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Sample records for pleistocene environmental change

  1. Pleistocene reefs of the Egyptian Red Sea: environmental change and community persistence

    PubMed Central

    2017-01-01

    The fossil record of Red Sea fringing reefs provides an opportunity to study the history of coral-reef survival and recovery in the context of extreme environmental change. The Middle Pleistocene, the Late Pleistocene, and modern reefs represent three periods of reef growth separated by glacial low stands during which conditions became difficult for symbiotic reef fauna. Coral diversity and paleoenvironments of eight Middle and Late Pleistocene fossil terraces are described and characterized here. Pleistocene reef zones closely resemble reef zones of the modern Red Sea. All but one species identified from Middle and Late Pleistocene outcrops are also found on modern Red Sea reefs despite the possible extinction of most coral over two-thirds of the Red Sea basin during glacial low stands. Refugia in the Gulf of Aqaba and southern Red Sea may have allowed for the persistence of coral communities across glaciation events. Stability of coral communities across these extreme climate events indicates that even small populations of survivors can repopulate large areas given appropriate water conditions and time. PMID:28674659

  2. Pleistocene reefs of the Egyptian Red Sea: environmental change and community persistence.

    PubMed

    Casazza, Lorraine R

    2017-01-01

    The fossil record of Red Sea fringing reefs provides an opportunity to study the history of coral-reef survival and recovery in the context of extreme environmental change. The Middle Pleistocene, the Late Pleistocene, and modern reefs represent three periods of reef growth separated by glacial low stands during which conditions became difficult for symbiotic reef fauna. Coral diversity and paleoenvironments of eight Middle and Late Pleistocene fossil terraces are described and characterized here. Pleistocene reef zones closely resemble reef zones of the modern Red Sea. All but one species identified from Middle and Late Pleistocene outcrops are also found on modern Red Sea reefs despite the possible extinction of most coral over two-thirds of the Red Sea basin during glacial low stands. Refugia in the Gulf of Aqaba and southern Red Sea may have allowed for the persistence of coral communities across glaciation events. Stability of coral communities across these extreme climate events indicates that even small populations of survivors can repopulate large areas given appropriate water conditions and time.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  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. 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)

  16. 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.

  17. 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

  18. Climate, environmental change and taphonomic processes in the Pliocene and Early Pleistocene of the South-West Caspian Sea

    NASA Astrophysics Data System (ADS)

    Hoyle, T. M. V.; Leroy, S.; Lopez-Merino, L.

    2016-12-01

    The Caspian Sea is the largest endorheic lake in the world and is highly sensitive to climate change. During the Pliocene, a thick series of sediments was deposited in the South Caspian Basin that now contains important oil and gas reserves. A reliable, well-dated climate and palaeoenvironment proxy record was created for the Pliocene and Early Pleistocene of the South Caspian Basin in Azerbaijan. We assessed climate cyclicity at the Milankovitch level to test whether a link could be demonstrated between climate and sedimentation patterns in Azerbaijan's primary hydrocarbon producing formations (Productive Series) as well as in the top seal (Akchagyl Formation). Magnetostratigraphy and radiometric dating (40Ar/39Ar on volcanic ashes) of the quasi-marine Akchagyl Formation assigned this section to the Late Pliocene-Early Pleistocene. Palaeoenvironments were reconstructed using palynology (pollen and dinocysts) and supported by particle size analysis and XRF/stable isotopes. Pollen is used to interpret terrestrial vegetation successions (as a proxy for catchment climate) and dinocysts for conditions within the water body itself (linked to degree of fresh water input, base level variation and inter-basin connectivity). The Akchagyl pollen record shows cyclic vegetation patterns related to obliquity-scale climate forcing. Dinocysts and geochemical proxies also respond to climatic influence, but their behaviour is more strongly influenced by connectivity between the Caspian Sea and adjacent basins. New methods were explored to constrain problems of reworking in deltaic facies deposited during the Pliocene. In particular, quality of the environmental signal was assessed using fluorescence microscopy, as delta assemblages can be dominated by older reworked palynomorphs, obscuring the contemporary environmental signal. Serious issues relating to depositional environments and taphonomy within the Productive Series were highlighted. This must be understood before the local

  19. IR-RF dating on K-feldspar: tracing environmental changes in the Middle Pleistocene?

    NASA Astrophysics Data System (ADS)

    Kreutzer, Sebastian; Frouin, Marine; Krishna Murari, Madhav; Fuchs, Markus; Mercier, Norbert

    2017-04-01

    In Quaternary sciences, luminescence dating (OSL, TL, RF) yielded paramount importance due to its capability to trace the geomorphological process itself. However, every method has its own limitation and, e.g., the choice of a mineral depends on its local availability and mineral specific characteristic. Since quartz has been proved as reliable dosimeter, but its usual dose saturation level of ca. 150 Gy might be not sufficient in particular cases, feldspar grains are preferred for dating events where higher saturation limits are desired or quartz is not available. However, feldspar suffers from anomalous fading and the efforts undertaken during the last decades to overcome this challenge varied in their success. By contrast, infrared radiofluorescence (IR-RF) of K-feldspar (Trautmann et al., 1999) seems to offer a promising alternative, but until date it has been rarely applied. Likely reasons for this lack of attention are a shortage of commercially available measurement equipment until the recent past and serious methodological doubts that had been raised in the literature (e.g., Buyleart et al., 2012). At the IRAMAT-CRP2A the formerly proposed IR-RF single aliquot regenerative dose (SAR) protocol approach (IRSAR, Erfurt et al., 2003) for K-feldspar grains have been adapted and enhanced (Frouin et al., 2015; Huot et al., 2015; Frouin et al., 2017) using (a) sample adapted bleaching settings and (b) a stimulation at higher temperatures. Together with more recent methodological findings, we present the advantage and the limitations of using the IR-RF dating approach for establishing reliable chronologies on believed Middle Pleistocene sediments. References. Buylaert, J.P., Jain, M., Murray, A.S., Thomsen, K.J., Lapp, T., 2012. IR-RF dating of sand-sized K-feldspar-extracts: A test of accuracy. Radiation Measurements 47, 759-765. Erfurt, G., Krbetschek, M.R., 2003. IRSAR - A single-aliquot regenerative-dose dating protocol applied to the infrared radiofluorescence

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

    2017-04-01

    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.

  6. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. 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.

  8. Middle to Late Pleistocene multi-proxy record of environmental response to climate change from the Vienna Basin, Central Europe (Austria)

    NASA Astrophysics Data System (ADS)

    Salcher, Bernhard C.; Frank-Fellner, Christa; Lomax, Johanna; Preusser, Frank; Ottner, Franz; Scholger, Robert; Wagreich, Michael

    2017-10-01

    Tectonic basins can represent valuable archives of the environmental history. Presented here are the stratigraphy and multi-proxy analyses of two adjacent alluvial fans in the Quaternary active parts of the Vienna Basin, situated at the interface of the Atlantic, European continental and Mediterranean climate. Deposits comprise a sequence of coarse-grained fluvial deposits intercalated by laterally extensive horizons of pedogenically altered fine sediments. To establish palaeoenvironmental reconstructions, fine-grained sequences from a drill core and outcrop data were analysed according to its malacofauna, palaeopedology, susceptibility and sedimentology. The chronological framework is provided by 38 luminescence ages and supported by geomagnetic polarity investigations. Distinct warm periods each associated with a geomagnetic excursion, are recorded in three pedocomplexes formed during the Last Interglacial and two earlier interglacial periods, indicted to correlate with Marine Isotope Stage (MIS) 9 and MIS 11, respectively. Environmental conditions during the early last glacial period (MIS 5, c. 100-70 ka) are reconstructed from mollusc-shell rich overbank fines deposited along a former channel belt, covered by massive sheetflood deposits during MIS 2. Analysed warm phases suggest strong variations in humidity, ranging from steppe to forest dominated environments. The study presents one of the few numerically dated Middle Pleistocene multi-proxy records and one of the most comprehensive malacological datasets covering the early phases of last glacial period of continental Europe.

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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).

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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. © 2016 John Wiley & Sons Ltd/CNRS.

  3. 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.

  4. 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,…

  5. 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,…

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. Ancient DNA reveals that bowhead whale lineages survived Late Pleistocene climate change and habitat shifts.

    PubMed

    Foote, Andrew D; Kaschner, Kristin; Schultze, Sebastian E; Garilao, Cristina; Ho, Simon Y W; Post, Klaas; Higham, Thomas F G; Stokowska, Catherine; van der Es, Henry; Embling, Clare B; Gregersen, Kristian; Johansson, Friederike; Willerslev, Eske; Gilbert, M Thomas P

    2013-01-01

    The climatic changes of the glacial cycles are thought to have been a major driver of population declines and species extinctions. However, studies to date have focused on terrestrial fauna and there is little understanding of how marine species responded to past climate change. Here we show that a true Arctic species, the bowhead whale (Balaena mysticetus), shifted its range and tracked its core suitable habitat northwards during the rapid climate change of the Pleistocene-Holocene transition. Late Pleistocene lineages survived into the Holocene and effective female population size increased rapidly, concurrent with a threefold increase in core suitable habitat. This study highlights that responses to climate change are likely to be species specific and difficult to predict. We estimate that the core suitable habitat of bowhead whales will be almost halved by the end of this century, potentially influencing future population dynamics.

  14. The effects of Pleistocene climate change on biotic differentiation in a montane songbird clade from Wallacea.

    PubMed

    Ng, Nathaniel S R; Wilton, Peter R; Prawiradilaga, Dewi Malia; Tay, Ywee Chieh; Indrawan, Mochamad; Garg, Kritika M; Rheindt, Frank E

    2017-09-01

    The role of Pleistocene Ice Age in tropical diversification is poorly understood, especially in archipelagos, in which glaciation-induced sea level fluctuations may lead to complicated changes in land distribution. To assess how Pleistocene land bridges may have facilitated gene flow in tropical archipelagos, we investigated patterns of diversification in the rarely-collected rusty-bellied fantail Rhipidura teysmanni (Passeriformes: Rhipiduridae) complex from Wallacea using a combination of bioacoustic traits and whole-genome sequencing methods (dd-RADSeq). We report a biogeographic leapfrog pattern in the vocalizations of these birds, and uncover deep genomic divergence among island populations despite the presence of intermittent land connections between some. We demonstrate how rare instances of genetic introgression have affected the evolution of this species complex, and document the presence of double introgressive mitochondrial sweeps, highlighting the dangers of using only mitochondrial DNA in evolutionary research. By applying different tree inference approaches, we demonstrate how concatenation methods can give inaccurate results when investigating divergence in closely-related taxa. Our study highlights high levels of cryptic avian diversity in poorly-explored Wallacea, elucidates complex patterns of Pleistocene climate-mediated diversification in an elusive montane songbird, and suggests that Pleistocene land bridges may have accounted for limited connectivity among montane Wallacean biota. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. Comparative Phylogeography of Ethiopian anurans: impact of the Great Rift Valley and Pleistocene climate change.

    PubMed

    Freilich, Xenia; Anadón, José D; Bukala, Jolanta; Calderon, Ordaliza; Chakraborty, Ronveer; Boissinot, Stéphane

    2016-10-10

    The Ethiopian highlands are a biodiversity hotspot, split by the Great Rift Valley into two distinct systems of plateaus and mountains. The Rift Valley is currently hot and dry and acts as a barrier to gene flow for highland-adapted species. It is however unlikely that the conditions in the Rift were inhospitable to highland species during the entire Pleistocene. To assess the significance of the Ethiopian Rift as a biogeographic barrier as well as the impact Pleistocene climatic changes have had on the evolution of Ethiopian organisms, we performed phylogeographic analyses and developed present and past niche models on seven anuran species with different elevational and ecological preferences. We found that highland species on the east and the west sides of the Rift are genetically differentiated and have not experienced any detectable gene flow for at least 0.4 my. In contrast, species found at elevations lower than 2500 m do not show any population structure. We also determined that highland species have lower effective population sizes than lowland species, which have experienced a large, yet gradual, demographic expansion, starting approximately half a million year ago. The pattern we report here is consistent with the increasingly warmer and drier conditions of the Pleistocene in East Africa, which resulted in the expansion of savanna, the fragmentation of forests and the shrinking of highland habitats. Climatic niche models indicated that the Rift is currently non suitable for most of the studied species, but it could have been a more permeable barrier during the Last Glacial Maximum. However, considering the strong genetic structure of highland species, we hypothesize that the barrier mechanisms at the Rift are not only climatic but also topographical.

  4. 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.

  5. Global Environmental Change Symposium

    NASA Astrophysics Data System (ADS)

    Bush, Susan M.

    The global environmental warming issue has been catapulted to the forefront of media attention as a result of the drought of 1988 and extremely warm temperatures. NASA scientist James Hansen testified last year that the warming trend has begun and that part of the temperature rise is due to gases such as carbon dioxide, methane, and chlorofluro-carbons (CFCs) being released into the atmosphere by human activity.In response to recent scientific speculation on the issue, the National Academy of Sciences, Washington, D.C., hosted the symposium Global Environmental Change April 24 as part of their annual meeting. Speakers included Bert Bolin, University of Stockholm; Robert White, National Academy of Engineering; Stephen Schneider, National Center for Atmospheric Research; and Peter Raven, Missouri Botanical Garden. Moderator was Russell Train, World Wildlife Fund.

  6. The Batagay permafrost mega thaw slump: an environmental archive of the Late Pleistocene continental climate

    NASA Astrophysics Data System (ADS)

    Ashastina, Kseniia; Kienast, Frank; Römermann, Christine; Kuzmina, Svetlana; Diekmann, Bernhard; Schirrmeister, Lutz

    2017-04-01

    Palaeoenvironmental data preserved in permafrost contribute in our understanding of climate changes and their influence on the biocenoses during the Late Quaternary. Here we present cryolithological and palaeoecological results of studies carried out on a newly described permafrost exposure near Batagay about 50 km from Verkhoyansk, Sakha Republic, Russia, the town with the most continental climate recorded in the northern hemisphere. According to Günther et al. (2015), this unique exposure is the biggest mega thaw slump measured so far with the dimensions 800 m wide and 73 m deep. Only sparse data on the exposure are so far published in few articles (Novgorodov et al., 2013; Kunitsky et al., 2013; Ashastina et al., in press; Murton et al., 2016). The site is situated inWest Beringia, the Late Quaternary landmasscovered by tundra steppe and inhabited by diverse mega herbivores. We analyzed sedimentological data, plant macro- and micro-fossils together with insect remains in order to reconstruct the changes in the biome. The temporal frame for the accumulation of the sequence is provided by radiocarbon and optical stimulated luminescence dating, according to which the formation of the sequence started in the late Middle Quaternary. The features of permafrost accumulation and sedimentation give us an opportunity to propose the landscape changes responding to the climatic pulses of Pleistocene at this particular place. The shifts in vegetation from taiga to steppe associations are in a line with stadial and intersadial events. We propose a scheme of permafrost state and vegetation changes and merge it with climate variation during Late Quaternary. Ashastina, K., Schirrmeister, L., Fuchs, M., Kienast, F.: Pleistocene climate characteristics in the most continental part of the northern hemisphere: insights from cryolithological features of the Batagay mega thaw slump in the Siberian Yana Highlands. Climate of the Past, in press. doi: 10.5194/cp-2016-84. Günther, F

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. Deep-sea temperature and ice volume changes across the Pliocene-Pleistocene climate transitions.

    PubMed

    Sosdian, Sindia; Rosenthal, Yair

    2009-07-17

    Earth has undergone profound changes since the late Pliocene, which led to the development [approximately 2.7 million years ago (Ma)] and intensification (approximately 0.9 Ma) of large-scale Northern Hemisphere ice sheets, recorded as transitions in the benthic foraminiferal oxygen isotope (delta18Ob) record. Here we present an orbitally resolved record of deep ocean temperature derived from benthic foraminiferal magnesium/calcium ratios from the North Atlantic, which shows that temperature variations are a substantial portion of the global delta18Ob signal. The record shows two distinct cooling events associated with the late Pliocene (LPT, 2.5 to 3 Ma) and mid-Pleistocene (MPT, 1.2 to 0.85 Ma) climate transitions. Whereas the LPT increase in ice volume is attributed directly to global cooling, the shift to 100,000-year cycles at the MPT is more likely to be a response to an additional change in ice-sheet dynamics.

  12. 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.

  13. Environmental Pollution and Climatic Change,

    DTIC Science & Technology

    anthropogenic modification of global climage , numerical experiment of climatic change , cooling in the northern hemisphere, environmental influence on the Japan...The paper discusses environmental pollution and climatic change . Discussions begin on atmospheric pollution on a global scale, followed by

  14. Evaluating the role of Pleistocene refugia, rivers and environmental variation in the diversification of central African duikers (genera Cephalophus and Philantomba).

    PubMed

    Ntie, Stephan; Davis, Anne R; Hils, Katrin; Mickala, Patrick; Thomassen, Henri A; Morgan, Katy; Vanthomme, Hadrien; Gonder, Mary K; Anthony, Nicola M

    2017-09-06

    This study aims to assess the role that Pleistocene refugia, rivers and local habitat conditions may have played in the evolutionary diversification of three central African duiker species (Cephalophus dorsalis, C. callipygus and Philantomba monticola). Genetic data from geo-referenced feces were collected from a wide range of sites across Central Africa. Historical patterns of population genetic structure were assessed using a ~ 650 bp fragment of the mitochondrial control region and contemporary patterns of genetic differentiation were evaluated using 12 polymorphic microsatellite loci. Mitochondrial analyses revealed that populations of C. callipygus and P. monticola in the Gulf of Guinea refugium are distinct from other populations in west central Africa. All three species exhibit signatures of past population expansion across much of the study area consistent with a history of postglacial expansion. There was no strong evidence for a riverine barrier effect in any of the three species, suggesting that duikers can readily cross major rivers. Generalized dissimilarity models (GDM) showed that environmental variation explains most of the nuclear genetic differentiation in both C. callipygus and P. monticola. The forest-savanna transition across central Cameroon and the Plateaux Batéké region in southeastern Gabon show the highest environmentally-associated turnover in genetic variability. A pattern of genetic differentiation was also evident between the coast and forest interior that may reflect differences in precipitation and/or vegetation. Findings from this study highlight the historical impact of Pleistocene fragmentation and current influence of environmental variation on genetic structure in duikers. Conservation efforts should therefore target areas that harbor as much environmentally-associated genetic variation as possible in order to maximize species' capacity to adapt to environmental change.

