Climate extremes and predicted warming threaten Mediterranean Holocene firs forests refugia

PubMed Central

Camarero, J. Julio; Carrer, Marco; Gutiérrez, Emilia; Alla, Arben Q.; Andreu-Hayles, Laia; Hevia, Andrea; Koutavas, Athanasios; Martínez-Sancho, Elisabet; Nola, Paola; Papadopoulos, Andreas; Pasho, Edmond; Toromani, Ervin

2017-01-01

Warmer and drier climatic conditions are projected for the 21st century; however, the role played by extreme climatic events on forest vulnerability is still little understood. For example, more severe droughts and heat waves could threaten quaternary relict tree refugia such as Circum-Mediterranean fir forests (CMFF). Using tree-ring data and a process-based model, we characterized the major climate constraints of recent (1950–2010) CMFF growth to project their vulnerability to 21st-century climate. Simulations predict a 30% growth reduction in some fir species with the 2050s business-as-usual emission scenario, whereas growth would increase in moist refugia due to a longer and warmer growing season. Fir populations currently subjected to warm and dry conditions will be the most vulnerable in the late 21st century when climatic conditions will be analogous to the most severe dry/heat spells causing dieback in the late 20th century. Quantification of growth trends based on climate scenarios could allow defining vulnerability thresholds in tree populations. The presented predictions call for conservation strategies to safeguard relict tree populations and anticipate how many refugia could be threatened by 21st-century dry spells. PMID:29109266

Climate extremes and predicted warming threaten Mediterranean Holocene firs forests refugia.

PubMed

Sánchez-Salguero, Raúl; Camarero, J Julio; Carrer, Marco; Gutiérrez, Emilia; Alla, Arben Q; Andreu-Hayles, Laia; Hevia, Andrea; Koutavas, Athanasios; Martínez-Sancho, Elisabet; Nola, Paola; Papadopoulos, Andreas; Pasho, Edmond; Toromani, Ervin; Carreira, José A; Linares, Juan C

2017-11-21

Warmer and drier climatic conditions are projected for the 21st century; however, the role played by extreme climatic events on forest vulnerability is still little understood. For example, more severe droughts and heat waves could threaten quaternary relict tree refugia such as Circum-Mediterranean fir forests (CMFF). Using tree-ring data and a process-based model, we characterized the major climate constraints of recent (1950-2010) CMFF growth to project their vulnerability to 21st-century climate. Simulations predict a 30% growth reduction in some fir species with the 2050s business-as-usual emission scenario, whereas growth would increase in moist refugia due to a longer and warmer growing season. Fir populations currently subjected to warm and dry conditions will be the most vulnerable in the late 21st century when climatic conditions will be analogous to the most severe dry/heat spells causing dieback in the late 20th century. Quantification of growth trends based on climate scenarios could allow defining vulnerability thresholds in tree populations. The presented predictions call for conservation strategies to safeguard relict tree populations and anticipate how many refugia could be threatened by 21st-century dry spells.

The key role of dry days in changing regional climate and precipitation regimes

USGS Publications Warehouse

Polade, Suraj; Pierce, David W.; Cayan, Daniel R.; Gershunov, Alexander; Dettinger, Michael D.

2014-01-01

Future changes in the number of dry days per year can either reinforce or counteract projected increases in daily precipitation intensity as the climate warms. We analyze climate model projected changes in the number of dry days using 28 coupled global climate models from the Coupled Model Intercomparison Project, version 5 (CMIP5). We find that the Mediterranean Sea region, parts of Central and South America, and western Indonesia could experience up to 30 more dry days per year by the end of this century. We illustrate how changes in the number of dry days and the precipitation intensity on precipitating days combine to produce changes in annual precipitation, and show that over much of the subtropics the change in number of dry days dominates the annual changes in precipitation and accounts for a large part of the change in interannual precipitation variability.

Species selection under long-term experimental warming and drought explained by climatic distributions.

PubMed

Liu, Daijun; Peñuelas, Josep; Ogaya, Romà; Estiarte, Marc; Tielbörger, Katja; Slowik, Fabian; Yang, Xiaohong; Bilton, Mark C

2018-03-01

Global warming and reduced precipitation may trigger large-scale species losses and vegetation shifts in ecosystems around the world. However, currently lacking are practical ways to quantify the sensitivity of species and community composition to these often-confounded climatic forces. Here we conducted long-term (16 yr) nocturnal-warming (+0.6°C) and reduced precipitation (-20% soil moisture) experiments in a Mediterranean shrubland. Climatic niche groups (CNGs) - species ranked or classified by similar temperature or precipitation distributions - informatively described community responses under experimental manipulations. Under warming, CNGs revealed that only those species distributed in cooler regions decreased. Correspondingly, under reduced precipitation, a U-shaped treatment effect observed in the total community was the result of an abrupt decrease in wet-distributed species, followed by a delayed increase in dry-distributed species. Notably, while partially correlated, CNG explanations of community response were stronger for their respective climate parameter, suggesting some species possess specific adaptations to either warming or drought that may lead to independent selection to the two climatic variables. Our findings indicate that when climatic distributions are combined with experiments, the resulting incorporation of local plant evolutionary strategies and their changing dynamics over time leads to predictable and informative shifts in community structure under independent climate change scenarios. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Transition from a warm and dry to a cold and wet climate in NE China across the Holocene

NASA Astrophysics Data System (ADS)

Zheng, Yanhong; Pancost, Richard D.; Naafs, B. David A.; Li, Qiyuan; Liu, Zhao; Yang, Huan

2018-07-01

Northeast (NE) China lies in the northernmost part of the East Asian Summer monsoon (EASM) region. Although a series of Holocene climatic records have been obtained from lakes and peats in this region, the Holocene hydrological history and its controls remain unclear. More specifically, it is currently debated whether NE China experienced a dry or wet climate during the early Holocene. Here we reconstruct changes in mean annual air temperature and peat soil moisture across the last ∼13,000 year BP using samples from the Gushantun and Hani peat, located in NE China. Our approach is based on the distribution of bacterial branched glycerol dialkyl glycerol tetraethers (brGDGTs) and the abundance of the archaeal isoprenoidal (iso)GDGT crenarchaeol. Using the recently developed peat-specific MAATpeat temperature calibration we find that NE China experienced a relatively warm early Holocene (∼5-7 °C warmer than today), followed by a cooling trend towards modern-day values during the mid- and late Holocene. Moreover, crenarchaeol concentrations, brGDGT-based pH values, and the distribution of 6-methyl brGDGTs, all indicate an increase in soil moisture content from the early to late Holocene in both peats, which is largely consistent with other data from NE China. This trend towards increasing soil moisture/wetter conditions across the Holocene in NE China records contrasts with the trends observed in other parts of the EASM region, which exhibit an early and/or mid-Holocene moisture/precipitation maximum. However, the Holocene soil moisture variations and temperature-moisture relationships (warm-dry and cold-wet) observed in NE China are similar to those observed in the core area of arid central Asia which is dominated by the westerlies. We therefore propose that an increase in the intensity of the westerlies across the Holocene, driven by increasing winter insolation, expanding Arctic sea ice extent and the enhanced Okhotsk High, caused an increase in moisture

Effect of simulated climate warming on the morphological and physiological traits of Elsholtzia haichowensis in copper contaminated soil.

PubMed

Guan, Ming; Jin, Zexin; Li, Junmin; Pan, Xiaocui; Wang, Suizi; Li, Yuelin

2016-01-01

The aim of this study was to investigate the effects of temperature and Cu on the morphological and physiological traits of Elsholtzia haichowensis grown in soils amended with four Cu concentrations (0, 50, 500, and 1000 mg kg(-1)) under ambient temperature and slight warming. At the same Cu concentration, the height, shoot dry weight, total plant dry weight, and root morphological parameters such as length, surface area and tip number of E. haichowensis increased due to the slight warming. The net photosynthetic rate, stomatal conductance, transpiration, light use efficiency were also higher under the slight warming than under ambient temperature. The increased Cu concentrations, total Cu uptake, bioaccumulation factors and tolerance indexes of shoots and roots were also observed at the slight warming. The shoot dry weight, root dry weight, total plant dry weight and the bioaccumulation factors of shoots and roots at 50 mg Cu kg(-1) were significantly higher than those at 500 and 1000 mg Cu kg(-1) under the slight warming. Therefore, the climate warming may improve the ability of E. haichowensis to phytoremediate Cu-contaminated soil, and the ability improvement greatly depended on the Cu concentrations in soils.

Long-term experimental warming alters community composition of ascomycetes in Alaskan moist and dry arctic tundra.

PubMed

Semenova, Tatiana A; Morgado, Luis N; Welker, Jeffrey M; Walker, Marilyn D; Smets, Erik; Geml, József

2015-01-01

Arctic tundra regions have been responding to global warming with visible changes in plant community composition, including expansion of shrubs and declines in lichens and bryophytes. Even though it is well known that the majority of arctic plants are associated with their symbiotic fungi, how fungal community composition will be different with climate warming remains largely unknown. In this study, we addressed the effects of long-term (18 years) experimental warming on the community composition and taxonomic richness of soil ascomycetes in dry and moist tundra types. Using deep Ion Torrent sequencing, we quantified how OTU assemblage and richness of different orders of Ascomycota changed in response to summer warming. Experimental warming significantly altered ascomycete communities with stronger responses observed in the moist tundra compared with dry tundra. The proportion of several lichenized and moss-associated fungi decreased with warming, while the proportion of several plant and insect pathogens and saprotrophic species was higher in the warming treatment. The observed alterations in both taxonomic and ecological groups of ascomycetes are discussed in relation to previously reported warming-induced shifts in arctic plant communities, including decline in lichens and bryophytes and increase in coverage and biomass of shrubs. © 2014 John Wiley & Sons Ltd.

Changing forest water yields in response to climate warming: results from long-term experimental watershed sites across North America.

PubMed

Creed, Irena F; Spargo, Adam T; Jones, Julia A; Buttle, Jim M; Adams, Mary B; Beall, Fred D; Booth, Eric G; Campbell, John L; Clow, Dave; Elder, Kelly; Green, Mark B; Grimm, Nancy B; Miniat, Chelcy; Ramlal, Patricia; Saha, Amartya; Sebestyen, Stephen; Spittlehouse, Dave; Sterling, Shannon; Williams, Mark W; Winkler, Rita; Yao, Huaxia

2014-10-01

Climate warming is projected to affect forest water yields but the effects are expected to vary. We investigated how forest type and age affect water yield resilience to climate warming. To answer this question, we examined the variability in historical water yields at long-term experimental catchments across Canada and the United States over 5-year cool and warm periods. Using the theoretical framework of the Budyko curve, we calculated the effects of climate warming on the annual partitioning of precipitation (P) into evapotranspiration (ET) and water yield. Deviation (d) was defined as a catchment's change in actual ET divided by P [AET/P; evaporative index (EI)] coincident with a shift from a cool to a warm period - a positive d indicates an upward shift in EI and smaller than expected water yields, and a negative d indicates a downward shift in EI and larger than expected water yields. Elasticity was defined as the ratio of interannual variation in potential ET divided by P (PET/P; dryness index) to interannual variation in the EI - high elasticity indicates low d despite large range in drying index (i.e., resilient water yields), low elasticity indicates high d despite small range in drying index (i.e., nonresilient water yields). Although the data needed to fully evaluate ecosystems based on these metrics are limited, we were able to identify some characteristics of response among forest types. Alpine sites showed the greatest sensitivity to climate warming with any warming leading to increased water yields. Conifer forests included catchments with lowest elasticity and stable to larger water yields. Deciduous forests included catchments with intermediate elasticity and stable to smaller water yields. Mixed coniferous/deciduous forests included catchments with highest elasticity and stable water yields. Forest type appeared to influence the resilience of catchment water yields to climate warming, with conifer and deciduous catchments more susceptible to

Changing forest water yields in response to climate warming: results from long-term experimental watershed sites across North America

PubMed Central

Creed, Irena F; Spargo, Adam T; Jones, Julia A; Buttle, Jim M; Adams, Mary B; Beall, Fred D; Booth, Eric G; Campbell, John L; Clow, Dave; Elder, Kelly; Green, Mark B; Grimm, Nancy B; Miniat, Chelcy; Ramlal, Patricia; Saha, Amartya; Sebestyen, Stephen; Spittlehouse, Dave; Sterling, Shannon; Williams, Mark W; Winkler, Rita; Yao, Huaxia

2014-01-01

Climate warming is projected to affect forest water yields but the effects are expected to vary. We investigated how forest type and age affect water yield resilience to climate warming. To answer this question, we examined the variability in historical water yields at long-term experimental catchments across Canada and the United States over 5-year cool and warm periods. Using the theoretical framework of the Budyko curve, we calculated the effects of climate warming on the annual partitioning of precipitation (P) into evapotranspiration (ET) and water yield. Deviation (d) was defined as a catchment's change in actual ET divided by P [AET/P; evaporative index (EI)] coincident with a shift from a cool to a warm period – a positive d indicates an upward shift in EI and smaller than expected water yields, and a negative d indicates a downward shift in EI and larger than expected water yields. Elasticity was defined as the ratio of interannual variation in potential ET divided by P (PET/P; dryness index) to interannual variation in the EI – high elasticity indicates low d despite large range in drying index (i.e., resilient water yields), low elasticity indicates high d despite small range in drying index (i.e., nonresilient water yields). Although the data needed to fully evaluate ecosystems based on these metrics are limited, we were able to identify some characteristics of response among forest types. Alpine sites showed the greatest sensitivity to climate warming with any warming leading to increased water yields. Conifer forests included catchments with lowest elasticity and stable to larger water yields. Deciduous forests included catchments with intermediate elasticity and stable to smaller water yields. Mixed coniferous/deciduous forests included catchments with highest elasticity and stable water yields. Forest type appeared to influence the resilience of catchment water yields to climate warming, with conifer and deciduous catchments more susceptible to

Non-climatic thermal adaptation: implications for species' responses to climate warming.

PubMed

Marshall, David J; McQuaid, Christopher D; Williams, Gray A

2010-10-23

There is considerable interest in understanding how ectothermic animals may physiologically and behaviourally buffer the effects of climate warming. Much less consideration is being given to how organisms might adapt to non-climatic heat sources in ways that could confound predictions for responses of species and communities to climate warming. Although adaptation to non-climatic heat sources (solar and geothermal) seems likely in some marine species, climate warming predictions for marine ectotherms are largely based on adaptation to climatically relevant heat sources (air or surface sea water temperature). Here, we show that non-climatic solar heating underlies thermal resistance adaptation in a rocky-eulittoral-fringe snail. Comparisons of the maximum temperatures of the air, the snail's body and the rock substratum with solar irradiance and physiological performance show that the highest body temperature is primarily controlled by solar heating and re-radiation, and that the snail's upper lethal temperature exceeds the highest climatically relevant regional air temperature by approximately 22°C. Non-climatic thermal adaptation probably features widely among marine and terrestrial ectotherms and because it could enable species to tolerate climatic rises in air temperature, it deserves more consideration in general and for inclusion into climate warming models.

Climatic warming destabilizes forest ant communities

PubMed Central

Diamond, Sarah E.; Nichols, Lauren M.; Pelini, Shannon L.; Penick, Clint A.; Barber, Grace W.; Cahan, Sara Helms; Dunn, Robert R.; Ellison, Aaron M.; Sanders, Nathan J.; Gotelli, Nicholas J.

2016-01-01

How will ecological communities change in response to climate warming? Direct effects of temperature and indirect cascading effects of species interactions are already altering the structure of local communities, but the dynamics of community change are still poorly understood. We explore the cumulative effects of warming on the dynamics and turnover of forest ant communities that were warmed as part of a 5-year climate manipulation experiment at two sites in eastern North America. At the community level, warming consistently increased occupancy of nests and decreased extinction and nest abandonment. This consistency was largely driven by strong responses of a subset of thermophilic species at each site. As colonies of thermophilic species persisted in nests for longer periods of time under warmer temperatures, turnover was diminished, and species interactions were likely altered. We found that dynamical (Lyapunov) community stability decreased with warming both within and between sites. These results refute null expectations of simple temperature-driven increases in the activity and movement of thermophilic ectotherms. The reduction in stability under warming contrasts with the findings of previous studies that suggest resilience of species interactions to experimental and natural warming. In the face of warmer, no-analog climates, communities of the future may become increasingly fragile and unstable. PMID:27819044

Climatic warming destabilizes forest ant communities.

PubMed

Diamond, Sarah E; Nichols, Lauren M; Pelini, Shannon L; Penick, Clint A; Barber, Grace W; Cahan, Sara Helms; Dunn, Robert R; Ellison, Aaron M; Sanders, Nathan J; Gotelli, Nicholas J

2016-10-01

How will ecological communities change in response to climate warming? Direct effects of temperature and indirect cascading effects of species interactions are already altering the structure of local communities, but the dynamics of community change are still poorly understood. We explore the cumulative effects of warming on the dynamics and turnover of forest ant communities that were warmed as part of a 5-year climate manipulation experiment at two sites in eastern North America. At the community level, warming consistently increased occupancy of nests and decreased extinction and nest abandonment. This consistency was largely driven by strong responses of a subset of thermophilic species at each site. As colonies of thermophilic species persisted in nests for longer periods of time under warmer temperatures, turnover was diminished, and species interactions were likely altered. We found that dynamical (Lyapunov) community stability decreased with warming both within and between sites. These results refute null expectations of simple temperature-driven increases in the activity and movement of thermophilic ectotherms. The reduction in stability under warming contrasts with the findings of previous studies that suggest resilience of species interactions to experimental and natural warming. In the face of warmer, no-analog climates, communities of the future may become increasingly fragile and unstable.

Global warming and climate change in Amazonia: Climate-vegetation feedback and impacts on water resources

NASA Astrophysics Data System (ADS)

Marengo, José; Nobre, Carlos A.; Betts, Richard A.; Cox, Peter M.; Sampaio, Gilvan; Salazar, Luis

This chapter constitutes an updated review of long-term climate variability and change in the Amazon region, based on observational data spanning more than 50 years of records and on climate-change modeling studies. We start with the early experiments on Amazon deforestation in the late 1970s, and the evolution of these experiments to the latest studies on greenhouse gases emission scenarios and land use changes until the end of the twenty-first century. The "Amazon dieback" simulated by the HadCM3 model occurs after a "tipping point" of CO2 concentration and warming. Experiments on Amazon deforestation and change of climate suggest that once a critical deforestation threshold (or tipping point) of 40-50% forest loss is reached in eastern Amazonia, climate would change in a way which is dangerous for the remaining forest. This may favor a collapse of the tropical forest, with a substitution of the forest by savanna-type vegetation. The concept of "dangerous climate change," as a climate change, which induces positive feedback, which accelerate the change, is strongly linked to the occurrence of tipping points, and it can be explained as the presence of feedback between climate change and the carbon cycle, particularly involving a weakening of the current terrestrial carbon sink and a possible reversal from a sink (as in present climate) to a source by the year 2050. We must, therefore, currently consider the drying simulated by the Hadley Centre model(s) as having a finite probability under global warming, with a potentially enormous impact, but with some degree of uncertainty.

Warm & wet or warm & dry? - A tree-ring based drought reconstruction from the European lowlands with emphasis on the medieval climate anomaly

NASA Astrophysics Data System (ADS)

Scharnweber, Tobias; Heinrich, Ingo; van der Maaten, Ernst; Heußner, Karl-Uwe; Wilmking, Martin

2016-04-01

Recent advances in reconstructing natural drought variability in Europe, such as the 'Old world drought atlas' (Cook et al., 2015), have sharpened our picture of historical hydroclimatic variability. However, our knowledge lacks high spatial resolution, especially for the northern non-arid regions. For example, it is still under debate if the so called medieval climate anomaly (MCA; ~950-1300 AD), a period of warm temperatures comparable to the contemporary warm phase, was likewise accompanied by increased drought occurrence, or, on the contrary, was rather wet (e.g. Kress et al., 2014). Here, we present a new millennial long drought reconstruction based on a unique dataset of tree rings from historical and modern beech wood from the northeastern European lowlands. Beech has a stable and strong regional summer drought signal over the calibration period of instrumental data (r>0.7 with drought index PDSI over 1900-2010) which, in contrast to other species such as oak, is consistent irrespective of the site/soil conditions the trees grew in. It can be assumed that during medieval times beech wood was available locally and not traded long distances. This strongly reduces the possibility that the new reconstruction mixes different signals of the possibly high spatial variability of precipitation. The extremely high replication of our chronology for the period 1000-1300 AD (peak in town foundations in NE-Germany) with more than 600 series enables a direct comparison with the well replicated recent period 1800-2010. In contrast to the results of Kress et al. (2014) for the Swiss Alps, but in accordance with the 'Old world drought atlas', our first results point at a rather dry and warm MCA in NE-Germany. In addition they support the observation that the hydroclimate of the twentieth century was highly variable compared with the last millennium. References Cook ER, Seager R, Kushnir Y, et al. (2015) Old World megadroughts and pluvials during the Common Era. Science

Quantifying the influence of global warming on unprecedented extreme climate events

PubMed Central

Singh, Deepti; Horton, Daniel E.; Swain, Daniel L.; Touma, Danielle; Charland, Allison; Liu, Yunjie; Haugen, Matz; Tsiang, Michael; Rajaratnam, Bala

2017-01-01

Efforts to understand the influence of historical global warming on individual extreme climate events have increased over the past decade. However, despite substantial progress, events that are unprecedented in the local observational record remain a persistent challenge. Leveraging observations and a large climate model ensemble, we quantify uncertainty in the influence of global warming on the severity and probability of the historically hottest month, hottest day, driest year, and wettest 5-d period for different areas of the globe. We find that historical warming has increased the severity and probability of the hottest month and hottest day of the year at >80% of the available observational area. Our framework also suggests that the historical climate forcing has increased the probability of the driest year and wettest 5-d period at 57% and 41% of the observed area, respectively, although we note important caveats. For the most protracted hot and dry events, the strongest and most widespread contributions of anthropogenic climate forcing occur in the tropics, including increases in probability of at least a factor of 4 for the hottest month and at least a factor of 2 for the driest year. We also demonstrate the ability of our framework to systematically evaluate the role of dynamic and thermodynamic factors such as atmospheric circulation patterns and atmospheric water vapor, and find extremely high statistical confidence that anthropogenic forcing increased the probability of record-low Arctic sea ice extent. PMID:28439005

Quantifying the influence of global warming on unprecedented extreme climate events.

PubMed

Diffenbaugh, Noah S; Singh, Deepti; Mankin, Justin S; Horton, Daniel E; Swain, Daniel L; Touma, Danielle; Charland, Allison; Liu, Yunjie; Haugen, Matz; Tsiang, Michael; Rajaratnam, Bala

2017-05-09

Efforts to understand the influence of historical global warming on individual extreme climate events have increased over the past decade. However, despite substantial progress, events that are unprecedented in the local observational record remain a persistent challenge. Leveraging observations and a large climate model ensemble, we quantify uncertainty in the influence of global warming on the severity and probability of the historically hottest month, hottest day, driest year, and wettest 5-d period for different areas of the globe. We find that historical warming has increased the severity and probability of the hottest month and hottest day of the year at >80% of the available observational area. Our framework also suggests that the historical climate forcing has increased the probability of the driest year and wettest 5-d period at 57% and 41% of the observed area, respectively, although we note important caveats. For the most protracted hot and dry events, the strongest and most widespread contributions of anthropogenic climate forcing occur in the tropics, including increases in probability of at least a factor of 4 for the hottest month and at least a factor of 2 for the driest year. We also demonstrate the ability of our framework to systematically evaluate the role of dynamic and thermodynamic factors such as atmospheric circulation patterns and atmospheric water vapor, and find extremely high statistical confidence that anthropogenic forcing increased the probability of record-low Arctic sea ice extent.

Quantifying the Influence of Global Warming on Unprecedented Extreme Climate Events

NASA Technical Reports Server (NTRS)

Diffenbaugh, Noah S.; Singh, Deepti; Mankin, Justin S.; Horton, Daniel E.; Swain, Daniel L.; Touma, Danielle; Charland, Allison; Liu, Yunjie; Haugen, Matz; Tsiang, Michael;

Climate variability and dengue fever in warm and humid Mexico.

PubMed

Colón-González, Felipe J; Lake, Iain R; Bentham, Graham

2011-05-01

Multiple linear regression models were fitted to look for associations between changes in the incidence rate of dengue fever and climate variability in the warm and humid region of Mexico. Data were collected for 12 Mexican provinces over a 23-year period (January 1985 to December 2007). Our results show that the incidence rate or risk of infection is higher during El Niño events and in the warm and wet season. We provide evidence to show that dengue fever incidence was positively associated with the strength of El Niño and the minimum temperature, especially during the cool and dry season. Our study complements the understanding of dengue fever dynamics in the region and may be useful for the development of early warning systems.

Amazon Basin climate under global warming: the role of the sea surface temperature.

PubMed

Harris, Phil P; Huntingford, Chris; Cox, Peter M

2008-05-27

The Hadley Centre coupled climate-carbon cycle model (HadCM3LC) predicts loss of the Amazon rainforest in response to future anthropogenic greenhouse gas emissions. In this study, the atmospheric component of HadCM3LC is used to assess the role of simulated changes in mid-twenty-first century sea surface temperature (SST) in Amazon Basin climate change. When the full HadCM3LC SST anomalies (SSTAs) are used, the atmosphere model reproduces the Amazon Basin climate change exhibited by HadCM3LC, including much of the reduction in Amazon Basin rainfall. This rainfall change is shown to be the combined effect of SSTAs in both the tropical Atlantic and the Pacific, with roughly equal contributions from each basin. The greatest rainfall reduction occurs from May to October, outside of the mature South American monsoon (SAM) season. This dry season response is the combined effect of a more rapid warming of the tropical North Atlantic relative to the south, and warm SSTAs in the tropical east Pacific. Conversely, a weak enhancement of mature SAM season rainfall in response to Atlantic SST change is suppressed by the atmospheric response to Pacific SST. This net wet season response is sufficient to prevent dry season soil moisture deficits from being recharged through the SAM season, leading to a perennial soil moisture reduction and an associated 30% reduction in annual Amazon Basin net primary productivity (NPP). A further 23% NPP reduction occurs in response to a 3.5 degrees C warmer air temperature associated with a global mean SST warming.

Biomass production in experimental grasslands of different species richness during three years of climate warming

NASA Astrophysics Data System (ADS)

de Boeck, H. J.; Lemmens, C. M. H. M.; Gielen, B.; Malchair, S.; Carnol, M.; Merckx, R.; van den Berge, J.; Ceulemans, R.; Nijs, I.

2007-12-01

Here we report on the single and combined impacts of climate warming and species richness on the biomass production in experimental grassland communities. Projections of a future warmer climate have stimulated studies on the response of terrestrial ecosystems to this global change. Experiments have likewise addressed the importance of species numbers for ecosystem functioning. There is, however, little knowledge on the interplay between warming and species richness. During three years, we grew experimental plant communities containing one, three or nine grassland species in 12 sunlit, climate-controlled chambers in Wilrijk, Belgium. Half of these chambers were exposed to ambient air temperatures (unheated), while the other half were warmed by 3°C (heated). Equal amounts of water were added to heated and unheated communities, so that warming would imply drier soils if evapotranspiration was higher. Biomass production was decreased due to warming, both aboveground (-29%) and belowground (-25%), as negative impacts of increased heat and drought stress in summer prevailed. Increased resource partitioning, likely mostly through spatial complementarity, led to higher shoot and root biomass in multi-species communities, regardless of the induced warming. Surprisingly, warming suppressed productivity the most in 9-species communities, which may be attributed to negative impacts of intense interspecific competition for resources under conditions of high abiotic stress. Our results suggest that warming and the associated soil drying could reduce primary production in many temperate grasslands, and that this will not necessarily be mitigated by efforts to maintain or increase species richness.

Wet-to-dry shift over Southwest China in 1994 tied to the warming of tropical warm pool

NASA Astrophysics Data System (ADS)

Wang, Lin; Huang, Gang; Chen, Wen; Zhou, Wen; Wang, Weiqiang

2018-01-01

The autumn climate in Southwest China (SWC) experienced a notable wet-to-dry shift in 1994. Associated with this change in precipitation, decadal signatures of large-scale atmospheric circulation and SST identify a likely dynamical origin: the tropical warm pool (TWP) consisting of tropical northwest Pacific (TNWP, 3°S-12°N and 110°E-150°E) sector and tropical east Indian Ocean (TEI, 10°S-3°N and 80°E-110°E) sector. A cold-to-warm phase switch of TWP SST occurred in 1994, coinciding exactly with the timing of the regime transition of SWC precipitation. During post-1994 period, warm states in the TNWP and TEI sectors plays in a synergistic fashion to invoke dry decades in SWC. On the one side, warm SST over the TNWP sector excites an anomalous cyclone centered on the South China Sea directed opposite to the climatological moisture transport and strengthened zonal wind to its west accompanied by a weakening of the poleward flux; on the other side, warm SST over the TEI sector acts to intensify inflow into TEI with less concurrent transfer of moisture to SWC and to steer moisture to the northern Arabic Sea and away from the SWC-oriented track. Meanwhile, the troposphere over SWC is capped by subsidence, which is jointly contributed by TNWP and TEI. It then follows a reduced moisture supply, suppressed convective activity, and anomalous divergence in SWC, bringing a precipitation deficit there. In contrast, cold TWP SST during 1961-1994 favors wet conditions in SWC, given a perfectly symmetrical circulation pattern. Further, the dominant role of TWP is confirmed, because the modeled response to TWP SST forcing alone bears a great resemblance to the observed evidence. Finally, it is also found that the teleconnected influence induced by TWP is stronger in southern SWC than in northern SWC, which explains the south-north gradient of interdecadal signal of SWC precipitation.

Changes in South Pacific rainfall bands in a warming climate

NASA Astrophysics Data System (ADS)

Widlansky, M. J.; Timmermann, A.; Stein, K.; McGregor, S.; Schneider, N.; England, M. H.; Lengaigne, M.; Cai, W.

2012-12-01

The South Pacific Convergence Zone (SPCZ) is the largest rainband in the Southern Hemisphere and provides most of the rainfall to Southwest Pacific island nations. In spite of various modeling efforts, it remains uncertain how the SPCZ will respond to greenhouse warming. A multi-model ensemble average of 21st century climate change projections from the current-generation of Coupled General Circulation Models (CGCMs) suggests a slightly wetter Southwest Pacific; however, inter-model uncertainty is greater than projected rainfall changes in the SPCZ region. Using a hierarchy of climate models we show that the uncertainty of SPCZ rainfall projections in the Southwest Pacific can be explained as a result of two competing mechanisms. Higher tropical sea surface temperatures (SST) lead to an overall increase of atmospheric moisture and rainfall while weaker SST gradients dynamically shift the SPCZ northeastward (see illustration) and promote summer drying in areas of the Southwest Pacific, similar to the response to strong El Niño events. Based on a multi-model ensemble of 55 greenhouse warming experiments and for moderate tropical warming of 2-3°C we estimate a 5% decrease of SPCZ rainfall, although uncertainty exceeds ±30% among CGCMs. For stronger tropical warming, a tendency for a wetter SPCZ region is identified.; Illustration of the "warmest gets wetter" response to projected 21st century greenhouse warming. Green shading depicts observed (1982-2009) rainfall during DJF (contour interval: 2 mm/day; starting at 1 mm/day). Blue (red) contours depict warming less (more) than the tropical mean (42.5°N/S) 21st century multi-model trend (contour interval: 0.2°C; starting at ±0.1°C).

Assessing Climate Change in Early Warm Season and Impacts on Wildfire Potential in the Southwestern United States

NASA Astrophysics Data System (ADS)

Kafatos, M.; Kim, S. H.; Kim, J.; Nghiem, S. V.; Fujioka, F.; Myoung, B.

2016-12-01

Wildfires are an important concern in the Southwestern United States (SWUS) where the prevalent semi-arid to arid climate, vegetation types and hot and dry warm seasons challenge strategic fire management. Although they are part of the natural cycle related to the region's climate, significant growth of urban areas and expansion of the wildland-urban interface, have made wildfires a serious high-risk hazard. Previous studies also showed that the SWUS region is prone to frequent droughts due to large variations in wet season rainfall and has suffered from a number of severe wildfires in the recent decades. Despite the increasing trend in large wildfires, future wildfire risk assessment studies at regional scales for proactive adaptations are lacking. Our previous study revealed strong correlations between the North Atlantic Oscillation (NAO) and temperatures during March-June in SWUS. The abnormally warm and dry conditions in an NAO-positive spring, combined with reduced winter precipitation, can cause an early start of a fire season and extend it for several seasons, from late spring to fall. A strong interannual variation of the Keetch-Byram Drought Index (KBDI) during the early warm season was also found in the 35 year period 1979 - 2013 of the North American Regional Reanalysis (NARR) dataset. Thus, it is crucial to investigate the climate change impact that early warm season temperatures have on future wildfire danger potential. Our study reported here examines fine-resolution fire-weather variables for 2041-2070 projected in the North American Regional Climate Change Assessment Program (NARCCAP). The high-resolution climate data were obtained from multiple regional climate models (RCM) driven by multiple climate scenarios projected from multiple global climate models (GCMs) in conjunction with multiple greenhouse gas concentration pathways. The local wildfire potential in future climate is investigated using both the Keetch-Byram Drought Index (KBDI) and the

How does climate warming affect plant-pollinator interactions?

PubMed

Hegland, Stein Joar; Nielsen, Anders; Lázaro, Amparo; Bjerknes, Anne-Line; Totland, Ørjan

2009-02-01

Climate warming affects the phenology, local abundance and large-scale distribution of plants and pollinators. Despite this, there is still limited knowledge of how elevated temperatures affect plant-pollinator mutualisms and how changed availability of mutualistic partners influences the persistence of interacting species. Here we review the evidence of climate warming effects on plants and pollinators and discuss how their interactions may be affected by increased temperatures. The onset of flowering in plants and first appearance dates of pollinators in several cases appear to advance linearly in response to recent temperature increases. Phenological responses to climate warming may therefore occur at parallel magnitudes in plants and pollinators, although considerable variation in responses across species should be expected. Despite the overall similarities in responses, a few studies have shown that climate warming may generate temporal mismatches among the mutualistic partners. Mismatches in pollination interactions are still rarely explored and their demographic consequences are largely unknown. Studies on multi-species plant-pollinator assemblages indicate that the overall structure of pollination networks probably are robust against perturbations caused by climate warming. We suggest potential ways of studying warming-caused mismatches and their consequences for plant-pollinator interactions, and highlight the strengths and limitations of such approaches.

Soil microbial responses to climate warming in Northern Andean alpine ecosystems

NASA Astrophysics Data System (ADS)

Gallery, R. E.; Lasso, E.

2017-12-01

The historically cooler temperatures and waterlogged soils of tropical alpine grasslands (páramo) have resulted in low decomposition rates and a large buildup of organic matter, making páramo one of the most important carbon sinks in tropical biomes. The climatic factors that favored the carbon accumulation are changing, and as a result páramo could play a disproportionate role in driving climate feedbacks through increased carbon released from these large soil carbon stores. Open top chamber warming experiments were established in the Colombian Andes in 2016 to quantify the magnitude of climate change on carbon balance and identify microbial and plant traits that regulate these impacts. Two focal sites differ in mean annual temperature, precipitation, and plant community richness. Heterotrophic respiration (RH,) was measured from soil cores incubated at temperatures representing current and projected warming. The warming effect on RH was sensitive to soil moisture, which could reflect shifts in microbial community composition and/or extracellular enzyme production or efficiency as soils dry. Bacterial, archaeal, and fungal communities in ambient and warmed plots were measured through high-throughput amplicon sequencing of the 16S rRNA and ITS1 rRNA gene regions. Communities showed strong spatial structuring both within and among páramo, reflecting the topographic heterogeneity of these ecosystems. Significant differences in relative abundance of dominant microbial taxa between páramo could be largely explained by soil bulk density, water holding capacity, and non-vascular plant cover. Phototrophs common to anoxic soils (e.g., Rhodospirillaceae, Hyphomicrobiaceae) were abundant. Taxa within Euryarchaeota were recovered, suggesting methanogenesis potential. Exploration of the magnitude and temperature sensitivity of methane flux is needed in these seasonally anoxic soils whose dynamics could have significant implications for the global climate system.

Climate Variability and Dengue Fever in Warm and Humid Mexico

PubMed Central

Colón-González, Felipe J.; Lake, Iain R.; Bentham, Graham

2011-01-01

Multiple linear regression models were fitted to look for associations between changes in the incidence rate of dengue fever and climate variability in the warm and humid region of Mexico. Data were collected for 12 Mexican provinces over a 23-year period (January 1985 to December 2007). Our results show that the incidence rate or risk of infection is higher during El Niño events and in the warm and wet season. We provide evidence to show that dengue fever incidence was positively associated with the strength of El Niño and the minimum temperature, especially during the cool and dry season. Our study complements the understanding of dengue fever dynamics in the region and may be useful for the development of early warning systems. PMID:21540386

Biomass production in experimental grasslands of different species richness during three years of climate warming

NASA Astrophysics Data System (ADS)

de Boeck, H. J.; Lemmens, C. M. H. M.; Zavalloni, C.; Gielen, B.; Malchair, S.; Carnol, M.; Merckx, R.; van den Berge, J.; Ceulemans, R.; Nijs, I.

2008-04-01

Here we report on the single and combined impacts of climate warming and species richness on the biomass production in experimental grassland communities. Projections of a future warmer climate have stimulated studies on the response of terrestrial ecosystems to this global change. Experiments have likewise addressed the importance of species numbers for ecosystem functioning. There is, however, little knowledge on the interplay between warming and species richness. During three years, we grew experimental plant communities containing one, three or nine grassland species in 12 sunlit, climate-controlled chambers in Wilrijk, Belgium. Half of these chambers were exposed to ambient air temperatures (unheated), while the other half were warmed by 3°C (heated). Equal amounts of water were added to heated and unheated communities, so that warming would imply drier soils if evapotranspiration was higher. Biomass production was decreased due to warming, both aboveground (-29%) and belowground (-25%), as negative impacts of increased heat and drought stress in summer prevailed. Complementarity effects, likely mostly through both increased aboveground spatial complementarity and facilitative effects of legumes, led to higher shoot and root biomass in multi-species communities, regardless of the induced warming. Surprisingly, warming suppressed productivity the most in 9-species communities, which may be attributed to negative impacts of intense interspecific competition for resources under conditions of high abiotic stress. Our results suggest that warming and the associated soil drying could reduce primary production in many temperate grasslands, and that this will not necessarily be mitigated by efforts to maintain or increase species richness.

Analysing regional climate change in Africa in a 1.5 °C global warming world

NASA Astrophysics Data System (ADS)

Weber, Torsten; Haensler, Andreas; Jacob, Daniela

2017-04-01

At the 21st session of the UNFCCC Conference of the Parties (COP21) in Paris, a reaffirmation to strengthen the effort to limit the global temperature increase to 1.5 °C was decided. However, even if global warming is limited, some regions might still be substantially affected by climate change, especially for continents like Africa where the socio-economic conditions are strongly linked to the climatic conditions. Hence, providing a detailed analysis of the projected climate changes in a 1.5 °C global warming scenario will allow the African society to undertake measures for adaptation in order to mitigate potential negative consequences. In order to provide such climate change information, the existing CORDEX Africa ensemble for RCP2.6 scenario simulations has systematically been increased by conducting additional REMO simulations using data from various global circulation models (GCMs) as lateral boundary conditions. Based on this ensemble, which now consists of eleven CORDEX Africa RCP2.6 regional climate model simulations from three RCMs (forced with different GCMs), various temperature and precipitation indices such as number of cold/hot days and nights, duration of the rainy season, the amount of rainfall in the rainy seasons and the number of dry spells have been calculated for a 1.5 °C global warming scenario. The applied method to define the 1.5 °C global warming period has been already applied in the IMPACT2C project. In our presentation, we will discuss the analysis of the climate indices in a 1.5 °C global warming world for the CORDEX-Africa region. Amongst presenting the magnitude of projected changes, we will also address the question for selected indices if the changes projected in a 1.5 °C global warming scenario are already larger than the climate variability and we will also draw links to the changes projected under a more extreme scenario.

Detecting Climate Signals in Precipitation Extremes from TRMM (1998-2013) - Increasing Contrast Between Wet and Dry Extremes During the "Global Warming Hiatus"

NASA Technical Reports Server (NTRS)

Wu, Huey-Tzu Jenny; Lau, William K.-M.

2016-01-01

We investigate changes in daily precipitation extremes using Tropical Rainfall Measuring Mission (TRMM) data (1998-2013), which coincides with the "global warming hiatus." Results show a change in probability distribution functions of local precipitation events (LPEs) during this period consistent with previous global warming studies, indicating increasing contrast between wet and dry extremes, with more intense LPE, less moderate LPE, and more dry (no rain) days globally. Analyses for land and ocean separately reveal more complex and nuanced changes over land, characterized by a strong positive trend (+12.0% per decade, 99% confidence level (c.l.)) in frequency of extreme LPEs over the Northern Hemisphere extratropics during the wet season but a negative global trend (-6.6% per decade, 95% c.l.) during the dry season. A significant global drying trend (3.2% per decade, 99% c.l.) over land is also found during the dry season. Regions of pronounced increased dry events include western and central U.S., northeastern Asia, and Southern Europe/Mediterranean.

Anthropogenic warming has increased drought risk in California.

PubMed

Diffenbaugh, Noah S; Swain, Daniel L; Touma, Danielle

2015-03-31

California is currently in the midst of a record-setting drought. The drought began in 2012 and now includes the lowest calendar-year and 12-mo precipitation, the highest annual temperature, and the most extreme drought indicators on record. The extremely warm and dry conditions have led to acute water shortages, groundwater overdraft, critically low streamflow, and enhanced wildfire risk. Analyzing historical climate observations from California, we find that precipitation deficits in California were more than twice as likely to yield drought years if they occurred when conditions were warm. We find that although there has not been a substantial change in the probability of either negative or moderately negative precipitation anomalies in recent decades, the occurrence of drought years has been greater in the past two decades than in the preceding century. In addition, the probability that precipitation deficits co-occur with warm conditions and the probability that precipitation deficits produce drought have both increased. Climate model experiments with and without anthropogenic forcings reveal that human activities have increased the probability that dry precipitation years are also warm. Further, a large ensemble of climate model realizations reveals that additional global warming over the next few decades is very likely to create ∼ 100% probability that any annual-scale dry period is also extremely warm. We therefore conclude that anthropogenic warming is increasing the probability of co-occurring warm-dry conditions like those that have created the acute human and ecosystem impacts associated with the "exceptional" 2012-2014 drought in California.

Prolonged California aridity linked to climate warming and Pacific sea surface temperature.

PubMed

MacDonald, Glen M; Moser, Katrina A; Bloom, Amy M; Potito, Aaron P; Porinchu, David F; Holmquist, James R; Hughes, Julia; Kremenetski, Konstantine V

2016-09-15

California has experienced a dry 21(st) century capped by severe drought from 2012 through 2015 prompting questions about hydroclimatic sensitivity to anthropogenic climate change and implications for the future. We address these questions using a Holocene lake sediment record of hydrologic change from the Sierra Nevada Mountains coupled with marine sediment records from the Pacific. These data provide evidence of a persistent relationship between past climate warming, Pacific sea surface temperature (SST) shifts and centennial to millennial episodes of California aridity. The link is most evident during the thermal-maximum of the mid-Holocene (~8 to 3 ka; ka = 1,000 calendar years before present) and during the Medieval Climate Anomaly (MCA) (~1 ka to 0.7 ka). In both cases, climate warming corresponded with cooling of the eastern tropical Pacific despite differences in the factors producing increased radiative forcing. The magnitude of prolonged eastern Pacific cooling was modest, similar to observed La Niña excursions of 1(o) to 2 °C. Given differences with current radiative forcing it remains uncertain if the Pacific will react in a similar manner in the 21st century, but should it follow apparent past behavior more intense and prolonged aridity in California would result.

Abrupt climate warming in East Antarctica during the early Holocene

NASA Astrophysics Data System (ADS)

Cremer, Holger; Heiri, Oliver; Wagner, Bernd; Wagner-Cremer, Friederike

2007-08-01

We report a centennial-scale warming event between 8600 and 8400 cal BP from Amery Oasis, East Antarctica, that is documented by the geochemical record in a lacustrine sediment sequence. The organic carbon content, the C/S ratio, and the sedimentation rate in this core have distinctly elevated values around 8500 y ago reflecting relatively warm and ice-free conditions that led to well-ventilated conditions in the lake and considerable sedimentation of both autochthonous and allochthonous organic matter on the lake bottom. This abrupt warming event occurred concurrently with reported warm climatic conditions in the Southern Ocean while the climate in central East Antarctic remained cold. The comparison of the spatial and temporal variability of warm climatic periods documented in various terrestrial, marine, and glacial archives from East Antarctica elucidates the uniqueness of the centennial-scale warming event in the Amery Oasis. We also discuss a possible correlation of the Amery warming event with the abrupt climatic deterioration around 8200 cal BP on the Northern Hemisphere.

Assessment of long-term monthly and seasonal trends of warm (cold), wet (dry) spells in Kansas, USA

NASA Astrophysics Data System (ADS)

Dokoohaki, H.; Anandhi, A.

2013-12-01

A few recent studies have focused on trends in rainfall, temperature, and frost indicators at different temporal scales using centennial weather station data in Kansas; our study supplements this work by assessing the changes in spell indicators in Kansas. These indicators provide the duration between temperature-based (warm and cold) and precipitation-based (wet and dry) spells. For wet (dry) spell calculations, a wet day is defined as a day with precipitation ≥1 mm, and a dry day is defined as one with precipitation ≤1 mm. For warm (cold) spell calculations, a warm day is defined as a day with maximum temperature >90th percentile of daily maximum temperature, and a cold day is defined as a day with minimum temperature <10th percentile of daily minimum temperature. The percentiles are calculated for 1971-2000, and four spell indicators are calculated: Average Wet Spell Length (AWSL), Dry Spell Length (ADSL), Average Warm Spell Days (AWSD) and Average Cold Spell Days (ACSD) are calculated. Data were provided from 23 centennial weather stations across Kansas, and all calculations were done for four time periods (through 1919, 1920-1949, 1950-1979, and 1980-2009). The definitions and software provided by Expert Team on Climate Change Detection and Indices (ETCCDI) were adapted for application to Kansas. The long- and short-term trends in these indices were analyzed at monthly and seasonal timescales. Monthly results indicate that ADSL is decreasing and AWSL is increasing throughout the state. AWSD and ACSD both showed an overall decreasing trend, but AWSD trends were variable during the beginning of the Industrial Revolution. Results of seasonal analysis revealed that the fall season recorded the greatest increasing trend for ACSD and the greatest decreasing trend for AWSD across the whole state and during all time periods. Similarly, the greatest increasing and decreasing trends occurred in winter for AWSL and ADSL, respectively. These variations can be

Can climate-effective land management reduce regional warming?

NASA Astrophysics Data System (ADS)

Hirsch, A. L.; Wilhelm, M.; Davin, E. L.; Thiery, W.; Seneviratne, S. I.

2017-02-01

Limiting global warming to well below 2°C is an imminent challenge for humanity. However, even if this global target can be met, some regions are still likely to experience substantial warming relative to others. Using idealized global climate simulations, we examine the potential of land management options in affecting regional climate, with a focus on crop albedo enhancement and irrigation (climate-effective land management). The implementation is performed over all crop regions globally to provide an upper bound. We find that the implementation of both crop albedo enhancement and irrigation can reduce hot temperature extremes by more than 2°C in North America, Eurasia, and India over the 21st century relative to a scenario without management application. The efficacy of crop albedo enhancement scales with the magnitude, where a cooling response exceeding 0.5°C for hot temperature extremes was achieved with a large (i.e., ≥0.08) change in crop albedo. Regional differences were attributed to the surface energy balance response with temperature changes mostly explained by latent heat flux changes for irrigation and net shortwave radiation changes for crop albedo enhancement. However, limitations do exist, where we identify warming over the winter months when climate-effective land management is temporarily suspended. This was associated with persistent cloud cover that enhances longwave warming. It cannot be confirmed if the magnitude of this feedback is reproducible in other climate models. Our results overall demonstrate that regional warming of hot extremes in our climate model can be partially mitigated when using an idealized treatment of climate-effective land management.

Anthropogenic warming has increased drought risk in California

PubMed Central

Diffenbaugh, Noah S.; Swain, Daniel L.; Touma, Danielle

2015-01-01

California is currently in the midst of a record-setting drought. The drought began in 2012 and now includes the lowest calendar-year and 12-mo precipitation, the highest annual temperature, and the most extreme drought indicators on record. The extremely warm and dry conditions have led to acute water shortages, groundwater overdraft, critically low streamflow, and enhanced wildfire risk. Analyzing historical climate observations from California, we find that precipitation deficits in California were more than twice as likely to yield drought years if they occurred when conditions were warm. We find that although there has not been a substantial change in the probability of either negative or moderately negative precipitation anomalies in recent decades, the occurrence of drought years has been greater in the past two decades than in the preceding century. In addition, the probability that precipitation deficits co-occur with warm conditions and the probability that precipitation deficits produce drought have both increased. Climate model experiments with and without anthropogenic forcings reveal that human activities have increased the probability that dry precipitation years are also warm. Further, a large ensemble of climate model realizations reveals that additional global warming over the next few decades is very likely to create ∼100% probability that any annual-scale dry period is also extremely warm. We therefore conclude that anthropogenic warming is increasing the probability of co-occurring warm–dry conditions like those that have created the acute human and ecosystem impacts associated with the “exceptional” 2012–2014 drought in California. PMID:25733875

Terrestrial carbon cycle affected by non-uniform climate warming

NASA Astrophysics Data System (ADS)

Xia, Jianyang; Chen, Jiquan; Piao, Shilong; Ciais, Philippe; Luo, Yiqi; Wan, Shiqiang

2014-03-01

Feedbacks between the terrestrial carbon cycle and climate change could affect many ecosystem functions and services, such as food production, carbon sequestration and climate regulation. The rate of climate warming varies on diurnal and seasonal timescales. A synthesis of global air temperature data reveals a greater rate of warming in winter than in summer in northern mid and high latitudes, and the inverse pattern in some tropical regions. The data also reveal a decline in the diurnal temperature range over 51% of the global land area and an increase over only 13%, because night-time temperatures in most locations have risen faster than daytime temperatures. Analyses of satellite data, model simulations and in situ observations suggest that the impact of seasonal warming varies between regions. For example, spring warming has largely stimulated ecosystem productivity at latitudes between 30° and 90° N, but suppressed productivity in other regions. Contrasting impacts of day- and night-time warming on plant carbon gain and loss are apparent in many regions. We argue that ascertaining the effects of non-uniform climate warming on terrestrial ecosystems is a key challenge in carbon cycle research.

Global warming /climate change: Involving students using local example.

NASA Astrophysics Data System (ADS)

Isiorho, S. A.

2016-12-01

The current political climate has made it apparent that the general public does not believe in global warming. Also, there appears to be some confusion between global warming and climate change; global warming is one aspect of climate change. Most scientists believe there is climate change and global warming, although, there is still doubt among students on global warming. Some upper level undergraduate students are required to conduct water level/temperature measurements as part of their course grade. In addition to students having their individual projects, the various classes also utilize a well field within a wetland on campus to conduct group projects. Twelve wells in the well field on campus are used regularly by students to measure the depth of groundwater, the temperature of the waters and other basic water chemistry parameters like pH, conductivity and total dissolved solid (TDS) as part of the class group project. The data collected by each class is added to data from previous classes. Students work together as a group to interpret the data. More than 100 students have participated in this venture for more than 10 years of the four upper level courses: hydrogeology, environmental and urban geology, environmental conservation and wetlands. The temperature trend shows the seasonal variation as one would expect, but it also shows an upward trend (warming). These data demonstrate a change in climate and warming. Thus, the students participated in data collection, learn to write report and present their result to their peers in the classrooms.

Are Sierran Lakes Warming as a Result of Climate Change? The Effects of Climate Warming and Variation in Precipitation on Water Temperature in a Snowmelt-Dominated Lake

NASA Astrophysics Data System (ADS)

Sadro, S.; Melack, J. M.; Sickman, J. O.; Skeen, K.

2016-12-01

Water temperature regulates a broad range of fundamental ecosystem processes in lakes. While climate can be an important factor regulating lake temperatures, heterogeneity in the warming response of lakes is large, and variation in precipitation is rarely considered. We analyzed three decades of climate and water temperature data from a high-elevation catchment in the southern Sierra Nevada of California to illustrate the magnitude of warming taking place during different seasons and the role of precipitation in regulating lake temperatures. Significant climate warming trends were evident during all seasons except spring. Nighttime rates of climate warming were approximately 25% higher than daytime rates. Spatial patterns in warming were elevation dependent, with rates of temperature increase higher at sites above 2800 m.a.s.l. than below. Although interannual variation in snow deposition was high, the frequency and severity of recent droughts has contributed to a significant 3.4 mm year -1 decline in snow water equivalent over the last century. Snow accumulation, more than any other climate factor, regulated lake temperature; 94% of variation in summer lake temperature was regulated by precipitation as snow. For every 100 mm decrease in snow water equivalent there was a 0.62 ° increase in lake temperature. Drought years amplify warming in lakes by reducing the role of cold spring meltwaters in lake energy budgets and prolonging the ice-free period during which lakes warm. The combination of declining winter snowpack and warming air temperatures has the capacity to amplify the effect of climate warming on lake temperatures during drought years. Interactions among climatic factors need to be considered when evaluating ecosystem level effects, especially in mountain regions. For mountain lakes already affected by drought, continued climate warming during spring and autumn has the greatest potential to impact mean lake temperatures.

Potential impact of 1.5 °C and 2 °C global warming on consecutive dry and wet days over West Africa

NASA Astrophysics Data System (ADS)

Ama Browne Klutse, Nana; Ajayi, Vincent O.; Olabode Gbobaniyi, Emiola; Egbebiyi, Temitope S.; Kouadio, Kouakou; Nkrumah, Francis; Akumenyi Quagraine, Kwesi; Olusegun, Christiana; Diasso, Ulrich; Abiodun, Babatunde J.; Lawal, Kamoru; Nikulin, Grigory; Lennard, Christopher; Dosio, Alessandro

2018-05-01

We examine the impact of +1.5 °C and +2 °C global warming levels above pre-industrial levels on consecutive dry days (CDD) and consecutive wet days (CWD), two key indicators for extreme precipitation and seasonal drought. This is done using climate projections from a multi-model ensemble of 25 regional climate model (RCM) simulations. The RCMs take boundary conditions from ten global climate models (GCMs) under the RCP8.5 scenario. We define CDD as the maximum number of consecutive days with rainfall amount less than 1 mm and CWD as the maximum number of consecutive days with rainfall amount more than 1 mm. The differences in model representations of the change in CDD and CWD, at 1.5 °C and 2 °C global warming, and based on the control period 1971‑2000 are reported. The models agree on a noticeable response to both 1.5 °C and 2 °C warming for each index. Enhanced warming results in a reduction in mean rainfall across the region. More than 80% of ensemble members agree that CDD will increase over the Guinea Coast, in tandem with a projected decrease in CWD at both 1.5 °C and 2 °C global warming levels. These projected changes may influence already fragile ecosystems and agriculture in the region, both of which are strongly affected by mean rainfall and the length of wet and dry periods.

Global metabolic impacts of recent climate warming.

PubMed

Dillon, Michael E; Wang, George; Huey, Raymond B

2010-10-07

Documented shifts in geographical ranges, seasonal phenology, community interactions, genetics and extinctions have been attributed to recent global warming. Many such biotic shifts have been detected at mid- to high latitudes in the Northern Hemisphere-a latitudinal pattern that is expected because warming is fastest in these regions. In contrast, shifts in tropical regions are expected to be less marked because warming is less pronounced there. However, biotic impacts of warming are mediated through physiology, and metabolic rate, which is a fundamental measure of physiological activity and ecological impact, increases exponentially rather than linearly with temperature in ectotherms. Therefore, tropical ectotherms (with warm baseline temperatures) should experience larger absolute shifts in metabolic rate than the magnitude of tropical temperature change itself would suggest, but the impact of climate warming on metabolic rate has never been quantified on a global scale. Here we show that estimated changes in terrestrial metabolic rates in the tropics are large, are equivalent in magnitude to those in the north temperate-zone regions, and are in fact far greater than those in the Arctic, even though tropical temperature change has been relatively small. Because of temperature's nonlinear effects on metabolism, tropical organisms, which constitute much of Earth's biodiversity, should be profoundly affected by recent and projected climate warming.

State-dependent climate sensitivity in past warm climates and its implications for future climate projections.

