caused concern in many parts of the world; particularly vulnerable are the countries and communities with limited resources and with natural environments that are more susceptible to climate change impacts. Global leaders are concerned about the observed phenomena and events such as Amazon deforestation, shifting monsoon patterns affecting agriculture in the mountain slopes of Peru, floods in Pakistan, water shortages in Middle East, droughts impacting water supplies and wildlife migration in Africa, and sea level rise impacts on low lying coastal communities in Bangladesh. These environmental changes are likely to get exacerbated as the temperatures rise, the weather and climate patterns change, and sea level rise continues. Large populations and billions of dollars of infrastructure could be affected. At Northrop Grumman, we have developed an integrated decision support framework for providing necessary information to stakeholders and planners to adapt to the impacts of climate variability and change at the regional and local levels. This integrated approach takes into account assimilation and exploitation of large and disparate weather and climate data sets, regional downscaling (dynamic and statistical), uncertainty quantification and reduction, and a synthesis of scientific data with demographic and economic data to generate actionable information for the stakeholders and decision makers. Utilizing a flexible service oriented architecture and state-of-the-art visualization techniques, this information can be delivered via tailored GIS portals to meet diverse set of user needs and expectations. This integrated approach can be applied to regional and local risk assessments, predictions and decadal projections, and proactive adaptation planning for vulnerable communities. In this paper we will describe this comprehensive decision support approach with selected applications and case studies to illustrate how this

  10. The emergence of land change science for global environmental change and sustainability

    PubMed Central

    Turner, B. L.; Lambin, Eric F.; Reenberg, Anette

    2007-01-01

    Land change science has emerged as a fundamental component of global environmental change and sustainability research. This interdisciplinary field seeks to understand the dynamics of land cover and land use as a coupled human–environment system to address theory, concepts, models, and applications relevant to environmental and societal problems, including the intersection of the two. The major components and advances in land change are addressed: observation and monitoring; understanding the coupled system—causes, impacts, and consequences; modeling; and synthesis issues. The six articles of the special feature are introduced and situated within these components of study. PMID:18093934

  11. Environmental Change Detection Using Multi-Temporal SAR Imagery

    NASA Astrophysics Data System (ADS)

    Fazel, Mohammad A.; Homayouni, Saeid; Aghakarimi, Armin

    2013-04-01

    Monitoring of environmental phenomena in short-, mid- and long-term periods is the first step of any study or plan for natural resource management. As a result, detection and identification of the environmental changes became a main area of research for different applications. Remotely sensed data and especially Synthetic Aperture Radar (SAR) imagery thanks to its independence to weather conditions and sun illumination, and its spatial and temporal resolution ability is a valuable source of information for change detection analysis and provides reliable data for information extraction for various applications. In general, change detection methods are grouped into supervised and unsupervised methods. Supervised methods work based on multi-temporal land-cover mapping of satellite images. While, unsupervised techniques include the very simple idea of image differencing to more sophisticated statistical modeling of changes in images. Unsupervised methods because of their advantages are more important in many applications. In recent years, the use of kernel based methods in change detection applications became an interesting topic in remote sensing community. Kernel-based methods and machine learning algorithms are the unsupervised paradigms which introduced powerful tools to deal with nonlinear classification. In this paper, we have presented a fully unsupervised framework for detecting the Urmia Lake changes during 2007 to 2010. This method uses the kernel-based clustering technique. The kernel k-means algorithm separates the changes from no-change classes of speckle free images. This method is a non-linear algorithm which considers the contextual information. For this purpose, at first, difference maps are calculated from multi-temporal data. Then these maps are projected into a higher dimensional space by using kernel function. Finally an unsupervised k-means clustering algorithm is used to obtain change and no-change classes. The proposed methodology is applied to

  12. Proteome Analysis of Borrelia burgdorferi Response to Environmental Change

    SciTech Connect

    Angel, Thomas E.; Luft, Benjamin J.; Yang, Xiaohua; Nicora, Carrie D.; Camp, David G.; Jacobs, Jon M.; Smith, Richard D.

    2010-11-02

    We examined global changes in protein expression in the B31 strain of Borrelia burgdorferi, in response to two environmental cues (pH and temperature) chosen for their reported similarity to those encountered at different stages of the organism’s life cycle. Multidimensional nano-liquid chromatographic separations coupled with tandem mass spectrometry were used to examine the array of proteins (i.e., the proteome) of B. burgdorferi for different pH and temperature culture conditions. Changes in pH and temperature elicited in vitro adaptations of this spirochete known to cause Lyme disease and led to alterations in protein expression that are associated with increased microbial pathogenesis. We identified 1031 proteins that represent 59% of the annotated genome of B. burgdorferi and elucidated a core proteome of 414 proteins that were present in all environmental conditions investigated. Observed changes in protein abundances indicated varied replicon usage, as well as proteome functional distributions between the in vitro cell culture conditions. Surprisingly, the pH and temperature conditions that mimicked B. burgdorferi residing in the gut of a fed tick showed a marked reduction in protein diversity. Additionally, the results provide us with leading candidates for exploring how B. burgdorferi adapts to and is able to survive in a wide variety of environmental conditions and lay a foundation for planned in situ studies of B. burgdorferi isolated from the tick midgut and infected animals.

  13. Using oligochaeta assemblages as an indicator of environmental changes.

    PubMed

    Behrend, R D L; Takeda, A M; Gomes, L C; Fernandes, S E P

    2012-11-01

    We designed a field survey (the entire river length; not dammed: First and Second plateaus; dammed: Third Plateau) to test the hypothesis that the cascade of reservoirs promoted a reduction in species richness and changed the composition of Oligochaeta assemblage along the Iguaçu River. Changes in environmental variables and in richness and composition of Oligochaeta were summarized by Canonic Correspondence Analysis. Along the Iguaçu River, conductivity, and altitude decreased, whereas temperature increased. Oligochaeta composition showed a significant spatial variation, with higher abundances of the family Tubificidae and the genus Dero (Naididae) occurring in the First Plateau. In the Second and Third plateaus, few species were dominant, with increases in the presence of species of Naididae below dams. We found a clear decrease in species richness along the Iguaçu River. Moreover, we found that Oligochaeta assemblage was influenced by some environmental variables such as altitude, conductivity, substrate type and temperature, and by anthropogenic activities (human occupation and damming). The results supported the use of Oligochaeta as surrogate taxa to predict environmental changes along impacted (dammed and eutrophic) rivers. The validity of this was indicated by the strong and significant gradient registered, from the headwater to mouth of the Iguaçu River.

  14. USGS Environmental health science strategy: providing environmental health science for a changing world: public review release

    USGS Publications Warehouse

    Bright, Patricia R.; Buxton, Herbert T.; Balistrieri, Laurie S.; Barber, Larry B.; Chapelle, Francis H.; Cross, Paul C.; Krabbenhoft, David P.; Plumlee, Geoffrey S.; Sleeman, Jonathan M.; Tillitt, Donald E.; Toccalino, Patricia L.; Winton, James R.

    2012-01-01

    America has an abundance of natural resources. We have bountiful clean water, fertile soil, and unrivaled national parks, wildlife refuges, and public lands. These resources enrich our lives and preserve our health and wellbeing. These resources have been maintained because of our history of respect for their value and an enduring commitment to their vigilant protection. Awareness of the social, economic, and personal value of the health of our environment is increasing. The emergence of environmentally driven diseases caused by environmental exposure to contaminants and pathogens is a growing concern worldwide. New health threats and patterns of established threats are affected by both natural and anthropogenic changes to the environment. Human activities are key drivers of emerging (new and re-emerging) health threats. Societal demands for land and natural resources, a better quality of life, improved economic prosperity, and the environmental impacts associated with these demands will continue to increase. Natural earth processes, climate trends, and related climatic events will add to the environmental impact of human activities. These environmental drivers will influence exposure to disease agents, including viral, bacterial, prion, and fungal pathogens, parasites, natural earth materials, toxins and other biogenic compounds, and synthetic chemicals and substances. The U.S. Geological Survey (USGS) defines environmental health science broadly as the interdisciplinary study of relations among the quality of the physical environment, the health of the living environment, and human health. The interactions among these three spheres are driven by human activities, ecological processes, and natural earth processes; the interactions affect exposure to contaminants and pathogens and the severity of environmentally driven diseases in animals and people. This definition provides USGS with a framework for synthesizing natural science information from across the Bureau

  15. Palaeogeography of the Caspian Sea marine Pleistocene

    NASA Astrophysics Data System (ADS)

    Yanina, Tamara; Svitoch, Aleksander; Makshaev, Radik; Khomchenko, Denis

    2016-04-01

    Vertical succession of the fossil molluscs of Didacna genus along the Pleistocene sequence of the Caspian Sea area allows for detailed subdivision of the sediments. Zone, i.e. the Caspian Sea Pleistocene, is the highest stratigraphical unit of the regional Quaternary stratigraphic scale. It corresponds to the biozone of Didacna Eichwald subgenus. Based on the fossil groups of Didacna molluscs, the deposits are subdivided into the Baku, Urundzhik-Singil', lower and upper Khazarian, Khvalinian, and post-Khvalinian horizons. Further subdision is based on the changes in Didacna assemblages. Three big transgressive epochs are distinguished in the Pleistocene history of the Caspian Sea that were separated by deep and long regressions. These are the Baku, early Khazarian and Khvalinian transgressions. In transgressive sea basins, the sea level reached the height of 40-50 m and was regulated by the outflow of the Caspian waters into the Black Sea via the Manych depression. The areas of transgressive basins were similar. At the Caucasian coast, the extent of the Baku and early Khazarian transgressions exceeded that of the Khvalinian transgression, while in the Northern Caspian Sea Region the latter was slightly more extensive than the preceding ones. The Urundzhik, late Khazarian and New Caspian transgressions represented sea-level rise of lower rank. All of them were recorded within big regressive epochs being usually related to warm (interglacial) climatic conditions: Singil' (Likhvin), Mikulino and Holocene, respectively. Like at present, the Pleistocene Caspian Sea represented a self-regulating system. Maximal extent of ancient sea basins was dependent upon the height of the Manych sill (that was the main regulating factor), the amount of precipitation, river runoff, and decrease in evaporation. Minimal extent of the sea basin was dependent upon the area and capacity of its southern and middle depressions. At the same time, the rest states (extents) of the Caspian Sea

  16. Moving past framing climate change as an environmental issue (Invited)

    NASA Astrophysics Data System (ADS)

    Ebi, K. L.

    2013-12-01

    Continuing to frame climate change as an environmental issue can limit understanding by decision-makers and the public of the magnitude of the challenges faced by human and natural systems as the climate continues to change. Environmental issues are typically researched and managed using methods and tools that have been effective in dealing with other environmental concerns, from tropospheric ozone to lead exposure. Risk assessment is a commonly used approach to understanding the risk(s) posed by an agent, with four basic steps: (1) hazard identification; (2) dose-response assessment; (3) exposure assessment; and (4) risk characterization. This framing does not fully capture the complex interrelationships and feedbacks that often characterize the risks of climate change; understanding these can lead to better-informed decisions. Challenges with using traditional risk assessment to understand the health risks of climate change, for example, include the 'exposure' can range from increases in the mean and/or variance of temperature, precipitation, and other weather variables, to ocean acidification. Each is associated with a range of adverse health outcomes, with many associations indirect and/or nonlinear. Further, uncertainty about the magnitude, timing, and nature of changes in the climate system results in a need to estimate the potential impacts under a range of possible scenarios. In addition, most climate-sensitive health outcomes have multiple, contributing causes that may be interrelated, making it difficult to single out the influence of climate change against a backdrop of other risk factors, including socioeconomic factors, that also will change over time. In short, the primary assumption underlying traditional risk assessment -- that a defined exposure to a specific agent causes an adverse health outcome to identifiable exposed populations -- does not apply to climate change. Climate literacy can be improved by moving the framing from a relatively linear

  17. Multidecadal Fluvial Sediment Fluxes to Deltas under Environmental Change Scenarios

    NASA Astrophysics Data System (ADS)

    Dunn, Frances; Darby, Stephen; Nicholls, Robert

    2016-04-01

    Sediment delivery is vital to sustain delta environments on which over half a billion people live worldwide. Due to factors such as subsidence and sea level rise, deltas sink relative to sea level if sediment is not delivered to and retained on their surfaces. Deltas which sink relative to sea level experience flooding, land degradation and loss, which endangers anthropogenic activities and populations. The future of fluvial sediment fluxes, a key mechanism for sediment delivery to deltas, is uncertain due to complex environmental changes which are predicted to occur over the coming decades. This research investigates fluvial sediment fluxes under environmental changes in order to assess the sustainability of delta environments under potential future scenarios up to 2100. Global datasets of climate change, reservoir construction, and population and GDP as proxies for anthropogenic influence through land use changes are used to drive the catchment numerical model WBMsed, which is being used to investigate the effects of these environmental changes on fluvial sediment delivery. This process produces fluvial sediment fluxes under multiple future scenarios which will be used to assess the future sustainability of a selection of 8 vulnerable deltas, although the approach can be applied to deltas worldwide. By modelling potential future scenarios of fluvial sediment flux, this research contributes to the prognosis for delta environments. The future scenarios will inform management at multiple temporal scales, and indicate the potential consequences for deltas of various anthropogenic activities. This research will both forewarn managers of potentially unsustainable deltas and indicate those anthropogenic activities which encourage or hinder the creation of sustainable delta environments.

  18. PALEOECOLOGY. Abrupt warming events drove Late Pleistocene Holarctic megafaunal turnover.

    PubMed

    Cooper, Alan; Turney, Chris; Hughen, Konrad A; Brook, Barry W; McDonald, H Gregory; Bradshaw, Corey J A

    2015-08-07

    The mechanisms of Late Pleistocene megafauna extinctions remain fiercely contested, with human impact or climate change cited as principal drivers. We compared ancient DNA and radiocarbon data from 31 detailed time series of regional megafaunal extinctions and replacements over the past 56,000 years with standard and new combined records of Northern Hemisphere climate in the Late Pleistocene. Unexpectedly, rapid climate changes associated with interstadial warming events are strongly associated with the regional replacement or extinction of major genetic clades or species of megafauna. The presence of many cryptic biotic transitions before the Pleistocene/Holocene boundary revealed by ancient DNA confirms the importance of climate change in megafaunal population extinctions and suggests that metapopulation structures necessary to survive such repeated and rapid climatic shifts were susceptible to human impacts.

  19. Host manipulation in the face of environmental changes: Ecological consequences

    PubMed Central

    Labaude, Sophie; Rigaud, Thierry; Cézilly, Frank

    2015-01-01

    Several parasite species, particularly those having complex life-cycles, are known to induce phenotypic alterations in their hosts. Most often, such alterations appear to increase the fitness of the parasites at the expense of that of their hosts, a phenomenon known as “host manipulation”. Host manipulation can have important consequences, ranging from host population dynamics to ecosystem engineering. So far, the importance of environmental changes for host manipulation has received little attention. However, because manipulative parasites are embedded in complex systems, with many interacting components, changes in the environment are likely to affect those systems in various ways. Here, after reviewing the ecological importance of manipulative parasites, we consider potential causes and consequences of changes in host manipulation by parasites driven by environmental modifications. We show that such consequences can extend to trophic networks and population dynamics within communities, and alter the ecological role of manipulative parasites such as their ecosystem engineering. We suggest that taking them into account could improve the accuracy of predictions regarding the effects of global change. We also propose several directions for future studies. PMID:26835252

  20. Mercury enrichment indicates volcanic triggering of Valanginian environmental change

    PubMed Central

    Charbonnier, Guillaume; Morales, Chloé; Duchamp-Alphonse, Stéphanie; Westermann, Stéphane; Adatte, Thierry; Föllmi, Karl B.

    2017-01-01

    The Valanginian stage (Early Cretaceous) includes an episode of significant environmental changes, which are well defined by a positive δ13C excursion. This globally recorded excursion indicates important perturbations in the carbon cycle, which has tentatively been associated with a pulse in volcanic activity and the formation of the Paraná-Etendeka large igneous province (LIP). Uncertainties in existing age models preclude, however, its positive identification as a trigger of Valanginian environmental changes. Here we report that in Valanginian sediments recovered from a drill core in Wąwał (Polish Basin, Poland), and from outcrops in the Breggia Gorge (Lombardian Basin, southern Switzerland), and Orpierre and Angles (Vocontian Basin, SE France), intervals at or near the onset of the positive δ13C excursion are significantly enriched in mercury (Hg). The persistence of the Hg anomaly in Hg/TOC, Hg/phyllosilicate, and Hg/Fe ratios shows that organic-matter scavenging and/or adsorbtion onto clay minerals or hydrous iron oxides only played a limited role. Volcanic outgassing was most probably the primary source of the Hg enrichments, which demonstrate that an important magmatic pulse triggered the Valanginian environmental perturbations. PMID:28106091

  1. Late Holocene Environmental Changes from NY-NJ Estuaries

    NASA Technical Reports Server (NTRS)

    Peteet, Dorothy M.

    2000-01-01

    High-resolution records of environmental change in the lower Hudson estuary are quite rare. We present preliminary data from several marshes in the New York- New Jersey region in order to understand the late Holocene environmental history of this region. Our project includes salt marsh cores from Hackensack, Piermont, Staten Island, and Jamaica Bay. Our preliminary research has focused on a 11.15 m sediment core from Piermont Marsh, New York (40 deg N, 74 deg W) in an attempt to document the Holocene environmental history of the region. Lithology, loss -on -ignition (LOI), pollen, plant macrofossils, charcoal, and foraminifera were analyzed. Core lithology consists of peat, silts, and clays that vary in color and texture. The base of the core is AMS C-14 dated to 4190 yr BP. Preliminary low-resolution analysis of the core to date includes sampling at the 1-meter interval throughout the core. LOI of the sediments ranges from 1% to 85%. Average rate of deposition is about .26 cm/yr. Major changes in pollen percentages are visible throughout the core.

  2. Late Holocene Environmental Changes from NY-NJ Estuaries

    NASA Technical Reports Server (NTRS)

    Peteet, Dorothy M.; Wong, Jennifer K.

    2000-01-01

    High-resolution records of environmental change in the lower Hudson estuary are quite rare. We present preliminary data from several marshes in the New York- New Jersey region in order to understand the late Holocene environmental history of this region. Our project includes salt marsh cores from Hackensack, Piermont, Staten Island, and Jamaica Bay. Our preliminary research has focused on a 11.15 m. sediment core from Piermont Marsh, New York (40 N, 74 W) in an attempt to document the Holocene environmental history of the region. Lithology, loss-on-ignition (LOI), pollen, plant macrofossils, charcoal, and foraminifera were analyzed. Core lithology consists of peat, silts, and clays that vary in color and texture. The base of the core is AMS C-14 dated to 4190 yr BP. Preliminary low-resolution analysis of the core to date includes sampling at the 1-meter interval throughout the core. LOI of the sediments ranges from 1% to 85%. Average rate of deposition is about .26 cm/yr. Major changes in pollen percentages are visible throughout the core.

  3. Mercury enrichment indicates volcanic triggering of Valanginian environmental change.

    PubMed

    Charbonnier, Guillaume; Morales, Chloé; Duchamp-Alphonse, Stéphanie; Westermann, Stéphane; Adatte, Thierry; Föllmi, Karl B

    2017-01-20

    The Valanginian stage (Early Cretaceous) includes an episode of significant environmental changes, which are well defined by a positive δ(13)C excursion. This globally recorded excursion indicates important perturbations in the carbon cycle, which has tentatively been associated with a pulse in volcanic activity and the formation of the Paraná-Etendeka large igneous province (LIP). Uncertainties in existing age models preclude, however, its positive identification as a trigger of Valanginian environmental changes. Here we report that in Valanginian sediments recovered from a drill core in Wąwał (Polish Basin, Poland), and from outcrops in the Breggia Gorge (Lombardian Basin, southern Switzerland), and Orpierre and Angles (Vocontian Basin, SE France), intervals at or near the onset of the positive δ(13)C excursion are significantly enriched in mercury (Hg). The persistence of the Hg anomaly in Hg/TOC, Hg/phyllosilicate, and Hg/Fe ratios shows that organic-matter scavenging and/or adsorbtion onto clay minerals or hydrous iron oxides only played a limited role. Volcanic outgassing was most probably the primary source of the Hg enrichments, which demonstrate that an important magmatic pulse triggered the Valanginian environmental perturbations.

  4. Mercury enrichment indicates volcanic triggering of Valanginian environmental change

    NASA Astrophysics Data System (ADS)

    Charbonnier, Guillaume; Morales, Chloé; Duchamp-Alphonse, Stéphanie; Westermann, Stéphane; Adatte, Thierry; Föllmi, Karl B.

    2017-01-01

    The Valanginian stage (Early Cretaceous) includes an episode of significant environmental changes, which are well defined by a positive δ13C excursion. This globally recorded excursion indicates important perturbations in the carbon cycle, which has tentatively been associated with a pulse in volcanic activity and the formation of the Paraná-Etendeka large igneous province (LIP). Uncertainties in existing age models preclude, however, its positive identification as a trigger of Valanginian environmental changes. Here we report that in Valanginian sediments recovered from a drill core in Wąwał (Polish Basin, Poland), and from outcrops in the Breggia Gorge (Lombardian Basin, southern Switzerland), and Orpierre and Angles (Vocontian Basin, SE France), intervals at or near the onset of the positive δ13C excursion are significantly enriched in mercury (Hg). The persistence of the Hg anomaly in Hg/TOC, Hg/phyllosilicate, and Hg/Fe ratios shows that organic-matter scavenging and/or adsorbtion onto clay minerals or hydrous iron oxides only played a limited role. Volcanic outgassing was most probably the primary source of the Hg enrichments, which demonstrate that an important magmatic pulse triggered the Valanginian environmental perturbations.