  15. Linking changes in Indonesian Throughflow dynamics with the Middle Pleistocene Transition

    NASA Astrophysics Data System (ADS)

    Petrick, B.; Auer, G.; Christensen, B. A.; De Vleeschouwer, D.; Reuning, L.; Martinez-Garcia, A.; Haug, G. H.; Gallagher, S. J.; Fulthorpe, C.; Bogus, K.

    2016-12-01

    The Mid-Pleistocene Transition (MPT; 1.4 - 0.4 Ma) represents a fundamental shift in the Earth's climate state. While there is high-resolution data covering the MPT from globally distributed archives, only sparse evidence exists on changes in the heat exchange between the Pacific and Indian Oceans, representing a crucial part of the global thermohaline circulation. Deciphering the influence of this heat exchange via the Indonesian Throughflow (ITF) is an important step in understanding the causes of the MPT. The Leeuwin Current off Western Australia is directly influenced by the ITF and can be used to reconstruct ITF variability during the MPT. Today, the Leeuwin Current is the only southward flowing eastern boundary current in the southern hemisphere. The onset of the current is unknown, but is proposed to have occurred 1 Ma and was likely related to significant changes in ITF dynamics during the MPT. Here we present the first continuous reconstruction of changes in the Leeuwin Current during the MPT using data from IODP Expedition 356 Site U1460. The site is located at 29°S in the path of the current. We reconstruct paleoenvironmental variability by combining XRF, organic geochemistry, ICP-MS, and XRD data with shipboard results, to reconstruct Leeuwin Current and ITF variability. High sedimentation rates ( 30 cm/ka) at Site U1460 provide the opportunity for high-resolution reconstruction of ITF variability during the MPT. Initial analyses show clear indications that upwelling off Western Australia intensified during the MPT, indicated by increased primary productivity related to increased nutrient levels, from 900-600 ka. Stronger upwelling in turn indicates a reduction in ITF, and thus implies that the heat transport from the Pacific to the Indian Ocean significantly diminished during the MPT. Our results suggest, that reduced heat exchange via the ITF played a major role in forcing the climatic shift towards the 100-kyr icehouse world of the Pleistocene.

  16. Rapid and fundamental paleolimnological changes in Lake Iznik (NW Turkey) during the Holocene/Pleistocene transition: a multiproxy - multisite approach.

    NASA Astrophysics Data System (ADS)

    Gromig, R.; Viehberg, F. A.; Damcı, E.; Ülgen, U. B.; Assonov, S.; Franz, S. O.; Cagatay, M. N.; Litt, T.; Melles, M.; Wagner, B.; Staubwasser, M.

    2016-12-01

    The Marmara region is a key area to investigate the teleconnection and environmental changes of the Black Sea/Eastern Mediterranean Sea and northern hemisphere climate patterns. Lake Iznik, an oligohaline lake, is the largest lake in the Bosphorous region, which holds a continuous sediment archive. A hydro-acoustic survey screened the locations of three sediment cores (5 to 17 m) from previous field campaigns. The longest record reaches back almost to the Campanian Ignimbrite (39.3 cal kyr BP), which represents most likely the lowermost high amplitude reflector in hydro-acoustic profiles. The late Pleistocene ostracode fauna appears low in diversity and evolves abruptly to an abundant monospecific species assemblage of Limnocythere inopinata during the Younger Dryas after substantial alteration in the hydrocarbonate and alkalinity system of Lake Iznik. This distinct change in hydrochemistry is reflected in the appearence of different shell phenotypes and the occurence of a population with sexual reproduction (males/females). Independently, results from stable isotope analyses (δ18O and δ13C) on ostracode shells also suggest that Lake Iznik evolves from a freshwater system to a closed basin sensitive to temperature and precipitation changes.

  17. Responses of Plant Respiration to Pleistocene Changes in Atmospheric CO2 Concentrations

    NASA Astrophysics Data System (ADS)

    Blanc-Betes, E.; Gonzalez-Meler, M.; Gomez-Casanovas, N.; Ward, J. K.

    2008-12-01

    Vegetation plays a crucial role on the terrestrial C cycling through the processes of photosynthesis and respiration. At a global scale, these two processes are essential components of the C cycle, because 30% to 70% of the CO2 fixed by photosynthesis is released back to the atmosphere each year by plant respiration. Therefore, small changes in these two fluxes can have a significant impact on atmospheric CO2 concentration. Changes in CO2 concentrations in the atmosphere have prompted plant evolutionary responses that have resulted in novel physiological photosynthetic adaptations such as the photosynthetic C oxidation pathway or the rise of C4-photosynthesis. However, little is known about the role of respiration on the nature of plant acclimation and adaptation to different CO2 scenarios when the photosynthesis-to-respiration ratio is low. Plant respiration is further complicated by the presence of the alternative pathway that burns photosynthate without producing chemical energy (ATP). Here, we explore the effects of Pleistocene levels of CO2 on plant respiration and on the activity of the alternative pathway. We concentrated in plants that have a low photosynthesis-to-respiration ratio such as plants grown in shade and CAM plants, and on Arabidopsis thaliana plants that were selected at Pleistocene CO2 levels (200ppm), current (360ppm) and projected (680 ppm) atmospheric levels of CO2. Our results, indicate that regardless of the overall respiration response to CO2 levels the activity of the alternative pathway was inversely correlated with atmospheric CO2 concentration in all plants. Because alternative pathway activity is not coupled to ATP production and does not support maintenance or growth processes as effectively as normal respiration, plants exposed to Pleistocene CO2 levels will run respiration more efficiently than plants exposed to current or higher CO2 levels. The effectiveness of respiration can either play a survival role at low CO2 levels, or

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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.

  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. Parallel responses of bees to Pleistocene climate change in three isolated archipelagos of the southwestern Pacific

    PubMed Central

    Groom, Scott V. C.; Stevens, Mark I.; Schwarz, Michael P.

    2014-01-01

    The impacts of glacial cycles on the geographical distribution and size of populations have been explored for numerous terrestrial and marine taxa. However, most studies have focused on high latitudes, with only a few focused on the response of biota to the last glacial maximum (LGM) in equatorial regions. Here, we examine how population sizes of key bee fauna in the southwest Pacific archipelagos of Fiji, Vanuatu and Samoa have fluctuated over the Quaternary. We show that all three island faunas suffered massive population declines, roughly corresponding in time to the LGM, followed by rapid expansion post-LGM. Our data therefore suggest that Pleistocene climate change has had major impacts across a very broad tropical region. While other studies indicate widespread Holarctic effects of the LGM, our data suggest a much wider range of latitudes, extending to the tropics, where these climate change repercussions were important. As key pollinators, the inferred changes in these bee faunas may have been critical in the development of the diverse Pacific island flora. The magnitude of these responses indicates future climate change scenarios may have alarming consequences for Pacific island systems involving pollinator-dependent plant communities and agricultural crops. PMID:24807250

  5. Parallel responses of bees to Pleistocene climate change in three isolated archipelagos of the southwestern Pacific.

    PubMed

    Groom, Scott V C; Stevens, Mark I; Schwarz, Michael P

    2014-06-22

    The impacts of glacial cycles on the geographical distribution and size of populations have been explored for numerous terrestrial and marine taxa. However, most studies have focused on high latitudes, with only a few focused on the response of biota to the last glacial maximum (LGM) in equatorial regions. Here, we examine how population sizes of key bee fauna in the southwest Pacific archipelagos of Fiji, Vanuatu and Samoa have fluctuated over the Quaternary. We show that all three island faunas suffered massive population declines, roughly corresponding in time to the LGM, followed by rapid expansion post-LGM. Our data therefore suggest that Pleistocene climate change has had major impacts across a very broad tropical region. While other studies indicate widespread Holarctic effects of the LGM, our data suggest a much wider range of latitudes, extending to the tropics, where these climate change repercussions were important. As key pollinators, the inferred changes in these bee faunas may have been critical in the development of the diverse Pacific island flora. The magnitude of these responses indicates future climate change scenarios may have alarming consequences for Pacific island systems involving pollinator-dependent plant communities and agricultural crops.

  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

    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.

  8. 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.

  9. 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.

  10. 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.

  11. Late Pleistocene ecological, environmental and climatic reconstruction based on megafauna stable isotopes from northwestern Chilean Patagonia

    NASA Astrophysics Data System (ADS)

    González-Guarda, Erwin; Domingo, Laura; Tornero, Carlos; Pino, Mario; Hernández Fernández, Manuel; Sevilla, Paloma; Villavicencio, Natalia; Agustí, Jordi

    2017-08-01

    Stable isotope analyses have been performed on the bioapatite (δ13C; δ18O) and collagen (δ13C; δ15N) of four late Pleistocene South American megafaunal taxa (Notiomastodon platensis, Equus andium, cf. Hemiauchenia paradoxa and Xenarthra indet.) to evaluate paleoclimatic and paleoenvironmental conditions as well as paleoecological features of this time period. The analyzed megafauna was found at several locations in the northwestern Chilean Patagonia (38°-42°S, 74°-71°W). The bioapatite δ13C values indicated the presence of C3 vegetation ranging from forestal to woodland areas. The collagen δ15N values pointed to temperate and humid ecosystems, and to the consumption of shrubs, trees, grasses and sedges. Mean annual temperatures estimated from bioapatite δ18OPO4 values show a similarity to modern temperatures and suggested that the megafauna under study may have lived during warm stages (interstadials) of the late Pleistocene. When comparing our results with those obtained from other South American regions, we find that the diet of this particular Chilean megafauna appears to have been more influenced by resource availability than by the potential dietary range of the taxa.

  12. Sandstone provenance and detrital zircon geochronology record changes in Plio-Pleistocene tectonism of the Southern Cascadia forearc

    NASA Astrophysics Data System (ADS)

    Garcia, M. J.; Michalak, M.; Hourigan, J. K.

    2016-12-01

    The Cascadia Subduction Zone (CSZ) in the Pacific NW is defined by subducting oceanic lithosphere (Juan de Fuca-Gorda) beneath the North American Plate, from British Colombia to Northern California. In the Southern CSZ, the forearc is characterized by high topography of the Klamath Mountain Province west of the volcanic arc, the lower lying Northern Coast Ranges, comprising Cretaceous through Miocene Franciscan Formation, and structurally controlled coastal basins of Pliocene-Pleistocene fluvial-marine sedimentary rocks. The southernmost CSZ is affected by northward migration of the Mendocino Triple Junction; high rates of rock uplift and tectonically controlled drainage patterns are evident of its passage spatially and temporally. While provenance sources for early-to-mid Tertiary sedimentary units of the Franciscan are well-described, less is known about provenance sources in Plio-Pleistocene time, and how changes in regional tectonics, such as the migration of the MTJ, and uplift of the Klamath Mountains, may have affected sediment dispersal. Previous work and our preliminary results indicate that the Plio-Pleistocene Wildcat Group of the Eel River basin is characterized by distant sources. Aalto et al., (1998) and Moley (1997) use detrital mica Ar/Ar ages and petrofacies analyses of the Wildcat to hypothesize provenance from the distant Idaho Batholith. We test this hypothesis using detrital zircon U-Pb geochronology, and present eight new detrital sample ages from Plio-Pleistocene sedimentary basins along the coastal margin north of the MTJ. These results are used to inform paleographic reconstructions of Pliocene-Pleistocene regional topography associated with the dynamic tectonics of Southern Cascadia.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. Environmentalism and Social Change.

    ERIC Educational Resources Information Center

    Tiemann, Adrian R.

    A high level of individual concern with environmental issues characterizes the ecological crisis of the 1970s. In spite of this increased public involvement, however, many basic problems facing humans as they interact with the environment have remained constant throughout history. For example, the sometimes conflicting concepts of scarcity,…

  18. 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

  19. Comment on "Deep-sea temperature and ice volume changes across the Pliocene-Pleistocene climate transitions".

    PubMed

    Yu, Jimin; Broecker, Wally S

    2010-06-18

    Sosdian and Rosenthal (Reports, 17 July 2009, p. 306) used magnesium/calcium ratios in benthic foraminifera from the North Atlantic to reconstruct past bottom-water temperatures. They suggested that both ice volume change and ice-sheet dynamics played important roles during the late Pliocene and mid-Pleistocene climate transitions. We present evidence that their record of deep ocean temperature is not reliable, thus raising doubts about their conclusions.

  20. Late Pleistocene-Holocene vegetation and climate change in the Middle Kalahari, Lake Ngami, Botswana

    NASA Astrophysics Data System (ADS)

    Cordova, Carlos E.; Scott, Louis; Chase, Brian M.; Chevalier, Manuel

    2017-09-01

    Pollen, spores, and microscopic charcoal from a sediment core from Lake Ngami, in the Middle Kalahari, reflect paleovegetation and paleoclimatic conditions over the last 16,600 cal years BP. The location of Lake Ngami allows for the receipt of moisture sourced from the Indian and/or Atlantic oceans, which may have influenced local rainfall or long distance water transport via the Okavango system. We interpret results of statistical analyses of the pollen data as showing a complex, dynamic system wherein variability in tropical convective systems and local forcing mechanisms influence hydrological changes. Our reconstructions show three primary phases in the regional precipitation regime: 1) an early period of high but fluctuating summer rainfall under relatively cool conditions from ∼16,600-12,500 cal BP, with reduced tree to herb and shrub ratio; 2) an episode of significantly reduced rainfall centered around c. 11,400 cal BP, characterized by an increase in xeric Asteraceae pollen, but persistent aquatic elements, suggesting less rainfall but cool conditions and lower evaporation that maintained water in the basin; and 3) a longer phase of high, but fluctuating rainfall from ∼9000 cal BP to present with more woody savanna vegetation (Vachellia (Acacia) and Combretaceae). We propose a model to relate these changes to increased Indian Ocean-sourced moisture in the late Pleistocene due to a southerly position of the African rain belt, a northerly contraction of tropical systems that immediately followed the Younger Dryas, and a subsequent dominance of local insolation forcing, modulated by changes in the SE Atlantic basin.

  1. 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.

  2. 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

  3. Ecological effects of environmental change.

    PubMed

    Luque, Gloria M; Hochberg, Michael E; Holyoak, Marcel; Hossaert, Martine; Gaill, Françoise; Courchamp, Franck

    2013-05-01

    This Special Issue of Ecology Letters presents contributions from an international meeting organised by Centre National de la Recherche Scientifique (CNRS) and Ecology Letters on the broad theme of ecological effects of global environmental change. The objectives of these articles are to synthesise, hypothesise and illustrate the ecological effects of environmental change drivers and their interactions, including habitat loss and fragmentation, pollution, invasive species and climate change. A range of disciplines is represented, including stoichiometry, cell biology, genetics, evolution and biodiversity conservation. The authors emphasise the need to account for several key ecological factors and different spatial and temporal scales in global change research. They also stress the importance of ecosystem complexity through approaches such as functional group and network analyses, and of mechanisms and predictive models with respect to environmental responses to global change across an ecological continuum: population, communities and ecosystems. Lastly, these articles provide important insights and recommendations for environmental conservation and management, as well as highlighting future research priorities.

  4. 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

  5. The integration of multiple independent data reveals an unusual response to Pleistocene climatic changes in the hard tick Ixodes ricinus.

    PubMed

    Porretta, Daniele; Mastrantonio, Valentina; Mona, Stefano; Epis, Sara; Montagna, Matteo; Sassera, Davide; Bandi, Claudio; Urbanelli, Sandra

    2013-03-01

    In the last few years, improved analytical tools and the integration of genetic data with multiple sources of information have shown that temperate species exhibited more complex responses to ice ages than previously thought. In this study, we investigated how Pleistocene climatic changes affected the current distribution and genetic diversity of European populations of the tick Ixodes ricinus, an ectoparasite with high ecological plasticity. We first used mitochondrial and nuclear genetic markers to investigate the phylogeographic structure of the species and its Pleistocene history using coalescent-based methods; then we used species distribution modelling to infer the climatic niche of the species at last glacial maximum; finally, we reviewed the literature on the I. ricinus hosts to identify the locations of their glacial refugia. Our results support the scenario that during the last glacial phase, I. ricinus never experienced a prolonged allopatric divergence in separate glacial refugia, but persisted with interconnected populations across Southern and Central Europe. The generalist behaviour in host choice of I. ricinus would have played a major role in maintaining connections between its populations. Although most of the hosts persisted in separate refugia, from the point of view of I. ricinus, they represented a continuity of 'bridges' among populations. Our study highlights the importance of species-specific ecology in affecting responses to Pleistocene glacial-interglacial cycles. Together with other cases in Europe and elsewhere, it contributes to setting new hypotheses on how species with wide ecological plasticity coped with Pleistocene climatic changes. © 2013 Blackwell Publishing Ltd.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Changes in Equatorial Atlantic Ocean Thermohaline Circulation Across the Mid-Pleistocene Transition

    NASA Astrophysics Data System (ADS)

    Yehudai, M.; Kim, J.; Seguí, M. J.; Goldstein, S. L.; Pena, L. D.; Haynes, L.; Hoenisch, B.; Farmer, J. R.; Ford, H. L.; Raymo, M. E.; Bickert, T.

    2016-12-01

    The Mid-Pleistocene Transition (MPT) marked a change in the duration of glacial-interglacial cycles from 41 to 100kyr between 1.3-0.7 Ma. A recent study (Pena and Goldstein, Science, 2014) from the Southern Atlantic Ocean found evidence for major disruptions in the global thermohaline circulation (THC) between MIS 25-21 ( 950-850ka), which may have triggered intensified glacial periods and the onset of the 100 kyr cycles. We report new Nd isotope data on Fe-Mn oxide encrusted foraminifera and fish debris from ODP Site 926 (3.719N, 42.908W, 3598m) between 1.2-0.4 Ma, in order to evaluate changes in the THC in the equatorial Atlantic, through comparison with North and South Atlantic sites. The ODP 926 ɛNd values fall in-between those in the North Atlantic (DSDP 607) and South Atlantic (ODP 1088 and 1090) throughout the studied interval, consistent with mixing between northern and southern end-members, and supporting the interpretation that the data represent the THC signal at this site. Pre-MPT data show smaller glacial-interglacial differences compared to the greater post-MPT glacial-interglacial variability. As Pena and Goldstein (2014) observed in the South Atlantic, during MIS 23 at 900 ka, ɛNd values do not shift significantly toward North Atlantic more negative values, consistent with a weak THC through this critical weak interglacial. Comparing ODP 926 and DSDP 607 data, ɛNd values converge during most interglacial peaks (excepting MIS 23) and diverge otherwise. This observation indicates that northern-sourced water masses dominate the site during peak interglacials, and confirms that the THC has been strongest during peak interglacials throughout the studied interval. Otherwise, diverging ɛNd values indicate a stronger southern-source signal and weaker northern-source signal at the ODP 926 site. This confirms that there was an active but variable THC system before, during, and after the MPT, with stronger deep water export from the North Atlantic during

  12. 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.

