Search USGS⌕ Search

SEARCH · Search USGS

Results for “Climate”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources
USGS2016

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

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.

Limnology and Oceanography Letters↗
USGS2024

Cold blood in warming waters: Effects of air temperature, precipitation, and groundwater on Gulf Sturgeon thermal habitats in a changing climate

Objective In a changing climate, the effects of air temperature, precipitation, and groundwater on water temperature and thermal habitat suitability for Gulf Sturgeon Acipenser desotoi , listed as threatened under the U.S. Endangered Species Act, are not well understood. Hence, we incorporated these factors into thermal habitat models to forecast how Gulf Sturgeon may be affected by wide‐ranging climate change scenarios in 2024–2074. Methods Using data from the Choctawhatchee River, Florida, we developed precipitation‐ and groundwater‐corrected air–water temperature models, compared their accuracy with that of conventional air–water temperature models used in fisheries management, and projected future Gulf Sturgeon thermal habitat suitability for normal physiological functioning and fieldwork (i.e., population sampling and telemetry surgeries) in summer (May–August) under 16 climate change scenarios. Result Precipitation‐ and groundwater‐corrected models were more accurate than conventional air–water temperature models (mean improvement in adjusted R 2 = +0.45; range = +0.09 to +0.75). Water temperature was projected to warm at widely variable rates across climate change scenarios encompassing different air temperature, precipitation, and groundwater regimes. Importantly, Gulf Sturgeon summer aggregation areas were cooler and influenced more by precipitation and groundwater and less by air temperature than were non‐aggregation areas. If precipitation and groundwater—as drivers of cooling—become warm in a changing climate, summer aggregation areas were projected to exhibit thermal habitat degradation equivalent to or greater than that of non‐aggregation areas. Conclusion Our results add hydrological context to the premise that aggregation areas provide cool water and energetic savings for Gulf Sturgeon during summer, underscoring the importance of protecting these habitats through groundwater conservation, water quality monitoring, and riparian/watershed habitat management. Our findings indicate that identifying thermally appropriate times for fieldwork activities will be increasingly important and time‐restricted as climate change intensifies. However, our research provides managers with a portfolio of water temperature models and an accurate, cost‐effective, management‐relevant approach to forecasting thermal habitat conditions for Gulf Sturgeon and other species in a changing climate.

Alabama, Florida↗
USGS2017

Late quaternary vegetation and climatic history of the Long Valley area, west-central Idaho, U.S.A.

Paleoenvironmental data, including pollen and sediment analyses, radiocarbon ages, and tephra identifications of a core recovered from a fen, provide a ca. 16,500 14C yr B.P. record of late Quaternary vegetation and climate change in the Long Valley area of west-central Idaho. The fen was deglaciated prior to ca. 16,500 14C yr B.P., after which the pollen rain was dominated by Artemisia, suggesting that a cold, dry climate prevailed until ca. 12,200 14C yr B.P. From ca. 12,200 to 9750 14C yr B.P. temperatures gradually increased and a cool, moist climate similar to the present prevailed. During this period a closed spruce-pine forest surrounded the fen. This cool, moist climate was briefly interrupted by a dry and/or cold interval between ca. 10,800 and 10,400 14C yr B.P. that may be related to the Younger Dryas climatic oscillation. From ca. 9750 to 3200 14C yr B.P. the regional climate was significantly warmer and drier than at present and an open pine forest dominated the area around the fen. Maximum aridity occurred after the deposition of the Mazama tephra (ca. 6730 14C yr B.P). After 3200 14C yr B.P. regional cooling brought cool, moist conditions to the area; the establishment of the modern montane forest around the fen and present-day cool and moist climate began at ca. 2000 14C yr B.P. ?? 2001 University of Washington.