  5. Benthic foraminifera and environmental changes in Long Island Sound

    USGS Publications Warehouse

    Thomas, E.; Gapotchenko, T.; Varekamp, J.C.; Mecray, E.I.; Buchholtz ten Brink, M. R.

    2000-01-01

    Benthic foraminiferal faunas in Long Island Sound (LIS) in the 1940s and 1960s were of low diversity, and dominated by species of the genus Elphidium, mainly Elphidium excavatum clavatum, with common Buccella frigida and Eggerella advena. The distribution of these species was dominantly correlated with depth, but it was not clear which depth-related environmental variable was most important. Differences between faunas collected in 1996 and 1997, and in the 1940s and 1960s include a strong decrease in relative abundance of Eggerella advena over all LIS, an increase in relative abundance of Ammonia beccarii in western LIS, and a decrease in species diversity. The decreased diversity suggests that environmental stress caused the faunal changes. Oxygen isotope data for E. excavatum clavatum indicate that a change in salinity is not a probable cause. Carbon isotope data suggest that the supply of organic matter to the benthos increased since the early 1960s, with a stronger increase in western LIS where algal blooms have occurred since the early 1970s, possibly as a result of nutrient input by waste water treatment plants. These blooms or the resulting episodes of anoxia/hypoxia may have played a role in the increased relative abundance of A. beccarii. There is no clear explanation for the decreased abundance of E. advena, but changes in the phytoplankton composition (thus food supply) are a possible cause. Benthic foraminiferal faunal and stable isotope data have excellent potential as indicators of physicochemical environmental changes and their effects on the biota in LIS.

  6. Improved data for integrated modeling of global environmental change

    NASA Astrophysics Data System (ADS)

    Lotze-Campen, Hermann

    2011-12-01

    The assessment of global environmental changes, their impact on human societies, and possible management options requires large-scale, integrated modeling efforts. These models have to link biophysical with socio-economic processes, and they have to take spatial heterogeneity of environmental conditions into account. Land use change and freshwater use are two key research areas where spatial aggregation and the use of regional average numbers may lead to biased results. Useful insights can only be obtained if processes like economic globalization can be consistently linked to local environmental conditions and resource constraints (Lambin and Meyfroidt 2011). Spatially explicit modeling of environmental changes at the global scale has a long tradition in the natural sciences (Woodward et al 1995, Alcamo et al 1996, Leemans et al 1996). Socio-economic models with comparable spatial detail, e.g. on grid-based land use change, are much less common (Heistermann et al 2006), but are increasingly being developed (Popp et al 2011, Schneider et al 2011). Spatially explicit models require spatially explicit input data, which often constrains their development and application at the global scale. The amount and quality of available data on environmental conditions is growing fast—primarily due to improved earth observation methods. Moreover, systematic efforts for collecting and linking these data across sectors are on the way (www.earthobservations.org). This has, among others, also helped to provide consistent databases on different land cover and land use types (Erb et al 2007). However, spatially explicit data on specific anthropogenic driving forces of global environmental change are still scarce—also because these cannot be collected with satellites or other devices. The basic data on socio-economic driving forces, i.e. population density and wealth (measured as gross domestic product per capita), have been prepared for spatially explicit analyses (CIESIN, IFPRI

  7. Spatial and temporal patterns of Pleistocene biogenic sediment accumulation in the Gulf of Alaska

    NASA Astrophysics Data System (ADS)

    Moy, C. M.; Bahlburg, H.; Childress, L. B.; Cowan, E. A.; Forwick, M.; Müller, J.; Ribeiro, F.; Ridgway, K. D.; Mix, A. C.

    2013-12-01

    Reconstructing the timing and nature of past changes in aquatic productivity in the Gulf of Alaska (GoA) can shed light on the primary processes driving biogeochemical cycling over geologic timescales. Today, Fe is an important micronutrient that limits primary productivity in surface waters beyond the continental shelf in much of the GoA. However, we have a relatively poor understanding of how Fe-delivery processes, combined with changing climate, environmental, and oceanographic conditions, interact to influence primary production over glacial-interglacial timescales. An important first step is to identify the spatial and temporal patterns of increased productivity in the sediment record. Here, we present sedimentologic and physical property data from IODP Expedition 341 and identify intervals where diatom ooze and diatom-rich mud lithofacies are prevalent during the Pleistocene. Among the Expedition 341 recovered cores, were high-recovery intervals in the outer (Site U1417) and inner (U1418) Surveyor Fan, and from a small slope basin at the edge of the continental shelf (Site U1419). In general, greenish gray diatomaceous ooze (containing >50 % diatoms in smear slides) and diatom-rich mud (>25% diatoms) is found in beds ranging in thickness from 20 to 150 cm, interbedded with gray mud that commonly contains lonestones. Ooze is occasionally found immediately overlying volcanic ash. Compared to non-biogenic mud, diatomaceous sediments are generally characterized by lower magnetic susceptibility, natural gamma ray, bulk density, and higher b* color reflectance. At Site U1417, we observe a frequent occurrence of diatomaceous ooze during the middle Pleistocene relative to the early and late Pleistocene. At Site U1418, intervals containing diatom ooze are less common than at U1417 and biogenic sediments are mainly observed within the late Pleistocene portion of the record. However, higher sedimentation rates at U1418 relative to U1417, and the co-occurrence of sand

  8. Environmental context change affects memory for performed actions.

    PubMed

    Sahakyan, Lili

    2010-03-01

    The current study investigated the effect of environmental context change between the study and test on the recall of action phrases that either were performed during encoding (subject-performed tasks, SPTs) or were verbally encoded (verbal tasks, VTs). Both SPTs and VTs showed the same magnitude of impaired recall when the study and test contexts mismatched. Furthermore, changing the context between the two study lists reduced cross-list intrusion errors compared to encoding the lists in the same context. Both SPTs and VTs benefited from studying the lists in different contexts as evidenced by reduced intrusions. Taken together, the results suggest that SPTs are integrated with their context because they suffered when context changed between the study and test, and they also benefited when they were performed in two environments versus the same environment.

  9. Avoiding climate change uncertainties in Strategic Environmental Assessment

    SciTech Connect

    Larsen, Sanne Vammen; Kørnøv, Lone; Driscoll, Patrick

    2013-11-15

    This article is concerned with how Strategic Environmental Assessment (SEA) practice handles climate change uncertainties within the Danish planning system. First, a hypothetical model is set up for how uncertainty is handled and not handled in decision-making. The model incorporates the strategies ‘reduction’ and ‘resilience’, ‘denying’, ‘ignoring’ and ‘postponing’. Second, 151 Danish SEAs are analysed with a focus on the extent to which climate change uncertainties are acknowledged and presented, and the empirical findings are discussed in relation to the model. The findings indicate that despite incentives to do so, climate change uncertainties were systematically avoided or downplayed in all but 5 of the 151 SEAs that were reviewed. Finally, two possible explanatory mechanisms are proposed to explain this: conflict avoidance and a need to quantify uncertainty.

  10. Ecosystem Services Connect Environmental Change to Human Health Outcomes

    SciTech Connect

    Bayles, Brett R.; Brauman, Kate A.; Adkins, Joshua N.; Allan, Brian F.; Ellis, Alicia M.; Goldberg, Tony L.; Golden, Christopher D.; Grigsby-Toussaint, Diana S.; Myers, Samuel S.; Osofsky, Steven A.; Ricketts, Taylor H.; Ristaino, Jean B.

    2016-06-29

    Global environmental change, driven in large part by human activities, profoundly impacts the structure and functioning of Earth’s ecosystems (Millennium Ecosystem Assessment 2005). We are beginning to push beyond planetary boundaries (Steffan et al. 2015), and the consequences for human health remain largely unknown (Myers et al. 2013). Growing evidence suggests that ecological transformations can dramatically affect human health in ways that are both obvious and obscure (Myers and Patz 2009; Myers et al. 2013). The framework of ecosystem services, designed to evaluate the benefits that people derive from ecosystem products and processes, provides a compelling framework for integrating the many factors that influence the human health response to global change, as well as for integrating health impacts into broader analyses of the impacts of this change

  11. Study of Environmental Arctic Change (SEARCH): Scientific Understanding of Arctic Environmental Change to Help Society Understand and Respond to a Rapidly Changing Arctic.

    NASA Astrophysics Data System (ADS)

    Wiggins, H. V.; Myers, B.

    2015-12-01

    The Study of Environmental Arctic Change (SEARCH) is a U.S. program with a mission to provide a foundation of Arctic change science through collaboration with the research community, funding agencies, and other stakeholders. To achieve this mission, SEARCH: Generates and synthesizes research findings and promotes Arctic science and scientific discovery across disciplines and among agencies. Identifies emerging issues in Arctic environmental change. Provides scientific information to Arctic stakeholders, policy-makers, and the public to help them understand and respond to arctic environmental change. Facilitates research activities across local-to-global scales, with an emphasis on addressing needs of decision-makers. Collaborates with national and international science programs integral to SEARCH goals. This poster presentation will present SEARCH activities and plans, highlighting those focused on providing information for decision-makers. http://www.arcus.org/search

  12. (Meeting on human dimensions of global environmental change)

    SciTech Connect

    Rayner, S.

    1990-12-18

    Traveler attended the meeting of the Standing Committee on the Human Dimensions of Global Environmental Change of the International Social Science Council (ISSC) and the Scientific Symposium organized by the Standing Committee. The purpose of the meeting and symposium was to discuss the Draft Framework and the Workplan of the Standing Committee prior to its presentation to the 1990 Congress of the ISSC on November 28--30, 1990. The meetings indicate that ORNL Global Environmental Studies Center is on the international leading edge of human dimensions research, except in the area of human dimensions data systems. This weakness could be rectified by close collaboration with the efforts of the Consortium for International Earth Science Information Network (CIESIN) in Michigan.

  13. Climate change mitigation and adaptation in strategic environmental assessment

    SciTech Connect

    Wende, Wolfgang; Bond, Alan; Bobylev, Nikolai; Stratmann, Lars

    2012-01-15

    Countries are implementing CO{sub 2} emission reduction targets in order to meet a globally agreed global warming limit of +2 Degree-Sign C. However, it was hypothesised that these national reduction targets are not translated to regional or state level planning, and are not considered through Strategic Environmental Assessment (SEA) in order to meet emission reduction obligations falling on the transport, energy, housing, agriculture, and forestry sectors. SEAs of land use plans in the German state of Saxony, and the English region of the East of England were examined for their consideration of climate change impacts based on a set of criteria drawn from the literature. It was found that SEAs in both cases failed to consider climate change impacts at scales larger than the boundary of the spatial plan, and that CO{sub 2} reduction targets were not considered. This suggests a need for more clarity in the legal obligations for climate change consideration within the text of the SEA Directive, a requirement for monitoring of carbon emissions, a need for methodological guidance to devolve global climate change targets down to regional and local levels, and a need for guidance on properly implementing climate change protection in SEA. - Highlights: Black-Right-Pointing-Pointer Strategic Environmental Assessments (SEA) of 12 land use plans from Germany and England have been examined. Black-Right-Pointing-Pointer SEA failed to consider climate change impacts at scales larger than the boundary of the land use plans. Black-Right-Pointing-Pointer SEA should be an important instrument for climate protection. Black-Right-Pointing-Pointer Concrete steps for climate protection mainstreaming into SEA at the European Union and national levels have been suggested.

  14. Environmental NGOs in Ecuador: an economic analysis of institutional change.

    PubMed

    Meyer, C A

    1993-01-01

    Nongovernmental organizations (NGOs) in Latin America have grown more rapidly than has our understanding of the economic and political implications of this major institutional change. In Ecuador, between 1984 and late 1992, at least 24 new environmental NGOs emerged. An economist does a case study of them, especially Fundacion Natura (FN) in Ecuador, to understand their role and behavior which are a large part of environmental politics in Latin America. NGOs are successful because the public sector cannot meet the countries' needs and donors want to help NGOs, thereby providing the demand. For example, FN has received funding from USAID, World Wildlife Fund, the International Union for the Conservation of Nature, and other groups. FN charges donors 15% to cover administrative costs while many other NGOs do not receive international funding for administrative costs. FN is well connected with the public sector which is supportive and beneficial. FN activities complement the public sector's efforts in the environment. Further, it is well connected with private industry from whom it receives financial support. It has been criticized for supporting industry on some environmental issues, however. In fact, its Cuenca chapter split from FN in 1984 to form Tierra Viva, because FN sided with industry when industry wanted to build on agricultural land in Cuenca. FN's relationship with USAID is strained. FN is successful because it employs quality personnel who are committed to FN objectives. Yet FN and other NGOs do not have the monetary incentives for efficient production. Most other NGOs are financially strapped and depend on volunteers. The more radical environmental NGOs do not accept donations from the private sector and do not want to work with government. Despite the influence donors have on NGOs, the NGOs' powerful presence and their environmental education programs have consequences beyond donor control (e.g., FN and USAID).

  15. Rapid body size decline in Alaskan Pleistocene horses before extinction.

    PubMed

    Guthrie, R Dale

    2003-11-13

    About 70% of North American large mammal species were lost at the end of the Pleistocene epoch. The causes of this extinction--the role of humans versus that of climate--have been the focus of much controversy. Horses have figured centrally in that debate, because equid species dominated North American late Pleistocene faunas in terms of abundance, geographical distribution, and species variety, yet none survived into the Holocene epoch. The timing of these equid regional extinctions and accompanying evolutionary changes are poorly known. In an attempt to document better the decline and demise of two Alaskan Pleistocene equids, I selected a large number of fossils from the latest Pleistocene for radiocarbon dating. Here I show that horses underwent a rapid decline in body size before extinction, and I propose that the size decline and subsequent regional extinction at 12,500 radiocarbon years before present are best attributed to a coincident climatic/vegetational shift. The present data do not support human overkill and several other proposed extinction causes, and also show that large mammal species responded somewhat individualistically to climate changes at the end of the Pleistocene.

  16. Forest environmental investments and implications for climate change mitigation.

    PubMed

    Alig, Ralph J; Bair, Lucas S

    2006-01-01

    Forest environmental conditions are affected by climate change, but investments in forest environmental quality can be used as part of the climate change mitigation strategy. A key question involving the potential use of forests to store more carbon as part of climate change mitigation is the impact of forest investments on the timing and quantity of forest volumes that affect carbon storage. Using an economic optimization model, we project levels of U.S. forest volumes as indicators of carbon storage for a wide range of private forest investment scenarios. Results show that economic opportunities exist to further intensify timber management on some hectares and reduce the average timber rotation length such that the national volume of standing timber stocks could be reduced relative to projections reflecting historical trends. The national amount of timber volume is projected to increase over the next 50 yr, but then is projected to decline if private owners follow an economic optimization path, such as with more forest type conversions and shorter timber rotations. With perfect foresight, future forest investments can affect current timber harvest levels, with intertemporal linkages based on adjustments through markets. Forest investments that boost regenerated timber yields per hectare would act to enhance ecosystem services (e.g., forest carbon storage) if they are related to the rate of growth and extent of growing stock inventory.

  17. Coastal Aquifer Response to Environmental Change - Implications for Future Projections

    NASA Astrophysics Data System (ADS)

    Post, V.

    2014-12-01

    Coastal aquifers are important resources for water supply, and are increasingly stressed by population increase and the growing water demand for irrigation and other uses. Concern exists that these current pressures will be compunded by the adverse impacts of future environmental change, in particular sea-level rise. Numerous studies have investigated the effect of the expected sea-level rise durring the 21st century on the salintiy distribution in coastal groundwater systems. In many of these studies, the predicted changes due to an increase in sea level are typically seen as a departure from a steady-state situation. But many other studies have provided abundant evidence that groundwater systems in coastal areas are not in equilibrium with the present-day boundary conditions, i.e., coastline configuration and climate. This is borne out by, for example, the salinity distribution of groundwater, which does not obey the classical configuration of an intruded wedge of seawater extending inland from the coastline. This paper will argue that coastal aquifers systems are in a continuous state of transition. The relevance of future environmental change within the context of long-term trends will be discussed and exemplified by case studies of coastal aquifers in different parts of the world. It will be argued that the conceptualization of coastal groundwater systems, and in particular the connection between their onshore and offshore parts, is a major source of uncertainty in studies that aim to quantify the impact of sea-level rise on coastal groundwater resources.

  18. Human influence on distribution and extinctions of the late Pleistocene Eurasian megafauna.

    PubMed

    Pushkina, Diana; Raia, Pasquale

    2008-06-01

    Late Pleistocene extinctions are of interest to paleontological and anthropological research. In North America and Australia, human occupation occurred during a short period of time and overexploitation may have led to the extinction of mammalian megafauna. In northern Eurasia megafaunal extinctions are believed to have occurred over a relatively longer period of time, perhaps as a result of changing environmental conditions, but the picture is much less clear. To consider megafaunal extinction in Eurasia, we compare differences in the geographical distribution and commonness of extinct and extant species between paleontological and archaeological localities from the late middle Pleistocene to Holocene. Purely paleontological localities, as well as most extinct species, were distributed north of archaeological sites and of the extant species, suggesting that apart from possible differences in adaptations between humans and other species, humans could also have a detrimental effect on large mammal distribution. However, evidence for human overexploitation applies only to the extinct steppe bison Bison priscus. Other human-preferred species survive into the Holocene, including Rangifer tarandus, Equus ferus, Capreolus capreolus, Cervus elaphus, Equus hemionus, Saiga tatarica, and Sus scrofa. Mammuthus primigenius and Megaloceros giganteus were rare in archaeological sites. Carnivores appear little influenced by human presence, although they become rarer in Holocene archaeological sites. Overall, the data are consistent with the conclusion that humans acted as efficient hunters selecting for the most abundant species. Our study supports the idea that the late Pleistocene extinctions were environmentally driven by climatic changes that triggered habitat fragmentation, species range reduction, and population decrease, after which human interference either by direct hunting or via indirect activities probably became critical.

  19. Onset of major Pleistocene glaciations in the Alps

    NASA Astrophysics Data System (ADS)

    Muttoni, G.; Carcano, C.; Garzanti, E.; Ghielmi, M.; Piccin, A.; Pini, R.; Rogledi, S.; Sciunnach, D.

    2003-04-01

    Since alligators patrolled Greenland swamps in the Eocene, the Earth's climate underwent significant cooling, which culminated in the Pleistocene Ice Age with recurring glaciations in vast regions of the Alps, Eurasia and North America, and overgrowth of polar icecaps in Antarctica and Greenland. During main Pleistocene glacial penetrations, the Alpine icecap invaded the low gradients of the Central Europe uplands and Italian Po plain. Peri-glacial sedimentary basins such as the Po Basin are natural collectors of past biological and climatic changes involving the waxing and waning of major icecaps. We have found in a 200m-thick core from the central Po plain near Milan stratigraphic evidence for a major glacial pulsation of the nearby Alpine icecap, which occurred in correspondence of a seismically traceable unconformity of regional relevance, termed the "Red Unconformity" (RU) in Eni/Agip terminology. The RU is associated with a major reorganization of vegetation cover and Alpine drainage pattern. The age of the RU was constrained magnetostratigraphically to the the first major Pleistocene glacio-eustatic low-stand at 0.87Ma (Oxygen Isotope Stage 22). This corresponds to the end of the "Mid Pleistocene Revolution" (MPR), a marked reorganization of northern hemisphere glaciation pattern which took place in the late Early Pleistocene. We suggest that the MPR/MIS 22 was associated with the onset of the first major Pleistocene glaciation in the Alps. Noticing the similarity in number of major Pleistocene glacieustatic low-stands starting with MIS 22, and the four-fold Alpine glacial subdivision of Penck and Brückner (1909), we conclude that "Penck and Brückner in 1909 may not have been, after all, that wrong" (Kukla and Cilek, 1996).

  20. Environmental changes and vulnerability in the Gharbi Island (Kerkennah, Tunisia)

    NASA Astrophysics Data System (ADS)

    Etienne, L.; Bouaziz, R.; Dahech, S.; Daoud, A.; Beltrando, G.

    2012-04-01

    Most reliable models of climatic observation and forecast show that the south of the Mediterranean perimeter is threatened by important variations of environmental conditions. The Gharbi Island that belongs to the Kerkennah archipelago is located 20 km away from the Sfax coast and is likely to undergo the consequences of these regional-scale evolutions. In addition, the socio-economic changes that started in the 80's may have an impact on land use. Indeed, marine conditions changed and overfishing causes the decrease of fish quantity and the leaving of the fisher in favor of agriculture. To enlighten changes of various natures and understand the mechanisms of their origin or development, we performed a comparison of land use on 4 dates over the last 50 years, using photointerpretation on two high resolution images (1963: aerial photography and 2010: Spot image; 2,5m resolution) and remote sensing on two Landsat 5 TM images (1984 and 2011). To support and complete our large scale observations, we also added photographic data gathered during two field campaigns. The first change we observed is a urban extension (stakes) predominantly imputed to the construction of holiday resort for Tunisian citizen, and for a minority to international tourism. We also found that the number of agricultural parcels (stakes) has been multiplied during the past decades in response of changes on agricultural practices, and that an irrigated zone has been created in response to the increase of hydric stress and of farmers. Finally, we describe an enlargement of sebkhas (low, salty and liable to flooding areas (hazard)) that might likely be caused by climatic and environmental evolution like sea level rise and subsidence. We conclude one the one hand that vulnerability and also risks of salinization and loss of farmland around the sebkhas and in the irrigated zone have increase and on the other hand that human infrastructures that are very close or in the sebkhas are vulnerable to sea

  1. Planetary Habitability and Rapid Environmental Change: The Biological Perspective

    NASA Astrophysics Data System (ADS)

    Schulze-Makuch, D.; Fairen, A.; Irwin, L.