PubMed

Caballero, Rodrigo; Huber, Matthew

2013-08-27

Projections of future climate depend critically on refined estimates of climate sensitivity. Recent progress in temperature proxies dramatically increases the magnitude of warming reconstructed from early Paleogene greenhouse climates and demands a close examination of the forcing and feedback mechanisms that maintained this warmth and the broad dynamic range that these paleoclimate records attest to. Here, we show that several complementary resolutions to these questions are possible in the context of model simulations using modern and early Paleogene configurations. We find that (i) changes in boundary conditions representative of slow "Earth system" feedbacks play an important role in maintaining elevated early Paleogene temperatures, (ii) radiative forcing by carbon dioxide deviates significantly from pure logarithmic behavior at concentrations relevant for simulation of the early Paleogene, and (iii) fast or "Charney" climate sensitivity in this model increases sharply as the climate warms. Thus, increased forcing and increased slow and fast sensitivity can all play a substantial role in maintaining early Paleogene warmth. This poses an equifinality problem: The same climate can be maintained by a different mix of these ingredients; however, at present, the mix cannot be constrained directly from climate proxy data. The implications of strongly state-dependent fast sensitivity reach far beyond the early Paleogene. The study of past warm climates may not narrow uncertainty in future climate projections in coming centuries because fast climate sensitivity may itself be state-dependent, but proxies and models are both consistent with significant increases in fast sensitivity with increasing temperature.

Why were Past North Atlantic Warming Conditions Associated with Drier Climate in the Western United States?

NASA Astrophysics Data System (ADS)

Wong, C. I.; Potter, G. L.; Montanez, I. P.; Otto-Bliesner, B. L.; Behling, P.; Oster, J. L.

2014-12-01

Investigating climate dynamics governing rainfall over the western US during past warmings and coolings of the last glacial and deglaciation is pertinent to understanding how precipitation patterns might change with future global warming, especially as the processes driving the global hydrological reorganization affecting this drought-prone region during these rapid temperature changes remain unresolved. We present model climates of the Bølling warm event (14,500 years ago) and Younger Dryas cool event (12,200 years ago) that i) uniquely enable the assessment of dueling hypothesis about the atmospheric teleconnections responsible for abrupt temperature shifts in the North Atlantic region to variations in moisture conditions across the western US, and ii) show that existing hypotheses about these teleconnections are unsupported. Modeling results show no evidence for a north-south shift of the Pacific winter storm track, and we argue that a tropical moisture source with evolving trajectory cannot explain alternation between wet/dry conditions, which have been reconstructed from the proxy record. Alternatively, model results support a new hypothesis that variations in the intensity of the winter storm track, corresponding to its expansion/contraction, can account for regional moisture differences between warm and cool intervals of the last deglaciation. Furthermore, we demonstrate that the mechanism forcing the teleconnection between the North Atlantic and western US is the same across different boundary conditions. In our simulation, during the last deglaciation, and in simulations of future warming, perturbation of the Rossby wave structure reconfigures the atmospheric state. This reconfiguration affects the Aleutian Low and high-pressure ridge over and off of the northern North American coastline driving variability in the storm track. Similarity between the processes governing the climate response during these distinct time intervals illustrates the robust nature

Climate warming drives local extinction: Evidence from observation and experimentation.

PubMed

Panetta, Anne Marie; Stanton, Maureen L; Harte, John

2018-02-01

Despite increasing concern about elevated extinction risk as global temperatures rise, it is difficult to confirm causal links between climate change and extinction. By coupling 25 years of in situ climate manipulation with experimental seed introductions and both historical and current plant surveys, we identify causal, mechanistic links between climate change and the local extinction of a widespread mountain plant ( Androsace septentrionalis ). Climate warming causes precipitous declines in population size by reducing fecundity and survival across multiple life stages. Climate warming also purges belowground seed banks, limiting the potential for the future recovery of at-risk populations under ameliorated conditions. Bolstered by previous reports of plant community shifts in this experiment and in other habitats, our findings not only support the hypothesis that climate change can drive local extinction but also foreshadow potentially widespread species losses in subalpine meadows as climate warming continues.

Climate Warming Threatens Semi-arid Forests in Inner Asia

NASA Astrophysics Data System (ADS)

WU, X.; Liu, H.; Qi, Z.; Li, X.

2014-12-01

A line of evidences reveal an increasing tree growth decline and tree mortality mainly attributable to climate warming and the warming-mediated changes in drought and other processes (such as fire and insect dynamics) in many parts of world tropical, temperate and boreal forests. However, the growth responses to climate change of the widely distributed semi-arid forests are unclear. Here, we synthetically investigate the tree growth patterns during past decades and its interannual response to climate variations in Inner Asia combining the ground truth field survey and samplings, remote sensing observations and climate data. We identified a pervasive tree growth decline since mid-1990s in semi-arid forests in Inner Asia. The widely observed tree growth decline is dominantly attributable to warming-induced water stress during pre- and early growing season. Tree growth of semi-arid forests in Inner Asia is particularly susceptible to spring warming and has been suffering a prolonged growth limitation in recent decades due to spring warming-mediated water conditions. Additionally, we identified a much slower growth rate in younger trees and a lack of tree regeneration in these semi-arid forests. The widely observed forest growth reduction and lack of tree regeneration over semi-arid forests in Inner Asia could predictably exert great effects on forest structure, regionally/globally biophysical and biochemical processes and the feedbacks between biosphere and atmosphere. Notably, further increases in forest stress and tree mortality could be reasonably expected, especially in context of the increase frequency and severity of high temperature and heat waves and changes in forest disturbances, potentially driving the eventual regional loss of current semi-arid forests. Given the potential risks of climate induced forest dieback, increased management attention to adaptation options for enhancing forest resistance and resilience to projected climate stress can be expected

Climate warming, euxinia and carbon isotope perturbations during the Carnian (Triassic) Crisis in South China

NASA Astrophysics Data System (ADS)

Sun, Y. D.; Wignall, P. B.; Joachimski, M. M.; Bond, D. P. G.; Grasby, S. E.; Lai, X. L.; Wang, L. N.; Zhang, Z. T.; Sun, S.

2016-06-01

The Carnian Humid Episode (CHE), also known as the Carnian Pluvial Event, and associated biotic changes are major enigmas of the Mesozoic record in western Tethys. We show that the CHE also occurred in eastern Tethys (South China), suggestive of a much more widespread and probably global climate perturbation. Oxygen isotope records from conodont apatite indicate a double-pulse warming event. The CHE coincided with an initial warming of 4 °C. This was followed by a transient cooling period and then a prolonged ∼7 °C warming in the later Carnian (Tuvalian 2). Carbon isotope perturbations associated with the CHE of western Tethys occurred contemporaneously in South China, and mark the start of a prolonged period of carbon cycle instability that persisted until the late Carnian. The dry-wet transition during the CHE coincides with the negative carbon isotope excursion and the temperature rise, pointing to an intensification of hydrologic cycle activities due to climatic warming. While carbonate platform shutdown in western Tethys is associated with an influx of siliciclastic sediment, the eastern Tethyan carbonate platforms are overlain by deep-water anoxic facies. The transition from oxygenated to euxinic facies was via a condensed, manganiferous carbonate (MnO content up to 15.1 wt%), that records an intense Mn shuttle operating in the basin. Significant siliciclastic influx in South China only occurred after the CHE climatic changes and was probably due to foreland basin development at the onset of the Indosinian Orogeny. The mid-Carnian biotic crisis thus coincided with several phenomena associated with major extinction events: a carbonate production crisis, climate warming, δ13 C oscillations, marine anoxia, biotic turnover and flood basalt eruptions (of the Wrangellia Large Igneous Province).

State-dependent climate sensitivity in past warm climates and its implications for future climate projections

PubMed Central

Caballero, Rodrigo; Huber, Matthew

2013-01-01

Projections of future climate depend critically on refined estimates of climate sensitivity. Recent progress in temperature proxies dramatically increases the magnitude of warming reconstructed from early Paleogene greenhouse climates and demands a close examination of the forcing and feedback mechanisms that maintained this warmth and the broad dynamic range that these paleoclimate records attest to. Here, we show that several complementary resolutions to these questions are possible in the context of model simulations using modern and early Paleogene configurations. We find that (i) changes in boundary conditions representative of slow “Earth system” feedbacks play an important role in maintaining elevated early Paleogene temperatures, (ii) radiative forcing by carbon dioxide deviates significantly from pure logarithmic behavior at concentrations relevant for simulation of the early Paleogene, and (iii) fast or “Charney” climate sensitivity in this model increases sharply as the climate warms. Thus, increased forcing and increased slow and fast sensitivity can all play a substantial role in maintaining early Paleogene warmth. This poses an equifinality problem: The same climate can be maintained by a different mix of these ingredients; however, at present, the mix cannot be constrained directly from climate proxy data. The implications of strongly state-dependent fast sensitivity reach far beyond the early Paleogene. The study of past warm climates may not narrow uncertainty in future climate projections in coming centuries because fast climate sensitivity may itself be state-dependent, but proxies and models are both consistent with significant increases in fast sensitivity with increasing temperature. PMID:23918397

Climate warming drives local extinction: Evidence from observation and experimentation

PubMed Central

Panetta, Anne Marie; Stanton, Maureen L.; Harte, John

2018-01-01

Despite increasing concern about elevated extinction risk as global temperatures rise, it is difficult to confirm causal links between climate change and extinction. By coupling 25 years of in situ climate manipulation with experimental seed introductions and both historical and current plant surveys, we identify causal, mechanistic links between climate change and the local extinction of a widespread mountain plant (Androsace septentrionalis). Climate warming causes precipitous declines in population size by reducing fecundity and survival across multiple life stages. Climate warming also purges belowground seed banks, limiting the potential for the future recovery of at-risk populations under ameliorated conditions. Bolstered by previous reports of plant community shifts in this experiment and in other habitats, our findings not only support the hypothesis that climate change can drive local extinction but also foreshadow potentially widespread species losses in subalpine meadows as climate warming continues. PMID:29507884

Effects of in situ climate warming on monarch caterpillar (Danaus plexippus) development.

PubMed

Lemoine, Nathan P; Capdevielle, Jillian N; Parker, John D

2015-01-01

Climate warming will fundamentally alter basic life history strategies of many ectothermic insects. In the lab, rising temperatures increase growth rates of lepidopteran larvae but also reduce final pupal mass and increase mortality. Using in situ field warming experiments on their natural host plants, we assessed the impact of climate warming on development of monarch (Danaus plexippus) larvae. Monarchs were reared on Asclepias tuberosa grown under 'Ambient' and 'Warmed' conditions. We quantified time to pupation, final pupal mass, and survivorship. Warming significantly decreased time to pupation, such that an increase of 1 °C corresponded to a 0.5 day decrease in pupation time. In contrast, survivorship and pupal mass were not affected by warming. Our results indicate that climate warming will speed the developmental rate of monarchs, influencing their ecological and evolutionary dynamics. However, the effects of climate warming on larval development in other monarch populations and at different times of year should be investigated.

Tropical Indian Ocean warming contributions to China winter climate trends since 1960

NASA Astrophysics Data System (ADS)

Wu, Qigang; Yao, Yonghong; Liu, Shizuo; Cao, DanDan; Cheng, Luyao; Hu, Haibo; Sun, Leng; Yao, Ying; Yang, Zhiqi; Gao, Xuxu; Schroeder, Steven R.

2018-01-01

This study investigates observed and modeled contributions of global sea surface temperature (SST) to China winter climate trends in 1960-2014, including increased precipitation, warming through about 1997, and cooling since then. Observations and Atmospheric Model Intercomparison Project (AMIP) simulations with prescribed historical SST and sea ice show that tropical Indian Ocean (TIO) warming and increasing rainfall causes diabatic heating that generates a tropospheric wave train with anticyclonic 500-hPa height anomaly centers in the TIO or equatorial western Pacific (TIWP) and northeastern Eurasia (EA) and a cyclonic anomaly over China, referred to as the TIWP-EA wave train. The cyclonic anomaly causes Indochina moisture convergence and southwesterly moist flow that enhances South China precipitation, while the northern anticyclone enhances cold surges, sometimes causing severe ice storms. AMIP simulations show a 1960-1997 China cooling trend by simulating increasing instead of decreasing Arctic 500-hPa heights that move the northern anticyclone into Siberia, but enlarge the cyclonic anomaly so it still simulates realistic China precipitation trend patterns. A separate idealized TIO SST warming simulation simulates the TIWP-EA feature more realistically with correct precipitation patterns and supports the TIWP-EA teleconnection as the primary mechanism for long-term increasing precipitation in South China since 1960. Coupled Model Intercomparison Project (CMIP) experiments simulate a reduced TIO SST warming trend and weak precipitation trends, so the TIWP-EA feature is absent and strong drying is simulated in South China for 1960-1997. These simulations highlight the need for accurately modeled SST to correctly attribute regional climate trends.

Contrasting responses of shrubland carbon gain and soil carbon efflux to drought and warming across a European climate gradient

NASA Astrophysics Data System (ADS)

Reinsch, Sabine; Koller, Eva; Sowerby, Alwyn; de Dato, Giovanbattista; Estiarte, Marc; Guidolotti, Gabriele; Kovács-Láng, Edit; Kröel-Dulay, György; Lellei-Kovács, Eszter; Larsen, Klaus S.; Liberati, Dario; Penuelas, Josep; Ransijn, Johannes; Schmidt, Inger K.; Smith, Andrew R.; Tietema, Albert; Dukes, Jeffrey S.; Emmett, Bridget A.

2016-04-01

Understanding the relationship between above- and belowground processes is crucial if we are to forecast feedbacks between terrestrial carbon (C) dynamics and future climate. To test if climate-induced changes in annual aboveground net primary productivity (aNPP) will drive changes in C loss by soil respiration (Rs), we integrated data across a European temperature and precipitation gradient. For over a decade, six European shrublands were exposed to repeated drought (-30 % annual rain) during the plants' growth season or year-round night-time warming (+1.5 oC), using an identical experimental approach. As a result, drought reduced ecosystem C gain via aNPP by 0-25 % (compared to an untreated control) with the lowest C gain in warm-dry sites and highest in wet-cold sites (R2=0.078, p-value = 0.544, slope = 14.35 %). In contrast, drought induced C loss via Rs was of a lower magnitude (10-20 %) and was most pronounced in warm-dry sites compared to wet-cold sites (R2=0.687, p-value = 0.131, slope = 7.86 %). This suggests that belowground activity (microbes and roots) is stabilizing ecosystem processes and functions in terms of C storage. However, when the drought treatment permanently altered the soil structure at our hydric site, indicating we had exceeded the resilience of the system, the ecosystem C gain was no longer predictable from current (linear) relationships. Results from the warming treatment were generally of lower magnitude and of opposing direction compared to the drought treatment, indicating different mechanisms were driving ecosystem responses. Overall, our results suggest that aNPP is less sensitive than Rs to climate stresses and soil respiration C fluxes are not predictable from changes in plant productivity. Drought and warming effects on aNPP and Rs did not weaken over decadal timescales at larger, continental scales if no catastrophic threshold is passed. However, indirect effects of climate change on soil properties and/or microbial communities

Climatic warming and the future of bison as grazers

NASA Astrophysics Data System (ADS)

Craine, Joseph M.; Towne, E. Gene; Miller, Mary; Fierer, Noah

2015-11-01

Climatic warming is likely to exacerbate nutritional stress and reduce weight gain in large mammalian herbivores by reducing plant nutritional quality. Yet accurate predictions of the effects of climatic warming on herbivores are limited by a poor understanding of how herbivore diet varies along climate gradients. We utilized DNA metabarcoding to reconstruct seasonal variation in the diet of North American bison (Bison bison) in two grasslands that differ in mean annual temperature by 6 °C. Here, we show that associated with greater nutritional stress in warmer climates, bison consistently consumed fewer graminoids and more shrubs and forbs, i.e. eudicots. Bison in the warmer grassland consumed a lower proportion of C3 grass, but not a greater proportion of C4 grass. Instead, bison diet in the warmer grassland had a greater proportion of N2-fixing eudicots, regularly comprising >60% of their protein intake in spring and fall. Although bison have been considered strict grazers, as climatic warming reduces grass protein concentrations, bison may have to attempt to compensate by grazing less and browsing more. Promotion of high-protein, palatable eudicots or increasing the protein concentrations of grasses will be critical to minimizing warming-imposed nutritional stress for bison and perhaps other large mammalian herbivores.

Future vegetation ecosystem response to warming climate over the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Bao, Y.; Gao, Y.; Wang, Y.

2017-12-01

The amplified vegetation response to climate variability has been found over the Tibetan Plateau (TP) in recent decades. In this study, the potential impacts of 21st century climate change on the vegetation ecosystem over the TP are assessed based on the dynamic vegetation outputs of models from Coupled Model Intercomparison Project Phase 5 (CMIP5), and the sensitivity of the TP vegetation in response to warming climate was investigated. Models project a continuous and accelerating greening in future, especially in the eastern TP, which closely associates with the plant type upgrade due to the pronouncing warming in growing season.Vegetation leaf area index (LAI) increase well follows the global warming, suggesting the warming climate instead of co2 fertilization controlls the future TP plant growth. The warming spring may advance the start of green-up day and extend the growing season length. More carbon accumulation in vegetation and soil will intensify the TP carbon cycle and will keep it as a carbon sink in future. Keywords: Leaf Area Index (LAI), Climate Change, Global Dynamic Vegetation Models (DGVMs), CMIP5, Tibetan Plateau (TP)

Why tropical forest lizards are vulnerable to climate warming.

PubMed

Huey, Raymond B; Deutsch, Curtis A; Tewksbury, Joshua J; Vitt, Laurie J; Hertz, Paul E; Alvarez Pérez, Héctor J; Garland, Theodore

2009-06-07

Biological impacts of climate warming are predicted to increase with latitude, paralleling increases in warming. However, the magnitude of impacts depends not only on the degree of warming but also on the number of species at risk, their physiological sensitivity to warming and their options for behavioural and physiological compensation. Lizards are useful for evaluating risks of warming because their thermal biology is well studied. We conducted macrophysiological analyses of diurnal lizards from diverse latitudes plus focal species analyses of Puerto Rican Anolis and Sphaerodactyus. Although tropical lowland lizards live in environments that are warm all year, macrophysiological analyses indicate that some tropical lineages (thermoconformers that live in forests) are active at low body temperature and are intolerant of warm temperatures. Focal species analyses show that some tropical forest lizards were already experiencing stressful body temperatures in summer when studied several decades ago. Simulations suggest that warming will not only further depress their physiological performance in summer, but will also enable warm-adapted, open-habitat competitors and predators to invade forests. Forest lizards are key components of tropical ecosystems, but appear vulnerable to the cascading physiological and ecological effects of climate warming, even though rates of tropical warming may be relatively low.

Why tropical forest lizards are vulnerable to climate warming

PubMed Central

Huey, Raymond B.; Deutsch, Curtis A.; Tewksbury, Joshua J.; Vitt, Laurie J.; Hertz, Paul E.; Álvarez Pérez, Héctor J.; Garland, Theodore

2009-01-01

Biological impacts of climate warming are predicted to increase with latitude, paralleling increases in warming. However, the magnitude of impacts depends not only on the degree of warming but also on the number of species at risk, their physiological sensitivity to warming and their options for behavioural and physiological compensation. Lizards are useful for evaluating risks of warming because their thermal biology is well studied. We conducted macrophysiological analyses of diurnal lizards from diverse latitudes plus focal species analyses of Puerto Rican Anolis and Sphaerodactyus. Although tropical lowland lizards live in environments that are warm all year, macrophysiological analyses indicate that some tropical lineages (thermoconformers that live in forests) are active at low body temperature and are intolerant of warm temperatures. Focal species analyses show that some tropical forest lizards were already experiencing stressful body temperatures in summer when studied several decades ago. Simulations suggest that warming will not only further depress their physiological performance in summer, but will also enable warm-adapted, open-habitat competitors and predators to invade forests. Forest lizards are key components of tropical ecosystems, but appear vulnerable to the cascading physiological and ecological effects of climate warming, even though rates of tropical warming may be relatively low. PMID:19324762

Changes in ENSO amplitude under climate warming and cooling

NASA Astrophysics Data System (ADS)

Wang, Yingying; Luo, Yiyong; Lu, Jian; Liu, Fukai

2018-05-01

The response of ENSO amplitude to climate warming and cooling is investigated using the Community Earth System Model (CESM), in which the warming and cooling scenarios are designed by adding heat fluxes of equal amplitude but opposite sign onto the ocean surface, respectively. Results show that the warming induces an increase of the ENSO amplitude but the cooling gives rise to a decrease of the ENSO amplitude, and these changes are robust in statistics. A mixed layer heat budget analysis finds that the increasing (decreasing) SST tendency under climate warming (cooling) is mainly due to an enhancement (weakening) of dynamical feedback processes over the equatorial Pacific, including zonal advective (ZA) feedback, meridional advective (MA) feedback, thermocline (TH) feedback, and Ekman (EK) feedback. As the climate warms, a wind anomaly of the same magnitude across the equatorial Pacific can induce a stronger zonal current change in the east (i.e., a stronger ZA feedback), which in turn produces a greater weakening of upwelling (i.e., a stronger EK feedback) and thus a larger thermocline change (i.e., a stronger TH feedback). In response to the climate warming, in addition, the MA feedback is also strengthened due to an enhancement of the meridional SST gradient around the equator resulting from a weakening of the subtropical cells (STCs). It should be noted that the weakened STCs itself has a negative contribution to the change of the MA feedback which, however, appears to be secondary. And vice versa for the cooling case. Bjerknes linear stability (BJ) index is also evaluated for the linear stability of ENSO, with remarkably larger (smaller) BJ index found for the warming (cooling) case.

Indian Ocean warming modulates Pacific climate change.

PubMed

Luo, Jing-Jia; Sasaki, Wataru; Masumoto, Yukio

2012-11-13

It has been widely believed that the tropical Pacific trade winds weakened in the last century and would further decrease under a warmer climate in the 21st century. Recent high-quality observations, however, suggest that the tropical Pacific winds have actually strengthened in the past two decades. Precise causes of the recent Pacific climate shift are uncertain. Here we explore how the enhanced tropical Indian Ocean warming in recent decades favors stronger trade winds in the western Pacific via the atmosphere and hence is likely to have contributed to the La Niña-like state (with enhanced east-west Walker circulation) through the Pacific ocean-atmosphere interactions. Further analysis, based on 163 climate model simulations with centennial historical and projected external radiative forcing, suggests that the Indian Ocean warming relative to the Pacific's could play an important role in modulating the Pacific climate changes in the 20th and 21st centuries.

Phenological sequences reveal aggregate life history response to climatic warming.

PubMed

Post, Eric S; Pedersen, Christian; Wilmers, Christopher C; Forchhammer, Mads C

2008-02-01

Climatic warming is associated with organisms breeding earlier in the season than is typical for their species. In some species, however, response to warming is more complex than a simple advance in the timing of all life history events preceding reproduction. Disparities in the extent to which different components of the reproductive phenology of organisms vary with climatic warming indicate that not all life history events are equally responsive to environmental variation. Here, we propose that our understanding of phenological response to climate change can be improved by considering entire sequences of events comprising the aggregate life histories of organisms preceding reproduction. We present results of a two-year warming experiment conducted on 33 individuals of three plant species inhabiting a low-arctic site. Analysis of phenological sequences of three key events for each species revealed how the aggregate life histories preceding reproduction responded to warming, and which individual events exerted the greatest influence on aggregate life history variation. For alpine chickweed (Cerastium alpinum), warming elicited a shortening of the duration of the emergence stage by 2.5 days on average, but the aggregate life history did not differ between warmed and ambient plots. For gray willow (Salix glauca), however, all phenological events monitored occurred earlier on warmed than on ambient plots, and warming reduced the aggregate life history of this species by 22 days on average. Similarly, in dwarf birch (Betula nana), warming advanced flower bud set, blooming, and fruit set and reduced the aggregate life history by 27 days on average. Our approach provides important insight into life history responses of many organisms to climate change and other forms of environmental variation. Such insight may be compromised by considering changes in individual phenological events in isolation.

Detecting urban warming signals in climate records

NASA Astrophysics Data System (ADS)

He, Yuting; Jia, Gensuo; Hu, Yonghong; Zhou, Zijiang

2013-07-01

Determining whether air temperatures recorded at meteorological stations have been contaminated by the urbanization process is still a controversial issue at the global scale. With support of historical remote sensing data, this study examined the impacts of urban expansion on the trends of air temperature at 69 meteorological stations in Beijing, Tianjin, and Hebei Province over the last three decades. There were significant positive relations between the two factors at all stations. Stronger warming was detected at the meteorological stations that experienced greater urbanization, i.e., those with a higher urbanization rate. While the total urban area affects the absolute temperature values, the change of the urban area (urbanization rate) likely affects the temperature trend. Increases of approximately 10% in urban area around the meteorological stations likely contributed to the 0.13°C rise in air temperature records in addition to regional climate warming. This study also provides a new approach to selecting reference stations based on remotely sensed urban fractions. Generally, the urbanization-induced warming contributed to approximately 44.1% of the overall warming trends in the plain region of study area during the past 30 years, and the regional climate warming was 0.30°C (10 yr)-1 in the last three decades.

Response of ocean ecosystems to climate warming

NASA Astrophysics Data System (ADS)

Sarmiento, J. L.; Slater, R.; Barber, R.; Bopp, L.; Doney, S. C.; Hirst, A. C.; Kleypas, J.; Matear, R.; Mikolajewicz, U.; Monfray, P.; Soldatov, V.; Spall, S. A.; Stouffer, R.

2004-09-01

We examine six different coupled climate model simulations to determine the ocean biological response to climate warming between the beginning of the industrial revolution and 2050. We use vertical velocity, maximum winter mixed layer depth, and sea ice cover to define six biomes. Climate warming leads to a contraction of the highly productive marginal sea ice biome by 42% in the Northern Hemisphere and 17% in the Southern Hemisphere, and leads to an expansion of the low productivity permanently stratified subtropical gyre biome by 4.0% in the Northern Hemisphere and 9.4% in the Southern Hemisphere. In between these, the subpolar gyre biome expands by 16% in the Northern Hemisphere and 7% in the Southern Hemisphere, and the seasonally stratified subtropical gyre contracts by 11% in both hemispheres. The low-latitude (mostly coastal) upwelling biome area changes only modestly. Vertical stratification increases, which would be expected to decrease nutrient supply everywhere, but increase the growing season length in high latitudes. We use satellite ocean color and climatological observations to develop an empirical model for predicting chlorophyll from the physical properties of the global warming simulations. Four features stand out in the response to global warming: (1) a drop in chlorophyll in the North Pacific due primarily to retreat of the marginal sea ice biome, (2) a tendency toward an increase in chlorophyll in the North Atlantic due to a complex combination of factors, (3) an increase in chlorophyll in the Southern Ocean due primarily to the retreat of and changes at the northern boundary of the marginal sea ice zone, and (4) a tendency toward a decrease in chlorophyll adjacent to the Antarctic continent due primarily to freshening within the marginal sea ice zone. We use three different primary production algorithms to estimate the response of primary production to climate warming based on our estimated chlorophyll concentrations. The three algorithms give

Allocation trade-off under climate warming in experimental amphibian populations

PubMed Central

Gao, Xu; Jin, Changnan; Camargo, Arley

2015-01-01

Climate change could either directly or indirectly cause population declines via altered temperature, rainfall regimes, food availability or phenological responses. However few studies have focused on allocation trade-offs between growth and reproduction under marginal resources, such as food scarce that may be caused by climate warming. Such critical changes may have an unpredicted impact on amphibian life-history parameters and even population dynamics. Here, we report an allocation strategy of adult anuran individuals involving a reproductive stage under experimental warming. Using outdoor mesocosm experiments we simulated a warming scenario likely to occur at the end of this century. We examined the effects of temperature (ambient vs. pre-/post-hibernation warming) and food availability (normal vs. low) on reproduction and growth parameters of pond frogs (Pelophylax nigromaculatus). We found that temperature was the major factor influencing reproductive time of female pond frogs, which showed a significant advancing under post-hibernation warming treatment. While feeding rate was the major factor influencing reproductive status of females, clutch size, and variation of body size for females, showed significant positive correlations between feeding rate and reproductive status, clutch size, or variation of body size. Our results suggested that reproduction and body size of amphibians might be modulated by climate warming or food availability variation. We believe this study provides some new evidence on allocation strategies suggesting that amphibians could adjust their reproductive output to cope with climate warming. PMID:26500832

Experimental evaluation of reproductive response to climate warming in an oviparous skink.

PubMed

Lu, Hongliang; Wang, Yong; Tang, Wenqi; DU, Weiguo

2013-06-01

The impact of climate warming on organisms is increasingly being recognized. The experimental evaluation of phenotypically plastic responses to warming is a critical step in understanding the biological effects and adaptive capacity of organisms to future climate warming. Oviparous Scincella modesta live in deeply-shaded habitats and they require low optimal temperatures during embryonic development, which makes them suitable subjects for testing the effects of warming on reproduction. We raised adult females and incubated their eggs under different thermal conditions that mimicked potential climate warming. Female reproduction, embryonic development and hatchling traits were monitored to evaluate the reproductive response to warming. Experimental warming induced females to lay eggs earlier, but it did not affect the developmental stage of embryos at oviposition or the reproductive output. The high temperatures experienced by gravid females during warming treatments reduced the incubation period and increased embryonic mortality. The locomotor performance of hatchlings was not affected by the maternal thermal environment, but it was affected by the warming treatment during embryonic development. Our results suggest that climate warming might have a profound effect on fitness-relevant traits both at embryonic and post-embryonic stages in oviparous lizards. © 2012 Wiley Publishing Asia Pty Ltd, ISZS and IOZ/CAS.

Processes Controlling Baseflow and Climatic Warming Effects in Merced River, Sierra Nevada, California

NASA Astrophysics Data System (ADS)

Liu, F.; Conklin, M. H.; Shaw, G.; Bales, R. C.; Conrad, M. E.; Rice, R.

2006-12-01

Sources of streamflow in Merced River were determined using stable isotopes and chemical tracers in order to improve our understanding of hydrologic controls on streamflow and their relationship with climatic warming in the region. Samples were collected from streamflow, groundwater, and natural springs from 2003 to 2006. Both stable isotopes and specific conductivity in streamflow showed a strong seasonality, with lower values from April to July during the snowmelt season, higher values from August to October during dry season, and intermediate values from November to March during winter rainfall and snowfall. Two components controlling baseflow (streamflow from August to October) in the Upper Merced River were identified: shallow subsurface runoff from snowmelt infiltration and groundwater from fractured bedrock. Conductivity in baseflow increased rapidly with discharge, following a power law (R2 > 0.96, p < 0.05), and peaked in October, indicating that the contribution of shallow subsurface runoff to baseflow was significant but decreased rapidly from August to October. Baseflow appears to be very sensitive to the snowmelt timing and regime. From 1976 to 2005, during a period of increasing temperature in the region, streamflow tended to decrease significantly during October (p < 0.05) and increase during March (p < 0.05). However, total annual precipitation did not change significantly, indicating that the shift in baseflow discharge is a result of the early onset of snowmelt due to climatic warming. If climatic warming continues in the region, baseflow in the Sierra Nevada may continue decreasing and water supply may suffer increased stress during the late summer, high water-demand period.

Impacts of climate extremes on gross primary production under global warming

DOE PAGES

Williams, I. N.; Torn, M. S.; Riley, W. J.; ...

2014-09-24

The impacts of historical droughts and heat-waves on ecosystems are often considered indicative of future global warming impacts, under the assumption that water stress sets in above a fixed high temperature threshold. Historical and future (RCP8.5) Earth system model (ESM) climate projections were analyzed in this study to illustrate changes in the temperatures for onset of water stress under global warming. The ESMs examined here predict sharp declines in gross primary production (GPP) at warm temperature extremes in historical climates, similar to the observed correlations between GPP and temperature during historical heat-waves and droughts. However, soil moisture increases at themore » warm end of the temperature range, and the temperature at which soil moisture declines with temperature shifts to a higher temperature. The temperature for onset of water stress thus increases under global warming and is associated with a shift in the temperature for maximum GPP to warmer temperatures. Despite the shift in this local temperature optimum, the impacts of warm extremes on GPP are approximately invariant when extremes are defined relative to the optimal temperature within each climate period. The GPP sensitivity to these relative temperature extremes therefore remains similar between future and present climates, suggesting that the heat- and drought-induced GPP reductions seen recently can be expected to be similar in the future, and may be underestimates of future impacts given model projections of increased frequency and persistence of heat-waves and droughts. The local temperature optimum can be understood as the temperature at which the combination of water stress and light limitations is minimized, and this concept gives insights into how GPP responds to climate extremes in both historical and future climate periods. Both cold (temperature and light-limited) and warm (water-limited) relative temperature extremes become more persistent in future climate

Impacts of climate extremes on gross primary production under global warming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, I. N.; Torn, M. S.; Riley, W. J.

The impacts of historical droughts and heat-waves on ecosystems are often considered indicative of future global warming impacts, under the assumption that water stress sets in above a fixed high temperature threshold. Historical and future (RCP8.5) Earth system model (ESM) climate projections were analyzed in this study to illustrate changes in the temperatures for onset of water stress under global warming. The ESMs examined here predict sharp declines in gross primary production (GPP) at warm temperature extremes in historical climates, similar to the observed correlations between GPP and temperature during historical heat-waves and droughts. However, soil moisture increases at themore » warm end of the temperature range, and the temperature at which soil moisture declines with temperature shifts to a higher temperature. The temperature for onset of water stress thus increases under global warming and is associated with a shift in the temperature for maximum GPP to warmer temperatures. Despite the shift in this local temperature optimum, the impacts of warm extremes on GPP are approximately invariant when extremes are defined relative to the optimal temperature within each climate period. The GPP sensitivity to these relative temperature extremes therefore remains similar between future and present climates, suggesting that the heat- and drought-induced GPP reductions seen recently can be expected to be similar in the future, and may be underestimates of future impacts given model projections of increased frequency and persistence of heat-waves and droughts. The local temperature optimum can be understood as the temperature at which the combination of water stress and light limitations is minimized, and this concept gives insights into how GPP responds to climate extremes in both historical and future climate periods. Both cold (temperature and light-limited) and warm (water-limited) relative temperature extremes become more persistent in future climate

Water Quality Outlet Works Prototype Tests, Warm Springs Dam Dry Creek, Russian River Basin Sonoma County, California

DTIC Science & Technology

1989-03-01

34.4* TECHNICAL REPORT HL-89-4 WATER QUALITY OUTLET WORKS PROTOTYPE TESTS, WARM SPRINGS DAM DRY CREEK, RUSSIAN RIVER BASIN AD-A207 058 SONOMA COUNTY , CALIFORNIA...Clawflcation) [7 Water Quality Outlet Works Prototype Tests, Warm Springs Dam, Dry Creek, Russian River Basin, Sonoma County , California 12. PERSONAL...Cointogobvil Be,,pesso Figur 1. iciniyama Pealm WATER QUALITY OUTLET WORKS PROTOTYPE TESTS WARM SPRINGS DAM, DRY CREEK, RUSSIAN RIVER BASIN SONOMA COUNTY , CALIFORNIA

Future Warming Patterns Linked to Today's Climate Variability.

PubMed

Dai, Aiguo

2016-01-11

The reliability of model projections of greenhouse gas (GHG)-induced future climate change is often assessed based on models' ability to simulate the current climate, but there has been little evidence that connects the two. In fact, this practice has been questioned because the GHG-induced future climate change may involve additional physical processes that are not important for the current climate. Here I show that the spatial patterns of the GHG-induced future warming in the 21(st) century is highly correlated with the patterns of the year-to-year variations of surface air temperature for today's climate, with areas of larger variations during 1950-1979 having more GHG-induced warming in the 21(st) century in all climate models. Such a relationship also exists in other climate fields such as atmospheric water vapor, and it is evident in observed temperatures from 1950-2010. The results suggest that many physical processes may work similarly in producing the year-to-year climate variations in the current climate and the GHG-induced long-term changes in the 21(st) century in models and in the real world. They support the notion that models that simulate present-day climate variability better are likely to make more reliable predictions of future climate change.

Metagenomics-Enabled Understanding of Soil Microbial Feedbacks to Climate Warming

NASA Astrophysics Data System (ADS)

Zhou, J.; Wu, L.; Zhili, H.; Kostas, K.; Luo, Y.; Schuur, E. A. G.; Cole, J. R.; Tiedje, J. M.

2014-12-01

Understanding the response of biological communities to climate warming is a central issue in ecology and global change biology, but it is poorly understood microbial communities. To advance system-level predictive understanding of the feedbacks of belowground microbial communities to multiple climate change factors and their impacts on soil carbon (C) and nitrogen (N) cycling processes, we have used integrated metagenomic technologies (e.g., target gene and shotgun metagenome sequencing, GeoChip, and isotope) to analyze soil microbial communities from experimental warming sites in Alaska (AK) and Oklahoma (OK), and long-term laboratory incubation. Rapid feedbacks of microbial communities to warming were observed in the AK site. Consistent with the changes in soil temperature, moisture and ecosystem respiration, microbial functional community structure was shifted after only 1.5-year warming, indicating rapid responses and high sensitivity of this permafrost ecosystem to climate warming. Also, warming stimulated not only functional genes involved in aerobic respiration of both labile and recalcitrant C, contributing to an observed 24% increase in 2010 growing season and 56% increase of decomposition of a standard substrate, but also functional genes for anaerobic processes (e.g., denitrification, sulfate reduction, methanogenesis). Further comparisons by shotgun sequencing showed significant differences of microbial community structure between AK and OK sites. The OK site was enriched in genes annotated for cellulose degradation, CO2 production, denitrification, sporulation, heat shock response, and cellular surface structures (e.g., trans-membrane transporters for glucosides), while the AK warmed plots were enriched in metabolic pathways related to labile C decomposition. Together, our results demonstrate the vulnerability of permafrost ecosystem C to climate warming and the importance of microbial feedbacks in mediating such vulnerability.

Climatic irregular staircases: generalized acceleration of global warming.

PubMed

De Saedeleer, Bernard

2016-01-27

Global warming rates mentioned in the literature are often restricted to a couple of arbitrary periods of time, or of isolated values of the starting year, lacking a global view. In this study, we perform on the contrary an exhaustive parametric analysis of the NASA GISS LOTI data, and also of the HadCRUT4 data. The starting year systematically varies between 1880 and 2002, and the averaging period from 5 to 30 yr - not only decades; the ending year also varies . In this way, we uncover a whole unexplored space of values for the global warming rate, and access the full picture. Additionally, stairstep averaging and linear least squares fitting to determine climatic trends have been sofar exclusive. We propose here an original hybrid method which combines both approaches in order to derive a new type of climatic trend. We find that there is an overall acceleration of the global warming whatever the value of the averaging period, and that 99.9% of the 3029 Earth's climatic irregular staircases are rising. Graphical evidence is also given that choosing an El Niño year as starting year gives lower global warming rates - except if there is a volcanic cooling in parallel. Our rates agree and generalize several results mentioned in the literature.

Impacts of climate warming on terrestrial ectotherms across latitude.

PubMed

Deutsch, Curtis A; Tewksbury, Joshua J; Huey, Raymond B; Sheldon, Kimberly S; Ghalambor, Cameron K; Haak, David C; Martin, Paul R

2008-05-06

The impact of anthropogenic climate change on terrestrial organisms is often predicted to increase with latitude, in parallel with the rate of warming. Yet the biological impact of rising temperatures also depends on the physiological sensitivity of organisms to temperature change. We integrate empirical fitness curves describing the thermal tolerance of terrestrial insects from around the world with the projected geographic distribution of climate change for the next century to estimate the direct impact of warming on insect fitness across latitude. The results show that warming in the tropics, although relatively small in magnitude, is likely to have the most deleterious consequences because tropical insects are relatively sensitive to temperature change and are currently living very close to their optimal temperature. In contrast, species at higher latitudes have broader thermal tolerance and are living in climates that are currently cooler than their physiological optima, so that warming may even enhance their fitness. Available thermal tolerance data for several vertebrate taxa exhibit similar patterns, suggesting that these results are general for terrestrial ectotherms. Our analyses imply that, in the absence of ameliorating factors such as migration and adaptation, the greatest extinction risks from global warming may be in the tropics, where biological diversity is also greatest.

Impacts of climate warming on terrestrial ectotherms across latitude

PubMed Central

Deutsch, Curtis A.; Tewksbury, Joshua J.; Huey, Raymond B.; Sheldon, Kimberly S.; Ghalambor, Cameron K.; Haak, David C.; Martin, Paul R.

2008-01-01

The impact of anthropogenic climate change on terrestrial organisms is often predicted to increase with latitude, in parallel with the rate of warming. Yet the biological impact of rising temperatures also depends on the physiological sensitivity of organisms to temperature change. We integrate empirical fitness curves describing the thermal tolerance of terrestrial insects from around the world with the projected geographic distribution of climate change for the next century to estimate the direct impact of warming on insect fitness across latitude. The results show that warming in the tropics, although relatively small in magnitude, is likely to have the most deleterious consequences because tropical insects are relatively sensitive to temperature change and are currently living very close to their optimal temperature. In contrast, species at higher latitudes have broader thermal tolerance and are living in climates that are currently cooler than their physiological optima, so that warming may even enhance their fitness. Available thermal tolerance data for several vertebrate taxa exhibit similar patterns, suggesting that these results are general for terrestrial ectotherms. Our analyses imply that, in the absence of ameliorating factors such as migration and adaptation, the greatest extinction risks from global warming may be in the tropics, where biological diversity is also greatest. PMID:18458348

A warming tropical central Pacific dries the lower stratosphere

NASA Astrophysics Data System (ADS)

Ding, Qinghua; Fu, Qiang

2018-04-01

The amount of water vapor in the tropical lower stratosphere (TLS), which has an important influence on the radiative energy budget of the climate system, is modulated by the temperature variability of the tropical tropopause layer (TTL). The TTL temperature variability is caused by a complex combination of the stratospheric quasi-biennial oscillation (QBO), tropospheric convective processes in the tropics, and the Brewer-Dobson circulation (BDC) driven by mid-latitude and subtropical atmospheric waves. In 2000, the TLS water vapor amount exhibited a stepwise transition to a dry phase, apparently caused by a change in the BDC. In this study, we present observational and modeling evidence that the epochal change of water vapor between the periods of 1992-2000 and 2001-2005 was also partly caused by a concurrent sea surface temperature (SST) warming in the tropical central Pacific. This SST warming cools the TTL above by enhancing the equatorial wave-induced upward motion near the tropopause, which consequently reduces the amount of water vapor entering the stratosphere. The QBO affects the TLS water vapor primarily on inter-annual timescales, whereas a classical El Niño southern oscillation (ENSO) event has small effect on tropical mean TLS water vapor because its responses are longitudinally out of phase. This study suggests that the tropical central Pacific SST is another driver of TLS water vapor variability on inter-decadal timescales and the tropical SST changes could contribute to about 30% of the step-wise drop of the lower stratospheric water vapor from 1992-2000 to 2001-2005.

Warm Dry Weather Conditions Cause of 2016 Fort McMurray Wild Forest Fire and Associated Air Quality

NASA Astrophysics Data System (ADS)

de Azevedo, S. C.; Singh, R. P.; da Silva, E. A., Sr.

2016-12-01

The climate change is evident from the increasing temperature around the world, day to day life and increasing frequency of natural hazards. The warm and dry conditions are the cause of frequent forest fires around the globe. Forest fires severely affect the air quality and human health. Multi sensor satellites and dense network of ground stations provide information about vegetation health, meteorological, air quality and atmospheric parameters. We have carried out detailed analysis of satellite and ground data of wild forest fire that occurred in May 2016 in Fort McMurray, Alberta, Canada. This wild forest fire destroyed 10 per cent of Fort McMurray's housing and forced more than 90,000 people to evacuate the surrounding areas. Our results show that the warm and dry conditions with low rainfall were the cause of Fort McMurray wild fire. The air quality parameters (particulate matter, CO, ozone, NO2, methane) and greenhouse gases measured from Atmospheric Infrared Sounder (AIRS) satellite show enhanced levels soon after the forest fire. The emissions from the forest fire affected health of population living in surrounding areas up to 300 km radius.

Climatic irregular staircases: generalized acceleration of global warming

PubMed Central

De Saedeleer, Bernard

2016-01-01

Global warming rates mentioned in the literature are often restricted to a couple of arbitrary periods of time, or of isolated values of the starting year, lacking a global view. In this study, we perform on the contrary an exhaustive parametric analysis of the NASA GISS LOTI data, and also of the HadCRUT4 data. The starting year systematically varies between 1880 and 2002, and the averaging period from 5 to 30 yr — not only decades; the ending year also varies . In this way, we uncover a whole unexplored space of values for the global warming rate, and access the full picture. Additionally, stairstep averaging and linear least squares fitting to determine climatic trends have been sofar exclusive. We propose here an original hybrid method which combines both approaches in order to derive a new type of climatic trend. We find that there is an overall acceleration of the global warming whatever the value of the averaging period, and that 99.9% of the 3029 Earth’s climatic irregular staircases are rising. Graphical evidence is also given that choosing an El Niño year as starting year gives lower global warming rates — except if there is a volcanic cooling in parallel. Our rates agree and generalize several results mentioned in the literature. PMID:26813867

Wine tasting based on emotional responses: An expedite approach to distinguish between warm and cool climate dry red wine styles.

PubMed

Coste, Amaury; Sousa, Paulo; Malfeito-Ferreira, Manuel

2018-04-01

In this study, we improved an empirical tasting sheet including emotional responses and common sensory attributes. An Optimized Descriptive Profile (ODP) was run to characterize different red wines according to sensory descriptors used in the improved sheet. A total of 5 wines were evaluated by a Consumer Panel (CP) of 103 subjects (36 females, 67 males) using the improved sheet and a Check-All-That-Apply (CATA) list of 25 emotions. In the ODP, the panel identified the main discriminating sensory attributes as "Complexity", "Astringency" and "Duration of the wine fragrance". However, this analysis did not allow for differentiating very distinct dry red wine styles originating from warmer or cooler regions. On the contrary, Principal Component Analysis of emotional attributes demonstrated that these two wine styles could be easily distinguished. In particular, wine with a red-brick color, complex smell and aggressive mouthfeel consistent with those from cooler regions was less liked by the CP than a warm climate gold-awarded wine. Although receiving lower scores considering its color and smell, the former wine was regarded as the most "surprising" in the CATA. Copyright © 2017 Elsevier Ltd. All rights reserved.

Is "Warm Arctic, Cold Continent" A Fingerprint Pattern of Climate Change?

NASA Astrophysics Data System (ADS)

Hoerling, M. P.; Sun, L.; Perlwitz, J.

2015-12-01

Cold winters and cold waves have recently occurred in Europe, central Asia and the Midwest to eastern United States, even as global mean temperatures set record highs and Arctic amplification of surface warming continued. Since 1979, Central Asia winter temperatures have in fact declined. Conjecture has it that more cold extremes over the mid-latitude continents should occur due to global warming and the impacts of Arctic sea ice loss. A Northern Hemisphere temperature signal termed the "Warm Arctic, Cold Continent" pattern has thus been surmised. Here we use a multi-model approach to test the hypothesis that such a pattern is indeed symptomatic of climate change. Diagnosis of a large model ensemble of historical climate simulations shows some individual realizations to yield cooling trends over Central Asia, but importantly the vast majority show warming. The observed cooling has thus likely been a low probability state of internal variability, not a fingerprint of forced climate change. We show that daily temperature variations over continents decline in winter due to global warming, and cold waves become less likely. This is partly related to diminution of Arctic cold air reservoirs due to warming-induced sea ice loss. Nonetheless, we find some evidence and present a physical basis that Arctic sea ice loss alone can induce a winter cooling over Central Asia, though with a magnitude that is appreciably smaller than the overall radiative-forced warming signal. Our results support the argument that recent cooling trends over central Asia, and cold extreme events over the winter continents, have principally resulted from atmospheric internal variability and have been neither a forced response to Arctic seas ice loss nor a symptom of global warming. The paradigm of climate change is thus better expressed as "Warm Arctic, Warm Continent" for the NH winter.

Using physiology to predict the responses of ants to climatic warming.

PubMed

Diamond, Sarah E; Penick, Clint A; Pelini, Shannon L; Ellison, Aaron M; Gotelli, Nicholas J; Sanders, Nathan J; Dunn, Robert R

2013-12-01

Physiological intolerance of high temperatures places limits on organismal responses to the temperature increases associated with global climatic change. Because ants are geographically widespread, ecologically diverse, and thermophilic, they are an ideal system for exploring the extent to which physiological tolerance can predict responses to environmental change. Here, we expand on simple models that use thermal tolerance to predict the responses of ants to climatic warming. We investigated the degree to which changes in the abundance of ants under warming reflect reductions in the thermal niche space for their foraging. In an eastern deciduous forest system in the United States with approximately 40 ant species, we found that for some species, the loss of thermal niche space for foraging was related to decreases in abundance with increasing experimental climatic warming. However, many ant species exhibited no loss of thermal niche space. For one well-studied species, Temnothorax curvispinosus, we examined both survival of workers and growth of colonies (a correlate of reproductive output) as functions of temperature in the laboratory, and found that the range of thermal tolerances for colony growth was much narrower than for survival of workers. We evaluated these functions in the context of experimental climatic warming and found that the difference in the responses of these two attributes to temperature generates differences in the means and especially the variances of expected fitness under warming. The expected mean growth of colonies was optimized at intermediate levels of warming (2-4°C above ambient); yet, the expected variance monotonically increased with warming. In contrast, the expected mean and variance of the survival of workers decreased when warming exceeded 4°C above ambient. Together, these results for T. curvispinosus emphasize the importance of measuring reproduction (colony growth) in the context of climatic change: indeed, our examination

Sustained climate warming drives declining marine biological productivity

NASA Astrophysics Data System (ADS)

Moore, J. Keith; Fu, Weiwei; Primeau, Francois; Britten, Gregory L.; Lindsay, Keith; Long, Matthew; Doney, Scott C.; Mahowald, Natalie; Hoffman, Forrest; Randerson, James T.

2018-03-01

Climate change projections to the year 2100 may miss physical-biogeochemical feedbacks that emerge later from the cumulative effects of climate warming. In a coupled climate simulation to the year 2300, the westerly winds strengthen and shift poleward, surface waters warm, and sea ice disappears, leading to intense nutrient trapping in the Southern Ocean. The trapping drives a global-scale nutrient redistribution, with net transfer to the deep ocean. Ensuing surface nutrient reductions north of 30°S drive steady declines in primary production and carbon export (decreases of 24 and 41%, respectively, by 2300). Potential fishery yields, constrained by lower–trophic-level productivity, decrease by more than 20% globally and by nearly 60% in the North Atlantic. Continued high levels of greenhouse gas emissions could suppress marine biological productivity for a millennium.

The climate response of the Indo-Pacific warm pool to glacial sea level

NASA Astrophysics Data System (ADS)

Di Nezio, Pedro N.; Timmermann, Axel; Tierney, Jessica E.; Jin, Fei-Fei; Otto-Bliesner, Bette; Rosenbloom, Nan; Mapes, Brian; Neale, Rich; Ivanovic, Ruza F.; Montenegro, Alvaro

2016-06-01

Growing climate proxy evidence suggests that changes in sea level are important drivers of tropical climate change on glacial-interglacial timescales. These paleodata suggest that rainfall patterns over the Indo-Pacific warm pool (IPWP) are highly sensitive to the landmass configuration of the Maritime Continent and that lowered sea level contributed to large-scale drying during the Last Glacial Maximum (LGM, approximately 21,000 years B.P.). Using the Community Earth System Model Version 1.2 (CESM1), we investigate the mechanisms by which lowered sea level influenced the climate of the IPWP during the LGM. The CESM1 simulations show that, in agreement with previous hypotheses, changes in atmospheric circulation are initiated by the exposure of the Sunda and Sahul shelves. Ocean dynamical processes amplify the changes in atmospheric circulation by increasing the east-west sea surface temperature (SST) gradient along the equatorial Indian Ocean. The coupled mechanism driving this response is akin to the Bjerknes feedback and results in a large-scale climatic reorganization over the Indian Ocean with impacts extending from east Africa to the western tropical Pacific. Unlike exposure of the Sunda shelf, exposure of Sahul shelf and the associated changes in surface albedo play a key role because of the positive feedback. This mechanism could explain the pattern of dry (wet) eastern (western) Indian Ocean identified in climate proxies and LGM simulations. However, this response also requires a strengthened SST gradient along the equatorial Indian Ocean, a pattern that is not evident in marine paleoreconstructions. Strategies to resolve this issue are discussed.

Possible climate warming effects on vegetation, forests, biotic (insect, pathogene) disturbances and agriculture in Central Siberia for 1960- 2050

NASA Astrophysics Data System (ADS)

Tchebakova, N. M.; Parfenova, E. I.; Soja, A. J.; Lysanova, G. I.; Baranchikov, Y. N.; Kuzmina, N. A.

2012-04-01

Regional Siberian studies have already registered climate warming over the last half a century (1960-2010). Our analysis showed that winters are already 2-3°C warmer in the north and 1-2°C warmer in the south by 2010. Summer temperatures increased by 1°C in the north and by 1-2°C in the south. Change in precipitation is more complicated, increasing on average 10% in middle latitudes and decreasing 10-20% in the south, promoting local drying in already dry landscapes. Our goal was to summarize results of research we have done for the last decade in the context of climate warming and its consequences for biosystems in Central Siberia. We modeled climate change effects on vegetation shifts, on forest composition and agriculture change, on the insect Siberian moth (Dendrolimus suprans sibiricus Tschetv) and pathogene (Lophodermium pinastri Chev) ranges in Central Siberia for a century (1960-2050) based on historical climate data and GCM-predicted data. Principal results are: In the warmer and drier climate projected by these scenarios, Siberian forests are predicted to decrease and shift northwards and forest-steppe and steppe ecosystems are predicted to dominate over 50% of central Siberia due to the dryer climate by 2080. Permafrost is not predicted to thaw deep enough to sustain dark (Pinus sibirica, Abies sibirica, and Picea obovata) taiga. Over eastern Siberia, larch (Larix dahurica) taiga is predicted to continue to be the dominant zonobiome because of its ability to withstand continuous permafrost. The model also predicts new temperate broadleaf forest and forest-steppe habitats; At least half of central Siberia is predicted to be climatically suitable for agriculture at the end of the century although potential croplands would be limited by the availability of suitable soils agriculture in central Siberia would likely benefit from climate warming Crop production may twofold increase as climate warms during the century; traditional crops (grain, potato

Both life-history plasticity and local adaptation will shape range-wide responses to climate warming in the tundra plant Silene acaulis.

PubMed

Peterson, Megan L; Doak, Daniel F; Morris, William F

2018-04-01

Many predictions of how climate change will impact biodiversity have focused on range shifts using species-wide climate tolerances, an approach that ignores the demographic mechanisms that enable species to attain broad geographic distributions. But these mechanisms matter, as responses to climate change could fundamentally differ depending on the contributions of life-history plasticity vs. local adaptation to species-wide climate tolerances. In particular, if local adaptation to climate is strong, populations across a species' range-not only those at the trailing range edge-could decline sharply with global climate change. Indeed, faster rates of climate change in many high latitude regions could combine with local adaptation to generate sharper declines well away from trailing edges. Combining 15 years of demographic data from field populations across North America with growth chamber warming experiments, we show that growth and survival in a widespread tundra plant show compensatory responses to warming throughout the species' latitudinal range, buffering overall performance across a range of temperatures. However, populations also differ in their temperature responses, consistent with adaptation to local climate, especially growing season temperature. In particular, warming begins to negatively impact plant growth at cooler temperatures for plants from colder, northern populations than for those from warmer, southern populations, both in the field and in growth chambers. Furthermore, the individuals and maternal families with the fastest growth also have the lowest water use efficiency at all temperatures, suggesting that a trade-off between growth and water use efficiency could further constrain responses to forecasted warming and drying. Taken together, these results suggest that populations throughout species' ranges could be at risk of decline with continued climate change, and that the focus on trailing edge populations risks overlooking the largest

Evidence for 20th century climate warming and wetland drying in the North American Prairie Pothole Region

USGS Publications Warehouse

Werner, B.A.; Johnson, W. Carter; Guntenspergen, Glenn R.

2013-01-01

The Prairie Pothole Region (PPR) of North America is a globally important resource that provides abundant and valuable ecosystem goods and services in the form of biodiversity, groundwater recharge, water purification, flood attenuation, and water and forage for agriculture. Numerous studies have found these wetlands, which number in the millions, to be highly sensitive to climate variability. Here, we compare wetland conditions between two 30-year periods (1946–1975; 1976–2005) using a hindcast simulation approach to determine if recent climate warming in the region has already resulted in changes in wetland condition. Simulations using the WETLANDSCAPE model show that 20th century climate change may have been sufficient to have a significant impact on wetland cover cycling. Modeled wetlands in the PPR's western Canadian prairies show the most dramatic effects: a recent trend toward shorter hydroperiods and less dynamic vegetation cycles, which already may have reduced the productivity of hundreds of wetland-dependent species.