Quaternary Research↗
USGS2017

Effects of climate change on ecological disturbance in the northern Rockies

Disturbances alter ecosystem, community, or population structure and change elements of the biological and/or physical environment. Climate changes can alter the timing, magnitude, frequency, and duration of disturbance events, as well as the interactions of disturbances on a landscape, and climate change may already be affecting disturbance events and regimes. Interactions among disturbance regimes, such as the cooccurrence in space and time of bark beetle outbreaks and wildfires, can result in highly visible, rapidly occurring, and persistent changes in landscape composition and structure. Understanding how altered disturbance patterns and multiple disturbance interactions might result in novel and emergent landscape behaviors is critical for addressing climate change impacts and for designing land management strategies that are appropriate for future climates This chapter describes the ecology of important disturbance regimes in the Northern Rockies region, and potential shifts in these regimes as a consequence of observed and projected climate change. We summarize five disturbance types present in the Northern Rockies that are sensitive to a changing climate--wildfires, bark beetles, white pine blister rust (Cronartium ribicola), other forest diseases, and nonnative plant invasions—and provide information that can help managers anticipate how, when, where, and why climate changes may alter the characteristics of disturbance regimes.

Rocky Mountains↗
USGS2012

A risk-based approach to evaluating wildlife demographics for management in a changing climate: A case study of the Lewis's Woodpecker

Given the projected threat that climate change poses to biodiversity, the need for proactive response efforts is clear. However, integrating uncertain climate change information into conservation planning is challenging, and more explicit guidance is needed. To this end, this article provides a specific example of how a risk-based approach can be used to incorporate a species' response to climate into conservation decisions. This is shown by taking advantage of species' response (i.e., impact) models that have been developed for a well-studied bird species of conservation concern. Specifically, we examine the current and potential impact of climate on nest survival of the Lewis's Woodpecker ( Melanerpes lewis ) in two different habitats. To address climate uncertainty, climate scenarios are developed by manipulating historical weather observations to create ensembles (i.e., multiple sequences of daily weather) that reflect historical variability and potential climate change. These ensembles allow for a probabilistic evaluation of the risk posed to Lewis's Woodpecker nest survival and are used in two demographic analyses. First, the relative value of each habitat is compared in terms of nest survival, and second, the likelihood of exceeding a critical population threshold is examined. By embedding the analyses in a risk framework, we show how management choices can be made to be commensurate with a defined level of acceptable risk. The results can be used to inform habitat prioritization and are discussed in the context of an economic framework for evaluating trade-offs between management alternatives.

Idaho↗
USGS2012

Climate downscaling effects on predictive ecological models: a case study for threatened and endangered vertebrates in the southeastern United States

High-resolution (downscaled) projections of future climate conditions are critical inputs to a wide variety of ecological and socioeconomic models and are created using numerous different approaches. Here, we conduct a sensitivity analysis of spatial predictions from climate envelope models for threatened and endangered vertebrates in the southeastern United States to determine whether two different downscaling approaches (with and without the use of a regional climate model) affect climate envelope model predictions when all other sources of variation are held constant. We found that prediction maps differed spatially between downscaling approaches and that the variation attributable to downscaling technique was comparable to variation between maps generated using different general circulation models (GCMs). Precipitation variables tended to show greater discrepancies between downscaling techniques than temperature variables, and for one GCM, there was evidence that more poorly resolved precipitation variables contributed relatively more to model uncertainty than more well-resolved variables. Our work suggests that ecological modelers requiring high-resolution climate projections should carefully consider the type of downscaling applied to the climate projections prior to their use in predictive ecological modeling. The uncertainty associated with alternative downscaling methods may rival that of other, more widely appreciated sources of variation, such as the general circulation model or emissions scenario with which future climate projections are created.

Alabama;Florida;Georgia;Mississippi;South Carolina↗
USGS2013

Perception, experience, and indigenous knowledge of climate change and variability: the case of Accra, a sub-Saharan African city

Several recent international assessments have concluded that climate change has the potential to reverse the modest economic gains achieved in many developing countries over the past decade. The phenomenon of climate change threatens to worsen poverty or burden populations with additional hardships, especially in poor societies with weak infrastructure and economic well-being. The importance of the perceptions, experiences, and knowledge of indigenous peoples has gained prominence in discussions of climate change and adaptation in developing countries and among international development organizations. Efforts to evaluate the role of indigenous knowledge in adaptation planning, however, have largely focused on rural people and their agricultural livelihoods. This paper presents the results of a study that examines perceptions, experiences, and indigenous knowledge relating to climate change and variability in three communities of metropolitan Accra, which is the capital of Ghana. The study design is based on a three-part conceptual framework and interview process involving risk mapping, mental models, and individual stressor cognition. Most of the residents interviewed in the three communities of urban Accra attributed climate change to the combination of deforestation and the burning of firewood and rubbish. None of the residents associated climate change with fossil fuel emissions from developed countries. Numerous potential adaptation strategies were suggested by the residents, many of which have been used effectively during past drought and flood events. Results suggest that ethnic residential clustering as well as strong community bonds in metropolitan Accra have allowed various groups and long-settled communities to engage in the sharing and transmission of knowledge of weather patterns and trends. Understanding and building upon indigenous knowledge may enhance the design, acceptance, and implementation of climate change adaptation strategies in Accra and urban regions of other developing nations.