  13. 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

  14. Climate Change, Genetics or Human Choice: Why Were the Shells of Mankind's Earliest Ornament Larger in the Pleistocene Than in the Holocene?

    PubMed Central

    Teske, Peter R.; Papadopoulos, Isabelle; McQuaid, Christopher D.; Newman, Brent K.; Barker, Nigel P.

    2007-01-01

    Background The southern African tick shell, Nassarius kraussianus (Dunker, 1846), has been identified as being the earliest known ornamental object used by human beings. Shell beads dated from ∼75,000 years ago (Pleistocene era) were found in a cave located on South Africa's south coast. Beads made from N. kraussianus shells have also been found in deposits in this region dating from the beginning of the Holocene era (<10,000 years ago). These younger shells were significantly smaller, a phenomenon that has been attributed to a change in human preference. Methodology/Principal Findings We investigated two alternative hypotheses explaining the difference in shell size: a) N. kraussianus comprises at least two genetic lineages that differ in size; b) the difference in shell size is due to phenotypic plasticity and is a function of environmental conditions. To test these hypotheses, we first reconstructed the species' phylogeographic history, and second, we measured the shell sizes of extant individuals throughout South Africa. Although two genetic lineages were identified, the sharing of haplotypes between these suggests that there is no genetic basis for the size differences. Extant individuals from the cool temperate west coast had significantly larger shells than populations in the remainder of the country, suggesting that N. kraussianus grows to a larger size in colder water. Conclusion/Significance The decrease in fossil shell size from Pleistocene to Holocene was likely due to increased temperatures as a result of climate change at the beginning of the present interglacial period. We hypothesise that the sizes of N. kraussianus fossil shells can therefore serve as indicators of the climatic conditions that were prevalent in a particular region at the time when they were deposited. Moreover, N. kraussianus could serve as a biomonitor to study the impacts of future climate change on coastal biota in southern Africa. PMID:17637830

  15. 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.

  16. 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.

  17. Plio-Pleistocene changes in the vegetation of central North Africa

    NASA Astrophysics Data System (ADS)

    Castaneda, I. S.; Phu, V.; Urann, B.

    2013-12-01

    The area of central North Africa (including the Sahara and the Sahel) is sensitive to migrations of the intertropical rainbelt and has experienced dramatic, and possibly abrupt, shifts between wet and arid conditions in the past. For example, during the humid period of the early Holocene, the region that is presently the Sahara desert was vegetated and contained permanent lakes, and was occupied by human populations (e.g. Kuper and Kröpelin, 2006). In this study, we investigate the hydrology of central North Africa during the Plio-Pleistocene (4-0.5 Ma), a period during which a number of key steps in hominin evolution occurred. ODP site 660 is located in the tropical NE Atlantic Ocean (offshore West Africa) and receives dust from central North Africa, which is transported offshore by the African Easterly Jet. Plant leaf waxes (n-alkanes) contained in this dust provide information on the type of vegetation present , which in turn, can be used to examine hydrological variability because in tropical Africa the large scale distribution of vegetation utilizing the C3 (mainly trees) vs. C4 (grasses and warm season sedges) photosynthetic pathways mainly depends on aridity (precipitation) (e.g. Schefuss et al., 2003). Here, we examine the carbon (δ13C) and deuterium (δD) isotopic composition of plant leaf waxes, proxies for vegetation type (C3 vs. C4 plants) and precipitation amount, respectively. We also examine sea surface temperature variability using the alkenone Uk'37 Index as several studies have demonstrated close ties between sea surface temperature variability and hydrological conditions in N Africa during the late Pleistocene and Holocene. Results of this study further support a close link between SST and hydrological conditions in the Sahel during the past 4 Ma while also highlighting regional differences in aridity between Plio-Pleistocene records of western, eastern and southern Africa.

  18. Middle to Late Pleistocene environmental and climatic reconstruction of the human occurrence at Grotta Maggiore di San Bernardino (Vicenza, Italy) through the small-mammal assemblage

    NASA Astrophysics Data System (ADS)

    López-García, Juan Manuel; Luzi, Elisa; Peresani, Marco

    2017-07-01

    Grotta Maggiore di San Bernardino, located at an altitude of 135 m a.s.l. in the Berici Hills in northeastern Italy, is an archaeological site with a discontinuous sedimentary sequence dating from Marine Isotope Stage 7 (MIS 7) to MIS 3. In this paper we present for the first time a palaeoenvironmental and palaeoclimatic reconstruction of the sequence based on small-mammal (insectivore, bat and rodent) assemblages. Coupled with biochronological data and absolute dating together with previous studies on large mammals, birds and other studies on small mammals and pollen from comparable time-spans in Italy, the results enable us clearly to identify distinct climatic periods: the end of MIS 7 (7c to 7a) in units VIII-VII, MIS 5d in unit V, and probably MIS 5b in unit IV and an indeterminate MIS 3 interstadial in units III-II. Finally, the study shows that the early Middle Palaeolithic human occupation in Italy occurs during mild and temperate sub-stages of MIS 7 and that human groups with the same techno-cultural background (Mousterian) were well adapted to the changing environmental and climatic conditions of the Middle to Late Pleistocene in this part of southern Europe.

  19. 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

  20. 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

  1. Paleobiogeographic Changes at the Pleistocene-Holocene Boundary near Pintwater Cave, Southern Nevada

    NASA Astrophysics Data System (ADS)

    Hockett, Bryan Scott

    2000-03-01

    In 1996, approximately 70,000 mammal and lizard bones were recovered from Pintwater Cave in the northern Mojave Desert of southern Nevada. These bones date between 32,000 and 7350 14C yr B.P. Between 32,000 and 10,100 14C yr B.P. the local fauna consisted of a mix of xeric- and cool/mesic-adapted species. Ochotona princeps and Thomomys talpoides then occupied the region, although these animals were extirpated by the onset of the middle Holocene. Sauromalus obesus and Dipodomys deserti probably migrated to the region during the latest Pleistocene. Dipsosaurus dorsalis entered the Pintwater Cave record after 8000 14C yr B.P. Consistent with climatic interpretations for the northern Great Basin, these data suggest a cool and moist latest Pleistocene climate for the northern Mojave Desert. In contrast to the northern Great Basin, however, this region experienced predictable summer precipitation coupled with increasingly warmer winters by 10,100 14C yr B.P. In both regions, the warm middle Holocene began ca. 8300 14C yr B.P. However, whereas the northern Great Basin probably experienced warm and dry conditions at that time, the northern Mojave Desert remained warm with relatively predictable summer precipitation. The modern northern Mojave Desert biota probably was not established until after 8300 14C yr B.P.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. Paleoceanographic Change at the Eastern Margin of the Western Pacific Warm Pool during the Mid-Pleistocene Transition

    NASA Astrophysics Data System (ADS)

    Seo, Inah; Lee, Yong Il; Yoo, Chan Min; Hyeong, Kiseong; Kim, Wonnyon

    2015-04-01

    To investigate evolution of the Western Pacific Warm Pool (WPWP) during Pleistocene, a 560-cm-long sediment core was retrieved at the eastern margin of WPWP (PC090302, 5°53'N 177°26'W, 4136 m). The core sediment was analyzed for the stable isotope composition (δ18O and δ13C) of planktonic foraminifera G. sacculifer, CaCO3 and biogenic silica (BSi) contents, and the amount of coarse-size fraction (CSF; >63 μm, represented mostly by foraminifera). The depositional age was defined for the last ~1 Myr by two geomagnetic reversals; Matuyama and Jaramilo. The analyzed attributes show an abrupt change across the ~800 kyr boundary. The δ18O and δ13C compositions of G. sacculifer have shifted to the lighter values after 800 ka. Foraminiferal tests dominate the carbonate fraction in the younger interval with CSF of 15-35 wt%, while coccoliths are predominant in older intervals. The overall sedimentation rate and BSi content are also high in the lower interval, suggesting the permanent changes in primary production of the ocean surface across the ~800 kyr boundary. The enhanced production of BSi and coccoliths indicates fertile surface ocean condition at the study site for 800 ka to 1 Ma, coinciding with the Mid-Pleistocene Transition (MPT) marked by a shift in the glacial-interglacial climatic variability from 41-kyr cycle to high-amplitude 100-kyr cycle. The possible explanation of the elevated surface production is the enhanced Hadley and Walker circulation during the MPT and subsequent intensification of equatorial upwelling. To support this interpretation, analyses for lipid biomarkers are on progress to delineate changes in sea surface temperature and the relative contribution of primary producers in the study site.

  13. 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

  14. Were sea level changes during the Pleistocene in the South Atlantic Coastal Plain a driver of speciation in Petunia (Solanaceae)?

    PubMed

    Ramos-Fregonezi, Aline M C; Fregonezi, Jeferson N; Cybis, Gabriela B; Fagundes, Nelson J R; Bonatto, Sandro L; Freitas, Loreta B

    2015-05-20

    Quaternary climatic changes led to variations in sea level and these variations played a significant role in the generation of marine terrace deposits in the South Atlantic Coastal Plain. The main consequence of the increase in sea level was local extinction or population displacement, such that coastal species would be found around the new coastline. Our main goal was to investigate the effects of sea level changes on the geographical structure and variability of genetic lineages from a Petunia species endemic to the South Atlantic Coastal Plain. We employed a phylogeographic approach based on plastid sequences obtained from individuals collected from the complete geographic distribution of Petunia integrifolia ssp. depauperata and its sister group. We used population genetics tests to evaluate the degree of genetic variation and structure among and within populations, and we used haplotype network analysis and Bayesian phylogenetic methods to estimate divergence times and population growth. We observed three major genetic lineages whose geographical distribution may be related to different transgression/regression events that occurred in this region during the Pleistocene. The divergence time between the monophyletic group P. integrifolia ssp. depauperata and its sister group (P. integrifolia ssp. integrifolia) was compatible with geological estimates of the availability of the coastal plain. Similarly, the origin of each genetic lineage is congruent with geological estimates of habitat availability. Diversification of P. integrifolia ssp. depauperata possibly occurred as a consequence of the marine transgression/regression cycles during the Pleistocene. In periods of high sea level, plants were most likely restricted to a refuge area corresponding to fossil dunes and granitic hills, from which they colonized the coast once the sea level came down. The modern pattern of lineage geographical distribution and population variation was established by a range

  15. An "inverse" modelling approach to reconstruct CO2 and climate change during the Pliocene-Pleistocene transition

    NASA Astrophysics Data System (ADS)

    Willeit, Matteo; Ganopolski, Andrey; Calov, Reinhard

    2014-05-01

    The Pliocene-Pleistocene Transition (PPT) happened at around 2.7 million years ago (Ma). This transition culminated a gradual cooling trend observed during the end of the Pliocene and was characterized by appearance of the large continental ice sheets over northern Eurasia and North America. There is evidence from reconstructions that the PPT was accompanied and possibly caused by a decrease in atmospheric CO2 from values indicatively between 350 and 400 ppm during the late Pliocene, around 3 Ma, to values closer to the preindustrial value of 280 ppm, but uncertainties in CO2 reconstructions for this period of time remain large. In this study, we present the best guess CO2 scenario for the interval from 3.3 to 2.4 Ma, which is the most consistent with benthic δ18O, tropical surface ocean temperatures and other paleoclimate records. With the CLIMBER-2ice Earth system model of intermediate complexity, including interactive ice-sheets and driven by orbital forcing, we run a large ensemble of model simulations with different prescribed CO2 pathways that are compatible with the broad range from reconstructions. We then define a metric to quantify the model-data agreement. Minimizing the data-model mismatch allows us to infer the CO2 pathway which results in the best fit of the model to the data. Assuming that other external forcings, e.g. topography changes, played only a secondary role for the PPT and that the model performs reasonably well at simulating the response of climate and ice volume to orbital forcing and prescribed CO2, we obtain an independent estimate of the CO2 evolution during the Pliocene-Pleistocene transition. Our results confirm that CO2 evolution alone can explain major changes in climate dynamics during PPT.

  16. 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

  17. 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

  18. 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. © The American Genetic Association 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  5. 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.

  6. 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. PMID:28397796

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

    PubMed

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

    2017-04-11

    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.

  8. 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.

  9. Eccentricity and global cooling forced Quaternary tropical climate changes and mid-Pleistocene transition

    NASA Astrophysics Data System (ADS)

    Yu, Z.; Wan, S.; Christophe, C.; Song, L.; Sun, H.; Xu, Z.; Li, A.; Li, T.

    2016-12-01

    The El Niño/Southern Oscillation (ENSO) activity and Pacific Walker Circulation are controlled by the zonal sea surface temperature (SST) gradient over the tropical western-eastern Pacific Ocean, and the associated pressure gradient (Julian and Chervin, 1978). Such increased zonal SST gradient since early Pleistocene was primarily triggered by the decreasing SST in the equatorial east Pacific, as the SST of the Western Pacific Warm Pool (WPWP) remained stable (Liu and Herbert, 2004; de Garidel-Thoron et al., 2005). However, the driven mechanism of this cooling in the equatorial east Pacific (EEP) and its role in the MPT is not clear. Here we present the high-resolution clay mineral and grain-size records spanning the last 2.36 Myr, obtained from the core MD06-3050 in the West Philippine Sea. Our results indicate that the rainfall intensification on Luzon Island are coeval with a reduction in precipitation over central China and an increase in zonal SST gradient in the equatorial Pacific Ocean, implying a reinforcement of La Niña-like conditions. In contrast, periods of reduced of rainfall in Luzon Island are associated with higher precipitation in central China and a weakening zonal SST gradient in the equatorial Pacific Ocean, thereby suggesting the development of dominant El Niño-like conditions. In contrast with a previously suggested smaller influence of Earth's orbital eccentricity on the global isolation, our results demonstrated that a combined effect of eccentricity modulated tropical isolation and global cooling dominated the long-term variations of SST in the EEP. The continued decreased zonal SST gradient and subsequent intensified Pacific Walker Circulation in between 1.2 to 0.8 Myr ago, which might alter the meridional heat and moisture transport and trigger the MPT(McClymont and Rosell-Melé, 2005), was induced by a weaken eccentricity modulated tropical isolation and enhanced high-latitude cooling. Such mechanism may act as a dominate inducement

  10. 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

  11. 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).

  12. 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

  13. Middle Pleistocene palaeoenvironmental changes of the eastern Canary Islands - revealed by the Mála dune-palaeosol-sequence at Lanzarote (Canary Islands)

    NASA Astrophysics Data System (ADS)

    von Suchodoletz, H.; Zöller, L.; Hilgers, A.; Radtke, U.; Faust, D.

    2012-04-01

    The Canary Islands are located at the transition between the Mediterranean and the Saharan climate off NW-Africa. Thus, they are a key area for the investigation of palaeoenvironmental changes. Several terrestrial studies investigated the palaeoenvironmental development of that region during the later part of the last glacial cycle. However, apart from recent investigations of "vega" sediments on Lanzarote Island (Suchodoletz et al. 2010) the palaeoenvironmental evolution during the Middle Pleistocene is hardly studied yet, basically due to the lack of reliable geochronological data. The Mála dune-palaeosol-sequence is located in the north of Lanzarote. It consists of marine shell detritus originally blown out from the insular shelf during periods of low global sea level, and to a small part of Saharan dust and fine quartz sand. The aeolian layers are intercalated with up to eight silty-clayey palaeosol horizons. Unlike the dune sands, the soils indicate stable landscape conditions with trapping of Saharan dust. Using a combination of ESR and luminescence dating techniques, we are able to place this sequence into the Middle Pleistocene, in contrast to former investigations based on 14C datings postulating a Late Pleistocene age (Ortiz et al. 2006). As a consequence, clayey-silty palaeosols represent periods of stable landscape conditions in the Canarian region during the Middle Pleistocene, which we compare with marine palaeoclimatic studies from the area.

  14. 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.

  15. 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.

  16. 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

  17. The Changing Face of Plio-Pleistocene Reef Margins: Results of the Dominican Republic Drilling Project (DRDP)

    NASA Astrophysics Data System (ADS)

    Klaus, J.; McNeill, D. F.; Díaz, V.; Swart, P. K.; Pourmand, A.; Grasmueck, M.; Eberli, G. P.

    2013-12-01

    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. However, the dominance and high accretion potential of acroporid reefs has a relatively recent geologic origin. 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 a transect of the southern coast of the DR in conjunction with over 20 km of ground penetrating radar (GPR) lines. New age constraints based on U/Th geochronometry and radiogenic Sr isotopes, combined with depositional lithofacies, faunal indicators, stable isotope profiles and GPR data have allowed us to correlate between wells and define the internal anatomy and stratal geometry of the individual reef sigmoids and sigmoid sets. The stacking of these sigmoid-shaped reefs produce lateral progradation of approximately 15 km with geometries that generally follow the highstand systems tract model of Pomar and Ward (1994). Based on existing age models eccentricity (high amplitude 100 kyr) sigmoids display increased aggradation and progradation potential compared to reef cycles driven by obliquity (41 kyr).