Evidence for 20th century climate warming and wetland drying in the North American Prairie Pothole Region.

PubMed

Werner, Brett A; Johnson, W Carter; Guntenspergen, Glenn R

2013-09-01

The Prairie Pothole Region (PPR) of North America is a globally important resource that provides abundant and valuable ecosystem goods and services in the form of biodiversity, groundwater recharge, water purification, flood attenuation, and water and forage for agriculture. Numerous studies have found these wetlands, which number in the millions, to be highly sensitive to climate variability. Here, we compare wetland conditions between two 30-year periods (1946-1975; 1976-2005) using a hindcast simulation approach to determine if recent climate warming in the region has already resulted in changes in wetland condition. Simulations using the WETLANDSCAPE model show that 20th century climate change may have been sufficient to have a significant impact on wetland cover cycling. Modeled wetlands in the PPR's western Canadian prairies show the most dramatic effects: a recent trend toward shorter hydroperiods and less dynamic vegetation cycles, which already may have reduced the productivity of hundreds of wetland-dependent species.

Sphagnum-dwelling testate amoebae in subarctic bogs are more sensitive to soil warming in the growing season than in winter: the results of eight-year field climate manipulations.

PubMed

Tsyganov, Andrey N; Aerts, Rien; Nijs, Ivan; Cornelissen, Johannes H C; Beyens, Louis

2012-05-01

Sphagnum-dwelling testate amoebae are widely used in paleoclimate reconstructions as a proxy for climate-induced changes in bogs. However, the sensitivity of proxies to seasonal climate components is an important issue when interpreting proxy records. Here, we studied the effects of summer warming, winter snow addition solely and winter snow addition together with spring warming on testate amoeba assemblages after eight years of experimental field climate manipulations. All manipulations were accomplished using open top chambers in a dry blanket bog located in the sub-Arctic (Abisko, Sweden). We estimated sensitivity of abundance, diversity and assemblage structure of living and empty shell assemblages of testate amoebae in the living and decaying layers of Sphagnum. Our results show that, in a sub-arctic climate, testate amoebae are more sensitive to climate changes in the growing season than in winter. Summer warming reduced species richness and shifted assemblage composition towards predominance of xerophilous species for the living and empty shell assemblages in both layers. The higher soil temperatures during the growing season also decreased abundance of empty shells in both layers hinting at a possible increase in their decomposition rates. Thus, although possible effects of climate changes on preservation of empty shells should always be taken into account, species diversity and structure of testate amoeba assemblages in dry subarctic bogs are sensitive proxies for climatic changes during the growing season. Copyright © 2011 Elsevier GmbH. All rights reserved.

How Does Snow Persistence Relate to Annual Streamflow in Mountain Watersheds of the Western U.S. With Wet Maritime and Dry Continental Climates?

NASA Astrophysics Data System (ADS)

Hammond, John C.; Saavedra, Freddy A.; Kampf, Stephanie K.

2018-04-01

With climate warming, many regions are experiencing changes in snow accumulation and persistence. These changes are known to affect streamflow volume, but the magnitude of the effect varies between regions. This research evaluates whether variables derived from remotely sensed snow cover can be used to estimate annual streamflow at the small watershed scale across the western U.S., a region with a wide range of climate types. We compared snow cover variables derived from MODIS, snow persistence (SP), and snow season (SS), to more commonly utilized metrics, snow fraction (fraction of precipitation falling as snow, SF), and peak snow water equivalent (SWE). Each variable represents different information about snow, and this comparison assesses similarities and differences between the snow metrics. Next, we evaluated how two snow variables, SP and SWE, related to annual streamflow (Q) for 119 USGS reference watersheds and examined whether these relationships varied for wet/warm (precipitation surplus) and dry/cold (precipitation deficit) watersheds. Results showed high correlations between all snow variables, but the slopes of these relationships differed between climates, with wet/warm watersheds displaying lower SF and higher SWE for the same SP. In dry/cold watersheds, both SP and SNODAS SWE correlated with Q spatially across all watersheds and over time within individual watersheds. We conclude that SP can be used to map spatial patterns of annual streamflow generation in dry/cold parts of the region. Applying this approach to the Upper Colorado River Basin demonstrates that 50% of streamflow comes from areas >3,000 masl. If the relationship between SP and Q is similar in other dry/cold regions, this approach could be used to estimate annual streamflow in ungauged basins.

Irrigation enhances local warming with greater nocturnal warming effects than daytime cooling effects

NASA Astrophysics Data System (ADS)

Chen, Xing; Jeong, Su-Jong

2018-02-01

To meet the growing demand for food, land is being managed to be more productive using agricultural intensification practices, such as the use of irrigation. Understanding the specific environmental impacts of irrigation is a critical part of using it as a sustainable way to provide food security. However, our knowledge of irrigation effects on climate is still limited to daytime effects. This is a critical issue to define the effects of irrigation on warming related to greenhouse gases (GHGs). This study shows that irrigation led to an increasing temperature (0.002 °C year-1) by enhancing nighttime warming (0.009 °C year-1) more than daytime cooling (-0.007 °C year-1) during the dry season from 1961-2004 over the North China Plain (NCP), which is one of largest irrigated areas in the world. By implementing irrigation processes in regional climate model simulations, the consistent warming effect of irrigation on nighttime temperatures over the NCP was shown to match observations. The intensive nocturnal warming is attributed to energy storage in the wetter soil during the daytime, which contributed to the nighttime surface warming. Our results suggest that irrigation could locally amplify the warming related to GHGs, and this effect should be taken into account in future climate change projections.

Multi-season climate synchronized historical fires in dry forests (1650-1900), northern Rockies, U.S.A.

PubMed

Heyerdahl, Emily K; Morgan, Penelope; Riser, James P

2008-03-01

Our objective was to infer the climate drivers of regionally synchronous fire years in dry forests of the U.S. northern Rockies in Idaho and western Montana. During our analysis period (1650-1900), we reconstructed fires from 9245 fire scars on 576 trees (mostly ponderosa pine, Pinus ponderosa P. & C. Lawson) at 21 sites and compared them to existing tree-ring reconstructions of climate (temperature and the Palmer Drought Severity Index [PDSI]) and large-scale climate patterns that affect modern spring climate in this region (El Niño Southern Oscillation [ENSO] and the Pacific Decadal Oscillation [PDO]). We identified 32 regional-fire years as those with five or more sites with fire. Fires were remarkably widespread during such years, including one year (1748) in which fires were recorded at 10 sites across what are today seven national forests plus one site on state land. During regional-fire years, spring-summers were significantly warm and summers were significantly warm-dry whereas the opposite conditions prevailed during the 99 years when no fires were recorded at any of our sites (no-fire years). Climate in prior years was not significantly associated with regional- or no-fire years. Years when fire was recorded at only a few of our sites occurred under a broad range of climate conditions, highlighting the fact that the regional climate drivers of fire are most evident when fires are synchronized across a large area. No-fire years tended to occur during La Niña years, which tend to have anomalously deep snowpacks in this region. However, ENSO was not a significant driver of regional-fire years, consistent with the greater influence of La Niña than El Niño conditions on the spring climate of this region. PDO was not a significant driver of past fire, despite being a strong driver of modern spring climate and modern regional-fire years in the northern Rockies.

Sustained climate warming drives declining marine biological productivity

DOE PAGES

Moore, J. Keith; Fu, Weiwei; Primeau, Francois; ...

2018-03-01

Climate change projections to the year 2100 may miss physical-biogeochemical feedbacks that emerge later from the cumulative effects of climate warming. In a coupled climate simulation to the year 2300, the westerly winds strengthen and shift poleward, surface waters warm, and sea ice disappears, leading to intense nutrient trapping in the Southern Ocean. The trapping drives a global-scale nutrient redistribution, with net transfer to the deep ocean. Ensuing surface nutrient reductions north of 30°S drive steady declines in primary production and carbon export (decreases of 24 and 41%, respectively, by 2300). Potential fishery yields, constrained by lower–trophic-level productivity, decrease bymore » more than 20% globally and by nearly 60% in the North Atlantic. Continued high levels of greenhouse gas emissions could suppress marine biological productivity for a millennium.« less

Sustained climate warming drives declining marine biological productivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, J. Keith; Fu, Weiwei; Primeau, Francois

Climate change projections to the year 2100 may miss physical-biogeochemical feedbacks that emerge later from the cumulative effects of climate warming. In a coupled climate simulation to the year 2300, the westerly winds strengthen and shift poleward, surface waters warm, and sea ice disappears, leading to intense nutrient trapping in the Southern Ocean. The trapping drives a global-scale nutrient redistribution, with net transfer to the deep ocean. Ensuing surface nutrient reductions north of 30°S drive steady declines in primary production and carbon export (decreases of 24 and 41%, respectively, by 2300). Potential fishery yields, constrained by lower–trophic-level productivity, decrease bymore » more than 20% globally and by nearly 60% in the North Atlantic. Continued high levels of greenhouse gas emissions could suppress marine biological productivity for a millennium.« less

Global mean temperature indicators linked to warming levels avoiding climate risks

NASA Astrophysics Data System (ADS)

Pfleiderer, Peter; Schleussner, Carl-Friedrich; Mengel, Matthias; Rogelj, Joeri

2018-06-01

International climate policy uses global mean temperature rise limits as proxies for societally acceptable levels of climate change. These limits are informed by risk assessments which draw upon projections of climate impacts under various levels of warming. Here we illustrate that indicators used to define limits of warming and those used to track the evolution of the Earth System under climate change are not directly comparable. Depending on the methodological approach, differences can be time-variant and up to 0.2 °C for a warming of 1.5 °C above pre-industrial levels. This might lead to carbon budget overestimates of about 10 years of continued year-2015 emissions, and about a 10% increase in estimated 2100 sea-level rise. Awareness of this definitional mismatch is needed for a more effective communication between scientists and decision makers, as well as between the impact and physical climate science communities.

Enhanced Climatic Warming Over the Tibetan Plateau Due to Doubling CO2: A Model Study

NASA Technical Reports Server (NTRS)

Chen, Baode; Chao, Winston C.; Liu, Xiaodong; Lau, William K. M. (Technical Monitor)

2001-01-01

A number of studies have presented the evidences that surface climate change associated with global warming at high elevation sites shows more pronounced warming than at low elevations, i.e. an elevation dependency of climatic warming pointed out that snow-albedo feedback may be responsible for the excessive warming in the Swiss Alps. From an ensemble of climate change experiments of increasing greenhouse gases and aerosols using an air-sea coupled climate model, Eyre and Raw (1999) found a marked elevation dependency of the simulated surface screen temperature increase over the Rocky Mountains. Using almost all available instrumental records, Liu and Chen (2000) showed that the main portion of the Tibetan Plateau (TP) has experienced significant ground temperature warming since the middlebrows, especially in winter, and that there is a tendency for the warming trend to increase with elevation in the TP as well as its surrounding areas. In this paper, we will investigate the mechanism of elevation dependency of climatic warming in the TP by using a high-resolution regional climate model.

Hydrologic Response and Watershed Sensitivity to Climate Warming in California's Sierra Nevada

PubMed Central

Null, Sarah E.; Viers, Joshua H.; Mount, Jeffrey F.

2010-01-01

This study focuses on the differential hydrologic response of individual watersheds to climate warming within the Sierra Nevada mountain region of California. We describe climate warming models for 15 west-slope Sierra Nevada watersheds in California under unimpaired conditions using WEAP21, a weekly one-dimensional rainfall-runoff model. Incremental climate warming alternatives increase air temperature uniformly by 2°, 4°, and 6°C, but leave other climatic variables unchanged from observed values. Results are analyzed for changes in mean annual flow, peak runoff timing, and duration of low flow conditions to highlight which watersheds are most resilient to climate warming within a region, and how individual watersheds may be affected by changes to runoff quantity and timing. Results are compared with current water resources development and ecosystem services in each watershed to gain insight into how regional climate warming may affect water supply, hydropower generation, and montane ecosystems. Overall, watersheds in the northern Sierra Nevada are most vulnerable to decreased mean annual flow, southern-central watersheds are most susceptible to runoff timing changes, and the central portion of the range is most affected by longer periods with low flow conditions. Modeling results suggest the American and Mokelumne Rivers are most vulnerable to all three metrics, and the Kern River is the most resilient, in part from the high elevations of the watershed. Our research seeks to bridge information gaps between climate change modeling and regional management planning, helping to incorporate climate change into the development of regional adaptation strategies for Sierra Nevada watersheds. PMID:20368984

Assessing forest vulnerability to climate warming using a process-based model of tree growth: bad prospects for rear-edges.

PubMed

Sánchez-Salguero, Raúl; Camarero, Jesus Julio; Gutiérrez, Emilia; González Rouco, Fidel; Gazol, Antonio; Sangüesa-Barreda, Gabriel; Andreu-Hayles, Laia; Linares, Juan Carlos; Seftigen, Kristina

2017-07-01

Growth models can be used to assess forest vulnerability to climate warming. If global warming amplifies water deficit in drought-prone areas, tree populations located at the driest and southernmost distribution limits (rear-edges) should be particularly threatened. Here, we address these statements by analyzing and projecting growth responses to climate of three major tree species (silver fir, Abies alba; Scots pine, Pinus sylvestris; and mountain pine, Pinus uncinata) in mountainous areas of NE Spain. This region is subjected to Mediterranean continental conditions, it encompasses wide climatic, topographic and environmental gradients, and, more importantly, it includes rear-edges of the continuous distributions of these tree species. We used tree-ring width data from a network of 110 forests in combination with the process-based Vaganov-Shashkin-Lite growth model and climate-growth analyses to forecast changes in tree growth during the 21st century. Climatic projections were based on four ensembles CO 2 emission scenarios. Warm and dry conditions during the growing season constrain silver fir and Scots pine growth, particularly at the species rear-edge. By contrast, growth of high-elevation mountain pine forests is enhanced by climate warming. The emission scenario (RCP 8.5) corresponding to the most pronounced warming (+1.4 to 4.8 °C) forecasted mean growth reductions of -10.7% and -16.4% in silver fir and Scots pine, respectively, after 2050. This indicates that rising temperatures could amplify drought stress and thus constrain the growth of silver fir and Scots pine rear-edge populations growing at xeric sites. Contrastingly, mountain pine growth is expected to increase by +12.5% due to a longer and warmer growing season. The projections of growth reduction in silver fir and Scots pine portend dieback and a contraction of their species distribution areas through potential local extinctions of the most vulnerable driest rear-edge stands. Our modeling

Climate warming enhances snow avalanche risk in the Western Himalayas

PubMed Central

Ballesteros-Cánovas, J. A.; Trappmann, D.; Madrigal-González, J.; Eckert, N.; Stoffel, M.

2018-01-01

Ongoing climate warming has been demonstrated to impact the cryosphere in the Indian Himalayas, with substantial consequences for the risk of disasters, human well-being, and terrestrial ecosystems. Here, we present evidence that the warming observed in recent decades has been accompanied by increased snow avalanche frequency in the Western Indian Himalayas. Using dendrogeomorphic techniques, we reconstruct the longest time series (150 y) of the occurrence and runout distances of snow avalanches that is currently available for the Himalayas. We apply a generalized linear autoregressive moving average model to demonstrate linkages between climate warming and the observed increase in the incidence of snow avalanches. Warming air temperatures in winter and early spring have indeed favored the wetting of snow and the formation of wet snow avalanches, which are now able to reach down to subalpine slopes, where they have high potential to cause damage. These findings contradict the intuitive notion that warming results in less snow, and thus lower avalanche activity, and have major implications for the Western Himalayan region, an area where human pressure is constantly increasing. Specifically, increasing traffic on a steadily expanding road network is calling for an immediate design of risk mitigation strategies and disaster risk policies to enhance climate change adaption in the wider study region. PMID:29535224

Mechanistic Lake Modeling to Understand and Predict Heterogeneous Responses to Climate Warming

NASA Astrophysics Data System (ADS)

Read, J. S.; Winslow, L. A.; Rose, K. C.; Hansen, G. J.

2016-12-01

Substantial warming has been documented for of hundreds globally distributed lakes, with likely impacts on ecosystem processes. Despite a clear pattern of widespread warming, thermal responses of individual lakes to climate change are often heterogeneous, with the warming rates of neighboring lakes varying across depths and among seasons. We aggregated temperature observations and parameterized mechanistic models for 9,000 lakes in the U.S. states of Minnesota, Wisconsin, and Michigan to examine broad-scale lake warming trends and among-lake diversity. Daily lake temperature profiles and ice-cover dynamics were simulated using the General Lake Model for the contemporary period (1979-2015) using drivers from the North American Land Data Assimilation System (NLDAS-2) and for contemporary and future periods (1980-2100) using downscaled data from six global circulation models driven by the Representative Climate Pathway 8.5 scenario. For the contemporary period, modeled vs observed summer mean surface temperatures had a root mean squared error of 0.98°C with modeled warming trends similar to observed trends. Future simulations under the extreme 8.5 scenario predicted a median lake summer surface warming rate of 0.57°C/decade until mid-century, with slower rates in the later half of the 21st century (0.35°C/decade). Modeling scenarios and analysis of field data suggest that the lake-specific properties of size, water clarity, and depth are strong controls on the sensitivity of lakes to climate change. For example, a simulated 1% annual decline in water clarity was sufficient to override the effects of climate warming on whole lake water temperatures in some - but not all - study lakes. Understanding heterogeneous lake responses to climate variability can help identify lake-specific features that influence resilience to climate change.

A new mechanism for warm-season precipitation response to global warming based on convection-permitting simulations

NASA Astrophysics Data System (ADS)

Dai, Aiguo; Rasmussen, Roy M.; Liu, Changhai; Ikeda, Kyoko; Prein, Andreas F.

2017-08-01

Climate models project increasing precipitation intensity but decreasing frequency as greenhouse gases increase. However, the exact mechanism for the frequency decrease remains unclear. Here we investigate this by analyzing hourly data from regional climate change simulations with 4 km grid spacing covering most of North America using the Weather Research and Forecasting model. The model was forced with present and future boundary conditions, with the latter being derived by adding the CMIP5 19-model ensemble mean changes to the ERA-interim reanalysis. The model reproduces well the observed seasonal and spatial variations in precipitation frequency and histograms, and the dry interval between rain events over the contiguous US. Results show that overall precipitation frequency indeed decreases during the warm season mainly due to fewer light-moderate precipitation (0.1 < P ≤ 2.0 mm/h) events, while heavy (2 < P ≤ 10 mm/h) to very heavy precipitation (P > 10 mm/h) events increase. Dry spells become longer and more frequent, together with a reduction in time-mean relative humidity (RH) in the lower troposphere during the warm season. The increased dry hours and decreased RH lead to a reduction in overall precipitation frequency and also for light-moderate precipitation events, while water vapor-induced increases in precipitation intensity and the positive latent heating feedback in intense storms may be responsible for the large increase in intense precipitation. The size of intense storms increases while their number decreases in the future climate, which helps explain the increase in local frequency of heavy precipitation. The results generally support a new hypothesis for future warm-season precipitation: each rainstorm removes ≥7% more moisture from the air per 1 K local warming, and surface evaporation and moisture advection take slightly longer than currently to replenish the depleted moisture before the next storm forms, leading to longer dry spells and

Evaluating the Dominant Components of Warming in Pliocene Climate Simulations

NASA Technical Reports Server (NTRS)

Hill, D. J.; Haywood, A. M.; Lunt, D. J.; Hunter, S. J.; Bragg, F. J.; Contoux, C.; Stepanek, C.; Sohl, L.; Rosenbloom, N. A.; Chan, W.-L.;

Lagging adaptation to warming climate in Arabidopsis thaliana.

PubMed

Wilczek, Amity M; Cooper, Martha D; Korves, Tonia M; Schmitt, Johanna

2014-06-03

If climate change outpaces the rate of adaptive evolution within a site, populations previously well adapted to local conditions may decline or disappear, and banked seeds from those populations will be unsuitable for restoring them. However, if such adaptational lag has occurred, immigrants from historically warmer climates will outperform natives and may provide genetic potential for evolutionary rescue. We tested for lagging adaptation to warming climate using banked seeds of the annual weed Arabidopsis thaliana in common garden experiments in four sites across the species' native European range: Valencia, Spain; Norwich, United Kingdom; Halle, Germany; and Oulu, Finland. Genotypes originating from geographic regions near the planting site had high relative fitness in each site, direct evidence for broad-scale geographic adaptation in this model species. However, genotypes originating in sites historically warmer than the planting site had higher average relative fitness than local genotypes in every site, especially at the northern range limit in Finland. This result suggests that local adaptive optima have shifted rapidly with recent warming across the species' native range. Climatic optima also differed among seasonal germination cohorts within the Norwich site, suggesting that populations occurring where summer germination is common may have greater evolutionary potential to persist under future warming. If adaptational lag has occurred over just a few decades in banked seeds of an annual species, it may be an important consideration for managing longer-lived species, as well as for attempts to conserve threatened populations through ex situ preservation.

Lagging adaptation to warming climate in Arabidopsis thaliana

PubMed Central

Wilczek, Amity M.; Cooper, Martha D.; Korves, Tonia M.; Schmitt, Johanna

2014-01-01

If climate change outpaces the rate of adaptive evolution within a site, populations previously well adapted to local conditions may decline or disappear, and banked seeds from those populations will be unsuitable for restoring them. However, if such adaptational lag has occurred, immigrants from historically warmer climates will outperform natives and may provide genetic potential for evolutionary rescue. We tested for lagging adaptation to warming climate using banked seeds of the annual weed Arabidopsis thaliana in common garden experiments in four sites across the species’ native European range: Valencia, Spain; Norwich, United Kingdom; Halle, Germany; and Oulu, Finland. Genotypes originating from geographic regions near the planting site had high relative fitness in each site, direct evidence for broad-scale geographic adaptation in this model species. However, genotypes originating in sites historically warmer than the planting site had higher average relative fitness than local genotypes in every site, especially at the northern range limit in Finland. This result suggests that local adaptive optima have shifted rapidly with recent warming across the species’ native range. Climatic optima also differed among seasonal germination cohorts within the Norwich site, suggesting that populations occurring where summer germination is common may have greater evolutionary potential to persist under future warming. If adaptational lag has occurred over just a few decades in banked seeds of an annual species, it may be an important consideration for managing longer-lived species, as well as for attempts to conserve threatened populations through ex situ preservation. PMID:24843140

Increasing ENSO-Driven Drought and Wildfire Risks in a Warming Climate

NASA Astrophysics Data System (ADS)

Fasullo, J.; Otto-Bliesner, B. L.; Stevenson, S.

2015-12-01

ENSO-related teleconnections occurring in the transient climate states of the 20th and 21st centuries are examined using the NCAR CESM1-CAM5 Large Ensemble (LE). A focus is given to quantifying the changing nature of related variability in a warming climate, the statistical robustness of which is enhanced by the numerous members of the LE (presently ~40). It is found that while the dynamical components of ENSO's teleconnections weaken considerably in a warming world, associated variability over land is in many cases sustained by changes in the background state, such as for rainfall due to the background rise in specific humidity. In some fields, particularly those associated with associated with thermal stress (e.g. drought and wildfire), ENSO-related variance increases dramatically. This, combined with the fact that ENSO variance itself increases in a warming climate in the LE, contributes to dramatic projected increases in ENSO-driven drought and wildfire risks in a warming world.

Emerging Stress and Relative Resiliency of Giant Sequoia Groves Experiencing Multiyear Dry Periods in a Warming Climate

NASA Astrophysics Data System (ADS)

Su, Yanjun; Bales, Roger C.; Ma, Qin; Nydick, Koren; Ray, Ram L.; Li, Wenkai; Guo, Qinghua

2017-11-01

The relative greenness and wetness of Giant Sequoia (Sequoiadendron giganteum) groves and the surrounding Sierra Nevada, California forests were investigated using patterns in vegetation indices from Landsat imagery for the period 1985-2015. Vegetation greenness (normalized difference vegetation index) and thus forest biomass in groves increased by about 6% over that 30 year period, suggesting a 10% increase in evapotranspiration. No significant change in the surrounding nongrove forest was observed. In this period, local temperature measurements showed an increase of about 2.2°C. The wetness of groves (normalized difference wetness index) showed no overall long-term trend but responded to changes in annual water-year precipitation and temperature. The long-term trends of grove greenness and wetness varied by elevation, with the lower rain-snow transition elevation zone (1,700-2,100 m) marking a change from an increasing trend at lower elevations to a decreasing trend at higher elevations. The 2011-2015 drought brought an unprecedented drop in grove wetness, over 5 times the 1985-2010 standard deviation, and wetness in SEGI groves dropped 50% more than in nongrove areas. Overall, the wetness and greenness of SEGI groves showed a larger response to the warming climate and drought than nongrove areas. The influence of droughts on the wetness of SEGI groves reflected effects of both the multidecadal increase in forest biomass and the effects of warmer drought-year temperatures on the evaporative demand of current grove vegetation, plus sufficient regolith water storage of rain and snowmelt to sustain that vegetation through seasonal and multiyear dry periods.

Daytime warming has stronger negative effects on soil nematodes than night-time warming.

PubMed

Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

2017-03-07

Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming.

Daytime warming has stronger negative effects on soil nematodes than night-time warming.

PubMed

Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

2017-03-20

Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming.

Daytime warming has stronger negative effects on soil nematodes than night-time warming

PubMed Central

Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

2017-01-01

Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming. PMID:28317914

Daytime warming has stronger negative effects on soil nematodes than night-time warming

NASA Astrophysics Data System (ADS)

Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

2017-03-01

Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming.

Future warming patterns linked to today’s climate variability

DOE PAGES

Dai, Aiguo

2016-01-11

The reliability of model projections of greenhouse gas (GHG)-induced future climate change is often assessed based on models’ ability to simulate the current climate, but there has been little evidence that connects the two. In fact, this practice has been questioned because the GHG-induced future climate change may involve additional physical processes that are not important for the current climate. Here I show that the spatial patterns of the GHG-induced future warming in the 21 st century is highly correlated with the patterns of the year-to-year variations of surface air temperature for today’s climate, with areas of larger variations duringmore » 1950–1979 having more GHG-induced warming in the 21 st century in all climate models. Such a relationship also exists in other climate fields such as atmospheric water vapor, and it is evident in observed temperatures from 1950–2010. The results suggest that many physical processes may work similarly in producing the year-to-year climate variations in the current climate and the GHG-induced long-term changes in the 21 st century in models and in the real world. Furthermore, they support the notion that models that simulate present-day climate variability better are likely to make more reliable predictions of future climate change.« less

Future warming patterns linked to today’s climate variability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Aiguo

The reliability of model projections of greenhouse gas (GHG)-induced future climate change is often assessed based on models’ ability to simulate the current climate, but there has been little evidence that connects the two. In fact, this practice has been questioned because the GHG-induced future climate change may involve additional physical processes that are not important for the current climate. Here I show that the spatial patterns of the GHG-induced future warming in the 21 st century is highly correlated with the patterns of the year-to-year variations of surface air temperature for today’s climate, with areas of larger variations duringmore » 1950–1979 having more GHG-induced warming in the 21 st century in all climate models. Such a relationship also exists in other climate fields such as atmospheric water vapor, and it is evident in observed temperatures from 1950–2010. The results suggest that many physical processes may work similarly in producing the year-to-year climate variations in the current climate and the GHG-induced long-term changes in the 21 st century in models and in the real world. Furthermore, they support the notion that models that simulate present-day climate variability better are likely to make more reliable predictions of future climate change.« less

Nonlinear climate sensitivity and its implications for future greenhouse warming.

PubMed

Friedrich, Tobias; Timmermann, Axel; Tigchelaar, Michelle; Elison Timm, Oliver; Ganopolski, Andrey

2016-11-01

Global mean surface temperatures are rising in response to anthropogenic greenhouse gas emissions. The magnitude of this warming at equilibrium for a given radiative forcing-referred to as specific equilibrium climate sensitivity ( S )-is still subject to uncertainties. We estimate global mean temperature variations and S using a 784,000-year-long field reconstruction of sea surface temperatures and a transient paleoclimate model simulation. Our results reveal that S is strongly dependent on the climate background state, with significantly larger values attained during warm phases. Using the Representative Concentration Pathway 8.5 for future greenhouse radiative forcing, we find that the range of paleo-based estimates of Earth's future warming by 2100 CE overlaps with the upper range of climate simulations conducted as part of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Furthermore, we find that within the 21st century, global mean temperatures will very likely exceed maximum levels reconstructed for the last 784,000 years. On the basis of temperature data from eight glacial cycles, our results provide an independent validation of the magnitude of current CMIP5 warming projections.

Nonlinear climate sensitivity and its implications for future greenhouse warming

PubMed Central

Friedrich, Tobias; Timmermann, Axel; Tigchelaar, Michelle; Elison Timm, Oliver; Ganopolski, Andrey

2016-01-01

Global mean surface temperatures are rising in response to anthropogenic greenhouse gas emissions. The magnitude of this warming at equilibrium for a given radiative forcing—referred to as specific equilibrium climate sensitivity (S)—is still subject to uncertainties. We estimate global mean temperature variations and S using a 784,000-year-long field reconstruction of sea surface temperatures and a transient paleoclimate model simulation. Our results reveal that S is strongly dependent on the climate background state, with significantly larger values attained during warm phases. Using the Representative Concentration Pathway 8.5 for future greenhouse radiative forcing, we find that the range of paleo-based estimates of Earth’s future warming by 2100 CE overlaps with the upper range of climate simulations conducted as part of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Furthermore, we find that within the 21st century, global mean temperatures will very likely exceed maximum levels reconstructed for the last 784,000 years. On the basis of temperature data from eight glacial cycles, our results provide an independent validation of the magnitude of current CMIP5 warming projections. PMID:28861462

Potential evapotranspiration and continental drying

USGS Publications Warehouse

Milly, Paul C.D.; Dunne, Krista A.

2016-01-01

By various measures (drought area and intensity, climatic aridity index, and climatic water deficits), some observational analyses have suggested that much of the Earth’s land has been drying during recent decades, but such drying seems inconsistent with observations of dryland greening and decreasing pan evaporation. ‘Offline’ analyses of climate-model outputs from anthropogenic climate change (ACC) experiments portend continuation of putative drying through the twenty-first century, despite an expected increase in global land precipitation. A ubiquitous increase in estimates of potential evapotranspiration (PET), driven by atmospheric warming, underlies the drying trends, but may be a methodological artefact. Here we show that the PET estimator commonly used (the Penman–Monteith PET for either an open-water surface or a reference crop) severely overpredicts the changes in non-water-stressed evapotranspiration computed in the climate models themselves in ACC experiments. This overprediction is partially due to neglect of stomatal conductance reductions commonly induced by increasing atmospheric CO2 concentrations in climate models. Our findings imply that historical and future tendencies towards continental drying, as characterized by offline-computed runoff, as well as other PET-dependent metrics, may be considerably weaker and less extensive than previously thought.

Varying selection differential throughout the climatic range of Norway spruce in Central Europe.

PubMed

Kapeller, Stefan; Dieckmann, Ulf; Schueler, Silvio

2017-01-01

Predicting species distribution changes in global warming requires an understanding of how climatic constraints shape the genetic variation of adaptive traits and force local adaptations. To understand the genetic capacity of Norway spruce populations in Central Europe, we analyzed the variation in tree heights at the juvenile stage in common garden experiments established from the species' warm-dry to cold-moist distribution limits. We report the following findings: First, 47% of the total tree height variation at trial sites is attributable to the tree populations irrespective of site climate. Second, tree height variation within populations is higher at cold-moist trial sites than at warm-dry sites and higher within populations originating from cold-moist habitats than from warm-dry habitats. Third, for tree ages of 7-15 years, the variation within populations increases at cold-moist trial sites, whereas it remains constant at warm-dry sites. Fourth, tree height distributions are right-skewed at cold-moist trial sites, whereas they are nonskewed, but platykurtic at warm-dry sites. Our results suggest that in cold environments, climatic conditions impose stronger selection and probably restrict the distribution of spruce, whereas at the warm distribution limit, the species' realized niche might rather be controlled by external drivers, for example, forest insects.

Analysis of Solar Chimneys in Different Climate Zones - Case of Social Housing in Ecuador

NASA Astrophysics Data System (ADS)

Godoy-Vaca, Luis; Almaguer, Manuel; Martínez-Gómez, Javier; Lobato, Andrea; Palme, Massimo

2017-10-01

The aim of this research is to simulate the performance of a solar chimney located in different macro-zones in Ecuador. The proposed solar chimney model was simulated using a python script in order to predict the temperature distribution and the mass flow over time. The results obtained were firstly compared with experimental data for dry-warm climate. Then, the model was evaluated and tested in real weather conditions: dry-warm, moist-warm and rainy-cold. In addition, the assumed chimney dimensions were chosen according to the literature for the studied conditions. In spite of evaluating the best nightly ventilation, different chimney wall materials were tested: solid brick, common brick and reinforced concrete. The results showed that concrete in a dry-warm climate, a metallic layer on the gap with solid brick in a moist-warm climate and reinforced concrete in a rainy cold climate used for the absorbent wall improve the thermal inertia of the social housing.

Global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time

Treesearch

Sarah C. Elmendorf; Gregory H.R. Henry; Robert D. Hollister; Robert G. Björk; Anne D. Bjorkman; Terry V. Callaghan; [and others] NO-VALUE; William Gould; Joel Mercado

2012-01-01

Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty...

Permafrost carbon-climate feedbacks accelerate global warming.

PubMed

Koven, Charles D; Ringeval, Bruno; Friedlingstein, Pierre; Ciais, Philippe; Cadule, Patricia; Khvorostyanov, Dmitry; Krinner, Gerhard; Tarnocai, Charles

2011-09-06

Permafrost soils contain enormous amounts of organic carbon, which could act as a positive feedback to global climate change due to enhanced respiration rates with warming. We have used a terrestrial ecosystem model that includes permafrost carbon dynamics, inhibition of respiration in frozen soil layers, vertical mixing of soil carbon from surface to permafrost layers, and CH(4) emissions from flooded areas, and which better matches new circumpolar inventories of soil carbon stocks, to explore the potential for carbon-climate feedbacks at high latitudes. Contrary to model results for the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4), when permafrost processes are included, terrestrial ecosystems north of 60°N could shift from being a sink to a source of CO(2) by the end of the 21st century when forced by a Special Report on Emissions Scenarios (SRES) A2 climate change scenario. Between 1860 and 2100, the model response to combined CO(2) fertilization and climate change changes from a sink of 68 Pg to a 27 + -7 Pg sink to 4 + -18 Pg source, depending on the processes and parameter values used. The integrated change in carbon due to climate change shifts from near zero, which is within the range of previous model estimates, to a climate-induced loss of carbon by ecosystems in the range of 25 + -3 to 85 + -16 Pg C, depending on processes included in the model, with a best estimate of a 62 + -7 Pg C loss. Methane emissions from high-latitude regions are calculated to increase from 34 Tg CH(4)/y to 41-70 Tg CH(4)/y, with increases due to CO(2) fertilization, permafrost thaw, and warming-induced increased CH(4) flux densities partially offset by a reduction in wetland extent.

Climate warming and Bergmann's rule through time: is there any evidence?

PubMed Central

Teplitsky, Celine; Millien, Virginie

2014-01-01

Climate change is expected to induce many ecological and evolutionary changes. Among these is the hypothesis that climate warming will cause a reduction in body size. This hypothesis stems from Bergmann's rule, a trend whereby species exhibit a smaller body size in warmer climates, and larger body size under colder conditions in endotherms. The mechanisms behind this rule are still debated, and it is not clear whether Bergmann's rule can be extended to predict the effects of climate change through time. We reviewed the primary literature for evidence (i) of a decrease in body size in response to climate warming, (ii) that changing body size is an adaptive response and (iii) that these responses are evolutionary or plastic. We found weak evidence for changes in body size through time as predicted by Bergmann's rule. Only three studies investigated the adaptive nature of these size decreases. Of these, none reported evidence of selection for smaller size or of a genetic basis for the size change, suggesting that size decreases could be due to nonadaptive plasticity in response to changing environmental conditions. More studies are needed before firm conclusions can be drawn about the underlying causes of these changes in body size in response to a warming climate. PMID:24454554

Influence of Climate Warming on Arctic Mammals? New Insights from Ancient DNA Studies of the Collared Lemming Dicrostonyx torquatus

PubMed Central

Prost, Stefan; Smirnov, Nickolay; Fedorov, Vadim B.; Sommer, Robert S.; Stiller, Mathias; Nagel, Doris; Knapp, Michael; Hofreiter, Michael

2010-01-01

Background Global temperature increased by approximately half a degree (Celsius) within the last 150 years. Even this moderate warming had major impacts on Earth's ecological and biological systems, especially in the Arctic where the magnitude of abiotic changes even exceeds those in temperate and tropical biomes. Therefore, understanding the biological consequences of climate change on high latitudes is of critical importance for future conservation of the species living in this habitat. The past 25,000 years can be used as a model for such changes, as they were marked by prominent climatic changes that influenced geographical distribution, demographic history and pattern of genetic variation of many extant species. We sequenced ancient and modern DNA of the collared lemming (Dicrostonyx torquatus), which is a key species of the arctic biota, from a single site (Pymva Shor, Northern Pre Urals, Russia) to see if climate warming events after the Last Glacial Maximum had detectable effects on the genetic variation of this arctic rodent species, which is strongly associated with a cold and dry climate. Results Using three dimensional network reconstructions we found a dramatic decline in genetic diversity following the LGM. Model-based approaches such as Approximate Bayesian Computation and Markov Chain Monte Carlo based Bayesian inference show that there is evidence for a population decline in the collared lemming following the LGM, with the population size dropping to a minimum during the Greenland Interstadial 1 (Bølling/Allerød) warming phase at 14.5 kyrs BP. Conclusion Our results show that previous climate warming events had a strong influence on genetic diversity and population size of collared lemmings. Due to its already severely compromised genetic diversity a similar population reduction as a result of the predicted future climate change could completely abolish the remaining genetic diversity in this population. Local population extinctions of collared

Climate warming and disease risks for terrestrial and marine biota

USGS Publications Warehouse

Harvell, C.D.; Mitchell, C.E.; Ward, J.R.; Altizer, S.; Dobson, A.P.; Ostfeld, R.S.; Samuel, M.D.

2002-01-01

Infectious diseases can cause rapid population declines or species extinctions. Many pathogens of terrestrial and marine taxa are sensitive to temperature, rainfall, and humidity, creating synergisms that could affect biodiversity. Climate warming can increase pathogen development and survival rates, disease transmission, and host susceptibility. Although most host-parasite systems are predicted to experience more frequent or severe disease impacts with warming, a subset of pathogens might decline with warming, releasing hosts from disease. Recently, changes in El Niño–Southern Oscillation events have had a detectable influence on marine and terrestrial pathogens, including coral diseases, oyster pathogens, crop pathogens, Rift Valley fever, and human cholera. To improve our ability to predict epidemics in wild populations, it will be necessary to separate the independent and interactive effects of multiple climate drivers on disease impact.

Climate Warming and Disease Risks for Terrestrial and Marine Biota

NASA Astrophysics Data System (ADS)

Harvell, C. Drew; Mitchell, Charles E.; Ward, Jessica R.; Altizer, Sonia; Dobson, Andrew P.; Ostfeld, Richard S.; Samuel, Michael D.

2002-06-01

Infectious diseases can cause rapid population declines or species extinctions. Many pathogens of terrestrial and marine taxa are sensitive to temperature, rainfall, and humidity, creating synergisms that could affect biodiversity. Climate warming can increase pathogen development and survival rates, disease transmission, and host susceptibility. Although most host-parasite systems are predicted to experience more frequent or severe disease impacts with warming, a subset of pathogens might decline with warming, releasing hosts from disease. Recently, changes in El Niño-Southern Oscillation events have had a detectable influence on marine and terrestrial pathogens, including coral diseases, oyster pathogens, crop pathogens, Rift Valley fever, and human cholera. To improve our ability to predict epidemics in wild populations, it will be necessary to separate the independent and interactive effects of multiple climate drivers on disease impact.

Tree water dynamics in a drying and warming world

DOE PAGES

Grossiord, Charlotte; Sevanto, Sanna Annika; Borrego, Isaac Anthony; ...

2017-05-26

Disentangling the relative impacts of precipitation reduction and vapour pressure deficit ( VPD) on plant water dynamics and determining whether acclimation may influence these patterns in the future is an important challenge. Here, we report sap flux density ( FD), stomatal conductance ( Gs), hydraulic conductivity ( KL) and xylem anatomy in piñon pine ( Pinus edulis) and juniper ( Juniperus monosperma) trees subjected to five years of precipitation reduction, atmospheric warming (elevated VPD) and their combined effects. No acclimation occurred under precipitation reduction: lower Gs and FD were found for both species compared to ambient conditions. Warming reduced themore » sensibility of stomata to VPD for both species but resulted in the maintenance of Gs and FD to ambient levels only for piñon. For juniper, reduced soil moisture under warming negated benefits of stomatal adjustments and resulted in reduced FD, Gs and KL. Although reduced stomatal sensitivity to VPD also occurred under combined stresses, reductions in Gs, FD and KL took place to similar levels as under single stresses for both species. Here our results show that stomatal conductance adjustments to high VPD could minimize but not entirely prevent additive effects of warming and drying on water use and carbon acquisition of trees in semi-arid regions.« less

Tree water dynamics in a drying and warming world

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grossiord, Charlotte; Sevanto, Sanna Annika; Borrego, Isaac Anthony

Disentangling the relative impacts of precipitation reduction and vapour pressure deficit ( VPD) on plant water dynamics and determining whether acclimation may influence these patterns in the future is an important challenge. Here, we report sap flux density ( FD), stomatal conductance ( Gs), hydraulic conductivity ( KL) and xylem anatomy in piñon pine ( Pinus edulis) and juniper ( Juniperus monosperma) trees subjected to five years of precipitation reduction, atmospheric warming (elevated VPD) and their combined effects. No acclimation occurred under precipitation reduction: lower Gs and FD were found for both species compared to ambient conditions. Warming reduced themore » sensibility of stomata to VPD for both species but resulted in the maintenance of Gs and FD to ambient levels only for piñon. For juniper, reduced soil moisture under warming negated benefits of stomatal adjustments and resulted in reduced FD, Gs and KL. Although reduced stomatal sensitivity to VPD also occurred under combined stresses, reductions in Gs, FD and KL took place to similar levels as under single stresses for both species. Here our results show that stomatal conductance adjustments to high VPD could minimize but not entirely prevent additive effects of warming and drying on water use and carbon acquisition of trees in semi-arid regions.« less

Australian climate extremes at 1.5 °C and 2 °C of global warming

NASA Astrophysics Data System (ADS)

King, Andrew D.; Karoly, David J.; Henley, Benjamin J.

2017-06-01

To avoid more severe impacts from climate change, there is international agreement to strive to limit warming to below 1.5 °C. However, there is a lack of literature assessing climate change at 1.5 °C and the potential benefits in terms of reduced frequency of extreme events. Here, we demonstrate that existing model simulations provide a basis for rapid and rigorous analysis of the effects of different levels of warming on large-scale climate extremes, using Australia as a case study. We show that limiting warming to 1.5 °C, relative to 2 °C, would perceptibly reduce the frequency of extreme heat events in Australia. The Australian continent experiences a variety of high-impact climate extremes that result in loss of life, and economic and environmental damage. Events similar to the record-hot summer of 2012-2013 and warm seas associated with bleaching of the Great Barrier Reef in 2016 would be substantially less likely, by about 25% in both cases, if warming is kept to lower levels. The benefits of limiting warming on hydrometeorological extremes are less clear. This study provides a framework for analysing climate extremes at 1.5 °C global warming.

Influence of warm air-drying on enamel bond strength and surface free-energy of self-etch adhesives.

PubMed

Shiratsuchi, Koji; Tsujimoto, Akimasa; Takamizawa, Toshiki; Furuichi, Tetsuya; Tsubota, Keishi; Kurokawa, Hiroyasu; Miyazaki, Masashi

2013-08-01

We examined the effect of warm air-drying on the enamel bond strengths and the surface free-energy of three single-step self-etch adhesives. Bovine mandibular incisors were mounted in self-curing resin and then wet ground with #600 silicon carbide (SiC) paper. The adhesives were applied according to the instructions of the respective manufacturers and then dried in a stream of normal (23°C) or warm (37°C) air for 5, 10, and 20 s. After visible-light irradiation of the adhesives, resin composites were condensed into a mold and polymerized. Ten samples per test group were stored in distilled water at 37°C for 24 h and then the bond strengths were measured. The surface free-energies were determined by measuring the contact angles of three test liquids placed on the cured adhesives. The enamel bond strengths varied according to the air-drying time and ranged from 15.8 to 19.1 MPa. The trends for the bond strengths were different among the materials. The value of the γS⁺ component increased slightly when drying was performed with a stream of warm air, whereas that of the γS⁻ component decreased significantly. These data suggest that warm air-drying is essential to obtain adequate enamel bond strengths, although increasing the drying time did not significantly influence the bond strength. © 2013 Eur J Oral Sci.

The Role of Atmospheric Heating over the South China Sea and Western Pacific Regions in Modulating Asian Summer Climate under the Global Warming Background

NASA Astrophysics Data System (ADS)

He, B.

2015-12-01

Global warming is one of the most significant climate change signals at the earth's surface. However, the responses of monsoon precipitation to global warming show very distinct regional features, especially over the South China Sea (SCS) and surrounding regions during boreal summer. To understand the possible dynamics in these specific regions under the global warming background, the changes in atmospheric latent heating and their possible influences on global climate are investigated by both observational diagnosis and numerical sensitivity simulations. Results indicate that summertime latent heating has intensified in the SCS and western Pacific, accompanied by increased precipitation, cloud cover, lower-tropospheric convergence, and decreased sea level pressure. Sensitivity experiments show that middle and upper tropospheric heating causes an east-west feedback pattern between SCS-western Pacific and South Asia, which strengthens the South Asian High in the upper troposphere and moist convergence in the lower troposphere, consequently forcing a descending motion and adiabatic warming over continental South Asia and leading to a warm and dry climate. When air-sea interaction is considered, the simulation results are overall more similar to observations, and in particular the bias of precipitation over the Indian Ocean simulated by AGCMs has been reduced. The results highlight the important role of latent heating in adjusting the changes in sea surface temperature through atmospheric dynamics.

Modeling aspen responses to climatic warming and insect defoliation in western Canada

Treesearch

E. H. Ted Hogg

2001-01-01

Effects of climate change at three aspen sites in Saskatchewan were explored using a climate-driven model that includes insect defoliation. A simulated warming of 4-5 °C caused complete mortality due to drought at all three sites. A simulated warming of 2-2.5 °C caused complete mortality of aspen at the parkland site, while aspen growth at two boreal sites showed...

Large Impacts of Climatic Warming on Growth of Boreal Forests since 1960

PubMed Central

Kauppi, Pekka E.; Posch, Maximilian; Pirinen, Pentti

2014-01-01

Boreal forests are sensitive to climatic warming, because low temperatures hold back ecosystem processes, such as the mobilization of nitrogen in soils. A greening of the boreal landscape has been observed using remote sensing, and the seasonal amplitude of CO2 in the northern hemisphere has increased, indicating warming effects on ecosystem productivity. However, field observations on responses of ecosystem productivity have been lacking on a large sub-biome scale. Here we report a significant increase in the annual growth of boreal forests in Finland in response to climatic warming, especially since 1990. This finding is obtained by linking meteorological records and forest inventory data on an area between 60° and 70° northern latitude. An additional increase in growth has occurred in response to changes in other drivers, such as forest management, nitrogen deposition and/or CO2 concentration. A similar warming impact can be expected in the entire boreal zone, where warming takes place. Given the large size of the boreal biome – more than ten million km2– important climate feedbacks are at stake, such as the future carbon balance, transpiration and albedo. PMID:25383552

Large impacts of climatic warming on growth of boreal forests since 1960.

PubMed

Kauppi, Pekka E; Posch, Maximilian; Pirinen, Pentti

2014-01-01

Boreal forests are sensitive to climatic warming, because low temperatures hold back ecosystem processes, such as the mobilization of nitrogen in soils. A greening of the boreal landscape has been observed using remote sensing, and the seasonal amplitude of CO2 in the northern hemisphere has increased, indicating warming effects on ecosystem productivity. However, field observations on responses of ecosystem productivity have been lacking on a large sub-biome scale. Here we report a significant increase in the annual growth of boreal forests in Finland in response to climatic warming, especially since 1990. This finding is obtained by linking meteorological records and forest inventory data on an area between 60° and 70° northern latitude. An additional increase in growth has occurred in response to changes in other drivers, such as forest management, nitrogen deposition and/or CO2 concentration. A similar warming impact can be expected in the entire boreal zone, where warming takes place. Given the large size of the boreal biome - more than ten million km2- important climate feedbacks are at stake, such as the future carbon balance, transpiration and albedo.

Personal efficacy, the information environment, and attitudes toward global warming and climate change in the United States.

PubMed

Kellstedt, Paul M; Zahran, Sammy; Vedlitz, Arnold

2008-02-01

Despite the growing scientific consensus about the risks of global warming and climate change, the mass media frequently portray the subject as one of great scientific controversy and debate. And yet previous studies of the mass public's subjective assessments of the risks of global warming and climate change have not sufficiently examined public informedness, public confidence in climate scientists, and the role of personal efficacy in affecting global warming outcomes. By examining the results of a survey on an original and representative sample of Americans, we find that these three forces-informedness, confidence in scientists, and personal efficacy-are related in interesting and unexpected ways, and exert significant influence on risk assessments of global warming and climate change. In particular, more informed respondents both feel less personally responsible for global warming, and also show less concern for global warming. We also find that confidence in scientists has unexpected effects: respondents with high confidence in scientists feel less responsible for global warming, and also show less concern for global warming. These results have substantial implications for the interaction between scientists and the public in general, and for the public discussion of global warming and climate change in particular.

Environmental Progression: The Psychological Justification for Reframing Climate Change and Global Warming

NASA Astrophysics Data System (ADS)

Veldey, S. H.

2016-12-01

On-going research in climate science communication through environmental media has uncovered critical barriers to reducing denial and increasing agency in addressing the threat of climate change. Similar to framing of our changing environment as "global warming", the term "climate change" also fails to properly frame the most critical challenge our species has faced. In a set of preliminary studies, significant changes in climate crisis denial, both positive and negative, have resulted from different media messaging. Continuation of this research utilizes social judgement theory (SJT) to classify a broader spectrum of effective avenues for environmental communication. The specificity of the terms global warming and climate change limit inclusion of issues critical to understanding their impacts. Now that the masses know what climate change is, it's time to teach them what it means.

Warming experiments underpredict plant phenological responses to climate change

USGS Publications Warehouse

Wolkovich, Elizabeth M.; Cook, Benjamin I.; Allen, Jenica M.; Crimmins, Theresa M.; Betancourt, Julio L.; Travers, Steven E.; Pau, Stephanie; Regetz, James; Davies, T. Jonathan; Kraft, Nathan J.B.; Ault, Toby R.; Bolmgren, Kjell; Mazer, Susan J.; McCabe, Gregory J.; McGill, Brian J.; Parmesan, Camille; Salamin, Nicolas; Schwartz, Mark D.; Cleland, Elsa E.

2012-01-01

Warming experiments are increasingly relied on to estimate plant responses to global climate change. For experiments to provide meaningful predictions of future responses, they should reflect the empirical record of responses to temperature variability and recent warming, including advances in the timing of flowering and leafing. We compared phenology (the timing of recurring life history events) in observational studies and warming experiments spanning four continents and 1,634 plant species using a common measure of temperature sensitivity (change in days per degree Celsius). We show that warming experiments underpredict advances in the timing of flowering and leafing by 8.5-fold and 4.0-fold, respectively, compared with long-term observations. For species that were common to both study types, the experimental results did not match the observational data in sign or magnitude. The observational data also showed that species that flower earliest in the spring have the highest temperature sensitivities, but this trend was not reflected in the experimental data. These significant mismatches seem to be unrelated to the study length or to the degree of manipulated warming in experiments. The discrepancy between experiments and observations, however, could arise from complex interactions among multiple drivers in the observational data, or it could arise from remediable artefacts in the experiments that result in lower irradiance and drier soils, thus dampening the phenological responses to manipulated warming. Our results introduce uncertainty into ecosystem models that are informed solely by experiments and suggest that responses to climate change that are predicted using such models should be re-evaluated.

Warming Experiments Underpredict Plant Phenological Responses to Climate Change

NASA Technical Reports Server (NTRS)

Wolkovich, E. M.; Cook, B. I.; Allen, J. M.; Crimmins, T. M.; Betancourt, J. L.; Travers, S. E.; Pau, S.; Regetz, J.; Davies, T. J.; Kraft, N. J. B.;

Impacts on regional climate of an afforestation scenario under a +2°C global warming climate

NASA Astrophysics Data System (ADS)

Strada, Susanna; Noblet-Ducoudré Nathalie, de; Marc, Stéfanon

2017-04-01

Through surface-atmosphere interactions (SAI), land-use and land-cover changes (LULCCs) alter atmospheric conditions with effects on climate at different scales, from local/regional (a few ten kilometres) (Pielke et al., 2011) to global scales (a few hundred kilometres) (Mahmood et al., 2014). Focusing on the regional scale, in the context of climate change, LULCCs may either enhance or dampen climate impacts via changes in SAI they may initiate. Those LULCC-driven atmospheric impacts could in turn influence e.g. the functioning of terrestrial ecosystems, with consequences on mitigation and adaptation strategies. Despite LULCC impacts on regional climate are largely discussed in the literature, in Europe information is missing on LULCC impacts under future climate conditions on a country scale (Galos et al., 2015). The latest COPs have urged the scientific community to explore the impacts of reduced global warming (1.5°C to a +2°C) on the Earth system. LULCCs will be one major tool to achieve such targets. In this framework, we investigate impacts on regional climate of a modified landscape under a +2°C climatic scenario. To this purpose, we performed sensitivity studies over western Europe with a fully coupled land-atmosphere regional climate model, WRF-ORCHIDEE (Drobinski et al., 2012, Stefanon et al., 2014). A +2°C scenario was selected among those proposed by the "Impact2C" project (Vautard et al., 2014), and the afforested land-cover scenario proposed in the RCP4.5 is prescribed. We have chosen the maximum extent of forest RCP4.5 simulates for Europe at the end of the 21st century. WRF-ORCHIDEE is fed with boundary atmospheric conditions from the global climate model LMDZ for PD (1971-2000) and the +2°C warming period for the LMDZ model (2028-2057). Preliminary results over the target domain show that, under a +2°C global warming scenario, afforestation contributes by 2% to the total warming due to both climate change and LULCCs. During summer, the

Glacial changes in warm pool climate dominated by shelf exposure and ice sheet albedo

NASA Astrophysics Data System (ADS)

Di Nezio, P. N.; Tierney, J. E.; Otto-Bliesner, B. L.; Timmermann, A.; Bhattacharya, T.; Brady, E. C.; Rosenbloom, N. A.

2017-12-01

The mechanisms driving glacial-interglacial changes in the climate of the Indo-Pacific warm pool (IPWP) are unclear. We addressed this issue combining model simulations and paleoclimate reconstructions of the Last Glacial Maximum (LGM). Two drivers - the exposure of tropical shelves due to lower sea level and a monsoonal response to ice sheet albedo - explain the proxy-inferred patterns of hydroclimate change. Shelf exposure influences IPWP climate by weakening the ascending branch of the Walker circulation. This response is amplified by coupled interactions akin to the Bjerknes feedback involving a stronger sea-surface temperature (SST) gradient along the equatorial Indian Ocean (IO). Ice sheet albedo enhances the import of cold, dry air into the tropics, weakening the Afro-Asian monsoon system. This "ventilation" mechanism alters temperature contrasts between the Arabian Sea and surrounding land leading to further monsoon weakening. Additional simulations show that the altered SST patterns associated with these responses are essential for explaining the proxy-inferred changes. Together our results show that ice sheets are a first order driver of tropical climate on glacial-interglacial timescales. While glacial climates are not a straightforward analogue for the future, our finding of an active Bjerknes feedback deserves further attention in the context of future climate projections.

Tropical forest soil microbes and climate warming: An Andean-Amazon gradient and `SWELTR'

NASA Astrophysics Data System (ADS)

Nottingham, A.; Turner, B. L.; Fierer, N.; Whitaker, J.; Ostle, N. J.; McNamara, N. P.; Bardgett, R.; Silman, M.; Bååth, E.; Salinas, N.; Meir, P.