Accra↗
USGS2022

Climate and land change impacts on future managed wetland habitat: A case study from California’s Central Valley

Concept California’s Central Valley provides critical habitat for migratory waterbirds, yet only 10% of naturally occurring wetlands remain. Competition for limited water supplies and climate change will impact the long-term viability of these intensively managed habitats. Objectives Forecast the distribution, abundance, and connectivity of surface water and managed wetland habitats, using 5 spatially explicit (270 m 2 ) climate/land use/water prioritization scenarios. Mapping potential future dynamic flooded habitat used by waterbirds and other wetland-dependent wildlife to inform management decisions. Methods We integrated a climate-driven hydrologic water use model with a spatially explicit land change model, to examine stakeholder-driven scenarios of future land change, climate, and water use and their impacts on future habitat availability. Results Declining water availability is the dominant driver of habitat loss across scenarios. The hot/dry scenarios showed the greatest declines in January flooded area by 2101—an important month for overwintering waterbirds. In contrast, higher water supplies in wet climates drive perennial cropland conversion and loss of potential habitat. Potential flooded cropland declined (25 and 33%) under warmer/wetter climate conditions due to this conversion to perennial crops, exposing habitat vulnerability. Conclusion Climate-driven loss of water availability had a greater impact on flooded habitat availability than land-use change. When combined, climate change and the conversion of potentially flooded cropland to perennial cropland will threaten future waterbird habitat particularly in January, the peak of the migratory bird season, even when habitat restoration goals are met. Stakeholder-informed scenario analysis can identify target areas for potential habitat change, vulnerability, and conservation.

California↗
USGS2021

A bright spot analysis of inland recreational fisheries in the face of climate change: Learning about adaptation from small successes

Inland recreational fisheries have social, economic, and ecological importance worldwide but these fisheries are increasingly challenged by the diverse effects of climate change. Coupled with other anthropogenic stressors, climate change has contributed to declines in freshwater biodiversity of greater severity than those observed across marine or terrestrial taxa. At a macro level, inland fisheries are experiencing declines. There are, however, a number of success stories, or ‘bright spots,’ in inland recreational fisheries management, where innovative approaches are leading to increases in social and ecological well-being in the face of climate change. Cases such as these are important sources of inspiration and learning about adaptation to climate and environmental change. In this article, we analyze 11 examples of such ‘bright spots’ drawn from multiple jurisdictions around the world from which we extracted lessons that might apply to fisheries management challenges beyond the region and context of each case. Collectively, these bright spots highlight adaptive initiatives that allow for recreational fisheries management to mitigate to stressors associated with current and future climate change. Examples identified include community-based restoration projects, collaborative and adaptive approaches to short-term fisheries closures, transdisciplinary large-scale conservation projects, and conservation-minded efforts by individuals and communities. By highlighting examples of ‘small wins’ within inland recreational fisheries management, this review contributes to the idea that a ‘positive future’ for inland recreational fisheries in the face of climate change is possible and highlights potential strategies to adapt to current and future climate scenarios.