  18. 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

  19. Influence of the Indian monsoon and the subtropical jet on climate change on the Tibetan Plateau since the late Pleistocene

    NASA Astrophysics Data System (ADS)

    Hou, Juzhi; D'Andrea, William J.; Wang, Mingda; He, Yue; Liang, Jie

    2017-05-01

    Precipitation atop the Tibetan Plateau (TP) is delivered by the Indian summer monsoon, the Asian summer monsoon, and weather systems associated with the subtropical westerly jet. Variations in the relative importance of the monsoon systems and the westerly jet are hypothesized to have occurred at decadal, millennial and glacial-interglacial scales. However, paleoclimate observations based on explicit climate proxies are still scarce, limiting our understanding of the mechanisms of Holocene climate variability on the Tibetan Plateau (TP). Here we present three independently dated compound specific hydrogen isotope records of sedimentary leaf waxes from lakes on the TP, Bangong Co, Lake Qinghai and Linggo Co. The leaf wax δD records reflect isotopes in precipitation, and we combine these observations with existing isotopic and hydrological data to investigate variations in the influence of the summer monsoon and the westerly jet on the moisture budget of the TP since the Late Pleistocene. δD values of precipitation at all three lakes were relatively positive during the Late Pleistocene indicating a weakened summer monsoon. During the early and mid-Holocene, δD values of precipitation at the three lakes were relatively negative, suggesting the importance of summer monsoon. During the middle to late Holocene, δD values at Bangong Co and Lake Qinghai gradually increased with superimposed episodes of short term of δD variability. However, at Linggo Co in the northern TP, periods of more positive δD values of precipitation correspond to wetter intervals inferred from lake level high stands, and likely reflect variations in moisture associated with the westerly jet. Thus, the δD records at Linggo Co imply the lesser importance of summer monsoon moisture in the hydrologic budget of the northern TP. Collectively, the hydrogen isotope records at these three lakes document millennial and centennial scale variations in the strength of the summer monsoon systems and

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Late Pleistocene Environments of the Central Ukraine

    NASA Astrophysics Data System (ADS)

    Rousseau, Denis-Didier; Gerasimenko, Natalia; Matviischina, Zhanna; Kukla, George

    2001-11-01

    The Vyazivok loess sequence from the Dnieper Plain, Ukraine, documents regional environmental changes during the late Pleistocene and Holocene. Pedological and palynological analyses and low-field magnetic susceptibility document changes from dense temperate forest during the last interglacial maximum to open, harsh, loess-steppe during the latest Pleistocene. The Vyazivok section overlies hillwash derived from a lower Pleistocene terrace and consists of two stratified soil complexes (Kaydaky and Pryluky; marine isotope stage [MIS] 5 equivalent) separated by a layer of eolian dust (Tyasmyn silt). The lower soils in both complexes formed within forest. These soils are overlain by the Uday (MIS4) and Bug (MIS2) loess units, which are separated by boreal soils of the Vytachiv (MIS3) complex. The coldest conditions within the record occurred in the youngest loess. Holocene soils cap the Bug loess. The Vyazivok section shows remarkable similarities with other classical loess sequences in western Europe, the Czech Republic, and Austria. The Kaydaky, Pryluky, and Vytachiv deposits, correlate with the PKIII, PKII, and PKI soil complexes, respectively, of the Czech Republic. The Tyasmyn and Prylyky silt layers correspond to marker horizons from central Europe.

  6. 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

  7. 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).

  8. 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.

  9. The middle Pleistocene transition: characteristics, mechanisms, and implications for long-term changes in atmospheric pCO 2

    NASA Astrophysics Data System (ADS)

    Clark, Peter U.; Archer, David; Pollard, David; Blum, Joel D.; Rial, Jose A.; Brovkin, Victor; Mix, Alan C.; Pisias, Nicklas G.; Roy, Martin

    2006-12-01

    The emergence of low-frequency, high-amplitude, quasi-periodic (˜100-kyr) glacial variability during the middle Pleistocene in the absence of any significant change in orbital forcing indicates a fundamental change internal to the climate system. This middle Pleistocene transition (MPT) began 1250 ka and was complete by 700 ka. Its onset was accompanied by decreases in sea surface temperatures (SSTs) in the North Atlantic and tropical-ocean upwelling regions and by an increase in African and Asian aridity and monsoonal intensity. During the MPT, long-term average ice volume gradually increased by ˜50 m sea-level equivalent, whereas low-frequency ice-volume variability experienced a 100-kyr lull centered on 1000 ka followed by its reappearance ˜900 ka, although as a broad band of power rather than a narrow, persistent 100-kyr cycle. Additional changes at 900 ka indicate this to be an important time during the MPT, beginning with an 80-kyr event of extreme SST cooling followed by the partial recovery and subsequent stabilization of long-term North Atlantic and tropical ocean SSTs, increasing Southern Ocean SST variability primarily associated with warmer interglacials, the loss of permanent subpolar sea-ice cover, and the emergence of low-frequency variability in Pacific SSTs and global deep-ocean circulation. Since 900 ka, ice sheets have been the only component of the climate system to exhibit consistent low-frequency variability. With the exception of a near-universal organization of low-frequency power associated with marine isotope stages 11 and 12, all other components show an inconsistent distribution of power in frequency-time space, suggesting a highly nonlinear system response to orbital and ice-sheet forcing. Most hypotheses for the origin of the MPT invoke a response to a long-term cooling, possibly induced by decreasing atmospheric pCO 2. None of these hypotheses, however, accounts for the geological constraint that the earliest Northern Hemisphere

  10. Is there a component of Pleistocene CO2 change associated with carbonate dissolution cycles?

    NASA Astrophysics Data System (ADS)

    Keir, Robin S.

    1995-10-01

    The only processes which could have decreased atmospheric CO2 during glacial climates without appreciably changing the carbon isotope distribution in the sea appear to be (1) dissolved calcium carbonate input to the ocean, e.g., coral reef buildup and erosion, (2) the ocean solubility pump, due to changes in surface temperature or air-sea exchange, or (3) decreased biological production of calcium carbonate. It is assumed here that one of these mechanisms caused part of the atmospheric CO2 changes recorded in the 200-kyr-long Vostok ice core. Two residual CO2 records are generated by scaling the δ13C difference between planktonic and benthic foraminifera in marine sediment cores to -82 ppm CO2 per 1‰ increase in Δδ13C and subtracting from this the measured CO2 concentration in the ice core. Both residual CO2 records exhibit two broad maximums between about 20-50 ka and 140-200 ka, indicating that during these times, about 40 ppm of the CO2 decrease from interglacial levels cannot be explained by the interaction of the ocean's biological and vertical mixing cycles. The shape of the residual CO2 curve is similar qualitatively to the variation of calcium carbonate in central equatorial Pacific sediments during this time period, which would imply that changes in dissolved carbonate input to the ocean contributed the added component of CO2 change. However, recent models of atmospheric CO2 change in response to changing alkaline input to the ocean exhibit about a 25 to 35 ppm decrease per 1013 mol yr-1 increase in dissolved CaCO3 input. If compensation for the changing input is occurring mostly within an area of about 40 × 106 km² below the lysocline in the Indo-Pacific, the change in carbonate accumulation rate corresponding to a -40 ppm CO2 change would be a minimum of 3 mg cm-2 yr-1. This can be compared to glacial increases of 0.5 to 1.0 mg cm-2 yr-1 during the last 200 kyr in central equatorial Pacific sediments. Thus, the added glacial accumulation of

  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. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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

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

    PubMed

    Rosen, Arlene M; Rivera-Collazo, Isabel

    2012-03-06

    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.

  18. Stable Isotopic Evidence for Latest Pleistocene and Holocene Climatic Change in North-Central Texas

    NASA Astrophysics Data System (ADS)

    Humphrey, John D.; Ferring, C. Reid

    1994-03-01

    A paleoclimatic record for a southern Great Plains locality (the Aubrey Clovis site in north-central Texas) has been established using stable carbon and oxygen isotopes. Detailed composite stratigraphic sections, constrained by 14 C ages, place the age of these deposits between 14,200 and 1600 yr B.P. Calcium carbonate samples of lacustrine and pedogenic origin were analyzed. Oxygen isotopic compositions of most of these in situ carbonates reflect equilibrium precipitation from local meteoric waters. Oxygen isotope values reflect changes in the composition of meteoric waters tied to changes in the isotopic composition of moisture derived from the Gulf of Mexico. Oxygen isotopic variability at the Aubrey site is coincident with marine isotopic records from the gulf that vary due to changes in Laurentide ice sheet volume and meltwater influx. The stable carbon isotopic record, reflecting changing biomass through time, corroborates humid versus arid interpretations based on sedimentology and rates of alluviation. A middle Holocene arid period was in contrast to moist early and late Holocene climate, affirming interpretations of other workers studying southern Great Plains Holocene climate history.

  19. Historical biogeography of longhorn cactus beetles: the influence of Pleistocene climate changes on American desert communities

    Treesearch

    Christopher Irwin Smith; Brian Dorsey Farrell

    2005-01-01

    Mitochondrial sequence data from three species of flightless cactus beetles, Moneilema gigas, M. armatum, and M. appressum, were analyzed. The coalescent models implemented in the program FLUCTUATE were used to test the hypothesis that these species experienced range changes following the end of the last glacial...

  20. 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

  1. 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

  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 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

  3. 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.

  4. Changes in northeast African hydrology and vegetation associated with Pliocene–Pleistocene sapropel cycles

    PubMed Central

    Rose, Cassaundra; Polissar, Pratigya J.; Tierney, Jessica E.; Filley, Timothy

    2016-01-01

    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 δ13Cwax 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 δ13Cwax 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

  5. 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

  6. 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.

  7. New data on the Late Pleistocene and Holocene glacial, climate and relative sea-level changes at Fildes Peninsula, King George Island (South Shetlands Islands, West Antarctica)

    NASA Astrophysics Data System (ADS)

    Verkulich, Sergey; Pushina, Zina; Tatur, Andrej

    2010-05-01

    New data on the Late Pleistocene and Holocene glacial, climate and relative sea-level changes at Fildes Peninsula, King George Island (South Shetlands Islands, West Antarctica) Verkulich S. R. (Arctic and Antarctic Research Institute, St. Petersburg, Russia) Pushina Z.V. (Arctic and Antarctic Research Institute, St. Petersburg, Russia) Tatur A. (Department of Antarctic Biology, Polish Academy of Sciences, Warsaw, Poland) During the 2008-2009 austral summer, co-operative Russian - Polish paleogeographical investigations allowed to refine the understanding of the past environmental events at Fildes Peninsula, King George Island. Old marine deposits (ca. 30000 yrs BP) with shells, whale bones and marine algae in situ were found in the western coastal and northern inland territories at the altitudes of 20-40 m a.s.l. that evidences the covering of considerable part of the peninsula by relatively warm sea waters before the Last Glacial Maximum. Quite good preservation of these deposits supposes relatively small thickness and weak erosional potential of ice masses overlying the area during the LGM. The early Holocene phase of the peninsula deglaciation was caused by both climate warming and marine transgression, which left the deposits with fossil flora and fauna at heights up to 15 m a.s.l. (maximum rise of the relative sea-level 7000-8000 yrs BP). During the middle Holocene, glacier contraction in the area continued (on the whole) due to mainly favorable climatic conditions. The presence of marine and terrestrial deposit blocks (with shells, algae, mosses) in moraine ridges on the surface of Collins Ice Cap signifies that this glacier could vanish from the peninsula during climate optimum (ca. 4000-3000 yrs BP). The processes of new formation and growth of the ice cap started probably ca. 2000 yrs BP; within the last 1000 years the limited advance of the glacier occurred (likely corresponding to the Little Ice Age), and was replaced then by modern process of its decay.

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. Late Pleistocene-Holocene Climate Change Inferred from Fossil Fauna in the Marmara Sea, Turkey

    NASA Astrophysics Data System (ADS)

    Gurung, D.; McHugh, C. M.; Ryan, W. B.; Giosan, L.; Mart, Y.; Cagatau, N.

    2006-12-01

    Paleoenvironmental changes that document the reconnection of the Marmara Sea to the world's oceans were investigated from sediment cores and high-resolution CHIRP subbottom profiles acquired by the R/V Mediterranean Explorer in 2005. The transition from a glacial fresh/brackish water lake to a sea took place after global sea-level reached the Dardanelles outlet sill depth of -85m. We surveyed the continental shelf-slope boundary along the northern margin at Cekmece and the eastern margin at the Prince Islands in water depths extending from 80 to 135 m. Mollusk, ostracod, and foraminiferal faunal assemblages calibrated to radiocarbon chronology and sediment analyses reveal the mixing of marine and lake sediments, and very high sedimentation rates, 50 cm per 1000 years, from ~12 to 10.5 cal ka BP. Very high sedimentation rates (70 cm/1000 years) and an abrupt transition from lake stage to marine were documented along the southern shelf at Imrali from ~12.5 to 11.5 cal ka BP. This older age was derived from foraminifers. Marine mollusks Corbula sp., Lucinella sp., and Gouldia sp. are found in sand beds contained within stiff clays. The sands are rich in spherical, calcium carbonate, oolites commonly associated with shallow environments, agitated waters, and warm evaporative climates. The stiff clays contain low salinity 1-5 per mil bivalve Dreissena rostriformis, gastropod, Theodoxus fluviatilis, and fresh brackish ostracods and are interpreted as lake sediments. Paleoshorelines along the northern, eastern, and southern shelves were below the Dardanelles outlet sill of -85m at the time of marine reconnection. The drawdown of Marmara Lake prior to marine intrusion is also consistent with regional aridity. After 10.5 cal ka BP sediments and faunal assemblages are fully marine with mollusks (Corbula sp., Lucinella sp., Turritela sp., and Gouldia sp) and ostracods. Even though benthic foraminifers are rich after the marine conditions were established, planktonic

  14. 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…

  15. 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…

  16. 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

  17. 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

  18. Global environmental change: Its nature and impact

    SciTech Connect

    Hidore, J.J.

    1996-12-31

    This book is intended as an entry-level textbook on environmental science for nonscience majors. Twenty chapters address topics from historical geology and climatic change to population dynamics, land-use, water pollution, ozone depletion and biodiversity, global warming.

  19. 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. Published by Elsevier Ltd.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. Forest declines in response to environmental change

    Treesearch

    Philip M. Wargo; Allan N.D. Auclair

    2000-01-01

    Decline diseases are intimately linked to stress and environmental change. There is strong evidence that, as a category, decline diseases have increased significantly in response to the climate, air chemistry, and other changes documented in the northeastern United States over the past century, and particularly the last two decades. No other forest response to...

  8. Monitoring adaptive genetic responses to environmental change

    Treesearch

    Michael M. Hansen; Isabelle Olivieri; Donald M. Waller; Einar E. Nielsen; F. W. Allendorf; M. K. Schwartz; C. S. Baker; D. P. Gregovich; J. A. Jackson; K. C. Kendall; L. Laikre; K. McKelvey; M. C. Neel; N. Ryman; R. Short Bull; J. B. Stetz; D. A. Tallmon; C. D. Vojta; R. S. Waples

    2012-01-01

    Widespread environmental changes including climate change, selective harvesting and landscape alterations now greatly affect selection regimes for most organisms. How animals and plants can adapt to these altered environments via contemporary evolution is thus of strong interest. We discuss how to use genetic monitoring to study adaptive responses via repeated analysis...

  9. Pleistocene climate changes shaped the population structure of Partamona seridoensis (Apidae, Meliponini), an endemic stingless bee from the Neotropical dry forest.

    PubMed

    Miranda, Elder Assis; Ferreira, Kátia Maria; Carvalho, Airton Torres; Martins, Celso Feitosa; Fernandes, Carlo Rivero; Del Lama, Marco Antonio

    2017-01-01

    Partamona seridoensis is an endemic stingless bee from the Caatinga, a Neotropical dry forest in northeastern Brazil. Like other stingless bees, this species plays an important ecological role as a pollinator. The aim of the present study was to investigate the genetic structure and evolutionary history of P. seridoensis across its current geographic range. Workers from 84 nests from 17 localities were analyzed for COI and Cytb genic regions. The population structure tests (Bayesian phylogenetic inference, AMOVA and haplotype network) consistently characterized two haplogroups (northwestern and eastern), with little gene flow between them, generating a high differentiation between them as well as among the populations within each haplogroup. The Mantel test revealed no isolation by distance. No evidence of a potential geographic barrier in the present that could explain the diversification between the P. seridoensis haplogroups was found. However, Pleistocene climatic changes may explain this differentiation, since the initial time for the P. seridoensis lineages diversification took place during the mid-Pleistocene, specifically the interglacial period, when the biota is presumed to have been more associated with dry conditions and had more restricted, fragmented geographical distribution. This event may have driven diversification by isolating the two haplogroups. Otherwise, the climatic changes in the late Pleistocene must not have drastically affected the population dynamics of P. seridoensis, since the Bayesian Skyline Plot did not reveal any substantial fluctuation in effective population size in either haplogroup. Considering its importance and the fact that it is an endemic bee from a very threatened Neotropical dry forest, the results herein could be useful to the development of conservation strategies for P. seridoensis.

  10. Pleistocene climate changes shaped the population structure of Partamona seridoensis (Apidae, Meliponini), an endemic stingless bee from the Neotropical dry forest

    PubMed Central

    Ferreira, Kátia Maria; Carvalho, Airton Torres; Martins, Celso Feitosa; Fernandes, Carlo Rivero; Del Lama, Marco Antonio

    2017-01-01

    Partamona seridoensis is an endemic stingless bee from the Caatinga, a Neotropical dry forest in northeastern Brazil. Like other stingless bees, this species plays an important ecological role as a pollinator. The aim of the present study was to investigate the genetic structure and evolutionary history of P. seridoensis across its current geographic range. Workers from 84 nests from 17 localities were analyzed for COI and Cytb genic regions. The population structure tests (Bayesian phylogenetic inference, AMOVA and haplotype network) consistently characterized two haplogroups (northwestern and eastern), with little gene flow between them, generating a high differentiation between them as well as among the populations within each haplogroup. The Mantel test revealed no isolation by distance. No evidence of a potential geographic barrier in the present that could explain the diversification between the P. seridoensis haplogroups was found. However, Pleistocene climatic changes may explain this differentiation, since the initial time for the P. seridoensis lineages diversification took place during the mid-Pleistocene, specifically the interglacial period, when the biota is presumed to have been more associated with dry conditions and had more restricted, fragmented geographical distribution. This event may have driven diversification by isolating the two haplogroups. Otherwise, the climatic changes in the late Pleistocene must not have drastically affected the population dynamics of P. seridoensis, since the Bayesian Skyline Plot did not reveal any substantial fluctuation in effective population size in either haplogroup. Considering its importance and the fact that it is an endemic bee from a very threatened Neotropical dry forest, the results herein could be useful to the development of conservation strategies for P. seridoensis. PMID:28410408

  11. 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.

  12. 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

  13. 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.

  14. [Subjective causal scenarios for global environmental change].

    PubMed

    Böhm, G; Mader, S

    1998-01-01

    Two studies are presented that investigate the assumptions that risk evaluation is based on subjective causal scenarios, and that the cognitive representation of global environmental risks is structured according to five causal levels: human attitudes, human activities, emissions or pollutions, environmental changes, and negative consequences. In study 1, 30 subjects listed in free-response format causes, consequences, and remedial measures for 14 environmental risks. Differences between predictive and diagnostic inferences were found: whereas subjects tend to assign immediate rather than mediated causes, they predominantly assign negative consequences for humans, irrespective of the length of the causal chain that leads to these consequences. In study 2, 41 subjects judged the overall similarity between 25 environmental risks. A multidimensional scaling analysis of these similarity judgments replicates the theoretically assumed five causal levels. Results of both studies support the assumptions that risk evaluation is based on implicit causal hypotheses and that the proposed five-level structure adequately describes the cognitive representation of environmental risks.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. Evolutionary history of a widespread Indo-Pacific goby: the role of Pleistocene sea-level changes on demographic contraction/expansion dynamics.