    2012-12-01

    Environmental conditions can change drastically and rapidly during the natural history of a planetary body. We have detailed evidence of these dramatic events from Venus, Earth, Mars, and Titan. Most of these occurrences seem to be triggered by astronomical events such as asteroid impacts or supernova explosions; others are triggered by the planet or moon itself (e.g., supervolcano eruptions). The associated question is always how these events affect the habitability of a planet, particularly the origin and presence of life. Under what conditions would such a drastic event be so catastrophic that it would prohibit the origin of life or be so devastating to existing organisms, that life would not be able to recover and be all but extinguished from a planet? Under what conditions would such an event be positive for the evolution of life, for example spurring life via mass extinctions and associated vacant habitats to the invention of new body plans and higher complexity? Here, we provide insights of what we can learn from the natural history of our own planet, which experienced many environmental disasters and abrupt climate changes, from the impact event that created the Moon to the extinction of the dinosaurs. We apply these insights to other planetary bodies and the question about the presence of life. One example is Mars, which underwent drastic environmental changes at the end of the Noachian period. Assuming that microbial life became established on Mars, could it have survived, perhaps by retreating to environmental niches? Life just starting out would have certainly been more vulnerable to extinction. But how far would it have to have evolved to be more resistant to potential extinction events? Would it have to be global in distribution to survive? Another example is Venus. Should Venus be seen as an example where life, which possibly arose in the first few hundred million years when the planet was still in the habitable zone, would have had no chance to

  2. Evolution of the siliciclastic-carbonate shelf system of the northern Kenyan coastal belt in response to Late Pleistocene-Holocene relative sea level changes

    NASA Astrophysics Data System (ADS)

    Accordi, Giovanni; Carbone, Federico

    2016-11-01

    A classification of depositional environments of the Lamu Archipelago is proposed based on a sedimentary facies analysis of unconsolidated and hard bottoms of the study area. The genesis of the siliciclastic-carbonate depositional pattern, typical of this East African region, is closely related both to the presence of a quartz-dominate Pleistocene riverine net-flooded during the Holocene sea level rise-and to the coeval development on the shallow shelf of a coral ecosystem producing vast skeletal sediments. The present facies pattern originates from the variable contribution in time and space of three sediment types: skeletal carbonate, quartz and palimpsest debris. The facies analysis allowed to distinguish 10 depositional facies and to differentiate them into three main types of substratum: soft bottom, reefal hard bottom and non-reefal hard bottom. These three types define both the loose facies typical of the channelized coastal belt and several facies of the shallow shelf. In the first, the amounts and textures of the stored sediment are strictly related to three major geomorphic types of substratum: sheltered mangal flat, shallow channel and deep channel. In the second and the third, a wide range of textures is related to coastal flats, benches, islets and emerging rocks. This modern facies pattern is implemented through a series of evolutionary phases: i-during the Last Interglacial Period, since isotope substage 5b, the shallow shelf-above -20 m-is permanently exposed for about 80 ka, with erosion, karstification and cuts of river channels through the shelf; ii-after the Last Glacial Maximum, when the sea level fell to about 110-115 m b.p.s.l. (below present sea level) at 18-17 ka BP, the sea level rose at -20 m for about 9 ka, flooding the shallow shelf area and gradually drowning the riverine net; iii-the maximum flooding of the coastal belt was reached at about 4.5 ka BP, when a gradual moisture reduction caused a decrease of siliciclastic sediment supply

  3. Records of urbanism, imperialism, & environmental change in southeastern Turkey

    NASA Astrophysics Data System (ADS)

    Nicoll, K.

    2012-04-01

    Assessing the "human footprint" on the landscape since prehistory requires some comparison of the degree and pace of such changes, and the cause-and-effect, as well as the ability to resolve the anthropogenic signal from from patterns of "natural" environmental variation. The deep archaeological record provides valuable insights regarding the timeframe prior to the European industrial revolution; studies at specific localities may help resolve differences between anthropogenically-mediated changes and "natural" climatic changes. Results of various archaeological and palaeoecological archives across the Fertile Crescent indicates that rapid changes on landforms and biota have occurred since the beginnings of agriculture and urbanization. Work at key localities suggests that periods of imperialism such as the Neo-Assyrian ~9th century BCE are synchronous with sediment disturbances and deforestation in southeastern Turkey. New findings from geomorphic and archaeological survey and investigation in the Tigris watershed near Diyarbakir are correlated with various records across the broader region (e.g., Lake Van, Konya lakes, etc) in order to assess the spatial and temporal changes brought about by human population growth and increased exploitation of natural resources during phases of empire-building.

  4. Pleistocene Megafaunal Collapse in North America Preceded the Younger Dryas: Evidence from the Midwest

    NASA Astrophysics Data System (ADS)

    Gill, J. L.; Donnelly, J.; Jackson, S. T.; Lininger, K. B.; Marsicek, J. P.; Robinson, G.; Simonson, B. M.; Williams, J. W.

    2009-12-01

    The recent Younger Dryas (YD) impact theory suggests that an extraterrestrial impact event at 12,900 calendar years BP was responsible for rapid and widespread environmental change, including the extinction of the Pleistocene megafauna. Evidence for such an event is expected to be preserved in lake sediments; lakes are robust archives of environmental change, including abrupt events such as the YD. Sporormiella, a dung fungal proxy for megafaunal presence, has recently been added to classic lake sediment proxies such as pollen and charcoal. Sporormiella spores have been found to be abundant in Pleistocene deposits and mostly absent during the Holocene until the historic introduction of domestic grazers, and are therefore a suitable proxy for Pleistocene herbivory regimes. At Appleman Lake, IN, fossil pollen, charcoal, and Sporormiella were analyzed to reconstruct changes in vegetation, fire regime, and megafaunal presence. The Sporormiella record indicates that Pleistocene megaherbivores declined from 14.6 to 13.7 ka calendar BP, well before the onset of Younger Dryas cooling and the proposed impact event. However, these data are consistent with the oldest well-dated evidence of pre-Clovis human presence from butchered mammoth remains in the Midwest. Immediately following the Sporormiella decline, pollen and charcoal data indicate shifts in plant community composition and an increase in fire frequency, possibly due to the release of palatable hardwood taxa and a build-up of landscape biomass following the local extirpation of herbivores. While the onset of the decline does correspond with Bølling-Allerød warming, the mechanism for the decline does not appear to be vegetation-induced habitat loss. Additionally, sediment cores from Appleman and Spicer Lakes, IN, and Silver Lake in Ohio have been analyzed for evidence of an extra-terrestrial impact, including mineral spherules, charcoal peaks, ET-associated elements, magnetic grains, and loss-on-ignition. Our sites

  5. Environmental health risk assessment and management for global climate change

    NASA Astrophysics Data System (ADS)

    Carter, P.

    2014-12-01

    This environmental health risk assessment and management approach for atmospheric greenhouse gas (GHG) pollution is based almost entirely on IPCC AR5 (2014) content, but the IPCC does not make recommendations. Large climate model uncertainties may be large environmental health risks. In accordance with environmental health risk management, we use the standard (IPCC-endorsed) formula of risk as the product of magnitude times probability, with an extremely high standard of precaution. Atmospheric GHG pollution, causing global warming, climate change and ocean acidification, is increasing as fast as ever. Time is of the essence to inform and make recommendations to governments and the public. While the 2ºC target is the only formally agreed-upon policy limit, for the most vulnerable nations, a 1.5ºC limit is being considered by the UNFCCC Secretariat. The Climate Action Network International (2014), representing civil society, recommends that the 1.5ºC limit be kept open and that emissions decline from 2015. James Hansen et al (2013) have argued that 1ºC is the danger limit. Taking into account committed global warming, its millennial duration, multiple large sources of amplifying climate feedbacks and multiple adverse impacts of global warming and climate change on crops, and population health impacts, all the IPCC AR5 scenarios carry extreme environmental health risks to large human populations and to the future of humanity as a whole. Our risk consideration finds that 2ºC carries high risks of many catastrophic impacts, that 1.5ºC carries high risks of many disastrous impacts, and that 1ºC is the danger limit. IPCC AR4 (2007) showed that emissions must be reversed by 2015 for a 2ºC warming limit. For the IPCC AR5 only the best-case scenario RCP2.6, is projected to stay under 2ºC by 2100 but the upper range is just above 2ºC. It calls for emissions to decline by 2020. We recommend that for catastrophic environmental health risk aversion, emissions decline

  6. Long-term Environmental Observatories as Predictors of Regional Environmental Change: An Oregon Example

    NASA Astrophysics Data System (ADS)

    Ashkenas, L.; Gregory, S.; van Sickle, J.

    2005-05-01

    Predictions of future environmental change often rest on long-term datasets collected in reference areas. However, many current landscape conversions occur on very different portions of the landscape than these sites. Can information from localized reference sites be used to predict regional environmental changes? We compared results from three nested watersheds: a small reference basin, the H.J. Andrews Experimental Forest (a Long-Term Ecological Research site, 64 km2), the McKenzie (3465 km2) and the Willamette (29727 km2) for past (1850, pre-Euroamerican settlement), present, and three alternate futures in 2050. Based on empirical field studies, we modeled changes to aquatic and riparian indicators, such as numbers and potential habitat of cutthroat trout, and riparian cover type. The relatively small, homogenous reference observatory was a poor predictor of more complex landscapes. For example, between 1850 and 1990, cutthroat trout habitat declined 50% in the Willamette, 19% in the McKenzie, but only 10% in the H.J. Andrews. Regional networks of observatories ideally should consist of (1) relatively pristine reference areas used to elucidate fundamental local ecological processes, (2) extensively altered sites, and (3) locations on the periphery of rapidly changing portions of the landscape where future intensive impacts, such as landscape conversion, are probable.

  7. A Novel Tropical Dry Forests: A Response to Environmental Change.

    NASA Astrophysics Data System (ADS)

    Lugo, A. E.; Molina, S.

    2015-12-01

    Dry Forest environments are favorable to human settlement and activities, leading to deforestation, agricultural enterprises, land degradation, and abandonment. As a result, tropical dry forests are vulnerable and experience a high rate of cover loss, which often requires restoration activities. We have studied the natural regeneration of dry forests in Puerto Rico following a variety of human activities including farming, cattle pasturing, charcoal production, and human dwellings. Our results show a high level of forest resilience to anthropogenic disturbances but also a change of species composition relative to undisturbed native forests. This novelty of forest composition represents a natural response to environmental changes induced by human activity and pre-adapts forests to conditions in the Anthropocene.

  8. Global atmospheric change and research needs in environmental health sciences

    SciTech Connect

    Goldstein, B.D. ); Reed, D.J. )

    1991-12-01

    On November 6-7, 1989, the National Institute of Environmental Health Sciences (NIEHS) held a conference on Global Atmospheric Change and Human Health. As a result, and in the months since this conference, many important areas of research have been identified with regard to the impacts of climatic changes on human health. To develop comprehensive research programs that address important human health issues related to global warming, it is necessary to begin by recognizing that some of the health effects will be direct such as those due to temperature changes, and others will be indirect consequences of environmental alterations resulting in crop loss, changing disease vectors, population migration, etc. It should also be recognized that the conditions leading to global warming have importance to human health and the environment other than through increasing concentrations of CO[sub 2] in the atmosphere, rising surface temperatures, and rising sea levels. Much of the increase in CO[sub 2] in the atmosphere is due to the increased combustion of fossil fuels for transportation and electric power production. Over the next 30 years, the demand for electrical power is expected to grow at a rate of 2 to 4% per year in the United States alone, and even faster growth is likely for developing countries. Much of this energy will be derived from the combustion of fossil fuels, including coal, which result in pollutant emissions to the air such as metals, radioactivity, SO[sub x], NO[sub x], and particles. Therefore, with increasing concentrations of CO[sub 2] there will not only be the effects of global warming on health, but also increasing concentrations of many serious air pollutants in urban areas, including the precursors of acid rain and acid deposition over large regional areas.

  9. South Polar Residual Cap Geomorphology and Inferred Environmental Changes

    NASA Astrophysics Data System (ADS)

    Byrne, S.; Ingersoll, A.; Pathare, A.

    2003-12-01

    The CO2 southern residual cap (SRC) both controls circulation patterns regionally and buffers the atmospheric pressure globally. In turn this CO2 deposit is affected by changes in environmental conditions wrought by external forces such as dust storm activity. Mars Global Surveyor data of this area have revealed a rich variety of geomorphic features (1) of which there are several distinct classes. These different classes may be end members of the same basic process of insolation driven ablation. We are currently investigating two types of SRC features. Swiss-cheese features (SCF) are depressions characterized by flat floors and steep walls, which retreat 1-3 meters each Martian year (2). In some regions they have a definite symmetry axis along the north-south direction (3). After the seasonal frost disappears the residual ice exposed in the walls has a lower albedo (4). Previously (5) we modeled the evolution and growth of these depressions as a hole in a layer of CO2 ice underlain by water ice, which best explains their morphologic and thermal properties. The observed thickness of the CO2 slab can be as high as 8 meters but in general is much lower. Larger SCF?s commonly possess a raised central island of CO2 surrounded by a moat that penetrates to the underlying water ice (3). The fast rate of wall retreat observed (2) combined with the small sizes of the SCF?s indicate that all SCF?s visible today were created geologically recently. Within a particular region the size distribution is quite narrow (3): no larger (older) or smaller (younger) features were seen indicating that some relatively abrupt change in environmental conditions initiated the growth of this particular population of features. Fingerprint terrain (1) are areas with evenly spaced parallel ridges, which are steeper on one side. These ridges may have small areas of water ice exposed in the intervening troughs. Their wavelength is on the order of 70-90m with the steep edges facing northeast although

  10. Coping with global environmental change -- role of science and democracy.

    PubMed

    Menon, M G

    The world's population increased form about 3 billion in 1960 to 4 billion in 1974, to 5 billion in 1987, and it is projected to grow to 6 billion by 1991 and to 8 billion by 1992. Finite, nonrenewable resources have to satisfy the increased need for sustenance of this population excess in a sustainable economic development mold. Human activity has upset natural processes with negative environmental effects: Minamata disease in Japan caused by heavy metal pollution, global deforestation, and acid rain. The 1972 Conference on Human Environment in Stockholm dealt with industrial pollution. The UN Environment Programme (UNEP) was established subsequently. The theory of global warming caused by emissions of carbon dioxide, methane, nitrogen oxides, and halogens as predicted by a Swedish scientist decades ago is accumulating a body of evidence. The International Geosphere Biosphere Programme (IGBP) of the International Council of Scientific Unions attempt to explore the Earth's physical, chemical, and biological processes to predict global environmental changes. Success mandates data availability. Paleoclimatic evidence indicates previous cataclysms caused by climate change, thus agriculture could be affected massively by global warming. Improved scientific analysis of greenhouse gas emissions and crop simulation models for major agricultural areas are needed. The North-South dialogue in UN forums has been acrimonious without much success, although international cooperation has been fruitful with the adoption of the Montreal Protocol on phasing out ozone-depleting chlorofluorocarbons. Such cooperation is needed on energy consumption and sources.

  11. Interactions between environmental changes and brain plasticity in birds.

    PubMed

    Barnea, Anat

    2009-09-01

    Neurogenesis and neuronal recruitment occur in many vertebrates, including humans. Most of the new neurons die before reaching their destination. Those which survive migrate to various brain regions, replace older ones and connect to existing circuits. Evidence suggests that this replacement is related to acquisition of new information. Therefore, neuronal replacement can be seen as a form of brain plasticity that enables organisms to adjust to environmental changes. However, direct evidence of a causal link between replacement and learning remains elusive. Our hypothesis is that increased neuronal recruitment is associated with increase in memory load. Moreover, since neuronal recruitment is part of a turnover process, we assume that the same conditions that favor survival of some neurons induce the death of others. I present studies that investigated the effect of various behaviors and environmental conditions (food-hoarding, social change, reproductive cycle) on neuronal recruitment and survival in adult avian brains, and discuss how these phenomena relate to the life of animals. I offer a frame and rationale for comparing neuronal replacement in the adult brain, in order to uncover the pressures, rules, and mechanisms that govern its constant rejuvenation. The review emphasizes the importance of using various approaches (behavioral, anatomical, cellular and hormonal) in neuroethological research, and the need to study natural populations, in order to fully understand how neurogenesis and neuronal replacement contribute to life of animals. Finally, the review indicates to future directions and ends with the hope that a better understanding of adult neuronal replacement will lead to medical applications.

  12. Acculturation and environmental change impacts dietary habits among adult Hmong.

    PubMed

    Franzen, Lisa; Smith, Chery

    2009-02-01

    Focus groups (n=65) were conducted with Hmong adults in St. Paul/Minneapolis, MN to determine how environmental factors, acculturation, and food insecurity influence dietary behavior, body mass index (BMI), and health. Acculturation was assessed by examining linguistic, social, and eating behavior, length of time in the US, and BMI for B-TL(1) (born in Thailand/Laos and in US < or =5 years), B-TL(2) (in Thailand/Laos through adolescence, had food memories, and in US >5 years), and B-US (born in US or in Thailand/Laos less than 8 years and no food memories from there). Acculturation was associated with years lived in the US, household size and income, and food assistance usage. Years lived in the US was correlated with food assistance usage, education, household size and income, and perception of diet. B-TL(1) and B-TL(2) were on average overweight (BMI> or =25<30), US men were obese (mean BMI=32.4+/-7.4), and women were overweight (mean BMI=29.1+/-6.8). Themes identified were cultural values impact eating and lifestyle behaviors, food insecurity history influences post-migration behavior, acculturation impacts BMI through diet and exercise, and health status is influenced by changed environments. Environmental changes and increased acculturation have negatively impacted the weight and health of Hmong adults.

  13. Carbon trading, climate change, environmental sustainability and saving planet Earth

    NASA Astrophysics Data System (ADS)

    Yim, W. W.

    2009-12-01

    Carbon trading namely the reduction of future carbon dioxide levels has been widely touted as a solution needed to counter the problem of climate change. However, there are enormous risks involved as the measure tackles only one of the causes of climate change and may prove to be ineffective. This presentation highlights ten points relevant to the discussion on carbon trading, climate change, environmental sustainability and saving planet Earth for increasing public awareness. They include: (1) Climate has changed throughout Earth’s history. (2) The present level of about 388 parts per million level of carbon dioxide in the atmosphere has already exceeded the maximum level of the past 800,000 years. This value is obtained from air bubbles trapped within the ice in Antarctica but the consequence of further increases remains uncertain. (3) Earth scientists do not have an overwhelming consensus on whether carbon trading alone is an effective measure in mitigating climate change. (4) The present state of the Earth’s demise is largely the result of human actions including population growth and the mismanagement of the Earth. (5) The latest evidence on sea-level changes in the South China Sea a far-field region unaffected by glacial isostatic readjustment is not in support of a ‘rapid’ rate of future sea-level rise through global warming. (6) Volcanic eruptions have an important role in driving the Earth’s climate. Examples of temperature lowering as well as abnormally wet and dry years can both be found in the instrumental record. (7) Humans have drastically modified the ‘natural’ water cycle. This is however not a well recognized cause of climate change compared to the emission of greenhouse gases through fossil fuel consumption. (8) The bulk (~75%) of the rise in mean annual temperature of about 1oC observed at the Hong Kong Observatory Station since record began in 1884 is best explained by the thermal heat island effect. (9) No evidence has been found

  14. Retardation of arsenic transport through a Pleistocene aquifer

    PubMed Central

    van Geen, Alexander; Bostick, Benjamín C.; Trang, Pham Thi Kim; Lan, Vi Mai; Mai, Nguyen-Ngoc; Manh, Phu Dao; Viet, Pham Hung; Radloff, Kathleen; Aziz, Zahid; Mey, Jacob L.; Stahl, Mason O.; Harvey, Charles F.; Oates, Peter; Weinman, Beth; Stengel, Caroline; Frei, Felix; Kipfer, Rolf; Berg, Michael

    2013-01-01

    Groundwater drawn daily from shallow alluvial sands by millions of wells over large areas of South and Southeast Asia exposes an estimated population of over 100 million to toxic levels of arsenic (1). Holocene aquifers are the source of widespread arsenic poisoning across the region (2, 3). In contrast, Pleistocene sands deposited in this region more than ~12,000 years ago mostly do not host groundwater with high levels of arsenic. Pleistocene aquifers are increasingly used as a safe source of drinking water (4) and it is therefore important to understand under what conditions low levels of arsenic can be maintained. Here we reconstruct the initial phase of contamination of a Pleistocene aquifer near Hanoi, Vietnam. We demonstrate that changes in groundwater flow conditions and the redox state of the aquifer sands induced by groundwater pumping caused the lateral intrusion of arsenic contamination over 120 m from Holocene aquifer into a previously uncontaminated Pleistocene aquifer. We also find that arsenic adsorbs onto the aquifer sands and that there is a 16–20 fold retardation in the extent of the contamination relative to the reconstructed lateral movement of groundwater over the same period. Our findings suggest that arsenic contamination of Pleistocene aquifers in South and Southeast Asia as a consequence of increasing levels of groundwater pumping have been delayed by the retardation of arsenic transport. PMID:24025840

  15. Observations of environmental change in Grand Canyon, Arizona

    USGS Publications Warehouse

    Webb, Robert H.; Melis, Theodore S.; Valdez, Richard A.