2017-12-01

Climate warming predicted for the tropics in the coming century will result in average temperatures under which no closed canopy forest exists today. There is, therefore, great uncertainty associated with the direction and magnitude of feedbacks between tropical forests and our future climate - especially relating to the response of soil microbes and the third of global soil carbon contained in tropical forests. While warming experiments are yet to be performed in tropical forests, natural temperature gradients are powerful tools to investigate temperature effects on soil microbes. Here we draw on studies from a 3.5 km elevation gradient - and 20oC mean annual temperature gradient - in Peruvian tropical forest, to investigate how temperature affects the structure of microbial communities, microbial metabolism, enzymatic activity and soil organic matter cycling. With decreased elevation, soil microbial diversity increased and community composition shifted, from taxa associated with oligotrophic towards copiotrophic traits. A key role for temperature in shaping these patterns was demonstrated by a soil translocation experiment, where temperature-manipulation altered the relative abundance of specific taxa. Functional implications of these community composition shifts were indicated by changes in enzyme activities, the temperature sensitivity of bacterial and fungal growth rates, and the presence of temperature-adapted iso-enzymes at different elevations. Studies from a Peruvian elevation transect indicated that soil microbial communities are adapted to long-term (differences with elevation) and short-term (translocation responses) temperature changes. These findings indicate the potential for adaptation of soil microbes in tropical soils to future climate warming. However, in order to evaluate the sensitivity of these processes to climate warming in lowland forests, in situ experimentation is required. Finally, we describe SWELTR (Soil Warming Experiment in Lowland

Impact of climate warming on upper layer of the Bering Sea

NASA Astrophysics Data System (ADS)

Lee, Hyun-Chul; Delworth, Thomas L.; Rosati, Anthony; Zhang, Rong; Anderson, Whit G.; Zeng, Fanrong; Stock, Charles A.; Gnanadesikan, Anand; Dixon, Keith W.; Griffies, Stephen M.

2013-01-01

The impact of climate warming on the upper layer of the Bering Sea is investigated by using a high-resolution coupled global climate model. The model is forced by increasing atmospheric CO2 at a rate of 1% per year until CO2 reaches double its initial value (after 70 years), after which it is held constant. In response to this forcing, the upper layer of the Bering Sea warms by about 2°C in the southeastern shelf and by a little more than 1°C in the western basin. The wintertime ventilation to the permanent thermocline weakens in the western Bering Sea. After CO2 doubling, the southeastern shelf of the Bering Sea becomes almost ice-free in March, and the stratification of the upper layer strengthens in May and June. Changes of physical condition due to the climate warming would impact the pre-condition of spring bio-productivity in the southeastern shelf.

Climate-induced warming of lakes can be either amplified or suppressed by trends in water clarity

USGS Publications Warehouse

Rose, Kevin C.; Winslow, Luke A.; Read, Jordan S.; Hansen, Gretchen J. A.

2016-01-01

Climate change is rapidly warming aquatic ecosystems including lakes and reservoirs. However, variability in lake characteristics can modulate how lakes respond to climate. Water clarity is especially important both because it influences the depth range over which heat is absorbed, and because it is changing in many lakes. Here, we show that simulated long-term water clarity trends influence how both surface and bottom water temperatures of lakes and reservoirs respond to climate change. Clarity changes can either amplify or suppress climate-induced warming, depending on lake depth and the direction of clarity change. Using a process-based model to simulate 1894 north temperate lakes from 1979 to 2012, we show that a scenario of decreasing clarity at a conservative yet widely observed rate of 0.92% yr−1 warmed surface waters and cooled bottom waters at rates comparable in magnitude to climate-induced warming. For lakes deeper than 6.5 m, decreasing clarity was sufficient to fully offset the effects of climate-induced warming on median whole-lake mean temperatures. Conversely, a scenario increasing clarity at the same rate cooled surface waters and warmed bottom waters relative to baseline warming rates. Furthermore, in 43% of lakes, increasing clarity more than doubled baseline bottom temperature warming rates. Long-term empirical observations of water temperature in lakes with and without clarity trends support these simulation results. Together, these results demonstrate that water clarity trends may be as important as rising air temperatures in determining how waterbodies respond to climate change.

Predicted effects of climate warming on the distribution of 50 stream fishes in Wisconsin, USA.

PubMed

Lyons, J; Stewart, J S; Mitro, M

2010-11-01

Summer air and stream water temperatures are expected to rise in the state of Wisconsin, U.S.A., over the next 50 years. To assess potential climate warming effects on stream fishes, predictive models were developed for 50 common fish species using classification-tree analysis of 69 environmental variables in a geographic information system. Model accuracy was 56·0-93·5% in validation tests. Models were applied to all 86 898 km of stream in the state under four different climate scenarios: current conditions, limited climate warming (summer air temperatures increase 1° C and water 0·8° C), moderate warming (air 3° C and water 2·4° C) and major warming (air 5° C and water 4° C). With climate warming, 23 fishes were predicted to decline in distribution (three to extirpation under the major warming scenario), 23 to increase and four to have no change. Overall, declining species lost substantially more stream length than increasing species gained. All three cold-water and 16 cool-water fishes and four of 31 warm-water fishes were predicted to decline, four warm-water fishes to remain the same and 23 warm-water fishes to increase in distribution. Species changes were predicted to be most dramatic in small streams in northern Wisconsin that currently have cold to cool summer water temperatures and are dominated by cold-water and cool-water fishes, and least in larger and warmer streams and rivers in southern Wisconsin that are currently dominated by warm-water fishes. Results of this study suggest that even small increases in summer air and water temperatures owing to climate warming will have major effects on the distribution of stream fishes in Wisconsin. © 2010 The Authors. Journal of Fish Biology © 2010 The Fisheries Society of the British Isles.

Different sensitivities of snowpacks to warming in Mediterranean climate mountain areas

NASA Astrophysics Data System (ADS)

López-Moreno, J. I.; Gascoin, S.; Herrero, J.; Sproles, E. A.; Pons, M.; Alonso-González, E.; Hanich, L.; Boudhar, A.; Musselman, K. N.; Molotch, N. P.; Sickman, J.; Pomeroy, J.

2017-07-01

In this study we quantified the sensitivity of snow to climate warming in selected mountain sites having a Mediterranean climate, including the Pyrenees in Spain and Andorra, the Sierra Nevada in Spain and California (USA), the Atlas in Morocco, and the Andes in Chile. Meteorological observations from high elevations were used to simulate the snow energy and mass balance (SEMB) and calculate its sensitivity to climate. Very different climate sensitivities were evident amongst the various sites. For example, reductions of 9%-19% and 6-28 days in the mean snow water equivalent (SWE) and snow duration, respectively, were found per °C increase. Simulated changes in precipitation (±20%) did not affect the sensitivities. The Andes and Atlas Mountains have a shallow and cold snowpack, and net radiation dominates the SEMB; and explains their relatively low sensitivity to climate warming. The Pyrenees and USA Sierra Nevada have a deeper and warmer snowpack, and sensible heat flux is more important in the SEMB; this explains the much greater sensitivities of these regions. Differences in sensitivity help explain why, in regions where climate models project relatively greater temperature increases and drier conditions by 2050 (such as the Spanish Sierra Nevada and the Moroccan Atlas Mountains), the decline in snow accumulation and duration is similar to other sites (such as the Pyrenees and the USA Sierra Nevada), where models project stable precipitation and more attenuated warming. The snowpack in the Andes (Chile) exhibited the lowest sensitivity to warming, and is expected to undergo only moderate change (a decrease of <12% in mean SWE, and a reduction of < 7 days in snow duration under RCP 4.5). Snow accumulation and duration in the other regions are projected to decrease substantially (a minimum of 40% in mean SWE and 15 days in snow duration) by 2050.

The rogue nature of hiatuses in a global warming climate

NASA Astrophysics Data System (ADS)

Sévellec, F.; Sinha, B.; Skliris, N.

2016-08-01

The nature of rogue events is their unlikelihood and the recent unpredicted decade-long slowdown in surface warming, the so-called hiatus, may be such an event. However, given decadal variability in climate, global surface temperatures were never expected to increase monotonically with increasing radiative forcing. Here surface air temperature from 20 climate models is analyzed to estimate the historical and future likelihood of hiatuses and "surges" (faster than expected warming), showing that the global hiatus of the early 21st century was extremely unlikely. A novel analysis of future climate scenarios suggests that hiatuses will almost vanish and surges will strongly intensify by 2100 under a "business as usual" scenario. For "CO2 stabilisation" scenarios, hiatus, and surge characteristics revert to typical 1940s values. These results suggest to study the hiatus of the early 21st century and future reoccurrences as rogue events, at the limit of the variability of current climate modelling capability.

Implications of climate change (global warming) for the healthcare system.

PubMed

Raffa, R B; Eltoukhy, N S; Raffa, K F

2012-10-01

Temperature-sensitive pathogenic species and their vectors and hosts are emerging in previously colder regions as a consequence of several factors, including global warming. As a result, an increasing number of people will be exposed to pathogens against which they have not previously needed defences. We illustrate this with a specific example of recent emergence of Cryptococcus gattii infections in more temperate climates. The outbreaks in more temperate climates of the highly virulent--but usually tropically restricted--C. gattii is illustrative of an anticipated growing challenge for the healthcare system. There is a need for preparedness by healthcare professionals in anticipation and for management of such outbreaks, including other infections whose recent increased prevalence in temperate climates can be at least partly associated with global warming. (Re)emergence of temperature-sensitive pathogenic species in more temperate climates will present new challenges for healthcare systems. Preparation for outbreaks should precede their occurrence. © 2012 Blackwell Publishing Ltd.

Agro-climate Projections for a Warming Alaska

NASA Astrophysics Data System (ADS)

Lader, R.; Walsh, J. E.; Bhatt, U. S.; Bieniek, P.

2017-12-01

In the context of greenhouse warming, agro-meteorological indices suggest widespread disruption to current food supply chains during the coming decades. Much of the western United States is projected to have more dry days, and the southern states are likely to experience greater plant heat stress. Considering these difficulties, it could become necessary for more northerly locations, including Alaska, to increase agricultural production to support local communities and offset supply shortages. This study employs multiple dynamically downscaled regional climate model simulations from the CMIP5 to investigate projected changes to agro-climate conditions across Alaska. The metric used here, the start-of-field operations index (SFO), identifies the date during which the sum of daily average temperature, starting from January 1st and excluding negative values, exceeds 200 ˚C. Using the current trajectory of greenhouse radiative forcing, RCP 8.5, this study indicates a doubling to 71,960 km2 of Alaska land area that meets the required thermal accumulation for crop production when comparing a historical period (1981-2010) to the future (2071-2100). The SFO shows a correlation coefficient of 0.91 with the independently produced green-up index for Fairbanks from 1981-2010. Among the land areas that currently reach the necessary thermal accumulation, there is a projected increase in growing season length (63-82 days), earlier date of last spring frost (28-48 days), and later date of first autumn frost (24-47 days) across the five USDA Census of Agriculture areas for Alaska. Both an average statewide decrease of annual frost days (71 fewer), and an increase in days with extreme warmth (28 more) are also projected.

Permafrost carbon-climate feedbacks accelerate global warming

PubMed Central

Koven, Charles D.; Ringeval, Bruno; Friedlingstein, Pierre; Ciais, Philippe; Cadule, Patricia; Khvorostyanov, Dmitry; Krinner, Gerhard; Tarnocai, Charles

2011-01-01

Permafrost soils contain enormous amounts of organic carbon, which could act as a positive feedback to global climate change due to enhanced respiration rates with warming. We have used a terrestrial ecosystem model that includes permafrost carbon dynamics, inhibition of respiration in frozen soil layers, vertical mixing of soil carbon from surface to permafrost layers, and CH4 emissions from flooded areas, and which better matches new circumpolar inventories of soil carbon stocks, to explore the potential for carbon-climate feedbacks at high latitudes. Contrary to model results for the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4), when permafrost processes are included, terrestrial ecosystems north of 60°N could shift from being a sink to a source of CO2 by the end of the 21st century when forced by a Special Report on Emissions Scenarios (SRES) A2 climate change scenario. Between 1860 and 2100, the model response to combined CO2 fertilization and climate change changes from a sink of 68 Pg to a 27 + -7 Pg sink to 4 + -18 Pg source, depending on the processes and parameter values used. The integrated change in carbon due to climate change shifts from near zero, which is within the range of previous model estimates, to a climate-induced loss of carbon by ecosystems in the range of 25 + -3 to 85 + -16 Pg C, depending on processes included in the model, with a best estimate of a 62 + -7 Pg C loss. Methane emissions from high-latitude regions are calculated to increase from 34 Tg CH4/y to 41–70 Tg CH4/y, with increases due to CO2 fertilization, permafrost thaw, and warming-induced increased CH4 flux densities partially offset by a reduction in wetland extent. PMID:21852573

Global warming without global mean precipitation increase?

PubMed Central

Salzmann, Marc

2016-01-01

Global climate models simulate a robust increase of global mean precipitation of about 1.5 to 2% per kelvin surface warming in response to greenhouse gas (GHG) forcing. Here, it is shown that the sensitivity to aerosol cooling is robust as well, albeit roughly twice as large. This larger sensitivity is consistent with energy budget arguments. At the same time, it is still considerably lower than the 6.5 to 7% K−1 decrease of the water vapor concentration with cooling from anthropogenic aerosol because the water vapor radiative feedback lowers the hydrological sensitivity to anthropogenic forcings. When GHG and aerosol forcings are combined, the climate models with a realistic 20th century warming indicate that the global mean precipitation increase due to GHG warming has, until recently, been completely masked by aerosol drying. This explains the apparent lack of sensitivity of the global mean precipitation to the net global warming recently found in observations. As the importance of GHG warming increases in the future, a clear signal will emerge. PMID:27386558

Global warming without global mean precipitation increase?

PubMed

Salzmann, Marc

2016-06-01

Global climate models simulate a robust increase of global mean precipitation of about 1.5 to 2% per kelvin surface warming in response to greenhouse gas (GHG) forcing. Here, it is shown that the sensitivity to aerosol cooling is robust as well, albeit roughly twice as large. This larger sensitivity is consistent with energy budget arguments. At the same time, it is still considerably lower than the 6.5 to 7% K(-1) decrease of the water vapor concentration with cooling from anthropogenic aerosol because the water vapor radiative feedback lowers the hydrological sensitivity to anthropogenic forcings. When GHG and aerosol forcings are combined, the climate models with a realistic 20th century warming indicate that the global mean precipitation increase due to GHG warming has, until recently, been completely masked by aerosol drying. This explains the apparent lack of sensitivity of the global mean precipitation to the net global warming recently found in observations. As the importance of GHG warming increases in the future, a clear signal will emerge.

Large extents of intensive land use limit community reorganization during climate warming.

PubMed

Oliver, Tom H; Gillings, Simon; Pearce-Higgins, James W; Brereton, Tom; Crick, Humphrey Q P; Duffield, Simon J; Morecroft, Michael D; Roy, David B

2017-06-01

Climate change is increasingly altering the composition of ecological communities, in combination with other environmental pressures such as high-intensity land use. Pressures are expected to interact in their effects, but the extent to which intensive human land use constrains community responses to climate change is currently unclear. A generic indicator of climate change impact, the community temperature index (CTI), has previously been used to suggest that both bird and butterflies are successfully 'tracking' climate change. Here, we assessed community changes at over 600 English bird or butterfly monitoring sites over three decades and tested how the surrounding land has influenced these changes. We partitioned community changes into warm- and cold-associated assemblages and found that English bird communities have not reorganized successfully in response to climate change. CTI increases for birds are primarily attributable to the loss of cold-associated species, whilst for butterflies, warm-associated species have tended to increase. Importantly, the area of intensively managed land use around monitoring sites appears to influence these community changes, with large extents of intensively managed land limiting 'adaptive' community reorganization in response to climate change. Specifically, high-intensity land use appears to exacerbate declines in cold-adapted bird and butterfly species, and prevent increases in warm-associated birds. This has broad implications for managing landscapes to promote climate change adaptation. © 2017 John Wiley & Sons Ltd.

Extreme Warming Challenges Sentinel Status of Kelp Forests as Indicators of Climate Change

NASA Astrophysics Data System (ADS)

Miller, R. J.; Reed, D.; Washburn, L.; Rassweiler, A.; Bell, T. W.; Harrer, S.

2016-12-01

The ecological effects of global warming are expected to be large, but are proving difficult and costly to measure. This has led to a growing interest in using sentinel species as early warning indicators of impending climate change effects on entire ecosystems, raising awareness of the importance of verifying that such conservation shortcuts have sound biological foundations. A recent large-scale warming event in the North Pacific Ocean of unprecedented magnitude and duration allowed us to evaluate the sentinel status of giant kelp, a coastal foundation species that thrives in cold, nutrient-rich waters and considered sensitive to warming. Here we show that giant kelp did not presage ecosystem effects of extreme warming off southern California despite its expected vulnerability. Fluctuations in the biomass of giant kelp, understory algae, invertebrates and fish remained within historical ranges despite 34 months of above average temperatures and below average nutrients. Sea stars and sea urchins were exceptions, plummeting due to disease outbreaks linked to the warming. Our results challenge the IPCC predictions about the vulnerability of kelp-dominated systems to extreme warming events and question their use as early indicators of climate change. The resilience of giant kelp to unprecedented warming not only questions our understanding of kelp ecology, but exposes the risk of relying on supposed sentinel species that are assumed to be very sensitive to climate change.

Paleoclimate diagnostics: consistent large-scale temperature responses in warm and cold climates

NASA Astrophysics Data System (ADS)

Izumi, Kenji; Bartlein, Patrick; Harrison, Sandy

2015-04-01

The CMIP5 model simulations of the large-scale temperature responses to increased raditative forcing include enhanced land-ocean contrast, stronger response at higher latitudes than in the tropics, and differential responses in warm and cool season climates to uniform forcing. Here we show that these patterns are also characteristic of CMIP5 model simulations of past climates. The differences in the responses over land as opposed to over the ocean, between high and low latitudes, and between summer and winter are remarkably consistent (proportional and nearly linear) across simulations of both cold and warm climates. Similar patterns also appear in historical observations and paleoclimatic reconstructions, implying that such responses are characteristic features of the climate system and not simple model artifacts, thereby increasing our confidence in the ability of climate models to correctly simulate different climatic states. We also show the possibility that a small set of common mechanisms control these large-scale responses of the climate system across multiple states.

New use of global warming potentials to compare cumulative and short-lived climate pollutants

NASA Astrophysics Data System (ADS)

Allen, Myles R.; Fuglestvedt, Jan S.; Shine, Keith P.; Reisinger, Andy; Pierrehumbert, Raymond T.; Forster, Piers M.

2016-08-01

Parties to the United Nations Framework Convention on Climate Change (UNFCCC) have requested guidance on common greenhouse gas metrics in accounting for Nationally determined contributions (NDCs) to emission reductions. Metric choice can affect the relative emphasis placed on reductions of `cumulative climate pollutants' such as carbon dioxide versus `short-lived climate pollutants' (SLCPs), including methane and black carbon. Here we show that the widely used 100-year global warming potential (GWP100) effectively measures the relative impact of both cumulative pollutants and SLCPs on realized warming 20-40 years after the time of emission. If the overall goal of climate policy is to limit peak warming, GWP100 therefore overstates the importance of current SLCP emissions unless stringent and immediate reductions of all climate pollutants result in temperatures nearing their peak soon after mid-century, which may be necessary to limit warming to ``well below 2 °C'' (ref. ). The GWP100 can be used to approximately equate a one-off pulse emission of a cumulative pollutant and an indefinitely sustained change in the rate of emission of an SLCP. The climate implications of traditional CO2-equivalent targets are ambiguous unless contributions from cumulative pollutants and SLCPs are specified separately.

Valley floor climate observations from the McMurdo dry valleys, Antarctica, 1986-2000

USGS Publications Warehouse

Doran, P.T.; McKay, C.P.; Clow, G.D.; Dana, G.L.; Fountain, A.G.; Nylen, T.; Lyons, W.B.

2002-01-01

Climate observations from the McMurdo dry valleys, East Antarctica are presented from a network of seven valley floor automatic meteorological stations during the period 1986 to 2000. Mean annual temperatures ranged from -14.8??C to -30.0??C, depending on the site and period of measurement. Mean annual relative humidity is generally highest near the coast. Mean annual wind speed increases with proximity to the polar plateau. Site-to-site variation in mean annual solar flux and PAR is due to exposure of each station and changes over time are likely related to changes in cloudiness. During the nonsummer months, strong katabatic winds are frequent at some sites and infrequent at others, creating large variation in mean annual temperature owing to the warming effect of the winds. Katabatic wind exposure appears to be controlled to a large degree by the presence of colder air in the region that collects at low points and keeps the warm less dense katabatic flow from the ground. The strong influence of katabatic winds makes prediction of relative mean annual temperature based on geographical position (elevation and distance from the coast) alone, not possible. During the summer months, onshore winds dominate and warm as they progress through the valleys creating a strong linear relationship (r2 = 0.992) of increasing potential temperature with distance from the coast (0.09??C km-1). In contrast to mean annual temperature, summer temperature lends itself quite well to model predictions, and is used to construct a statistical model for predicting summer dry valley temperatures at unmonitored sites. Copyright 2002 by the American Geophysical Union.

Beyond a warming fingerprint: individualistic biogeographic responses to heterogeneous climate change in California

PubMed Central

Rapacciuolo, Giovanni; Maher, Sean P; Schneider, Adam C; Hammond, Talisin T; Jabis, Meredith D; Walsh, Rachel E; Iknayan, Kelly J; Walden, Genevieve K; Oldfather, Meagan F; Ackerly, David D; Beissinger, Steven R

2014-01-01

Understanding recent biogeographic responses to climate change is fundamental for improving our predictions of likely future responses and guiding conservation planning at both local and global scales. Studies of observed biogeographic responses to 20th century climate change have principally examined effects related to ubiquitous increases in temperature – collectively termed a warming fingerprint. Although the importance of changes in other aspects of climate – particularly precipitation and water availability – is widely acknowledged from a theoretical standpoint and supported by paleontological evidence, we lack a practical understanding of how these changes interact with temperature to drive biogeographic responses. Further complicating matters, differences in life history and ecological attributes may lead species to respond differently to the same changes in climate. Here, we examine whether recent biogeographic patterns across California are consistent with a warming fingerprint. We describe how various components of climate have changed regionally in California during the 20th century and review empirical evidence of biogeographic responses to these changes, particularly elevational range shifts. Many responses to climate change do not appear to be consistent with a warming fingerprint, with downslope shifts in elevation being as common as upslope shifts across a number of taxa and many demographic and community responses being inconsistent with upslope shifts. We identify a number of potential direct and indirect mechanisms for these responses, including the influence of aspects of climate change other than temperature (e.g., the shifting seasonal balance of energy and water availability), differences in each taxon's sensitivity to climate change, trophic interactions, and land-use change. Finally, we highlight the need to move beyond a warming fingerprint in studies of biogeographic responses by considering a more multifaceted view of climate

Midlatitude Summer Drying: An Underestimated Threat in CMIP5 Models?

NASA Astrophysics Data System (ADS)

Douville, H.; Plazzotta, M.

2017-10-01

Early assessments of the hydrological impacts of global warming suggested both an intensification of the global water cycle and an expansion of dry areas. Yet these alarming conclusions were challenged by a number of latter studies emphasizing the lack of evidence in observations and historical simulations, as well as the large uncertainties in climate projections from the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Here several aridity indices and a two-tier attribution strategy are used to demonstrate that a summer midlatitude drying has recently emerged over the northern continents, which is mainly attributable to anthropogenic climate change. This emerging signal is shown to be the harbinger of a long-term drying in the CMIP5 projections. Linear trends in the observed aridity indices can therefore be used as observational constraints and suggest that the projected midlatitude summer drying was underestimated by most CMIP5 models. Mitigating global warming therefore remains a priority to avoid dangerous impacts on global water and food security.

Low Elevation Riparian Environments: Warm-Climate Refugia for Conifers in the Great Basin, USA?

NASA Astrophysics Data System (ADS)

Millar, C.; Charlet, D. A.; Westfall, R. D.; Delany, D.

2015-12-01

The Great Basin, USA, contains hundreds of small to large mountain ranges. Many reach alpine elevations, which are separated from each other by low-elevation basins currently inhospitable to conifer growth. Many of these ranges support montane and subalpine conifer species that have affinities to the Sierra Nevada or Rocky Mountains, and from which these conifers migrated during cool periods of the Pleistocene. Under Holocene climates, the Great Basin geography became a terrestrial island-archipelago, wherein conifer populations are isolated among ranges, and inter-range migration is highly limited. During warm intervals of the Holocene, conifers would be expected to have migrated upslope following favorable conditions, and extirpation would be assumed to result from continued warming. Independent patterns, repeating across multiple species' distributions, however, suggest that refugia were present in these ranges during warm periods, and that low elevation environments below the current main distributions acted as climatic refugia. We hypothesize that cool, narrow, and north-aspect ravines, which during cool climates support persistent or seasonal creeks and deciduous riparian communities, become available as conifer habitat when warming climates desiccate creeks and deplete riparian species. We further speculate that cold-air drainage, reduced solar insolation, lower wind exposure, and higher water tables in these topographic positions support populations of montane and subalpine conifers even during warm climate intervals when high elevations are unfavorable for conifer persistence. On return to cool climates, low elevation refugia become sources for recolonizing higher slopes, and/or continue to persist as relictual populations. We present several lines of evidence supporting this hypothesis, and speculate that low-elevation, extramarginal riparian environments might act as climate refugia for Great Basin conifers in the future as well.

Global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time.

PubMed

Elmendorf, Sarah C; Henry, Gregory H R; Hollister, Robert D; Björk, Robert G; Bjorkman, Anne D; Callaghan, Terry V; Collier, Laura Siegwart; Cooper, Elisabeth J; Cornelissen, Johannes H C; Day, Thomas A; Fosaa, Anna Maria; Gould, William A; Grétarsdóttir, Járngerður; Harte, John; Hermanutz, Luise; Hik, David S; Hofgaard, Annika; Jarrad, Frith; Jónsdóttir, Ingibjörg Svala; Keuper, Frida; Klanderud, Kari; Klein, Julia A; Koh, Saewan; Kudo, Gaku; Lang, Simone I; Loewen, Val; May, Jeremy L; Mercado, Joel; Michelsen, Anders; Molau, Ulf; Myers-Smith, Isla H; Oberbauer, Steven F; Pieper, Sara; Post, Eric; Rixen, Christian; Robinson, Clare H; Schmidt, Niels Martin; Shaver, Gaius R; Stenström, Anna; Tolvanen, Anne; Totland, Orjan; Troxler, Tiffany; Wahren, Carl-Henrik; Webber, Patrick J; Welker, Jeffery M; Wookey, Philip A

2012-02-01

Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation - and associated ecosystem consequences - have the potential to be much greater than we have observed to date. © 2011 Blackwell Publishing Ltd/CNRS.

Thermal thresholds as predictors of seed dormancy release and germination timing: altitude-related risks from climate warming for the wild grapevine Vitis vinifera subsp. sylvestris.

PubMed

Orrù, Martino; Mattana, Efisio; Pritchard, Hugh W; Bacchetta, Gianluigi

2012-12-01

The importance of thermal thresholds for predicting seed dormancy release and germination timing under the present climate conditions and simulated climate change scenarios was investigated. In particular, Vitis vinifera subsp. sylvestris was investigated in four Sardinian populations over the full altitudinal range of the species (from approx. 100 to 800 m a.s.l). Dried and fresh seeds from each population were incubated in the light at a range of temperatures (10-25 and 25/10 °C), without any pre-treatment and after a warm (3 months at 25 °C) or a cold (3 months at 5 °C) stratification. A thermal time approach was then applied to the germination results for dried seeds and the seed responses were modelled according to the present climate conditions and two simulated scenarios of the Intergovernmental Panel on Climate Change (IPCC): B1 (+1·8 °C) and A2 (+3·4 °C). Cold stratification released physiological dormancy, while very few seeds germinated without treatments or after warm stratification. Fresh, cold-stratified seeds germinated significantly better (>80 %) at temperatures ≥20 °C than at lower temperatures. A base temperature for germination (T(b)) of 9·0-11·3 °C and a thermal time requirement for 50 % of germination (θ(50)) ranging from 33·6 °Cd to 68·6 °Cd were identified for non-dormant cold-stratified seeds, depending on the populations. This complex combination of thermal requirements for dormancy release and germination allowed prediction of field emergence from March to May under the present climatic conditions for the investigated populations. The thermal thresholds for seed germination identified in this study (T(b) and θ(50)) explained the differences in seed germination detected among populations. Under the two simulated IPCC scenarios, an altitude-related risk from climate warming is identified, with lowland populations being more threatened due to a compromised seed dormancy release and a narrowed seed germination window.

Tuning the climate sensitivity of a global model to match 20th Century warming

NASA Astrophysics Data System (ADS)

Mauritsen, T.; Roeckner, E.

2015-12-01

A climate models ability to reproduce observed historical warming is sometimes viewed as a measure of quality. Yet, for practical reasons historical warming cannot be considered a purely empirical result of the modelling efforts because the desired result is known in advance and so is a potential target of tuning. Here we explain how the latest edition of the Max Planck Institute for Meteorology Earth System Model (MPI-ESM1.2) atmospheric model (ECHAM6.3) had its climate sensitivity systematically tuned to about 3 K; the MPI model to be used during CMIP6. This was deliberately done in order to improve the match to observed 20th Century warming over the previous model generation (MPI-ESM, ECHAM6.1) which warmed too much and had a sensitivity of 3.5 K. In the process we identified several controls on model cloud feedback that confirm recently proposed hypotheses concerning trade-wind cumulus and high-latitude mixed-phase clouds. We then evaluate the model fidelity with centennial global warming and discuss the relative importance of climate sensitivity, forcing and ocean heat uptake efficiency in determining the response as well as possible systematic biases. The activity of targeting historical warming during model development is polarizing the modeling community with 35 percent of modelers stating that 20th Century warming was rated very important to decisive, whereas 30 percent would not consider it at all. Likewise, opinions diverge as to which measures are legitimate means for improving the model match to observed warming. These results are from a survey conducted in conjunction with the first WCRP Workshop on Model Tuning in fall 2014 answered by 23 modelers. We argue that tuning or constructing models to match observed warming to some extent is practically unavoidable, and as such, in many cases might as well be done explicitly. For modeling groups that have the capability to tune both their aerosol forcing and climate sensitivity there is now a unique

Isolating the Effects of the Warming Trend from the General Climate Change in Water Resources: California Case

NASA Astrophysics Data System (ADS)

Wang, J.; Yin, H.; Chung, F.

2008-12-01

While the population growth, the future land use change, and the desire for better environmental preservation and protection are adding up pressure on water resources management in California, California is facing an extra challenge of addressing potential climate change impacts on water supple and demand in California. The concerns on water facilities planning and flood control caused by climate change include modified precipitation patterns, changes in snow levels and runoff patterns due to increased air temperatures. Although long-term climate projections are largely uncertain, there appears to be a strong consistency in predicting the warming trend of future surface temperature, and the resulting shift in the seasonal patterns of runoff. However, projected changes in precipitation (wetting or drying), which control annual runoff, are far less certain. This paper attempts to separate the effects of warming trend from the effects of precipitation trend on water planning especially in California where reservoir operations are more sensitive to seasonal patterns of runoff than to the total annual runoff. The water resources systems planning model, CALSIM2, is used to evaluate climate change impact on water resource management in California. Rather than directly ingesting estimated streamflows from climate model projections into CALSIM2, a three step perturbation ratio method is proposed to introduce climate change impact into the planning model. Firstly, monthly perturbation ratio of projected monthly inflow to simulated historical monthly inflow is applied to observed historical monthly inflow to generate climate change inflows to major dams and reservoirs. To isolate the effects of warming trend on water resources, a further annual inflow adjustment is applied to the inflows generated in step one to preserve the volume of the observed annual inflow. To re-introduce the effects of precipitation trend on water resources, an additional inflow trend adjustment is

The capacity to cope with climate warming declines from temperate to tropical latitudes in two widely distributed Eucalyptus species.

PubMed

Drake, John E; Aspinwall, Michael J; Pfautsch, Sebastian; Rymer, Paul D; Reich, Peter B; Smith, Renee A; Crous, Kristine Y; Tissue, David T; Ghannoum, Oula; Tjoelker, Mark G

2015-01-01

As rapid climate warming creates a mismatch between forest trees and their home environment, the ability of trees to cope with warming depends on their capacity to physiologically adjust to higher temperatures. In widespread species, individual trees in cooler home climates are hypothesized to more successfully acclimate to warming than their counterparts in warmer climates that may approach thermal limits. We tested this prediction with a climate-shift experiment in widely distributed Eucalyptus tereticornis and E. grandis using provenances originating along a ~2500 km latitudinal transect (15.5-38.0°S) in eastern Australia. We grew 21 provenances in conditions approximating summer temperatures at seed origin and warmed temperatures (+3.5 °C) using a series of climate-controlled glasshouse bays. The effects of +3.5 °C warming strongly depended on home climate. Cool-origin provenances responded to warming through an increase in photosynthetic capacity and total leaf area, leading to enhanced growth of 20-60%. Warm-origin provenances, however, responded to warming through a reduction in photosynthetic capacity and total leaf area, leading to reduced growth of approximately 10%. These results suggest that there is predictable intraspecific variation in the capacity of trees to respond to warming; cool-origin taxa are likely to benefit from warming, while warm-origin taxa may be negatively affected. © 2014 John Wiley & Sons Ltd.

Recent Antarctic Peninsula warming relative to Holocene climate and ice-shelf history.

PubMed

Mulvaney, Robert; Abram, Nerilie J; Hindmarsh, Richard C A; Arrowsmith, Carol; Fleet, Louise; Triest, Jack; Sime, Louise C; Alemany, Olivier; Foord, Susan

2012-09-06

Rapid warming over the past 50 years on the Antarctic Peninsula is associated with the collapse of a number of ice shelves and accelerating glacier mass loss. In contrast, warming has been comparatively modest over West Antarctica and significant changes have not been observed over most of East Antarctica, suggesting that the ice-core palaeoclimate records available from these areas may not be representative of the climate history of the Antarctic Peninsula. Here we show that the Antarctic Peninsula experienced an early-Holocene warm period followed by stable temperatures, from about 9,200 to 2,500 years ago, that were similar to modern-day levels. Our temperature estimates are based on an ice-core record of deuterium variations from James Ross Island, off the northeastern tip of the Antarctic Peninsula. We find that the late-Holocene development of ice shelves near James Ross Island was coincident with pronounced cooling from 2,500 to 600 years ago. This cooling was part of a millennial-scale climate excursion with opposing anomalies on the eastern and western sides of the Antarctic Peninsula. Although warming of the northeastern Antarctic Peninsula began around 600 years ago, the high rate of warming over the past century is unusual (but not unprecedented) in the context of natural climate variability over the past two millennia. The connection shown here between past temperature and ice-shelf stability suggests that warming for several centuries rendered ice shelves on the northeastern Antarctic Peninsula vulnerable to collapse. Continued warming to temperatures that now exceed the stable conditions of most of the Holocene epoch is likely to cause ice-shelf instability to encroach farther southward along the Antarctic Peninsula.

Future drying of the southern Amazon and central Brazil

NASA Astrophysics Data System (ADS)

Yoon, J.; Zeng, N.; Cook, B.

2008-12-01

Recent climate modeling suggests that the Amazon rainforest could exhibit considerable dieback under future climate change, a prediction that has raised considerable interest as well as controversy. To determine the likelihood and causes of such changes, we analyzed the output of 15 models from the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC/AR4) and a dynamic vegetation model VEGAS driven by these climate output. Our results suggest that the core of the Amazon rainforest should remain largely stable. However, the periphery, notably the southern edge, is in danger of drying out, driven by two main processes. First, a decline in precipitation of 24% in the southern Amazon lengthens the dry season and reduces soil moisture, despite of an increase in precipitation during the wet season, due to the nonlinear response in hydrology and ecosystem dynamics. Two dynamical mechanisms may explain the lower dry season precipitation: (1) a stronger north-south tropical Atlantic sea surface temperature gradient; (2) a general subtropical drying under global warming when the dry season southern Amazon is under the control of the subtropical high pressure. Secondly, evaporation will increase due to the general warming, thus also reducing soil moisture. As a consequence, the median of the models projects a reduction of vegetation by 20%, and enhanced fire carbon flux by 10-15% in the southern Amazon, central Brazil, and parts of the Andean Mountains. Because the southern Amazon is also under intense human influence, the double pressure of deforestation and climate change may subject the region to dramatic changes in the 21st century.

[Treatment of patients with neuromuscular disease in a warm climate].

PubMed

Dahl, Arve; Skjeldal, Ola H; Simensen, Andreas; Dalen, Håkon E; Bråthen, Tone; Ahlvin, Petra; Svendsby, Ellen Kathrine; Sveinall, Anne; Fredriksen, Per Morten

2004-07-01

Several patient groups request treatment in a warm climate, in spite of the fact that the effects of such treatment are undocumented. 47 children and 40 adults with neuromuscular diseases were recruited, stratified according to sex, use or non-use of electric wheelchair, primary myopathy or hereditary neuropathy, and randomised into two adult and two children groups. The patients were treated in a rehabilitation centre, either on Lanzarote or in Norway. All patients were monitored with physical tests and questionnaires at the start of the study, at the end of the treatment period, after three months (all groups) and after six months (adults only). No significant differences in effect between the groups were found. In the warm climate, the adult patient group showed a statistically significant improvement regarding pain, quality of life, depression, and results of physical tests at the end of treatment. After three months, the improvement in physical tests was still present. Among adult patients treated in Norway, improvement in physical tests was statistically significant after three months, but not at the end of the treatment period. This study did not show a statistically significant difference between patients with various neuromuscular diseases treated in a warm climate compared to similar patients treated in Norway.

Reductions in labour capacity from heat stress under climate warming

NASA Astrophysics Data System (ADS)

Dunne, John P.; Stouffer, Ronald J.; John, Jasmin G.

2013-06-01

A fundamental aspect of greenhouse-gas-induced warming is a global-scale increase in absolute humidity. Under continued warming, this response has been shown to pose increasingly severe limitations on human activity in tropical and mid-latitudes during peak months of heat stress. One heat-stress metric with broad occupational health applications is wet-bulb globe temperature. We combine wet-bulb globe temperatures from global climate historical reanalysis and Earth System Model (ESM2M) projections with industrial and military guidelines for an acclimated individual's occupational capacity to safely perform sustained labour under environmental heat stress (labour capacity)--here defined as a global population-weighted metric temporally fixed at the 2010 distribution. We estimate that environmental heat stress has reduced labour capacity to 90% in peak months over the past few decades. ESM2M projects labour capacity reduction to 80% in peak months by 2050. Under the highest scenario considered (Representative Concentration Pathway 8.5), ESM2M projects labour capacity reduction to less than 40% by 2200 in peak months, with most tropical and mid-latitudes experiencing extreme climatological heat stress. Uncertainties and caveats associated with these projections include climate sensitivity, climate warming patterns, CO2 emissions, future population distributions, and technological and societal change.

Amplified Arctic warming by phytoplankton under greenhouse warming.

PubMed

Park, Jong-Yeon; Kug, Jong-Seong; Bader, Jürgen; Rolph, Rebecca; Kwon, Minho

2015-05-12

Phytoplankton have attracted increasing attention in climate science due to their impacts on climate systems. A new generation of climate models can now provide estimates of future climate change, considering the biological feedbacks through the development of the coupled physical-ecosystem model. Here we present the geophysical impact of phytoplankton, which is often overlooked in future climate projections. A suite of future warming experiments using a fully coupled ocean-atmosphere model that interacts with a marine ecosystem model reveals that the future phytoplankton change influenced by greenhouse warming can amplify Arctic surface warming considerably. The warming-induced sea ice melting and the corresponding increase in shortwave radiation penetrating into the ocean both result in a longer phytoplankton growing season in the Arctic. In turn, the increase in Arctic phytoplankton warms the ocean surface layer through direct biological heating, triggering additional positive feedbacks in the Arctic, and consequently intensifying the Arctic warming further. Our results establish the presence of marine phytoplankton as an important potential driver of the future Arctic climate changes.

Amplified Arctic warming by phytoplankton under greenhouse warming

PubMed Central

Park, Jong-Yeon; Kug, Jong-Seong; Bader, Jürgen; Rolph, Rebecca; Kwon, Minho

2015-01-01

Phytoplankton have attracted increasing attention in climate science due to their impacts on climate systems. A new generation of climate models can now provide estimates of future climate change, considering the biological feedbacks through the development of the coupled physical–ecosystem model. Here we present the geophysical impact of phytoplankton, which is often overlooked in future climate projections. A suite of future warming experiments using a fully coupled ocean−atmosphere model that interacts with a marine ecosystem model reveals that the future phytoplankton change influenced by greenhouse warming can amplify Arctic surface warming considerably. The warming-induced sea ice melting and the corresponding increase in shortwave radiation penetrating into the ocean both result in a longer phytoplankton growing season in the Arctic. In turn, the increase in Arctic phytoplankton warms the ocean surface layer through direct biological heating, triggering additional positive feedbacks in the Arctic, and consequently intensifying the Arctic warming further. Our results establish the presence of marine phytoplankton as an important potential driver of the future Arctic climate changes. PMID:25902494

Research Spotlight: Corals expanding poleward due to warming climate

NASA Astrophysics Data System (ADS)

Tretkoff, Ernie

2011-04-01

Corals are important organisms for ecosystems and are sensitive indicators of the effects of climate warming. While corals are bleaching and dying in tropical areas due to climate warming, a new study shows that in temperate areas they are expanding their range poleward as water temperatures increase. Yamano et al. used 80 years of records to study the range of corals around Japan. Sea surface temperatures have risen in these temperate areas during that time. They found that four of the nine species of coral they studied expanded their range northward since the 1930s, while none had its range shrink southward. The corals expanded northward as quickly as 14 kilometers per year. The study suggests that rapid modifications of temperate coastal ecosystems could be taking place. (Geophysical Research Letters, doi:10.1029/2010GL046474, 2011)

Developing resilient green roofs in a dry climate.

PubMed

Razzaghmanesh, M; Beecham, S; Brien, C J

2014-08-15

Living roofs are an emerging green infrastructure technology that can potentially be used to ameliorate both climate change and urban heat island effects. There is not much information regarding the design of green roofs for dry climates and so the aim of this study was to develop low maintenance and unfertilized green roofs for a dry climate. This paper describes the effects of four important elements of green roofs namely slope, depth, growing media and plant species and their possible interactions in terms of plant growth responses in a dry climate. Sixteen medium-scale green roofs were set up and monitored during a one year period. This experiment consisted of twelve vegetated platforms and four non-vegetated platforms as controls. The design for the experiment was a split-split-plot design in which the factors Slope (1° and 25°) and Depth (100mm, 300 mm) were randomized to the platforms (main plots). Root depth and volume, average height of plants, final dry biomass and ground cover, relative growth rate, final dry shoot-root ratio, water use efficiency and leaf succulence were studied during a twelve month period. The results showed little growth of the plants in media type A, whilst the growth was significant in both media types B and C. On average, a 90% survival rate of plants was observed. Also the growth indices indicated that some plants can grow efficiently in the harsh environment created by green roofs in a dry climate. The root growth pattern showed that retained water in the drainage layer is an alternative source of water for plants. It was also shown that stormwater can be used as a source of irrigation water for green roofs during six months of the year at the study site. In summary, mild sloping intensive systems containing media type C and planted with either Chrysocephalum apiculatum or Disphyma crassifolium showed the best performance. Copyright © 2014 Elsevier B.V. All rights reserved.

Role of Western Hemisphere Warm Pool in Rapid Climate Changes over the Western North Pacific

NASA Astrophysics Data System (ADS)

Kug, Jong-Seong; Park, Jae-Heung; An, Soon-Il

2017-04-01

Oceanic states over the western North Pacific (WNP), which is surrounded by heavily populated countries, are closely tied to the lives of the people in East Asia in regards to both climate and socioeconomics. As global warming continues, remarkable increases in sea surface temperature (SST) and sea surface height (SSH) have been observed in the WNP in recent decades. Here, we show that the SST increase in the western hemisphere warm pool (WHWP), which is the second largest warm pool on the globe, has contributed considerably to the rapid surface warming and sea level rise in the WNP via its remote teleconnection along the Pacific Intertropical Convergence Zone (ITCZ). State-of-the-art climate models strongly support the role of the WHWP not only on interannual time sales but also in long-term climate projections. We expect that understanding the processes initiated by the WHWP-SST could permit better forecasts of western North Pacific climate and the further development of the socioeconomics of East Asia.

The effects of climate changes on soil methane oxidation in a dry Arctic tundra

NASA Astrophysics Data System (ADS)

D'Imperio, Ludovica

2014-05-01

The effects of climate changes on soil methane oxidation in a dry Arctic tundra. Ludovica D'Imperio1, Anders Michelsen1, Christian J. Jørgensen1, Bo Elberling1 1Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Denmark At Northern latitudes climatic changes are predicted to be most pronounced resulting in increasing active layer depth and changes in growing season length, vegetation cover and nutrient cycling. As a consequence of increased temperature, large stocks of carbon stored in the permafrost-affected soils could become available for microbial transformations and under anoxic conditions result in increasing methane production affecting net methane (CH4) budget. Arctic tundra soils also serves as an important sink of atmospheric CH4 by microbial oxidation under aerobic conditions. While several process studies have documented the mechanisms behind both production and emissions of CH4 in arctic ecosystems, an important knowledge gap exists with respect to the in situ dynamics of microbial-driven uptake of CH4 in arctic dry lands which may be enhanced as a consequence of global warming and thereby counterbalancing CH4 emissions from Arctic wetlands. In-situ methane measurements were made in a dry Arctic tundra in Disko Island, Western Greenland, during the summer 2013 to assess the role of seasonal and inter-annual variations in temperatures and snow cover. The experimental set-up included snow fences installed in 2012, allowed investigations of the emissions of GHGs from soil under increased winter snow deposition and ambient field conditions. The soil fluxes of CH4 and CO2 were measured using closed chambers in manipulated plots with increased summer temperatures and shrub removal with or without increased winter precipitation. At the control plots, the averaged seasonal CH4 oxidation rates ranged between -0.05 mg CH4 m-2 hr-1 (end of August) and -0.32 mg CH4 m-2 hr-1 (end of June). In the

Potential Distribution Predicted for Rhynchophorus ferrugineus in China under Different Climate Warming Scenarios.

PubMed

Ge, Xuezhen; He, Shanyong; Wang, Tao; Yan, Wei; Zong, Shixiang

2015-01-01

As the primary pest of palm trees, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) has caused serious harm to palms since it first invaded China. The present study used CLIMEX 1.1 to predict the potential distribution of R. ferrugineus in China according to both current climate data (1981-2010) and future climate warming estimates based on simulated climate data for the 2020s (2011-2040) provided by the Tyndall Center for Climate Change Research (TYN SC 2.0). Additionally, the Ecoclimatic Index (EI) values calculated for different climatic conditions (current and future, as simulated by the B2 scenario) were compared. Areas with a suitable climate for R. ferrugineus distribution were located primarily in central China according to the current climate data, with the northern boundary of the distribution reaching to 40.1°N and including Tibet, north Sichuan, central Shaanxi, south Shanxi, and east Hebei. There was little difference in the potential distribution predicted by the four emission scenarios according to future climate warming estimates. The primary prediction under future climate warming models was that, compared with the current climate model, the number of highly favorable habitats would increase significantly and expand into northern China, whereas the number of both favorable and marginally favorable habitats would decrease. Contrast analysis of EI values suggested that climate change and the density of site distribution were the main effectors of the changes in EI values. These results will help to improve control measures, prevent the spread of this pest, and revise the targeted quarantine areas.

Potential Distribution Predicted for Rhynchophorus ferrugineus in China under Different Climate Warming Scenarios

PubMed Central

Ge, Xuezhen; He, Shanyong; Wang, Tao; Yan, Wei; Zong, Shixiang

2015-01-01

As the primary pest of palm trees, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) has caused serious harm to palms since it first invaded China. The present study used CLIMEX 1.1 to predict the potential distribution of R. ferrugineus in China according to both current climate data (1981–2010) and future climate warming estimates based on simulated climate data for the 2020s (2011–2040) provided by the Tyndall Center for Climate Change Research (TYN SC 2.0). Additionally, the Ecoclimatic Index (EI) values calculated for different climatic conditions (current and future, as simulated by the B2 scenario) were compared. Areas with a suitable climate for R. ferrugineus distribution were located primarily in central China according to the current climate data, with the northern boundary of the distribution reaching to 40.1°N and including Tibet, north Sichuan, central Shaanxi, south Shanxi, and east Hebei. There was little difference in the potential distribution predicted by the four emission scenarios according to future climate warming estimates. The primary prediction under future climate warming models was that, compared with the current climate model, the number of highly favorable habitats would increase significantly and expand into northern China, whereas the number of both favorable and marginally favorable habitats would decrease. Contrast analysis of EI values suggested that climate change and the density of site distribution were the main effectors of the changes in EI values. These results will help to improve control measures, prevent the spread of this pest, and revise the targeted quarantine areas. PMID:26496438

Disentangling the effects of a century of eutrophication and climate warming on freshwater lake fish assemblages

PubMed Central

Hansen, Gretchen J. A.; Bethke, Bethany J.; Cross, Timothy K.

2017-01-01

Eutrophication and climate warming are profoundly affecting fish in many freshwater lakes. Understanding the specific effects of these stressors is critical for development of effective adaptation and remediation strategies for conserving fish populations in a changing environment. Ecological niche models that incorporated the individual effects of nutrient concentration and climate were developed for 25 species of fish sampled in standard gillnet surveys from 1,577 Minnesota lakes. Lake phosphorus concentrations and climates were hindcasted to a pre-disturbance period of 1896–1925 using existing land use models and historical temperature data. Then historical fish assemblages were reconstructed using the ecological niche models. Substantial changes were noted when reconstructed fish assemblages were compared to those from the contemporary period (1981–2010). Disentangling the sometimes opposing, sometimes compounding, effects of eutrophication and climate warming was critical for understanding changes in fish assemblages. Reconstructed abundances of eutrophication-tolerant, warmwater taxa increased in prairie lakes that experienced significant eutrophication and climate warming. Eutrophication-intolerant, warmwater taxa abundance increased in forest lakes where primarily climate warming was the stressor. Coolwater fish declined in abundance in both ecoregions. Large changes in modeled abundance occurred when the effects of both climate and eutrophication operated in the same direction for some species. Conversely, the effects of climate warming and eutrophication operated in opposing directions for other species and dampened net changes in abundance. Quantifying the specific effects of climate and eutrophication will allow water resource managers to better understand how lakes have changed and provide expectations for sustainable fish assemblages in the future. PMID:28777816

How much would five trillion tonnes of carbon warm the climate?

NASA Astrophysics Data System (ADS)

Tokarska, Katarzyna Kasia; Gillett, Nathan P.; Weaver, Andrew J.; Arora, Vivek K.

2016-04-01

While estimates of fossil fuel reserves and resources are very uncertain, and the amount which could ultimately be burnt under a business as usual scenario would depend on prevailing economic and technological conditions, an amount of five trillion tonnes of carbon (5 EgC), corresponding to the lower end of the range of estimates of the total fossil fuel resource, is often cited as an estimate of total cumulative emissions in the absence of mitigation actions. The IPCC Fifth Assessment Report indicates that an approximately linear relationship between warming and cumulative carbon emissions holds only up to around 2 EgC emissions. It is typically assumed that at higher cumulative emissions the warming would tend to be less than that predicted by such a linear relationship, with the radiative saturation effect dominating the effects of positive carbon-climate feedbacks at high emissions, as predicted by simple carbon-climate models. We analyze simulations from four state-of-the-art Earth System Models (ESMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) and seven Earth System Models of Intermediate Complexity (EMICs), driven by the Representative Concentration Pathway 8.5 Extension scenario (RCP 8.5 Ext), which represents a very high emission scenario of increasing greenhouse gas concentrations in absence of climate mitigation policies. Our results demonstrate that while terrestrial and ocean carbon storage varies between the models, the CO2-induced warming continues to increase approximately linearly with cumulative carbon emissions even for higher levels of cumulative emissions, in all four ESMs. Five of the seven EMICs considered simulate a similarly linear response, while two exhibit less warming at higher cumulative emissions for reasons we discuss. The ESMs simulate global mean warming of 6.6-11.0°C, mean Arctic warming of 15.3-19.7°C, and mean regional precipitation increases and decreases by more than a factor of four, in response to 5Eg

Tropical Warm Semi-Arid Regions Expanding Over Temperate Latitudes In The Projected 21st Century

NASA Astrophysics Data System (ADS)

Rajaud, A.; de Noblet, N. I.

2015-12-01

Two billion people today live in drylands, where extreme climatic conditions prevail, and natural resources are limited. Drylands are expected to expand under several scenarios of climatic change. However, relevant adaptation strategies need to account for the aridity level: it conditions the equilibrium tree-cover density, ranging from deserts (hyper-arid) to dense savannas (sub-humid). Here we focus on the evolution of climatically defined warm semi-arid areas, where low-tree density covers can be maintained. We study the global repartition of these regions in the future and the bioclimatic shifts involved. We adopted a bioclimatological approach based on the Köppen climate classification. The warm semi-arid class is characterized by mean annual temperatures over 18°C and a rainfall-limitation criterion. A multi-model ensemble of CMIP5 projections for three representative concentration pathways was selected to analyze future conditions. The classification was first applied to the start, middle and end of the 20th and 21st centuries, in order to localize past and future warm semi-arid regions. Then, time-series for the classification were built to characterize trends and variability in the evolution of those regions. According to the CRU datasets, global expansion of the warm semi-arid area has already started (~+13%), following the global warming trend since the 1900s. This will continue according to all projections, most significantly so outside the tropical belt. Under the "business as usual" scenario, the global warm semi-arid area will increase by 30% and expand 12° poleward in the Northern Hemisphere, according to the multi-model mean. Drying drives the conversion from equatorial sub-humid conditions. Beyond 30° of latitude, cold semi-arid conditions become warm semi-arid through warming, and temperate conditions through combined warming and drying processes. Those various transitions may have drastic but also very distinct ecological and sociological

Mechanisms of elevation-dependent warming over complex terrain in high-resolution simulations of regional climate change

NASA Astrophysics Data System (ADS)

Minder, J. R.; Letcher, T.; Liu, C.

2016-12-01

Numerous observational and modeling studies have suggested that over mountainous terrain certain elevations can experience systematically enhanced rates of near-surface climate warming relative to the surrounding region, a phenomenon referred to as elevation-dependent warming (EDW). In many of these studies high-elevation locations were found to experience the fastest warming rates. A variety of physical mechanisms for EDW have been proposed but there is no consensus as to the dominant cause. We examine EDW in regional climate model (RCM) simulations with very high horizontal resolution (4-km horizontal grid). The simulation domain centers on the Rocky Mountains and intermountain west of the United States. Climate change simulations are conducted using the "pseudo global warming" framework to focus on the regional response to large-scale thermodynamic and radiative climate changes representative of mid-century anthropogenic global climate change. Substantial EDW is found in these simulations. Warming varies with elevation by up to 1°C depending on the season considered. The structure of EDW is only weakly sensitive to variations in horizontal grid spacing ranging from 4 to 36 km. The snow-albedo feedback (SAF) plays a major role in causing the simulated EDW. The elevation band of maximum warming varies seasonally, mostly following the margin of the seasonal snowpack where snow cover and albedo reductions are maximized under climate warming. Additional simulations where the SAF is artificially suppressed demonstrate that EDW variations of up to 0.6°C can be attributed to the SAF. Simulations with a suppressed SAF still exhibit EDW variations up to 0.8°C that must be explained by other mechanisms. This remaining EDW shows a near linear increase in warming with elevation in most months and does not appear to be inherited from the profile of large-scale free-tropospheric warming. Simple theoretical calculations suggest that the non-linear dependence of surface

Warm Rain Processes Over the Tropical Oceans and Implications on Climate Change

NASA Technical Reports Server (NTRS)

Lau, William K. M.; Wu, H. T.