    PubMed

    Hoareau, Thierry Bernard; Boissin, Emilie; Berrebi, Patrick

    2012-01-01

    Compared to endemics, widespread species are of particular interest to retrace recent evolutionary history. These species have a large population size which provides a clearer genetic signature of past events. Moreover, their wide geographic range increases the potential occurrence of evolutionary events (expansion, divergence, etc.). Here, we used several coalescent-based methods to disentangle the evolutionary history of a widespread amphidromous goby (Sicyopterus lagocephalus), in the light of sea-level variations during the Pleistocene. Using 75 samples recovered from three biogeographic regions (Western Indian Ocean, Melanesia and Polynesia), we analysed a portion of the cytochromeb gene and confirmed three major haplogroups, each specific to a region. Furthermore, we found that: (1) the Melanesian haplogroup was the oldest while the two peripheral regions hosted daughter haplogroups; (2) two centrifugal colonisation events occurred from Melanesia to the periphery, each synchronised with periods of strong paleo-ENSO episodes; (3) the demographic contraction-expansion events were linked to Pleistocene sea-level changes; (4) Melanesia and Polynesia acted as efficient refuges during the Last Glacial Maximum. These results highlight the importance of studying widespread species to better understand the role of climate changes and paleo-oceanography on the evolution of biodiversity. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. 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.

  2. 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.

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

    PubMed Central

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

    2012-01-01

    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. PMID:23185018

  4. 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.

  5. 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

  6. Palaeoenvironmental changes in the Marmara region (Turkey) during late Pleistocene and Holocene. Implication for Neo- and Palaeolithic communities.

    NASA Astrophysics Data System (ADS)

    Viehberg, F. A.; Damcı, E.; Ülgen, U. B.; Roeser, P.; Franz, S. O.; Çaǧatay, N.; Litt, T.; Melles, M.

    2012-04-01

    The Marmara region is a geographical bottleneck for the transcontinental dispersal of modern humans from the Near East to the Balkans. Thus, climate and environmental reconstructions of this key area are of uttermost importance to test hypotheses postulating migration periods influenced directly or indirectly by external forces. Lake Iznik is located in the study area and holds a continuous sediment archive sensitive to climate and environmental changes. We recovered sediment cores of max 39.0 cal kyr (17 m sediment depth) enabling us to reconstruct the environmental history and climate patterns on local and regional scale during the reestablishment of human habitats after the Last glacial maximum and the dispersal of Neolithic economy (15,000-7,000 a BP). Geomorphological findings in the lake basin and geochemical analyses hint to prevailing east or west winds at least since 36 cal. kyr BP and lasted until c. 11 cal. kyr BP. This supports the theory of a climate pattern decoupled from North Atlanic oscillations. The scarce palaeolithic findings in the surrounding area were evaluated under this aspect to gain new information of human migration in the eastern Mediterranean.

  7. Methods for environmental change; an exploratory study

    PubMed Central

    2012-01-01

    Background While the interest of health promotion researchers in change methods directed at the target population has a long tradition, interest in change methods directed at the environment is still developing. In this survey, the focus is on methods for environmental change; especially about how these are composed of methods for individual change (‘Bundling’) and how within one environmental level, organizations, methods differ when directed at the management (‘At’) or applied by the management (‘From’). Methods The first part of this online survey dealt with examining the ‘bundling’ of individual level methods to methods at the environmental level. The question asked was to what extent the use of an environmental level method would involve the use of certain individual level methods. In the second part of the survey the question was whether there are differences between applying methods directed ‘at’ an organization (for instance, by a health promoter) versus ‘from’ within an organization itself. All of the 20 respondents are experts in the field of health promotion. Results Methods at the individual level are frequently bundled together as part of a method at a higher ecological level. A number of individual level methods are popular as part of most of the environmental level methods, while others are not chosen very often. Interventions directed at environmental agents often have a strong focus on the motivational part of behavior change. There are different approaches targeting a level or being targeted from a level. The health promoter will use combinations of motivation and facilitation. The manager will use individual level change methods focusing on self-efficacy and skills. Respondents think that any method may be used under the right circumstances, although few endorsed coercive methods. Conclusions Taxonomies of theoretical change methods for environmental change should include combinations of individual level methods that may

  8. Forecasting agriculturally driven global environmental change.

    PubMed

    Tilman, D; Fargione, J; Wolff, B; D'Antonio, C; Dobson, A; Howarth, R; Schindler, D; Schlesinger, W H; Simberloff, D; Swackhamer, D

    2001-04-13

    During the next 50 years, which is likely to be the final period of rapid agricultural expansion, demand for food by a wealthier and 50% larger global population will be a major driver of global environmental change. Should past dependences of the global environmental impacts of agriculture on human population and consumption continue, 10(9) hectares of natural ecosystems would be converted to agriculture by 2050. This would be accompanied by 2.4- to 2.7-fold increases in nitrogen- and phosphorus-driven eutrophication of terrestrial, freshwater, and near-shore marine ecosystems, and comparable increases in pesticide use. This eutrophication and habitat destruction would cause unprecedented ecosystem simplification, loss of ecosystem services, and species extinctions. Significant scientific advances and regulatory, technological, and policy changes are needed to control the environmental impacts of agricultural expansion.

  9. Monitoring environmental change with color slides

    Treesearch

    Arthur W. Magill

    1989-01-01

    Monitoring human impact on outdoor recreation sites and view landscapes is necessary to evaluate influences which may require corrective action and to determine if management is achieving desired goals. An inexpensive method to monitor environmental change is to establish camera points and use repeat color slides. Successful monitoring from slides requires the observer...

  10. Late Pleistocene climate change promoted divergence between Picea asperata and P. crassifolia on the Qinghai-Tibet Plateau through recent bottlenecks.

    PubMed

    Bi, Hao; Yue, Wei; Wang, Xi; Zou, Jiabin; Li, Lili; Liu, Jianquan; Sun, Yongshuai

    2016-07-01

    Divergence during the early stage of speciation can be driven by a population bottleneck via reduced gene flow and enhanced lineage sorting. In this study, we aimed to examine whether such bottlenecks occurred during the initial speciation of two closely related spruce species Picea asperata and P. crassifolia occurring on the Qinghai-Tibet Plateau (QTP). We analyzed sequences of three chloroplast, two mitochondrial DNA fragments and a further 13 nuclear loci from 216 individuals of the two species. Both species showed a low level of genetic diversity in contrast to other congeners occurring in the QTP and adjacent regions. The estimated population sizes of P. asperata and P. crassifolia are less than the ancestral population size before splitting. These results together with multiple statistical tests (Tajima's D, Fu and Li's D* and F*) suggest that these two species underwent recent bottlenecks. Based on approximate Bayesian computation (ABC), we also determined that the period of the population shrinkage was consistent with the interspecific divergence during the late Pleistocene. The reduced population sizes and the divergent selection may together have triggered the initial divergence under high gene flow between these two species. Our results therefore highlight the importance of climatic oscillations during the late Pleistocene in promoting speciation through changing demographic sizes of the ancestral species on the QTP and in adjacent regions.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Global Environmental Change: Modelling and Monitoring

    NASA Astrophysics Data System (ADS)

    Kelley, John J.

    The second half of the 20th century was a period of unprecedented and rapid change in the global population, the biosphere, the world economy and society. Recent inquiry related to the environmental effects has focused on the complexities of how the Earth behaves as a system, with connectivity linking its oceans, land, atmosphere, living, and non-living components. The search for delineation of natural and human causes and effects of global change has ushered in new mathematical approaches to the pursuit of a global environmental system science. Judging from the reports of several international conferences—for example, The Amsterdam Declaration on Global Change, 2000—a consistent theme has emerged, calling for the development of an effective ethical framework of global stewardship and strategies (modeling and monitoring) for Earth system management.

  16. 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

  17. 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.

  18. Integrated palaeoenvironmental reconstruction of a Lower Pleistocene section (Sousaki basin, Northeastern Corinth Gulf): using fuzzy logic to decipher long term palaeoenvironmental changes.

    NASA Astrophysics Data System (ADS)

    Papadopoulou, Pinelopi; Iliopoulos, George; Koukouvelas, Ioannis; Rentoumi, Evaggelia; Groumpos, Peter

    2017-04-01

    Palaeoecological analyses are important tools for the reconstruction of palaeoenvironmental changes. In this paper microfossil assemblages (ostracodes and palynomorphs) of Lower Pleistocene age, are used to reconstruct the biological and physical conditions of the palaeoenvironment during a time interval when palaeoclimatic and palaeoecological data from the Balkan Peninsula are scarce. Lower Pleistocene is an epoch when major changes in the palaeoclimate occurred (commencement of the Quaternary glaciations) affecting the palaeoenvironments worldwide. The studied section, geotectonically belongs to the Northeastern Corinth gulf, and lies near the town Ag. Theodoroi, west of Athens, consisting of alterations of marls and marly limestones with intercalations of organic rich sediments and gypsum beds. Detailed logging of the section was carried out and 76 samples were collected for micropalaeontological analysis. Additionally, 22 samples were studied for their palynological content. The results were statistically processed using standard palaeoecological methods (percentage abundance diagrams, biodiversity indices and multivariate analysis). Our interpretation was further supported by fuzzy logic methods, in order to remove subjectivity from the biostratigraphical data providing a higher degree of detail. Despite this though, their use in geology remains limited until now. In our case study, fuzzy sets examine the data from a more general perspective and contain natural variations that are present in species abundance gradients between evolving environments. The lithological and micropalaeontological analysis revealed a brackish lagoonal environment dominated by the typical brackish ostracode species Cyprideis torosa. The studied sequence shows cyclically changing subenvironments fluctuating from the outer to the inner zone of a lagoon as imposed by the alternating occurrence of the ostracode families Tyrrhenocytheridae and Candonidae and the foraminifera species A

  19. 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.

  20. 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.

  1. Novelty detection under changing environmental conditions

    NASA Astrophysics Data System (ADS)

    Sohn, Hoon; Worden, Keith; Farrar, Charles R.

    2001-07-01

    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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

    Pyenson, Nicholas D; Lindberg, David R

    2011-01-01

    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. 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. 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 by employing generalist filter-feeding modes, similar to the

  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. 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.

  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. 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.

  12. 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

  13. Environmental change, phenotypic plasticity, and genetic compensation.

    PubMed

    Grether, Gregory F

    2005-10-01

    When a species encounters novel environmental conditions, some phenotypic characters may develop differently than in the ancestral environment. Most environmental perturbations of development are likely to reduce fitness, and thus selection would usually be expected to favor genetic changes that restore the ancestral phenotype. I propose the term "genetic compensation" to refer to this form of adaptive evolution. Genetic compensation is a subset of genetic accommodation and the reverse of genetic assimilation. When genetic compensation has occurred along a spatial environmental gradient, the mean trait values of populations in different environments may be more similar in the field than when representatives of the same populations are raised in a common environment (i.e., countergradient variation). If compensation is complete, genetic divergence between populations may be cryptic, that is, not detectable in the field. Here I apply the concept of genetic compensation to three examples involving carotenoid-based sexual coloration and then use these and other examples to discuss the concept in a broader context. I show that genetic compensation may lead to a cryptic form of reproductive isolation between populations evolving in different environments, may explain some puzzling cases in which heritable traits exposed to strong directional selection fail to show the expected evolutionary response, and may complicate efforts to monitor populations for signs of environmental deterioration.

  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. 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.

  16. (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.

  17. 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

  18. 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.

  19. 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.

  20. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Global environmental change research: empowering developing countries.

    PubMed

    Nobre, Carlos A; Lahsen, Myanna; Ometto, Jean P H B

    2008-09-01

    This paper discusses ways to reconcile the United Nations Millennium Development Goals with environmental sustainability at the national and international levels. The authors argue that development and better use of sustainability relevant knowledge is key, and that this requires capacity building globally, and especially in the less developed regions of the world. Also essential is stronger integration of high-quality knowledge creation and technology--and policy--development, including, importantly, the creation of centers of excellence in developing regions which effectively use and produce applications-directed high quality research and bring it to bear on decision making and practices related to environmental change and sustainable management of natural resources. The authors argue that Southern centers of excellence are a necessary first step for bottom-up societal transformation towards sustainability, and that such centers must help design innovative ways to assess and place value on ecosystem services.

  2. 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. © 2015 John Wiley & Sons Ltd.

  3. Analysis of vegetation and climate change during Late Pleistocene from Ziro Valley, Arunachal Pradesh, Eastern Himalaya region

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Amalava; Mehrotra, Nivedita; Shah, Santosh K.; Basavaiah, Nathani; Chaudhary, Vandana; Singh, Indra Bir

    2014-10-01

    Vegetation and climate during later part of Late Pleistocene have been reconstructed from Ziro valley, Arunachal Pradesh, Eastern Himalaya based on pollen data along with carbon isotope and magnetic susceptibility data The study reveals that the area and the vicinity is occupied by mixed broad leaved - conifer forest and pine grass savanah at variable densities at least since 66,000yr BP. The phases of expansions and declines of Oaks with decline and increase of Pines and grasses probably occurred under increase (warm-moist) and decrease (cool-dry) of S.W. monsoon precipitation respectively. The increasing trend of S.W. monsoon and temperature is recorded during ˜44,000 to 34,000 cal yr BP synchronizing with the peat development, and which peaked at around 35,000 cal yr BP. This may link to the interstadial phase during the last major glacial cycle in the Himalayan region. It is also reflected in the decline of δ13C value indicating dominance of C-3 type of vegetation. The increased values of χFD%, and lower values χLF magnetic susceptibility, recorded during the phase of the peat deposit, further advocate's higher monsoon intensity. Impact of expansion of glacier felt with peak (LGM) around 20,000 cal yr BP is perceived. Tree line had moved to lower altitudes due to increased aridity and low temperature. During this time existence of savannah type of vegetation is also evident by the increase of C4 taxa. Decreased FD% and increased χLF susceptibility also indicate reduced S.W. monsoon intensity.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. Consideration of environmental change in performance assessments.

    PubMed

    Pinedo, P; Thorne, M; Egan, M; Calvez, M; Kautsky, U

    2005-01-01

    Depending on the particular circumstances in which a post-closure performance assessment of a radioactive waste repository is made, it may be appropriate to follow simple or more complex approaches in characterising the biosphere. Several different Example Reference Biospheres were explored in BIOMASS Theme 1 to address a range of issues that arise. Here, consideration is given to Example Reference Biospheres relevant to representing the implications of changes that may occur within the biosphere system during the period over which releases of radionuclides from a disposal facility might take place. Mechanisms of change considered include those extrinsic and intrinsic to the system of interest. An overall methodology for incorporating environmental change into assessments is proposed. This includes screening of primary mechanisms of change; identification of possible time sequences of change; development of a coherent description of the regional landscape response for each time sequence; integration of source term and geosphere-biosphere interface information; identification and description of one or more time series of assessment biospheres; and evaluation of the advantages and disadvantages of simulating the effects of sequences of biosphere systems and the transitions between them, or of defining a set of biosphere systems to be represented individually in a non-sequential analysis. The usefulness of the methodology is explored in two site-specific examples and one generic example.

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

    PubMed

    Terry, Rebecca C; Rowe, Rebecca J

    2015-08-04

    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.

  10. 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

  11. 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

  12. Late Pleistocene and early Holocene change in the Weddell Sea: a new climate record from the Patriot Hills, Ellsworth Mountains, West Antarctica

    NASA Astrophysics Data System (ADS)

    Turney, C. S.; Fogwill, C. J.; Rubino, M.; Etheridge, D. M.; van Ommen, T. D.; Moy, A. D.; Curran, M. A.

    2014-12-01

    The transition from the late Pleistocene to the Holocene (30 000-5000 years ago) was a period of considerable climate variability, which has been associated with changes in deep water formation and the intensity of the Meridional Overturning Circulation. Although numerous records exist across the North Atlantic region, few Antarctic ice core records have been obtained from the south. Here we exploit the potential of upwelling ancient ice - so-called blue ice areas (BIAs) - from the Patriot Hills in the Ellsworth Mountains to derive the first deuterium isotope record (dD) from continental Antarctica south of the Weddell Sea. Gas analysis and glaciological considerations provide a first relative chronology and provide new constraints on ice sheet dynamics in the region. Inferred temperature trends from the Patriot Hills BIA and snow pit suggest changing climate influences during the transition between the last glacial period and Holocene. Our results demonstrate the considerable potential of the Patriot Hills site for reconstructing past climate change in the south Atlantic region.

  13. 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)

  14. Evolution of Chaka Salt Lake in NW China in response to climatic change during the Latest Pleistocene Holocene

    NASA Astrophysics Data System (ADS)

    Xingqi, Liu; Dong, Hailiang; Rech, Jason A.; Matsumoto, Ryo; Bo, Yang; Yongbo, Wang

    2008-04-01

    The Late Pleistocene and Holocene hydrologic balance of Chaka Salt Lake in the eastern Qaidam Basin of NW China was studied based on the analysis of lithostratigraphy, mineralogy, total organic carbon, and total nitrogen from a 9.0-m long sediment core. An age-depth model for the lake sediments is based on eight accelerator mass spectrometry (AMS) 14C measurements of organic matter and a 1700-year radiocarbon reservoir correction. The Pitzer model was used to calculate the sequence of minerals precipitated as a function of salinity assuming that the initial lake water was recharged from adjacent rivers and springs. Lake salinity values were derived from a good match between the calculated and observed mineral sequences. Our multi-proxy based hydrologic reconstruction of Chaka Lake indicates that it was a clastic-dominated, freshwater lake between 17.2 and 11.4 cal ka BP, which may have resulted from the input of glacial water into the lake at that time. During the Lateglacial and Holocene, a warm climatic regime predominated between 13.9 and 12.7 cal ka BP and then a cold climatic regime prevailed between 12.7 and 11.4 cal ka BP. These warm and cold periods correlate with the Bølling-Allerød and Younger Dryas events in the region. Beginning at 11.4 cal ka BP, a saline or hypersaline lake developed, which may have resulted from increased summer insolation and temperatures. These conditions persisted throughout the Holocene. Modeling indicates that lake salinity fluctuated between 66 and 223 ppt from 11.4 to 7.2 cal ka BP and then increased to 223-322 ppt between 7.2 and 6.0 cal ka BP, when most regions of China recorded high moisture availability (i.e. the so-called "mid-Holocene Climatic Optimum"). Lake salinity decreased to 66-223 ppt during a short time period between 6.0 and 5.3 cal ka BP, possibly caused by reduced evaporation. Subsequently, salinity values rapidly increased to 223-322 ppt between 5.3 and 5.2 cal ka BP and a hypersaline lake with a salinity

  15. 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

  16. 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

  17. Trace element evidence for abrupt changes in deep South Atlantic Ocean nutrient and carbonate chemistry across the Mid-Pleistocene Transition

    NASA Astrophysics Data System (ADS)

    Farmer, J. R.; Hoenisch, B.; Haynes, L.; Kroon, D.; Bell, D. B.; Jung, S.; Seguí, M. J.; Raymo, M. E.; Goldstein, S. L.; Pena, L. D.