    2002-01-01

    Few scientific data have been collected on pre-dam conditions of the Colorado River corridor through Grand Canyon National Park. Using historical diaries, interviews with pre-dam river runners (referred to as the ?Old Timers?), and historical scientific data and observations, we compiled anecdotal information on environmental change in Grand Canyon. The most significant changes are the: lowering of water temperature in the river, near-elimination of heavily sediment-laden flows, erosion of sand bars, invasion of non-native tamarisk trees, reduction in driftwood, development of marshes, increase in non-native fish at the expense of native fishes, and increase in water bird populations. In addition, few debris flows were observed before closure of Glen Canyon Dam, which might suggests that the frequency of debris flows in Grand Canyon has increased. Other possible changes include decreases in bat populations and increases in swallow and bighorn sheep populations, although the evidence is anecdotal and inconclusive. These results provide a perspective on managing the Colorado River that may allow differentiation of the effects of Glen Canyon Dam from other processes of change.

  16. Strategies for sustainable management of renewable resources during environmental change.

    PubMed

    Lindkvist, Emilie; Ekeberg, Örjan; Norberg, Jon

    2017-03-15

    As a consequence of global environmental change, management strategies that can deal with unexpected change in resource dynamics are becoming increasingly important. In this paper we undertake a novel approach to studying resource growth problems using a computational form of adaptive management to find optimal strategies for prevalent natural resource management dilemmas. We scrutinize adaptive management, or learning-by-doing, to better understand how to simultaneously manage and learn about a system when its dynamics are unknown. We study important trade-offs in decision-making with respect to choosing optimal actions (harvest efforts) for sustainable management during change. This is operationalized through an artificially intelligent model where we analyze how different trends and fluctuations in growth rates of a renewable resource affect the performance of different management strategies. Our results show that the optimal strategy for managing resources with declining growth is capable of managing resources with fluctuating or increasing growth at a negligible cost, creating in a management strategy that is both efficient and robust towards future unknown changes. To obtain this strategy, adaptive management should strive for: high learning rates to new knowledge, high valuation of future outcomes and modest exploration around what is perceived as the optimal action.

  17. Changes in environmental impacts of major crops in the US

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Suh, Sangwon

    2015-09-01

    As with life cycle assessment (LCA) studies in general, agricultural LCAs often rely on static and outdated inventory data, but literature suggests that agricultural systems may be highly dynamic. Here, we applied life cycle impact assessment methods to investigate the trends and underlying drivers of changes in non-global environmental impacts of major crops in the US. The results show that the impact per hectare corn and cotton generated on the ecological health of freshwater systems decreased by about 50% in the last decade. This change is mainly due to the use of genetically modified (GM) crops, which has reduced the application of insecticides and relatively toxic herbicides such as atrazine. However, the freshwater ecotoxicity impact per hectare soybean production increased by 3-fold, mainly because the spread of an invasive species, soybean aphid, has resulted in an increasing use of insecticides. In comparison, other impact categories remained relatively stable. By evaluating the relative ecotoxicity potential of a large number of pesticides, our analysis offers new insight into the benefits associated with GM crops. Our study also implies that because different impact categories show different degrees of changes, it is worthwhile focusing on the rapidly changing categories when updating agricultural LCA databases under time and resource constraints.

  18. Late Miocene biomarker and pollen records in Southeast Atlantic Ocean sediments indicate environmental changes

    NASA Astrophysics Data System (ADS)

    Rommerskirchen, Florian; Dupont, Lydie; Condon, Tegan; Mollenhauer, Gesine; Schefuß, Enno

    2010-05-01

    The Late Miocene epoch is characterized by fundamental changes in Earth‘s climate system: sea-level variability, changes in surface- and deep-water circulation, increase in upwelling intensity along the coasts and turnover in marine and terrestrial biota [1,2]. It is thought that plants using the CO2 concentrating C4 mechanism for photosynthesis potentially evolved during times of a global drop in atmospheric CO2 content and at relatively hot and dry habitats. During the Late Miocene C4 plants expanded nearly simultaneously at different places in the world, while temperatures declined and global CO2 levels exhibited no corresponding change [1,3]. Our objectives concern the climatic and environmental change of Miocene Southwest Africa between ~14 to ~5 Myrs BP and how these conditions may be linked to the C4 plant expansion. We use a variety of organic geochemical techniques combined with palynology on sediments of ODP Site 1085. The site is situated in the Cape Basin at the south-west African continental margin, within the today's upwelling zone of the Benguela Coastal Current. Miocene sea surface temperature (SST) estimates applying two indices (TEX86 and UK'37) suggest a transition to cooler temperatures from above 27 to 18°C over a time period from ~14 to ~5 Myrs BP, but are different in rate and timing. Increased upwelling leads to cooler SSTs and enhanced marine primary production as implied by a small but clear overall shift in total organic carbon content after 11 Myrs BP. Concurrently, the abundance of both marine cysts and terrestrial pollen and spores increase and the relative contribution river run-off from the nearby Orange River declines, as indicated by the BIT-index (from ~0.8 to <0.1). We connect these findings to a change in strength and the predominant direction of the wind combined with an intensification of the Benguela upwelling current bringing cold, nutrient-rich waters from the South Atlantic and the Antarctic circumpolar current

  19. Neanderthal and Anatomically Modern Human interaction with Abrupt Late Pleistocene Environments - the data is finally good enough to talk about climate change!

    NASA Astrophysics Data System (ADS)

    Blockley, Simon; Schreve, Danielle

    2015-04-01

    The timing and nature of the appearance of Anatomically Modern Humans (AMH) in Europe, their interaction with, and eventual morphological replacement of Neanderthals (despite some shared genetic heritage) has been a matter of intense debate within archaeology for a generation. This period, often termed the Middle to Upper Palaeolithic transition occurs in the latter part of Marine Isotope Stage Three and in recent decades archaeological interest has been complemented by the input of palaeoclimate scientists, over the role of abrupt climate change in this process. This was due to the recognition from ice core and marine proxy archives, in particular, of periods if intense cooling, correlated to the marine record of Heinrich ice rafted debris layers from the Atlantic. As a result of these collaborations between the archaeological and palaeoenvironmental communities various drivers have been proposed for the Middle to Upper Palaeolithic Transition that include: (1) resource competition between two species occupying similar niches; (2) the impact of repeated cycles of Heinrich event cooling, leading to the decline and eventual disappearance of the Neanderthal populations, leaving a new region open for AMH exploitation; and (3) catastrophic impacts of large volcanic eruptions on Neanderthal populations. Attempts to address the above hypotheses have been dogged by the chronological precision available for a number of key archives. The accuracy of many of the radiocarbon ages that underpin the chronology for both Neanderthal and AMH archaeological sites has been questioned1. This has been exacerbated by uncertainties over the influence of variability in the radiocarbon marine reservoir effect on marine palaeoclimate records and a marine dominated radiocarbon calibration curve. Additionally, the counting uncertainties of the master Greenland palaeoclimate archives are also large by this time, meaning palaeoclimate interpretation can be equivocal. However, several research

  20. Environmental change and the natural link between Kazakh Steppe and Northern Eurasia

    NASA Astrophysics Data System (ADS)

    Baibatsha, Adilkhan

    2014-05-01

    In the early to the middle of the Quarternary the southern region of the Kazakh steppe was under the favorable influence of high temperature coming from the depths along faults of mountain ranges and warm moist air mass is nearby at the time of the Indian Ocean. In connection with this region ranges Karatau, western spurs of the Alatau and the southern suburbs Saryarka maintained favorable environmental conditions for life. In periods of prolonged freezing of adjacent territories of Eastern Europe and Western Siberia in the northern regions of the Kazakh steppe developed freezing phenomenon, frozen soil conditions, extended cold snap. The alternation of glaciations with warm interglacial periods caused significant changes of ecological conditions in the environment. In periods of cold weather, caused by glaciation in North Eurasia, animals and primitive people The alternation of cold and warm periods that are favorable and unfavorable conditions for life continues to this day. This life is transitory. Ended and the cold period, which seemed endless. Special cosmic phenomena gave rise to the surface of the earth's unknown in previous epochs of events about 12 thousand years ago, at the turn of the Pleistocene and Holocene epochs of the Quarternary active tectonic movement. Fallen from the sky and the comet's impact with the ground and burning in the atmosphere flows meteor caused a sharp rise in temperature on the surface of the earth. The sudden rise in temperature caused extensive melting of glaciers and permafrost, the flood was on Earth. Eastern Europe and the western part of the Kazakh steppe fully embraced the flood; it flooded the Black Sea and Caspian Sea area. Raising the water level of the seas caused flooding of the isthmus connecting Eurasia and Africa, lost his connection by land between the continents. After a sudden strong warming that caused floods and fires, about 10-9 thousand years BC in the environment established standard conditions with

  1. Environmental changes in Southwest Africa during the Miocene C4 plant expansion

    NASA Astrophysics Data System (ADS)

    Dupont, L. M.; Rommerskirchen, F.; Condon, T.; Mollenhauer, G.; Schefuss, E.

    2009-12-01

    The Late Miocene epoch is characterized by fundamental changes in Earth's climate system: sea-level variability, changes in surface- and deep-water circulation, increase in upwelling intensity along the coasts and turnover in marine and terrestrial biota [1,2]. It is thought that plants using the CO2 concentrating C4 mechanism for photosynthesis potentially evolved during times of a global drop in atmospheric CO2 content and at relatively hot and dry habitats. During the Late Miocene C4 plants expanded nearly simultaneously at different places in the world, while temperatures declined and global CO2 levels exhibited no corresponding change [1,3]. Our objectives concern the climatic and environmental change of Miocene Southwest Africa between ~14 to ~5 Myrs BP and how these conditions may be linked to the C4 plant expansion. We use a variety of organic geochemical techniques combined with palynology on sediments of ODP Site 1085. The site is situated in the Cape Basin at the south-west African continental margin, within the today’s upwelling zone of the Benguela Coastal Current. Miocene sea surface temperature (SST) estimates applying two indices (TEX86 and UK'37) suggest a transition to cooler temperatures from above 27 to 18°C over a time period from ~14 to ~5 Myrs BP, but are different in rate and timing. Increased upwelling leads to cooler SSTs and enhanced marine primary production as implied by a small but clear overall shift in total organic carbon content after 11 Myrs BP. Concurrently, the abundance of both marine cysts and terrestrial pollen and spores increase and the relative contribution river run-off from the nearby Orange River declines, as indicated by the BIT-index (from ~0.8 to <0.1). We connect these findings to a change in strength and the predominant direction of the wind combined with an intensification of the Benguela upwelling current bringing cold, nutrient-rich waters from the South Atlantic and the Antarctic circumpolar current

  2. Holocene sedimentation processes and environmental changes along the Namibian coastline

    NASA Astrophysics Data System (ADS)

    Schüller, Irka; Belz, Lukas; Wilkes, Heinz; Wehrmann, Achim

    2016-04-01

    The regional oceanic and atmospheric circulation patterns strongly control environmental conditions in southern Africa. Changes in the system may have significant consequences on climate and related processes. The hyper arid coast of Namibia is mainly influenced by (1) the cold Benguela upwelling, (2) the Benguela current and (3) the Angola current. The Benguela current transports the cool, upwelling water from south to north and interacts with the warm, contrary flowing Angola current at the Angola-Benguela Front (ABF). Today the ABF is located around the Namibian-Angolan border with minor seasonal changes. Therefore, climate and environment at the Namibian coast are affected by the cold water conditions. It is known evidently that the location of the ABF changed during the Holocene over several latitudes and enabled warm water species to expand their range farther south. Several (paleo-) lagoons (coastal salt pans) exist along the Namibian coastline. Most of them are already barred and filled by longshore sediment transport processes. Tidal flooding and active sedimentation processes are restricted to the southernmost lagoons. Two different types of sediments occur. The northern pans contain well sorted, siliciclastic medium sands. Fine-layered alternation refers to changes in mineral composition. The southern pans are dominated by typical tidal sediments with a high amount of benthic fauna (mainly bivalves and gastropods). At Cape Cross the distinct shift between both facies is documented in the cores. Age determinations of core material prove a very fast sediment filling of the distinct lagoons with high sedimentation rates. However, the age of closure differs from lagoon to lagoon. Northern pan sediments are much older (Cape Cross: ~ 5000 a BP) than southern (Sandwich Bay and Conception Bay: 1800 - 300 a BP). Additional information are supported by river clay deposits (~ 36600 a BP) and fossil reed systems (~ 47900 a BP) in Conception Bay and peat deposits at

  3. Water loss in insects: an environmental change perspective.

    PubMed

    Chown, Steven L; Sørensen, Jesper G; Terblanche, John S

    2011-08-01

    In the context of global environmental change much of the focus has been on changing temperatures. However, patterns of rainfall and water availability have also been changing and are expected to continue doing so. In consequence, understanding the responses of insects to water availability is important, especially because it has a pronounced influence on insect activity, distribution patterns, and species richness. Here we therefore provide a critical review of key questions that either are being or need to be addressed in this field. First, an overview of insect behavioural responses to changing humidity conditions and the mechanisms underlying sensing of humidity variation is provided. The primary sensors in insects belong to the temperature receptor protein superfamily of cation channels. Temperature-activated transient receptor potential ion channels, or thermoTRPs, respond to a diverse range of stimuli and may be a primary integrator of sensory information, such as environmental temperature and moisture. Next we touch briefly on the components of water loss, drawing attention to a new, universal model of the water costs of gas exchange and its implications for responses to a warming, and in places drying, world. We also provide an overview of new understanding of the role of the sub-elytral chamber for water conservation, and developments in understanding of the role of cuticular hydrocarbons in preventing water loss. Because of an increasing focus on the molecular basis of responses to dehydration stress we touch briefly on this area, drawing attention to the role of sugars, heat shock proteins, aquaporins, and LEA proteins. Next we consider phenotypic plasticity or acclimation responses in insect water balance after initial exposures to altered humidity, temperature or nutrition. Although beneficial acclimation has been demonstrated in several instances, this is not always the case. Laboratory studies show that responses to selection for enhanced ability to

  4. Global environmental change: local perceptions, understandings, and explanations

    PubMed Central

    Pyhälä, Aili; Fernández-Llamazares, Álvaro; Lehvävirta, Hertta; Byg, Anja; Ruiz-Mallén, Isabel; Salpeteur, Matthieu; Thornton, Thomas F.

    2016-01-01

    Global environmental change (GEC) is an increasingly discussed phenomenon in the scientific literature as evidence of its presence and impacts continues to grow. Yet, while the documentation of GEC is becoming more readily available, local perceptions of GEC— particularly in small-scale societies—and preferences about how to deal with it, are still largely overlooked. Local knowledge and perceptions of GEC are important in that agents make decisions (including on natural resource management) based on individual perceptions. We carried out a systematic literature review that aims to provide an exhaustive state-of-the-art of the degree to and manner in which the study of local perceptions of change are being addressed in GEC research. We reviewed 126 articles found in peer-reviewed journals (between 1998 and 2014) that address local perceptions of GEC. We used three particular lenses of analysis that are known to influence local perceptions, namely (i) cognition, (ii) culture and knowledge, and (iii) possibilities for adaptation.We present our findings on the geographical distribution of the current research, the most common changes reported, perceived drivers and impacts of change, and local explanations and evaluations of change and impacts. Overall, we found the studies to be geographically biased, lacking methodological reporting, mostly theory based with little primary data, and lacking of indepth analysis of the psychological and ontological influences in perception and implications for adaptation. We provide recommendations for future GEC research and propose the development of a “meta-language” around adaptation, perception, and mediation to encourage a greater appreciation and understanding of the diversity around these phenomena across multiple scales, and improved codesign and facilitation of locally relevant adaptation and mitigation strategies. PMID:27695479

  5. Global environmental change: local perceptions, understandings, and explanations.

    PubMed

    Pyhälä, Aili; Fernández-Llamazares, Álvaro; Lehvävirta, Hertta; Byg, Anja; Ruiz-Mallén, Isabel; Salpeteur, Matthieu; Thornton, Thomas F

    2016-09-01

    Global environmental change (GEC) is an increasingly discussed phenomenon in the scientific literature as evidence of its presence and impacts continues to grow. Yet, while the documentation of GEC is becoming more readily available, local perceptions of GEC- particularly in small-scale societies-and preferences about how to deal with it, are still largely overlooked. Local knowledge and perceptions of GEC are important in that agents make decisions (including on natural resource management) based on individual perceptions. We carried out a systematic literature review that aims to provide an exhaustive state-of-the-art of the degree to and manner in which the study of local perceptions of change are being addressed in GEC research. We reviewed 126 articles found in peer-reviewed journals (between 1998 and 2014) that address local perceptions of GEC. We used three particular lenses of analysis that are known to influence local perceptions, namely (i) cognition, (ii) culture and knowledge, and (iii) possibilities for adaptation.We present our findings on the geographical distribution of the current research, the most common changes reported, perceived drivers and impacts of change, and local explanations and evaluations of change and impacts. Overall, we found the studies to be geographically biased, lacking methodological reporting, mostly theory based with little primary data, and lacking of indepth analysis of the psychological and ontological influences in perception and implications for adaptation. We provide recommendations for future GEC research and propose the development of a "meta-language" around adaptation, perception, and mediation to encourage a greater appreciation and understanding of the diversity around these phenomena across multiple scales, and improved codesign and facilitation of locally relevant adaptation and mitigation strategies.

  6. Pleistocene plants from North Carolina

    USGS Publications Warehouse

    Berry, Edward Wilber

    1926-01-01

    The field work upon which this report is based was done in 1906 and 1907 as a part of the cooperative study of the Atlantic Coastal Plain, under the direction of the late William Bullock Clark. Associated with the writer in this work were L. W. Stephenson, B. L. Miller, Jr., and J. E. Pogue. Preliminary accounts of the plants collected were published in 1907 and 1909. As has been frequently emphasized, the study of the Pleistocene floras in this country is in an exceedingly backward state as measured by the volume and precision of our knowledge of Pleistocene floras in Europe. Researches in Pleistocene geology in North America have been confined almost entirely to glaciology, and the problem of the correlation of the glacial deposits with those outside the glaciated area has not been solved, nor is there any general agreement regarding the genesis of the Pleistocene deposits south of the terminal moraines. The present account of what is known of the Pleistocene flora of North Carolina and the conclusions that may be legitimately derived from it is offered in the hope that it may stimulate an interest in a neglected field of research and form a small part of the evidence upon which to base future more comprehensive conclusions and generalizations. A word of explanation regarding the illustrations is required. Nearly all of them have been made from leaves preserved as carbonaceous films in the peaty clays. These specimens were carefully washed out, and blue prints were made directly from them. Outlines and as much of the venation as could be seen were inked on the blue prints, which were then bleached. This procedure made it possible to handle a much larger amount of material and prevented any possible damage to the exceedingly fragile specimens, which were mounted on cards or between glass. The accompanying drawings were made from tracings of the original nature prints.

  7. Soil carbon responses to environmental change across temporal scales

    NASA Astrophysics Data System (ADS)

    Sierra, Carlos; Müller, Markus; Metzler, Holger

    2016-04-01

    Different biotic and abiotic factors modify the rates of soil carbon cycling at a variety of temporal scales, posing challenges in determining appropriate model abstractions to represent soil carbon dynamics in the context of global environmental change. Although a large variety of models of soil organic matter dynamics have been proposed previously, it is difficult to compare different model structures and their scale of application. We present here a mathematical framework that can be used to synthesize models with different structure, i.e. number of distinctive pools, their cycling rates and their connection. This framework can also be used to identify the scale of operability of a model and how carbon stocks and respiration fluxes would respond to external perturbations. In this contribution, we present the main concepts behind our mathematical framework and how through eigenvalue analyses we can identify the scale of operability of a model. We also present an analysis of the potential sensitivity of soil carbon stocks to changes in temperature and moisture, and identify regions with larger sensitivities to climate change. Although different models provide very diverse responses, we predict larger sensitivities of soil C stocks in humid tropical regions to increases in temperature and decreases in soil moisture.

  8. Predicting effects of environmental change on a migratory herbivore

    USGS Publications Warehouse

    Stillman, R A; Wood, K A; Gilkerson, Whelan; Elkinton, E; Black, J. M.; Ward, David H.; Petrie, M.

    2015-01-01

    for which birds were disturbed. We discuss the consequences of these predictions for Black Brant conservation. A wide range of migratory species responses are expected in response to environmental change. Process-based models are potential tools to predict such responses and understand the mechanisms which underpin them.

  9. Direct isotopic evidence for subsistence variability in Middle Pleistocene Neanderthals (Payre, southeastern France)

    NASA Astrophysics Data System (ADS)

    Bocherens, Hervé; Díaz-Zorita Bonilla, Marta; Daujeard, Camille; Fernandes, Paul; Raynal, Jean-Paul; Moncel, Marie-Hélène

    2016-12-01

    The site of Payre (SE France) is presented as a case study to decipher possible changes in subsistence and land-use strategies during the middle Pleistocene in Europe. This study applies carbon and oxygen isotopic data (δ13C and δ18O) in dental tooth enamel from four distinct Middle Pleistocene Neanderthals coming from two phases of occupation. This allows us to test if these different Neanderthals were similar in their subsistence strategies and mobility during their childhood, and to compare them with terrestrial predators and to herbivores dwelling in different areas around the cave. The results show that Neanderthals were exploiting the environment differently over time in the absence of a significant environmental change. This change of environment exploitation coincides with different durations of occupation. The age of the individuals allows us to discuss the mobility of young Neanderthals and the topographies they lived on before arriving in the cave. The combination of results obtained from various approaches throws a new light on the investigation of Neanderthal ecosystem and land-use patterns during the Early Middle Palaeolithic in Southeastern France.