Reviews in Fish Biology and Fisheries↗
USGS2008

Regeneration potential of Taxodium distichum swamps and climate change

Seed bank densities respond to factors across local to landscape scales, and therefore, knowledge of these responses may be necessary in forecasting the effects of climate change on the regeneration of species. This study relates the seed bank densities of species of Taxodium distichum swamps to local water regime and regional climate factors at five latitudes across the Mississippi River Alluvial Valley from southern Illinois to Louisiana. In an outdoor nursery setting, the seed banks of twenty-five swamps were exposed to non-flooded (freely drained) or flooded treatments, and the number and species of seeds germinating were recorded from each swamp during one growing season. Based on ANOVA analysis, the majority of dominant species had a higher rate of germination in non-flooded versus flooded treatments. Similarly, an NMS comparison, which considered the local water regime and regional climate of the swamps, found that the species of seeds germinating, almost completely shifted under non-flooded versus flooded treatments. For example, in wetter northern swamps, seeds of Taxodium distichum germinated in non-flooded conditions, but did not germinate from the same seed banks in flooded conditions. In wetter southern swamps, seeds of Eleocharis cellulosa germinated in flooded conditions, but did not germinate in non-flooded conditions. The strong relationship of seed germination and density relationships with local water regime and regional climate variables suggests that the forecasting of climate change effects on swamps and other wetlands needs to consider a variety of interrelated variables to make adequate projections of the regeneration responses of species to climate change. Because regeneration is an important aspect of species maintenance and restoration, climate drying could influence the species distribution of these swamps in the future. ?? 2008 Springer Science+Business Media B.V.

Plant Ecology↗
USGS2022

Climate refugia for Pinus spp. in topographic and bioclimatic environments of the Madrean sky islands of México and the United States

Climate refugia, or places where habitats are expected to remain relatively buffered from regional climate extremes, provide an important focus for science and conservation planning. Within high-priority, multi-jurisdictional landscapes like the Madrean sky islands of the United States and México, efforts to identify and manage climate refugia are hindered by the lack of high-quality and consistent transboundary datasets. To fill these data gaps, we assembled a bi-national field dataset ( n = 1416) for five pine species ( Pinus spp.) and used generalized boosted regression to model pine habitats in relation to topographic variability as a basis for identifying potential microrefugia at local scales in the context of current species’ distribution patterns. We developed additional models to quantify climatic refugial attributes using coarse scale bioclimatic variables and finer scale seasonal remote sensing indices. Terrain metrics including ruggedness, slope position, and aspect defined microrefugia for pines within elevation ranges preferred by each species. Response to bioclimatic variables indicated that small shifts in climate were important to some species (e.g., P. chihuahuana, P. strobiformis ), but others exhibited a broader tolerance (e.g., P. arizonica ). Response to seasonal climate was particularly important in modeling microrefugia for species with open canopy structure and where regular fires occur (e.g., P. engelmannii and P. chihuahuana ). Hotspots of microrefugia differed among species and were either limited to northern islands or occurred across central or southern latitudes. Mapping and validation of refugia and their ecological functions are necessary steps in developing regional conservation strategies that cross jurisdictional boundaries. A salient application will be incorporation of climate refugia in management of fire to restore and maintain pine ecology.

Arizona, Chihuahua, New Mexico, Sonora↗
USGS2015

Biological response to climate change in the Arctic Ocean: The view from the past

The Arctic Ocean is undergoing rapid climatic changes including higher ocean temperatures, reduced sea ice, glacier and Greenland Ice Sheet melting, greater marine productivity, and altered carbon cycling. Until recently, the relationship between climate and Arctic biological systems was poorly known, but this has changed substantially as advances in paleoclimatology, micropaleontology, vertebrate paleontology, and molecular genetics show that Arctic ecosystem history reflects global and regional climatic changes over all timescales and climate states (10 3 –10 7 years). Arctic climatic extremes include 25°C hyperthermal periods during the Paleocene-Eocene (56–46 million years ago, Ma), Quaternary glacial periods when thick ice shelves and sea ice cover rendered the Arctic Ocean nearly uninhabitable, seasonally sea-ice-free interglacials and abrupt climate reversals. Climate-driven biological impacts included large changes in species diversity, primary productivity, species’ geographic range shifts into and out of the Arctic, community restructuring, and possible hybridization, but evidence is not sufficient to determine whether or when major episodes of extinction occurred.

arktos↗
USGS2012

Climate change and human health: Spatial modeling of water availability, malnutrition, and livelihoods in Mali, Africa