    2016-12-01

    Pleistocene glaciations underwent a profound transition from lower amplitude 40 kyr cycles to high amplitude 100 kyr cycles between 1.2 and 0.8 Ma, an interval termed the Mid-Pleistocene Transition (MPT). While the underlying causes of the MPT are uncertain, previous studies show quasi-contemporaneous reductions in North Atlantic Deep Water (NADW) export1 and glacial atmospheric pCO22 around 0.9 Ma. Although this suggests a possible role for enhanced deep-ocean carbon storage in amplifying climate change across the MPT, few direct records of deep ocean carbonate chemistry exist for this interval to test this hypothesis. Here we present South Atlantic benthic foraminiferal B/Ca and Cd/Ca records from International Ocean Discovery Program Sites 1088, 1264 and 1267 (2.1 to 4.3 km water depth) as part of a larger study of Atlantic-wide changes in deep ocean chemistry and circulation spanning the MPT. Results show an abrupt 15-20% decrease in benthic B/Ca and 40-50% increase in Cd/Ca at 4.3 km depth (Site 1267) between 1.0 and 0.9 Ma. Site 1088, which at 2.1 km depth is sensitive to input of southern-sourced Upper Circumpolar Deep Water, shows a prolonged 25% decrease in B/Ca and 50% increase in Cd/Ca from 1.0 to 0.6 Ma. In contrast, at Site 1264 ( 2.5 km depth within the core of modern NADW) B/Ca and Cd/Ca changes across the MPT are more modest (-5% and +10%, respectively). These observations reflect on the accumulation of regenerated carbon and nutrients in the deep South Atlantic, and varying contributions of northern- and southern-sourced watermasses to each core site. Implications for deep-ocean carbon storage and forcing of the MPT will be discussed. 1Pena, L. and Goldstein, S. (2014), Science 345, 318 2Hönisch, B. et al. (2009), Science 324, 1551

  18. Marine ostracod turnover tracks orbitally forced palaeoenvironmental changes at the Lower-Middle Pleistocene transition: the case study of the Valle di Manche section (Calabria, southern Italy)

    NASA Astrophysics Data System (ADS)

    Rossi, Veronica; Scarponi, Daniele; Capraro, Luca; Ferretti, Patrizia; Macrì, Patrizia

    2017-04-01

    Ostracods, small crustaceans living in almost every aquatic depositional setting, are widely used in palaeoenvironmental reconstructions due to their well-known ecological sensitivity. A close connection between the composition of ostracod fauna and the Milankovitch climate-eustatic variability has been documented in several Plio-Pleistocene marine sections of the Central Mediterranean area. The Valle di Manche section (VdM; Calabria, southern Italy), one of the suitable candidates to host the Global Stratotype Section and Point (GSSP) of the Ionian Stage-Middle Pleistocene, represents an ideal venue where to investigate ostracod turnover in relation to orbitally forced palaeoenvironmental changes, being firmly constrained in time and well documented by a number of independent climatic proxy. A high-resolution, quantitative analysis of the ostracod fauna has been undertaken on the middle part of the VdM, ca. 30 m-thick and showing two T-R cycles developed at the Lower-Middle Pleistocene transition (late MIS 21 to early MIS 18). Within each cycle, a relatively thin, fining-upward transgressive muddy unit is overlain by gradually coarsening upward and more expanded regressive silty to sand packages. A total of 40 samples have been selected to characterise the whole spectrum of lithofacies and detect high-frequency palaeoenvironmental variations especially within homogeneous clayey stratigraphic intervals. Taxa typical of circalittoral (>70/100 m) depths (e.g., Bosquetina dentata, Cytherella vulgatella, Cytheropteron monoceros, Pterygocythereis ceratoptera and Krithe species), commonly accompanied by the lower circalittoral-bathyal species Henryhowella sarsii, occur within the fine-grained units developed during the full interglacials of MIS 21 and MIS 19. Furthermore, ostracod assemblages document that the oxygen availability at the sea floor changed during MIS 19. In contrast, a less-diversified ostracod fauna dominated by Aurila convexa, a species preferring

  19. 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.

  20. Megafaunal isotopes reveal role of increased moisture on rangeland during late Pleistocene extinctions.

    PubMed

    Rabanus-Wallace, M Timothy; Wooller, Matthew J; Zazula, Grant D; Shute, Elen; Jahren, A Hope; Kosintsev, Pavel; Burns, James A; Breen, James; Llamas, Bastien; Cooper, Alan

    2017-04-18

    The role of environmental change in the late Pleistocene megafaunal extinctions remains a key question, owing in part to uncertainty about landscape changes at continental scales. We investigated the influence of environmental changes on megaherbivores using bone collagen nitrogen isotopes (n = 684, 63 new) as a proxy for moisture levels in the rangelands that sustained late Pleistocene grazers. An increase in landscape moisture in Europe, Siberia and the Americas during the Last Glacial-Interglacial Transition (LGIT; ~25-10 kyr bp) directly affected megaherbivore ecology on four continents, and was associated with a key period of population decline and extinction. In all regions, the period of greatest moisture coincided with regional deglaciation and preceded the widespread formation of wetland environments. Moisture-driven environmental changes appear to have played an important part in the late Quaternary megafaunal extinctions through alteration of environments such as rangelands, which supported a large biomass of specialist grazers. On a continental scale, LGIT moisture changes manifested differently according to regional climate and geography, and the stable presence of grasslands surrounding the central forested belt of Africa during this period helps to explain why proportionally fewer African megafauna became extinct during the late Pleistocene.

  1. 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).

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. Global environmental change: Modifying human contributions through education

    SciTech Connect

    Carter, L.M.

    1997-12-31

    The 1995 Intergovernmental Panel on Climate Change (IPCC) Science report concludes that evidence now available {open_quotes}points toward a discernible human influence on global climate{close_quotes}. Reductions in emissions will require changes in human behavior. Knowledge, often through education, is an important moderator of human environmental behavior. This study assessed whether gains in global environmental change knowledge would lead to changes in human behaviors that could be deemed environmentally responsible.

  9. 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.

  10. 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

  11. Contrasting responses to Pleistocene climate changes: a case study of two sister species Allium cyathophorum and A. spicata (Amaryllidaceae) distributed in the eastern and western Qinghai-Tibet Plateau.

    PubMed

    Wang, Xinyu; Li, Yuanshuo; Liang, Qianlong; Zhang, Lei; Wang, Qian; Hu, Huan; Sun, Yongshuai

    2015-04-01

    It has been hypothesized that species occurring in the eastern and the western Qinghai-Tibet Plateau (QTP) responded differently to climate changes during the Pleistocene. Here, we test this hypothesis by phylogeographic analysis of two sister species, Allium cyathophorum and A. spicata. We sequenced two chloroplast DNA (cpDNA) fragments (accD-psaI and the rpl16 intron) of 150 individuals, and the nuclear (ITS) region of 114 individuals, from 19 populations throughout the distributional ranges of these species. The divergence between the two species was dated at 779 - 714 thousand years before the present and was likely initiated by the most major glaciation in the QTP. Analysis of chlorotype diversity showed that A. spicata, the species occurring in the western QTP, contains much lower genetic diversity (0.25) than A. cyathophorum (0.93), which is distributed in the eastern QTP. Moreover, multiple independent tests suggested that the A. spicata population had expanded recently, while no such expansion was detected in A. cyathophorum, indicating a contrasting pattern of responses to Pleistocene climate changes. These findings highlight the importance of geographical topography in determining how species responded to the climate changes that took place in the QTP during the Pleistocene.

  12. Dynamics of Pleistocene population extinctions in Beringian brown bears.

    PubMed

    Barnes, I; Matheus, P; Shapiro, B; Jensen, D; Cooper, A

    2002-03-22

    The climatic and environmental changes associated with the last glaciation (90,000 to 10,000 years before the present; 90 to 10 ka B.P.) are an important example of the effects of global climate change on biological diversity. These effects were particularly marked in Beringia (northeastern Siberia, northwestern North America, and the exposed Bering Strait) during the late Pleistocene. To investigate the evolutionary impact of these events, we studied genetic change in the brown bear, Ursus arctos, in eastern Beringia over the past 60,000 years using DNA preserved in permafrost remains. A marked degree of genetic structure is observed in populations throughout this period despite local extinctions, reinvasions, and potential interspecies competition with the short-faced bear, Arctodus simus. The major phylogeographic changes occurred 35 to 21 ka B.P., before the glacial maximum, and little change is observed after this time. Late Pleistocene histories of mammalian taxa may be more complex than those that might be inferred from the fossil record or contemporary DNA sequences alone.

  13. 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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. 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.

  15. The Mediterranean Plio-Pleistocene: A reference frame for astronomically paced low and high latitude climate changes (Jean Baptiste Lamarck Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Lourens, Lucas

    2016-04-01

    The astronomical theory of climate has revolutionized our understanding of past climate change and the development of highly accurate geologic time scales for the entire Cenozoic. Most of this understanding has started with the construction of high-resolution stable oxygen isotope (18O) records from planktonic and benthic foraminifera of open ocean deep marine sediments explored by the international drilling operations of DSDP, ODP and IODP. These efforts culminated into global ocean isotopic stacked records, which give a clear picture of the evolution of the climate state through time. Fundamental for these reconstructions are the assumptions made between the astronomical forcing and the tuned time series and the accuracy of the astronomical solution. In the past decades, an astronomically calibrated time scale for the Pliocene and Pleistocene of the Mediterranean has been developed, which has become the reference for the standard Geologic Time Scale. Characteristic of the studied marine sediments are the cyclic lithological alternations, reflecting the interference between obliquity and precession-paced low latitude climate variability. These interference patterns allowed to evaluate the accuracy of astronomical solutions and to constrain the dynamical ellipticity of the Earth and tidal dissipation by the Sun and the Moon, which in turn provided the backbone for the widely applied LR04 open ocean benthic isotope stack of the past 5 Myr. So far, the assumed time lags between orbital forcing and the global climate response as reflected in LR04 have not been tested, while these assumptions hark back to SPECMAP, using simple ice sheet models and a limited number of radiometric dates. In addition, LR04 adopted a shorter response time for the smaller ice caps during the Pliocene. Here I present the first benthic 18O record of the Mediterranean reference scale, which strikingly mirrors the LR04. I will use this record to discuss the assumed phase relations and its

  16. 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.

  17. Forest environmental investments and implications for climate change mitigation.

    Treesearch

    Ralph J. Alig; Lucas S. Bair

    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...

  18. 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

  19. 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. © 2015 John Wiley & Sons Ltd/CNRS.

  20. Fluvial response to sea-level changes since the latest Pleistocene in the near-coastal lowland, central Kanto Plain, Japan

    NASA Astrophysics Data System (ADS)

    Ishihara, Takeshi; Sugai, Toshihiko; Hachinohe, Shoichi

    2012-04-01

    This paper addresses the influence of sea level changes on the stratigraphy and basal topography of latest Pleistocene-Holocene incised valley fill of the Arakawa and Menuma Lowlands in central Japan by using sedimentary drill cores and columnar geologic sections. In the study area, four buried fluvial terrace surfaces (I to IV) formed in response to sea-level fall during the last glacial period. Surface III is covered with As-YP tephra (15-16.5 ka) and extends at least 65 km landward from the present mouth of the Arakawa River. A buried valley named surface V that extends from at least 85 km upstream from the present river mouth to about 120 m below present sea level on the continental slope was incised in response to the sea-level lowstand of the Last Glacial Maximum. The incised valley fill can be divided into three units: unit A (gravelly river channel sediments including valley-bottom gravels), unit B (fluvial sediments), and unit C (marine sediments), which intertongues within unit B and pinches out up to 60 km upstream from the present river mouth. Unit C marks the landward limit of Holocene transgression. The lower part of unit B is a fining-upward succession formed during rising sea level and indicates retrogressive aggradation of floodplain sediments during transgression, whereas the upper part of unit B was formed during a sea-level highstand. The floodplain migrated more than 85 km upstream from the modern shoreline in response to sea-level rise until the middle Holocene and extends over several tens of kilometers beyond the landward limit of the Holocene marine transgression.

  1. 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.

  2. 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.

  3. Late Pleistocene spread of (cool-)temperate forests in Northeast China and climate changes synchronous with the North Atlantic region

    NASA Astrophysics Data System (ADS)

    Stebich, Martina; Mingram, Jens; Han, Jingtai; Liu, Jiaqi

    2009-01-01

    The results presented here from the annually laminated sedimentary sequence of Sihailongwan lake provide the first comprehensive palaeoecological record covering the Late Pleniglacial to the Early Holocene (16,700-10,600 cal yrs. BP) from Northeast China. High-resolution pollen analyses have enabled the vegetational and climatic changes of the last glacial-interglacial transition to be reconstructed in more detail than has been previously possible. Moreover, a reliable chronology has been provided by both varve counting and 40 calibrated AMS 14C age determinations. Palaeobotanical evidence indicates predominantly steppe and open taiga-like woodland communities, with abundant Betula, Larix, Alnus fruticosa, Artemisia, grasses and sedges, which are typical of cold and dry conditions between 16,700 and 14,450 cal yrs. BP. The beginning expansion of Ulmus and Fraxinus marks the onset of the Late-glacial climatic amelioration at 14,450 cal yrs. BP. Dense deciduous forests, predominantly consisting of thermophilous broadleaf taxa, become established and widespread during the Early Holocene. Two short-term climatic reversals to colder and/or dryer conditions are recorded in the proxy data between 13,900 and 13,800 cal yrs. BP and 13,100 and 12,900 cal yrs. BP, correlating with the Oldest Dryas/Greenland Interstadial (GI) 1d event and the Gerzensee/Killarney/GI-1b oscillation, respectively. The prominent reappearance of Picea and Larix, coupled with a marked decrease in broadleaved trees, prior to the start of the Holocene, implies a climatic reversal compatible with the Younger Dryas event in the circum-Atlantic region. The evident synchroneity of climate changes in the North Atlantic region and East Asia supports the theory of strong atmospheric coupling between both regions.

  4. 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…

  5. 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…

  6. 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

  7. Environmental change: Federal courts and the EPA

    SciTech Connect

    O'Leary, R.

    1993-01-01

    This book presents the findings of a four-year study of the impact of federal court decisions on the policies and administration of the US Environmental Protection Agency (EPA) in all seven of its major statutory areas: clean air, clean water, hazardous waste cleanup, controlled pesticide use, resource conservation and recovery, safe drinking water, and control of toxic substances. The author use the Lexis and Westlaw legal data bases to generate a list of all cases in which the EPA was either a plaintiff or a defendant in each of the agency's seven major statutory areas. The author verified these data and at times supplemented them with EPA records and with environmental reporters published by the Bureau of National Affairs and the Environmental Law Institute. She derived settlement agreements from the EPA, the Department of Justice, and the courts.

  8. 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.

  9. 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.…

  10. Continental diatoms as indicators of long-term environmental change

    USGS Publications Warehouse

    Bradbury, J. Platt

    1999-01-01

    It is curious that diatoms, whose short lifespans and capacity for rapid regeneration make them especially suitable for short-term paleoenvironmental studies, would also have a significant role as indicators of long-term environmental change. This chapter explores the nature of long diatom records, their relation to global environmental changes, guidelines for their interpretation, and problems common to such records.

  11. 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…

  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. 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

  14. 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

  15. 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.

  16. Microbial Habitability and Pleistocene Aridification of the Asian Interior.

    PubMed

    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. Halite fluid inclusions-Ancient microbes-Water activity-Qaidam Basin-Pleistocene aridification. Astrobiology 16, 379-388.

  17. 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.

  18. Environmental change and Antarctic seabird populations.

    PubMed

    Croxall, J P; Trathan, P N; Murphy, E J

    2002-08-30

    Recent changes in Antarctic seabird populations may reflect direct and indirect responses to regional climate change. The best long-term data for high-latitude Antarctic seabirds (Adélie and Emperor penguins and snow petrels) indicate that winter sea-ice has a profound influence. However, some effects are inconsistent between species and areas, some in opposite directions at different stages of breeding and life cycles, and others remain paradoxical. The combination of recent harvest driven changes and those caused by global warming may produce rapid shifts rather than gradual changes.

  19. 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.

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

    PubMed Central

    Blome, Margaret W.; King, John W.; McGlue, Michael M.; Cole, Julia E.

    2016-01-01

    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. PMID:27698127

  1. 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

  2. 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

  3. 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.

  4. Middle Pleistocene interglacial Thames--Medway deposits at Clacton-on-Sea, England: Reconsideration of the biostratigraphical and environmental context of the type Clactonian Palaeolithic industry

    NASA Astrophysics Data System (ADS)

    Bridgland, David R.; Field, Michael H.; Holmes, Jonathan A.; McNabb, John; Preece, Richard C.; Selby, Ian; Wymer, John J.; Boreham, Steve; Irving, Brian G.; Parfitt, Simon A.; Stuart, Anthony J.

    In 1987 an archaeological investigation was undertaken during redevelopment of the erstwhile Butlin's holiday camp at Clacton-on-Sea, on the grounds that the Middle Pleistocene Clacton Channel Deposits, containing the type-Clactonian Palaeolithic industry, were known to extend beneath the site. Excavations for a storm-drain allowed sampling at points along a longitudinal traverse of the main Clacton Channel. Analysis of these samples has provided new palaeontological information, including data pertaining to the rise in relative sea level during the interglacial represented. Systematic studies of molluscs and ostracods, the latter undertaken at Clacton for the first time, have been particularly valuable. Information from the Butlin's site supplements evidence previously gathered from the West Cliff section and from other localities at Clacton. The calcareous clay ('marl') that underlies the Clacton golf course extends beneath Butlin's, where it was found to be part of the Freshwater Beds, not the Estuarine Beds, as hitherto supposed. The Clacton Estuarine Beds, restricted to the eastern end of the site, have their base just below 2 m O.D., implying that their superposition upon the Clacton Freshwater Beds occurred when relative sea level in this area was close to present ordnance datum. Correlation of the Clacton Channel Deposits with the interglacial immediately following the Anglian/Elsterian Stage appears secure; equivalence with Oxygen Isotope Stage 11 of the oceanic sequence is most probable. A borehole survey and subsequent excavation revealed a Holocene sequence of unlithified tufa and organic sediments beneath part of the site.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. The potential impact of global environmental change on population health.