  10. EDITORIAL: Northern Hemisphere high latitude climate and environmental change

    NASA Astrophysics Data System (ADS)

    Groisman, Pavel; Soja, Amber

    2007-10-01

    High Northern Hemisphere latitudes are undergoing rapid and significant change associated with climate warming. Climatic change in this region interacts with and affects the rate of the global change through atmospheric circulation, biogeophysical, and biogeochemical feedbacks. Changes in the surface energy balance, hydrologic cycle, and carbon budget feedback to regional and global weather and climate systems. Two-thirds of the Northern Hemisphere high latitude land mass resides in Northern Eurasia (~20% of the global land mass), and this region has undergone sweeping socio-economic change throughout the 20th century. How this carbon-rich, cold region component of the Earth system functions as a regional entity and interacts with and feeds back to the greater global system is to a large extent unknown. To mitigate the deficiencies in understanding these feedbacks, which may in turn hamper our understanding of the global change rates and patterns, an initiative was formed. Three years ago the Northern Eurasia Earth Science Partnership Initiative (NEESPI) was established to address large-scale and long-term manifestations of climate and environmental change in this region. The NEESPI Science Plan and its Executive Summary have been published at the NEESPI web site (neespi.org). Since 2004, NEESPI participants have been able to seed several waves of research proposals to international and national funding agencies and institutions and also contribute to the International Polar Year. Currently, NEESPI is widely recognized and endorsed by several Earth System Science Partnership (ESSP) programmes and projects: the International Geosphere and Biosphere Programme, the World Climate Research Programme through the Global Energy and Water Cycle Experiment and Climate and Cryosphere Projects, the Global Water System Project, Global Carbon Project, Global Land Project, and the Integrated Land Ecosystem—Atmosphere Processes Study. Through NEESPI, more than 100 individually

  11. Reconstructing Mid-Pleistocene paleovegetation and paleoclimate in the Golan Heights using the δ(13)C values of modern vegetation and soil organic carbon of paleosols.

    PubMed

    Hartman, Gideon

    2011-04-01

    The Golan Heights borders the Upper Jordan Valley on its eastern side and likely served as a prime foraging area for hominin groups that inhabited the Upper Jordan Valley during the Mid-Pleistocene. This study tests the hypothesis that Mid-Pleistocene climate in the Golan region was similar to that of the present day. Carbon isotope composition of present day plant communities and soil organic carbon from the Golan were compared to those of paleosols from Nahal Orvim to reconstruct Mid-Pleistocene paleoclimatic conditions. After correcting the paleosol values for recent changes in atmospheric carbon isotope values and potential biodegradation, the isotopic results show a strong similarity to those of present day local plants and soils. These results indicate that during the Mid-Pleistocene, the Golan was dominated by C(3) vegetation, shared similar climatic conditions with the present day, and displayed long-term environmental stability. The span of time of paleosol formation is unknown and might cover multiple climatic episodes; thus, although short climatic fluctuations may have occurred, their impact was not substantial enough to be detected in the Nahal Orvim paleosols. This study concludes that the Golan slopes provided hominins and large grazers with a reliable and highly nutritious foraging area that complemented the Jordan Valley riparian ecosystem.

  12. Environmental monitoring in peat bog areas by change detection methods

    NASA Astrophysics Data System (ADS)

    Michel, Ulrich; Mildes, Wiebke

    2016-10-01

    Remote sensing image analysis systems and geographic information systems (GIS) show great promise for the integration of a wide variety of spatial information supporting tasks such as urban and regional planning, natural resource management, agricultural studies and topographic or thematic mapping. Current and future remote sensing programs are based on a variety of sensors that will provide timely and repetitive multisensor earth observation on a global scale. GIS offer efficient tools for handling, manipulating, analyzing and presenting spatial data that are required for sensible decision making in various areas. The Environmental Monitoring project may serve as a convincing example of the operational use of integrated GIS/remote sensing technologies. The overall goal of the project is to assess the capabilities of satellite remote sensing for the analysis of land use changes, especially in moor areas. These areas are recognized as areas crucial to the mission of the Department of Environment and, therefore, to be placed under an extended level of protection. It is of critical importance, however, to have accurate and current information about the ecological and economic state of these sensitive areas. In selected pasture and moor areas, methods for multisensor data fusion have being developed and tested. The results of this testing show which techniques are useful for pasture and moor monitoring at an operational level. A hierarchical method is used for extracting bog land classes with respect to the environmental protection goals. A highly accurate classification of the following classes was accomplished: deciduous- and mixed forest, coniferous forest, water, very wet areas, meadowland/farmland with vegetation, meadowland/farmland with partly vegetation, meadowland/ farmland without vegetation, peat quarrying with maximum of 50% vegetation, de- and regeneration stages. In addition, a change detection analysis is performed in comparison with the existing

  13. Microbial Habitability and Pleistocene Aridification of the Asian Interior

    NASA Astrophysics Data System (ADS)

    Wang, Jiuyi; Lowenstein, Tim K.; Fang, Xiaomin

    2016-06-01

    Fluid inclusions trapped in ancient halite can contain a community of halophilic prokaryotes and eukaryotes that inhabited the surface brines from which the halite formed. Long-term survival of bacteria and archaea and preservation of DNA have been reported from halite, but little is known about the distribution of microbes in buried evaporites. Here we report the discovery of prokaryotes and single-celled algae in fluid inclusions in Pleistocene halite, up to 2.26 Ma in age, from the Qaidam Basin, China. We show that water activity (aw), a measure of water availability and an environmental control on biological habitability in surface brines, is also related to microbe entrapment in fluid inclusions. The aw of Qaidam Basin brines progressively decreased over the last ˜1 million years, driven by aridification of the Asian interior, which led to decreased precipitation and water inflow and heightened evaporation rates. These changes in water balance produced highly concentrated brines, which reduced the habitability of surface lakes and decreased the number of microbes trapped in halite. By 0.13 Ma, the aw of surface brines approached the limits tolerated by halophilic prokaryotes and algae. These results show the response of microbial ecosystems to climate change in an extreme environment, which will guide future studies exploring deep life on Earth and elsewhere in the Solar System.

  14. Late Pleistocene and Holocene Hydroclimate Variability in the Tropical Andes from Alpine Lake Sediments, Cordillera de Mérida, Venezuela

    NASA Astrophysics Data System (ADS)

    Larsen, D. J.; Abbott, M. B.; Polissar, P. J.

    2014-12-01

    The tropics play a major role in the global hydrologic cycle and changes to tropical rainfall patterns have critical implications for water resources and ecosystem dynamics over large geographic scales. In tropical South America, late Pleistocene and Holocene precipitation variability has been documented in geologic records and associated with numerous external and internal variables, including changes in summer insolation, South American summer monsoon strength, Pacific Ocean sea surface temperatures, continental moisture recycling, and other climate processes. However, there are few records from the northern hemisphere tropical Americas, a key region for understanding interhemispheric linkages and the drivers of tropical hydroclimate variability. Here, we present a ~13 ka record of coupled hydroclimate and environmental changes from Laguna Brava, a small (~0.07 km2), hydrologically closed lake basin situated at 2400 m asl in the Cordillera de Mérida, Venezuela. Sediment cores collected from varying water depths and proximity to shore are placed in a chronologic framework using radiocarbon ages from terrestrial macrofossils, and analyzed for a suite of physical, bulk geochemical, and stable isotopic parameters. Compound specific hydrogen isotope (D/H) measurements of terrestrial plant waxes (long-chain n-alkanes) show a sharp increase in the late Pleistocene, followed by a long-term trend toward more negative values that suggest a ~20‰ decrease in the D/H ratios of South American tropical precipitation during the Holocene. This pattern is consistent in sign and magnitude to other South American precipitation reconstructions from both hemispheres, indicating interhemispheric similarities in tropical hydroclimate variability. Superimposed on this continent-scale trend are changes in moisture balance and environmental conditions in the Venezuelan Andes. We reconstruct these parameters at Laguna Brava at multidecadal and centennial resolution and evaluate this

  15. Environmental Changes in the pre-Messinian Mediterranean Region

    NASA Astrophysics Data System (ADS)

    Mayser, J. P.; Marzocchi, A.; Lunt, D. J.; Pancost, R. D.; Sierro, F. J.; Flecker, R.

    2015-12-01

    The Messinian Salinity Crisis (MSC) is an extreme event which occurred in the Mediterranean Basin at the end of the Miocene (5.97 to 5.33 Ma) resulting in thick evaporite deposits. There is evidence of restriction of the Atlantic-Mediterranean corridor several million years before the first evaporites. These pre-MSC successions are dominated by precession-controlled lithological variations which are putative responses to changing fluvial runoff. Recent climate simulations indicate that runoff into the Eastern Mediterranean is influenced by monsoonal precipitation from the North African continent. The Sorbas Basin in Spain and the Pissouri Section on Cyprus both contain pre-MSC successions from the margins of the Mediterranean Basin. We analysed biomarkers in conjunction with existing faunal records to understand whether simulated runoff changes were manifested in the sedimentological record and organic matter assemblages. This multi-proxy dataset allows us to compare the environmental evolution of the western vs. eastern basins prior to the MSC and allows us to test both climate models for Messinian climate variabitly and conceptual models for sedimentation. In the Sorbas Basin, pronounced orbital changes in faunal assemblages reflect Mediterrannean influences into the local Sorbas system; however, these are not manifested in biomarker assemblages, which are likely governed by more local hydrological processes, which in the Western Mediterranean lacked a strong precessional control. In the Pissouri Basin, however, terrigeous OM inputs sources exhibit strong orbital variations, suggesting a close link to precessionally driven changes in rainfall. Together, these results validate the sapropel formation hypothesis in the Mediterranean and confirm a strong precessional control on the African monsoon during the late Miocene; however, they also reveal the complex controls on the hydrology and sedimentology of marginal Mediterranean basins, such as the Sorbas Basin.

  16. Surface monitoring measurements of materials on environmental change conditions

    NASA Astrophysics Data System (ADS)

    Tornari, Vivi; Bernikola, Eirini; Bellendorf, Paul; Bertolin, Chiara; Camuffo, Dario; Kotova, Lola; Jacobs, Daniela; Zarnic, Roko; Rajcic, Vlatka; Leissner, Johanna

    2013-05-01

    Climate Change is one of the most critical global challenges of our time and the burdened cultural heritage of Europe is particularly vulnerable to be left unprotected. Climate for Culture2 project exploits the damage impact of climate change on cultural heritage at regional scale. In this paper the progress of the study with in situ measurements and investigations at cultural heritage sites throughout Europe combined with laboratory simulations is described. Cultural works of art are susceptible to deterioration with environmental changes causing imperceptibly slow but steady accumulation of damaging effects directly impacted on structural integrity. Laser holographic interference method is employed to provide remote non destructive field-wise detection of the structural differences occurred as climate responses. The first results from climate simulation of South East Europe (Crete) are presented. A full study in regards to the four climate regions of Europe is foreseen to provide values for development of a precise and integrated model of thermographic building simulations for evaluation of impact of climate change. Development of a third generation user interface software optimised portable metrology system (DHSPI II) is designed to record in custom intervals the surface of materials witnessing reactions under simulated climatic conditions both onfield and in laboratory. The climate conditions refer to real data-loggers readings representing characteristic historical building in selected climate zones. New generation impact sensors termed Glass Sensors and Free Water Sensors are employed in the monitoring procedure to cross-correlate climate data with deformation data. In this paper results from the combined methodology are additionally presented.

  17. Applications of Satellite Geodesy in Environmental and Climate Change

    NASA Astrophysics Data System (ADS)

    Yang, Qian

    Satellite geodesy plays an important role in earth observation. This dissertation presents three applications of satellite geodesy in environmental and climate change. Three satellite geodesy techniques are used: high-precision Global Positioning System (GPS), the Gravity Recovery and Climate Experiment (GRACE) and Interferometric Synthetic Aperture Radar (InSAR). In the first study, I use coastal uplift observed by GPS to study the annual changes in mass loss of the Greenland ice sheet. The data show both spatial and temporal variations of coastal ice mass loss and suggest that a combination of warm atmospheric and oceanic condition drove these variations. In the second study, I use GRACE monthly gravity change estimates to constrain recent freshwater flux from Greenland. The data show that Arctic freshwater flux started to increase rapidly in the mid-late 1990s, coincident with a decrease in the formation of dense Labrador Sea Water, a key component of the deep southward return flow od the Atlantic Meridional Overturning Circulation (AMOC). Recent freshening of the polar oceans may be reducing formation of Labrador Sea Water and hence may be weakening the AMOC. In the third study, I use InSAR to monitor ground deformation caused by CO2 injection at an enhanced oil recovery site in west Texas. Carbon capture and storage can reduce CO 2 emitted from power plants, and is a promising way to mitigate anthropogenic warming. From 2007 to 2011, ~24 million tons of CO2 were sequestered in this field, causing up to 10 MPa pressure buildup in a reservoir at depth, and surface uplift up to 10 cm. This study suggests that surface displacement observed by InSAR is a cost-effective way to estimate reservoir pressure change and monitor the fate of injected fluids at waste disposal and CO2 injection sites.

  18. Environmental change and the carbon balance of Amazonian forests.

    PubMed

    Aragão, Luiz E O C; Poulter, Benjamin; Barlow, Jos B; Anderson, Liana O; Malhi, Yadvinder; Saatchi, Sassan; Phillips, Oliver L; Gloor, Emanuel

    2014-11-01

    Extreme climatic events and land-use change are known to influence strongly the current carbon cycle of Amazonia, and have the potential to cause significant global climate impacts. This review intends to evaluate the effects of both climate and anthropogenic perturbations on the carbon balance of the Brazilian Amazon and to understand how they interact with each other. By analysing the outputs of the Intergovernmental Panel for Climate Change (IPCC) Assessment Report 4 (AR4) model ensemble, we demonstrate that Amazonian temperatures and water stress are both likely to increase over the 21st Century. Curbing deforestation in the Brazilian Amazon by 62% in 2010 relative to the 1990s mean decreased the Brazilian Amazon's deforestation contribution to global land use carbon emissions from 17% in the 1990s and early 2000s to 9% by 2010. Carbon sources in Amazonia are likely to be dominated by climatic impacts allied with forest fires (48.3% relative contribution) during extreme droughts. The current net carbon sink (net biome productivity, NBP) of +0.16 (ranging from +0.11 to +0.21) Pg C year(-1) in the Brazilian Amazon, equivalent to 13.3% of global carbon emissions from land-use change for 2008, can be negated or reversed during drought years [NBP = -0.06 (-0.31 to +0.01) Pg C year(-1) ]. Therefore, reducing forest fires, in addition to reducing deforestation, would be an important measure for minimizing future emissions. Conversely, doubling the current area of secondary forests and avoiding additional removal of primary forests would help the Amazonian gross forest sink to offset approximately 42% of global land-use change emissions. We conclude that a few strategic environmental policy measures are likely to strengthen the Amazonian net carbon sink with global implications. Moreover, these actions could increase the resilience of the net carbon sink to future increases in drought frequency.

  19. High resolution studies of gully erosion, sedimentation processes, and land use changes since the late Pleistocene and future trajectories in the Kazimierz Dolny area (Nałęczów Plateau, SE-Poland)

    NASA Astrophysics Data System (ADS)

    Dotterweich, M.; Rodzik, J.; Zgłobicki, W.; Schmitt, A.; Schmidtchen, G.; Bork, H. R.

    2012-04-01

    This paper presents the results of 30 years of research on the Doły Podmularskie gully system (catchment 0.35 km2 in size), which is situated in the south-western part of the loess-covered Nałęczów Plateau in SE-Poland. Detailed topographic, stratigraphic and pedologic investigations, and monitoring of a tributary gully (gully area: 0.7 ha, catchment: 2.5 ha), combined with historical, archaeological and palaeoecological records reveal a long and complex history in terms of the temporal and spatial extent and the impact of land use on gully erosion, and the long-term feed-back mechanisms between land use changes and natural processes since the end of the Pleistocene are also expressed. Phases of gully erosion and subsequent filling occurred in the Bronze Age and around the 10th to 11th century. The most severe deepening and expansion of the gully took place in the 17th century. The results also show that field structures and land use intensity had a significant influence on the frequency and magnitude of run-off, soil erosion, piping, and landslide events. The last significant erosion phase started in the mid-19th century with renewed headward retreatment and down-cutting into older gully fills. Today, most of the catchment is either forested or the land is covered in berry shrubs. In the future, the area will continue to produce sediments, because of the steep slopes and because there are still areas of bare soil with a low resistance to erosion, a legacy from past land uses, which will remain a factor affecting soil erosion and sedimentation processes in the future. This study is an example of how important it is to observe and understand slow geomorphologic processes, changes and rare extreme events in the light of land use changes when investigating long-term human-environment interactions.

  20. Mangrove response to environmental change in Australia's Gulf of Carpentaria.

    PubMed

    Asbridge, Emma; Lucas, Richard; Ticehurst, Catherine; Bunting, Peter

    2016-04-20

    Across their range, mangroves are responding to coastal environmental change. However, separating the influence of human activities from natural events and processes (including that associated with climatic fluctuation) is often difficult. In the Gulf of Carpentaria, northern Australia (Leichhardt, Nicholson, Mornington Inlet, and Flinders River catchments), changes in mangroves are assumed to be the result of natural drivers as human impacts are minimal. By comparing classifications from time series of Landsat sensor data for the period 1987-2014, mangroves were observed to have extended seawards by up to 1.9 km (perpendicular to the coastline), with inland intrusion occurring along many of the rivers and rivulets in the tidal reaches. Seaward expansion was particularly evident near the mouth of the Leichhardt River, and was associated with peaks in river discharge with LiDAR data indicating distinct structural zones developing following each large rainfall and discharge event. However, along the Gulf coast, and particularly within the Mornington Inlet catchment, the expansion was more gradual and linked to inundation and regular sediment supply through freshwater input. Landward expansion along the Mornington Inlet catchment was attributed to the combined effects of sea level rise and prolonged periods of tidal and freshwater inundation on coastal lowlands. The study concluded that increased amounts of rainfall and associated flooding and sea level rise were responsible for recent seaward and landward extension of mangroves in this region.

  1. Using GPS and absolute gravity observations to separate the effects of present-day and Pleistocene ice-mass changes in South East Greenland

    NASA Astrophysics Data System (ADS)

    van Dam, T.; Francis, O.; Wahr, J.; Khan, S. A.; Bevis, M.; van den Broeke, M. R.

    2017-02-01

    Measurements of vertical crustal uplift from bedrock sites around the edge of the Greenland ice sheet (GrIS) can be used to constrain present day mass loss. Interpreting any observed crustal displacement around the GrIS in terms of present day changes in ice is complicated, however, by the glacial isostatic adjustment (GIA) signal. With GPS observations alone, it is impossible to separate the uplift driven by present day mass changes from that due to ice mass changes in the past. Wahr et al. (1995) demonstrated that viscoelastic surface displacements were related to the viscoelastic gravity changes through a proportionality constant that is nearly independent of the choice of Earth viscosity or ice history model. Thus, by making measurements of both gravity and surface motion at a bedrock site, the viscoelastic effects could be removed from the observations and we would be able to constrain present day ice mass changes. Alternatively, we could use the same observations of surface displacements and gravity to determine the GIA signal. In this paper, we extend the theory of Wahr et al. (1995) by introducing a constant, Z, that represents the ratio between the elastic changes in gravity and elastic uplift at a particular site due to present day mass changes. Further, we combine 20 yrs of GPS observations of uplift with eight absolute gravity observations over the same period to determine the GIA signal near Kulusuk, a site on the southeastern side of the GrIS, to experimentally demonstrate the theory. We estimate that the GIA signal in the region is 4.49 ± 1.44mm/yr and is inconsistent with most previously reported model predictions that demonstrate that the GIA signal here is negative. However, as there is very little in situ data to constrain the GIA rate in this part of Greenland, the Earth model or the ice history reconstructions could be inaccurate (Khan et al., 2016). Improving the estimate of GIA in this region of Greenland will allow us to better determine

  2. Drivers and Dynamics of Global Environmental Change in Southern Africa

    NASA Astrophysics Data System (ADS)

    Jewitt, Graham; Munishi, Subira; Kunz, Richard; Viola, Paula

    2010-05-01

    Africa's potential to provide food, fuel, fibre and fodder for future global food and energy security has made it a target for a myriad investors from developed and developing countries alike. In many places, land grants and purchases have led to the establishment of huge monoculture production areas for food, fuel, fibre (maize, sugar cane, jatropha, plantation forestry etc) often preceded by deforestation and large scale utilisation and modification of available water resources. This coupled with the likelihood of rapid urbanisation in Africa over the next forty years and associated impacts linked to the high concentrations of inhabitants utilising and ultimately degrading available natural resources (e.g. wood for charcoal; water quality) have made Africa's ecosystems and people amongst the most vulnerable to global environmental change. Key questions that arise are how available scientific knowledge can best be utilized to reduce this vulnerability, where key gaps in knowledge in understanding the inter-linkages between societal needs and Food- Fibre-Energy-Water supply exist and how to best address the necessary complexity of considering these at different spatial and temporal scales. Drawing on the Ecosystem Goods and Services approach, we present key messages from ongoing research activities in South Africa, Swaziland, Mozambique and Tanzania and report on progress in applying management tools and systems to support decision making in these areas where development needs are critical. We also highlight lessons drawn from situations where unintended consequences have resulted from well meaning or politically expedient initiatives linked to large donor or foreign investment schemes, such as "outgrower" programmes, and where major environmental damage and ultimately the permanent loss of productivity of some landscapes has occurred.

  3. Stable-Isotope Perspectives on Holocene Environmental Change at Archaeological Sites in the Middle Tanana Valley, Interior Alaska

    NASA Astrophysics Data System (ADS)

    Johnson, W. C.; Gaines, E. P.