This study develops a novel approach for projecting climate trends in the Sahel in relation to shifting livelihood zones and health outcomes. Focusing on Mali, we explore baseline relationships between temperature, precipitation, livelihood, and malnutrition in 407 Demographic and Health Survey (DHS) clusters with a total of 14,238 children, resulting in a thorough spatial analysis of coupled climate-health dynamics. Results suggest links between livelihoods and each measure of malnutrition, as well as a link between climate and stunting. A ‘front-line’ of vulnerability, related to the transition between agricultural and pastoral livelihoods, is identified as an area where mitigation efforts might be usefully targeted. Additionally, climate is projected to 2025 for the Sahel, and demographic trends are introduced to explore how the intersection of climate and demographics may shift the vulnerability ‘front-line’, potentially exposing an additional 6 million people in Mali, up to a million of them children, to heightened risk of malnutrition from climate and livelihood changes. Results indicate that, holding constant morbidity levels, approximately one quarter of a million children will suffer stunting, nearly two hundred thousand will be malnourished, and over one hundred thousand will become anemic in this expanding arid zone by 2025. Climate and health research conducted at finer spatial scales and within shorter projected time lines can identify vulnerability hot spots that are of the highest priority for adaptation interventions; such an analysis can also identify areas with similar characteristics that may be at heightened risk. Such meso-scale coupled human-environment research may facilitate appropriate policy interventions strategically located beyond today’s vulnerability front-line.

Applied Geography↗
USGS2017

Comparison of climate envelope models developed using expert-selected variables versus statistical selection

Climate envelope models are widely used to describe potential future distribution of species under different climate change scenarios. It is broadly recognized that there are both strengths and limitations to using climate envelope models and that outcomes are sensitive to initial assumptions, inputs, and modeling methods Selection of predictor variables, a central step in modeling, is one of the areas where different techniques can yield varying results. Selection of climate variables to use as predictors is often done using statistical approaches that develop correlations between occurrences and climate data. These approaches have received criticism in that they rely on the statistical properties of the data rather than directly incorporating biological information about species responses to temperature and precipitation. We evaluated and compared models and prediction maps for 15 threatened or endangered species in Florida based on two variable selection techniques: expert opinion and a statistical method. We compared model performance between these two approaches for contemporary predictions, and the spatial correlation, spatial overlap and area predicted for contemporary and future climate predictions. In general, experts identified more variables as being important than the statistical method and there was low overlap in the variable sets (<40%) between the two methods Despite these differences in variable sets (expert versus statistical), models had high performance metrics (>0.9 for area under the curve (AUC) and >0.7 for true skill statistic (TSS). Spatial overlap, which compares the spatial configuration between maps constructed using the different variable selection techniques, was only moderate overall (about 60%), with a great deal of variability across species. Difference in spatial overlap was even greater under future climate projections, indicating additional divergence of model outputs from different variable selection techniques. Our work is in agreement with other studies which have found that for broad-scale species distribution modeling, using statistical methods of variable selection is a useful first step, especially when there is a need to model a large number of species or expert knowledge of the species is limited. Expert input can then be used to refine models that seem unrealistic or for species that experts believe are particularly sensitive to change. It also emphasizes the importance of using multiple models to reduce uncertainty and improve map outputs for conservation planning. Where outputs overlap or show the same direction of change there is greater certainty in the predictions. Areas of disagreement can be used for learning by asking why the models do not agree, and may highlight areas where additional on-the-ground data collection could improve the models.

Ecological Modelling↗
USGS2023

Investigating effects of climate-induced changes in water temperature and diet on mercury concentrations in an Arctic freshwater forage fish

The amount of mercury (Hg) in Arctic lake food webs is, and will continue to be, affected by rapid, ongoing climate change. At warmer temperatures, fish require more energy to sustain growth; changes in their metabolic rates and consuming prey with potentially higher Hg concentrations could result in increased Hg accumulation. To examine the potential implications of climate warming on forage fish Hg accumulation in Arctic lakes, we quantified growth and Hg accumulation in Ninespine Stickleback Pungitius pungitius under different temperature and diet scenarios using bioenergetics models. Four scenarios were considered that examined the role of climate, diet, climate × diet, and climate × diet × elevated prey Hg. As expected, annual fish growth increased with warmer temperatures, but growth rates and Hg accumulation were largely diet dependent. Compared to current growth rates of 0.3 g⋅y −1 , fish growth increased at least 200% for fish consuming energy-dense benthic prey and decreased at least 40% for fish consuming pelagic prey. Compared to baseline levels, the Hg burden per kilocalorie of Ninespine Stickleback declined up to 43% with benthic consumption – indicating strong somatic growth dilution – but no more than 4% with pelagic consumption; elevated prey Hg concentrations led to moderate Hg declines in benthic-foraging fish and Hg increases in pelagic-foraging fish. Bioenergetics models demonstrated the complex interaction of water temperature, growth, prey proportions, and prey Hg concentrations that respond to climate change. Further work is needed to resolve mechanisms and rates linking climate change to Hg availability and uptake in Arctic freshwater systems.