    PubMed

    Tong, S

    2000-10-01

    Due to rapid industrial changes and increased pressure of people on fragile ecosystems, large-scale environmental perturbations have been occurring on Earth. Major current environmental problems that can be expected to have a substantial effect on human health include human-induced climate change and stratosphere ozone depletion, because they threaten the ecological support systems on which human life depends. The most serious potential consequence of global environmental change is the erosion of Earth's life-support systems. The public health assessments of the present and future anthropogenic damage to the biosphere have important implications for human health and wellbeing. Medical practitioners have an important role to play in this field.

  10. Monitoring environmental change in an ecosystem.

    PubMed

    Gámez, M; López, I; Molnár, S

    2008-09-01

    The monitoring and analysis of the processes taking place in an ecosystem is a key issue for a sustainable human activity. A system of populations, as the biotic component of a complex ecosystem is usually affected by the variation of its abiotic environment. Even in nearly natural ecosystems an abiotic effect like climatic implications of global warming may cause important changes in the dynamics of the population system. In ecosystems involving field cultivation or any industrial activity; the abiotic parameter in question may be the concentration of a substance, changing, e.g. as a result of pollution, application of a pesticide, or a fertilizer, etc. In many cases the observation of the densities of each population may be technically complicated or expensive, therefore the question arises whether from the observation of the densities of certain (indicator) populations, the whole state process of the population system can be uniquely recovered. The paper is aimed at a methodological development of the state monitoring, under the conditions of a changing environment. It is shown, how the technique of mathematical systems theory can be applied not only for the approximate calculation of the state process on the basis of the observed data, even under the effect of an exogene abiotic change with known dynamics; but in certain cases, also for the estimation of the unknown biological effect of the change of an abiotic parameter. The proposed methodology is applied to simple illustrative examples concerning a three-species predator-prey system.

  11. Determining molecular responses to environmental change in soybeans

    USDA-ARS?s Scientific Manuscript database

    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...

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Healthy Cities, local environmental action and climate change.

    PubMed

    Bentley, Michael

    2007-09-01

    This paper reports results of a study that explored the relationship between the local environmental actions of Healthy Cities programs and the adverse health impacts of climate change. The analysis is primarily based on a limited literature review of climate change and health, with particular attention to the relationships between Healthy Cities and climate change, and on documentary analysis of information from organization reports and website content associated with Healthy Cities programs in Europe and Australia. Four semi-structured interviews with key people in two Healthy Cities programs in Europe and Australia were conducted to provide information to supplement and complement the published information and to verify theme identification. The main findings of this study are that, although there is no explicit connection between the local activities of Healthy Cities programs and the potential (or actual) adverse health impacts of climate change, Healthy Cities programs are involved in many local environmental actions and some of these actions, for example, those relating to improving air quality and reducing pollution, are linked implicitly to the health impacts of climate change. Through their local relationships and their participation in regional networks, Healthy Cities are able to make connections between local environmental actions and the health impacts of climate change. Furthermore, expanding Healthy Cities to include eco-social sustainability as a central aim not only has the potential to strengthen the links between local environmental actions and climate change, but also presents a relevant health development setting for exploring the social and environmental sustainability of cities.

  2. 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.

  3. 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

  4. 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.

  5. 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,…

  6. 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,…

  7. Relationship between climate change and environmental risk's of forestry technologies

    NASA Astrophysics Data System (ADS)

    Pécsinger, Judit; Polgár, András

    2017-04-01

    Environmental risk analysis of the technological aspects of forestry is an important complement to the climate research. Commonly used forestry technologies, like cleaning cutting or final harvest, causes various environmental effects which presents different environmental risks. Based on their material and energy deductions and emissions, they can contribute in different ways to global environmental problems such as climate change. Using environmental risk assessment we explored the newly emerging environmental hazards of the typical forestry technologies due to climate change. These hazards are known in terms of their properties (eg. aridification, toxic load etc), but the spatial appearance is novel. We investigated the possible stressor-response relationships, then estimated the expected exposure. In the risk characterization, we summarized information received in the previous steps. As a result we set up the risk matrices of the working systems of intermediate cutting and final harvest in the stands of beech, oak and spruce. In the matrices, the technologies ranked by values of Global Warming Potential (GWP 100 years) were placed in relation of the average temperature change (dT [° C]) of climate change scenarios. We defined the environmental risks in text form, specifying classes of risks: - I. Class: high risk - II. Class: medium risk - III. Class: low risk. The use of a risk matrix is an important complement to climate change decision-making when selecting the forestry technologies. It serves as a guideline for both foresters and decision makers. Keywords: climate change / environmental risk / risk assessment / forest technology's risk matrix Acknowledgement: This research has been supported by the Agroclimate.2 VKSZ_12-1- 2013-0034 project.

  8. Geochemistry and radiometric dating of a Middle Pleistocene peat

    SciTech Connect

    Rowe, P.J.; Atkinson, T.C.; Richards, D.A.; Bottrell, S.H.; Cliff, R.A.

    1997-10-01

    Uranium, lead, and sulphur data for a Middle Pleistocene interglacial peat deposit from Norfolk, UK, suggest that uptake of these elements was synchronous and confined to a single early diagenetic episode, probably coeval with peat formation. Sulphur isotope data indicate that reducing conditions have been maintained within the deposit throughout its history. Both uranium and lead concentration profiles show a marked discontinuity near the middle of the bed, probably indicating an environmental change, possibly emergence. The lead isotope data are compatible with a single lead component below the discontinuity and two components above. Groundwater is thought to be the dominant source of lead with an additional airfall component present in the upper peat. The uranium and lead concentration profiles below the discontinuity and the sulfur isotope profile throughout the peat support the view that these elements were sequestered from upwelling groundwaters. 35 refs., 9 figs., 3 tabs.

  9. 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%.

  10. 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.

  11. 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

  12. 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.

  13. 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).

  14. 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…

  15. 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…

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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

  2. Environmental and Water Decision-Making in a Changing Climate

    NASA Astrophysics Data System (ADS)

    Jain, Shaleen; Pulwarty, Roger S.; Melis, Theodore S.

    2006-04-01

    Understanding and responding to the impacts of climate variability and change on water and environmental systems requires analysis, modeling methodologies, and tools that accommodate incomplete knowledge and uncertainty that themselves evolve over time. The broad scope of this problem necessitates a multidimensional dialogue among research and policy groups that span disciplinary boundaries. Integration of this knowledge is required to develop adaptive capacity (i.e., necessary knowledge, preparedness, and reliable decision-making capacity to act by all partners in the information chain) and resilience. In this context, resilience can be taken to mean the degree to which the environmental system can absorb both abrupt and gradual changes and build capacity for learning and adaptation. As part of the 2005 AGU Fall Meeting, the session ``Integrated environmental and water decision-making in a changing climate'' was convened under the primary sponsorship of the Global Environmental Change Focus Group, with cosponsorship from other sections. The session served as a venue for a discussion of case studies, conceptual frameworks, and modeling that examined one or more components of the connected climate-water-environmental systems on local, regional, and continental scales. Combining analyses of historical hydroclimatic variations and trends with 21st-century climate change scenarios to quantify uncertainties and associated geographical sensitivities was also a key area of interest.

  3. 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.

  4. 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.

  5. New frontiers for environmental epidemiology in a changing world.

    PubMed

    Tonne, Cathryn; Basagaña, Xavier; Chaix, Basile; Huynen, Maud; Hystad, Perry; Nawrot, Tim S; Slama, Remy; Vermeulen, Roel; Weuve, Jennifer; Nieuwenhuijsen, Mark

    2017-07-01

    In the next 25years, transformative changes, in particular the rapid pace of technological development and data availability, will require environmental epidemiologists to prioritize what should (rather than could) be done to most effectively improve population health. In this essay, we map out key driving forces that will shape environmental epidemiology in the next 25years. We also identify how the field should adapt to best take advantage of coming opportunities and prepare for challenges. Future environmental epidemiologists will face a world shaped by longer lifespans but also larger burdens of chronic health conditions; shifting populations by region and into urban areas; and global environmental change. Rapidly evolving technologies, particularly in sensors and OMICs, will present opportunities for the field. How should it respond? We argue, the field best adapts to a changing world by focusing on healthy aging; evidence gaps, especially in susceptible populations and low-income countries; and by developing approaches to better handle complexity and more formalized analysis. Environmental epidemiology informing disease prevention will continue to be valuable. However, the field must adapt to remain relevant. In particular, the field must ensure that public health importance drives research questions, while seizing the opportunities presented by new technologies. Environmental epidemiologists of the future will require different, refined skills to work effectively across disciplines, ask the right questions, and implement appropriate study designs in a data-rich world. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  6. 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. © 2015 The Author(s).

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

    PubMed Central

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

    2015-01-01

    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. PMID:26336175

  8. 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

  9. 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.

  10. Assessing and managing freshwater ecosystems vulnerable to environmental change.

    PubMed

    Angeler, David G; Allen, Craig R; Birgé, Hannah E; Drakare, Stina; McKie, Brendan G; Johnson, Richard K

    2014-01-01

    Freshwater ecosystems are important for global biodiversity and provide essential ecosystem services. There is consensus in the scientific literature that freshwater ecosystems are vulnerable to the impacts of environmental change, which may trigger irreversible regime shifts upon which biodiversity and ecosystem services may be lost. There are profound uncertainties regarding the management and assessment of the vulnerability of freshwater ecosystems to environmental change. Quantitative approaches are needed to reduce this uncertainty. We describe available statistical and modeling approaches along with case studies that demonstrate how resilience theory can be applied to aid decision-making in natural resources management. We highlight especially how long-term monitoring efforts combined with ecological theory can provide a novel nexus between ecological impact assessment and management, and the quantification of systemic vulnerability and thus the resilience of ecosystems to environmental change.

  11. 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.

  12. 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.

  13. Expansion of the known distribution of Asiatic mouflon (Ovis orientalis) in the Late Pleistocene of the Southern Levant.

    PubMed

    Yeomans, Lisa; Martin, Louise; Richter, Tobias

    2017-08-01

    Wild sheep (Ovis orientalis) bones recovered from the Natufian site of Shubayqa 1 demonstrate a wider distribution of mouflon in the Late Pleistocene of the Southern Levant than previously known. Early Epipalaeolithic sites are common in the limestone steppe region of eastern Jordan but have yielded only a handful of caprine bones that cannot be identified to species level and few faunal remains from excavated Late Epipalaeolithic sites have been reported. Analysis of animal bone from Shubayqa 1 suggests a significant population of wild sheep could be found concentrated in the basalt desert environment of eastern Jordan during the Late Pleistocene, especially where higher rainfall over the Jebel Druze provided more water. A population of wild sheep was still present in the Pre-Pottery Neolithic A when the nearby site of Shubayqa 6 was occupied. Hunting of diverse, locally available resources including wild sheep at the end of the Pleistocene illustrates the flexible and adaptive exploitation strategies that hunter-forager groups engaged in. This provides further evidence to the increasing body of data showing the creative and opportunistic approach of terminal Pleistocene groups allowing continued occupation even in more marginal environments in a period of environmental change.

  14. Expansion of the known distribution of Asiatic mouflon (Ovis orientalis) in the Late Pleistocene of the Southern Levant

    PubMed Central

    Martin, Louise; Richter, Tobias

    2017-01-01

    Wild sheep (Ovis orientalis) bones recovered from the Natufian site of Shubayqa 1 demonstrate a wider distribution of mouflon in the Late Pleistocene of the Southern Levant than previously known. Early Epipalaeolithic sites are common in the limestone steppe region of eastern Jordan but have yielded only a handful of caprine bones that cannot be identified to species level and few faunal remains from excavated Late Epipalaeolithic sites have been reported. Analysis of animal bone from Shubayqa 1 suggests a significant population of wild sheep could be found concentrated in the basalt desert environment of eastern Jordan during the Late Pleistocene, especially where higher rainfall over the Jebel Druze provided more water. A population of wild sheep was still present in the Pre-Pottery Neolithic A when the nearby site of Shubayqa 6 was occupied. Hunting of diverse, locally available resources including wild sheep at the end of the Pleistocene illustrates the flexible and adaptive exploitation strategies that hunter-forager groups engaged in. This provides further evidence to the increasing body of data showing the creative and opportunistic approach of terminal Pleistocene groups allowing continued occupation even in more marginal environments in a period of environmental change. PMID:28878989

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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

  3. 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.

  4. Environmental water demand assessment under climate change conditions.

    PubMed

    Sarzaeim, Parisa; Bozorg-Haddad, Omid; Fallah-Mehdipour, Elahe; Loáiciga, Hugo A

    2017-07-01

    Measures taken to cope with the possible effects of climate change on water resources management are key for the successful adaptation to such change. This work assesses the environmental water demand of the Karkheh river in the reach comprising Karkheh dam to the Hoor-al-Azim wetland, Iran, under climate change during the period 2010-2059. The assessment of the environmental demand applies (1) representative concentration pathways (RCPs) and (2) downscaling methods. The first phase of this work projects temperature and rainfall in the period 2010-2059 under three RCPs and with two downscaling methods. Thus, six climatic scenarios are generated. The results showed that temperature and rainfall average would increase in the range of 1.7-5.2 and 1.9-9.2%, respectively. Subsequently, flows corresponding to the six different climatic scenarios are simulated with the unit hydrographs and component flows from rainfall, evaporation, and stream flow data (IHACRES) rainfall-runoff model and are input to the Karkheh reservoir. The simulation results indicated increases of 0.9-7.7% in the average flow under the six simulation scenarios during the period of analysis. The second phase of this paper's methodology determines the monthly minimum environmental water demands of the Karkheh river associated with the six simulation scenarios using a hydrological method. The determined environmental demands are compared with historical ones. The results show that the temporal variation of monthly environmental demand would change under climate change conditions. Furthermore, some climatic scenarios project environmental water demand larger than and some of them project less than the baseline one.

  5. 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. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Environmental Education for Behaviour Change: Which actions should be targeted?

    NASA Astrophysics Data System (ADS)

    Boyes, Edward; Stanisstreet, Martin

    2012-07-01

    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 general environmental attitudes and knowledge, and his or her willingness to undertake pro-environmental actions, so this study focuses on some specific issues. Using survey methods to produce quantitative data about students' beliefs concerning the usefulness of specific actions and their willingness to adopt them, novel indices have been constructed that indicate the potential of education to increase students' willingness to undertake those actions. The findings imply that altering a student's belief about certain issues will have little effect on their willingness to act. This can be because most students, even those with only a weak belief in the efficacy, are prepared to take action anyway. Conversely, it can be because a majority, including those convinced about the efficacy, are not prepared to take action. Education about such actions, where there is only a weak link between believed effectiveness and willingness to act, may be ineffective in terms of changing practice, because other factors such as social norms and situational influences dominate. For such actions other strategies may be required. For another set of actions, however, the benefits of education in changing practice seemed more positive; increasing recycling, reducing the use of artificial fertilisers and planting more trees are examples.

  7. Great Basin Archaeology During the Middle Holocene: a Reflection of Environmental Change

    NASA Astrophysics Data System (ADS)

    Wriston, T.

    2008-12-01

    Varying types of proxy data in the Great Basin of the western United States suggest that the environment changed dramatically during the mid-Holocene. Lake, marsh, and spring systems dried; and dune fields, first established at the end of the Pleistocene, where again activated as sediments were swept from drying basin lowlands. Plant communities reorganized and migrated along elevation gradients to adapt to these changing conditions, and animal populations followed. However, recent data suggests that conditions during the middle Holocene were variable. Minimally, three distinct periods can be recognized, herein named: the Initial Middle Holocene (ca. 8000 to 5800 cal yr BP), the Middle Holocene Gap (ca. 5800 to 5200 cal yr BP), and the Terminal Middle Holocene (ca. 5200 to 4000 cal yr BP). Depending on location and the type of proxy data studied, these periods can vary in their character and timing, but their sequence is increasingly recognized in records of both regional and global-scale. The Initial Middle Holocene is the driest and most volatile of the three periods, with a shift from winter-to summer-dominated precipitation, often delivered by torrential storms. Conversely, the Middle Holocene Gap is a relatively mesic interval with increased winter precipitation and cooler temperatures. A shift towards drier conditions is again evidenced during the Terminal Middle Holocene; however, conditions are never again as dry or as volatile as during the Initial Middle Holocene. The archaeological signature of the Great Basin during the middle Holocene reflects adaptation to this changing environment. During the Initial Middle Holocene, archaeological sites are relatively scarce, and when present, are near water sources substantial enough to persist through the intense drought. The uplands became a focus of sustained seasonal use for the first time as increasingly diverse resources and environments are routinely exploited. It follows that milling gear is a regular and

  8. Genetic variation in the southern pines: evolution, migration, and adaptation following the pleistocene

    Treesearch

    Ronald Schmidtling

    2007-01-01

    Climate has certainly changed over time, requiring genetic change or migration of forest tree species. Little is known about the location of the southern pines during the Pleistocene glaciation, which ended around 14,000 years ago. Macrofossils of spruce (Picea spp.) dating from the late Pleistocene, which are typical of climates much cooler than...

  9. 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.

  10. 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.

  11. Social vulnerability and environmental change along urban-rural interfaces

    Treesearch

    John Schelhas; Sarah Hitchner; Cassandra Johnson

    2012-01-01

    As the world becomes increasingly urbanized and interconnected, the distinction between urban and rural areas is diminishing. Creation of new urban–rural interface areas causes immediate changes in local natural and social environments, and theseareas are also susceptible to both short-term and long-term environmental changes. Different groups of people...

  12. 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.

  13. 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".

  14. 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…

  15. 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…

  16. 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

  17. 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.

  18. 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

  19. Cold-water coral carbonate mounds as unique palaeo-archives: the Plio-Pleistocene Challenger Mound record (NE Atlantic)

    NASA Astrophysics Data System (ADS)

    Thierens, M.; Browning, E.; Pirlet, H.; Loutre, M.-F.; Dorschel, B.; Huvenne, V. A. I.; Titschack, J.; Colin, C.; Foubert, A.; Wheeler, A. J.