    2010-12-01

    Summer of 2009, Colorado State University Center for Environmental Management of Military Lands conducted test excavations of 29 prehistoric archaeological sites situated on a loess-mantled morainal ridge complex within the Jarvis Creek valley of the Tanana River system at Fort Wainwright in Interior Alaska. Initial loess deposition on the moraines began about 13,000 cal yr BP, with subsequent long-term, nomadic occupation of the area occurring from 9,500 to 1,060 cal yr BP. An array of data were extracted from bulk-sediment samples and used to assess past environmental conditions. Parameters and approaches used to generate these data included stable carbon isotope ratios, magnetic susceptibility, biogenic opal analysis, detrital charcoal content, quantitative color (L*a*b), and particle-size distribution. Stable carbon isotope trends, in combination with the other environmental proxy data, document major environmental changes. Data from the glacial till-loess transition and lower silt mantle indicate that the area was cold and slightly mesic, and dominated by treeless C3-dominated grassland immediately after the terminal Pleistocene glacial retreat (~12,700 cal yr BP). A dearth of particulate charcoal and charred phytoliths from sediments of this period suggests a minor role for fire, e.g., only localized, small fires. Cold, treeless environmental conditions continued throughout the Early Holocene (~12,000-7,000 cal yr BP), though it was more mesic than earlier. Middle Holocene (~7000-5000 cal yr BP) data display a shift in C3 grass species (increased δ13C values), the appearance of a shrub component to the plant community, significant surface stability, and more widespread fire occurrence. Picea glauca (white spruce) and Alnus sp. (alder) appear in the later parts of the Middle Holocene, and charcoal concentration increases. The Late Holocene (since ~5,000 cal yr BP) witnessed a decline in P. glauca by about 50%, a tenfold increase in Alnus, and the appearance

  4. A record of barite accumulation rate for marine export productivity changes in the tropical Indian Ocean during the Mid-Pliocene--Early-Pleistocene transition

    NASA Astrophysics Data System (ADS)

    Zhou, Liping; Ma, Zhongwu; Ding, Xuan

    2016-04-01

    One of the most interesting features in the marine oxygen isotope records is the gradual shift towards heavier 18O from the Mid-Pliocene, which ends with the initiation of Northern Hemisphere glaciation (NHG) around 2.7 Ma. The lack of significant change in sea surface temperature in the tropical Indian Ocean as revealed in the previous studies does not rule out their possible contributions to this dramatic climate change during the Mid-Pliocene transition. Changing circulation systems in the region will control the supply of nutrients for the water masses which in turn determine the marine productivity. In the areas of high productivity, ocean export productivity may potentially provide a mechanism of CO2 draw-down into the deep ocean, through which contributing to the lowering of the global temperature. In this study, we present a record of barite accumulation rate (BAR) for DSDP Site 214 drilled on the Ninetyeast Ridge. Here we use the marine barite, which is formed during the decay of organism in the twilight zone, as a proxy for ocean export productivity. Our results show that the BAR of Site 214 varies between 0.25 and 1.25 mg/cm2/kyr during the period between 4 Ma and 2 Ma. Five intervals of increased BAR from 3.6 Ma to 2.4 Ma are identified with the most distinct peak centred around 3 Ma. The overall pattern does not follow either the oxygen isotope record for the Site or the sea surface temperature and subsurface temperature reconstructed with the Mg/Ca of foraminifera. This suggests that regional changes in ocean circulation and water masses may have played more important role than temperature in controlling the productivity change in the tropical Indian Ocean. The relative higher productivity around 3 Ma may imply a biogenetic process towards the intensification of NHGs.

  5. Staff attitude changes after environmental changes on a ward for psychogeriatric patients.

    PubMed

    Ingstad, P J; Götestam, K G

    1987-01-01

    On a ward for chronic elderly patients, mostly senile demented patients, several environmental changes were performed to improve the patients' behaviors. Before and after these changes, the staff (N = 12) were asked about their attitudes in relation to different issues, according to a semantic differential scheme. The semantic differential scheme consisted (apart from six distractor pairs) of the following semantic pairs: (a) negative-positive, (b) valueless-valuable, (c) bad-good, (d) onesided-manysided, (e) unimportant-important, and (f) stupid-smart. The object sentences tested with this semantic differential scheme were (1) cleaning the ward, (2) the patients' meals, (3) dressing the patients, and (4) social interaction with patients. The results showed significant positive changes in staff attitudes towards the patients in the three last object sentences. These also corresponded to the interventions made in the environmental program, whereas "cleaning the ward" was not really changed during the program. It is concluded that improvements in patient behaviors on the ward has important positive effects also on the staff attitudes.

  6. Late Pleistocene and Holocene paleolimnology of two mountain lakes in western Tasmania.

    USGS Publications Warehouse

    Platt, Bradbury J.

    1986-01-01

    The analysis of diatoms from two lake-sediment cores from southwestern Tasmania that span the Pleistocene-Holocene boundary provides insight about paleolimnological and paleoclimatic change in this region. Both Lake Vera and Eagle Tarn have lacustrine records that begin about 12 000 yr ago. Both lakes have had similar limnological histories. Each appears to have been larger and more alkaline 12 000 yr ago and both became shallower through time. Fossil diatom assemblages about 11 000 yr old indicate shallow- water environments that fluctuated in pH, and between dilute and possibly slightly saline hydrochemical conditions. Beginning 11 500 yr ago, limnological conditions of shallow, dilute water of neutral pH prevailed, indicating reduction of moisture stress. A subsequent transition to diatom assemblages indicative of acidic conditions about 10 000 yr ago parallels the establishment of rain-forest vegetation and essentially modern climatic conditions with excess precipitation over evaporation. Changes at these separate and distinctive sites suggests a regional paleoclimatic cause rather than local environmental effects. Latest Pleistocene climates were apparently more continental and drier than Holocene climates in southwestern Tasmania.-from Author

  7. Timing and dynamics of Late Pleistocene mammal extinctions in southwestern Australia.

    PubMed

    Prideaux, Gavin J; Gully, Grant A; Couzens, Aidan M C; Ayliffe, Linda K; Jankowski, Nathan R; Jacobs, Zenobia; Roberts, Richard G; Hellstrom, John C; Gagan, Michael K; Hatcher, Lindsay M

    2010-12-21

    Explaining the Late Pleistocene demise of many of the world's larger terrestrial vertebrates is arguably the most enduring and debated topic in Quaternary science. Australia lost >90% of its larger species by around 40 thousand years (ka) ago, but the relative importance of human impacts and increased aridity remains unclear. Resolving the debate has been hampered by a lack of sites spanning the last glacial cycle. Here we report on an exceptional faunal succession from Tight Entrance Cave, southwestern Australia, which shows persistence of a diverse mammal community for at least 100 ka leading up to the earliest regional evidence of humans at 49 ka. Within 10 millennia, all larger mammals except the gray kangaroo and thylacine are lost from the regional record. Stable-isotope, charcoal, and small-mammal records reveal evidence of environmental change from 70 ka, but the extinctions occurred well in advance of the most extreme climatic phase. We conclude that the arrival of humans was probably decisive in the southwestern Australian extinctions, but that changes in climate and fire activity may have played facilitating roles. One-factor explanations for the Pleistocene extinctions in Australia are likely oversimplistic.

  8. Reconstructing the palaeoenvironments of the early Pleistocene mammal faunas from the pollen preserved on fossil bones

    NASA Astrophysics Data System (ADS)

    Ravazzi, Cesare; Pini, Roberta; Breda, Marzia

    2009-12-01

    We carried out a systematic investigation on the pollen content of sediment adhering to skeletal elements of large mammals which originate from the long lacustrine record of Leffe (Early Pleistocene of the Italian Alps). Three local faunas were discovered during mining activities along the intermediate part (spanning from 1.5 to 0.95 Ma) of the basin succession. The excellent pollen preservation allowed testing the reproducibility of the pollen signal from single skeletons. A clear palaeoenvironmental patterning, consistent with the ecological preferences of the considered mammal species, emerged from the canonical correspondence analysis of pollen types diagnostic for vegetation communities. Edaphic factors related to seasonal river activity changes and to the development of swamp forests in the riverbanks are significantly associated to the occurrences of Hippopotamus cf. antiquus, whereas finds of Mammuthus meridionalis belong to fully forested landscapes dominated by conifer or mixed forests of oceanic, warm to cool-temperate climate. Rhinoceros habitats include variable forest cover under different climate states. Distinct cool-temperate, partially open vegetation could be recognized for large deer included Cervalces cf carnutorum. A palynostratigraphic correlation between individual spectra and a reference palynostratigraphic record allowed assignment of many fossil remains to a precise stratigraphic position. This procedure also shown that the Leffe local faunas include specimens accumulated under different environmental and climate states, as a consequence of high-frequency climate changes characterizing the Late Villafranchian Early Pleistocene.

  9. The interplay between plasticity and evolution in response to human-induced environmental change

    PubMed Central

    Diamond, Sarah E.; Martin, Ryan A.

    2016-01-01

    Some populations will cope with human-induced environmental change, and others will undergo extirpation; understanding the mechanisms that underlie these responses is key to forecasting responses to environmental change. In cases where organisms cannot disperse to track suitable habitats, plastic and evolved responses to environmental change will determine whether populations persist or perish. However, the majority of studies consider plasticity and evolution in isolation when in fact plasticity can shape evolution and plasticity itself can evolve. In particular, whether cryptic genetic variation exposed by environmental novelty can facilitate adaptive evolution has been a source of controversy and debate in the literature and has received even less attention in the context of human-induced environmental change. However, given that many studies indicate organisms will be unable to keep pace with environmental change, we need to understand how often and the degree to which plasticity can facilitate adaptive evolutionary change under novel environmental conditions. PMID:28003883

  10. Dancing to the rhythms of the Pleistocene? Early Middle Paleolithic population dynamics in NW Iberia (Duero Basin and Cantabrian Region)

    NASA Astrophysics Data System (ADS)

    Sánchez Yustos, Policarpo; Diez Martín, Fernando

    2015-08-01

    The Northwest of Iberia has yielded one of the most complete European Middle Paleolithic records. Despite this wealth of information, very little is known about population dynamics during this period. For that reason, the main concern of this paper is to provide socio-environmental models that may help explain Early Middle Paleolithic (EMP) population dynamics in NW Iberia, assessing to what extent they were shaped by climate forces. The archaeological record is analyzed on the basis of the heuristics of ecological models, already employed in the European Pleistocene record but never at a regional scale, in order to detect long-term changes in the composition of EMP populations, and the environmental, biological and sociocultural process influencing those changes. According to the models proposed, we have detected a long-term population dynamic between MIS 11 and MIS 6, characterized by low environmental stress, high biological productivity, interaction among populations and sociocultural complexity. Eventually, this population dynamic was broken due to an extreme climate phase in late MIS 6 that had a profound impact on populations and sociocultural structures. As a result, the Upper Pleistocene population of NW Iberia was concentrated in the Cantabrian region. This area became an isolated Neanderthal glacial refugium that hosted a population with different origins and fragile long-term demographic stability.

  11. The magnitude and rapidity of the climate change marking the end of the Pleistocene in the mid-latitudes of South America

    USGS Publications Warehouse

    Ashworth, A.C.; Hoganson, J.W.

    1993-01-01

    The chi-squared test of independence and cluster analysis of Otsuka similarity coefficients of fossil beetle assemblages from the Chilean Lake Region in the mid-latitudes of South America support the following conclusions: (1) the mean summer temperature of the glacial climate was 4-5??C lower than today's climate; (2) the climatic change from glacial to interglacial mode was in a single step centered on about 14,000 yr B.P.; (3) the climatic change was rapid, and within 1500 years the biota of a moorland had been completely replaced by a biota of a rain forest; (4) by 12,500 yr B.P., the low elevation beetle fauna of the Chilean Lake Region was similar in composition to that of the present day; and (5) no reversal in the postglacial warming trend, equivalent in age to the Younger Dryas Stade, was detected. ?? 1993.

  12. Sedimentological imprints of environmental variability at the Balkan Peninsula on the sediment sequence of Lake Ohrid (Macedonia, Albania) between the Mid Pleistocene Transition and present days: The ICDP SCOPSCO project

    NASA Astrophysics Data System (ADS)

    Francke, Alexander; Wagner, Bernd; Leicher, Niklas; Raphael, Gromig; Leng, Melanie; Lacey, Jack; Vogel, Hendrik; Baumgarten, Henrike; Thomas, Wonik; Zanchetta, Giovanni; Roberto, Sulpizio; Krastel, Sebastian; Lindhorst, Katja

    2015-04-01

    The UNESCO World Heritage site of Lake Ohrid in the Balkans is thought to be the oldest, continuously existing lake in Europe. In order to unravel the geological and evolutionary history of the lake, a deep drilling campaign was conducted in spring 2013 under the umbrella of the ICDP SCOPSCO project. At the coring site "DEEP" in central parts of the lake, more than 1,500 m of sediments were recovered down to a penetration depth of 569 m blf. This sediment sequence is assumed to be more than 1.2 Ma old and likely covers the entire lacustrine deposits of the Lake Ohrid Basin. Currently, an age model for the upper 260m of the DEEP- site sequence is available. This age model is based on chronological tie points (tephrochronology), and wiggle matching of down hole logging data and (bio-)geochemistry data (XRF, TIC, TOC) from the core sequence to the global benthic stack LR04 and local insolation patterns. The data suggests that the upper 260 m of the DEEP-site sequence corresponds to the time period between the Mid Pleistocene Transition (MPT) and present days. During this period, the sedimentological properties of the sediments show a strong dependency on environmental variability in the area. Interglacial deposits appear massive or marbled, contain up to 80 % of CaCO3 (high TIC), high amounts of organic matter (high TOC) and biogenic silica (high BSi), and low contents of clastic material. Glacial deposits are predominantly marbled and calcite is generally absent. Similarly, the amounts of organic matter and biogenic silica are low, and glacial sediments predominately consist of clastic matter. Distinct layers of siderite and uniformly distributed Fe- or Mn- oxides occur in the glacial deposits, vivianite concretions occur in both the glacial and interglacial periods. High CaCO3 contents in deposits formed during warm (interglacial) periods are also known from studies on short pilot cores from Lake Ohrid and are triggered by increased productivity in the lake, such as

  13. Late Pleistocene climatic change in the French Jura (Gigny) recorded in the δ 18O of phosphate from ungulate tooth enamel

    NASA Astrophysics Data System (ADS)

    Fabre, Magali; Lécuyer, Christophe; Brugal, Jean-Philip; Amiot, Romain; Fourel, François; Martineau, François

    2011-05-01

    Oxygen isotope compositions of phosphate in tooth enamel from large mammals (i.e. horse and red deer) were measured to quantify past mean annual air temperatures and seasonal variations between 145 ka and 33 ka in eastern France. The method is based on interdependent relationships between the δ 18O of apatite phosphate, environmental waters and air temperatures. Horse ( Equus caballus germanicus) and red deer ( Cervus elaphus) remains have δ 18O values that range from 14.2‰ to 17.2‰, indicating mean air temperatures between 7°C and 13°C. Oxygen isotope time series obtained from two of the six horse teeth show a sinusoidal-like signal that could have been forced by temperature variations of seasonal origin. Intra-tooth oxygen isotope variations reveal that at 145 ka, winters were colder (- 7 ± 2°C) than at present (3 ± 1°C) while summer temperatures were similar. Winter temperatures mark a well-developed West-East thermal gradient in France of about - 9°C, much stronger than the -4°C difference recorded presently. Negative winter temperatures were likely responsible for the extent and duration of the snow cover, thus limiting the food resources available for large ungulates with repercussions for Neanderthal predators.

  14. Mission to Planet Earth: A program to understand global environmental change

    SciTech Connect

    Not Available

    1994-02-01

    A description of Mission to Planet Earth, a program to understand global environmental change, is presented. Topics discussed include: changes in the environment; global warming; ozone depletion; deforestation; and NASA's role in global change research.

  15. Mission to Planet Earth: A program to understand global environmental change

    NASA Technical Reports Server (NTRS)

    1994-01-01

    A description of Mission to Planet Earth, a program to understand global environmental change, is presented. Topics discussed include: changes in the environment; global warming; ozone depletion; deforestation; and NASA's role in global change research.

  16. Response of Everglades tree islands to environmental change

    USGS Publications Warehouse

    Willard, Debra A.; Bernhardt, Christopher E.; Holmes, Charles W.; Landacre, Bryan; Marot, Marci E.

    2006-01-01

    Tree islands are centers of biodiversity within the Florida Everglades, USA, but the factors controlling their distribution, formation, and development are poorly understood. We use pollen assemblages from tree islands throughout the greater Everglades ecosystem to reconstruct the timing of tree island formation, patterns of development, and response to specific climatic and environmental stressors. These data indicate that fixed (teardrop-shaped) and strand tree islands developed well before substantial human alteration of the system, with initial tree island vegetation in place between 3500 and 500 calibrated years before present (cal yr BP), depending on the location in the Everglades wetland. Tree island development appears to have been triggered by regional- to global-scale climatic events at 2800 cal yr BP, 1600–1500 cal yr BP, 1200–1000 cal yr BP (early Medieval Warm Period), and 500–200 cal yr BP (Little Ice Age). These periods correspond to drought intervals documented in Central and South America and periods of southward displacement of the Intertropical Convergence Zone. The records indicate a coherence of climate patterns in both subtropical North America and the Northern Hemisphere Neotropics. Water management practices of the 20th century altered plant communities and size of tree islands throughout the Everglades. Responses range from loss of tree islands due to artificially long hydroperiods and deep water to expansion of tree islands after flow reductions. These data provide evidence for the rapidity of tree island response to specific hydrologic change and facilitate prediction of the response to future changes associated with Everglades restoration plans.

  17. Winter ecology of spectacled eiders: Environmental characteristics and population change

    USGS Publications Warehouse

    Petersen, M.R.; Douglas, D.C.

    2004-01-01

    We described characteristics of the wintering area used by Spectacled Eiders (Somateria fischeri) in the Bering Sea, Alaska, and evaluated these characteristics in relation to long-term population trends. Remoteness, limited daylight, and extreme weather conditions precluded direct observations, so we derived the location of the wintering area from satellite telemetry, ice conditions from remotely sensed data, weather conditions from archived data sets, and benthic communities from the literature. Based on analyses of two indices spanning 1957-2002 and 1988-2002, we identified no single environmental parameter that explained the precipitous decline in nesting populations in western Alaska. In general, we found that the number of days with extreme sea ice in winter, extreme winds, and winds in spring explained the greatest variability in annual indices. These analyses support the conclusion that annual population estimates on the breeding grounds can be negatively impacted by extended periods of dense sea-ice concentration and weather during the previous winter. Examination of population indices did not support the hypothesis that changes in benthic community on the wintering grounds have contributed to the decline or inhibited the recovery of the Spectacled Eider breeding population in western Alaska.

  18. Changes in Environmental Conditions Modify Infection Kinetics of Dairy Phages.

    PubMed

    Zaburlin, Delfina; Quiberoni, Andrea; Mercanti, Diego

    2017-04-08

    Latent period, burst time, and burst size, kinetic parameters of phage infection characteristic of a given phage/host system, have been measured for a wide variety of lactic acid bacteria. However, most studies to date were conducted in optimal growth conditions of host bacteria and did not consider variations due to changes in external factors. In this work, we determined the effect of temperature, pH, and starvation on kinetic parameters of phages infecting Lactobacillus paracasei, Lactobacillus plantarum, and Leuconostoc mesenteroides. For kinetics assessment, one-step growth curves were carried out in MRS broth at optimal conditions (control), lower temperature, pH 6.0 and 5.0 (MRS6 and MRS5, respectively), or in medium lacking carbon (MRSN) or nitrogen (MRSC) sources. Phage infection was progressively impaired as environmental conditions were modified from optimal. At lower temperature or pH, infection was delayed, as perceived by longer latent and burst times. Burst size, however, was lower, equal or higher than for controls, but this effect was highly dependent on the particular phage-host system studied. Phage infection was strongly inhibited in MRSC, but only mildly impaired in MRSN. Nevertheless, growth of all the bacterial strains tested was severely compromised by starvation, without significant differences between MRSC and MRSN, indicating that nitrogen compounds are specifically required for a successful phage infection, beyond their influence on bacterial growth.

  19. Biogenic and abiogenic sedimentation in the northern East China Sea in response to sea-level change during the Late Pleistocene

    NASA Astrophysics Data System (ADS)

    Kawahata, Hodaka; Nohara, Masato; Aoki, Kaori; Minoshima, Kayo; Gupta, Lallan P.

    2006-08-01

    In order to understand fluctuations in terrestrial and marine environments in response to sea-level change during the last 42 ky, we investigated sedimentation of biogenic and abiogenic components in core MD982195, collected from the northern East China Sea (ECS), one of the largest marginal seas in the world. Amino acids (AAs), major nitrogen compounds in marine organic matter (OM), can be protected inside biogenic material and survive the decomposition process. The total AAs were highly correlated with organic carbon (OC) ( r = 0.91; p < 0.05) but less with total nitrogen (TN) ( r = 0.76; p < 0.05). Therefore, total AAs and OC contents should reflect primary production (PP) more than TN in core MD982195. PP was approximately constant during 42-15 ka, increased in 15-14 ka was kept constant until 7 ka. Then PP increased from 5 ka to the present. IMAGES program is generally interested in high-resolutional reconstruction of paleo-environments in the area with high sedimentation rate, which is mainly due to abundant supply of lithogenic matter. The positive correlation of lithogenic matter with nonarboreal pollens (NAP) abundance suggests that lithogenic matter and NAP were mainly transported from the coastal lowlands created by the large drop in sea level during the glacial period. Large, millennial-scale fluctuations in sea-surface temperature and salinity did not always correspond to sedimentation pulses of OC and lithogenic matter. Sedimentation of biogenic and abiogenic components was more affected by sea-level change, which controls the positions of the coastline and river mouths and the presence of terrestrial environments on the exposed continental shelf. The Japan Sea is also sensitive to sea-level change because of the shallow sills connecting it to other ocean basins.