2004-01-01

In this talk, we will first show results from TRMM regarding the characteristics of warm rains over the tropical oceans, and the dependence of rate of warm rain production on sea surface temperature. Results lead to the hypothesis that warm rain production efficiency, i.e., autoconversion, may be increased in a warm climate. We use the GEOS-II GCM to test this hypothesis. Our modeling results show that in a climate with increased rate of autoconversion, the total rain amount is increased, with warm rain contributing to a larger portion of the increase. The abundant rainout of warm precipitation at middle to low levels causes a reduction of high cloud cover due to the depletion of water available for ice-phase rain production. As a result, more isolated, but more intense penetrative convection develops. Results also show that increased autoconversion reduces the convective adjustment time scale tends, implying a faster recycling of atmospheric water. Most interestingly, the increased low level heating associated with warm rain leads to more energetic Madden and Julian oscillations in the tropics, with well-defined eastward propagation. While reducing the autoconversion leads to an abundant mix of westward and eastward tropical disturbance on daily to weekly time scales. The causes of the sensitivity of the dynamical regimes to the microphysics parameterization in the GCM will be discussed.

Experimental warming decreases arbuscular mycorrhizal fungal colonization in prairie plants along a Mediterranean climate gradient.

PubMed

Wilson, Hannah; Johnson, Bart R; Bohannan, Brendan; Pfeifer-Meister, Laurel; Mueller, Rebecca; Bridgham, Scott D

2016-01-01

Arbuscular mycorrhizal fungi (AMF) provide numerous services to their plant symbionts. Understanding climate change effects on AMF, and the resulting plant responses, is crucial for predicting ecosystem responses at regional and global scales. We investigated how the effects of climate change on AMF-plant symbioses are mediated by soil water availability, soil nutrient availability, and vegetation dynamics. We used a combination of a greenhouse experiment and a manipulative climate change experiment embedded within a Mediterranean climate gradient in the Pacific Northwest, USA to examine this question. Structural equation modeling (SEM) was used to determine the direct and indirect effects of experimental warming on AMF colonization. Warming directly decreased AMF colonization across plant species and across the climate gradient of the study region. Other positive and negative indirect effects of warming, mediated by soil water availability, soil nutrient availability, and vegetation dynamics, canceled each other out. A warming-induced decrease in AMF colonization would likely have substantial consequences for plant communities and ecosystem function. Moreover, predicted increases in more intense droughts and heavier rains for this region could shift the balance among indirect causal pathways, and either exacerbate or mitigate the negative, direct effect of increased temperature on AMF colonization.

Predicted effects of climate warming on the distribution of 50 stream fishes in Wisconsin, U.S.A.

USGS Publications Warehouse

Lyons, J.; Stewart, J.S.; Mitro, M.

2010-01-01

Summer air and stream water temperatures are expected to rise in the state of Wisconsin, U.S.A., over the next 50 years. To assess potential climate warming effects on stream fishes, predictive models were developed for 50 common fish species using classification-tree analysis of 69 environmental variables in a geographic information system. Model accuracy was 56.0-93.5% in validation tests. Models were applied to all 86 898 km of stream in the state under four different climate scenarios: current conditions, limited climate warming (summer air temperatures increase 1?? C and water 0.8?? C), moderate warming (air 3?? C and water 2.4?? C) and major warming (air 5?? C and water 4?? C). With climate warming, 23 fishes were predicted to decline in distribution (three to extirpation under the major warming scenario), 23 to increase and four to have no change. Overall, declining species lost substantially more stream length than increasing species gained. All three cold-water and 16 cool-water fishes and four of 31 warm-water fishes were predicted to decline, four warm-water fishes to remain the same and 23 warm-water fishes to increase in distribution. Species changes were predicted to be most dramatic in small streams in northern Wisconsin that currently have cold to cool summer water temperatures and are dominated by cold-water and cool-water fishes, and least in larger and warmer streams and rivers in southern Wisconsin that are currently dominated by warm-water fishes. Results of this study suggest that even small increases in summer air and water temperatures owing to climate warming will have major effects on the distribution of stream fishes in Wisconsin. ?? 2010 The Authors. Journal of Fish Biology ?? 2010 The Fisheries Society of the British Isles.

Predicted effects of climate warming on the distribution of 50 stream fishes in Wisconsin, U.S.A.

USGS Publications Warehouse

Stewart, Jana S.; Lyons, John D.; Matt Mitro,

2010-01-01

Summer air and stream water temperatures are expected to rise in the state of Wisconsin, U.S.A., over the next 50 years. To assess potential climate warming effects on stream fishes, predictive models were developed for 50 common fish species using classification-tree analysis of 69 environmental variables in a geographic information system. Model accuracy was 56·0–93·5% in validation tests. Models were applied to all 86 898 km of stream in the state under four different climate scenarios: current conditions, limited climate warming (summer air temperatures increase 1° C and water 0·8° C), moderate warming (air 3° C and water 2·4° C) and major warming (air 5° C and water 4° C). With climate warming, 23 fishes were predicted to decline in distribution (three to extirpation under the major warming scenario), 23 to increase and four to have no change. Overall, declining species lost substantially more stream length than increasing species gained. All three cold-water and 16 cool-water fishes and four of 31 warm-water fishes were predicted to decline, four warm-water fishes to remain the same and 23 warm-water fishes to increase in distribution. Species changes were predicted to be most dramatic in small streams in northern Wisconsin that currently have cold to cool summer water temperatures and are dominated by cold-water and cool-water fishes, and least in larger and warmer streams and rivers in southern Wisconsin that are currently dominated by warm-water fishes. Results of this study suggest that even small increases in summer air and water temperatures owing to climate warming will have major effects on the distribution of stream fishes in Wisconsin.

Effects of a warm compress containing menthol on the tear film in healthy subjects and dry eye patients

NASA Astrophysics Data System (ADS)

Arita, Reiko; Morishige, Naoyuki; Sakamoto, Ichiro; Imai, Natsuko; Shimada, Yuko; Igaki, Michihito; Suzuki, Atsushi; Itoh, Kouzo; Tsubota, Kazuo

2017-04-01

Menthol is thought to stimulate lacrimation via activation of cold-sensitive primary afferent neurons in the cornea. We evaluated a warm compress containing menthol as a potential treatment for dry eye by examining its effects on the tear film in healthy subjects (n = 20) and dry eye patients (n = 35). Disposable eyelid-warming steamers that either did (MH) or did not (HO) contain menthol were applied to one eye of each subject either once only for 10 min or repeatedly over 2 weeks. Single application of MH significantly increased tear meniscus volume (P = 8.6 × 10-5, P = 1.3 × 10-5) and tear film breakup time (P = 0.006, P = 0.002) as well as improved meibum condition in healthy subjects and dry eye patients, respectively. Repeated application of MH significantly increased tear meniscus volume (P = 0.004, P = 1.7 × 10-4) and tear film breakup time (P = 0.037, P = 0.010) in healthy subjects and dry eye patients, respectively. Repeated application of MH thus induced persistent increases in tear fluid volume and tear film stability in dry eye patients, suggesting that repeated use of a warm compress containing menthol is a potential novel treatment for dry eye disease.

Warming combined with more extreme precipitation regimes modifies the water sources used by trees.

PubMed

Grossiord, Charlotte; Sevanto, Sanna; Dawson, Todd E; Adams, Henry D; Collins, Adam D; Dickman, Lee T; Newman, Brent D; Stockton, Elizabeth A; McDowell, Nate G

2017-01-01

The persistence of vegetation under climate change will depend on a plant's capacity to exploit water resources. We analyzed water source dynamics in piñon pine and juniper trees subjected to precipitation reduction, atmospheric warming, and to both simultaneously. Piñon and juniper exhibited different and opposite shifts in water uptake depth in response to experimental stress and background climate over 3 yr. During a dry summer, juniper responded to warming with a shift to shallow water sources, whereas piñon pine responded to precipitation reduction with a shift to deeper sources in autumn. In normal and wet summers, both species responded to precipitation reduction, but juniper increased deep water uptake and piñon increased shallow water uptake. Shifts in the utilization of water sources were associated with reduced stomatal conductance and photosynthesis, suggesting that belowground compensation in response to warming and water reduction did not alleviate stress impacts for gas exchange. We have demonstrated that predicted climate change could modify water sources of trees. Warming impairs juniper uptake of deep sources during extended dry periods. Precipitation reduction alters the uptake of shallow sources following extended droughts for piñon. Shifts in water sources may not compensate for climate change impacts on tree physiology. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Conservation Planning for Coral Reefs Accounting for Climate Warming Disturbances.

PubMed

Magris, Rafael A; Heron, Scott F; Pressey, Robert L

2015-01-01

Incorporating warming disturbances into the design of marine protected areas (MPAs) is fundamental to developing appropriate conservation actions that confer coral reef resilience. We propose an MPA design approach that includes spatially- and temporally-varying sea-surface temperature (SST) data, integrating both observed (1985-2009) and projected (2010-2099) time-series. We derived indices of acute (time under reduced ecosystem function following short-term events) and chronic thermal stress (rate of warming) and combined them to delineate thermal-stress regimes. Coral reefs located on the Brazilian coast were used as a case study because they are considered a conservation priority in the southwestern Atlantic Ocean. We show that all coral reef areas in Brazil have experienced and are projected to continue to experience chronic warming, while acute events are expected to increase in frequency and intensity. We formulated quantitative conservation objectives for regimes of thermal stress. Based on these objectives, we then evaluated if/how they are achieved in existing Brazilian MPAs and identified priority areas where additional protection would reinforce resilience. Our results show that, although the current system of MPAs incorporates locations within some of our thermal-stress regimes, historical and future thermal refugia along the central coast are completely unprotected. Our approach is applicable to other marine ecosystems and adds to previous marine planning for climate change in two ways: (i) by demonstrating how to spatially configure MPAs that meet conservation objectives for warming disturbance using spatially- and temporally-explicit data; and (ii) by strategically allocating different forms of spatial management (MPA types) intended to mitigate warming impacts and also enhance future resistance to climate warming.

Conservation Planning for Coral Reefs Accounting for Climate Warming Disturbances

PubMed Central

Magris, Rafael A.; Heron, Scott F.; Pressey, Robert L.

2015-01-01

Incorporating warming disturbances into the design of marine protected areas (MPAs) is fundamental to developing appropriate conservation actions that confer coral reef resilience. We propose an MPA design approach that includes spatially- and temporally-varying sea-surface temperature (SST) data, integrating both observed (1985–2009) and projected (2010–2099) time-series. We derived indices of acute (time under reduced ecosystem function following short-term events) and chronic thermal stress (rate of warming) and combined them to delineate thermal-stress regimes. Coral reefs located on the Brazilian coast were used as a case study because they are considered a conservation priority in the southwestern Atlantic Ocean. We show that all coral reef areas in Brazil have experienced and are projected to continue to experience chronic warming, while acute events are expected to increase in frequency and intensity. We formulated quantitative conservation objectives for regimes of thermal stress. Based on these objectives, we then evaluated if/how they are achieved in existing Brazilian MPAs and identified priority areas where additional protection would reinforce resilience. Our results show that, although the current system of MPAs incorporates locations within some of our thermal-stress regimes, historical and future thermal refugia along the central coast are completely unprotected. Our approach is applicable to other marine ecosystems and adds to previous marine planning for climate change in two ways: (i) by demonstrating how to spatially configure MPAs that meet conservation objectives for warming disturbance using spatially- and temporally-explicit data; and (ii) by strategically allocating different forms of spatial management (MPA types) intended to mitigate warming impacts and also enhance future resistance to climate warming. PMID:26535586

Climate warming feedback from mountain birch forest expansion: reduced albedo dominates carbon uptake.

PubMed

de Wit, Heleen A; Bryn, Anders; Hofgaard, Annika; Karstensen, Jonas; Kvalevåg, Maria M; Peters, Glen P

2014-07-01

Expanding high-elevation and high-latitude forest has contrasting climate feedbacks through carbon sequestration (cooling) and reduced surface reflectance (warming), which are yet poorly quantified. Here, we present an empirically based projection of mountain birch forest expansion in south-central Norway under climate change and absence of land use. Climate effects of carbon sequestration and albedo change are compared using four emission metrics. Forest expansion was modeled for a projected 2.6 °C increase in summer temperature in 2100, with associated reduced snow cover. We find that the current (year 2000) forest line of the region is circa 100 m lower than its climatic potential due to land-use history. In the future scenarios, forest cover increased from 12% to 27% between 2000 and 2100, resulting in a 59% increase in biomass carbon storage and an albedo change from 0.46 to 0.30. Forest expansion in 2100 was behind its climatic potential, forest migration rates being the primary limiting factor. In 2100, the warming caused by lower albedo from expanding forest was 10 to 17 times stronger than the cooling effect from carbon sequestration for all emission metrics considered. Reduced snow cover further exacerbated the net warming feedback. The warming effect is considerably stronger than previously reported for boreal forest cover, because of the typically low biomass density in mountain forests and the large changes in albedo of snow-covered tundra areas. The positive climate feedback of high-latitude and high-elevation expanding forests with seasonal snow cover exceeds those of afforestation at lower elevation, and calls for further attention of both modelers and empiricists. The inclusion and upscaling of these climate feedbacks from mountain forests into global models is warranted to assess the potential global impacts. © 2013 John Wiley & Sons Ltd.

Free boundary models for mosquito range movement driven by climate warming.

PubMed

Bao, Wendi; Du, Yihong; Lin, Zhigui; Zhu, Huaiping

2018-03-01

As vectors, mosquitoes transmit numerous mosquito-borne diseases. Among the many factors affecting the distribution and density of mosquitoes, climate change and warming have been increasingly recognized as major ones. In this paper, we make use of three diffusive logistic models with free boundary in one space dimension to explore the impact of climate warming on the movement of mosquito range. First, a general model incorporating temperature change with location and time is introduced. In order to gain insights of the model, a simplified version of the model with the change of temperature depending only on location is analyzed theoretically, for which the dynamical behavior is completely determined and presented. The general model can be modified into a more realistic one of seasonal succession type, to take into account of the seasonal changes of mosquito movements during each year, where the general model applies only for the time period of the warm seasons of the year, and during the cold season, the mosquito range is fixed and the population is assumed to be in a hibernating status. For both the general model and the seasonal succession model, our numerical simulations indicate that the long-time dynamical behavior is qualitatively similar to the simplified model, and the effect of climate warming on the movement of mosquitoes can be easily captured. Moreover, our analysis reveals that hibernating enhances the chances of survival and successful spreading of the mosquitoes, but it slows down the spreading speed.

Beyond a warming fingerprint: individualistic biogeographic responses to heterogeneous climate change in California.

PubMed

Rapacciuolo, Giovanni; Maher, Sean P; Schneider, Adam C; Hammond, Talisin T; Jabis, Meredith D; Walsh, Rachel E; Iknayan, Kelly J; Walden, Genevieve K; Oldfather, Meagan F; Ackerly, David D; Beissinger, Steven R

2014-09-01

Understanding recent biogeographic responses to climate change is fundamental for improving our predictions of likely future responses and guiding conservation planning at both local and global scales. Studies of observed biogeographic responses to 20th century climate change have principally examined effects related to ubiquitous increases in temperature - collectively termed a warming fingerprint. Although the importance of changes in other aspects of climate - particularly precipitation and water availability - is widely acknowledged from a theoretical standpoint and supported by paleontological evidence, we lack a practical understanding of how these changes interact with temperature to drive biogeographic responses. Further complicating matters, differences in life history and ecological attributes may lead species to respond differently to the same changes in climate. Here, we examine whether recent biogeographic patterns across California are consistent with a warming fingerprint. We describe how various components of climate have changed regionally in California during the 20th century and review empirical evidence of biogeographic responses to these changes, particularly elevational range shifts. Many responses to climate change do not appear to be consistent with a warming fingerprint, with downslope shifts in elevation being as common as upslope shifts across a number of taxa and many demographic and community responses being inconsistent with upslope shifts. We identify a number of potential direct and indirect mechanisms for these responses, including the influence of aspects of climate change other than temperature (e.g., the shifting seasonal balance of energy and water availability), differences in each taxon's sensitivity to climate change, trophic interactions, and land-use change. Finally, we highlight the need to move beyond a warming fingerprint in studies of biogeographic responses by considering a more multifaceted view of climate

Elevation-dependent warming in global climate model simulations at high spatial resolution

NASA Astrophysics Data System (ADS)

Palazzi, Elisa; Mortarini, Luca; Terzago, Silvia; von Hardenberg, Jost

2018-06-01

The enhancement of warming rates with elevation, so-called elevation-dependent warming (EDW), is one of the regional, still not completely understood, expressions of global warming. Sentinels of climate and environmental changes, mountains have experienced more rapid and intense warming trends in the recent decades, leading to serious impacts on mountain ecosystems and downstream. In this paper we use a state-of-the-art Global Climate Model (EC-Earth) to investigate the impact of model spatial resolution on the representation of this phenomenon and to highlight possible differences in EDW and its causes in different mountain regions of the Northern Hemisphere. To this end we use EC-Earth climate simulations at five different spatial resolutions, from ˜ 125 to ˜ 16 km, to explore the existence and the driving mechanisms of EDW in the Colorado Rocky Mountains, the Greater Alpine Region and the Tibetan Plateau-Himalayas. Our results show that the more frequent EDW drivers in all regions and seasons are the changes in albedo and in downward thermal radiation and this is reflected in both daytime and nighttime warming. In the Tibetan Plateau-Himalayas and in the Greater Alpine Region, an additional driver is the change in specific humidity. We also find that, while generally the model shows no clear resolution dependence in its ability to simulate the existence of EDW in the different regions, specific EDW characteristics such as its intensity and the relative role of different driving mechanisms may be different in simulations performed at different spatial resolutions. Moreover, we find that the role of internal climate variability can be significant in modulating the EDW signal, as suggested by the spread found in the multi-member ensemble of the EC-Earth experiments which we use.

Climate warming and agricultural stressors interact to determine stream periphyton community composition.

PubMed

Piggott, Jeremy J; Salis, Romana K; Lear, Gavin; Townsend, Colin R; Matthaei, Christoph D

2015-01-01

Lack of knowledge about how the various drivers of global climate change will interact with multiple stressors already affecting ecosystems is the basis for great uncertainty in projections of future biological change. Despite concerns about the impacts of changes in land use, eutrophication and climate warming in running waters, the interactive effects of these stressors on stream periphyton are largely unknown. We manipulated nutrients (simulating agricultural runoff), deposited fine sediment (simulating agricultural erosion) (two levels each) and water temperature (eight levels, 0-6 °C above ambient) simultaneously in 128 streamside mesocosms. Our aim was to determine the individual and combined effects of the three stressors on the algal and bacterial constituents of the periphyton. All three stressors had pervasive individual effects, but in combination frequently produced synergisms at the population level and antagonisms at the community level. Depending on sediment and nutrient conditions, the effect of raised temperature frequently produced contrasting response patterns, with stronger or opposing effects when one or both stressors were augmented. Thus, warming tended to interact negatively with nutrients or sediment by weakening or reversing positive temperature effects or strengthening negative ones. Five classes of algal growth morphology were all affected in complex ways by raised temperature, suggesting that these measures may prove unreliable in biomonitoring programs in a warming climate. The evenness and diversity of the most abundant bacterial taxa increased with temperature at ambient but not with enriched nutrient levels, indicating that warming coupled with nutrient limitation may lead to a more evenly distributed bacterial community as temperatures rise. Freshwater management decisions that seek to avoid or mitigate the negative effects of agricultural land use on stream periphyton should be informed by knowledge of the interactive effects of

Plausible rice yield losses under future climate warming.

PubMed

Zhao, Chuang; Piao, Shilong; Wang, Xuhui; Huang, Yao; Ciais, Philippe; Elliott, Joshua; Huang, Mengtian; Janssens, Ivan A; Li, Tao; Lian, Xu; Liu, Yongwen; Müller, Christoph; Peng, Shushi; Wang, Tao; Zeng, Zhenzhong; Peñuelas, Josep

2016-12-19

Rice is the staple food for more than 50% of the world's population 1-3 . Reliable prediction of changes in rice yield is thus central for maintaining global food security. This is an extraordinary challenge. Here, we compare the sensitivity of rice yield to temperature increase derived from field warming experiments and three modelling approaches: statistical models, local crop models and global gridded crop models. Field warming experiments produce a substantial rice yield loss under warming, with an average temperature sensitivity of -5.2 ± 1.4% K -1 . Local crop models give a similar sensitivity (-6.3 ± 0.4% K -1 ), but statistical and global gridded crop models both suggest less negative impacts of warming on yields (-0.8 ± 0.3% and -2.4 ± 3.7% K -1 , respectively). Using data from field warming experiments, we further propose a conditional probability approach to constrain the large range of global gridded crop model results for the future yield changes in response to warming by the end of the century (from -1.3% to -9.3% K -1 ). The constraint implies a more negative response to warming (-8.3 ± 1.4% K -1 ) and reduces the spread of the model ensemble by 33%. This yield reduction exceeds that estimated by the International Food Policy Research Institute assessment (-4.2 to -6.4% K -1 ) (ref. 4). Our study suggests that without CO 2 fertilization, effective adaptation and genetic improvement, severe rice yield losses are plausible under intensive climate warming scenarios.

Recent climate extremes associated with the West Pacific Warming Mode

USGS Publications Warehouse

Funk, Chris; Hoell, Andrew

2017-01-01

Here we analyze empirical orthogonal functions (EOFs) of observations and a 30 member ensemble of Community Earth System Model version 1 (CESM1) simulations, and suggest that precipitation declines in the Greater Horn of Africa (GHA) and the northern Middle East/Southwestern Asia (NME/SWE: Iran, Iraq, Kuwait, Syria, Saudi Arabia north of 25°N, Israel, Jordan, and Lebanon) may be interpreted as an interaction between La Niña-like decadal variability and the West Pacific Warming Mode (WPWM). While they exhibit different SST patterns, warming of the Pacific cold tongue (ENSO) and warming of the western Pacific (WPWM) produce similar warm pool diabatic forcing, Walker circulation anomalies, and terrestrial teleconnections. CESM1 SST EOFs indicate that both La Niña-like WPWM warming and El Niño-like east Pacific warming will be produced by climate change. The temporal frequency of these changes, however, are distinct. WPWM varies decadally, while ENSO is dominated by interannual variability. Future WPWM and ENSO warming may manifest as a tendency toward warm West Pacific SST, punctuated by extreme warm East Pacific events. WPWM EOFs from Global Precipitation Climatology Project (GPCP) precipitation also identify dramatic WPWM-related declines in the Greater Horn of Africa and NME/SWE.

Negative impacts of high temperatures on growth of black spruce forests intensify with the anticipated climate warming.

PubMed

Girardin, Martin P; Hogg, Edward H; Bernier, Pierre Y; Kurz, Werner A; Guo, Xiao Jing; Cyr, Guillaume

2016-02-01

An increasing number of studies conclude that water limitations and heat stress may hinder the capacity of black spruce (Picea mariana (Mill.) B.S.P.) trees, a dominant species of Canada's boreal forests, to grow and assimilate atmospheric carbon. However, there is currently no scientific consensus on the future of these forests over the next century in the context of widespread climate warming. The large spatial extent of black spruce forests across the Canadian boreal forest and associated variability in climate, demography, and site conditions pose challenges for projecting future climate change responses. Here we provide an evaluation of the impacts of climate warming and drying, as well as increasing [CO2 ], on the aboveground productivity of black spruce forests across Canada south of 60°N for the period 1971 to 2100. We use a new extensive network of tree-ring data obtained from Canada's National Forest Inventory, spatially explicit simulations of net primary productivity (NPP) and its drivers, and multivariate statistical modeling. We found that soil water availability is a significant driver of black spruce interannual variability in productivity across broad areas of the western to eastern Canadian boreal forest. Interannual variability in productivity was also found to be driven by autotrophic respiration in the warmest regions. In most regions, the impacts of soil water availability and respiration on interannual variability in productivity occurred during the phase of carbohydrate accumulation the year preceding tree-ring formation. Results from projections suggest an increase in the importance of soil water availability and respiration as limiting factors on NPP over the next century due to warming, but this response may vary to the extent that other factors such as carbon dioxide fertilization, and respiration acclimation to high temperature, contribute to dampening these limitations. © 2015 Her Majesty the Queen in Right of Canada. Reproduced with

Extreme weather events in Iran under a changing climate

NASA Astrophysics Data System (ADS)

Alizadeh-Choobari, Omid; Najafi, M. S.

2018-01-01

Observations unequivocally show that Iran has been rapidly warming over recent decades, which in sequence has triggered a wide range of climatic impacts. Meteorological records of several ground stations across Iran with daily temporal resolution for the period 1951-2013 were analyzed to investigate the climate change and its impact on some weather extremes. Iran has warmed by nearly 1.3 °C during the period 1951-2013 (+0.2 °C per decade), with an increase of the minimum temperature at a rate two times that of the maximum. Consequently, an increase in the frequency of heat extremes and a decrease in the frequency of cold extremes have been observed. The annual precipitation has decreased by 8 mm per decade, causing an expansion of Iran's dry zones. Previous studies have pointed out that warming is generally associated with more frequent heavy precipitation because a warmer air can hold more moisture. Nevertheless, warming in Iran has been associated with more frequent light precipitation, but less frequent moderate, heavy and extremely heavy precipitation. This is because in the subtropical dry zones, a longer time is required to recharge the atmosphere with water vapour in a warmer climate, causing more water vapour to be transported from the subtropics to high latitudes before precipitations forms. In addition, the altitude of the condensation level increases in a warmer climate in subtropical regions, causing an overall decrease of precipitation. We argue that changing in the frequency of heavy precipitation in response to warming varies depending on the geographical location. Warming over the dry subtropical regions is associated with a decrease in the frequency of heavy precipitation, while an increase is expected over both subpolar and tropical regions. The warmer climate has also led to the increase in the frequency of both thunderstorms (driven by convective heating) and dust events over Iran.

Climate impacts on human livelihoods at 1.5° and 2° of warming

NASA Astrophysics Data System (ADS)

Lissner, Tabea

2017-04-01

The measurement of impacts of climate change on socio-economic systems remains challenging and especially multi-dimensional outcome measures remain scarce. Climate impacts can directly affect many dimensions of human livelihoods, which cannot be addressed by monetary assessments alone. Multi-dimensional measures are essential in order to understand the full range of consequences of climate change and to understand the costs that higher levels of warming may have, not only in economic terms, but also in terms of non-market impacts on human livelihood. The AHEAD framework aims at measuring "Adequate Human livelihood conditions for wEll-being And Development" in a multi-dimensional framework, allowing to focus on resources and conditions which are a requirement to attain well-being. In this contribution we build on previous implementations of AHEAD and focus on differences in climate impacts at 1.5° and 2° of warming in order to improve our understanding of the societal consequences of these different warming levels.

Species traits and climate velocity explain geographic range shifts in an ocean-warming hotspot.

PubMed

Sunday, Jennifer M; Pecl, Gretta T; Frusher, Stewart; Hobday, Alistair J; Hill, Nicole; Holbrook, Neil J; Edgar, Graham J; Stuart-Smith, Rick; Barrett, Neville; Wernberg, Thomas; Watson, Reg A; Smale, Dan A; Fulton, Elizabeth A; Slawinski, Dirk; Feng, Ming; Radford, Ben T; Thompson, Peter A; Bates, Amanda E

2015-09-01

Species' ranges are shifting globally in response to climate warming, with substantial variability among taxa, even within regions. Relationships between range dynamics and intrinsic species traits may be particularly apparent in the ocean, where temperature more directly shapes species' distributions. Here, we test for a role of species traits and climate velocity in driving range extensions in the ocean-warming hotspot of southeast Australia. Climate velocity explained some variation in range shifts, however, including species traits more than doubled the variation explained. Swimming ability, omnivory and latitudinal range size all had positive relationships with range extension rate, supporting hypotheses that increased dispersal capacity and ecological generalism promote extensions. We find independent support for the hypothesis that species with narrow latitudinal ranges are limited by factors other than climate. Our findings suggest that small-ranging species are in double jeopardy, with limited ability to escape warming and greater intrinsic vulnerability to stochastic disturbances. © 2015 John Wiley & Sons Ltd/CNRS.

Winter Season Mortality: Will Climate Warming Bring Benefits?

PubMed

Kinney, Patrick L; Schwartz, Joel; Pascal, Mathilde; Petkova, Elisaveta; Tertre, Alain Le; Medina, Sylvia; Vautard, Robert

2015-06-01

Extreme heat events are associated with spikes in mortality, yet death rates are on average highest during the coldest months of the year. Under the assumption that most winter excess mortality is due to cold temperature, many previous studies have concluded that winter mortality will substantially decline in a warming climate. We analyzed whether and to what extent cold temperatures are associated with excess winter mortality across multiple cities and over multiple years within individual cities, using daily temperature and mortality data from 36 US cities (1985-2006) and 3 French cities (1971-2007). Comparing across cities, we found that excess winter mortality did not depend on seasonal temperature range, and was no lower in warmer vs. colder cities, suggesting that temperature is not a key driver of winter excess mortality. Using regression models within monthly strata, we found that variability in daily mortality within cities was not strongly influenced by winter temperature. Finally we found that inadequate control for seasonality in analyses of the effects of cold temperatures led to spuriously large assumed cold effects, and erroneous attribution of winter mortality to cold temperatures. Our findings suggest that reductions in cold-related mortality under warming climate may be much smaller than some have assumed. This should be of interest to researchers and policy makers concerned with projecting future health effects of climate change and developing relevant adaptation strategies.

Winter season mortality: will climate warming bring benefits?

NASA Astrophysics Data System (ADS)

Kinney, Patrick L.; Schwartz, Joel; Pascal, Mathilde; Petkova, Elisaveta; Le Tertre, Alain; Medina, Sylvia; Vautard, Robert

2015-06-01

Extreme heat events are associated with spikes in mortality, yet death rates are on average highest during the coldest months of the year. Under the assumption that most winter excess mortality is due to cold temperature, many previous studies have concluded that winter mortality will substantially decline in a warming climate. We analyzed whether and to what extent cold temperatures are associated with excess winter mortality across multiple cities and over multiple years within individual cities, using daily temperature and mortality data from 36 US cities (1985-2006) and 3 French cities (1971-2007). Comparing across cities, we found that excess winter mortality did not depend on seasonal temperature range, and was no lower in warmer vs. colder cities, suggesting that temperature is not a key driver of winter excess mortality. Using regression models within monthly strata, we found that variability in daily mortality within cities was not strongly influenced by winter temperature. Finally we found that inadequate control for seasonality in analyses of the effects of cold temperatures led to spuriously large assumed cold effects, and erroneous attribution of winter mortality to cold temperatures. Our findings suggest that reductions in cold-related mortality under warming climate may be much smaller than some have assumed. This should be of interest to researchers and policy makers concerned with projecting future health effects of climate change and developing relevant adaptation strategies.

Links between plant species’ spatial and temporal responses to a warming climate

PubMed Central

Amano, Tatsuya; Freckleton, Robert P.; Queenborough, Simon A.; Doxford, Simon W.; Smithers, Richard J.; Sparks, Tim H.; Sutherland, William J.

2014-01-01

To generate realistic projections of species’ responses to climate change, we need to understand the factors that limit their ability to respond. Although climatic niche conservatism, the maintenance of a species’s climatic niche over time, is a critical assumption in niche-based species distribution models, little is known about how universal it is and how it operates. In particular, few studies have tested the role of climatic niche conservatism via phenological changes in explaining the reported wide variance in the extent of range shifts among species. Using historical records of the phenology and spatial distribution of British plants under a warming climate, we revealed that: (i) perennial species, as well as those with weaker or lagged phenological responses to temperature, experienced a greater increase in temperature during flowering (i.e. failed to maintain climatic niche via phenological changes); (ii) species that failed to maintain climatic niche via phenological changes showed greater northward range shifts; and (iii) there was a complementary relationship between the levels of climatic niche conservatism via phenological changes and range shifts. These results indicate that even species with high climatic niche conservatism might not show range shifts as instead they track warming temperatures during flowering by advancing their phenology. PMID:24478304

Assessing Climate Change Impacts for Military Installations in the Southwest United States During the Warm Season

NASA Astrophysics Data System (ADS)

Castro, C.

2013-05-01

Arid and semi-arid regions are experiencing some of the most adverse impacts of climate change with increased heat waves, droughts, and extreme weather. These events will likely exacerbate socioeconomic and political instabilities in regions where the United States has vital strategic interests and ongoing military operations. The Southwest U.S. is strategically important in that it houses some of the most spatially expansive and important military installations in the country. The majority of severe weather events in the Southwest occur in association with the North American monsoon system (NAMS), and current observational record has shown a 'wet gets wetter and dry gets drier' global monsoon precipitation trend. We seek to evaluate the warm season extreme weather projection in the Southwest U.S., and how the extremes can affect Department of Defense (DoD) military facilities in that region. A baseline methodology is being developed to select extreme warm season weather events based on historical sounding data and moisture surge observations from Gulf of California. Numerical Weather Prediction (NWP)-type high resolution simulations will be performed for the extreme events identified from Weather Research and Forecast (WRF) model simulations initiated from IPCC GCM and NCAR Reanalysis data in both climate control and climate change periods. The magnitude in extreme event changes will be analyzed, and the synoptic forcing patterns of the future severe thunderstorms will provide a guide line to assess if the military installations in the Southwest will become more or less susceptible to severe weather in the future.

The Effect of Urban Heat Island on Climate Warming in the Yangtze River Delta Urban Agglomeration in China.

PubMed

Huang, Qunfang; Lu, Yuqi

2015-07-27

The Yangtze River Delta (YRD) has experienced rapid urbanization and dramatic economic development since 1978 and the Yangtze River Delta urban agglomeration (YRDUA) has been one of the three largest urban agglomerations in China. We present evidence of a significant urban heat island (UHI) effect on climate warming based on an analysis of the impacts of the urbanization rate, urban population, and land use changes on the warming rate of the daily average, minimal (nighttime) and maximal (daytime) air temperature in the YRDUA using 41 meteorological stations observation data. The effect of the UHI on climate warming shows a large spatial variability. The average warming rates of average air temperature of huge cities, megalopolises, large cities, medium-sized cities, and small cities are 0.483, 0.314 ± 0.030, 0.282 ± 0.042, 0.225 ± 0.044 and 0.179 ± 0.046 °C/decade during the period of 1957-2013, respectively. The average warming rates of huge cities and megalopolises are significantly higher than those of medium-sized cities and small cities, indicating that the UHI has a significant effect on climate warming (t-test, p < 0.05). Significantly positive correlations are found between the urbanization rate, population, built-up area and warming rate of average air temperature (p < 0.001). The average warming rate of average air temperature attributable to urbanization is 0.124 ± 0.074 °C/decade in the YRDUA. Urbanization has a measurable effect on the observed climate warming in the YRD aggravating the global climate warming.

The Effect of Urban Heat Island on Climate Warming in the Yangtze River Delta Urban Agglomeration in China

PubMed Central

Huang, Qunfang; Lu, Yuqi

2015-01-01

The Yangtze River Delta (YRD) has experienced rapid urbanization and dramatic economic development since 1978 and the Yangtze River Delta urban agglomeration (YRDUA) has been one of the three largest urban agglomerations in China. We present evidence of a significant urban heat island (UHI) effect on climate warming based on an analysis of the impacts of the urbanization rate, urban population, and land use changes on the warming rate of the daily average, minimal (nighttime) and maximal (daytime) air temperature in the YRDUA using 41 meteorological stations observation data. The effect of the UHI on climate warming shows a large spatial variability. The average warming rates of average air temperature of huge cities, megalopolises, large cities, medium-sized cities, and small cities are 0.483, 0.314 ± 0.030, 0.282 ± 0.042, 0.225 ± 0.044 and 0.179 ± 0.046 °C/decade during the period of 1957–2013, respectively. The average warming rates of huge cities and megalopolises are significantly higher than those of medium-sized cities and small cities, indicating that the UHI has a significant effect on climate warming (t-test, p < 0.05). Significantly positive correlations are found between the urbanization rate, population, built-up area and warming rate of average air temperature (p < 0.001). The average warming rate of average air temperature attributable to urbanization is 0.124 ± 0.074 °C/decade in the YRDUA. Urbanization has a measurable effect on the observed climate warming in the YRD aggravating the global climate warming. PMID:26225986

The impact of global warming on the range distribution of different climatic groups of Aspidoscelis costata costata.

PubMed

Güizado-Rodríguez, Martha Anahí; Ballesteros-Barrera, Claudia; Casas-Andreu, Gustavo; Barradas-Miranda, Victor Luis; Téllez-Valdés, Oswaldo; Salgado-Ugarte, Isaías Hazarmabeth

2012-12-01

The ectothermic nature of reptiles makes them especially sensitive to global warming. Although climate change and its implications are a frequent topic of detailed studies, most of these studies are carried out without making a distinction between populations. Here we present the first study of an Aspidoscelis species that evaluates the effects of global warming on its distribution using ecological niche modeling. The aims of our study were (1) to understand whether predicted warmer climatic conditions affect the geographic potential distribution of different climatic groups of Aspidoscelis costata costata and (2) to identify potential altitudinal changes of these groups under global warming. We used the maximum entropy species distribution model (MaxEnt) to project the potential distributions expected for the years 2020, 2050, and 2080 under a single simulated climatic scenario. Our analysis suggests that some climatic groups of Aspidoscelis costata costata will exhibit reductions and in others expansions in their distribution, with potential upward shifts toward higher elevation in response to climate warming. Different climatic groups were revealed in our analysis that subsequently showed heterogeneous responses to climatic change illustrating the complex nature of species geographic responses to environmental change and the importance of modeling climatic or geographic groups and/or populations instead of the entire species' range treated as a homogeneous entity.

Global warming precipitation accumulation increases above the current-climate cutoff scale

PubMed Central

Sahany, Sandeep; Stechmann, Samuel N.; Bernstein, Diana N.

2017-01-01

Precipitation accumulations, integrated over rainfall events, can be affected by both intensity and duration of the storm event. Thus, although precipitation intensity is widely projected to increase under global warming, a clear framework for predicting accumulation changes has been lacking, despite the importance of accumulations for societal impacts. Theory for changes in the probability density function (pdf) of precipitation accumulations is presented with an evaluation of these changes in global climate model simulations. We show that a simple set of conditions implies roughly exponential increases in the frequency of the very largest accumulations above a physical cutoff scale, increasing with event size. The pdf exhibits an approximately power-law range where probability density drops slowly with each order of magnitude size increase, up to a cutoff at large accumulations that limits the largest events experienced in current climate. The theory predicts that the cutoff scale, controlled by the interplay of moisture convergence variance and precipitation loss, tends to increase under global warming. Thus, precisely the large accumulations above the cutoff that are currently rare will exhibit increases in the warmer climate as this cutoff is extended. This indeed occurs in the full climate model, with a 3 °C end-of-century global-average warming yielding regional increases of hundreds of percent to >1,000% in the probability density of the largest accumulations that have historical precedents. The probabilities of unprecedented accumulations are also consistent with the extension of the cutoff. PMID:28115693

Global warming precipitation accumulation increases above the current-climate cutoff scale

NASA Astrophysics Data System (ADS)

Neelin, J. David; Sahany, Sandeep; Stechmann, Samuel N.; Bernstein, Diana N.

2017-02-01

Precipitation accumulations, integrated over rainfall events, can be affected by both intensity and duration of the storm event. Thus, although precipitation intensity is widely projected to increase under global warming, a clear framework for predicting accumulation changes has been lacking, despite the importance of accumulations for societal impacts. Theory for changes in the probability density function (pdf) of precipitation accumulations is presented with an evaluation of these changes in global climate model simulations. We show that a simple set of conditions implies roughly exponential increases in the frequency of the very largest accumulations above a physical cutoff scale, increasing with event size. The pdf exhibits an approximately power-law range where probability density drops slowly with each order of magnitude size increase, up to a cutoff at large accumulations that limits the largest events experienced in current climate. The theory predicts that the cutoff scale, controlled by the interplay of moisture convergence variance and precipitation loss, tends to increase under global warming. Thus, precisely the large accumulations above the cutoff that are currently rare will exhibit increases in the warmer climate as this cutoff is extended. This indeed occurs in the full climate model, with a 3 °C end-of-century global-average warming yielding regional increases of hundreds of percent to >1,000% in the probability density of the largest accumulations that have historical precedents. The probabilities of unprecedented accumulations are also consistent with the extension of the cutoff.

Global warming precipitation accumulation increases above the current-climate cutoff scale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neelin, J. David; Sahany, Sandeep; Stechmann, Samuel N.

Precipitation accumulations, integrated over rainfall events, can be affected by both intensity and duration of the storm event. Thus, although precipitation intensity is widely projected to increase under global warming, a clear framework for predicting accumulation changes has been lacking, despite the importance of accumulations for societal impacts. Theory for changes in the probability density function (pdf) of precipitation accumulations is presented with an evaluation of these changes in global climate model simulations. We show that a simple set of conditions implies roughly exponential increases in the frequency of the very largest accumulations above a physical cutoff scale, increasing withmore » event size. The pdf exhibits an approximately power-law range where probability density drops slowly with each order of magnitude size increase, up to a cutoff at large accumulations that limits the largest events experienced in current climate. The theory predicts that the cutoff scale, controlled by the interplay of moisture convergence variance and precipitation loss, tends to increase under global warming. Thus, precisely the large accumulations above the cutoff that are currently rare will exhibit increases in the warmer climate as this cutoff is extended. This indeed occurs in the full climate model, with a 3 °C end-of-century global-average warming yielding regional increases of hundreds of percent to >1,000% in the probability density of the largest accumulations that have historical precedents. The probabilities of unprecedented accumulations are also consistent with the extension of the cutoff.« less

Global warming precipitation accumulation increases above the current-climate cutoff scale.

PubMed

Neelin, J David; Sahany, Sandeep; Stechmann, Samuel N; Bernstein, Diana N

2017-02-07

Precipitation accumulations, integrated over rainfall events, can be affected by both intensity and duration of the storm event. Thus, although precipitation intensity is widely projected to increase under global warming, a clear framework for predicting accumulation changes has been lacking, despite the importance of accumulations for societal impacts. Theory for changes in the probability density function (pdf) of precipitation accumulations is presented with an evaluation of these changes in global climate model simulations. We show that a simple set of conditions implies roughly exponential increases in the frequency of the very largest accumulations above a physical cutoff scale, increasing with event size. The pdf exhibits an approximately power-law range where probability density drops slowly with each order of magnitude size increase, up to a cutoff at large accumulations that limits the largest events experienced in current climate. The theory predicts that the cutoff scale, controlled by the interplay of moisture convergence variance and precipitation loss, tends to increase under global warming. Thus, precisely the large accumulations above the cutoff that are currently rare will exhibit increases in the warmer climate as this cutoff is extended. This indeed occurs in the full climate model, with a 3 °C end-of-century global-average warming yielding regional increases of hundreds of percent to >1,000% in the probability density of the largest accumulations that have historical precedents. The probabilities of unprecedented accumulations are also consistent with the extension of the cutoff.

Global warming precipitation accumulation increases above the current-climate cutoff scale

DOE PAGES

Neelin, J. David; Sahany, Sandeep; Stechmann, Samuel N.; ...

2017-01-23

Precipitation accumulations, integrated over rainfall events, can be affected by both intensity and duration of the storm event. Thus, although precipitation intensity is widely projected to increase under global warming, a clear framework for predicting accumulation changes has been lacking, despite the importance of accumulations for societal impacts. Theory for changes in the probability density function (pdf) of precipitation accumulations is presented with an evaluation of these changes in global climate model simulations. We show that a simple set of conditions implies roughly exponential increases in the frequency of the very largest accumulations above a physical cutoff scale, increasing withmore » event size. The pdf exhibits an approximately power-law range where probability density drops slowly with each order of magnitude size increase, up to a cutoff at large accumulations that limits the largest events experienced in current climate. The theory predicts that the cutoff scale, controlled by the interplay of moisture convergence variance and precipitation loss, tends to increase under global warming. Thus, precisely the large accumulations above the cutoff that are currently rare will exhibit increases in the warmer climate as this cutoff is extended. This indeed occurs in the full climate model, with a 3 °C end-of-century global-average warming yielding regional increases of hundreds of percent to >1,000% in the probability density of the largest accumulations that have historical precedents. The probabilities of unprecedented accumulations are also consistent with the extension of the cutoff.« less

Climate warming affects biological invasions by shifting interactions of plants and herbivores.

PubMed

Lu, Xinmin; Siemann, Evan; Shao, Xu; Wei, Hui; Ding, Jianqing

2013-08-01

Plants and herbivorous insects can each be dramatically affected by temperature. Climate warming may impact plant invasion success directly but also indirectly through changes in their natural enemies. To date, however, there are no tests of how climate warming shifts the interactions among invasive plants and their natural enemies to affect invasion success. Field surveys covering the full latitudinal range of invasive Alternanthera philoxeroides in China showed that a beetle introduced for biocontrol was rare or absent at higher latitudes. In contrast, plant cover and mass increased with latitude. In a 2-year field experiment near the northern limit of beetle distribution, we found the beetle sustained populations across years under elevated temperature, dramatically decreasing A. philoxeroides growth, but it failed to overwinter in ambient temperature. Together, these results suggest that warming will allow the natural enemy to expand its range, potentially benefiting biocontrol in regions that are currently too cold for the natural enemy. However, the invader may also expand its range further north in response to warming. In such cases where plants tolerate cold better than their natural enemies, the geographical gap between plant and herbivorous insect ranges may not disappear but will shift to higher latitudes, leading to a new zone of enemy release. Therefore, warming will not only affect plant invasions directly but also drive either enemy release or increase that will result in contrasting effects on invasive plants. The findings are also critical for future management of invasive species under climate change. © 2013 John Wiley & Sons Ltd.

Extreme warming challenges sentinel status of kelp forests as indicators of climate change.

PubMed

Reed, Daniel; Washburn, Libe; Rassweiler, Andrew; Miller, Robert; Bell, Tom; Harrer, Shannon

2016-12-13

The desire to use sentinel species as early warning indicators of impending climate change effects on entire ecosystems is attractive, but we need to verify that such approaches have sound biological foundations. A recent large-scale warming event in the North Pacific Ocean of unprecedented magnitude and duration allowed us to evaluate the sentinel status of giant kelp, a coastal foundation species that thrives in cold, nutrient-rich waters and is considered sensitive to warming. Here, we show that giant kelp and the majority of species that associate with it did not presage ecosystem effects of extreme warming off southern California despite giant kelp's expected vulnerability. Our results challenge the general perception that kelp-dominated systems are highly vulnerable to extreme warming events and expose the more general risk of relying on supposed sentinel species that are assumed to be very sensitive to climate change.

Are treelines advancing? A global meta-analysis of treeline response to climate warming.

PubMed

Harsch, Melanie A; Hulme, Philip E; McGlone, Matt S; Duncan, Richard P

2009-10-01

Treelines are temperature sensitive transition zones that are expected to respond to climate warming by advancing beyond their current position. Response to climate warming over the last century, however, has been mixed, with some treelines showing evidence of recruitment at higher altitudes and/or latitudes (advance) whereas others reveal no marked change in the upper limit of tree establishment. To explore this variation, we analysed a global dataset of 166 sites for which treeline dynamics had been recorded since 1900 AD. Advance was recorded at 52% of sites with only 1% reporting treeline recession. Treelines that experienced strong winter warming were more likely to have advanced, and treelines with a diffuse form were more likely to have advanced than those with an abrupt or krummholz form. Diffuse treelines may be more responsive to warming because they are more strongly growth limited, whereas other treeline forms may be subject to additional constraints.

Extreme warming challenges sentinel status of kelp forests as indicators of climate change

NASA Astrophysics Data System (ADS)

Reed, Daniel; Washburn, Libe; Rassweiler, Andrew; Miller, Robert; Bell, Tom; Harrer, Shannon

2016-12-01

The desire to use sentinel species as early warning indicators of impending climate change effects on entire ecosystems is attractive, but we need to verify that such approaches have sound biological foundations. A recent large-scale warming event in the North Pacific Ocean of unprecedented magnitude and duration allowed us to evaluate the sentinel status of giant kelp, a coastal foundation species that thrives in cold, nutrient-rich waters and is considered sensitive to warming. Here, we show that giant kelp and the majority of species that associate with it did not presage ecosystem effects of extreme warming off southern California despite giant kelp's expected vulnerability. Our results challenge the general perception that kelp-dominated systems are highly vulnerable to extreme warming events and expose the more general risk of relying on supposed sentinel species that are assumed to be very sensitive to climate change.

Inconsistent Range Shifts within Species Highlight Idiosyncratic Responses to Climate Warming

PubMed Central

Gibson-Reinemer, Daniel K.; Rahel, Frank J.

2015-01-01

Climate in part determines species’ distributions, and species’ distributions are shifting in response to climate change. Strong correlations between the magnitude of temperature changes and the extent of range shifts point to warming temperatures as the single most influential factor causing shifts in species’ distributions species. However, other abiotic and biotic factors may alter or even reverse these patterns. The importance of temperature relative to these other factors can be evaluated by examining range shifts of the same species in different geographic areas. When the same species experience warming in different geographic areas, the extent to which they show range shifts that are similar in direction and magnitude is a measure of temperature’s importance. We analyzed published studies to identify species that have documented range shifts in separate areas. For 273 species of plants, birds, mammals, and marine invertebrates with range shifts measured in multiple geographic areas, 42-50% show inconsistency in the direction of their range shifts, despite experiencing similar warming trends. Inconsistency of within-species range shifts highlights how biotic interactions and local, non-thermal abiotic conditions may often supersede the direct physiological effects of temperature. Assemblages show consistent responses to climate change, but this predictability does not appear to extend to species considered individually. PMID:26162013

Impacts of global warming of 1.5 °C and 2.0 °C on precipitation patterns in China by regional climate model (COSMO-CLM)

NASA Astrophysics Data System (ADS)

Sun, Hemin; Wang, Anqian; Zhai, Jianqing; Huang, Jinlong; Wang, Yanjun; Wen, Shanshan; Zeng, Xiaofan; Su, Buda

2018-05-01

Regional precipitation patterns may change in a warmer climate, thereby increasing flood and drought risks. In this paper, annual, annual maximum, intense, heavy, moderate, light, and trace precipitation are employed as indicators to assess changes in precipitation patterns under two scenarios in which the global mean temperature increases by 1.5 °C and 2.0 °C relative to pre-industrial levels using the regional climate model COSMO-CLM (CCLM). The results show that annual precipitation in China will be approximately 2.5% higher under 1.5 °C warming relative to the present-day baseline (1980-2009), although it will decrease by approximately 4.0% under an additional 0.5 °C increase in global mean temperature. This trend is spatially consistent for regions with annual precipitation of 400-800 mm, which has experienced a drying trend during the past half century; thus, limiting global warming to 1.5 °C may mitigate these drying conditions. The annual maximum precipitation continues to increase from present day levels to the 2.0 °C warming scenario. Relative to the baseline period, the frequency of trace and light precipitation days exhibits a negative trend, while that of moderate, heavy, and intense precipitation days has a positive trend under the 1.5 °C warming scenario. For the 2.0 °C warming world, the frequency of days is projected to decrease for all precipitation categories, although the intensity of intense precipitation increases. Spatially, a decrease in the number of precipitation days is expected to continue in central and northern China, where a drying trend has persisted over the past half century. Southeastern China, which already suffers greatly from flooding, is expected to face more heavy and intense precipitation with an additional 0.5 °C increase in global mean temperature. Meanwhile, the intensity of intense precipitation is expected to increase in northern China, and the contribution of light and moderate precipitation to the annual

West African warming: Investigating Temperature Trends and their relation between Precipitation Trends over West African Sahel.

NASA Astrophysics Data System (ADS)

LY, M., Jr.

2014-12-01

It is now admitted that the West African region faces a lot of constraints due to the comprehensiveness of the high climate variability and potential climate change. This is mainly due to the lack of a large number of datasets and long-term records as summarized in the in the IPCC reports. This paper aims to provide improved knowledge and evidence on current and future climate conditions, for better manage climate variability over seasons and from year to year and strengthen the capacity to adapt to future climate change. In this regards, we analyse the evolution of some extreme temperature and precipitation indices over a large area of West Africa. Prior results show a general warming trend at individual stations throughout the region during the period from 1960 to 2010, namely negative trends in the number of cool nights, and positive trends in the number of warm days and length of warm spells. Trends in rainfall-related indices are not as uniform as the ones in temperatures, rather they display marked multi-decadal variability, as expected. To refine analyses of temperature variations and their relation to precipitation we investigated on cluster analysis aimed at distinguishing different sub-regions, such as continental and coastal, and relevant seasons, such as wet, dry/cold and dry warm. This will contribute to significantly lower uncertainties by developing better and more tailored temperature and precipitation trends to inform the user communities on climate related risks, as well as enhance their resilience to food insecurity and other climate related disasters.

Trophic level responses differ as climate warms in Ireland

NASA Astrophysics Data System (ADS)

Donnelly, Alison; Yu, Rong; Liu, Lingling

2015-08-01

Effective ecosystem functioning relies on successful species interaction. However, this delicate balance may be disrupted if species do not respond to environmental change at a similar rate. Here we examine trends in the timing of spring phenophases of groups of species occupying three trophic levels as a potential indicator of ecosystem response to climate warming in Ireland. The data sets were of varying length (1976-2009) and from varying locations: (1) timing of leaf unfolding and May Shoot of a range of broadleaf and conifer tree species, (2) first appearance dates of a range of moth species, and (3) first arrival dates of a range of spring migrant birds. All three groups revealed a statistically significant ( P<0.01 and P<0.001) advance in spring phenology that was driven by rising spring temperature ( P<0.05; 0.45 °C /decade). However, the rate of advance was greater for moths (1.8 days/year), followed by birds (0.37 days/year) and trees (0.29 days/year). In addition, the length of time between (1) moth emergence and leaf unfolding and (2) moth emergence and bird arrival decreased significantly ( P<0.05 and P<0.001, respectively), indicating a decrease in the timing between food supply and demand. These differing trophic level response rates demonstrate the potential for a mismatch in the timing of interdependent phenophases as temperatures rise. Even though these data were not specifically collected to examine climate warming impacts, we conclude that such data may be used as an early warning indicator and as a means to monitor the potential for future ecosystem disruption to occur as climate warms.

Trophic level responses differ as climate warms in Ireland.

PubMed

Donnelly, Alison; Yu, Rong; Liu, Lingling

2015-08-01

Effective ecosystem functioning relies on successful species interaction. However, this delicate balance may be disrupted if species do not respond to environmental change at a similar rate. Here we examine trends in the timing of spring phenophases of groups of species occupying three trophic levels as a potential indicator of ecosystem response to climate warming in Ireland. The data sets were of varying length (1976-2009) and from varying locations: (1) timing of leaf unfolding and May Shoot of a range of broadleaf and conifer tree species, (2) first appearance dates of a range of moth species, and (3) first arrival dates of a range of spring migrant birds. All three groups revealed a statistically significant (P<0.01 and P<0.001) advance in spring phenology that was driven by rising spring temperature (P<0.05; 0.45 °C /decade). However, the rate of advance was greater for moths (1.8 days/year), followed by birds (0.37 days/year) and trees (0.29 days/year). In addition, the length of time between (1) moth emergence and leaf unfolding and (2) moth emergence and bird arrival decreased significantly (P<0.05 and P<0.001, respectively), indicating a decrease in the timing between food supply and demand. These differing trophic level response rates demonstrate the potential for a mismatch in the timing of interdependent phenophases as temperatures rise. Even though these data were not specifically collected to examine climate warming impacts, we conclude that such data may be used as an early warning indicator and as a means to monitor the potential for future ecosystem disruption to occur as climate warms.

Climate driven egg and hatchling mortality threatens survival of eastern Pacific leatherback turtles.

PubMed

Santidrián Tomillo, Pilar; Saba, Vincent S; Blanco, Gabriela S; Stock, Charles A; Paladino, Frank V; Spotila, James R

2012-01-01

Egg-burying reptiles need relatively stable temperature and humidity in the substrate surrounding their eggs for successful development and hatchling emergence. Here we show that egg and hatchling mortality of leatherback turtles (Dermochelys coriacea) in northwest Costa Rica were affected by climatic variability (precipitation and air temperature) driven by the El Niño Southern Oscillation (ENSO). Drier and warmer conditions associated with El Niño increased egg and hatchling mortality. The fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC) projects a warming and drying in Central America and other regions of the World, under the SRES A2 development scenario. Using projections from an ensemble of global climate models contributed to the IPCC report, we project that egg and hatchling survival will rapidly decline in the region over the next 100 years by ∼50-60%, due to warming and drying in northwestern Costa Rica, threatening the survival of leatherback turtles. Warming and drying trends may also threaten the survival of sea turtles in other areas affected by similar climate changes.

Simulated climate warming alters phenological synchrony between an outbreak insect herbivore and host trees.