    2013-08-01

    Through the interplay of a stabilising cold-water coral framework and a dynamic sedimentary environment, cold-water coral carbonate mounds create distinctive centres of bio-geological accumulation in often complex (continental margin) settings. The IODP Expedition 307 drilling of the Challenger Mound (eastern Porcupine Seabight; NE Atlantic) not only retrieved the first complete developmental history of a coral carbonate mound, it also exposed a unique, Early-Pleistocene sedimentary sequence of exceptional resolution along the mid-latitudinal NE Atlantic margin. In this study, a comprehensive assessment of the Challenger Mound as an archive of Quaternary palaeo-environmental change and long-term coral carbonate mound development is presented. New and existing environmental proxy records, including clay mineralogy, planktonic foraminifer and calcareous nannofossil biostratigraphy and assemblage counts, planktonic foraminifer oxygen isotopes and siliciclastic particle-size, are thereby discussed within a refined chronostratigraphic and climatic context. Overall, the development of the Challenger Mound shows a strong affinity to the Plio-Pleistocene evolution of the Northern Hemisphere climate system, albeit not being completely in phase with it. The two major oceanographic and climatic transitions of the Plio-Pleistocene - the Late Pliocene/Early Pleistocene intensification of continental ice-sheet development and the mid-Pleistocene transition to the more extremely variable and more extensively glaciated late Quaternary - mark two major thresholds in Challenger Mound development: its Late Pliocene (>2.74 Ma) origin and its Middle-Late Pleistocene to recent decline. Distinct surface-water perturbations (i.e. water-mass/polar front migrations, productivity changes, melt-water pulses) are identified throughout the sequence, which can be linked to the intensity and extent of ice development on the nearby British-Irish Isles since the earliest Pleistocene. Glaciation

  20. 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.

  1. Consideration of climate change on environmental impact assessment in Spain

    SciTech Connect

    Enríquez-de-Salamanca, Álvaro; Martín-Aranda, Rosa M.; Díaz-Sierra, Rubén

    2016-02-15

    Most of the projects subject to environmental impact assessment (EIA) are closely related to climate change, as they contribute to or are affected by it. The growing certainty about climate change and its impacts makes its consideration an essential part of the EIA process, as well as in strategic environmental assessment (SEA). This paper examines how climate change (CC) has been taken into account in EIA in Spain through the analysis of 1713 environmental records of decision (RODs) of projects submitted for EIA. In 2013 Spain approved one of the most advanced laws in terms of CC consideration in environmental assessment, although it had not yet accumulated extensive practice on the issue. This contrasts with the situation of countries like Canada or the USA, which have a significant body of experience without specific legal requirements. Only 14% of the RODs analysed included references to CC, and in more than half of the cases it was a mere citation. Thermal power plants, which are subject to specific GHG regulations, show the highest consideration, while transport infrastructures, which are important contributors to CC, show a very low consideration. Almost all the references are related to their contribution to CC, while consideration of the effects of CC is minimal. The increasingly common incorporation of CC into SEA, should not imply its exclusion from EIA, because both processes have different aims and uses. Including the obligation to consider CC in the EIA regulations is highly desirable, but probably not enough without other measures, such as practical guidance, training and motivational programmes for practitioners and evaluators. But even these actions cannot ensure effective and adequate assessments of CC. Probably more resources should be spent on creating greater awareness in all the agents involved in EIA. - Highlights: • We analyse how the climate change is considered in EIA in Spain. • Few projects seriously assess climate change.

  2. 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

  3. Environmental change at Kartchner Caverns: trying to separate natural and anthropogenic changes

    Treesearch

    Rickard S. Toomey; Ginger Nolan

    2005-01-01

    Cave temperature and moisture levels are important factors in the environmental health of Kartchner Caverns. Monitoring indicates the cave has warmed and moisture levels have fallen over the past 14 years. Timing and patterns of change within the cave suggest that changes are due to development as a show cave. However, changes in other caves, surface temperature and...

  4. The influence of life history and diet on the distribution of catarrhine primates during the Pleistocene in eastern Asia.

    PubMed

    Jablonski, N G; Whitfort, M J; Roberts-Smith, N; Qinqi, X

    2000-08-01

    Environmental changes during the Pleistocene in eastern Asia had profound impacts on the distributions of mammalian groups. Critical for many mammals were the southward latitudinal shifts of the tropical and subtropical vegetational zones, and decreases in the areas of these zones. Examination of the responses of members of a single clade, the Catarrhini, indicates that the main catarrhine genera of eastern Asia responded individually to the environmental changes in the Pleistocene. These responses were influenced by the life history parameters and diets of the genera involved. Those animals (macaques, langurs) with shorter gestation times, shorter weaning periods, shorter interbirth intervals, higher intrinsic rates of increase of population, and abilities to survive on a wider variety of vegetation in seasonal habitats were less adversely affected than those (gibbons, orangutans and the giant extinct hominoid, Gigantopithecus) with more protracted reproductive schedules, lower intrinsic rates of population increase and preferences for the higher quality foods (especially ripe fruits) of less seasonal environments. Hominids, while displaying "hyper-ape" life history parameters, increasingly overcame the constraints of these parameters through extrasomatic means not available to other catarrhines. This ability made possible their colonization, by the Late Pleistocene, of highly seasonal habitats such as tundra, which were off-limits to non-culture-bearing catarrhines.

  5. 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.

  6. 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

  7. 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.

  8. Predicting Responses to Contemporary Environmental Change Using Evolutionary Response Architectures.

    PubMed

    Bay, Rachael A; Rose, Noah; Barrett, Rowan; Bernatchez, Louis; Ghalambor, Cameron K; Lasky, Jesse R; Brem, Rachel B; Palumbi, Stephen R; Ralph, Peter

    2017-05-01

    Rapid environmental change currently presents a major threat to global biodiversity and ecosystem functions, and understanding impacts on individual populations is critical to creating reliable predictions and mitigation plans. One emerging tool for this goal is high-throughput sequencing technology, which can now be used to scan the genome for signs of environmental selection in any species and any system. This explosion of data provides a powerful new window into the molecular mechanisms of adaptation, and although there has been some success in using genomic data to predict responses to selection in fields such as agriculture, thus far genomic data are rarely integrated into predictive frameworks of future adaptation in natural populations. Here, we review both theoretical and empirical studies of adaptation to rapid environmental change, focusing on areas where genomic data are poised to contribute to our ability to estimate species and population persistence and adaptation. We advocate for the need to study and model evolutionary response architectures, which integrate spatial information, fitness estimates, and plasticity with genetic architecture. Understanding how these factors contribute to adaptive responses is essential in efforts to predict the responses of species and ecosystems to future environmental change.

  9. 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

  10. Intestinal microbiota is a plastic factor responding to environmental changes.

    PubMed

    Candela, Marco; Biagi, Elena; Maccaferri, Simone; Turroni, Silvia; Brigidi, Patrizia

    2012-08-01

    Traditionally regarded as stable through the entire lifespan, the intestinal microbiota has now emerged as an extremely plastic entity, capable of being reconfigured in response to different environmental factors. In a mutualistic context, these microbiome fluctuations allow the host to rapidly adjust its metabolic and immunologic performances in response to environmental changes. Several circumstances can disturb this homeostatic equilibrium, inducing the intestinal microbiota to shift from a mutualistic configuration to a disease-associated profile. A mechanistic comprehension of the dynamics involved in this process is needed to deal more rationally with the role of the human intestinal microbiota in health and disease. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. 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.

  12. 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. Copyright © 2015, American Association for the Advancement of Science.

  13. 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.

  14. Should I stay or should I go: biogeographic and evolutionary history of a polyploid complex (Chrysanthemum indicum complex) in response to Pleistocene climate change in China.

    PubMed

    Li, Jing; Wan, Qian; Guo, Yan-Ping; Abbott, Richard J; Rao, Guang-Yuan

    2014-02-01

    Quaternary climatic oscillations greatly influenced the distribution and pattern of biodiversity in the Northern Hemisphere. Here we examine how such oscillations in South East Asia may have affected the demographic and evolutionary history of a polyploid plant complex associated with semi-dry habitats. We analyzed plastid and nuclear ribosomal DNA (rDNA) internal transcribed spacer (ITS) sequence variation within the Chrysanthemum indicum complex (Asteraceae), which comprises diploid and polyploid plants distributed throughout China. In total, 368 individuals from 47 populations across the geographical range of the complex were analyzed. We show that the relatively widespread tetraploid form of C. indicum expanded its range southward in the Pleistocene, possibly during the most recent or previous glacial period when conditions became drier and forests retreated in southern China. In marked contrast, diploid and other polyploid members of the complex failed to expand their ranges at these times or have since undergone range contractions in contrast to tetraploid C. indicum. We conclude that hybridization and gene flow between taxa occurred frequently during the evolutionary history of the complex, causing considerable sharing of chlorotypes and ITS types. Nevertheless, taxa within ploidy levels could be largely distinguished according to chlorotype and/or ITS type. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  15. 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…

  16. 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. © 2010 ISZS, Blackwell Publishing and IOZ/CAS.

  17. 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. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Use of dendrochronology to promote understanding of environmental change

    NASA Astrophysics Data System (ADS)

    McCormick, Cynthia Stager

    The purpose of this research was to determine how dendrochronology can be used in an experiential unit to enhance high school students' understanding of environmental change. Dendrochronology, the visual examination of tree ring cross sections provides opportunities to relate environmental change to growth patterns of trees and can be used to show the students both how scientists can investigate the past and how the environment can affect trees. Students engaged in a 10-day unit that employed a variety of constructivist learning activities to investigate environmental change, climate change, and tree growth. The culminating activity was student-created experiments that investigated various aspects of the relationship of trees to their environment. This research was a mixed method design and was conducted at a small public high school in the Deep South. The school is a Title One school on a four by four block schedule and is located in a rural area where forestry is one of the major industries. Twenty five juniors and seniors who were members of two environmental science classes were the participants in the research. As evaluated by the Wilcoxon matched-pair signed rank test, students scored significantly higher on the posttest (P < .01) than on the pretest with average scores of 9.52 on the pretest and 18.76 on the posttest. Most of these gains were in questions that evaluated the students understanding of climate change, tree anatomy and statistical analyses of tree growth data. The qualitative components of the research supported that these were the areas of greatest growth and revealed that the students greatly enjoyed participating in investigations of their own.

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

    PubMed

    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

    2017-03-01

    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.

  20. 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

  1. 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

  2. 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

  3. Antarctica and Global Environmental Change - Lessons from the Past Inform Climate Change Policy Today

    NASA Astrophysics Data System (ADS)

    Dunbar, R. B.; Scientific Team Of Odp Drilling Leg 318; Andrill Science Team

    2011-12-01

    Antarctic's continental ice, sea ice, and the broader Southern Ocean form a coupled and complex climate system that interacts in important yet poorly understood ways with the low and mid-latitudes. Because of its unusual sovereignty status and the fact that there is no indigenous human population, information about climate change in Antarctica penetrates the policy world less readily than findings from other regions. Yet, Antarctica's potential to impact climate change globally is disproportionately large. Vulnerable portions of the ice sheet may contribute up to 3 to 5 meters of sea level rise in the coming centuries, including significant amounts within the next 50 years. Loss of sea ice and other changes in the Southern Ocean may reduce oceanic uptake of excess atmospheric carbon dioxide, exacerbating global warming worldwide. Antarctica's impact on the Southern Hemisphere wind field is now well-established, contributing to ongoing decadal-scale perturbations in continental precipitation as well as major reorganizations of Southern Ocean food chains. Recent scientific drilling programs in the Ross Sea and off Wilkes Land, Antarctica, provide valuable insights into past climatic and biogeochemical change in Antarctica, insights of great relevance to international and national climate change policy. In this paper, we discuss polar amplification, sea level variability coupled to Antarctic ice volume, and response timescales as seen through the lens of past climate change. One key result emerging from multiple drilling programs is recognition of unanticipated dynamism in the Antarctic ice sheet during portions of the Pliocene (at a time with pCO2 levels equivalent to those anticipated late this century) as well as during "super-interglacials" of the Pleistocene. Evidence for substantially warmer ocean temperatures and reduced sea ice cover at these times suggests that polar amplification of natural climate variability, even under scenarios of relative small amounts

  4. 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

  5. Changing climate, human evolution, and the revival of environmental determinism.

    PubMed

    Livingstone, David N

    2012-01-01

    The role of climatic change in determining the shape of human evolution, a theme that came to prominence during the early years of the twentieth century, has resurfaced with renewed vigor. The author examines the rise and resurgence of the modern history of the idea that hominid evolutionary pathways have been trigged by climatic causes to illustrate the continuing vitality of environmental determinism and to highlight some continuities between early-twentieth-century and contemporary archaeoanthropology.

  6. 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

  7. 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.

  8. Habitat complexity, environmental change and personality: A tropical perspective.

    PubMed

    Pamela Delarue, Emma Michelle; Kerr, Sarah Emily; Lee Rymer, Tasmin

    2015-11-01

    Tropical rainforests are species-rich, complex ecosystems. They are increasingly being negatively affected by anthropogenic activity, which is rapidly and unpredictably altering their structure and complexity. These changes in habitat state may expose tropical animals to novel and unpredictable conditions, potentially increasing their extinction risk. However, an animal's ability to cope with environmental change may be linked to its personality. While numerous studies have investigated environmental influences on animal personalities, few are focused on tropical species. In this review, we consider how behavioural syndromes in tropical species might facilitate coping under, and adapting to, increasing disturbance. Given the complexity of tropical rainforests, we first discuss how habitat complexity influences personality traits and physiological stress in general. We then explore the ecological and evolutionary implications of personality in the tropics in the context of behavioural flexibility, range expansion and speciation. Finally, we discuss the impact that anthropogenic environmental change may have on the ecological integrity of tropical rainforests, positing scenarios for species persistence. Maintaining tropical rainforest complexity is crucial for driving behavioural flexibility and personality type, both of which are likely to be key factors facilitating long term persistence in disturbed habitats. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. 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.

  10. 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.

  11. Empirical investigation of the mid-Pleistocene transition

    NASA Astrophysics Data System (ADS)

    Loskutov, Evgeny; Mukhin, Dmitry; Gavrilov, Andrey; Feigin, Alexander

    2017-04-01

    In this work we apply a new empirical method for the analysis of complex spatially distributed systems to the analysis of paleoclimatology data. We are focused on the investigation of critical transitions (the abrupt changes in climate dynamics) in process with paleo timescales. Namely we investigated so-called mid-Pleistocene transition which led to change of dominate cycles of glacial variability in Pleistocene. We demonstrate the first results of applying our empirical methods to analysis of paleoclimate variability. In particular, we discuss the possibility of detecting, identifying and prediction the mid-Pleistocene transition by means of nonlinear empirical modeling using the paleoclimate record time series. The study is supported by Government of Russian Federation (agreement #14.Z50.31.0033 with the Institute of Applied Physics of RAS).

  12. Middle Holocene rapid environmental changes and human adaptation in Greece

    NASA Astrophysics Data System (ADS)

    Lespez, Laurent; Glais, Arthur; Lopez-Saez, José-Antonio; Le Drezen, Yann; Tsirtsoni, Zoï; Davidson, Robert; Biree, Laetitia; Malamidou, Dimitra

    2016-03-01

    Numerous researchers discuss of the collapse of civilizations in response to abrupt climate change in the Mediterranean region. The period between 6500 and 5000 cal yr BP is one of the least studied episodes of rapid climate change at the end of the Late Neolithic. This period is characterized by a dramatic decline in settlement and a cultural break in the Balkans. High-resolution paleoenvironmental proxy data obtained in the Lower Angitis Valley enables an examination of the societal responses to rapid climatic change in Greece. Development of a lasting fluvio-lacustrine environment followed by enhanced fluvial activity is evident from 6000 cal yr BP. Paleoecological data show a succession of dry events at 5800-5700, 5450 and 5000-4900 cal yr BP. These events correspond to incursion of cold air masses to the eastern Mediterranean, confirming the climatic instability of the middle Holocene climate transition. Two periods with farming and pastural activities (6300-5600 and 5100-4700 cal BP) are evident. The intervening period is marked by environmental changes, but the continuous occurrence of anthropogenic taxa suggests the persistence of human activities despite the absence of archaeological evidence. The environmental factors alone were not sufficient to trigger the observed societal changes.

  13. 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

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

    PubMed

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

    2007-12-26

    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.

  15. 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).

  16. Late Pleistocene Southeast Amazonia Paleoenvironmental reconstruction inferred by bulk, isotopic and molecular organic matter. Saci lake-Para-Brazil

    NASA Astrophysics Data System (ADS)

    Martins, G. S.; Cordeiro, R. C.; Turcq, B.; Moreira, L. S.; Bouloubassi, I.; Sifeddine, A.

    2014-12-01

    Bulk, Isotope and biolomecular analysis supported by 22 14C AMS dates, allowed the reconstruction of environmental changes during the last 35 000 years BP in the Southeast Amazonian basin. A terrestrial origin has been inferred for the odd carbon-numbered long-chain (>C27) n-alkanes. The entire n-alkane δ13C range between -31.7‰ and -36.8‰, which is the isotopic range occupied by C3 vegetation. The C29:C31 ratio shows that a gramineae contribution is higher during the Pleistocene than in Holocene. The n-alkanes concentration decrease between 32 000 - 18 000, suggesting a increase in arid conditions. The ACL index confirm this interpretation showing high values due the Pleistocene linked to more hydrological stress. A shift in the abundance of n-alkane and isotopic values are observed across the late Pleistocene glacial-Holocene interglacial climate change, suggesting a climate-induced vegetational change. During the middle Holocene the n-alcanes values decreases indicating rain forest regression accompanied by increase in the ACL values confirming the dry climate conditions. Comparison with other South American records, our record indicates regression/expansion of the rain forest linked to the South American System monsoon activity since 35 kyrs.

  17. 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.

  18. Molluscs and ostracods of the Pleistocene loess deposits in the Halych site (Western Ukraine) and their significance for palaeoenvironmental reconstructions

    NASA Astrophysics Data System (ADS)

    Alexandrowicz, Witold Paweł; Łanczont, Maria; Boguckyj, Andriy B.; Kulesza, Piotr; Dmytruk, Roman

    2014-12-01

    Middle and Late Pleistocene loess-palaeosol sequence (MIS 12-MIS 2) from the Halych site has been divided into four loess beds, which represent different glacial periods and contain four interglacial pedocomplexes, as well as numerous interstadial and interphase palaeosols. Long-term interdisciplinary research, which has been conducted in this site, enables the detailed description of deposit lithology and precise determination of stratigraphic position of