  20. Late Pleistocene aeolian dust provenances and wind direction changes reconstructed by heavy mineral analysis of the sediments of the Dehner dry maar (Eifel, Germany)

    NASA Astrophysics Data System (ADS)

    Römer, Wolfgang; Lehmkuhl, Frank; Sirocko, Frank

    2016-12-01

    The study presents the results of a heavy mineral analysis from a 38 m long record of lacustrine Eifel maar sediments from a core section of the Dehner dry maar. The record encompasses the period from 29,000 to about 12,500 b2k. Statistical analyses enabled the distinction of local and regional source areas of aeolian material and revealed pronounced changes in the amounts of different heavy mineral species and corresponding changes in the grain size Index (GSI and CSI). The results indicate that during the early stages of MIS2 (39 to 30 m depth) aeolian sediments were supplied mostly from local sources. This period is characterized by low GSI and CSI ratios resulting from a reduced mobility of material due to a vegetation cover. The period between 23,000 and 12,900 b2k is characterized by a higher supply of heavy minerals from regional and more distant sources. Changes in the provenance areas are indicated in inverse relationships between zircon, rutile, tourmaline (ZRT) and carbonate particles. Shifts in the wind direction are documented in pronounced peaks of carbonate particles indicating easterly winds that have crossed the limestone basins in the Eifeler North South Zone. ZRT-group minerals on the other hand suggest a westerly source area from Palaeozoic clastic sedimentary rocks. The heavy mineral assemblage of the LGM section at 23,000 to 15,000 b2k displays a close correspondence with the stratigraphic relationships that have been obtained for the Landscape Evolution Zone 4 of the ELSA-Vegetation Stack of Sirocko et al. (2016). From the Heinrich 2 event onwards the analyses indicate an increasing degree of mixing of heavy minerals from various provinces. This suggests the existence of a presumably incomplete, thin cover of deflated loess-like sediments that has been repeatedly reworked on the elevated surfaces of the Eifel.

  1. Late Pleistocene aeolian dust provenances and wind direction changes reconstructed by heavy mineral analysis of the sediments of the Dehner dry maar (Eifel Mountains, Germany)

    NASA Astrophysics Data System (ADS)

    Lehmkuhl, Frank; Römer, Wolfgang; Sirocko, Frank

    2016-04-01

    The study presents the results of a heavy mineral analysis from a 38 m long record of aeolian sediments from a core section of the Dehner dry maar (Eifel Mountains, Germany). The record encompasses the period from 30 to about 12.5 ka. Heavy-mineral analysis of the silt fraction has been performed at a sampling interval of 1 m. Statistical analyses enabled the distinction of local and regional source areas of aeolian material and revealed pronounced changes in the amounts of different heavy mineral species and corresponding changes in the grain size index (GSI). The results indicate that during the early stages of MIS 2 (40 to 30m depth) aeolian sediments were supplied mostly from local sources. This period is characterized by a low GSI ratio resulting from a reduced mobility of material due to a vegetation cover. The climax of the LGM is characterized by a higher supply of heavy minerals from regional and more distant sources. Changes in the provenance areas are indicated in inverse relationships between zircon, rutile, tourmaline (ZRT) and carbonate particles. Shifts in the wind direction are documented in pronounced peaks of carbonate particles indicating easterly winds that have crossed the limestone basins in the Eifeler North South Zone. ZRT-group minerals on the other hand suggest a westerly source area and a supply from areas consisting of Paleozoic clastic sedimentary rocks. In the periods following the LGM the analyses indicate an increasing degree of mixing of heavy minerals from various provinces. This suggests the existence of a presumably incomplete, thin cover of deflatable loessic sediments that has been repeatedly reworked on the elevated surfaces of the Eifel.

  2. Vegetation and climate changes during the late Pliocene and early Pleistocene in SW Turkey - Response to comments by Elitez et al., Quaternary Research, 84, pp. 448-456

    NASA Astrophysics Data System (ADS)

    Jiménez-Moreno, Gonzalo; Alçiçek, Hülya; Alçiçek, Mehmet Cihat; van den Hoek Ostende, Lars; Wesselingh, Frank P.

    2016-05-01

    We found the comments by Elitez et al. irrelevant to the scientific study on the vegetation history of the Çameli Basin in SW Anatolia, as presented by Jiménez-Moreno et al. (2015). The comments are far from the scientific debate but instead deal with technical issues raised after looking for the studied sites on Google Earth. Elitez et al. argue about the geographic coordinates of the localities and the thickness of the studied successions, appear to have a stationary view of a fossil site as a single spot on the Earth' surface, and forget that a sedimentary layer containing fossils can outcrop laterally with changes in thickness.

  3. The influence of Pleistocene climatic changes and ocean currents on the phylogeography of the southern African barnacle, Tetraclita serrata (Thoracica; Cirripedia).

    PubMed

    Reynolds, Terry V; Matthee, Conrad A; von der Heyden, Sophie

    2014-01-01

    due to differing environmental conditions.

  4. The Influence of Pleistocene Climatic Changes and Ocean Currents on the Phylogeography of the Southern African Barnacle, Tetraclita serrata (Thoracica; Cirripedia)

    PubMed Central

    Reynolds, Terry V.; Matthee, Conrad A.; von der Heyden, Sophie

    2014-01-01

    due to differing environmental conditions. PMID:25054971

  5. One Species, Three Pleistocene Evolutionary Histories: Phylogeography of the Italian Crested Newt, Triturus carnifex

    PubMed Central

    Canestrelli, Daniele; Salvi, Daniele; Maura, Michela; Bologna, Marco A.; Nascetti, Giuseppe

    2012-01-01

    Phylogeographic patterns of temperate species from the Mediterranean peninsulas have been investigated intensively. Nevertheless, as more phylogeographies become available, either unique patterns or new lines of concordance continue to emerge, providing new insights on the evolution of regional biotas. Here, we investigated the phylogeography and evolutionary history of the Italian crested newt, Triturus carnifex, through phylogenetic, molecular dating and population structure analyses of two mitochondrial gene fragments (ND2 and ND4; overall 1273 bp). We found three main mtDNA lineages having parapatric distribution and estimated divergence times between Late Pliocene and Early Pleistocene. One lineage (S) was widespread south of the northern Apennine chain and was further geographically structured into five sublineages, likely of Middle Pleistocene origin. The second lineage (C) was widespread throughout the Padano–Venetian plain and did not show a clear phylogeographic structure. The third lineage (N) was observed in only two populations located on western Croatia/Slovenia. Results of analysis of molecular variance suggested that partitioning populations according to the geographic distribution of these lineages and sublineages explains 76% of the observed genetic variation. The phylogeographic structure observed within T. carnifex and divergence time estimates among its lineages, suggest that responses to Pleistocene environmental changes in this single species have been as diverse as those found previously among several codistributed temperate species combined. Consistent with the landscape heterogeneity, physiographic features, and palaeogeographical evolution of its distribution range, these responses encompass multiple refugia along the Apennine chain, lowland refugia in large peri-coastal plains, and a ‘cryptic’ northern refugium. PMID:22848590

  6. Quaternary environmental changes in the drylands of China - A critical review

    NASA Astrophysics Data System (ADS)

    Yang, Xiaoping; Scuderi, Louis; Paillou, Philippe; Liu, Ziting; Li, Hongwei; Ren, Xiaozong

    2011-11-01

    This paper reviews our current understanding of Quaternary climate and landscape changes in the desert areas of northern China, a key portion of the middle-latitude drylands on Earth. Combining earlier studies with our recent research and experience, we offer a comprehensive picture of the state of Chinese deserts during the Quaternary and, in the interest of enhancing future research, identify knowledge gaps and areas of uncertainty. Lacustrine deposits found over an area ranging from China's western Taklamakan Desert to the eastern Hunshandake Sandy Lands suggest that extensive lakes occurred in China's deserts during the Pleistocene. Analysis of digital elevation models from SRTM (Shuttle Radar Topography Mission) data supports this interpretation and shows the significant extent of these former lakes. New estimates of mean annual evaporation of ca. 1000 mm from lake surfaces and ca. 100 mm from land surfaces, confirms that local and regional rainfall is critical for maintenance of desert lakes in this temperate zone, especially during intervals when the mean annual rainfall is more than 100 mm. Rapid shifts between sand seas and lakes in geologically and environmentally diverse settings suggest that the drylands of China are very sensitive ephemeral systems, and not long-lasting as previously thought. Available chronologies suggest that there were large lakes in the western Taklamakan Desert and the Chadamu Basin during MIS (Marine Isotope Stage) 3, at ˜30 ka, probably related to a period of strong influence of northern hemispheric westerly winds. Channels and elevation models revealed by SRTM data and remains of lacustrine sediments also indicate that there was a large lake in the Hunshandake Sandy Lands in the eastern portion of the desert belt during the Quaternary. There is significant evidence that during the middle Holocene strong summer monsoons led to a relatively large increase in moisture availability in the entire desert belt of northern China

  7. Unconventional politics of unconventional gas: Environmental reframing and policy change

    NASA Astrophysics Data System (ADS)

    Kear, Andrew Robert

    The present Rocky Mountain West natural gas boom, enabled by historic pro-resource-development political, institutional, economic, and cultural structures, is a politically contested battle over values. Volatile political action, unconventional coalitions, and unconventional politics engulf this unconventional gas boom -- especially at the state level. In this comparative case study of natural gas policy in Wyoming, Colorado, and New Mexico, I measure and compare these values, expressed as frames, through textual analysis of interest group public documents and state legislative bills and statutes from 1999-2008. By developing a new measure of state legislative framing, I test the relationship between interest group and institutional framing and also provide a viable measure of policy change useful to Narrative Policy Analysis theory. Results show that competing interest group and state legislative framing efforts are dynamic, measurably different, and periodically correlative. Competing interest groups rarely engage each other, except as the conflict matures when status-quo-supporters break their silence and engage the challengers' frames that have gained legislative traction. Environmental and land-use counter-framing ensues, but status-quo-supporters remain vigilant in their economic framing. Economic frames retain their institutional privilege within Wyoming and New Mexico, but natural gas policy undergoes a complete environmental reframe in the Colorado state legislature. Although the historically dominant economy frame based on "Old West" values remains largely intact, the respective state legislatures partially reframe policy (within 4 years) using environment, alternative land-uses, and democracy frames based on "New West" and long-extant but previously marginalized status-quo-challenger definitions. This reframing is not a strictly partisan issue, but rather it is influenced by political context, policy diffusion, and long-term interest group advocacy and

  8. A 70,000 year multiproxy record of climatic and environmental change from Rano Aroi peatland (Easter Island)

    NASA Astrophysics Data System (ADS)

    Margalef, Olga; Cañellas-Boltà, Núria; Pla-Rabes, Sergi; Giralt, Santiago; Pueyo, Juan Jose; Joosten, Hans; Rull, Valentí; Buchaca, Teresa; Hernández, Armand; Valero-Garcés, Blas L.; Moreno, Ana; Sáez, Alberto

    2013-09-01

    The Rano Aroi mire on Easter Island (also known as Rapa Nui; 27°09‧S, 109°27‧W, 430 m above sea level) provides a unique non-marine record in the central South Pacific Ocean for reconstructing Late Pleistocene environmental changes. The results of a multiproxy study on two cores from the center and margin of the Rano Aroi mire, including peat stratigraphy, facies analysis, elemental and isotope geochemistry on bulk organic matter, X-ray fluorescence (XRF) core scanning and macrofossil analysis, were used to infer past water levels and vegetation changes. The chronology was based on 18 14C AMS dates for the upper 8.7 m. The extrapolated age for the base of the sequence is 70 kyr, which implies that this record is the oldest paleolimnological record on Easter Island. The recovered Rano Aroi sequence consists of a radicel peat formed primarily from the remains of sedges, grasses and Polygonaceae that have accumulated since Marine Isotopic Stage (MIS) 4 (70 kyr BP) to the present. From 60 to 40 kyr BP (MIS 3), high precipitation/runoff events were recorded as organic mud facies with lighter δ13C, low C/N values and high Ti content, indicating higher detritic input to the mire. A gradual shift in δ13C bulk organic matter from - 14% to - 26%, recorded between 50 and 45 cal kyr BP, suggests a progressive change in local peat-forming vegetation from C4 to C3 plant types. Post-depositional Ca and Fe enrichment during sub-aerial peat exposure and very low sedimentation rates indicate lower water tables during Late MIS 3 (39-31 cal kyr BP). During MIS 2 (27.8-19 cal kyr BP), peat production rates were very low, most likely due to cold temperatures, as reconstructed from other Easter Island records during the Last Glacial Maximum (LGM). Geochemical and macrofossil evidence shows that peat accumulation reactivates at approximately 17.5 cal kyr BP, reaching the highest accumulation rates at 14 cal kyr BP. Peat accretion decreased from 5.0 to 2.5 cal kyr BP, coinciding

  9. Quaternary climate and environmental changes have shaped genetic differentiation in a Chinese pheasant endemic to the eastern margin of the Qinghai-Tibetan Plateau.

    PubMed

    Gu, Langyu; Liu, Yang; Que, Pinjia; Zhang, Zhengwang

    2013-04-01

    The geological complexity generated by the uplift of the Qinghai-Tibetan Plateau and the resulting habitat heterogeneity have functioned together with climatic oscillations in the Quaternary to have a profound impact on the patterns of genetic diversity and demography of the fauna in this region. To understand the effect of the climatic and environmental shifts of the Quaternary on intraspecific genetic patterns and evolutionary history, we investigated the population genetic structure of the blue eared pheasant (Crossoptilon auritum), an endemic bird inhabiting the easternmost region of the plateau. Our phylogeographic analysis of mitochondrial DNA sequences and eight autosomal microsatellites reveals that the blue eared pheasant is subdivided into four distinct subpopulations: a central group (Huzhu and Taizi Mountains), a southern Zoige group, a southernmost Wanglang group and the northernmost Helan Mountain group. These groups are likely to have diverged in the Pleistocene, corresponding to geological changes and the interglacial-glacial climate oscillations that occurred at the eastern margin of the Qinghai-Tibetan Plateau. These subpopulations thus represent major conservation units, especially for the isolated Helan subpopulation. Our findings provide evidence of population divergence driven by complex Quaternary climate and environmental changes and, once more, highlight the importance of phylogeographic studies for conservation endeavours.

  10. Pleistocene and pre-Pleistocene Begonia speciation in Africa.

    PubMed

    Plana, Vanessa; Gascoigne, Angus; Forrest, Laura L; Harris, David; Pennington, R Toby

    2004-05-01

    This paper presents a historical biogeographic analysis of African Begonia based on combined internal transcribed spacer (ITS) and trnL intron sequences. Age range estimates for Begonia in Africa ranged from only 1.5 Ma for some terminal nodes to 27 Ma for basal nodes when the ages of Réunion (2 Ma) andMayotte (5.4 Ma) were used to date the split between Begonia salaziensis and Begonia comorensis. Assuming a more recent origin age for Begonia salaziensis (2 Ma) provided age estimates in other parts of the phylogeny which agreed with patterns observed in other African organisms. A large proportion of the Begonia diversity seen today in Africa is of pre-Pleistocene origin. Species of Pleistocene origin are concentrated in species-rich groups such as sections Loasibegonia, Scutobegonia, and Tetraphila, which have their centre of diversity in western Central Africa. Phylogenetically isolated taxa such as Begonia longipetiolata, Begonia iucunda, and Begonia thomeana date to the late Miocene, a period of extended aridification on the African continent that had severe effects on African rain forest species. A general pattern is identified where phylogenetically isolated species occur outside the main identified rain forest refuges. Endemic species on the island of São Tomé such as Begonia baccata, Begonia molleri, and Begonia subalpestris appear to be palaeoendemics. Of these species, the most recent age estimate is for B. baccata, which is dated at ca. 3 Ma. Therefore, São Tomé appears to have functioned as an important (if previously unrecognised) pre-Pleistocene refuge. On the mainland, areas such as the Massif of Chaillu in Gabon, southern Congo (Brazzaville), and far western areas of Congo (Kinshasa) have played similar roles to São Tomé.

  11. Environmental changes in the neogene and the biotic response

    NASA Astrophysics Data System (ADS)

    Barash, M. S.

    2011-04-01

    Among the abiotic factors that determined via the paleoceanographic processes development and evolution of the oceanic biota in the Neogene, noteworthy are the tectonic, volcanic, climatic and extraterrestrial events. The most important tectonic events of such kind include the subsidence of the Faroe-Iceland Threshold 14-13 Ma ago, the closure of the Tethys Ocean in the east 19-12 Ma ago, the orogenesis in the western Mediterranean region and closure of the Mediterranean Sea (Messinian Crisis) 5.59-5.33 Ma ago, the formation of the Central American Isthmus 6.0-3.5 Ma ago, and the opening of the Bering Strait that occurred (according to different data) in the period of 7.4 to 3.1 Ma ago. The most significant climatic consequence resulted from the formation of the Circum-Antarctic Current, the irregular growth of the Antarctic ice shield, the cooling in the Arctic region 3.2-3.1 Ma ago, and the development of continental glaciations in the Northern Hemisphere approximately 2.5 Ma ago. The variations in the atmospheric CO2 content are correlative with the climatic fluctuations. The entire Cenozoic climatic record reflects the influence of the orbital parameters of the Earth. The Neogene was marked by several significant extraterrestrial events: the fireball falling in southwestern Germany in the middle Miocene 14.8-14.5 Ma ago probably accompanied by enhanced volcanic activity particularly in the rift valley of eastern Africa; the drastically increased influx of interplanetary dust due to the disruption caused by a large asteroid in the late Miocene 8.3 ± 0.5 Ma ago, the fall of a large (>1 km in diameter) asteroid in the Eltanin Fault zone of the Southern Ocean in the terminal Pliocene 2.15 Ma ago; and the explosion of a supernova star, which was probably responsible for the partial extinction of marine organisms at the Pliocene-Pleistocene transition approximately 2 Ma ago.

  12. Introduction to Pliocene-Pleistocene paleoceanography of the Bering Sea

    NASA Astrophysics Data System (ADS)

    Takahashi, Kozo; Ravelo, A. Christina; Okazaki, Yusuke

    2016-03-01

    High resolution paleoceanography of the Pliocene-Pleistocene is important in understanding climate forcing mechanisms and associated environmental changes during this major transition from global warmth to the Ice Ages. This is particularly true in high latitude marginal seas such as the Bering Sea. The Bering Sea has been very sensitive to changes in global climate during interglacial and glacial, or Milankovitch, time scales. This is due to significant changes in water circulation, land-ocean interaction, and sea-ice formation. With the aim to reveal the climate and oceanographic history of the Bering Sea over the past 5 My, IODP Expedition 323 cored a total of 5741 m of sediment (97.4% recovery) at seven sites in 2009 on D/V JOIDES Resolution covering three regions: the Umnak Plateau, the Bowers Ridge, and the Bering Slope. The water depths of the drill sites range from 818 m to 3174 m, allowing for the characterization of past vertical water mass distribution including changes in the oxygen minimum zone. The four deepest holes range from 600 m to 745 m below the seafloor, and resulted in the recovery of long sediment sequences ranging from 1.9 My to 5 My in age. Following the expedition, two sampling parties at Kochi Core Center (for acquisition of ca. 58,000 subsamples) and two scientific meetings were conducted in order to proceed with the analyses of sediment core samples and discussions. Here, pertinent results, primarily from IODP Expedition 323, are consolidated as a single special volume of Deep-Sea Research Part II Topical Studies in Oceanography.

  13. Late Pleistocene adult mortality patterns and modern human establishment

    PubMed Central

    Trinkaus, Erik

    2011-01-01

    The establishment of modern humans in the Late Pleistocene, subsequent to their emergence in eastern Africa, is likely to have involved substantial population increases, during their initial dispersal across southern Asia and their subsequent expansions throughout Africa and into more northern Eurasia. An assessment of younger (20–40 y) versus older (>40 y) adult mortality distributions for late archaic humans (principally Neandertals) and two samples of early modern humans (Middle Paleolithic and earlier Upper Paleolithic) provides little difference across the samples. All three Late Pleistocene samples have a dearth of older individuals compared with Holocene ethnographic/historical samples. They also lack older adults compared with Holocene paleodemographic profiles that have been critiqued for having too few older individuals for subsistence, social, and demographic viability. Although biased, probably through a combination of preservation, age assessment, and especially Pleistocene mobility requirements, these adult mortality distributions suggest low life expectancy and demographic instability across these Late Pleistocene human groups. They indicate only subtle and paleontologically invisible changes in human paleodemographics with the establishment of modern humans; they provide no support for a life history advantage among early modern humans. PMID:21220336

  14. Potential Perils of Changing Environmental Context on Examination Scores

    ERIC Educational Resources Information Center

    Van Der Wege, Mija; Barry, Leslie A.

    2008-01-01

    Environmental context can affect memory retrieval in a wide range of situations. The authors investigate the relationship between the location of a collegiate final examination and student performance. Although several other studies have looked at the impact of environmental context on test taking, this study does so in a real-world environment,…

  15. Changing Issue Representation among Major United States Environmental Movement Organizations

    ERIC Educational Resources Information Center

    Johnson, Erik

    2006-01-01

    Histories of the environmental movement have emphasized the importance of a shift in focus from those issues traditionally associated with the movement, such as resource and wildlife protection, towards "new" quality of life issues, such as environmental pollution and its human health effects. Here, time-series data between 1970 and 2000…

  16. Rethinking Environmental Protection: Meeting the Challenges of a Changing World

    EPA Science Inventory

    Background: The U.S. Environmental Protection Agency (EPA) has made great progress in addressing some major environmental problems. These successes were framed within EPA’s statutory mandates which are largely media-specific and receptor-focused and follow a segmented risk-...