PubMed

Schwartzberg, Ezra G; Jamieson, Mary A; Raffa, Kenneth F; Reich, Peter B; Montgomery, Rebecca A; Lindroth, Richard L

2014-07-01

As the world's climate warms, the phenologies of interacting organisms in seasonally cold environments may advance at differing rates, leading to alterations in phenological synchrony that can have important ecological consequences. For temperate and boreal species, the timing of early spring development plays a key role in plant-herbivore interactions and can influence insect performance, outbreak dynamics, and plant damage. We used a field-based, meso-scale free-air forest warming experiment (B4WarmED) to examine the effects of elevated temperature on the phenology and performance of forest tent caterpillar (Malacosoma disstria) in relation to the phenology of two host trees, aspen (Populus tremuloides) and birch (Betula papyrifera). Results of our 2-year study demonstrated that spring phenology advanced for both insects and trees, with experimentally manipulated increases in temperature of 1.7 and 3.4 °C. However, tree phenology advanced more than insect phenology, resulting in altered phenological synchrony. Specifically, we observed a decrease in the time interval between herbivore egg hatch and budbreak of aspen in both years and birch in one year. Moreover, warming decreased larval development time from egg hatch to pupation, but did not affect pupal mass. Larvae developed more quickly on aspen than birch, but pupal mass was not affected by host species. Our study reveals that warming-induced phenological shifts can alter the timing of ecological interactions across trophic levels. These findings illustrate one mechanism by which climate warming could mediate insect herbivore outbreaks, and also highlights the importance of climate change effects on trophic interactions.

Holocene climate in the western Great Lakes national parks and lakeshores: Implications for future climate change

USGS Publications Warehouse

Davis, Margaret; Douglas, Christine; Cole, K.L.; Winkler, Marge; Flaknes, Robyn

2000-01-01

We reconstruct Holocene climate history (last 10,000 years) for each of the U.S. National Park Service units in the western Great Lakes region in order to evaluate their sensitivity to global warming. Annual precipitation, annual temperature, and July and January temperatures were reconstructed by comparing fossil pollen in lake sediment with pollen in surface samples, assuming that ancient climates were similar to modern climate near analogous surface samples. In the early Holocene, most of the parks experienced colder winters, warmer summers, and lower precipitation than today. An exception is Voyageurs National Park in northern Minnesota where, by 8000 years ago, January temperatures were higher than today. The combination of high mean annual temperature and lower precipitation at Voyageurs resulted in a dry period between 8000 and 5000 years ago, similar to the Prairie Period in regions to the south and west. A mid-Holocene warm-dry period also occurred at other northern and central parks but was much less strongly developed. In southern parks there was no clear evidence of a mid-Holocene warm-dry period. These differences suggest that global model predictions of a warm, dry climate in the northern Great Plains under doubled atmospheric CO2 may be more applicable to Voyageurs than to the other parks. The contrast in reconstructed temperatures at Voyageurs and Isle Royale indicates that the ameliorating effect of the Great Lakes on temperatures has been in effect throughout the Holocene and presumably will continue in the future, thus reducing the potential for species loss caused by future temperature extremes. Increased numbers of mesic trees at all of the parks in the late Holocene reflect increasing annual precipitation. This trend toward more mesic conditions began 6000 years ago in the south and 4000 years ago in the north and increased sharply in recent millennia at parks located today in lake-effect snow belts. This suggests that lake-effect snowfall is

Terra Data Confirm Warm, Dry U.S. Winter

NASA Technical Reports Server (NTRS)

2002-01-01

New maps of land surface temperature and snow cover produced by NASA's Terra satellite show this year's winter was warmer than last year's, and the snow line stayed farther north than normal. The observations confirm earlier National Oceanic and Atmospheric Administration reports that the United States was unusually warm and dry this past winter. (Click to read the NASA press release and to access higher-resolution images.) For the last two years, a new sensor aboard Terra has been collecting the most detailed global measurements ever made of our world's land surface temperatures and snow cover. The Moderate-resolution Imaging Spectroradiometer (MODIS) is already giving scientists new insights into our changing planet. Average temperatures during December 2001 through February 2002 for the contiguous United States appear to have been unseasonably warm from the Rockies eastward. In the top image the coldest temperatures appear black, while dark green, blue, red, yellow, and white indicate progressively warmer temperatures. MODIS observes both land surface temperature and emissivity, which indicates how efficiently a surface absorbs and emits thermal radiation. Compared to the winter of 2000-01, temperatures throughout much of the U.S. were warmer in 2001-02. The bottom image depicts the differences on a scale from dark blue (colder this year than last) to red (warmer this year than last). A large region of warm temperatures dominated the northern Great Plains, while the area around the Great Salt Lake was a cold spot. Images courtesy Robert Simmon, NASA GSFC, based upon data courtesy Zhengming Wan, MODIS Land Science Team member at the University of California, Santa Barbara's Institute for Computational Earth System Science

Is the Climate of Bering Sea Warming and Affecting the Ecosystem?

NASA Astrophysics Data System (ADS)

Overland, James E.; Stabeno, Phyllis J.

2004-08-01

Observations from the Bering Sea are good indicators of decadal shifts in climate, as the Bering is a transition region between the cold, dry Arctic air mass to the north, and the moist, relatively warm maritime air mass to the south. The Bering Sea is also a transition region between Arctic and sub-Arctic ecosystems; this boundary can be loosely identified with the extent of winter sea-ice cover. Like a similar transition zone in the eastern North Atlantic, the Bering Sea is experiencing a northward biogeographical shift in response to changing temperature and atmospheric forcing. If this shift continues over the next decade, it will have major impacts on commercial and subsistence harvests as Arctic species are displaced by sub-Arctic species. The stakes are enormous, as this rich and diverse ecosystem currently provides 47% of the U.S. fishery production by weight, and is home to 80% of the U.S. sea bird population, 95% of northern fur seals, and major populations of Steller sea lions, walrus, and whales.

Modelling middle pliocene warm climates of the USA

USGS Publications Warehouse

Haywood, A.M.; Valdes, P.J.; Sellwood, B.W.; Kaplan, J.O.; Dowsett, H.J.

2001-01-01

The middle Pliocene warm period represents a unique time slice in which to model and understand climatic processes operating under a warm climatic regime. Palaeoclimatic model simulations, focussed on the United States of America (USA), for the middle Pliocene (ca 3 Ma) were generated using the USGS PRISM2 2?? ?? 2?? data set of boundary conditions and the UK Meteorological Office's HadAMS General Circulation Model (GCM). Model results suggest that conditions in the USA during the middle Pliocene can be characterised as annually warmer (by 2?? to 4??C), less seasonal, wetter (by a maximum of 4 to 8 mm/day) and with an absence of freezing winters over the central and southern Great Plains. A sensitivity experiment suggests that the main forcing mechanisms for surface temperature changes in near coastal areas are the imposed Pliocene sea surface temperatures (SST's). In interior regions, reduced Northern Hemisphere terrestrial ice, combined with less snow cover and a reduction in the elevation of the western cordillera of North America, generate atmospheric circulation changes and positive albedo feedbacks that raise surface temperatures. A complex set of climatic feedback mechanisms cause an enhancement of the hydrological cycle magnifying the moisture bearing westerly wind belt during the winter season (Dec., Jan., Feb.). Predictions produced by the model are in broad agreement with available geological evidence. However, the GCM appears to underestimate precipitation levels in the interior and central regions of the southern USA. Copyright: Palaeontological Association, 22 June 2001.

Higher climatological temperature sensitivity of soil carbon in cold than warm climates

NASA Astrophysics Data System (ADS)

Koven, Charles D.; Hugelius, Gustaf; Lawrence, David M.; Wieder, William R.

2017-11-01

The projected loss of soil carbon to the atmosphere resulting from climate change is a potentially large but highly uncertain feedback to warming. The magnitude of this feedback is poorly constrained by observations and theory, and is disparately represented in Earth system models (ESMs). To assess the climatological temperature sensitivity of soil carbon, we calculate apparent soil carbon turnover times that reflect long-term and broad-scale rates of decomposition. Here, we show that the climatological temperature control on carbon turnover in the top metre of global soils is more sensitive in cold climates than in warm climates and argue that it is critical to capture this emergent ecosystem property in global-scale models. We present a simplified model that explains the observed high cold-climate sensitivity using only the physical scaling of soil freeze-thaw state across climate gradients. Current ESMs fail to capture this pattern, except in an ESM that explicitly resolves vertical gradients in soil climate and carbon turnover. An observed weak tropical temperature sensitivity emerges in a different model that explicitly resolves mineralogical control on decomposition. These results support projections of strong carbon-climate feedbacks from northern soils and demonstrate a method for ESMs to capture this emergent behaviour.

Evaluating the accuracy of climate change pattern emulation for low warming targets

NASA Astrophysics Data System (ADS)

Tebaldi, Claudia; Knutti, Reto

2018-05-01

Global climate policy is increasingly debating the value of very low warming targets, yet not many experiments conducted with global climate models in their fully coupled versions are currently available to help inform studies of the corresponding impacts. This raises the question whether a map of warming or precipitation change in a world 1.5 °C warmer than preindustrial can be emulated from existing simulations that reach higher warming targets, or whether entirely new simulations are required. Here we show that also for this type of low warming in strong mitigation scenarios, climate change signals are quite linear as a function of global temperature. Therefore, emulation techniques amounting to linear rescaling on the basis of global temperature change ratios (like simple pattern scaling) provide a viable way forward. The errors introduced are small relative to the spread in the forced response to a given scenario that we can assess from a multi-model ensemble. They are also small relative to the noise introduced into the estimates of the forced response by internal variability within a single model, which we can assess from either control simulations or initial condition ensembles. Challenges arise when scaling inadvertently reduces the inter-model spread or suppresses the internal variability, both important sources of uncertainty for impact assessment, or when the scenarios have very different characteristics in the composition of the forcings. Taking advantage of an available suite of coupled model simulations under low-warming and intermediate scenarios, we evaluate the accuracy of these emulation techniques and show that they are unlikely to represent a substantial contribution to the total uncertainty.

Innovative empirical approaches for inferring climate-warming impacts on plants in remote areas.

PubMed

De Frenne, Pieter

2015-02-01

The prediction of the effects of climate warming on plant communities across the globe has become a major focus of ecology, evolution and biodiversity conservation. However, many of the frequently used empirical approaches for inferring how warming affects vegetation have been criticized for decades. In addition, methods that require no electricity may be preferred because of constraints of active warming, e.g. in remote areas. Efforts to overcome the limitations of earlier methods are currently under development, but these approaches have yet to be systematically evaluated side by side. Here, an overview of the benefits and limitations of a selection of innovative empirical techniques to study temperature effects on plants is presented, with a focus on practicality in relatively remote areas without an electric power supply. I focus on methods for: ecosystem aboveground and belowground warming; a fuller exploitation of spatial temperature variation; and long-term monitoring of plant ecological and microevolutionary changes in response to warming. An evaluation of the described methodological set-ups in a synthetic framework along six axes (associated with the consistency of temperature differences, disturbance, costs, confounding factors, spatial scale and versatility) highlights their potential usefulness and power. Hence, further developments of new approaches to empirically assess warming effects on plants can critically stimulate progress in climate-change biology.

Recent climatic drying leads to age-independent growth reductions of white spruce stands in western Canada.

PubMed

Hogg, Edward H; Michaelian, Michael; Hook, Trisha I; Undershultz, Michael E

2017-12-01

Since 2001, climatic conditions have been notably drier than normal across large areas of the western Canadian interior, leading to widespread impacts on the forests of this region. This poses a major concern for the future, given climate change projections for continued warming and drying. We conducted tree-ring analysis in 75 pure stands of white spruce (Picea glauca) across Alberta and west-central Saskatchewan to examine the effects of recent climatic drying on the growth of this important boreal tree species. Allometric equations were used to calculate annual growth in aboveground tree biomass (G BM ) from ring width measurements. Results showed an increasing trend in G BM from the 1960s to the 1990s, followed by a sharp decline during the severe drought of 2001-2002. Of the 75 stands, only 18 recovered sufficiently to cause an increase in mean G BM from the predrought decade of 1991-2000 to the subsequent decade of 2001-2010. The remaining 57 stands exhibited a decline in mean G BM between these decades. Climatic drying was a major cause of the growth decline, as shown by the significant stand-level relationship between percentage change in decadal mean G BM and the change in decadal mean values of a climate moisture index from 1991-2000 to 2001-2010. Subsequent analyses of boreal stands sampled across Alberta during 2015 revealed that white spruce growth had declined even further as drought conditions intensified during 2014-2015. Overall, there was a 38% decrease in mean G BM between 1997 and 2015, but surprisingly, the percentage decrease was not significantly different for young, productive stands compared with older, less productive stands. Thus, stand ageing cannot explain the observed decline in white spruce growth during the past quarter century, suggesting that these forests are at risk if the trend towards more frequent, severe drought continues in the region. © 2017 Her Majesty the Queen in Right of Canada Global Change Biology ©2017 John Wiley

Energy Design Guidelines for High Performance Schools: Hot and Dry Climates.

ERIC Educational Resources Information Center

Department of Energy, Washington, DC. Office of Energy Efficiency and Renewable Energy.

This guide contains recommendations for designing high performance, energy efficient schools located in hot and dry climates. A high performance checklist for designers is included along with several case studies of projects that successfully demonstrated high performance design solutions for hot and dry climates. The guide's 10 sections…

Evidence of a Cooler Continental Climate in East China during the Warm Early Cenozoic.

PubMed

Zhang, Qian-Qian; Smith, Thierry; Yang, Jian; Li, Cheng-Sen

2016-01-01

The early Cenozoic was characterized by a very warm climate especially during the Early Eocene. To understand climatic changes in eastern Asia, we reconstructed the Early Eocene vegetation and climate based on palynological data of a borehole from Wutu coal mine, East China and evaluated the climatic differences between eastern Asia and Central Europe. The Wutu palynological assemblages indicated a warm temperate vegetation succession comprising mixed needle- and broad-leaved forests. Three periods of vegetation succession over time were recognized. The changes of palynomorph relative abundance indicated that period 1 was warm and humid, period 2 was relatively warmer and wetter, and period 3 was cooler and drier again. The climatic parameters estimated by the coexistence approach (CA) suggested that the Early Eocene climate in Wutu was warmer and wetter. Mean annual temperature (MAT) was approximately 16°C and mean annual precipitation (MAP) was 800-1400 mm. Comparison of the Early Eocene climatic parameters of Wutu with those of 39 other fossil floras of different age in East China, reveals that 1) the climate became gradually cooler during the last 65 million years, with MAT dropping by 9.3°C. This cooling trend coincided with the ocean temperature changes but with weaker amplitude; 2) the Early Eocene climate was cooler in East China than in Central Europe; 3) the cooling trend in East China (MAT dropped by 6.9°C) was gentler than in Central Europe (MAT dropped by 13°C) during the last 45 million years.

Evidence of a Cooler Continental Climate in East China during the Warm Early Cenozoic

PubMed Central

Zhang, Qian-Qian; Smith, Thierry; Yang, Jian; Li, Cheng-Sen

2016-01-01

The early Cenozoic was characterized by a very warm climate especially during the Early Eocene. To understand climatic changes in eastern Asia, we reconstructed the Early Eocene vegetation and climate based on palynological data of a borehole from Wutu coal mine, East China and evaluated the climatic differences between eastern Asia and Central Europe. The Wutu palynological assemblages indicated a warm temperate vegetation succession comprising mixed needle- and broad-leaved forests. Three periods of vegetation succession over time were recognized. The changes of palynomorph relative abundance indicated that period 1 was warm and humid, period 2 was relatively warmer and wetter, and period 3 was cooler and drier again. The climatic parameters estimated by the coexistence approach (CA) suggested that the Early Eocene climate in Wutu was warmer and wetter. Mean annual temperature (MAT) was approximately 16°C and mean annual precipitation (MAP) was 800–1400 mm. Comparison of the Early Eocene climatic parameters of Wutu with those of 39 other fossil floras of different age in East China, reveals that 1) the climate became gradually cooler during the last 65 million years, with MAT dropping by 9.3°C. This cooling trend coincided with the ocean temperature changes but with weaker amplitude; 2) the Early Eocene climate was cooler in East China than in Central Europe; 3) the cooling trend in East China (MAT dropped by 6.9°C) was gentler than in Central Europe (MAT dropped by 13°C) during the last 45 million years. PMID:27196048

Dependence of Arctic climate on the latitudinal position of stationary waves and to high-latitudes surface warming

NASA Astrophysics Data System (ADS)

Shin, Yechul; Kang, Sarah M.; Watanabe, Masahiro

2017-12-01

Previous studies suggest large uncertainties in the stationary wave response under global warming. Here, we investigate how the Arctic climate responds to changes in the latitudinal position of stationary waves, and to high-latitudes surface warming that mimics the effect of Arctic sea ice loss under global warming. To generate stationary waves in an atmospheric model coupled to slab ocean, a series of experiments is performed where the thermal forcing with a zonal wavenumber-2 (with zero zonal-mean) is prescribed at the surface at different latitude bands in the Northern Hemisphere. When the stationary waves are generated in the subtropics, the cooling response dominates over the warming response in the lower troposphere due to cloud radiative effects. Then, the low-level baroclinicity is reduced in the subtropics, which gives rise to a poleward shift of the eddy driven jet, thereby inducing substantial cooling in the northern high latitudes. As the stationary waves are progressively generated at higher latitudes, the zonal-mean climate state gradually becomes more similar to the integration with no stationary waves. These differences in the mean climate affect the Arctic climate response to high-latitudes surface warming. Additional surface heating over the Arctic is imposed to the reference climates in which the stationary waves are located at different latitude bands. When the stationary waves are positioned at lower latitudes, the eddy driven jet is located at higher latitude, closer to the prescribed Arctic heating. As baroclinicity is more effectively perturbed, the jet shifts more equatorward that accompanies a larger reduction in the poleward eddy transport of heat and momentum. A stronger eddy-induced descending motion creates greater warming over the Arctic. Our study calls for a more accurate simulation of the present-day stationary wave pattern to enhance the predictability of the Arctic warming response in a changing climate.

The Inequality of Climate Change From 1.5 to 2°C of Global Warming

NASA Astrophysics Data System (ADS)

King, Andrew D.; Harrington, Luke J.

2018-05-01

The Paris Agreement aims to keep global warming well below 2°C above preindustrial levels with a preferred ambitious 1.5°C target. Developing countries, especially small island nations, pressed for the 1.5°C target to be adopted, but who will suffer the largest changes in climate if we miss this target? Here we show that exceeding the 1.5°C global warming target would lead to the poorest experiencing the greatest local climate changes. Under these circumstances greater support for climate adaptation to prevent poverty growth would be required.

``Global Warming/Climate Change'': A Critical Look

NASA Astrophysics Data System (ADS)

Gould, Laurence I.

2011-11-01

There continues to be an increasing number of scientists from around the world who are challenging the dominant claim that has been bolstered by so-called ``consensus'' scientific views -- that dangerous ``global warming/climate change'' is caused primarily by human-produced carbon dioxide. This poster will show scientific evidence contradicting that claim. It will also explain some of the errors that have been introduced from a corruption of the scientific method. (Further information can be found at http://uhaweb.hartford.edu/lgould/)

Water runoff vs modern climatic warming in mountainous cryolithic zone in North-East Russia

NASA Astrophysics Data System (ADS)

Glotov, V. E.; Glotova, L. P.

2018-01-01

The article presents the results of studying the effects of current climatic warming for both surface and subsurface water runoffs in North-East Russia, where the Main Watershed of the Earth separates it into the Arctic and Pacific continental slopes. The process of climatic warming is testified by continuous weather records during 80-100 years and longer periods. Over the Arctic slope and in the northern areas of the Pacific slope, climatic warming results in a decline in a total runoff of rivers whereas the ground-water recharge becomes greater in winter low-level conditions. In the southern Pacific slope and in the Sea of Okhotsk basin, the effect of climatic warming is an overall increase in total runoff including its subsurface constituents. We believe these peculiar characters of river runoff there to be related to the cryolithic zone environments. Over the Arctic slope and the northern Pacific slope, where cryolithic zone is continuous, the total runoff has its subsurface constituent as basically resulting from discharge of ground waters hosted in seasonally thawing rocks. Warmer climatic conditions favor growth of vegetation that needs more water for the processes of evapotranspiration and evaporation from rocky surfaces in summer seasons. In the Sea of Okhotsk basin, where the cryolithic zone is discontinuous, not only ground waters in seasonally thawing layers, but also continuous taliks and subpermafrost waters participate in processes of river recharges. As a result, a greater biological productivity of vegetation cover does not have any effect on ground-water supply and river recharge processes. If a steady climate warming is provided, a continuous cryolithic zone can presumably degrade into a discontinuous and then into an island-type permafrost layer. Under such a scenario, there will be a general increase in the total runoff and its subsurface constituent. From geoecological viewpoints, a greater runoff will have quite positive effects, whereas some

Tropical cyclogenesis in warm climates simulated by a cloud-system resolving model

NASA Astrophysics Data System (ADS)

Fedorov, Alexey V.; Muir, Les; Boos, William R.; Studholme, Joshua

2018-03-01

Here we investigate tropical cyclogenesis in warm climates, focusing on the effect of reduced equator-to-pole temperature gradient relevant to past equable climates and, potentially, to future climate change. Using a cloud-system resolving model that explicitly represents moist convection, we conduct idealized experiments on a zonally periodic equatorial β-plane stretching from nearly pole-to-pole and covering roughly one-fifth of Earth's circumference. To improve the representation of tropical cyclogenesis and mean climate at a horizontal resolution that would otherwise be too coarse for a cloud-system resolving model (15 km), we use the hypohydrostatic rescaling of the equations of motion, also called reduced acceleration in the vertical. The simulations simultaneously represent the Hadley circulation and the intertropical convergence zone, baroclinic waves in mid-latitudes, and a realistic distribution of tropical cyclones (TCs), all without use of a convective parameterization. Using this model, we study the dependence of TCs on the meridional sea surface temperature gradient. When this gradient is significantly reduced, we find a substantial increase in the number of TCs, including a several-fold increase in the strongest storms of Saffir-Simpson categories 4 and 5. This increase occurs as the mid-latitudes become a new active region of TC formation and growth. When the climate warms we also see convergence between the physical properties and genesis locations of tropical and warm-core extra-tropical cyclones. While end-members of these types of storms remain very distinct, a large distribution of cyclones forming in the subtropics and mid-latitudes share properties of the two.

Geoengineering the Climate: Approaches to Counterbalancing Global Warming

NASA Astrophysics Data System (ADS)

MacCracken, M. C.

2005-12-01

For the past two hundred years, the inadvertent release of carbon dioxide and other radiatively active gases and aerosols, particularly as a result of combustion of fossil fuels and changes in land cover, have been contributing to global climate change. Global warming to date is approaching 1°C, and this is being accompanied by reduced sea ice, rising sea level, shifting ecosystems and more. Rather than sharply curtailing use of fossil fuels in order to reduce CO2 emissions and eventually eliminate the net human influence on global climate, a number of approaches have been suggested that are intended to advertently modify the climate in a manner to counter-balance the warming influence of greenhouse gas emissions. One general type of approach is carbon sequestration, which focuses on capturing the CO2 and then sequestering it underground or in the ocean. This can be done at the source of emission, by pulling the CO2 out of the atmosphere through some chemical process, or by enhancing the natural processes that remove CO2 from the atmosphere, for example by fertilizing the oceans with iron. A second general approach to geoengineering the climate is to lower the warming influence of the incoming solar radiation by an amount equivalent to the energy captured by the CO2-induced enhancement of the greenhouse effect. Proposals have been made to do this by locating a deflector at the Earth-Sun Lagrange point, lofting many thousands of near-Earth mirrors, injecting aerosols into the stratosphere, or by increasing the surface albedo. A third general approach is to alter natural Earth system processes in ways that would counterbalance the effects of the warming. Among suggested approaches are constructing dams to block various ocean passages, oceanic films to limit evaporation and water vapor feedback, and even, at small scale, to insulate mountain glaciers to prevent melting. Each of these approaches has its advantages, ranging from simplicity to reversibility, and

Forests synchronize their growth in contrasting Eurasian regions in response to climate warming.

PubMed

Shestakova, Tatiana A; Gutiérrez, Emilia; Kirdyanov, Alexander V; Camarero, Jesús Julio; Génova, Mar; Knorre, Anastasia A; Linares, Juan Carlos; Resco de Dios, Víctor; Sánchez-Salguero, Raúl; Voltas, Jordi

2016-01-19

Forests play a key role in the carbon balance of terrestrial ecosystems. One of the main uncertainties in global change predictions lies in how the spatiotemporal dynamics of forest productivity will be affected by climate warming. Here we show an increasing influence of climate on the spatial variability of tree growth during the last 120 y, ultimately leading to unprecedented temporal coherence in ring-width records over wide geographical scales (spatial synchrony). Synchrony in growth patterns across cold-constrained (central Siberia) and drought-constrained (Spain) Eurasian conifer forests have peaked in the early 21st century at subcontinental scales (∼ 1,000 km). Such enhanced synchrony is similar to that observed in trees co-occurring within a stand. In boreal forests, the combined effects of recent warming and increasing intensity of climate extremes are enhancing synchrony through an earlier start of wood formation and a stronger impact of year-to-year fluctuations of growing-season temperatures on growth. In Mediterranean forests, the impact of warming on synchrony is related mainly to an advanced onset of growth and the strengthening of drought-induced growth limitations. Spatial patterns of enhanced synchrony represent early warning signals of climate change impacts on forest ecosystems at subcontinental scales.

Forests synchronize their growth in contrasting Eurasian regions in response to climate warming

PubMed Central

Shestakova, Tatiana A.; Gutiérrez, Emilia; Kirdyanov, Alexander V.; Camarero, Jesús Julio; Génova, Mar; Knorre, Anastasia A.; Linares, Juan Carlos; Sánchez-Salguero, Raúl; Voltas, Jordi

2016-01-01

Forests play a key role in the carbon balance of terrestrial ecosystems. One of the main uncertainties in global change predictions lies in how the spatiotemporal dynamics of forest productivity will be affected by climate warming. Here we show an increasing influence of climate on the spatial variability of tree growth during the last 120 y, ultimately leading to unprecedented temporal coherence in ring-width records over wide geographical scales (spatial synchrony). Synchrony in growth patterns across cold-constrained (central Siberia) and drought-constrained (Spain) Eurasian conifer forests have peaked in the early 21st century at subcontinental scales (∼1,000 km). Such enhanced synchrony is similar to that observed in trees co-occurring within a stand. In boreal forests, the combined effects of recent warming and increasing intensity of climate extremes are enhancing synchrony through an earlier start of wood formation and a stronger impact of year-to-year fluctuations of growing-season temperatures on growth. In Mediterranean forests, the impact of warming on synchrony is related mainly to an advanced onset of growth and the strengthening of drought-induced growth limitations. Spatial patterns of enhanced synchrony represent early warning signals of climate change impacts on forest ecosystems at subcontinental scales. PMID:26729860

Differential climate impacts for policy-relevant limits to global warming: the case of 1.5 °C and 2 °C

NASA Astrophysics Data System (ADS)

Schleussner, C.-F.; Lissner, T. K.; Fischer, E. M.; Wohland, J.; Perrette, M.; Golly, A.; Rogelj, J.; Childers, K.; Schewe, J.; Frieler, K.; Mengel, M.; Hare, W.; Schaeffer, M.

2015-11-01

Robust appraisals of climate impacts at different levels of global-mean temperature increase are vital to guide assessments of dangerous anthropogenic interference with the climate system. Currently, two such levels are discussed in the context of the international climate negotiations as long-term global temperature goals: a below 2 °C and a 1.5 °C limit in global-mean temperature rise above pre-industrial levels. Despite the prominence of these two temperature limits, a comprehensive assessment of the differences in climate impacts at these levels is still missing. Here we provide an assessment of key impacts of climate change at warming levels of 1.5 °C and 2 °C, including extreme weather events, water availability, agricultural yields, sea-level rise and risk of coral reef loss. Our results reveal substantial differences in impacts between 1.5 °C and 2 °C. For heat-related extremes, the additional 0.5 °C increase in global-mean temperature marks the difference between events at the upper limit of present-day natural variability and a new climate regime, particularly in tropical regions. Similarly, this warming difference is likely to be decisive for the future of tropical coral reefs. In a scenario with an end-of-century warming of 2 °C, virtually all tropical coral reefs are projected to be at risk of severe degradation due to temperature induced bleaching from 2050 onwards. This fraction is reduced to about 90 % in 2050 and projected to decline to 70 % by 2100 for a 1.5 °C scenario. Analyses of precipitation-related impacts reveal distinct regional differences and several hot-spots of change emerge. Regional reduction in median water availability for the Mediterranean is found to nearly double from 9 to 17 % between 1.5 °C and 2 °C, and the projected lengthening of regional dry spells increases from 7 % longer to 11 %. Projections for agricultural yields differ between crop types as well as world regions. While some (in particular high

Spatial stabilization and intensification of moistening and drying rate patterns under future climate change

NASA Astrophysics Data System (ADS)

Chavaillaz, Y.; Joussaume, S.; Bony, S.; Braconnot, P.

2015-12-01

Most climate studies characterize the future climate change by considering the evolution between a fixed current baseline and the future. It emphasizes an increase of future precipitation changes with global warming. Here we use an alternative approach that considers rate of change indicators related to precipitation using projections of an ensemble of General Circulation Models. The rate is defined by the difference between two subsequent 20-year periods. This approach can be relevant to impacts affecting upcoming generations, and to their continuous adaptation towards a changing target. Under the strongest emission pathway (RCP8.5), moistening and drying rates strongly increase at the global scale. As we move further over the twenty-first century, more and more regions exhibit substantial rates. These regions are modified over time due to spatial variability of precipitation. However, we show that they tend to become more geographically stationary through the century, leading to persisting trends at several places over the globe. Whilst global warming is accelerating, this spatial stabilization is due to the decreasing relative influence of global circulation in precipitation changes compared to thermodynamic processes. In specific regions, the combination of intensification and persistence of such substantial rates should be considered in the framework of future impact studies (i.e. the Mediterranean Sea, Central America, South Asia and the Arctic). These trends are already visible in the current period, but could almost disappear if strong mitigation policies (RCP2.6) were quickly implemented.

Global warming induced hybrid rainy seasons in the Sahel

NASA Astrophysics Data System (ADS)

Salack, Seyni; Klein, Cornelia; Giannini, Alessandra; Sarr, Benoit; Worou, Omonlola N.; Belko, Nouhoun; Bliefernicht, Jan; Kunstman, Harald

2016-10-01

The small rainfall recovery observed over the Sahel, concomitant with a regional climate warming, conceals some drought features that exacerbate food security. The new rainfall features include false start and early cessation of rainy seasons, increased frequency of intense daily rainfall, increasing number of hot nights and warm days and a decreasing trend in diurnal temperature range. Here, we explain these mixed dry/wet seasonal rainfall features which are called hybrid rainy seasons by delving into observed data consensus on the reduction in rainfall amount, its spatial coverage, timing and erratic distribution of events, and other atmospheric variables crucial in agro-climatic monitoring and seasonal forecasting. Further composite investigations of seasonal droughts, oceans warming and the regional atmospheric circulation nexus reveal that the low-to-mid-level atmospheric winds pattern, often stationary relative to either strong or neutral El-Niño-Southern-Oscillations drought patterns, associates to basin warmings in the North Atlantic and the Mediterranean Sea to trigger hybrid rainy seasons in the Sahel. More challenging to rain-fed farming systems, our results suggest that these new rainfall conditions will most likely be sustained by global warming, reshaping thereby our understanding of food insecurity in this region.

Global warming and allergy in Asia Minor.

PubMed

Bajin, Munir Demir; Cingi, Cemal; Oghan, Fatih; Gurbuz, Melek Kezban

2013-01-01

The earth is warming, and it is warming quickly. Epidemiological studies have demonstrated that global warming is correlated with the frequency of pollen-induced respiratory allergy and allergic diseases. There is a body of evidence suggesting that the prevalence of allergic diseases induced by pollens is increasing in developed countries, a trend that is also evident in the Mediterranean area. Because of its mild winters and sunny days with dry summers, the Mediterranean area is different from the areas of central and northern Europe. Classical examples of allergenic pollen-producing plants of the Mediterranean climate include Parietaria, Olea and Cupressaceae. Asia Minor is a Mediterranean region that connects Asia and Europe, and it includes considerable coastal areas. Gramineae pollens are the major cause of seasonal allergic rhinitis in Asia Minor, affecting 1.3-6.4 % of the population, in accordance with other European regions. This article emphasizes the importance of global climate change and anticipated increases in the prevalence and severity of allergic disease in Asia Minor, mediated through worsening air pollution and altered local and regional pollen production, from an otolaryngologic perspective.

Climate change, global warming and coral reefs: modelling the effects of temperature.

PubMed

Crabbe, M James C

2008-10-01

Climate change and global warming have severe consequences for the survival of scleractinian (reef-building) corals and their associated ecosystems. This review summarizes recent literature on the influence of temperature on coral growth, coral bleaching, and modelling the effects of high temperature on corals. Satellite-based sea surface temperature (SST) and coral bleaching information available on the internet is an important tool in monitoring and modelling coral responses to temperature. Within the narrow temperature range for coral growth, corals can respond to rate of temperature change as well as to temperature per se. We need to continue to develop models of how non-steady-state processes such as global warming and climate change will affect coral reefs.

Climate warming: a loss of variation in populations can accompany reproductive shifts.

PubMed

Massot, Manuel; Legendre, Stéphane; Fédérici, Pierre; Clobert, Jean

2017-09-01

The most documented response of organisms to climate warming is a change in the average timing of seasonal activities (phenology). Although we know that these average changes can differ among species and populations, we do not know whether climate warming impacts within-population variation in phenology. Using data from five study sites collected during a 13-year survey, we found that the increase in spring temperatures is associated with a reproductive advance of 10 days in natural populations of common lizards (Zootoca vivipara). Interestingly, we show a correlated loss of variation in reproductive dates within populations. As illustrated by a model, this shortening of the reproductive period can have significant negative effects on population dynamics. Consequently, we encourage tests in other species to assess the generality of decreased variation in phenological responses to climate change. © 2017 The Authors Ecology Letters published by CNRS and John Wiley & Sons Ltd.

Can Regional Climate Models Improve Warm Season Forecasts in the North American Monsoon Region?

NASA Astrophysics Data System (ADS)

Dominguez, F.; Castro, C. L.

2009-12-01

The goal of this work is to improve warm season forecasts in the North American Monsoon Region. To do this, we are dynamically downscaling warm season CFS (Climate Forecast System) reforecasts from 1982-2005 for the contiguous U.S. using the Weather Research and Forecasting (WRF) regional climate model. CFS is the global coupled ocean-atmosphere model used by the Climate Prediction Center (CPC), a branch of the National Center for Environmental Prediction (NCEP), to provide official U.S. seasonal climate forecasts. Recently, NCEP has produced a comprehensive long-term retrospective ensemble CFS reforecasts for the years 1980-2005. These reforecasts show that CFS model 1) has an ability to forecast tropical Pacific SSTs and large-scale teleconnection patterns, at least as evaluated for the winter season; 2) has greater skill in forecasting winter than summer climate; and 3) demonstrates an increase in skill when a greater number of ensembles members are used. The decrease in CFS skill during the warm season is due to the fact that the physical mechanisms of rainfall at this time are more related to mesoscale processes, such as the diurnal cycle of convection, low-level moisture transport, propagation and organization of convection, and surface moisture recycling. In general, these are poorly represented in global atmospheric models. Preliminary simulations for years with extreme summer climate conditions in the western and central U.S. (specifically 1988 and 1993) show that CFS-WRF simulations can provide a more realistic representation of convective rainfall processes. Thus a RCM can potentially add significant value in climate forecasting of the warm season provided the downscaling methodology incorporates the following: 1) spectral nudging to preserve the variability in the large scale circulation while still permitting the development of smaller-scale variability in the RCM; and 2) use of realistic soil moisture initial condition, in this case provided by the

Multisectoral climate impact hotspots in a warming world.

PubMed

Piontek, Franziska; Müller, Christoph; Pugh, Thomas A M; Clark, Douglas B; Deryng, Delphine; Elliott, Joshua; Colón González, Felipe de Jesus; Flörke, Martina; Folberth, Christian; Franssen, Wietse; Frieler, Katja; Friend, Andrew D; Gosling, Simon N; Hemming, Deborah; Khabarov, Nikolay; Kim, Hyungjun; Lomas, Mark R; Masaki, Yoshimitsu; Mengel, Matthias; Morse, Andrew; Neumann, Kathleen; Nishina, Kazuya; Ostberg, Sebastian; Pavlick, Ryan; Ruane, Alex C; Schewe, Jacob; Schmid, Erwin; Stacke, Tobias; Tang, Qiuhong; Tessler, Zachary D; Tompkins, Adrian M; Warszawski, Lila; Wisser, Dominik; Schellnhuber, Hans Joachim

2014-03-04

The impacts of global climate change on different aspects of humanity's diverse life-support systems are complex and often difficult to predict. To facilitate policy decisions on mitigation and adaptation strategies, it is necessary to understand, quantify, and synthesize these climate-change impacts, taking into account their uncertainties. Crucial to these decisions is an understanding of how impacts in different sectors overlap, as overlapping impacts increase exposure, lead to interactions of impacts, and are likely to raise adaptation pressure. As a first step we develop herein a framework to study coinciding impacts and identify regional exposure hotspots. This framework can then be used as a starting point for regional case studies on vulnerability and multifaceted adaptation strategies. We consider impacts related to water, agriculture, ecosystems, and malaria at different levels of global warming. Multisectoral overlap starts to be seen robustly at a mean global warming of 3 °C above the 1980-2010 mean, with 11% of the world population subject to severe impacts in at least two of the four impact sectors at 4 °C. Despite these general conclusions, we find that uncertainty arising from the impact models is considerable, and larger than that from the climate models. In a low probability-high impact worst-case assessment, almost the whole inhabited world is at risk for multisectoral pressures. Hence, there is a pressing need for an increased research effort to develop a more comprehensive understanding of impacts, as well as for the development of policy measures under existing uncertainty.

Multisectoral Climate Impact Hotspots in a Warming World

NASA Technical Reports Server (NTRS)

Piontek, Franziska; Mueller, Christoph; Pugh, Thomas A. M.; Clark, Douglas B.; Deryng, Delphine; Elliott, Joshua; deJesusColonGonzalez, Felipe; Floerke, Martina; Folberth, Christian; Franssen, Wietse;

California golden trout and climate change: Is their stream habitat vulnerable to climate warming?

Treesearch

Kathleen R. Matthews

2010-01-01

The California golden trout (CGT) Oncorhynchus mykiss aguabonita is one of the few native high-elevation fish in the Sierra Nevada. They are already in trouble because of exotic trout, genetic introgression, and degraded habitat, and now face further stress from climate warming. Their native habitat on the Kern Plateau meadows mostly in the Golden...

Host and parasite thermal ecology jointly determine the effect of climate warming on epidemic dynamics.

PubMed

Gehman, Alyssa-Lois M; Hall, Richard J; Byers, James E

2018-01-23

Host-parasite systems have intricately coupled life cycles, but each interactor can respond differently to changes in environmental variables like temperature. Although vital to predicting how parasitism will respond to climate change, thermal responses of both host and parasite in key traits affecting infection dynamics have rarely been quantified. Through temperature-controlled experiments on an ectothermic host-parasite system, we demonstrate an offset in the thermal optima for survival of infected and uninfected hosts and parasite production. We combine experimentally derived thermal performance curves with field data on seasonal host abundance and parasite prevalence to parameterize an epidemiological model and forecast the dynamical responses to plausible future climate-warming scenarios. In warming scenarios within the coastal southeastern United States, the model predicts sharp declines in parasite prevalence, with local parasite extinction occurring with as little as 2 °C warming. The northern portion of the parasite's current range could experience local increases in transmission, but assuming no thermal adaptation of the parasite, we find no evidence that the parasite will expand its range northward under warming. This work exemplifies that some host populations may experience reduced parasitism in a warming world and highlights the need to measure host and parasite thermal performance to predict infection responses to climate change.

Changing forest water yields in response to climate warming: results from long-term experimental watershed sites across North America

Treesearch

Irena F. Creed; Adam T. Spargo; Julia A. Jones; Jim M. Buttle; Mary B. Adams; Fred D. Beall; Eric G. Booth; John L. Campbell; Dave Clow; Kelly Elder; Mark B. Green; Nancy B. Grimm; Chelcy Miniat; Patricia Ramlal; Amartya Saha; Stephen Sebestyen; Dave Spittlehouse; Shannon Sterling; Mark W. Williams; Rita Winkler; Huaxia Yao

2014-01-01

Climate warming is projected to affect forest water yields but the effects are expected to vary.We investigated how forest type and age affect water yield resilience to climate warming. To answer this question, we examined the variability in historical water yields at long-term experimental catchments across Canada and the United States over 5-year cool and warm...

Separating climate change signals into thermodynamic, lapse-rate and circulation effects: theory and application to the European summer climate

NASA Astrophysics Data System (ADS)

Kröner, Nico; Kotlarski, Sven; Fischer, Erich; Lüthi, Daniel; Zubler, Elias; Schär, Christoph

2017-05-01

Climate models robustly project a strong overall summer warming across Europe showing a characteristic north-south gradient with enhanced warming and drying in southern Europe. However, the processes that are responsible for this pattern are not fully understood. We here employ an extended surrogate or pseudo-warming approach to disentangle the contribution of different mechanisms to this response pattern. The basic idea of the surrogate technique is to use a regional climate model and apply a large-scale warming to the lateral boundary conditions of a present-day reference simulation, while maintaining the relative humidity (and thus implicitly increasing the specific moisture content). In comparison to previous studies, our approach includes two important extensions: first, different vertical warming profiles are applied in order to separate the effects of a mean warming from lapse-rate effects. Second, a twin-design is used, in which the climate change signals are not only added to present-day conditions, but also subtracted from a scenario experiment. We demonstrate that these extensions provide an elegant way to separate the full climate change signal into contributions from large-scale thermodynamic (TD), lapse-rate (LR), and circulation and other remaining effects (CO). The latter in particular include changes in land-ocean contrast and spatial variations of the SST warming patterns. We find that the TD effect yields a large-scale warming across Europe with no distinct latitudinal gradient. The LR effect, which is quantified for the first time in our study, leads to a stronger warming and some drying in southern Europe. It explains about 50 % of the warming amplification over the Iberian Peninsula, thus demonstrating the important role of lapse-rate changes. The effect is linked to an extending Hadley circulation. The CO effect as inherited from the driving GCM is shown to further amplify the north-south temperature change gradient. In terms of mean summer

Fine-scale climate change: modelling spatial variation in biologically meaningful rates of warming.

PubMed

Maclean, Ilya M D; Suggitt, Andrew J; Wilson, Robert J; Duffy, James P; Bennie, Jonathan J

2017-01-01

The existence of fine-grain climate heterogeneity has prompted suggestions that species may be able to survive future climate change in pockets of suitable microclimate, termed 'microrefugia'. However, evidence for microrefugia is hindered by lack of understanding of how rates of warming vary across a landscape. Here, we present a model that is applied to provide fine-grained, multidecadal estimates of temperature change based on the underlying physical processes that influence microclimate. Weather station and remotely derived environmental data were used to construct physical variables that capture the effects of terrain, sea surface temperatures, altitude and surface albedo on local temperatures, which were then calibrated statistically to derive gridded estimates of temperature. We apply the model to the Lizard Peninsula, United Kingdom, to provide accurate (mean error = 1.21 °C; RMS error = 1.63 °C) hourly estimates of temperature at a resolution of 100 m for the period 1977-2014. We show that rates of warming vary across a landscape primarily due to long-term trends in weather conditions. Total warming varied from 0.87 to 1.16 °C, with the slowest rates of warming evident on north-east-facing slopes. This variation contributed to substantial spatial heterogeneity in trends in bioclimatic variables: for example, the change in the length of the frost-free season varied from +11 to -54 days and the increase in annual growing degree-days from 51 to 267 °C days. Spatial variation in warming was caused primarily by a decrease in daytime cloud cover with a resulting increase in received solar radiation, and secondarily by a decrease in the strength of westerly winds, which has amplified the effects on temperature of solar radiation on west-facing slopes. We emphasize the importance of multidecadal trends in weather conditions in determining spatial variation in rates of warming, suggesting that locations experiencing least warming may not remain

Insolation driven biomagnetic response to the Holocene Warm Period in semi-arid East Asia

NASA Astrophysics Data System (ADS)

Liu, Suzhen; Deng, Chenglong; Xiao, Jule; Li, Jinhua; Paterson, Greig A.; Chang, Liao; Yi, Liang; Qin, Huafeng; Pan, Yongxin; Zhu, Rixiang

2015-01-01

The Holocene Warm Period (HWP) provides valuable insights into the climate system and biotic responses to environmental variability and thus serves as an excellent analogue for future global climate changes. Here we document, for the first time, that warm and wet HWP conditions were highly favourable for magnetofossil proliferation in the semi-arid Asian interior. The pronounced increase of magnetofossil concentrations at ~9.8 ka and decrease at ~5.9 ka in Dali Lake coincided respectively with the onset and termination of the HWP, and are respectively linked to increased nutrient supply due to postglacial warming and poor nutrition due to drying at ~6 ka in the Asian interior. The two-stage transition at ~7.7 ka correlates well with increased organic carbon in middle HWP and suggests that improved climate conditions, leading to high quality nutrient influx, fostered magnetofossil proliferation. Our findings represent an excellent lake record in which magnetofossil abundance is, through nutrient availability, controlled by insolation driven climate changes.

Insolation driven biomagnetic response to the Holocene Warm Period in semi-arid East Asia.

PubMed

Liu, Suzhen; Deng, Chenglong; Xiao, Jule; Li, Jinhua; Paterson, Greig A; Chang, Liao; Yi, Liang; Qin, Huafeng; Pan, Yongxin; Zhu, Rixiang

2015-01-23

The Holocene Warm Period (HWP) provides valuable insights into the climate system and biotic responses to environmental variability and thus serves as an excellent analogue for future global climate changes. Here we document, for the first time, that warm and wet HWP conditions were highly favourable for magnetofossil proliferation in the semi-arid Asian interior. The pronounced increase of magnetofossil concentrations at ~9.8 ka and decrease at ~5.9 ka in Dali Lake coincided respectively with the onset and termination of the HWP, and are respectively linked to increased nutrient supply due to postglacial warming and poor nutrition due to drying at ~6 ka in the Asian interior. The two-stage transition at ~7.7 ka correlates well with increased organic carbon in middle HWP and suggests that improved climate conditions, leading to high quality nutrient influx, fostered magnetofossil proliferation. Our findings represent an excellent lake record in which magnetofossil abundance is, through nutrient availability, controlled by insolation driven climate changes.

Indirect chemical effects of methane on climate warming

NASA Astrophysics Data System (ADS)

Lelieveld, Jos; Crutzen, Paul J.

1992-01-01

METHANE concentrations in the atmosphere have increased from about 0.75 to 1.7 p.p.m.v. since pre-industrial times1,2. The current annual rate of increase of about 0.8% yr-1 (ref. 2) is due to increases in industrial and agricultural emissions. This increase in atmospheric methane concentrations not only influences the climate directly, but also indirectly through chemical reactions. Here we show that the climate effects of methane's atmospheric chemistry have previously been overestimated, notably by the Inter-governmental Panel on Climate Change (IPCC)3, largely owing to neglect of the height dependence of certain atmospheric radiative processes. Using available estimates of fossil-fuel-related leaks of methane, our results show that switching from coal and oil to natural gas as an energy source would reduce climate warming. A significant fraction of methane emissions cannot, however, be accounted for by known sources; should leakages from gas production and distribution be underestimated for some countries, then it might be unwise to switch to using natural gas.

Resilience of Alaska's boreal forest to climate change

Treesearch

F.S. Chapin; A.D. McGuire; R.W. Ruess; T.N. Hollingsworth; M.C. Mack; J.F. Johnstone; E.S. Kasischke; E.S. Euskirchen; J.B. Jones; M.T. Jorgenson; K. Kielland; G.P. Kofinas; M.R. Turetsky; J. Yarie; A.H. Lloyd; D.L. Taylor

2010-01-01

This paper assesses the resilience of Alaska's boreal forest system to rapid climatic change. Recent warming is associated with reduced growth of dominant tree species, plant disease and insect outbreaks, warming and thawing of permafrost, drying of lakes, increased wildfire extent, increased postfire recruitment of deciduous trees, and reduced safety of hunters...

Does physiological acclimation to climate warming stabilize the ratio of canopy respiration to photosynthesis?

PubMed

Drake, John E; Tjoelker, Mark G; Aspinwall, Michael J; Reich, Peter B; Barton, Craig V M; Medlyn, Belinda E; Duursma, Remko A

2016-08-01

Given the contrasting short-term temperature dependences of gross primary production (GPP) and autotrophic respiration, the fraction of GPP respired by trees is predicted to increase with warming, providing a positive feedback to climate change. However, physiological acclimation may dampen or eliminate this response. We measured the fluxes of aboveground respiration (Ra ), GPP and their ratio (Ra /GPP) in large, field-grown Eucalyptus tereticornis trees exposed to ambient or warmed air temperatures (+3°C). We report continuous measurements of whole-canopy CO2 exchange, direct temperature response curves of leaf and canopy respiration, leaf and branch wood respiration, and diurnal photosynthetic measurements. Warming reduced photosynthesis, whereas physiological acclimation prevented a coincident increase in Ra . Ambient and warmed trees had a common nonlinear relationship between the fraction of GPP that was respired above ground (Ra /GPP) and the mean daily temperature. Thus, warming significantly increased Ra /GPP by moving plants to higher positions on the shared Ra /GPP vs daily temperature relationship, but this effect was modest and only notable during hot conditions. Despite the physiological acclimation of autotrophic respiration to warming, increases in temperature and the frequency of heat waves may modestly increase tree Ra /GPP, contributing to a positive feedback between climate warming and atmospheric CO2 accumulation. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Responses of spring phenology to climate warming reduced over the past decades

NASA Astrophysics Data System (ADS)

Fu, Yongshuo. H.; Zhao, hongfang; piao, Shilong; Peaucelle, Marc; Peng, Shushi; Zhou, Guiyun; Ciais, Philippe; Huang, Mengtian; Menzel, Annette; Penuelas, Josep; Song, Yang; Vitasse, Yann; Zeng, Zhenzhong; Janssens, Ivan. A.

2016-04-01

The phenology of spring leaf unfolding is one of the key indicators of the climate change on ecosystems, and influences regional and hemispheric-scale carbon balances and plant-animal interactions. Changes in the phenology of spring leaf unfolding can also exert biophysical feedbacks on climate by modifying the surface albedo and energy budget. Recent studies have reported significant advances in spring phenology as a result of warming in most northern hemisphere regions. Climate warming is projected to further increase, but the future evolution of the phenology of spring leaf unfolding remains uncertain - in view of the imperfect understanding of how the underlying mechanisms respond to environmental stimuli. In addition, the relative contributions of each environmental stimulus, which together define the apparent temperature sensitivity of the phenology of spring leaf unfolding (advances in days per degree Celsius warming, ST), may also change over time. An improved characterization of the variation in phenological responses to spring temperature is thus valuable, provided that it addresses temporal and spatial scales relevant for regional projections. Using long-term in situ observations of leaf unfolding for seven dominant European tree species at 1,245 sites, we show here that the apparent response of leaf unfolding to climate warming (ST, expressed in days advance per ° C) has significantly decreased from 1980 to 2013 in all monitored tree species. Averaged across all species and sites, ST decreased by 40% from 4.0 ± 1.8 days ° C-1 during 1980-1994 to 2.3 ± 1.6 days ° C-1 during 1999-2013. The declining ST was also simulated by chilling-based phenology models, albeit with a weaker decline (24%-30%) than observed in situ. The reduction in ST is likely to be partly attributable to reduced chilling. Nonetheless, other mechanisms may also play a role, such as 'photoperiod limitation' mechanisms that may become ultimately limiting when leaf unfolding dates

Climate warming increases biological control agent impact on a non-target species

PubMed Central

Lu, Xinmin; Siemann, Evan; He, Minyan; Wei, Hui; Shao, Xu; Ding, Jianqing

2015-01-01

Climate change may shift interactions of invasive plants, herbivorous insects and native plants, potentially affecting biological control efficacy and non-target effects on native species. Here, we show how climate warming affects impacts of a multivoltine introduced biocontrol beetle on the non-target native plant Alternanthera sessilis in China. In field surveys across a latitudinal gradient covering their full distributions, we found beetle damage on A. sessilis increased with rising temperature and plant life history changed from perennial to annual. Experiments showed that elevated temperature changed plant life history and increased insect overwintering, damage and impacts on seedling recruitment. These results suggest that warming can shift phenologies, increase non-target effect magnitude and increase non-target effect occurrence by beetle range expansion to additional areas where A. sessilis occurs. This study highlights the importance of understanding how climate change affects species interactions for future biological control of invasive species and conservation of native species. PMID:25376303

Regional Climate Impacts of Stabilizing Global Warming at 1.5 K Using Solar Geoengineering

NASA Astrophysics Data System (ADS)

Jones, Anthony C.; Hawcroft, Matthew K.; Haywood, James M.; Jones, Andy; Guo, Xiaoran; Moore, John C.

2018-02-01

The 2015 Paris Agreement aims to limit global warming to well below 2 K above preindustrial levels, and to pursue efforts to limit global warming to 1.5 K, in order to avert dangerous climate change. However, current greenhouse gas emissions targets are more compatible with scenarios exhibiting end-of-century global warming of 2.6-3.1 K, in clear contradiction to the 1.5 K target. In this study, we use a global climate model to investigate the climatic impacts of using solar geoengineering by stratospheric aerosol injection to stabilize global-mean temperature at 1.5 K for the duration of the 21st century against three scenarios spanning the range of plausible greenhouse gas mitigation pathways (RCP2.6, RCP4.5, and RCP8.5). In addition to stabilizing global mean temperature and offsetting both Arctic sea-ice loss and thermosteric sea-level rise, we find that solar geoengineering could effectively counteract enhancements to the frequency of extreme storms in the North Atlantic and heatwaves in Europe, but would be less effective at counteracting hydrological changes in the Amazon basin and North Atlantic storm track displacement. In summary, solar geoengineering may reduce global mean impacts but is an imperfect solution at the regional level, where the effects of climate change are experienced. Our results should galvanize research into the regionality of climate responses to solar geoengineering.

Responses of community-level plant-insect interactions to climate warming in a meadow steppe.

PubMed

Zhu, Hui; Zou, Xuehui; Wang, Deli; Wan, Shiqiang; Wang, Ling; Guo, Jixun

2015-12-21

Climate warming may disrupt trophic interactions, consequently influencing ecosystem functioning. Most studies have concentrated on the temperature-effects on plant-insect interactions at individual and population levels, with a particular emphasis on changes in phenology and distribution. Nevertheless, the available evidence from the community level is limited. A 3-year field manipulative experiment was performed to test potential responses of plant and insect communities, and plant-insect interactions, to elevated temperature in a meadow steppe. Warming increased the biomass of plant community and forbs, and decreased grass biomass, indicating a shift from grass-dominant to grass-forb mixed plant community. Reduced abundance of the insect community under warming, particularly the herbivorous insects, was attributed to lower abundance of Euchorthippus unicolor and a Cicadellidae species resulting from lower food availability and higher defensive herbivory. Lower herbivore abundance caused lower predator species richness because of reduced prey resources and contributed to an overall decrease in insect species richness. Interestingly, warming enhanced the positive relationship between insect and plant species richness, implying that the strength of the plant-insect interactions was altered by warming. Our results suggest that alterations to plant-insect interactions at a community level under climate warming in grasslands may be more important and complex than previously thought.

Past and future warming of a deep European lake (Lake Lugano): What are the climatic drivers?

USGS Publications Warehouse

Lepori, Fabio; Roberts, James J.

2015-01-01

We used four decades (1972–2013) of temperature data from Lake Lugano, Switzerland and Italy, to address the hypotheses that: [i] the lake has been warming; [ii] part of the warming reflects global trends and is independent from climatic oscillations and [iii] the lake will continue to warm until the end of the 21st century. During the time spanned by our data, the surface waters of the lake (0–5 m) warmed at rates of 0.2–0.9 °C per decade, depending on season. The temperature of the deep waters (50-m bottom) displayed a rising trend in a meromictic basin of the lake and a sawtooth pattern in the other basin, which is holomictic. Long-term variation in surfacewater temperature correlated to global warming and multidecadal variation in two climatic oscillations, the Atlantic Multidecadal Oscillation (AMO) and the East Atlantic Pattern (EA).However, we did not detect an influence of the EA on the lake's temperature (as separate from the effect of global warming). Moreover, the effect of the AMO, estimated to a maximum of +1 °C, was not sufficient to explain the observed temperature increase (+2–3 °C in summer). Based on regional climate projections, we predicted that the lake will continue to warm at least until the end of the 21st century. Our results strongly suggest that the warming of Lake Lugano is tied to globalclimate change. To sustain current ecosystem conditions in Lake Lugano, we suggest that manage- ment plans that curtail eutrophication and (or) mitigation of global warming be pursued.