Alaska↗
USGS2022

Climate matching with the climatchR R package

Climate matching allows comparisons of climatic conditions between different locations to understand location and species range climatic suitability. The approach may be used as part of horizon scanning exercises such as those conducted for invasive species. We implemented the CLIMATCH algorithm into an R package, climatchR . The package allows automated and scripted climate matching exercises across all steps from downloading data to summarizing species climate matches. We also show how climatchR may be used with high-throughput computing to process many species. For example, we were able to calculate climate scores for over 8,000 species in less than 3 days using this package. This automation allows high-throughput processing of species data, a new development for improving the efficiency and speed of climate matching and horizon scanning.

Environmental Software & Modeling↗
USGS2025

Mountain sentinels in a changing world: Review and conservation implications of weather and climate effects on mountain goats (Oreamnos americanus)

Climate change is occurring at an accelerated rate in high-elevation alpine and mountain ecosystems. Cold-adapted, mountain species are at risk due to forecasted change and knowledge is needed to respond to current and future conservation challenges. Mountain goats ( Oreamnos americanus ) are an iconic species of North American mountain cultures and landscapes, and due to specialized adaptations for life in cold, mountainous environments they are particularly sensitive to changes in weather and climate. As sentinels of change in alpine ecosystems, the study of mountain goats offers insight into the ecological effects and conservation challenges associated with climate change in these sensitive and biodiverse environments. Here, we synthesize existing knowledge about how climate change is expected to influence environmental conditions experienced by mountain goats and associated mechanistic changes to behavior, nutritional ecology, demography, health, and interspecific interactions. In many instances, climate change effects are likely to be negative and additive to existing threats (such as human disturbance, hunting, disease, predation) though benefits are expected in some cases. Changes in climate and mountain environments will necessitate re-examination and modification of population monitoring, management, and conservation strategies. Specifically, spatiotemporal (and other) aspects of monitoring and management may need to be adjusted to accommodate emerging and novel conservation challenges. Yet, key data and knowledge gaps remain and should be addressed to advance conservation and decision-making capabilities. For mountain goats and similarly climate-sensitive alpine herbivores, effective conservation will ultimately benefit from collaborations among diverse networks guided by well-planned, strategic visions focused on common ground – namely the resiliency and persistence of culturally and ecologically significant mountain species and the alpine environment they inhabit.

Alaska, Alberta, British Columbia, Idaho, Montana,↗
USGS2012

Effects of future climate change, CO 2 enrichment, and vegetation structure variation on hydrological processes in China

Investigating the relationship between factors (climate change, atmospheric CO 2 concentrations enrichment, and vegetation structure) and hydrological processes is important for understanding and predicting the interaction between the hydrosphere and biosphere. The Integrated Biosphere Simulator (IBIS) was used to evaluate the effects of climate change, rising CO 2 , and vegetation structure on hydrological processes in China at the end of the 21st century. Seven simulations were implemented using the assemblage of the IPCC climate and CO 2 concentration scenarios, SRES A2 and SRES B1. Analysis results suggest that (1) climate change will have increasing effects on runoff, evapotranspiration (ET), transpiration (T), and transpiration ratio (transpiration/evapotranspiration, T/E) in most hydrological regions of China except in the southernmost regions; (2) elevated CO 2 concentrations will have increasing effects on runoff at the national scale, but at the hydrological region scale, the physiology effects induced by elevated CO 2 concentration will depend on the vegetation types, climate conditions, and geographical background information with noticeable decreasing effects shown in the arid Inland region of China; (3) leaf area index (LAI) compensation effect and stomatal closure effect are the dominant factors on runoff in the arid Inland region and southern moist hydrological regions, respectively; (4) the magnitudes of climate change (especially the changing precipitation pattern) effects on the water cycle are much larger than those of the elevated CO 2 concentration effects; however, increasing CO 2 concentration will be one of the most important modifiers to the water cycle; (5) the water resource condition will be improved in northern China but depressed in southernmost China under the IPCC climate change scenarios, SRES A2 and SRES B1.

Global and Planetary Change↗