  17. Late Pliocene/Pleistocene changes in Arctic sea-ice cover: Biomarker and dinoflagellate records from Fram Strait/Yermak Plateau (ODP Sites 911 and 912)

    NASA Astrophysics Data System (ADS)

    Stein, Ruediger; Fahl, Kirsten; Matthiessen, Jens

    2014-05-01

    Sea ice is a critical component in the (global) climate system that contributes to changes in the Earth's albedo (heat reduction) and biological processes (primary productivity), as well as deep-water formation, a driving mechanism for global thermohaline circulation. Thus, understanding the processes controlling Arctic sea ice variability is of overall interest and significance. Recently, a novel and promising biomarker proxy for reconstruction of Arctic sea-ice conditions was developed and is based on the determination of a highly-branched isoprenoid with 25 carbons (IP25; Belt et al., 2007; PIP25 when combined with open-water phytoplankton biomarkers; Müller et al., 2011). Here, we present biomarker data from Ocean Drilling Program (ODP) Sites 911 and 912, recovered from the southern Yermak Plateau and representing information of sea-ice variability, changes in primary productivity and terrigenous input during the last about 3.5 Ma. As Sites 911 and 912 are close to the modern sea-ice edge, their sedimentary records seem to be optimal for studying past variability in sea-ice coverage and testing the applicability of IP25 and PIP25 in older sedimentary sequences. In general, our biomarker records correlate quite well with other climate and sea-ice proxies (e.g., dinoflagellates, IRD, etc.). The main results can be summarized as follows: (1) The novel IP25/PIP25 biomarker approach has potential for semi-quantitative paleo-sea ice studies covering at least the last 3.5 Ma, i.e., the time interval including the onset (intensification) of major Northern Hemisphere Glaciation (NHG). (2) These data indicate that sea ice of variable extent was present in the Fram Strait/southern Yermak Plateau area during most of the time period under investigation. (3) Elevated IP25/PIP25 values indicative for an extended spring sea-ice cover, already occurred between 3.6 and 2.9 Ma, i.e., prior to the onset of major NHG. This may suggest that sea-ice and related albedo effects might

  18. Comparison between the Amount of Environmental Change and the Amount of Transcriptome Change

    PubMed Central

    Ogata, Norichika; Kozaki, Toshinori; Yokoyama, Takeshi; Hata, Tamako; Iwabuchi, Kikuo

    2015-01-01

    Cells must coordinate adjustments in genome expression to accommodate changes in their environment. We hypothesized that the amount of transcriptome change is proportional to the amount of environmental change. To capture the effects of environmental changes on the transcriptome, we compared transcriptome diversities (defined as the Shannon entropy of frequency distribution) of silkworm fat-body tissues cultured with several concentrations of phenobarbital. Although there was no proportional relationship, we did identify a drug concentration “tipping point” between 0.25 and 1.0 mM. Cells cultured in media containing lower drug concentrations than the tipping point showed uniformly high transcriptome diversities, while those cultured at higher drug concentrations than the tipping point showed uniformly low transcriptome diversities. The plasticity of transcriptome diversity was corroborated by cultivations of fat bodies in MGM-450 insect medium without phenobarbital and in 0.25 mM phenobarbital-supplemented MGM-450 insect medium after previous cultivation (cultivation for 80 hours in MGM-450 insect medium without phenobarbital, followed by cultivation for 10 hours in 1.0 mM phenobarbital-supplemented MGM-450 insect medium). Interestingly, the transcriptome diversities of cells cultured in media containing 0.25 mM phenobarbital after previous cultivation (cultivation for 80 hours in MGM-450 insect medium without phenobarbital, followed by cultivation for 10 hours in 1.0 mM phenobarbital-supplemented MGM-450 insect medium) were different from cells cultured in media containing 0.25 mM phenobarbital after previous cultivation (cultivation for 80 hours in MGM-450 insect medium without phenobarbital). This hysteretic phenomenon of transcriptome diversities indicates multi-stability of the genome expression system. Cellular memories were recorded in genome expression networks as in DNA/histone modifications. PMID:26657512

  19. Environmental Changes Can Produce Shifts in Chagas Disease Infection Risk

    PubMed Central

    Cordovez, Juan M; Sanabria, Camilo

    2014-01-01

    An epidemiological network contains all the organisms involved (types) in the transmission of a parasite. The nodes of the network represent reservoirs, hosts, and vectors, while the links between the nodes represent the strength and direction of parasite movement. Networks that contain humans are of special interest because they are of concern to public health authorities. Under these circumstances, it is possible, in principle, to identify cycles (closed paths in the network) that include humans and select the ones that carry the maximum probability of human infection. The basic reproduction number R0 in such a network gives the average number of new infections of any type after the introduction of one individual infected by any type. To obtain R0 for complex networks, one can use the next-generation matrix (NGM) approach. Every entry in NGM will average the contribution of each link that connects two types. To tease the contribution of every cycle apart, we define the virulence as the geometric mean of the NGM entries corresponding to the links therein. This approach allows for the quantification of specific cycles of interest while it also makes the computation of the sensitivity and elasticity of the parameters easier. In this work, we compute the virulence for the transmission dynamics of Chagas disease for a typical rural area in Colombia incorporating the effect of environmental changes on the vector population size. We concluded that the highest contribution to human infection comes from humans themselves, which is a surprising and interesting result. In addition, sensitivity analysis revealed that increasing vector population size increases the risk of human infection. PMID:25574142

  20. Environmental changes can produce shifts in chagas disease infection risk.

    PubMed

    Cordovez, Juan M; Sanabria, Camilo

    2014-01-01

    An epidemiological network contains all the organisms involved (types) in the transmission of a parasite. The nodes of the network represent reservoirs, hosts, and vectors, while the links between the nodes represent the strength and direction of parasite movement. Networks that contain humans are of special interest because they are of concern to public health authorities. Under these circumstances, it is possible, in principle, to identify cycles (closed paths in the network) that include humans and select the ones that carry the maximum probability of human infection. The basic reproduction number R 0 in such a network gives the average number of new infections of any type after the introduction of one individual infected by any type. To obtain R 0 for complex networks, one can use the next-generation matrix (NGM) approach. Every entry in NGM will average the contribution of each link that connects two types. To tease the contribution of every cycle apart, we define the virulence as the geometric mean of the NGM entries corresponding to the links therein. This approach allows for the quantification of specific cycles of interest while it also makes the computation of the sensitivity and elasticity of the parameters easier. In this work, we compute the virulence for the transmission dynamics of Chagas disease for a typical rural area in Colombia incorporating the effect of environmental changes on the vector population size. We concluded that the highest contribution to human infection comes from humans themselves, which is a surprising and interesting result. In addition, sensitivity analysis revealed that increasing vector population size increases the risk of human infection.

  1. Paleosols as Archives of Environmental Change in Deep Time

    NASA Astrophysics Data System (ADS)

    Crowley, Quentin

    2015-04-01

    Paleosols develop at the geosphere-atmosphere interface and potentially provide an archive of environmental conditions at the time of their formation. Although paleosols from deep time can be difficult to recognize due to the masking of pedogenic features by metamorphism and deformation, they may record transient (i.e. time-dependent) events which are often difficult to recognize in other geological proxies. Paleosols from the Archean and Paleoproterozoic are rare and complex to study, but offer an opportunity to gain insight into what may be relatively short-scale temporal variations in the Earth's atmospheric composition. For instance, it is widely believed that atmospheric oxygen saturation rose from <10E-05 present atmospheric level (PAL) in the Archean to >10E-02 PAL at the Great Oxidation Event (GOE) at ca. 2.4 Ga. Until recently however, chemical or physical evidence from paleosols for earlier oxygenation events were generally thought to be lacking. Recent studies of paleosols from eastern India (Keonjhar Paleosol, Singhbhum Craton) and South Africa (Nsuze Paleosol, Kaapvaal Craton) have provided chemical evidence for transient Mesoarchean atmospheric oxygenation at ca. 3.0 Ga. These paleosols are considered to preserve the earliest known vestiges of terrestrial oxidative weathering, signifying a transient, early oxygen accumulation in the Earth's atmosphere. This has far-reaching implications from both atmospheric and biological evolutionary perspectives in that chemical signatures preserved in these Mesoarchean paleosols are thought to signify the presence of molecular oxygen at levels higher than those attributable to photo-dissociation of atmospheric water alone. Such elevated levels of atmospheric oxygen could only be due to the presence of a sufficiently large biomass of micro-organisms capable of oxidative photosynthesis. Although the Archean-Paleoproterozoic paleosol geological record is fragmentary and geochemical signatures are not necessarily

  2. Evolutionary History of Lagomorphs in Response to Global Environmental Change

    PubMed Central

    Ge, Deyan; Wen, Zhixin; Xia, Lin; Zhang, Zhaoqun; Erbajeva, Margarita; Huang, Chengming; Yang, Qisen

    2013-01-01

    Although species within Lagomorpha are derived from a common ancestor, the distribution range and body size of its two extant groups, ochotonids and leporids, are quite differentiated. It is unclear what has driven their disparate evolutionary history. In this study, we compile and update all fossil records of Lagomorpha for the first time, to trace the evolutionary processes and infer their evolutionary history using mitochondrial genes, body length and distribution of extant species. We also compare the forage selection of extant species, which offers an insight into their future prospects. The earliest lagomorphs originated in Asia and later diversified in different continents. Within ochotonids, more than 20 genera occupied the period from the early Miocene to middle Miocene, whereas most of them became extinct during the transition from the Miocene to Pliocene. The peak diversity of the leporids occurred during the Miocene to Pliocene transition, while their diversity dramatically decreased in the late Quaternary. Mantel tests identified a positive correlation between body length and phylogenetic distance of lagomorphs. The body length of extant ochotonids shows a normal distribution, while the body length of extant leporids displays a non-normal pattern. We also find that the forage selection of extant pikas features a strong preference for C3 plants, while for the diet of leporids, more than 16% of plant species are identified as C4 (31% species are from Poaceae). The ability of several leporid species to consume C4 plants is likely to result in their size increase and range expansion, most notably in Lepus. Expansion of C4 plants in the late Miocene, the so-called ‘nature’s green revolution’, induced by global environmental change, is suggested to be one of the major ‘ecological opportunities’, which probably drove large-scale extinction and range contraction of ochotonids, but inversely promoted diversification and range expansion of leporids

  3. Mastodon herbivory in mid-latitude late-Pleistocene boreal forests of eastern North America

    NASA Astrophysics Data System (ADS)

    Teale, Chelsea L.; Miller, Norton G.

    2012-07-01

    Skeletal remains of the extinct American mastodon have often been found with deposits of short, decorticated twigs intermixed with plant fragments presumed to be gastrointestinal or fecal material. If such deposits are digesta, paleobotanical evidence may be used to analyze mastodon foraging strategy, with implications for assessing habitat selection, ecological roles, and response to environmental change. To identify components of mastodon diet in mid-latitude late-Pleistocene boreall forests of eastern North America, plant macrofossils and pollen from a molar socket (Hyde Park site, New York) were compared with dispersed deposits associated with skeletal remains (Hiscock and Chemung sites, New York). Similar macrofossil condition and twig morphology among samples, but difference from a modern boreal fen analog, confirmed the deposits were digesta. Comparison of twigs with material from other paleontological sites and modern elephants suggested dimensions generally indicative of digesta. Picea formed the bulk of each sample but Pinus may have been locally important. Wintertime browsing of Salix and Populus, and springtime consumption of Alnus, were indicated. Evidence for Cyperaceae, Gramineae, and Compositae was ambiguous. If conifers, broadleaf trees, shrubs, and herbs were necessary to fulfill dietary requirements, mastodons would have been nutritionally stressed by rapid late-Pleistocene decrease in vegetational diversity.

  4. The Glacier Peak Tephra: A Continental-Scale Latest Pleistocene Time Horizon

    NASA Astrophysics Data System (ADS)

    Pyne-O'Donnell, S.; Cwynar, L. C.; Vincent, J. H.; Spear, R.; Froese, D. G.

    2014-12-01

    The latest Pleistocene eruptions of Glacier Peak in the Cascade Range deposited a widespread set of tephras throughout much of western North America within a short time span where they serve as valuable marker layers for inter-site correlation and chronostratigraphical control. We report the detection of these tephras in microscopic form in three lakes along the Eastern Seaboard (Maine and Nova Scotia). These distinct distal lake layers occur as closely spaced couplets which retain the subtle geochemical variation that characterises the proximal Glacier Peak G and B layers. New radiocarbon dates for the tephras also closely corroborate the most recently revised proximal dates for the tephras (ca. 13,700 - 13,400 cal. yr B.P) which found that they are ca. 400 14C yr older than hitherto thought. Their presence this far eastward implies that their deposition spans the intervening continent (>4000 km) and adds to a developing distal tephrostratigraphical framework with applications to studies of latest Pleistocene deglaciation and environmental change, megafaunal extinction and archaeology.

  5. Using (1)(0)Be cosmogenic isotopes to estimate erosion rates and landscape changes during the Plio-Pleistocene in the Cradle of Humankind, South Africa.

    PubMed

    Dirks, Paul H G M; Placzek, Christa J; Fink, David; Dosseto, Anthony; Roberts, Eric

    2016-07-01

    Concentrations of cosmogenic (10)Be, measured in quartz from chert and river sediment around the Cradle of Humankind (CoH), are used to determine basin-averaged erosion rates and estimate incision rates for local river valleys. This study focusses on the catchment area that hosts Malapa cave with Australopithecus sediba, in order to compare regional versus localized erosion rates, and better constrain the timing of cave formation and fossil entrapment. Basin-averaged erosion rates for six sub-catchments draining the CoH show a narrow range (3.00 ± 0.28 to 4.15 ± 0.37 m/Mega-annum [Ma]; ±1σ) regardless of catchment size or underlying geology; e.g. the sub-catchment with Malapa Cave (3 km(2)) underlain by dolomite erodes at the same rate (3.30 ± 0.30 m/Ma) as the upper Skeerpoort River catchment (87 km(2)) underlain by shale, chert and conglomerate (3.23 ± 0.30 m/Ma). Likewise, the Skeerpoort River catchment (147 km(2)) draining the northern CoH erodes at a rate (3.00 ± 0.28 m/Ma) similar to the Bloubank-Crocodile River catchment (627 km(2)) that drains the southern CoH (at 3.62 ± 0.33 to 4.15 ± 0.37 m/Ma). Dolomite- and siliciclastic-dominated catchments erode at similar rates, consistent with physical weathering as the rate controlling process, and a relatively dry climate in more recent times. Erosion resistant chert dykes along the Grootvleispruit River below Malapa yield an incision rate of ∼8 m/Ma at steady-state erosion rates for chert of 0.86 ± 0.54 m/Ma. Results provide better palaeo-depth estimates for Malapa Cave of 7-16 m at the time of deposition of A. sediba. Low basin-averaged erosion rates and concave river profiles indicate that the landscape across the CoH is old, and eroding slowly; i.e. the physical character of the landscape changed little in the last 3-4 Ma, and dolomite was exposed on surface probably well into the Miocene. The apparent absence of early Pliocene- or Miocene-aged cave deposits and

  6. Systematics of past changes in ocean ventilation: a comparison of Cretaceous Ocean Anoxic Event 2 and Pleistocene to Holocene Oxygen Minimum Zones

    NASA Astrophysics Data System (ADS)

    Schönfeld, J.; Kuhnt, W.; Erdem, Z.; Flögel, S.; Glock, N.; Aquit, M.; Frank, M.; Holbourn, A.

    2014-09-01

    Present day oceans are generally well ventilated except mid-depth oxygen minimum zones (OMZs) under high surface water productivity regimes, regions of sluggish circulation, and restricted marginal basins. In the Mesozoic, however, entire oceanic basins transiently became dysoxic or even anoxic. In particular the Cretaceous Ocean Anoxic Events (OAEs) were characterised by laminated organic-carbon rich shales and low-oxygen indicating trace fossil assemblages preserved in the sedimentary record. Yet both, qualitative and quantitative assessments of intensity and extent of Cretaceous near-bottom water oxygenation have been hampered by deep or long-term diagenesis and the evolution of marine biota serving as oxygen indicators in today's ocean. Sedimentary features similar to those found in Cretaceous strata were observed in deposits underlying Recent OMZs, where bottom-water oxygen levels, the flux of organic matter, and benthic life are well known. Their implications for constraining past bottom-water oxygenation are addressed in this review, with emphasis on comparing OMZ sediments from the Peruvian upwelling with deposits of the late Cenomanian OAE 2 from the Atlantic NW African shelf. Holocene laminated sediments were encountered at bottom-water oxygen levels of <7 μmol kg-1 under the Peruvian upwelling and <5 μmol kg-1 in California Borderland basins and the Pakistan Margin. Changes of sediment input on seasonal to decadal time scales are necessary to create laminae of different composition. However, bottom currents may shape similar textures that are difficult to discern from primary seasonal laminae in sediment cores. The millimetre-sized trace fossil Chondrites was commonly found in Cretaceous strata and Recent oxygen-depleted environments where its diameter increased with oxygen levels from 5 to 45 μmol kg-1. This ichnogenus has not been reported from Peruvian sediments but cm-sized crab burrows appeared around 10 μmol kg-1, which may indicate a minimum

  7. The Sima de los Huesos (Burgos, northern Spain): palaeoenvironment and habitats of Homo heidelbergensis during the Middle Pleistocene

    NASA Astrophysics Data System (ADS)

    García, Nuria; Arsuaga, Juan Luis

    2011-06-01

    Interpreting how environmental dynamics respond to global climate change and how this has affected human evolution and dispersal is an on-going topic of debate. During the early Middle Pleistocene (˜0.6-0.4 Ma), as compared to earlier, environmental conditions were relatively more stable, with longer climatic cycles alternating between open and forested landscapes. During this interval, humans spread successfully providing an important number of fossil sites where fossils or tools are reported. The Atapuerca-Sima de los Huesos (Burgos, northern Spain) site (Atapuerca-SH) is one of the earliest localities with hominin evidence in the European Middle Pleistocene, with the most important accumulation of Homo heidelbergensis so far. We have analyzed the abundant faunal record from Sima de los Huesos, which is mainly comprised of carnivores, in order to approach an interpretation of the palaeoenvironmental circumstances where these hominids inhabited within the Sierra. Other sites from Sierra de Atapuerca referred to the same Faunal Unit (FU 6), are roughly contemporaneous, and include important ungulates, which are here analyzed with Atapuerca-SH. Additional information provided by isotopic analysis helps elucidate the ancient ecology of taxa present in Sima de los Huesos allowing for an accurate portrayal of the setting in which humans lived. The timing of the spread of Homo heidelbergensis is dominated by a relative climatic and environmental stability and points to a landscape dominated by savannah-like open woodland.

  8. Climate patriots? Concern over climate change and other environmental issues in Australia.

    PubMed

    Tranter, Bruce; Lester, Libby

    2015-12-15

    Echoing the anti-pollution and resource conservation campaigns in the United States in the early-to-mid-twentieth century, some scholars advocate mobilising support for environmental issues by harnessing the notion of environmental patriotism. Taking action to reduce the impact of global warming has also been cast as a patriotic cause. Drawing upon quantitative data from a recent national survey, we examine the link between patriotism and environmental attitudes in Australia, focussing upon climate change. We find that patriotism has a largely neutral association with concern over environmental issues, with the exception of climate change and, to a lesser extent, wildlife preservation. Expressing concern over climate change appears to be unpatriotic for some Australians. Even after controlling for political party identification and other important correlates of environmental issue concerns, patriots are less likely than others to prioritise climate change as their most urgent environmental issue and less likely to believe that climate change is actually occurring.

  9. Late Pleistocene and Holocene groundwater recharge from the chloride mass balance method and chlorine-36 data

    NASA Astrophysics Data System (ADS)

    Zhu, Chen; Winterle, James R.; Love, Erica I.

    2003-07-01

    The chloride mass balance (CMB) method for estimating groundwater recharge is economic and effective, provided that the hydrological conditions for its applications are met and the modeling parameters are known. However, modeling parameters such as precipitation and Cl- deposition rates vary temporally, most notably as a result of the climatic changes from late Pleistocene to Holocene. The temporal variability of atmospheric Cl- input and annual precipitation were considered in this study by using a discrete steady state CMB model with different parameters for late Pleistocene and Holocene. Cl- deposition rates, estimated from 36Cl data, were lower in late Pleistocene than Holocene at Yucca Mountain, Nevada, but higher in late Pleistocene than Holocene at Black Mesa, Arizona. Paleoclimate proxies at both Yucca Mountain and Black Mesa point to higher precipitation rates in late Pleistocene than Holocene. The resulting average recharge estimates for Black Mesa are 9 ± 5 mm/yr for Holocene and 35 ± 22 mm/yr for late Pleistocene. Local recharge rates at Yucca Mountain were estimated from the 36Cl/Cl ratios and Cl- concentrations in perched waters. The estimated recharge for Yucca Mountain is 5 ± 1 mm/yr for Holocene and 15 ± 5 mm/yr for late Pleistocene. These recharge rates are comparable to results of independent numerical groundwater flow models and watershed-scale infiltration models at Black Mesa and Yucca Mountain, respectively.

  10. Late-Pleistocene precipitation δ18O interpolated across the global landmass