A global experiment suggests climate warming will not accelerate litter decomposition in streams but might reduce carbon sequestration.

PubMed

Boyero, Luz; Pearson, Richard G; Gessner, Mark O; Barmuta, Leon A; Ferreira, Verónica; Graça, Manuel A S; Dudgeon, David; Boulton, Andrew J; Callisto, Marcos; Chauvet, Eric; Helson, Julie E; Bruder, Andreas; Albariño, Ricardo J; Yule, Catherine M; Arunachalam, Muthukumarasamy; Davies, Judy N; Figueroa, Ricardo; Flecker, Alexander S; Ramírez, Alonso; Death, Russell G; Iwata, Tomoya; Mathooko, Jude M; Mathuriau, Catherine; Gonçalves, José F; Moretti, Marcelo S; Jinggut, Tajang; Lamothe, Sylvain; M'Erimba, Charles; Ratnarajah, Lavenia; Schindler, Markus H; Castela, José; Buria, Leonardo M; Cornejo, Aydeé; Villanueva, Verónica D; West, Derek C

2011-03-01

The decomposition of plant litter is one of the most important ecosystem processes in the biosphere and is particularly sensitive to climate warming. Aquatic ecosystems are well suited to studying warming effects on decomposition because the otherwise confounding influence of moisture is constant. By using a latitudinal temperature gradient in an unprecedented global experiment in streams, we found that climate warming will likely hasten microbial litter decomposition and produce an equivalent decline in detritivore-mediated decomposition rates. As a result, overall decomposition rates should remain unchanged. Nevertheless, the process would be profoundly altered, because the shift in importance from detritivores to microbes in warm climates would likely increase CO(2) production and decrease the generation and sequestration of recalcitrant organic particles. In view of recent estimates showing that inland waters are a significant component of the global carbon cycle, this implies consequences for global biogeochemistry and a possible positive climate feedback. © 2011 Blackwell Publishing Ltd/CNRS.

Climate warming promotes species diversity, but with greater taxonomic redundancy, in complex environments

PubMed Central

Thakur, Madhav P.; Tilman, David; Purschke, Oliver; Ciobanu, Marcel; Cowles, Jane; Isbell, Forest; Wragg, Peter D.; Eisenhauer, Nico

2017-01-01

Climate warming is predicted to alter species interactions, which could potentially lead to extinction events. However, there is an ongoing debate whether the effects of warming on biodiversity may be moderated by biodiversity itself. We tested warming effects on soil nematodes, one of the most diverse and abundant metazoans in terrestrial ecosystems, along a gradient of environmental complexity created by a gradient of plant species richness. Warming increased nematode species diversity in complex (16-species mixtures) plant communities (by ~36%) but decreased it in simple (monocultures) plant communities (by ~39%) compared to ambient temperature. Further, warming led to higher levels of taxonomic relatedness in nematode communities across all levels of plant species richness. Our results highlight both the need for maintaining species-rich plant communities to help offset detrimental warming effects and the inability of species-rich plant communities to maintain nematode taxonomic distinctness when warming occur. PMID:28740868

Thermal regimes of Rocky Mountain lakes warm with climate change

PubMed Central

Roberts, James J.

2017-01-01

Anthropogenic climate change is causing a wide range of stresses in aquatic ecosystems, primarily through warming thermal conditions. Lakes, in response to these changes, are experiencing increases in both summer temperatures and ice-free days. We used continuous records of lake surface temperature and air temperature to create statistical models of daily mean lake surface temperature to assess thermal changes in mountain lakes. These models were combined with downscaled climate projections to predict future thermal conditions for 27 high-elevation lakes in the southern Rocky Mountains. The models predict a 0.25°C·decade-1 increase in mean annual lake surface temperature through the 2080s, which is greater than warming rates of streams in this region. Most striking is that on average, ice-free days are predicted to increase by 5.9 days ·decade-1, and summer mean lake surface temperature is predicted to increase by 0.47°C·decade-1. Both could profoundly alter the length of the growing season and potentially change the structure and function of mountain lake ecosystems. These results highlight the changes expected of mountain lakes and stress the importance of incorporating climate-related adaptive strategies in the development of resource management plans. PMID:28683083

Thermal regimes of Rocky Mountain lakes warm with climate change.

PubMed

Roberts, James J; Fausch, Kurt D; Schmidt, Travis S; Walters, David M

2017-01-01

Anthropogenic climate change is causing a wide range of stresses in aquatic ecosystems, primarily through warming thermal conditions. Lakes, in response to these changes, are experiencing increases in both summer temperatures and ice-free days. We used continuous records of lake surface temperature and air temperature to create statistical models of daily mean lake surface temperature to assess thermal changes in mountain lakes. These models were combined with downscaled climate projections to predict future thermal conditions for 27 high-elevation lakes in the southern Rocky Mountains. The models predict a 0.25°C·decade-1 increase in mean annual lake surface temperature through the 2080s, which is greater than warming rates of streams in this region. Most striking is that on average, ice-free days are predicted to increase by 5.9 days ·decade-1, and summer mean lake surface temperature is predicted to increase by 0.47°C·decade-1. Both could profoundly alter the length of the growing season and potentially change the structure and function of mountain lake ecosystems. These results highlight the changes expected of mountain lakes and stress the importance of incorporating climate-related adaptive strategies in the development of resource management plans.

Thermal regimes of Rocky Mountain lakes warm with climate change

USGS Publications Warehouse

Roberts, James J.; Fausch, Kurt D.; Schmidt, Travis S.; Walters, David M.

2017-01-01

Anthropogenic climate change is causing a wide range of stresses in aquatic ecosystems, primarily through warming thermal conditions. Lakes, in response to these changes, are experiencing increases in both summer temperatures and ice-free days. We used continuous records of lake surface temperature and air temperature to create statistical models of daily mean lake surface temperature to assess thermal changes in mountain lakes. These models were combined with downscaled climate projections to predict future thermal conditions for 27 high-elevation lakes in the southern Rocky Mountains. The models predict a 0.25°C·decade-1increase in mean annual lake surface temperature through the 2080s, which is greater than warming rates of streams in this region. Most striking is that on average, ice-free days are predicted to increase by 5.9 days ·decade-1, and summer mean lake surface temperature is predicted to increase by 0.47°C·decade-1. Both could profoundly alter the length of the growing season and potentially change the structure and function of mountain lake ecosystems. These results highlight the changes expected of mountain lakes and stress the importance of incorporating climate-related adaptive strategies in the development of resource management plans.

Ocean Drilling Program Records of the Last Five Million Years: A View of the Ocean and Climate System During a Warm Period and a Major Climate Transition

NASA Astrophysics Data System (ADS)

Ravelo, A. C.

2003-12-01

The warm Pliocene (4.7 to 3.0 Ma), the most recent period in Earth's history when global equilibrium climate was warmer than today, provides the opportunity to understand what role the components of the climate system that have a long timescale of response (cryosphere and ocean) play in determining globally warm conditions, and in forcing the major global climate cooling after 3.0 Ma. Because sediments of this age are well preserved in many locations in the world's oceans, we can potentially study this warm period in detail. One major accomplishment of the Ocean Drilling Program is the recovery of long continuous sediment sequences from all ocean basins that span the last 5.0 Ma. Dozens of paleoceanographers have generated climate records from these sediments. I will present a synthesis of these data to provide a global picture of the Pliocene warm period, the transition to the cold Pleistocene period, and changes in climate sensitivity related to this transition. In the Pliocene warm period, tropical sea surface temperature (SST) and global climate patterns suggest average conditions that resemble modern El Ni¤os, and deep ocean reconstructions indicate enhanced thermohaline overturning and reduced density and nutrient stratification. The data indicate that the warm conditions were not related to tectonic changes in ocean basin shape compared to today, rather they reflect the long term adjustment of the climate system to stronger than modern radiative forcing. The warm Pliocene to cold Pleistocene transition provides an opportunity to study the feedbacks of various components of the climate system. The marked onset of significant Northern hemisphere glaciation (NHG) at 2.75 Ma occurred in concert with a reduction in deep ocean ventilation, but cooling in subtropical and tropical regions was more gradual until Walker circulation was established in a major step at 2.0 Ma. Thus, regional high latitude ice albedo feedbacks, rather than low latitude processes, must

Recent climate warming drives ecological change in a remote high-Arctic lake.

PubMed

Woelders, Lineke; Lenaerts, Jan T M; Hagemans, Kimberley; Akkerman, Keechy; van Hoof, Thomas B; Hoek, Wim Z

2018-05-01

The high Arctic is the fastest warming region on Earth, evidenced by extreme near-surface temperature increase in non-summer seasons, recent rapid sea ice decline and permafrost melting since the early 1990's. Understanding the impact of climate change on the sensitive Arctic ecosystem to climate change has so far been hampered by the lack of time-constrained, high-resolution records and by implicit climate data analyses. Here, we show evidence of sharp growth in freshwater green algae as well as distinct diatom assemblage changes since ~1995, retrieved from a high-Arctic (80 °N) lake sediment record on Barentsøya (Svalbard). The proxy record approaches an annual to biennial resolution. Combining remote sensing and in-situ climate data, we show that this ecological change is concurrent with, and is likely driven by, the atmospheric warming and a sharp decrease in the length of the sea ice covered period in the region, and throughout the Arctic. Moreover, this research demonstrates the value of palaeoclimate records in pristine environments for supporting and extending instrumental records. Our results reinforce and extend observations from other sites that the high Arctic has already undergone rapid ecological changes in response to on-going climate change, and will continue to do so in the future.

Statistical structure of intrinsic climate variability under global warming

NASA Astrophysics Data System (ADS)

Zhu, Xiuhua; Bye, John; Fraedrich, Klaus

2017-04-01

Climate variability is often studied in terms of fluctuations with respect to the mean state, whereas the dependence between the mean and variability is rarely discussed. We propose a new climate metric to measure the relationship between means and standard deviations of annual surface temperature computed over non-overlapping 100-year segments. This metric is analyzed based on equilibrium simulations of the Max Planck Institute-Earth System Model (MPI-ESM): the last millennium climate (800-1799), the future climate projection following the A1B scenario (2100-2199), and the 3100-year unforced control simulation. A linear relationship is globally observed in the control simulation and thus termed intrinsic climate variability, which is most pronounced in the tropical region with negative regression slopes over the Pacific warm pool and positive slopes in the eastern tropical Pacific. It relates to asymmetric changes in temperature extremes and associates fluctuating climate means with increase or decrease in intensity and occurrence of both El Niño and La Niña events. In the future scenario period, the linear regression slopes largely retain their spatial structure with appreciable changes in intensity and geographical locations. Since intrinsic climate variability describes the internal rhythm of the climate system, it may serve as guidance for interpreting climate variability and climate change signals in the past and the future.

Climate-induced warming imposes a threat to north European spring ecosystems.

PubMed

Jyväsjärvi, Jussi; Marttila, Hannu; Rossi, Pekka M; Ala-Aho, Pertti; Olofsson, Bo; Nisell, Jakob; Backman, Birgitta; Ilmonen, Jari; Virtanen, Risto; Paasivirta, Lauri; Britschgi, Ritva; Kløve, Bjørn; Muotka, Timo

2015-12-01

Interest in climate change effects on groundwater has increased dramatically during the last decade. The mechanisms of climate-related groundwater depletion have been thoroughly reviewed, but the influence of global warming on groundwater-dependent ecosystems (GDEs) remains poorly known. Here we report long-term water temperature trends in 66 northern European cold-water springs. A vast majority of the springs (82%) exhibited a significant increase in water temperature during 1968-2012. Mean spring water temperatures were closely related to regional air temperature and global radiative forcing of the corresponding year. Based on three alternative climate scenarios representing low (RCP2.6), intermediate (RCP6) and high-emission scenarios (RCP8.5), we estimate that increase in mean spring water temperature in the region is likely to range from 0.67 °C (RCP2.6) to 5.94 °C (RCP8.5) by 2086. According to the worst-case scenario, water temperature of these originally cold-water ecosystems (regional mean in the late 1970s: 4.7 °C) may exceed 12 °C by the end of this century. We used bryophyte and macroinvertebrate species data from Finnish springs and spring-fed streams to assess ecological impacts of the predicted warming. An increase in spring water temperature by several degrees will likely have substantial biodiversity impacts, causing regional extinction of native, cold-stenothermal spring specialists, whereas species diversity of headwater generalists is likely to increase. Even a slight (by 1 °C) increase in water temperature may eliminate endemic spring species, thus altering bryophyte and macroinvertebrate assemblages of spring-fed streams. Climate change-induced warming of northern regions may thus alter species composition of the spring biota and cause regional homogenization of biodiversity in headwater ecosystems. © 2015 John Wiley & Sons Ltd.

Sensitivity of the boreal forest-mire ecotone CO2, CH4, and N2O global warming potential to rainy and dry weather

NASA Astrophysics Data System (ADS)

Ťupek, Boris; Minkkinen, Kari; Vesala, Timo; Nikinmaa, Eero

2015-04-01

In a mosaic of well drained forests and poorly drained mires of boreal landscape the weather events such as drought and rainy control greenhouse gas dynamics and ecosystem global warming potential (GWP). In forest-mire ecotone especially in ecosystems where CO2 sink is nearly balanced with CO2 source, it's fairly unknown whether the net warming effect of emissions of gases with strong radiative forcing (CH4 and N2O) could offset the net cooling effect of CO2 sequestration. We compared the net ecosystem CO2 exchange (NEE) estimated from the carbon sequestrations of forest stands and forest floor CO2 fluxes against CH4 and N2O fluxes of nine forest/mire site types along the soil moisture gradient in Finland. The ground water of nine sites changed between 10 m in upland forests and 0.1 m in mires, and weather during three years ranged between exceptionally wet and dry for the local climate. The NEE of upland forests was typically a sink of CO2, regardless the weather. Though, xeric pine forest was estimated to be a source of CO2 during wet and intermediate year and became a weak sink only in dry year. The NEE of forest-mire transitions ranged between a sink in dry year, while increased stand carbon sequestration could offset the reduced forest floor CO2 emission, and a source in wet year. The NEE of two sparsely forested mires strongly differed. The lawn type mire was balanced around zero and the hummock type mire was relatively strong NEE sink, regardless the weather. Generally, nearly zero N2O emission could not offset the cooling effect of net CH4 sink and net CO2 sink of upland forest and forest-mire transitions. However in sparsely forested mires, with N2O emission also nearly zero, the CH4 emission during wet and intermediate year played important role in turning the net cooling effect of NEE into a net warming. When evaluating GWP of boreal landscapes, undisturbed forest-mire transitions should be regarded as net cooling ecosystems instead of hotspots of net

A westward extension of the warm pool leads to a westward extension of the Walker circulation, drying eastern Africa

USGS Publications Warehouse

Williams, A. Park; Funk, Christopher C.

2011-01-01

Observations and simulations link anthropogenic greenhouse and aerosol emissions with rapidly increasing Indian Ocean sea surface temperatures (SSTs). Over the past 60 years, the Indian Ocean warmed two to three times faster than the central tropical Pacific, extending the tropical warm pool to the west by ~40° longitude (>4,000 km). This propensity toward rapid warming in the Indian Ocean has been the dominant mode of interannual variability among SSTs throughout the tropical Indian and Pacific Oceans (55°E–140°W) since at least 1948, explaining more variance than anomalies associated with the El Niño-Southern Oscillation (ENSO). In the atmosphere, the primary mode of variability has been a corresponding trend toward greatly increased convection and precipitation over the tropical Indian Ocean. The temperature and rainfall increases in this region have produced a westward extension of the western, ascending branch of the atmospheric Walker circulation. Diabatic heating due to increased mid-tropospheric water vapor condensation elicits a westward atmospheric response that sends an easterly flow of dry air aloft toward eastern Africa. In recent decades (1980–2009), this response has suppressed convection over tropical eastern Africa, decreasing precipitation during the ‘long-rains’ season of March–June. This trend toward drought contrasts with projections of increased rainfall in eastern Africa and more ‘El Niño-like’ conditions globally by the Intergovernmental Panel on Climate Change. Increased Indian Ocean SSTs appear likely to continue to strongly modulate the Warm Pool circulation, reducing precipitation in eastern Africa, regardless of whether the projected trend in ENSO is realized. These results have important food security implications, informing agricultural development, environmental conservation, and water resource planning.

Climate warming and humans played different roles in triggering Late Quaternary extinctions in east and west Eurasia

PubMed Central

Wan, Xinru

2017-01-01

Climate change and humans are proposed as the two key drivers of total extinction of many large mammals in the Late Pleistocene and Early Holocene, but disentangling their relative roles remains challenging owing to a lack of quantitative evaluation of human impact and climate-driven distribution changes on the extinctions of these large mammals in a continuous temporal–spatial dimension. Here, our analyses showed that temperature change had significant effects on mammoth (genus Mammuthus), rhinoceros (Rhinocerotidae), horse (Equidae) and deer (Cervidae). Rapid global warming was the predominant factor driving the total extinction of mammoths and rhinos in frigid zones from the Late Pleistocene and Early Holocene. Humans showed significant, negative effects on extirpations of the four mammalian taxa, and were the predominant factor causing the extinction or major extirpations of rhinos and horses. Deer survived both rapid climate warming and extensive human impacts. Our study indicates that both the current rates of warming and range shifts of species are much faster than those from the Late Pleistocene to Holocene. Our results provide new insight into the extinction of Late Quaternary megafauna by demonstrating taxon-, period- and region-specific differences in extinction drivers of climate change and human disturbances, and some implications about the extinction risk of animals by recent and ongoing climate warming. PMID:28330916

The ice-core record - Climate sensitivity and future greenhouse warming

NASA Technical Reports Server (NTRS)

Lorius, C.; Raynaud, D.; Jouzel, J.; Hansen, J.; Le Treut, H.

1990-01-01

The prediction of future greenhouse-gas-warming depends critically on the sensitivity of earth's climate to increasing atmospheric concentrations of these gases. Data from cores drilled in polar ice sheets show a remarkable correlation between past glacial-interglacial temperature changes and the inferred atmospheric concentration of gases such as carbon dioxide and methane. These and other palaeoclimate data are used to assess the role of greenhouse gases in explaining past global climate change, and the validity of models predicting the effect of increasing concentrations of such gases in the atmosphere.

Insects Extend the Consequences of a Warm, Dry Summer for Tree Growth in the Subsequent Summer near the Arctic Treeline in Alaska

NASA Astrophysics Data System (ADS)

Sullivan, P.; Sveinbjornsson, B.

2008-12-01

Treeline positions have important implications for surface energy budgets and carbon cycling in high latitude environments. Warming temperatures during the 20th century have been associated with both positive and negative growth trends in treeline white spruce. It has been suggested that negative growth trends may reflect the increasing importance of drought stress as a constraint on tree growth, although direct observations of water stress near the treeline are lacking. We set out to develop a more mechanistic understanding of environmental controls on gas exchange physiology and growth of white spruce near the Arctic treeline in Alaska. Our three-year study was carried out on a riverside terrace along the Agashashok River in Noatak National Preserve. The terrace is capped with a layer of sand/silt that grades from 10 cm depth at the upstream end to 45 cm depth at the downstream end. White spruce of similar size occur along the gradient at similar density, providing an opportunity to examine the role of parent material depth as a control on tree physiology and growth. Air temperatures during the 2006 growing season were near normal, there was no evidence of water stress and white spruce branch extension growth was near the long-term average. The 2007 growing season was exceptionally warm and dry. Stomatal closure was observed during mid-July throughout most of the diurnal cycle in trees growing on less than 30 cm of parent material. The warm, dry conditions and water-stress in the trees may have precipitated a major insect outbreak, which affected nearly all mature trees in the landscape. Branch extension growth in 2007 was reduced to 70 percent of that observed during the 2005 and 2006 growing seasons. Air temperatures during the 2008 growing season returned to near normal. There was no evidence of water stress, but the insect outbreak persisted and branch extension growth did not recover, remaining similar to that observed in 2007. Results of our study highlight

Climatic influence on anthrax suitability in warming northern latitudes.

PubMed

Walsh, Michael G; de Smalen, Allard W; Mor, Siobhan M

2018-06-18

Climate change is impacting ecosystem structure and function, with potentially drastic downstream effects on human and animal health. Emerging zoonotic diseases are expected to be particularly vulnerable to climate and biodiversity disturbance. Anthrax is an archetypal zoonosis that manifests its most significant burden on vulnerable pastoralist communities. The current study sought to investigate the influence of temperature increases on geographic anthrax suitability in the temperate, boreal, and arctic North, where observed climate impact has been rapid. This study also explored the influence of climate relative to more traditional factors, such as livestock distribution, ungulate biodiversity, and soil-water balance, in demarcating risk. Machine learning was used to model anthrax suitability in northern latitudes. The model identified climate, livestock density and wild ungulate species richness as the most influential features in predicting suitability. These findings highlight the significance of warming temperatures for anthrax ecology in northern latitudes, and suggest potential mitigating effects of interventions targeting megafauna biodiversity conservation in grassland ecosystems, and animal health promotion among small to midsize livestock herds.

[CO2-exchange in tundra ecosystems of Vaygach Island during the unusually warm and dry vegetation season].

PubMed

Zamolodchikov, D G

2015-01-01

In summer of 2013, field studies of CO2-exchange in tundra ecosystems of Vaygach Island have been conducted using the chamber method. The models are developed that establish relationships between CO2 fluxes and key ecological factors such as temperature, photosynthetic active radiation, leaf mass of vascular plants, and depth of thawing. According to the model estimates, in 2013 vegetation season tundra ecosystems of Vaygach Island have been appearing to be a CO2 source to the atmosphere (31.9 ± 17.1 g C m(-2) season(-1)) with gross primary production equal to 136.6 ± 18.9 g C m(-2) season(-1) and ecosystem respiration of 168.5 ± ± 18.4 g C m(-2) season(-1). Emission of CO2 from the soil surface (soil respiration) has been equal, on the average, to 67.3% of the ecosystem respiration. The reason behind carbon losses by tundra ecosystems seems to be unusually warm and dry weather conditions in 2013 summer. The air temperature during summer months has been twice as high as the climatic norm for 1961-1990. Last decades, researches in the circumpolar Arctic revealed a growing trend to the carbon sink from the atmosphere to tundra ecosystems. This trend can be interrupted by unusually warm weather situations becoming more frequent and of larger scale.

Climatic warming strengthens a positive feedback between alpine shrubs and fire.

PubMed

Camac, James S; Williams, Richard J; Wahren, Carl-Henrik; Hoffmann, Ary A; Vesk, Peter A

2017-08-01

Climate change is expected to increase fire activity and woody plant encroachment in arctic and alpine landscapes. However, the extent to which these increases interact to affect the structure, function and composition of alpine ecosystems is largely unknown. Here we use field surveys and experimental manipulations to examine how warming and fire affect recruitment, seedling growth and seedling survival in four dominant Australian alpine shrubs. We found that fire increased establishment of shrub seedlings by as much as 33-fold. Experimental warming also doubled growth rates of tall shrub seedlings and could potentially increase their survival. By contrast, warming had no effect on shrub recruitment, postfire tussock regeneration, or how tussock grass affected shrub seedling growth and survival. These findings indicate that warming, coupled with more frequent or severe fires, will likely result in an increase in the cover and abundance of evergreen shrubs. Given that shrubs are one of the most flammable components in alpine and tundra environments, warming is likely to strengthen an existing feedback between woody species abundance and fire in these ecosystems. © 2017 John Wiley & Sons Ltd.

Study of landscape change under forest harvesting and climate warming-induced fire disturbance

Treesearch

S. He Hong; David J. Mladenoff; Eric J. Gustafson

2002-01-01

We examined tree species responses under forest harvesting and an increased fire disturbance scenario due to climate warming in northern Wisconsin where northern hardwood and boreal forests are currently predominant. Individual species response at the ecosystem scale was simulated with a gap model, which integrates soil, climate and species data, stratified by...

Results from the BRACE 1.5 study: Climate change impacts of 1.5 C and 2 C warming

NASA Astrophysics Data System (ADS)

O'Neill, B. C.; Anderson, B.; Monaghan, A. J.; Ren, X.; Sanderson, B.; Tebaldi, C.

2017-12-01

In 2015, 195 countries negotiated the Paris Agreement on climate change, which set long-term goals of limiting global mean warming to well below 2 C and possibly 1.5 C. This event stimulated substantial scientific interest in climate outcomes and impacts on society associated with those levels of warming. Recently, the first set of global climate model simulations explicitly designed to meet those targets were undertaken with the Community Earth System Model (CESM) for use by the research community (Sanderson et al, accepted). The BRACE 1.5 project models societal impacts from these climate outcomes, combined with assumptions about future socioeconomic conditions according to the Shared Socioeconomic Pathways. These analyses build on a recently completed study of the Benefits of Reduced Anthropogenic Climate changE (BRACE), published as a set of 20 papers in Climatic Change, which examined the difference in impacts between two higher scenarios resulting in about 2.5 C and 3.7 C warming by late this century. BRACE 1.5 consists of a set of six papers to be submitted to a special collection in Environmental Research Letters that takes a similar approach but focuses on impacts at 1.5 and 2 C warming. We ask whether impacts differ substantially between the two climate scenarios, accounting for uncertainty in climate outcomes through the use of initial condition ensembles of CESM simulations, and in societal conditions by using alternative SSP-based development pathways. Impact assessment focuses on the health and agricultural sectors; modeling approaches include the use of a global mutli-region CGE model for economic analysis, both a process-based and an empirical crop model, a model of spatial population change, a model of climatic suitability for the aedes aegypti mosquito, and an epidemiological model of heat-related mortality. A methodological analysis also evaluates the use of climate model emulation techniques for providing climate information sufficient to

An overview of dry-wet climate variability among monsoon-westerly regions and the monsoon northernmost marginal active zone in China

NASA Astrophysics Data System (ADS)

Qian, Weihong; Ding, Ting; Hu, Haoran; Lin, Xiang; Qin, Aimin

2009-07-01

Climate in mainland China can be divided into the monsoon region in the southeast and the westerly region in the northwest as well as the intercross zone, i.e., the monsoon northernmost marginal active zone that is oriented from Southwest China to the upper Yellow River, North China, and Northeast China. In the three regions, dry-wet climate changes are directly linked to the interaction of the southerly monsoon flow on the east side of the Tibetan Plateau and the westerly flow on the north side of the Plateau from the inter-annual to inter-decadal timescales. Some basic features of climate variability in the three regions for the last half century and the historical hundreds of years are reviewed in this paper. In the last half century, an increasing trend of summer precipitation associated with the enhancing westerly flow is found in the westerly region from Xinjiang to northern parts of North China and Northeast China. On the other hand, an increasing trend of summer precipitation along the Yangtze River and a decreasing trend of summer precipitation along the monsoon northernmost marginal active zone are associated with the weakening monsoon flow in East Asia. Historical documents are widely distributed in the monsoon region for hundreds of years and natural climate proxies are constructed in the non-monsoon region, while two types of climate proxies can be commonly found over the monsoon northernmost marginal active zone. In the monsoon region, dry-wet variation centers are altered among North China, the lower Yangtze River, and South China from one century to another. Dry or wet anomalies are firstly observed along the monsoon northernmost marginal active zone and shifted southward or southeastward to the Yangtze River valley and South China in about a 70-year timescale. Severe drought events are experienced along the monsoon northernmost marginal active zone during the last 5 centuries. Inter-decadal dry-wet variations are depicted by natural proxies for the

Climate and tourism in the Black Forest during the warm season.

PubMed

Endler, Christina; Matzarakis, Andreas

2011-03-01

Climate, climate change and tourism all interact. Part of the public discussion about climate change focusses on the tourism sector, with direct and indirect impacts being of equally high relevance. Climate and tourism are closely linked. Thus, climate is a very decisive factor in choices both of destination and of type of journey (active holidays, wellness, and city tours) in the tourism sector. However, whether choices about destinations or types of trip will alter with climate change is difficult to predict. Future climates can be simulated and projected, and the tendencies of climate parameters can be estimated using global and regional climate models. In this paper, the focus is on climate change in the mountainous regions of southwest Germany - the Black Forest. The Black Forest is one of the low mountain ranges where both winter and summer tourism are vulnerable to climate change due to its southern location; the strongest climatic changes are expected in areas covering the south and southwest of Germany. Moreover, as the choice of destination is highly dependent on good weather, a climatic assessment for tourism is essential. Thus, the aim of this study was to estimate climatic changes in mountainous regions during summer, especially for tourism and recreation. The assessment method was based on human-biometeorology as well as tourism-climatologic approaches. Regional climate simulations based on the regional climate model REMO were used for tourism-related climatic analyses. Emission scenarios A1B and B1 were considered for the time period 2021 to 2050, compared to the 30-year base period of 1971-2000, particularly for the warm period of the year, defined here as the months of March-November. In this study, we quantified the frequency, but not the means, of climate parameters. The study results show that global and regional warming is reflected in an increase in annual mean air temperature, especially in autumn. Changes in the spring show a slight negative

Modeling Multi-Reservoir Hydropower Systems in the Sierra Nevada with Environmental Requirements and Climate Warming

NASA Astrophysics Data System (ADS)

Rheinheimer, David Emmanuel

Hydropower systems and other river regulation often harm instream ecosystems, partly by altering the natural flow and temperature regimes that ecosystems have historically depended on. These effects are compounded at regional scales. As hydropower and ecosystems are increasingly valued globally due to growing values for clean energy and native species as well as and new threats from climate warming, it is important to understand how climate warming might affect these systems, to identify tradeoffs between different water uses for different climate conditions, and to identify promising water management solutions. This research uses traditional simulation and optimization to explore these issues in California's upper west slope Sierra Nevada mountains. The Sierra Nevada provides most of the water for California's vast water supply system, supporting high-elevation hydropower generation, ecosystems, recreation, and some local municipal and agricultural water supply along the way. However, regional climate warming is expected to reduce snowmelt and shift runoff to earlier in the year, affecting all water uses. This dissertation begins by reviewing important literature related to the broader motivations of this study, including river regulation, freshwater conservation, and climate change. It then describes three substantial studies. First, a weekly time step water resources management model spanning the Feather River watershed in the north to the Kern River watershed in the south is developed. The model, which uses the Water Evaluation And Planning System (WEAP), includes reservoirs, run-of-river hydropower, variable head hydropower, water supply demand, and instream flow requirements. The model is applied with a runoff dataset that considers regional air temperature increases of 0, 2, 4 and 6 °C to represent historical, near-term, mid-term and far-term (end-of-century) warming. Most major hydropower turbine flows are simulated well. Reservoir storage is also

Seventh Grade Students' Conceptions of Global Warming and Climate Change

ERIC Educational Resources Information Center

Shepardson, Daniel P.; Niyogi, Dev; Choi, Soyoung; Charusombat, Umarporn

2009-01-01

The purpose of this study was to investigate seventh grade students' conceptions of global warming and climate change. The study was descriptive in nature and involved the collection of qualitative data from 91 seventh grade students from three different schools in the Midwest, USA. An open response and draw and explain assessment instrument was…

Warm-water coral reefs and climate change

NASA Astrophysics Data System (ADS)

Spalding, Mark D.; Brown, Barbara E.

2015-11-01

Coral reefs are highly dynamic ecosystems that are regularly exposed to natural perturbations. Human activities have increased the range, intensity, and frequency of disturbance to reefs. Threats such as overfishing and pollution are being compounded by climate change, notably warming and ocean acidification. Elevated temperatures are driving increasingly frequent bleaching events that can lead to the loss of both coral cover and reef structural complexity. There remains considerable variability in the distribution of threats and in the ability of reefs to survive or recover from such disturbances. Without significant emissions reductions, however, the future of coral reefs is increasingly bleak.

Areas of potential suitability and survival of Dendroctonus valens in China under extreme climate warming scenario.

PubMed

He, S Y; Ge, X Z; Wang, T; Wen, J B; Zong, S X

2015-08-01

The areas in China with climates suitable for the potential distribution of the pest species red turpentine beetle (RTB) Dendroctonus valens LeConte (Coleoptera: Scolytidae) were predicted by CLIMEX based on historical climate data and future climate data with warming estimated. The model used a historical climate data set (1971-2000) and a simulated climate data set (2010-2039) provided by the Tyndall Centre for Climate Change (TYN SC 2.0). Based on the historical climate data, a wide area was available in China with a suitable climate for the beetle in which every province might contain suitable habitats for this pest, particularly all of the southern provinces. The northern limit of the distribution of the beetle was predicted to reach Yakeshi and Elunchun in Inner Mongolia, and the western boundary would reach to Keerkezi in Xinjiang Province. Based on a global-warming scenario, the area with a potential climate suited to RTB in the next 30 years (2010-2039) may extend further to the northeast. The northern limit of the distribution could reach most parts of south Heilongjiang Province, whereas the western limit would remain unchanged. Combined with the tendency for RTB to spread, the variation in suitable habitats within the scenario of extreme climate warming and the multiple geographical elements of China led us to assume that, within the next 30 years, RTB would spread towards the northeast, northwest, and central regions of China and could be a potentially serious problem for the forests of China.

The McMurdo Dry Valleys, Antarctica: Terrestrial and aquatic ecosystems responding to climatic events that enhance hydrologic transport acress the landscape

NASA Astrophysics Data System (ADS)

McKnight, D. M.; Lyons, W. B.; Fountain, A. G.; Gooseff, M. N.; Doran, P. T.; Wall, D. H.; Virginia, R. A.; Priscu, J. C.; Adams, B.; Vesbach-Takacs, C.; Barrett, J. E.; Howkins, A.

2014-12-01

The McMurdo Dry Valleys of Antarctica is comprised of alpine and terminal glaciers, large expanses of patterned ground, and permanently ice-covered lakes in the valley floors, which are linked by glacial meltwater streams that flow during the austral summer. These valleys were first explored by Robert Scott and his party in 1903. In 1968 the New Zealand Antarctic Program began a gauging network on the Onyx River, a 32 km river in Wright Valley which is the longest river in Antarctica. As part of the McMurdo Dry Valleys Long-Term Ecological research project our research group has monitored meteorological conditions, glacial mass balance, lake level and streamflow in the adjacent Taylor Valley. The extent of liquid water throughout the landscape is strongly controlled by summer climate, and the availability of liquid water in turn is a limitation to the microscopic life that is present in the diverse habitats in the valleys. We have studied the responses of soil, lake, stream and cryoconite ecosystems through a sustained cooling period that has been driven by atmospheric changes associated with the ozone hole. In the past decade, this cooling period appears to have ceased and summer conditions have become more variable. Three warm sunny summers have occurred since 2001/02. These conditions have created weeks long "flood events" in the valleys, causing wet areas to emerge in the soils, thermokarsting in some stream channels and increases in lake level. These flood events can be considered as pulse events that drive an increase in ecosystem connectivity, changing rates of biogeochemical processes and the distribution of biota. Collectively the ecosystems of the McMurdo Dry Valleys are highly responsive to dynamic climatic influences associated with the ozone hole and global warming.

Projected changes in diverse ecosystems from climate warming and biophysical drivers in northwest Alaska

Treesearch

Mark Torre Jorgenson; Bruce G. Marcot; David K. Swanson; Janet C. Jorgenson; Anthony R. DeGange

2015-01-01

Climate warming affects arctic and boreal ecosystems by interacting with numerous biophysical factors across heterogeneous landscapes. To assess potential effects of warming on diverse local-scale ecosystems (ecotypes) across northwest Alaska, we compiled data on historical areal changes over the last 25–50 years. Based on historical rates of change relative to time...

Constant diurnal temperature regime alters the impact of simulated climate warming on a tropical pseudoscorpion

NASA Astrophysics Data System (ADS)

Zeh, Jeanne A.; Bonilla, Melvin M.; Su, Eleanor J.; Padua, Michael V.; Anderson, Rachel V.; Zeh, David W.

2014-01-01

Recent theory suggests that global warming may be catastrophic for tropical ectotherms. Although most studies addressing temperature effects in ectotherms utilize constant temperatures, Jensen's inequality and thermal stress considerations predict that this approach will underestimate warming effects on species experiencing daily temperature fluctuations in nature. Here, we tested this prediction in a neotropical pseudoscorpion. Nymphs were reared in control and high-temperature treatments under a constant daily temperature regime, and results compared to a companion fluctuating-temperature study. At constant temperature, pseudoscorpions outperformed their fluctuating-temperature counterparts. Individuals were larger, developed faster, and males produced more sperm, and females more embryos. The greatest impact of temperature regime involved short-term, adult exposure, with constant temperature mitigating high-temperature effects on reproductive traits. Our findings demonstrate the importance of realistic temperature regimes in climate warming studies, and suggest that exploitation of microhabitats that dampen temperature oscillations may be critical in avoiding extinction as tropical climates warm.

Physiological constraints to climate warming in fish follow principles of plastic floors and concrete ceilings.

PubMed

Sandblom, Erik; Clark, Timothy D; Gräns, Albin; Ekström, Andreas; Brijs, Jeroen; Sundström, L Fredrik; Odelström, Anne; Adill, Anders; Aho, Teija; Jutfelt, Fredrik

2016-05-17

Understanding the resilience of aquatic ectothermic animals to climate warming has been hindered by the absence of experimental systems experiencing warming across relevant timescales (for example, decades). Here, we examine European perch (Perca fluviatilis, L.) from the Biotest enclosure, a unique coastal ecosystem that maintains natural thermal fluctuations but has been warmed by 5-10 °C by a nuclear power plant for over three decades. We show that Biotest perch grow faster and display thermally compensated resting cardiorespiratory functions compared with reference perch living at natural temperatures in adjacent waters. However, maximum cardiorespiratory capacities and heat tolerance limits exhibit limited or no thermal compensation when compared with acutely heated reference perch. We propose that while basal energy requirements and resting cardiorespiratory functions (floors) are thermally plastic, maximum capacities and upper critical heat limits (ceilings) are much less flexible and thus will limit the adaptive capacity of fishes in a warming climate.

Impact of the Medieval Climate Anomaly, Little Ice Age, and Recent Warming on Hydrology and Carbon Accumulation in the James Bay Lowland

NASA Astrophysics Data System (ADS)

Holmquist, J. R.; Booth, R. K.; MacDonald, G. M.

2013-12-01

Reconstructing late-Holocene hydroclimatic variations can be useful to understand the sensitivity of peatland soil carbon (C) to climate change (Bunbury et al., 2012). We reconstructed water table depth (WTD), using testate amoebae, for a four-core north to south transect of the James Bay Lowland and Boreal Shield of Ontario, Canada, and compared WTD to long-term apparent rate of C accumulation (LARCA). The three southern sites indicate that WTD fluctuated relative to the mean, with a wetter Medieval Climate Anomaly (MCA) and drier Little Ice Age (LIA) (Fig. 1). However, the most northern site recorded a wet LIA and dry MCA (Fig. 1). All four cores recorded drying coincident with modern warming (Fig. 1). Increased Medieval moisture detected in the three southern sites is consistent with a geographic pattern of precipitation anomalies associated with La Niña-like conditions, which cause drought in the American southwest and central plains regions coupled with increased moisture in the Pacific Northwest and north of the Great Lakes (Feng et al., 2008; Seager et al., 2008). Despite the hydroclimatic sensitivity of the region, we observed no consistent relationship between variations in WTD and LARCA from the same cores. At these particular sites, at least, C accumulation has not been sensitive to the range of climatic variability associated with the MCA, LIA and recent warming. Bunbury, J., Finkelstein, S. A., & Bollmann, J. (2012). Holocene hydro-climatic change and effects on carbon accumulation inferred from a peat bog in the Attawapiskat River watershed, Hudson Bay Lowlands, Canada. Quaternary Research: 275-284. Feng, S., Oglesby, R. J., Rowe, C. M., Loope, D. B., & Hu, Q. (2008). Atlantic and Pacific SST influences on Medieval drought in North America simulated by the Community Atmospheric Model. Journal of Geophysical Research: Atmospheres (1984-2012), 113(D11). Seager, R., Burgman, R., Kushnir, Y., Clement, A., Cook, E., Naik, N., & Miller, J. (2008). Tropical

Climate warming increases biological control agent impact on a non-target species.

PubMed

Lu, Xinmin; Siemann, Evan; He, Minyan; Wei, Hui; Shao, Xu; Ding, Jianqing

2015-01-01

Climate change may shift interactions of invasive plants, herbivorous insects and native plants, potentially affecting biological control efficacy and non-target effects on native species. Here, we show how climate warming affects impacts of a multivoltine introduced biocontrol beetle on the non-target native plant Alternanthera sessilis in China. In field surveys across a latitudinal gradient covering their full distributions, we found beetle damage on A. sessilis increased with rising temperature and plant life history changed from perennial to annual. Experiments showed that elevated temperature changed plant life history and increased insect overwintering, damage and impacts on seedling recruitment. These results suggest that warming can shift phenologies, increase non-target effect magnitude and increase non-target effect occurrence by beetle range expansion to additional areas where A. sessilis occurs. This study highlights the importance of understanding how climate change affects species interactions for future biological control of invasive species and conservation of native species. © 2014 The Authors. Ecology Letters published by John Wiley & Sons Ltd and CNRS.

Improving the effectiveness of communication about climate science: Insights from the "Global Warming's Six Americas" audience segmentation research project

NASA Astrophysics Data System (ADS)

Maibach, E.; Roser-Renouf, C.

2011-12-01

That the climate science community has not been entirely effective in sharing what it knows about climate change with the broader public - and with policy makers and organizations that should be considering climate change when making decisions - is obvious. Our research shows that a large majority of the American public trusts scientists (76%) and science-based agencies (e.g., 76% trust NOAA) as sources of information about climate change. Yet, despite the widespread agreement in the climate science community that the climate is changing as a result of human activity, only 64% of the public understand that the world's average temperature has been increasing (and only about half of them are sure), less than half (47%) understand that the warming is caused mostly by human activity, and only 39% understand that most scientists think global warming is happening (in fact, only 13% understand that the large majority of climate scientists think global warming is happening). Less obvious is what the climate science community should do to become more effective in sharing what it knows. In this paper, we will use evidence from our "Global Warming's Six Americas" audience segmentation research project to suggest ways that individual climate scientists -- and perhaps more importantly, ways in which climate science agencies and professional societies -- can enhance the effectiveness of their communication efforts. We will conclude by challenging members of the climate science community to identify and convey "simple, clear messages, repeated often, by a variety of trusted sources" - an approach to communication repeatedly shown to be effective by the public health community.

Tree water dynamics in a drying and warming world: Future tree water dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grossiord, Charlotte; Sevanto, Sanna; Borrego, Isaac

Disentangling the relative impacts of precipitation reduction and vapour pressure deficit (VPD) on plant water dynamics and determining whether acclimation may influence these patterns in the future is an important challenge. Here, we report sap flux density (FD), stomatal conductance (Gs), hydraulic conductivity (KL) and xylem anatomy in piñon pine (Pinus edulis) and juniper (Juniperus monosperma) trees subjected to five years of precipitation reduction, atmospheric warming (elevated VPD) and their combined effects. No acclimation occurred under precipitation reduction: lower Gs and FD were found for both species compared to ambient conditions. Warming reduced the sensibility of stomata to VPD formore » both species but resulted in the maintenance of Gs and FD to ambient levels only for piñon. For juniper, reduced soil moisture under warming negated benefits of stomatal adjustments and resulted in reduced FD, Gs and KL. Although reduced stomatal sensitivity to VPD also occurred under combined stresses, reductions in Gs, FD and KL took place to similar levels as under single stresses for both species. Our results show that stomatal conductance adjustments to high VPD could minimize but not entirely prevent additive effects of warming and drying on water use and carbon acquisition of trees in semi-arid regions.« less

Climate warming and humans played different roles in triggering Late Quaternary extinctions in east and west Eurasia.

PubMed

Wan, Xinru; Zhang, Zhibin

2017-03-29

Climate change and humans are proposed as the two key drivers of total extinction of many large mammals in the Late Pleistocene and Early Holocene, but disentangling their relative roles remains challenging owing to a lack of quantitative evaluation of human impact and climate-driven distribution changes on the extinctions of these large mammals in a continuous temporal-spatial dimension. Here, our analyses showed that temperature change had significant effects on mammoth (genus Mammuthus ), rhinoceros (Rhinocerotidae), horse (Equidae) and deer (Cervidae). Rapid global warming was the predominant factor driving the total extinction of mammoths and rhinos in frigid zones from the Late Pleistocene and Early Holocene. Humans showed significant, negative effects on extirpations of the four mammalian taxa, and were the predominant factor causing the extinction or major extirpations of rhinos and horses. Deer survived both rapid climate warming and extensive human impacts. Our study indicates that both the current rates of warming and range shifts of species are much faster than those from the Late Pleistocene to Holocene. Our results provide new insight into the extinction of Late Quaternary megafauna by demonstrating taxon-, period- and region-specific differences in extinction drivers of climate change and human disturbances, and some implications about the extinction risk of animals by recent and ongoing climate warming. © 2017 The Author(s).

[Impacts of climate change on food production in Gansu: A review].

PubMed

Yang, Feng-ke; He, Bao-lin; Gao, Shi-ming

2015-03-01

The climate of Gansu turned to be overall warming-drying and partly warming-wetting since 1986. In contrast to that of 1960, the average annual temperature had raised by 1.1°C with the average annual precipitation decreased by 28 mm correspondingly, which made the arid region expanded southward by 50 km in 2010. Climate warming increased the growth period effective accumulated temperature of main food grain crops and lengthened the crop growth period. It changed crop maturity, crop disposition, cropping system and generally increased the cultivatable area and planting altitude above the sea level of major crops and expanded northward the multiple cropping system, which further resulted in expansion of autumn grain crop sown area, shrink of summer grain crop sown area, and replacement of strong winter early maturing varieties by weak winter middle late maturing varieties. It benefited the crop yield by increasing the use efficiency of photo-thermal resources. Warming-wetting climate increased the climate productivity of oasis crop while warming-drying weather decreased the climate productivity of rainfed crops, which were mostly determined by the precipitation regimes and water conditions. Any advanced technique that can increase precipitation use ratio and water use efficiency as well as improve and promote soil quality and fertility should be regarded as an effective countermeasure to increase food grain production under climate change in Gsansu. So, selecting and breeding new crop varieties with the characteristics of strong resistance, weak winter, middle-late mature and high water use efficiency, establishing new planting structure and cropping system that suitable to the precipitation and temperature features of changed climate, are the development direction of food grain production in Gansu to cope with the climate change.

Impacts of climate change and climate extremes on major crops productivity in China at a global warming of 1.5 and 2.0 °C

NASA Astrophysics Data System (ADS)

Chen, Yi; Zhang, Zhao; Tao, Fulu

2018-05-01

A new temperature goal of holding the increase in global average temperature well below 2 °C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 °C above pre-industrial levels has been established in the Paris Agreement, which calls for an understanding of climate risk under 1.5 and 2.0 °C warming scenarios. Here, we evaluated the effects of climate change on growth and productivity of three major crops (i.e. maize, wheat, rice) in China during 2106-2115 in warming scenarios of 1.5 and 2.0 °C using a method of ensemble simulation with well-validated Model to capture the Crop-Weather relationship over a Large Area (MCWLA) family crop models, their 10 sets of optimal crop model parameters and 70 climate projections from four global climate models. We presented the spatial patterns of changes in crop growth duration, crop yield, impacts of heat and drought stress, as well as crop yield variability and the probability of crop yield decrease. Results showed that climate change would have major negative impacts on crop production, particularly for wheat in north China, rice in south China and maize across the major cultivation areas, due to a decrease in crop growth duration and an increase in extreme events. By contrast, with moderate increases in temperature, solar radiation, precipitation and atmospheric CO2 concentration, agricultural climate resources such as light and thermal resources could be ameliorated, which would enhance canopy photosynthesis and consequently biomass accumulations and yields. The moderate climate change would slightly worsen the maize growth environment but would result in a much more appropriate growth environment for wheat and rice. As a result, wheat, rice and maize yields would change by +3.9 (+8.6), +4.1 (+9.4) and +0.2 % (-1.7 %), respectively, in a warming scenario of 1.5 °C (2.0 °C). In general, the warming scenarios would bring more opportunities than risks for crop development and

Warming trumps CO2: future climate conditions suppress carbon fluxes in two dominant boreal tree species

NASA Astrophysics Data System (ADS)

Way, D.; Dusenge, M. E.; Madhavji, S.

2017-12-01

Increases in CO2 are expected to raise air temperatures in northern latitudes by up to 8 °C by the end of the century. Boreal forests in these regions play a large role in the global carbon cycle, and the responses of boreal tree species to climate drivers will thus have considerable impacts on the trajectory of future CO2 increases. We grew two dominant North American boreal tree species at a range of future climate conditions to assess how carbon fluxes were altered by high CO2 and warming. Black spruce (Picea mariana) and tamarack (Larix laricina) were grown from seed under either ambient (400 ppm) or elevated CO2 concentrations (750 ppm) and either ambient temperatures, moderate warming (ambient +4 °C), or extreme warming (ambient +8 °C) for six months. We measured temperature responses of net photosynthesis, maximum rates of Rubisco carboxylation (Vcmax) and electron transport (Jmax) and dark respiration to determine acclimation to the climate treatments. Overall, growth temperature had a strong effect on carbon fluxes, while there were no significant effects of growth CO2. In both species, the photosynthetic thermal optimum increased and maximum photosynthetic rates were reduced in warm-grown seedlings, but the strength of these changes varied between species. Vcmax and Jmax were also reduced in warm-grown seedlings, and this correlated with reductions in leaf N concentrations. Warming increased the activation energy for Vcmax and the thermal optimum for Jmax in both species. Respiration acclimated to elevated growth temperatures, but there were no treatment effects on the Q10 of respiration (the increase in respiration for a 10 °C increase in leaf temperature). Our results show that climate warming is likely to reduce carbon fluxes in these boreal conifers, and that photosynthetic parameters used to model photosynthesis in dynamic global vegetation models acclimate to increased temperatures, but show little response to elevated CO2.

The hydroclimatological response to global warming based on the dynamically downscaled climate change scenario

NASA Astrophysics Data System (ADS)

Im, Eun-Soon; Coppola, Erika; Giorgi, Felippo

2010-05-01

Given the discernable evidences of climate changes due to human activity, there is a growing demand for the reliable climate change scenario in response to future emission forcing. One of the most significant impacts of climate changes can be that on the hydrological process. Changes in the seasonality and increase in the low and high rainfall extremes can severely influence the water balance of river basin, with serious consequences for societies and ecosystems. In fact, recent studies have reported that East Asia including the Korean peninsula is regarded to be a highly vulnerability region under global warming, in particular for water resources. As an attempt accurately assess the impact of climate change over Korea, we performed a downscaling of the ECAHM5-MPI/OM global projection under the A1B emission scenario for the period 1971-2100 using the RegCM3 one-way double-nested system. Physically based long-term (130 years) fine-scale (20 km) climate information is appropriate for analyzing the detailed structure of the hydroclimatological response to climate change. Changes in temperature and precipitation are translated to the hydrological condition in a direct or indirect way. The change in precipitation shows a distinct seasonal variations and a complicated spatial pattern. While changes in total precipitation do not show any relevant trend, the change patterns in daily precipitation clearly show an enhancement of high intensity precipitation and a reduction of weak intensity precipitation. The increase of temperature enhances the evapotranspiration, and hence the actual water stress becomes more pronounced in the future climate. Precipitation, snow, and runoff changes show the relevant topographical modulation under global warming. This study clearly demonstrates the importance of a refined topography for improving the accuracy of the local climatology. Improved accuracy of regional climate projection could lead to an enhanced reliability of the

Energetic contribution potential of building-integrated photovoltaics on airports in warm climates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruether, Ricardo; LABSOLAR - Laboratorio de Energia Solar, UFSC - Universidade Federal de Santa Catarina, Caixa Postal 476, Florianopolis, SC 88040-900; Braun, Priscila

2009-10-15

Especially in warm climates, a considerable fraction of the electricity demand in commercial buildings is due to the intensive use of air-conditioning systems. Airport buildings in sunny and warm regions present a perfect match between energy demand and solar resource availability. Airport buildings are also typically large and horizontal, isolated and free of shading, and have a great potential for the integration of solar photovoltaic (PV) systems. In this work, we assess the potential impact in energy demand reduction at the Florianopolis International Airport in Brazil (27 S, 48 W) with the use of building-integrated photovoltaic (BIPV) systems. We analysemore » the building's hourly energy consumption and solar irradiation data, to assess the match between energy demand and potential generation, and we estimate the PV power necessary to supply both the total amount and fractions of the annual energy demand. Our results show that the integration of PV systems on airport buildings in warm climates can supply the entire electric power consumption of an airport complex, in line with the general concept of a zero-energy building (ZEB). (author)« less

Recurrent sublethal warming reduces embryonic survival, inhibits juvenile growth, and alters species distribution projections under climate change.

PubMed

Carlo, Michael A; Riddell, Eric A; Levy, Ofir; Sears, Michael W

2018-01-01

The capacity to tolerate climate change often varies across ontogeny in organisms with complex life cycles. Recently developed species distribution models incorporate traits across life stages; however, these life-cycle models primarily evaluate effects of lethal change. Here, we examine impacts of recurrent sublethal warming on development and survival in ecological projections of climate change. We reared lizard embryos in the laboratory under temperature cycles that simulated contemporary conditions and warming scenarios. We also artificially warmed natural nests to mimic laboratory treatments. In both cases, recurrent sublethal warming decreased embryonic survival and hatchling sizes. Incorporating survivorship results into a mechanistic species distribution model reduced annual survival by up to 24% compared to models that did not incorporate sublethal warming. Contrary to models without sublethal effects, our model suggests that modest increases in developmental temperatures influence species ranges due to effects on survivorship. © 2017 John Wiley & Sons Ltd/CNRS.

The role of climate change in interpreting historical variability

Treesearch

Constance I. Millar; Wallace B. Woolfenden

1999-01-01

Significant climate anomalies have characterized the last 1000 yr in the Sierra Nevada, California, USA. Two warm, dry periods of 150- and 200-yr duration occurred during AD 900-1350, which were followed by anomalously cold climates, known as the Little Ice Age, that lasted from AD 1400 to 1900. Climate in the last century has been significantly warmer. Regional biotic...

Glaciers in Equilibrium - Results from the McMurdo Dry Valleys, Antarctica

NASA Astrophysics Data System (ADS)

Fountain, A. G.; Nylen, T. H.; Doran, P. T.

2004-12-01

Since 1993 the mass balance of two glaciers in the McMurdo Dry Valleys, Antarctica (163° E 77.5° S) has been measured. The magnitude of annual mass gain or loss does not exceed 10 cm water equivalent averaged over each glacier, consistent with the local climate of a polar desert. The overall trend in mass balance shows that the glaciers are in approximate balance with the current climate and no obvious trends exist in either the winter or summer balances. These are similar to a set of mass balance measurements made in another part of the dry valleys during the 1970s (Chinn, 1985). Recent analysis of the climate of the dry valleys shows this region is cooling at a rate of 0.7° C per decade during this period since 1986, which is reflected in the overall lowering of lake levels, decreased primary productivity of the lakes, and declining number of invertebrates (Doran et al., 2002). Although an unusually warm period occurred in the summer of 2001-2002, annual temperatures continue to cool. This region seems to be isolated from the warming elsewhere in Antarctica and the cooling in this part of the Ross Sea region may be due to El Nino forcing (Bertler et al, 2004). The sluggish behavior of the glaciers results from a low mass exchange and an apparent climatic buffering, which supports evidence from the geologic record that these glaciers have not advanced more than a few hundred meters over the past 3 million years (Hall et al., 1993). Many of the glaciers, however, are advancing which probably results from a slow time-scale response from warming conditions in the past millennium.

Climate warming and the carbon cycle in the permafrost zone of the former Soviet Union

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kolchugina, T.P.; Vinson, T.S.

1993-01-01

The continuous permafrost zone of the former Soviet Union occupies 5% of the land surface area of the earth and stores a significant amount of carbon. Climate warming could disrupt the balance between carbon (C) accumulation and decomposition processes within the permafrost zone. Increased temperatures may accelerate the rate of organic matter decomposition. At the same time, the productivity of vegetation may increase in response to warming. To assess the future carbon cycle within the permafrost zone under a climate-warming scenario, it is necessary to quantify present carbon pools and fluxes. The present carbon cycle was assessed on the basismore » of an ecosystem/ecoregion approach. Under the present climate, the phytomass carbon pool was estimated at 17.0 Giga tons. The mortmass (coarse woody debris) carbon pool was estimated at 16.1 Giga tons. The soil carbon pool, including peatlands, was 139.4 Giga tons. The present rate of carbon turnover was 1.6 Giga tons/yr. (Copyright (c) 1993 by John Wiley and Sons, Ltd.)« less

A westward extension of the warm pool leads to a westward extension of the Walker circulation, drying eastern Africa

USGS Publications Warehouse

Funk, Christopher C.; Williams, A. Park

2011-01-01

Observations and simulations link anthropogenic greenhouse and aerosol emissions with rapidly increasing Indian Ocean sea surface temperatures (SSTs). Over the past 60 years, the Indian Ocean warmed two to three times faster than the central tropical Pacific, extending the tropical warm pool to the west by ~40° longitude (>4,000 km). This propensity toward rapid warming in the Indian Ocean has been the dominant mode of interannual variability among SSTs throughout the tropical Indian and Pacific Oceans (55°E–140°W) since at least 1948, explaining more variance than anomalies associated with the El Niño-Southern Oscillation (ENSO). In the atmosphere, the primary mode of variability has been a corresponding trend toward greatly increased convection and precipitation over the tropical Indian Ocean. The temperature and rainfall increases in this region have produced a westward extension of the western, ascending branch of the atmospheric Walker circulation. Diabatic heating due to increased mid-tropospheric water vapor condensation elicits a westward atmospheric response that sends an easterly flow of dry air aloft toward eastern Africa. In recent decades (1980–2009), this response has suppressed convection over tropical eastern Africa, decreasing precipitation during the ‘long-rains’ season of March–June. This trend toward drought contrasts with projections of increased rainfall in eastern Africa and more ‘El Niño-like’ conditions globally by the Intergovernmental Panel on Climate Change. Increased Indian Ocean SSTs appear likely to continue to strongly modulate the Warm Pool circulation, reducing precipitation in eastern Africa, regardless of whether the projected trend in ENSO is realized. These results have important food security implications, informing agricultural development, environmental conservation, and water resource planning.

Extrapolating carbon dynamics of tropical dry forests into future climates: improving simulation models with empirical observations

NASA Astrophysics Data System (ADS)

Medvigy, David; Waring, Bonnie; Vargas, German; Xu, Xiangtao; Smith, Christina; Becknell, Justin; Trierweiler, Annette; Brodribb, Timothy; Powers, Jennifer

2017-04-01

Tropical dry forests occur in areas with warm temperatures and a pronounced dry season with little to no rainfall that lasts 3 to 7 months. The potential area covered by this biome is vast: globally, 47% of all forest occurs in tropical and subtropical latitudes, and of all tropical forests approximately 42% are classified as dry forests. Throughout the last several centuries, the area covered by tropical dry forests has been dramatically reduced through conversion to grazing and croplands, and they are now considered the most threatened tropical biome. However, in many regions, tropical dry forests are now growing back. There is growing concern that this recovery process will be strongly impacted by climate variability and change. Observations show that climate is changing in the seasonal tropics, and climate models forecast that neotropical dry forests will receive significantly less rainfall in the 21st century than in the 20th century. Rates of nitrogen deposition are also changing rapidly in this sector, and the fertility of some soils may still be recovering from past land use. We are engaged in several efforts to understand how water and nutrients limit the productivity of these forests, including manipulative experiments, modeling, and investigation of responses to natural climate variability. In 2015, at a well-characterized site in Guanacaste, Costa Rica, we established a full-factorial fertilization experiment with N and P in diverse mature forest stands. Initial responses highlight stronger ecosystem sensitivity to P addition than to N addition. Intriguingly, pre-experiment numerical simulations with a mechanistic ecosystem model had indicated the reverse. Work is ongoing to use field observations to better represent critical processes in the model, and ultimately to improve the model's sensitivity to nutrients and water. In addition, in 2016, we established a full factorial nutrient addition and drought experiment in plantations. Thus far, soil

West African Monsoon dynamics in idealized simulations: the competitive roles of SST warming and CO2

NASA Astrophysics Data System (ADS)

Gaetani, Marco; Flamant, Cyrille; Hourdin, Frederic; Bastin, Sophie; Braconnot, Pascale; Bony, Sandrine

2015-04-01

The West African Monsoon (WAM) is affected by large climate variability at different timescales, from interannual to multidecadal, with strong environmental and socio-economic impacts associated to climate-related rainfall variability, especially in the Sahelian belt. State-of-the-art coupled climate models still show poor ability in correctly simulating the WAM past variability and also a large spread is observed in future climate projections. In this work, the July-to-September (JAS) WAM variability in the period 1979-2008 is studied in AMIP-like simulations (SST-forced) from CMIP5. The individual roles of global SST warming and CO2 concentration increasing are investigated through idealized experiments simulating a 4K warmer SST and a 4x CO2 concentration, respectively. Results show a dry response in Sahel to SST warming, with dryer conditions over western Sahel. On the contrary, wet conditions are observed when CO2 is increased, with the strongest response over central-eastern Sahel. The precipitation changes are associated to modifications in the regional atmospheric circulation: dry (wet) conditions are associated with reduced (increased) convergence in the lower troposphere, a southward (northward) shift of the African Easterly Jet, and a weaker (stronger) Tropical Easterly Jet. The co-variability between global SST and WAM precipitation is also investigated, highlighting a reorganization of the main co-variability modes. Namely, in the 4xCO2 simulation the influence of Tropical Pacific is dominant, while it is reduced in the 4K simulation, which also shows an increased coupling with the eastern Pacific and the Indian Ocean. The above results suggest a competitive action of SST warming and CO2 increasing on the WAM climate variability, with opposite effects on precipitation. The combination of the observed positive and negative response in precipitation, with wet conditions in central-eastern Sahel and dry conditions in western Sahel, is consistent with the

Paris Agreement climate proposals need a boost to keep warming well below 2 °C.

PubMed

Rogelj, Joeri; den Elzen, Michel; Höhne, Niklas; Fransen, Taryn; Fekete, Hanna; Winkler, Harald; Schaeffer, Roberto; Sha, Fu; Riahi, Keywan; Meinshausen, Malte

2016-06-30

The Paris climate agreement aims at holding global warming to well below 2 degrees Celsius and to "pursue efforts" to limit it to 1.5 degrees Celsius. To accomplish this, countries have submitted Intended Nationally Determined Contributions (INDCs) outlining their post-2020 climate action. Here we assess the effect of current INDCs on reducing aggregate greenhouse gas emissions, its implications for achieving the temperature objective of the Paris climate agreement, and potential options for overachievement. The INDCs collectively lower greenhouse gas emissions compared to where current policies stand, but still imply a median warming of 2.6-3.1 degrees Celsius by 2100. More can be achieved, because the agreement stipulates that targets for reducing greenhouse gas emissions are strengthened over time, both in ambition and scope. Substantial enhancement or over-delivery on current INDCs by additional national, sub-national and non-state actions is required to maintain a reasonable chance of meeting the target of keeping warming well below 2 degrees Celsius.

500-year climate cycles stacking of recent centennial warming documented in an East Asian pollen record

PubMed Central

Xu, Deke; Lu, Houyuan; Chu, Guoqiang; Wu, Naiqin; Shen, Caiming; Wang, Can; Mao, Limi

2014-01-01

Here we presented a high-resolution 5350-year pollen record from a maar annually laminated lake in East Asia (EA). Pollen record reflected the dynamics of vertical vegetation zones and temperature change. Spectral analysis on pollen percentages/concentrations of Pinus and Quercus, and a temperature proxy, revealed ~500-year quasi-periodic cold-warm fluctuations during the past 5350 years. This ~500-year cyclic climate change occurred in EA during the mid-late Holocene and even the last 150 years dominated by anthropogenic forcing. It was almost in phase with a ~500-year periodic change in solar activity and Greenland temperature change, suggesting that ~500-year small variations in solar output played a prominent role in the mid-late Holocene climate dynamics in EA, linked to high latitude climate system. Its last warm phase might terminate in the next several decades to enter another ~250-year cool phase, and thus this future centennial cyclic temperature minimum could partially slow down man-made global warming. PMID:24402348

Climate Warming Can Increase Soil Carbon Fluxes Without Decreasing Soil Carbon Stocks in Boreal Forests

NASA Astrophysics Data System (ADS)

Ziegler, S. E.; Benner, R. H.; Billings, S. A.; Edwards, K. A.; Philben, M. J.; Zhu, X.; Laganiere, J.

2016-12-01

Ecosystem C fluxes respond positively to climate warming, however, the net impact of changing C fluxes on soil organic carbon (SOC) stocks over decadal scales remains unclear. Manipulative studies and global-scale observations have informed much of the existing knowledge of SOC responses to climate, providing insights on relatively short (e.g. days to years) and long (centuries to millennia) time scales, respectively. Natural climate gradient studies capture integrated ecosystem responses to climate on decadal time scales. Here we report the soil C reservoirs, fluxes into and out of those reservoirs, and the chemical composition of inputs and soil organic matter pools along a mesic boreal forest climate transect. The sites studied consist of similar forest composition, successional stage, and soil moisture but differ by 5.2°C mean annual temperature. Carbon fluxes through these boreal forest soils were greatest in the lowest latitude regions and indicate that enhanced C inputs can offset soil C losses with warming in these forests. Respiration rates increased by 55% and the flux of dissolved organic carbon from the organic to mineral soil horizons tripled across this climate gradient. The 2-fold increase in litterfall inputs to these soils coincided with a significant increase in the organic horizon C stock with warming, however, no significant difference in the surface mineral soil C stocks was observed. The younger mean age of the mineral soil C ( 70 versus 330 YBP) provided further evidence for the greater turnover of SOC in the warmer climate soils. In spite of these differences in mean radiocarbon age, mineral SOC exhibited chemical characteristics of highly decomposed material across all regions. In contrast with depth trends in soil OM diagenetic indices, diagenetic shifts with latitude were limited to increases in C:N and alkyl to O-alkyl ratios in the overlying organic horizons in the warmer relative to the colder regions. These data indicate that the

Warm-water coral reefs and climate change.

PubMed

Spalding, Mark D; Brown, Barbara E

2015-11-13

Coral reefs are highly dynamic ecosystems that are regularly exposed to natural perturbations. Human activities have increased the range, intensity, and frequency of disturbance to reefs. Threats such as overfishing and pollution are being compounded by climate change, notably warming and ocean acidification. Elevated temperatures are driving increasingly frequent bleaching events that can lead to the loss of both coral cover and reef structural complexity. There remains considerable variability in the distribution of threats and in the ability of reefs to survive or recover from such disturbances. Without significant emissions reductions, however, the future of coral reefs is increasingly bleak. Copyright © 2015, American Association for the Advancement of Science.

The potential for behavioral thermoregulation to buffer "cold-blooded" animals against climate warming.

PubMed

Kearney, Michael; Shine, Richard; Porter, Warren P

2009-03-10

Increasing concern about the impacts of global warming on biodiversity has stimulated extensive discussion, but methods to translate broad-scale shifts in climate into direct impacts on living animals remain simplistic. A key missing element from models of climatic change impacts on animals is the buffering influence of behavioral thermoregulation. Here, we show how behavioral and mass/energy balance models can be combined with spatial data on climate, topography, and vegetation to predict impacts of increased air temperature on thermoregulating ectotherms such as reptiles and insects (a large portion of global biodiversity). We show that for most "cold-blooded" terrestrial animals, the primary thermal challenge is not to attain high body temperatures (although this is important in temperate environments) but to stay cool (particularly in tropical and desert areas, where ectotherm biodiversity is greatest). The impact of climate warming on thermoregulating ectotherms will depend critically on how changes in vegetation cover alter the availability of shade as well as the animals' capacities to alter their seasonal timing of activity and reproduction. Warmer environments also may increase maintenance energy costs while simultaneously constraining activity time, putting pressure on mass and energy budgets. Energy- and mass-balance models provide a general method to integrate the complexity of these direct interactions between organisms and climate into spatial predictions of the impact of climate change on biodiversity. This methodology allows quantitative organism- and habitat-specific assessments of climate change impacts.

A climate responsive urban design tool: a platform to improve energy efficiency in a dry hot climate

NASA Astrophysics Data System (ADS)

El Dallal, Norhan; Visser, Florentine

2017-09-01

In the Middle East and North Africa (MENA) region, new urban developments should address the climatic conditions to improve outdoor comfort and to reduce the energy consumption of buildings. This article describes a design tool that supports climate responsive design for a dry hot climate. The approach takes the climate as an initiator for the conceptual urban form with a more energy-efficient urban morphology. The methodology relates the different passive strategies suitable for major climate conditions in MENA region (dry-hot) to design parameters that create the urban form. This parametric design approach is the basis for a tool that generates conceptual climate responsive urban forms so as to assist the urban designer early in the design process. Various conceptual scenarios, generated by a computational model, are the results of the proposed platform. A practical application of the approach is conducted on a New Urban Community in Aswan (Egypt), showing the economic feasibility of the resulting urban form and morphology, and the proposed tool.

Climate Change of 4°C GlobalWarming above Pre-industrial Levels

NASA Astrophysics Data System (ADS)

Wang, Xiaoxin; Jiang, Dabang; Lang, Xianmei

2018-07-01

Using a set of numerical experiments from 39 CMIP5 climate models, we project the emergence time for 4°C global warming with respect to pre-industrial levels and associated climate changes under the RCP8.5 greenhouse gas concentration scenario. Results show that, according to the 39 models, the median year in which 4°C global warming will occur is 2084. Based on the median results of models that project a 4°C global warming by 2100, land areas will generally exhibit stronger warming than the oceans annually and seasonally, and the strongest enhancement occurs in the Arctic, with the exception of the summer season. Change signals for temperature go outside its natural internal variabilities globally, and the signal-tonoise ratio averages 9.6 for the annual mean and ranges from 6.3 to 7.2 for the seasonal mean over the globe, with the greatest values appearing at low latitudes because of low noise. Decreased precipitation generally occurs in the subtropics, whilst increased precipitation mainly appears at high latitudes. The precipitation changes in most of the high latitudes are greater than the background variability, and the global mean signal-to-noise ratio is 0.5 and ranges from 0.2 to 0.4 for the annual and seasonal means, respectively. Attention should be paid to limiting global warming to 1.5°C, in which case temperature and precipitation will experience a far more moderate change than the natural internal variability. Large inter-model disagreement appears at high latitudes for temperature changes and at mid and low latitudes for precipitation changes. Overall, the intermodel consistency is better for temperature than for precipitation.

A climate trend analysis of Sudan

USGS Publications Warehouse

Funk, Christopher C.; Eilerts, Gary; Verdin, Jim; Rowland, Jim; Marshall, Michael

2011-01-01

Summer rains in western and southern Sudan have declined by 10-20 percent since the mid-1970s. Observed warming of more than 1 degree Celsius is equivalent to another 10-20 percent reduction in rainfall for crops. The warming and drying have impacted southern Darfur and areas around Juba. Rainfall declines west of Juba threaten southern Sudan's future food production prospects. In many cases, areas with changing climate are coincident with zones of substantial conflict, suggesting some degree of association; however, the contribution of climate change to these conflicts is not currently understood. Rapid population growth and the expansion of farming and pastoralism under a more variable climate regime could dramatically increase the number of at-risk people in Sudan over the next 20 years.

Changes in plant community composition lag behind climate warming in lowland forests.

PubMed

Bertrand, Romain; Lenoir, Jonathan; Piedallu, Christian; Riofrío-Dillon, Gabriela; de Ruffray, Patrice; Vidal, Claude; Pierrat, Jean-Claude; Gégout, Jean-Claude

2011-10-19

Climate change is driving latitudinal and altitudinal shifts in species distribution worldwide, leading to novel species assemblages. Lags between these biotic responses and contemporary climate changes have been reported for plants and animals. Theoretically, the magnitude of these lags should be greatest in lowland areas, where the velocity of climate change is expected to be much greater than that in highland areas. We compared temperature trends to temperatures reconstructed from plant assemblages (observed in 76,634 surveys) over a 44-year period in France (1965-2008). Here we report that forest plant communities had responded to 0.54 °C of the effective increase of 1.07 °C in highland areas (500-2,600 m above sea level), while they had responded to only 0.02 °C of the 1.11 °C warming trend in lowland areas. There was a larger temperature lag (by 3.1 times) between the climate and plant community composition in lowland forests than in highland forests. The explanation of such disparity lies in the following properties of lowland, as compared to highland, forests: the higher proportion of species with greater ability for local persistence as the climate warms, the reduced opportunity for short-distance escapes, and the greater habitat fragmentation. Although mountains are currently considered to be among the ecosystems most threatened by climate change (owing to mountaintop extinction), the current inertia of plant communities in lowland forests should also be noted, as it could lead to lowland biotic attrition. ©2011 Macmillan Publishers Limited. All rights reserved

Scenario dependence of future changes in climate extremes under 1.5 °C and 2 °C global warming

NASA Astrophysics Data System (ADS)

Wang, Zhili; Lin, Lei; Zhang, Xiaoye; Zhang, Hua; Liu, Liangke; Xu, Yangyang

2017-04-01

The 2015 Paris Agreement aims to limit global warming below 2 °C and pursue efforts to even limit it to 1.5 °C relative to pre-industrial levels. Decision makers need reliable information on the impacts caused by these warming levels for climate mitigation and adaptation measures. We explore the changes in climate extremes, which are closely tied to economic losses and casualties, under 1.5 °C and 2 °C global warming and their scenario dependence using three sets of ensemble global climate model simulations. A warming of 0.5 °C (from 1.5 °C to 2 °C) leads to significant increases in temperature and precipitation extremes in most regions. However, the projected changes in climate extremes under both warming levels highly depend on the pathways of emissions scenarios, with different greenhouse gas (GHG)/aerosol forcing ratio and GHG levels. Moreover, there are multifold differences in several heavily polluted regions, among the scenarios, in the changes in precipitation extremes due to an additional 0.5 °C warming from 1.5 °C to 2 °C. Our results demonstrate that the chemical compositions of emissions scenarios, not just the total radiative forcing and resultant warming level, must be considered when assessing the impacts of global 1.5/2 °C warming.

Scenario dependence of future changes in climate extremes under 1.5 °C and 2 °C global warming.

PubMed

Wang, Zhili; Lin, Lei; Zhang, Xiaoye; Zhang, Hua; Liu, Liangke; Xu, Yangyang

2017-04-20

The 2015 Paris Agreement aims to limit global warming below 2 °C and pursue efforts to even limit it to 1.5 °C relative to pre-industrial levels. Decision makers need reliable information on the impacts caused by these warming levels for climate mitigation and adaptation measures. We explore the changes in climate extremes, which are closely tied to economic losses and casualties, under 1.5 °C and 2 °C global warming and their scenario dependence using three sets of ensemble global climate model simulations. A warming of 0.5 °C (from 1.5 °C to 2 °C) leads to significant increases in temperature and precipitation extremes in most regions. However, the projected changes in climate extremes under both warming levels highly depend on the pathways of emissions scenarios, with different greenhouse gas (GHG)/aerosol forcing ratio and GHG levels. Moreover, there are multifold differences in several heavily polluted regions, among the scenarios, in the changes in precipitation extremes due to an additional 0.5 °C warming from 1.5 °C to 2 °C. Our results demonstrate that the chemical compositions of emissions scenarios, not just the total radiative forcing and resultant warming level, must be considered when assessing the impacts of global 1.5/2 °C warming.

Regional climate models reduce biases of global models and project smaller European summer warming

NASA Astrophysics Data System (ADS)

Soerland, S.; Schar, C.; Lüthi, D.; Kjellstrom, E.

2017-12-01

The assessment of regional climate change and the associated planning of adaptation and response strategies are often based on complex model chains. Typically, these model chains employ global and regional climate models (GCMs and RCMs), as well as one or several impact models. It is a common belief that the errors in such model chains behave approximately additive, thus the uncertainty should increase with each modeling step. If this hypothesis were true, the application of RCMs would not lead to any intrinsic improvement (beyond higher-resolution detail) of the GCM results. Here, we investigate the bias patterns (offset during the historical period against observations) and climate change signals of two RCMs that have downscaled a comprehensive set of GCMs following the EURO-CORDEX framework. The two RCMs reduce the biases of the driving GCMs, reduce the spread and modify the amplitude of the GCM projected climate change signal. The GCM projected summer warming at the end of the century is substantially reduced by both RCMs. These results are important, as the projected summer warming and its likely impact on the water cycle are among the most serious concerns regarding European climate change.

Integrating geological archives and climate models for the mid-Pliocene warm period.

PubMed

Haywood, Alan M; Dowsett, Harry J; Dolan, Aisling M

2016-02-16

The mid-Pliocene Warm Period (mPWP) offers an opportunity to understand a warmer-than-present world and assess the predictive ability of numerical climate models. Environmental reconstruction and climate modelling are crucial for understanding the mPWP, and the synergy of these two, often disparate, fields has proven essential in confirming features of the past and in turn building confidence in projections of the future. The continual development of methodologies to better facilitate environmental synthesis and data/model comparison is essential, with recent work demonstrating that time-specific (time-slice) syntheses represent the next logical step in exploring climate change during the mPWP and realizing its potential as a test bed for understanding future climate change.

Estimating the potential for adaptation of corals to climate warming.

PubMed

Császár, Nikolaus B M; Ralph, Peter J; Frankham, Richard; Berkelmans, Ray; van Oppen, Madeleine J H

2010-03-18

The persistence of tropical coral reefs is threatened by rapidly increasing climate warming, causing a functional breakdown of the obligate symbiosis between corals and their algal photosymbionts (Symbiodinium) through a process known as coral bleaching. Yet the potential of the coral-algal symbiosis to genetically adapt in an evolutionary sense to warming oceans is unknown. Using a quantitative genetics approach, we estimated the proportion of the variance in thermal tolerance traits that has a genetic basis (i.e. heritability) as a proxy for their adaptive potential in the widespread Indo-Pacific reef-building coral Acropora millepora. We chose two physiologically different populations that associate respectively with one thermo-tolerant (Symbiodinium clade D) and one less tolerant symbiont type (Symbiodinium C2). In both symbiont types, pulse amplitude modulated (PAM) fluorometry and high performance liquid chromatography (HPLC) analysis revealed significant heritabilities for traits related to both photosynthesis and photoprotective pigment profile. However, quantitative real-time polymerase chain reaction (qRT-PCR) assays showed a lack of heritability in both coral host populations for their own expression of fundamental stress genes. Coral colony growth, contributed to by both symbiotic partners, displayed heritability. High heritabilities for functional key traits of algal symbionts, along with their short clonal generation time and high population sizes allow for their rapid thermal adaptation. However, the low overall heritability of coral host traits, along with the corals' long generation time, raise concern about the timely adaptation of the coral-algal symbiosis in the face of continued rapid climate warming.

Estimating the Potential for Adaptation of Corals to Climate Warming

PubMed Central

Császár, Nikolaus B. M.; Ralph, Peter J.; Frankham, Richard; Berkelmans, Ray; van Oppen, Madeleine J. H.

2010-01-01

The persistence of tropical coral reefs is threatened by rapidly increasing climate warming, causing a functional breakdown of the obligate symbiosis between corals and their algal photosymbionts (Symbiodinium) through a process known as coral bleaching. Yet the potential of the coral-algal symbiosis to genetically adapt in an evolutionary sense to warming oceans is unknown. Using a quantitative genetics approach, we estimated the proportion of the variance in thermal tolerance traits that has a genetic basis (i.e. heritability) as a proxy for their adaptive potential in the widespread Indo-Pacific reef-building coral Acropora millepora. We chose two physiologically different populations that associate respectively with one thermo-tolerant (Symbiodinium clade D) and one less tolerant symbiont type (Symbiodinium C2). In both symbiont types, pulse amplitude modulated (PAM) fluorometry and high performance liquid chromatography (HPLC) analysis revealed significant heritabilities for traits related to both photosynthesis and photoprotective pigment profile. However, quantitative real-time polymerase chain reaction (qRT-PCR) assays showed a lack of heritability in both coral host populations for their own expression of fundamental stress genes. Coral colony growth, contributed to by both symbiotic partners, displayed heritability. High heritabilities for functional key traits of algal symbionts, along with their short clonal generation time and high population sizes allow for their rapid thermal adaptation. However, the low overall heritability of coral host traits, along with the corals' long generation time, raise concern about the timely adaptation of the coral-algal symbiosis in the face of continued rapid climate warming. PMID:20305781

How warm days increase belief in global warming

NASA Astrophysics Data System (ADS)

Zaval, Lisa; Keenan, Elizabeth A.; Johnson, Eric J.; Weber, Elke U.

2014-02-01

Climate change judgements can depend on whether today seems warmer or colder than usual, termed the local warming effect. Although previous research has demonstrated that this effect occurs, studies have yet to explain why or how temperature abnormalities influence global warming attitudes. A better understanding of the underlying psychology of this effect can help explain the public's reaction to climate change and inform approaches used to communicate the phenomenon. Across five studies, we find evidence of attribute substitution, whereby individuals use less relevant but available information (for example, today's temperature) in place of more diagnostic but less accessible information (for example, global climate change patterns) when making judgements. Moreover, we rule out alternative hypotheses involving climate change labelling and lay mental models. Ultimately, we show that present temperature abnormalities are given undue weight and lead to an overestimation of the frequency of similar past events, thereby increasing belief in and concern for global warming.

Warm Rain Processes Over the Tropical Oceans and Implications on Climate Change: Results from TRMM and GOES GCM

NASA Technical Reports Server (NTRS)

Lau, William K. M.; Wu, H. T.

2004-01-01

In this talk, we will first show results from TRMM data regarding the characteristics of warm rains over the tropical oceans, and the dependence of rate of warm rain production on sea surface temperature. Results lead to the hypothesis that warm rain production efficiency, i.e., autoconversion, may be increased in a warm climate. We use the GEOS-II GCM to test this hypothesis. Our modeling results show that in a climate with increased rate of autoconversion, the total rain amount is increased, with warm rain contributing to a larger portion of the increase. The abundant rainout of warm precipitation causes a reduction of low and middle cloud amount due to rainout, and reduced high clouds due to less water vapor available for ice-phase convection. However, clod radiation feedback caused by the increased rainfall efficiency, leads to differential vertical heating/cooling producing a more unstable atmosphere, allowing, more intense, but isolated penetrative convection, with contracted anvils to develop. Results also show that increased autoconversion reduces the convective adjustment time scale, resulting in faster recycling of atmospheric water. Most interestingly, the increased low level heating associated with warm rain leads to more energetic Madden and Julian oscillations in the tropics, with well-defined eastward propagation. While reducing the autoconversion leads to an abundant mix of westward and eastward tropical disturbances on daily to weekly time scales. The crucial link of precipitation microphysical processes to climate change including the effects of aerosols will be discussed.

Warm Rain Processes over the Tropical Oceans and Implications on Climate Change: Results from TRMM and GEOS GCM

NASA Technical Reports Server (NTRS)

Lau, William K. M.; Wu, H. T.

2004-01-01

In this talk, we will first show results from TRMM data regarding the characteristics of warm rains over the tropical oceans, and the dependence of rate of warm rain production on sea surface temperature. Results lead to the hypothesis that warm rain production efficiency, i.e., autoconversion, may be increased in a warm climate. We use the GEOS-II GCM to test this hypothesis. Our modeling results show that in a climate with increased rate of autoconversion, the total rain amount is increased, with warm rain contributing to larger portion of the increase. The abundant rainout of warm precipitation causes a reduction of low and middle cloud amount due to rainout, and reduced high clouds due to less water vapor available for ice-phase convection. However, clod radiation feedback caused by the increased rainfall efficiency, leads to differential vertical heating/cooling producing a more unstable atmosphere, allowing, more intense, but isolated penetrative convection, with contracted anvils to develop. Results also show that increased autoconversion reduces the convective adjustment time scale, resulting in faster recycling of atmospheric water. Most interestingly, the increased low level heating associated with warm rain leads to more energetic Madden and Julian oscillations in the tropics, with well-defined eastward propagation. While reducing the autoconversion leads to an abundant mix of westward and eastward tropical disturbances on daily to weekly time scales. The crucial link of precipitation microphysical processes to climate change including the effects of aerosols will be discussed.

Medical Providers as Global Warming and Climate Change Health Educators: A Health Literacy Approach

ERIC Educational Resources Information Center

Villagran, Melinda; Weathers, Melinda; Keefe, Brian; Sparks, Lisa

2010-01-01

Climate change is a threat to wildlife and the environment, but it also one of the most pervasive threats to human health. The goal of this study was to examine the relationships among dimensions of health literacy, patient education about global warming and climate change (GWCC), and health behaviors. Results reveal that patients who have higher…

Investigate the plant biomass response to climate warming in permafrost ecosystem using matrix-based data assimilation

NASA Astrophysics Data System (ADS)

Lu, X.; Du, Z.; Schuur, E.; Luo, Y.

2017-12-01

Permafrost is one of the most vulnerable regions on the earth with over 40% world soil C represented in this region. Future climate warming potentially has a great impact on this region. On one hand, rising temperature accelerates permafrost soil thaw and release more C from land. On the other hand, warming may also increase the plant growing season length and therefore negatively feedback to climate change by increasing annual land C uptake. However, whether permafrost vegetation biomass change in response to warming can sequester more C has not been well understood. Manipulated air warming experiments reported that air warming has very limited impacts on grass land productivity and biomass growth in permafrost region [Mauritz et al., 2017]. It is hard to reveal the mechanisms behind the limited air warming response directly from experiment data. We employ a vegetation C cycle matrix model based on Community land model 4.5 (CLM4.5) and data assimilation technique to investigate how much do phenology and physiology processes contribute to the response respectively. Our results indicate phenology contributes the most in response to warming. The shift of vegetation parameter distributions after 2012 indicate vegetation acclimation may explain the modest response in plant biomass to air warming. The results suggest future model development need to take vegetation acclimation more seriously. The novel matrix-based model allows data assimilation to be conducted more efficiently. It provides more functional understanding of the models as well as the mechanism behind experiment data.

Commonalities of carbon dioxide exchange in semiarid regions with monsoon and Mediterranean climates

USDA-ARS?s Scientific Manuscript database

Semiarid ecosystems with monsoon climates receive precipitation during the warm season while Mediterranean systems are characteristically wet in the cool season and dry in the summer. Comparing biosphere-atmosphere carbon exchange across these two climate regimes can yield information about the int...

Deacclimation may be crucial for winter survival of cereals under warming climate.

PubMed

Rapacz, Marcin; Jurczyk, Barbara; Sasal, Monika

2017-03-01

Climate warming can change the winter weather patterns. Warmer temperatures during winter result in a lower risk of extreme freezing events. On the other hand the predicted warm gaps during winter will decrease their freezing tolerance. Both contradict effects will affect winter survival but their resultant effect is unclear. In this paper, we demonstrate that climate warming may result in a decrease in winter survival of plants. A field study of winterhardiness of common wheat and triticale was established at 11 locations and repeated during three subsequent winters. The freezing tolerance of the plants was studied after controlled cold acclimation and de-acclimation using both plant survival analysis and chlorophyll fluorescence measurements. Cold deacclimation resistance was shown to be independent from cold acclimation ability. Further, cold deacclimation resistance appeared to be crucial for overwintering when deacclimation conditions occurred in the field. The shortening of uninterrupted cold acclimation may increase cold deacclimation efficiency, which could threaten plant survival during warmer winters. Measurements of chlorophyll fluorescence transient showed some differences triggered by freezing before and after deacclimation. We conclude that cold deacclimation resistance should be considered in the breeding of winter cereals and in future models of winter damage risk. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Vulnerability to climate warming of Liolaemus pictus (Squamata, Liolaemidae), a lizard from the cold temperate climate in Patagonia, Argentina.

PubMed

Kubisch, Erika Leticia; Fernández, Jimena Beatriz; Ibargüengoytía, Nora Ruth

2016-02-01

The vulnerability of populations and species to global warming depends not only on the environmental temperatures, but also on the behavioral and physiological abilities to respond to these changes. In this sense, the knowledge of an organism's sensitivity to temperature variation is essential to predict potential responses to climate warming. In particular, it is interesting to know how close species are to their thermal limits in nature and whether physiological plasticity is a potential short-term response to warming climates. We exposed Liolaemus pictus lizards, from northern Patagonia, to either 21 or 31 °C for 30 days to compare the effects of these treatments on thermal sensitivity in 1 and 0.2 m runs, preferred body temperature (T pref), panting threshold (T pant), and critical minimum temperature (CTMin). Furthermore, we measured the availability of thermal microenvironments (operative temperatures; T e) to measure how close L. pictus is, in nature, to its optimal locomotor performance (T o) and thermal limits. L. pictus showed limited physiological plasticity, since the acclimation temperature (21 and 31 °C) did not affect the locomotor performance nor did it affect T pref, the T pant, or the CTMin. The mean T e was close to T o and was 17 °C lower than the CTMax. The results suggest that L. pictus, in a climate change scenario, could be vulnerable to the predicted temperature increment, as this species currently lives in an environment with temperatures close to their highest locomotor temperature threshold, and because they showed limited acclimation capacity to adjust to new thermal conditions by physiological plasticity. Nevertheless, L. pictus can run at 80 % or faster of its maximum speed across a wide range of temperatures near T o, an ability which would attenuate the impact of global warming.

Climatic and ecological future of the Amazon: likelihood and causes of change

NASA Astrophysics Data System (ADS)

Cook, B.; Zeng, N.; Yoon, J.-H.

2010-05-01

Some recent climate modeling results suggested a possible dieback of the Amazon rainforest under future climate change, a prediction that raised considerable interest as well as controversy. To determine the likelihood and causes of such changes, we analyzed the output of 15 models from the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC/AR4) and a dynamic vegetation model VEGAS driven by these climate output. Our results suggest that the core of the Amazon rainforest should remain largely stable as rainfall is projected to increase in nearly all models. However, the periphery, notably the southern edge of the Amazon and further south in central Brazil, are in danger of drying out, driven by two main processes. Firstly, a decline in precipitation of 22% in the southern Amazon's dry season (May-September) reduces soil moisture, despite an increase in precipitation during the wet season, due to nonlinear responses in hydrology and ecosystem dynamics. Two dynamical mechanisms may explain the lower dry season rainfall: (1) a general subtropical drying under global warming when the dry season southern Amazon is under the control of the subtropical high pressure; (2) a stronger north-south tropical Atlantic sea surface temperature gradient, and to lesser degree a warmer eastern equatorial Pacific. Secondly, evaporation demand will increase due to the general warming, further reducing soil moisture. In terms of ecosystem response, higher maintenance cost and reduced productivity under warming may also have additional adverse impact. The drying corresponds to a lengthening of the dry season by 11 days. As a consequence, the median of the models projects a reduction of 20% in vegetation carbon stock in the southern Amazon, central Brazil, and parts of the Andean Mountains. Further, VEGAS predicts enhancement of fire risk by 10-15%. The increase in fire is primarily due to the reduction in soil moisture, and the decrease in dry season rainfall, which

Human-water interactions in Myanmar's Dry Zone under climate change

NASA Astrophysics Data System (ADS)

Taft, Linda; Evers, Mariele

2016-04-01

Understanding human-water interactions is particularly essential in countries where the economy and the people's well-being and income strongly depend on the availability and quality of sufficient water resources. Such a strong dependency on water is existent in Myanmar's Dry Zone located in the central Ayeyarwady River basin. In this area, rainfall is associated with high heterogeneity across space and time. Precipitation amounts in the Dry Zone (500-1000 mm annually) are generally less compared to other regions in Myanmar (up to 4000-6000 mm). Following the Global Climate Risk Index, Myanmar is one of the countries which were most affected by extreme weather events between 1994 and 2013. Severe drought periods e.g in the years 1997-1998, 2010 and 2014 led to crop failures and water shortage in the Dry Zone, where more than 14 mio people predominantly practice agriculture. Due to the high variability of rainfalls, farming is only possible with irrigation, mainly conducted by canal systems from the rivers and groundwater withdrawal. Myanmar is recently facing big challenges which result from comprehensive political and economic reforms since 2011. These may also include increasing water use by new industrial zones and urbanization. However, not only policy and economy modify the need for water. Variability of river runoff and changes in seasonality are expected as a result of climate change. The overarching goal of the study is to understand and increase the knowledge on human-water-climate interactions and to elaborate possible future scenarios for Myanmar's Dry Zone. It is not well studied yet how current and future climate change and increasing human impact will influence the country's abundant water resources including groundwater. Therefore, the first step of this study is to identify the major drivers within the central Ayeyarwady River basin. We are in the process of collecting and analyzing data sets and information including hydrologic and eco

Plants, birds and butterflies: short-term responses of species communities to climate warming vary by taxon and with altitude.

PubMed

Roth, Tobias; Plattner, Matthias; Amrhein, Valentin

2014-01-01

As a consequence of climate warming, species usually shift their distribution towards higher latitudes or altitudes. Yet, it is unclear how different taxonomic groups may respond to climate warming over larger altitudinal ranges. Here, we used data from the national biodiversity monitoring program of Switzerland, collected over an altitudinal range of 2500 m. Within the short period of eight years (2003-2010), we found significant shifts in communities of vascular plants, butterflies and birds. At low altitudes, communities of all species groups changed towards warm-dwelling species, corresponding to an average uphill shift of 8 m, 38 m and 42 m in plant, butterfly and bird communities, respectively. However, rates of community changes decreased with altitude in plants and butterflies, while bird communities changed towards warm-dwelling species at all altitudes. We found no decrease in community variation with respect to temperature niches of species, suggesting that climate warming has not led to more homogenous communities. The different community changes depending on altitude could not be explained by different changes of air temperatures, since during the 16 years between 1995 and 2010, summer temperatures in Switzerland rose by about 0.07°C per year at all altitudes. We discuss that land-use changes or increased disturbances may have prevented alpine plant and butterfly communities from changing towards warm-dwelling species. However, the findings are also consistent with the hypothesis that unlike birds, many alpine plant species in a warming climate could find suitable habitats within just a few metres, due to the highly varied surface of alpine landscapes. Our results may thus support the idea that for plants and butterflies and on a short temporal scale, alpine landscapes are safer places than lowlands in a warming world.

Plants, Birds and Butterflies: Short-Term Responses of Species Communities to Climate Warming Vary by Taxon and with Altitude

PubMed Central

Roth, Tobias; Plattner, Matthias; Amrhein, Valentin

2014-01-01

As a consequence of climate warming, species usually shift their distribution towards higher latitudes or altitudes. Yet, it is unclear how different taxonomic groups may respond to climate warming over larger altitudinal ranges. Here, we used data from the national biodiversity monitoring program of Switzerland, collected over an altitudinal range of 2500 m. Within the short period of eight years (2003–2010), we found significant shifts in communities of vascular plants, butterflies and birds. At low altitudes, communities of all species groups changed towards warm-dwelling species, corresponding to an average uphill shift of 8 m, 38 m and 42 m in plant, butterfly and bird communities, respectively. However, rates of community changes decreased with altitude in plants and butterflies, while bird communities changed towards warm-dwelling species at all altitudes. We found no decrease in community variation with respect to temperature niches of species, suggesting that climate warming has not led to more homogenous communities. The different community changes depending on altitude could not be explained by different changes of air temperatures, since during the 16 years between 1995 and 2010, summer temperatures in Switzerland rose by about 0.07°C per year at all altitudes. We discuss that land-use changes or increased disturbances may have prevented alpine plant and butterfly communities from changing towards warm-dwelling species. However, the findings are also consistent with the hypothesis that unlike birds, many alpine plant species in a warming climate could find suitable habitats within just a few metres, due to the highly varied surface of alpine landscapes. Our results may thus support the idea that for plants and butterflies and on a short temporal scale, alpine landscapes are safer places than lowlands in a warming world. PMID:24416144

Scenario dependence of future changes in climate extremes under 1.5 °C and 2 °C global warming

PubMed Central

Wang, Zhili; Lin, Lei; Zhang, Xiaoye; Zhang, Hua; Liu, Liangke; Xu, Yangyang

2017-01-01

The 2015 Paris Agreement aims to limit global warming below 2 °C and pursue efforts to even limit it to 1.5 °C relative to pre-industrial levels. Decision makers need reliable information on the impacts caused by these warming levels for climate mitigation and adaptation measures. We explore the changes in climate extremes, which are closely tied to economic losses and casualties, under 1.5 °C and 2 °C global warming and their scenario dependence using three sets of ensemble global climate model simulations. A warming of 0.5 °C (from 1.5 °C to 2 °C) leads to significant increases in temperature and precipitation extremes in most regions. However, the projected changes in climate extremes under both warming levels highly depend on the pathways of emissions scenarios, with different greenhouse gas (GHG)/aerosol forcing ratio and GHG levels. Moreover, there are multifold differences in several heavily polluted regions, among the scenarios, in the changes in precipitation extremes due to an additional 0.5 °C warming from 1.5 °C to 2 °C. Our results demonstrate that the chemical compositions of emissions scenarios, not just the total radiative forcing and resultant warming level, must be considered when assessing the impacts of global 1.5/2 °C warming. PMID:28425445

Thermal tolerance and climate warming sensitivity in tropical snails.

PubMed

Marshall, David J; Rezende, Enrico L; Baharuddin, Nursalwa; Choi, Francis; Helmuth, Brian

2015-12-01

Tropical ectotherms are predicted to be especially vulnerable to climate change because their thermal tolerance limits generally lie close to current maximum air temperatures. This prediction derives primarily from studies on insects and lizards and remains untested for other taxa with contrasting ecologies. We studied the HCT (heat coma temperatures) and ULT (upper lethal temperatures) of 40 species of tropical eulittoral snails (Littorinidae and Neritidae) inhabiting exposed rocky shores and shaded mangrove forests in Oceania, Africa, Asia and North America. We also estimated extremes in animal body temperature at each site using a simple heat budget model and historical (20 years) air temperature and solar radiation data. Phylogenetic analyses suggest that HCT and ULT exhibit limited adaptive variation across habitats (mangroves vs. rocky shores) or geographic locations despite their contrasting thermal regimes. Instead, the elevated heat tolerance of these species (HCT = 44.5 ± 1.8°C and ULT = 52.1 ± 2.2°C) seems to reflect the extreme temperature variability of intertidal systems. Sensitivity to climate warming, which was quantified as the difference between HCT or ULT and maximum body temperature, differed greatly between snails from sunny (rocky shore; Thermal Safety Margin, TSM = -14.8 ± 3.3°C and -6.2 ± 4.4°C for HCT and ULT, respectively) and shaded (mangrove) habitats (TSM = 5.1 ± 3.6°C and 12.5 ± 3.6°C). Negative TSMs in rocky shore animals suggest that mortality is likely ameliorated during extreme climatic events by behavioral thermoregulation. Given the low variability in heat tolerance across species, habitat and geographic location account for most of the variation in TSM and may adequately predict the vulnerability to climate change. These findings caution against generalizations on the impact of global warming across ectothermic taxa and highlight how the consideration of nonmodel animals, ecological transitions

Observed warming over northern South America has an anthropogenic origin

NASA Astrophysics Data System (ADS)

Barkhordarian, Armineh; von Storch, Hans; Zorita, Eduardo; Loikith, Paul C.; Mechoso, Carlos R.

2017-10-01

We investigate whether the recently observed trends in daily maximum and minimum near-surface air temperature (Tmax and Tmin, respectively) over South America (SA) are consistent with the simulated response of Tmin and Tmax to anthropogenic forcing. Results indicate that the recently observed warming in the dry seasons is well beyond the range of natural (internal) variability. In the wet season the natural modes of variability explain a substantial portion of Tmin and Tmax variability. We demonstrate that the large-scale component of greenhouse gas (GHG) forcing is detectable in dry-seasonal warming. However, none of the global and regional climate change projections reproduce the observed warming of up to 0.6 K/Decade in Tmax in 1983-2012 over northern SA during the austral spring (SON). Thus, besides the global manifestation of GHG forcing, other external drivers have an imprint. Using aerosols-only forcing simulations, our results provide evidence that anthropogenic aerosols also have a detectable influence in SON and that the indirect effect of aerosols on cloud's lifetime is more compatible with the observed record. In addition, there is an increasing trend in the observed incoming solar radiation over northern SA in SON, which is larger than expected from natural (internal) variability alone. We further show that in the dry seasons the spread of projected trends based on the RCP4.5 scenario derived from 30 CMIP5 models encompasses the observed area-averaged trends in Tmin and Tmax. This may imply that the observed excessive warming in the dry seasons serve as an illustration of plausible future expected change in the region.

Differential climate impacts for policy-relevant limits to global warming: the case of 1.5 °C and 2 °C

NASA Astrophysics Data System (ADS)

Schleussner, Carl-Friedrich; Lissner, Tabea K.; Fischer, Erich M.; Wohland, Jan; Perrette, Mahé; Golly, Antonius; Rogelj, Joeri; Childers, Katelin; Schewe, Jacob; Frieler, Katja; Mengel, Matthias; Hare, William; Schaeffer, Michiel

2016-04-01

Robust appraisals of climate impacts at different levels of global-mean temperature increase are vital to guide assessments of dangerous anthropogenic interference with the climate system. The 2015 Paris Agreement includes a two-headed temperature goal: "holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 °C". Despite the prominence of these two temperature limits, a comprehensive overview of the differences in climate impacts at these levels is still missing. Here we provide an assessment of key impacts of climate change at warming levels of 1.5 °C and 2 °C, including extreme weather events, water availability, agricultural yields, sea-level rise and risk of coral reef loss. Our results reveal substantial differences in impacts between a 1.5 °C and 2 °C warming that are highly relevant for the assessment of dangerous anthropogenic interference with the climate system. For heat-related extremes, the additional 0.5 °C increase in global-mean temperature marks the difference between events at the upper limit of present-day natural variability and a new climate regime, particularly in tropical regions. Similarly, this warming difference is likely to be decisive for the future of tropical coral reefs. In a scenario with an end-of-century warming of 2 °C, virtually all tropical coral reefs are projected to be at risk of severe degradation due to temperature-induced bleaching from 2050 onwards. This fraction is reduced to about 90 % in 2050 and projected to decline to 70 % by 2100 for a 1.5 °C scenario. Analyses of precipitation-related impacts reveal distinct regional differences and hot-spots of change emerge. Regional reduction in median water availability for the Mediterranean is found to nearly double from 9 % to 17 % between 1.5 °C and 2 °C, and the projected lengthening of regional dry spells increases from 7 to 11 %. Projections for

Comparing Effects of Climate Warming, Fire, and Timber Harvesting on a Boreal Forest Landscape in Northeastern China

PubMed Central

Li, Xiaona; He, Hong S.; Wu, Zhiwei; Liang, Yu; Schneiderman, Jeffrey E.

2013-01-01

Forest management under a changing climate requires assessing the effects of climate warming and disturbance on the composition, age structure, and spatial patterns of tree species. We investigated these effects on a boreal forest in northeastern China using a factorial experimental design and simulation modeling. We used a spatially explicit forest landscape model (LANDIS) to evaluate the effects of three independent variables: climate (current and expected future), fire regime (current and increased fire), and timber harvesting (no harvest and legal harvest). Simulations indicate that this forested landscape would be significantly impacted under a changing climate. Climate warming would significantly increase the abundance of most trees, especially broadleaf species (aspen, poplar, and willow). However, climate warming would have less impact on the abundance of conifers, diversity of forest age structure, and variation in spatial landscape structure than burning and harvesting. Burning was the predominant influence in the abundance of conifers except larch and the abundance of trees in mid-stage. Harvesting impacts were greatest for the abundance of larch and birch, and the abundance of trees during establishment stage (1–40 years), early stage (41–80 years) and old- growth stage (>180 years). Disturbance by timber harvesting and burning may significantly alter forest ecosystem dynamics by increasing forest fragmentation and decreasing forest diversity. Results from the simulations provide insight into the long term management of this boreal forest. PMID:23573209

Comparing effects of climate warming, fire, and timber harvesting on a boreal forest landscape in northeastern China.

PubMed

Li, Xiaona; He, Hong S; Wu, Zhiwei; Liang, Yu; Schneiderman, Jeffrey E

2013-01-01

Forest management under a changing climate requires assessing the effects of climate warming and disturbance on the composition, age structure, and spatial patterns of tree species. We investigated these effects on a boreal forest in northeastern China using a factorial experimental design and simulation modeling. We used a spatially explicit forest landscape model (LANDIS) to evaluate the effects of three independent variables: climate (current and expected future), fire regime (current and increased fire), and timber harvesting (no harvest and legal harvest). Simulations indicate that this forested landscape would be significantly impacted under a changing climate. Climate warming would significantly increase the abundance of most trees, especially broadleaf species (aspen, poplar, and willow). However, climate warming would have less impact on the abundance of conifers, diversity of forest age structure, and variation in spatial landscape structure than burning and harvesting. Burning was the predominant influence in the abundance of conifers except larch and the abundance of trees in mid-stage. Harvesting impacts were greatest for the abundance of larch and birch, and the abundance of trees during establishment stage (1-40 years), early stage (41-80 years) and old- growth stage (>180 years). Disturbance by timber harvesting and burning may significantly alter forest ecosystem dynamics by increasing forest fragmentation and decreasing forest diversity. Results from the simulations provide insight into the long term management of this boreal forest.

Carbon dioxide flux and net primary production of a boreal treed bog: Responses to warming and water-table-lowering simulations of climate change

NASA Astrophysics Data System (ADS)

Munir, T. M.; Perkins, M.; Kaing, E.; Strack, M.

2015-02-01

Midlatitude treed bogs represent significant carbon (C) stocks and are highly sensitive to global climate change. In a dry continental treed bog, we compared three sites: control, recent (1-3 years; experimental) and older drained (10-13 years), with water levels at 38, 74 and 120 cm below the surface, respectively. At each site we measured carbon dioxide (CO2) fluxes and estimated tree root respiration (Rr; across hummock-hollow microtopography of the forest floor) and net primary production (NPP) of trees during the growing seasons (May to October) of 2011-2013. The CO2-C balance was calculated by adding the net CO2 exchange of the forest floor (NEff-Rr) to the NPP of the trees. From cooler and wetter 2011 to the driest and the warmest 2013, the control site was a CO2-C sink of 92, 70 and 76 g m-2, the experimental site was a CO2-C source of 14, 57 and 135 g m-2, and the drained site was a progressively smaller source of 26, 23 and 13 g CO2-C m-2. The short-term drainage at the experimental site resulted in small changes in vegetation coverage and large net CO2 emissions at the microforms. In contrast, the longer-term drainage and deeper water level at the drained site resulted in the replacement of mosses with vascular plants (shrubs) on the hummocks and lichen in the hollows leading to the highest CO2 uptake at the drained hummocks and significant losses in the hollows. The tree NPP (including above- and below-ground growth and litter fall) in 2011 and 2012 was significantly higher at the drained site (92 and 83 g C m-2) than at the experimental (58 and 55 g C m-2) and control (52 and 46 g C m-2) sites. We also quantified the impact of climatic warming at all water table treatments by equipping additional plots with open-top chambers (OTCs) that caused a passive warming on average of ~ 1 °C and differential air warming of ~ 6 °C at midday full sun over the study years. Warming significantly enhanced shrub growth and the CO2 sink function of the drained

Assessing Lebanon's wildfire potential in association with current and future climatic conditions

Treesearch

George H. Mitri; Mireille G. Jazi; David McWethy

2015-01-01

The increasing occurrence and extent of large-scale wildfires in the Mediterranean have been linked to extended periods of warm and dry weather. We set out to assess Lebanon's wildfire potential in association with current and future climatic conditions. The Keetch-Byram Drought Index (KBDI) was the primary climate variable used in our evaluation of climate/fire...

Topography and age mediate the growth responses of Smith fir to climate warming in the southeastern Tibetan Plateau

NASA Astrophysics Data System (ADS)

Liu, B.; Wang, Y.; Zhu, H.; Liang, E.; Camarero, J. J.

2016-10-01

The Tibetan Plateau holds some of the world's highest undisturbed natural treelines and timberlines. Such extreme environments constitute potentially valuable monitoring sites of the effects of climate warming on high-elevation forests. Here, we analyze a network of 21 Smith fir forests situated in the Sygera Mountains, southeastern Tibetan Plateau, using tree-ring width (TRW) and basal area increment (BAI) chronologies. Sampled sites encompassed a wide elevation gradient, from 3600 to 4400 m, including some treeline sites and diverse aspects and tree ages. In comparison with TRW series, BAI series better capture the long-term warming signal. Previous November and current April and summer temperatures are the dominant climatic factors controlling Smith fir radial growth. The mean inter-series correlations of TRW increased upwards, but the forest limit presented the highest potential to reconstruct past temperature variability. Moreover, the growth responses of young trees were less stable than those of trees older than 100 years. Climate warming is accelerating radial growth of Smith fir forest subjected to mesic conditions. Collectively, these findings confirm that the effects of site elevation and tree age should be considered when quantifying climate-growth relationships. The type of tree-ring data (BAI vs. TRW) is also relevant since BAI indices seem to be a better climatic proxy of low-frequency temperature signals than TRW indices. Therefore, site (e.g., elevation) and tree (e.g., age) features should be considered to properly evaluate the effects of climate warming on growth of high-elevation forests.

Integrating geological archives and climate models for the mid-Pliocene warm period

PubMed Central

Haywood, Alan M.; Dowsett, Harry J.; Dolan, Aisling M.

2016-01-01

The mid-Pliocene Warm Period (mPWP) offers an opportunity to understand a warmer-than-present world and assess the predictive ability of numerical climate models. Environmental reconstruction and climate modelling are crucial for understanding the mPWP, and the synergy of these two, often disparate, fields has proven essential in confirming features of the past and in turn building confidence in projections of the future. The continual development of methodologies to better facilitate environmental synthesis and data/model comparison is essential, with recent work demonstrating that time-specific (time-slice) syntheses represent the next logical step in exploring climate change during the mPWP and realizing its potential as a test bed for understanding future climate change. PMID:26879640

Response of the North American corn belt to climate warming, CO2

NASA Astrophysics Data System (ADS)

1983-08-01

The climate of the North American corn belt was characterized to estimate the effects of climatic change on that agricultural region. Heat and moisture characteristics of the current corn belt were identified and mapped based on a simulated climate for a doubling of atmospheric CO2 concentrations. The result was a map of the projected corn belt corresponding to the simulated climatic change. Such projections were made with and without an allowance for earlier planting dates that could occur under a CO2-induced climatic warming. Because the direct effects of CO2 increases on plants, improvements in farm technology, and plant breeding are not considered, the resulting projections represent an extreme or worst case. The results indicate that even for such a worst case, climatic conditions favoring corn production would not extend very far into Canada. Climatic buffering effects of the Great Lakes would apparently retard northeastward shifts in corn-belt location.

Impact of a global warming on biospheric sources of methane and its climatic consequences

NASA Technical Reports Server (NTRS)

Hameed, S.; Cess, R. D.

1980-01-01

Most of atmospheric methane originates by bacterial processes in anaerobic environments within the soil which are found to become more productive with increases in ambient temperature. A warming of climate, due to increasing levels of industrial gases resulting from fossil fuel burning, is thus likely to increase methane abundance within the atmosphere. This may lead to further heating of the atmosphere, since both methane and ozone (which is generated in the troposphere from reactions of methane) have greenhouse effects. This feedback mechanism has been explored with the use of a coupled climate-chemical model of the troposphere, by the calculation of the impact of the predicted global warming due to increased emissions of carbon dioxide and other industrial gases on the biospheric sources of methane.

The long view: Causes of climate change over the instrumental period

NASA Astrophysics Data System (ADS)

Hegerl, G. C.; Schurer, A. P.; Polson, D.; Iles, C. E.; Bronnimann, S.

2016-12-01

The period of instrumentally recorded data has seen remarkable changes in climate, with periods of rapid warming, and periods of stagnation or cooling. A recent analysis of the observed temperature change from the instrumental record confirms that most of the warming recorded since the middle of the 20rst century has been caused by human influences, but shows large uncertainty in separating greenhouse gas from aerosol response if accounting for model uncertainty. The contribution by natural forcing and internal variability to the recent warming is estimated to be small, but becomes more important when analysing climate change over earlier or shorter time periods. For example, the enigmatic early 20th century warming was a period of strong climate anomalies, including the US dustbowl drought and exceptional heat waves, and pronounced Arctic warming. Attribution results suggests that about half of the global warming 1901-1950 was forced by greenhouse gases increases, with an anomalously strong contribution by climate variability, and contributions by natural forcing. Long term variations in circulation are important for some regional climate anomalies. Precipitation is important for impacts of climate change and precipitation changes are uncertain in models. Analysis of the instrumental record suggests a human influence on mean and heavy precipitation, and supports climate model estimates of the spatial pattern of precipitation sensitivity to warming. Broadly, and particularly over ocean, wet regions are getting wetter and dry regions are getting drier. In conclusion, the historical record provides evidence for a strong response to external forcings, supports climate models, and raises questions about multi-decadal variability.

Biocrusts modulate warming and rainfall exclusion effects on soil respiration in a semi-arid grassland