首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 171 毫秒
1.
The Great Lakes Environmental Research Laboratory has developed conceptual daily models for simulating moisture storages in and runoff from the 121 watersheds draining into the Laurentian Great Lakes, over-lake precipitation into each lake, and the heat storages in and evaporation from each lake. We combine these components as net basin supplies for each lake to consider climate change scenarios developed from atmospheric general circulation models (GCMs). Recent scenarios of a doubling of atmospheric Co2, available from the Goddard Institute for Space Studies, the Geophysical Fluid Dynamics Laboratory, and Oregon State University are considered by making changes in historical meteorological data similar to the changes observed in the GCMs, observing the impact of the changed data in the model outputs, and comparing outputs to model results using unchanged data, representing comparison to an unchanged atmosphere. This study indicates a 23 to 51% reduction in net basin supplies to all the Great Lakes; there is significant variation in the components of these supplies among the three GCMs. The basins various moisture storages become dryer and the lakes are warmer with associated hydrological impacts.GLERL Contribution NO. 646.  相似文献   

2.
This modeling study addresses the potential impacts of climate change and changing climate variability due to increased atmospheric CO2 concentration on soybean (Glycine max (L.) Merrill) yields in theMidwestern Great Lakes Region. Nine representative farm locations and six future climate scenarios were analyzed using the crop growth model SOYGRO. Under the future climate scenarios earlierplanting dates produced soybean yield increases of up to 120% above current levels in the central and northern areas of the study region. In the southern areas, comparatively small increases (0.1 to 20%) and small decreases (–0.1 to–25%) in yield are found. The decreases in yield occurred under the Hadley Center greenhouse gas run (HadCM2-GHG), representing a greater warming, and the doubled climate variability scenario – a more extreme and variableclimate. Optimum planting dates become later in the southern regions. CO2fertilization effects (555 ppmv) are found to be significant for soybean, increasing yields around 20% under future climate scenarios.For the study region as a whole the climate changes modeled in this research would have an overall beneficial effect, with mean soybean yield increases of 40% over current levels.  相似文献   

3.
Hydrological models of the Great Lakes basin were used to study the sensitivity of Great Lakes water supplies to climate warming by driving them with meteorological data from four U.S. climate zones that were transposed to the basin. Widely different existing climates were selected for transposition in order to identify thresholds of change where major impacts on water supplies begin to occur and whether there are non-linear responses in the system. The climate zones each consist of 43 years of daily temperature and precipitation data for 1,000 or more stations and daily evaporation-related variables (temperature, wind speed, humidity, cloud cover) for approximately 20–35 stations. A key characteristic of these selected climates was much larger variability in inter-annual precipitation than currently experienced over the Great Lakes. Climate data were adjusted to simulate lake effects; however, a comparison of hydrologic results with and without lake effects showed that there was only minor effects on water supplies.  相似文献   

4.
Statistical ice cover models were used to project daily mean basin ice cover and annual ice cover duration for Lakes Superior and Erie. Models were applied to a 1951–80 base period and to three 30-year steady double carbon dioxide (2 × CO2) scenarios produced by the Geophysical Fluid Dynamics Laboratory (GFDL), the Goddard Institute of Space Studies (GISS), and the Oregon State University (OSU) general circulation models. Ice cover estimates were made for the West, Central, and East Basins of Lake Erie and for the West, East, and Whitefish Bay Basins of Lake Superior. Average ice cover duration for the 1951– 80 base period ranged from 13 to 16 weeks for individual lake basins. Reductions in average ice cover duration under the three 2 × CO2 scenarios for individual lake basins ranged from 5 to 12 weeks for the OSU scenario, 8 to 13 weeks for the GISS scenario, and 11 to 13 weeks for GFDL scenario. Winters without ice formation become common for Lake Superior under the GFDL scenario and under all three 2 × CO2 scenarios for the Central and East Basins of Lake Erie. During an average 2 × CO2 winter, ice cover would be limited to the shallow areas of Lakes Erie and Superior. Because of uncertainties in the ice cover models, the results given here represent only a first approximation and are likely to represent an upper limit of the extent and duration of ice cover under the climate change projected by the three 2 × CO2scenarios. Notwithstanding these limitations, ice cover projected by the 2 × CO2 scenarios provides a preliminary assessment of the potential sensitivity of the Great Lakes ice cover to global warming. Potential environmental and socioeconomic impacts of a 2 × CO2 warming include year-round navigation, change in abundance of some fish species in the Great Lakes, discontinuation or reduction of winter recreational activities, and an increase in winter lake evaporation.  相似文献   

5.
During this century global warming will lead to changes in global weather and climate, affecting many aspects of our environment. Agriculture is the sector of the United States economy most likely to be directly impacted by climatic changes. We have examined potential changes in dryland agriculture (Part 3) and in water resources necessary for crop production (Part 4) in response to a set of climate change scenarios. In this paper we assess to what extent, under these same scenarios, water supplies will be sufficient to meet the irrigation requirement of major grain crops in the US. In addition, we assess the overall impacts of changes in water supply on national grain production. We apply the 12 climate change scenarios described in Part 1 to the water resources and crop growth simulation models described in Part 2 for the conterminous United States. Drawing on data from Parts 3 and 4 we calculate what the aggregate national production would be in those regions in which grain crops are currently produced by applying irrigation where needed and water supplies allow. The total amount of irrigation water applied to crops declines under all climate change scenarios employed in this study. Under certain of the scenarios and in particular regions, precipitation decreases so much that water supplies are too limited; in other regions precipitation becomes so plentiful that little value is derived from irrigation. Nationwide grain crop production is greater when irrigation is applied as needed. Under irrigation, less corn and soybeans are produced under most of the climate change scenarios than is produced under baseline climate conditions. Winter wheat production under irrigation responds significantly to elevated atmospheric carbon dioxide concentrations [CO2] and appears likely to increase under climate change.  相似文献   

6.
Summary  It is expected that a change in climatic conditions due to global warming will directly impact agricultural production. Most climate change studies have been applied at very large scales, in which regions were represented by only one or two weather stations, which were mainly located at airports of major cities. The objective of this study was to determine the potential impact of climate change at a local level, taking into account weather data recorded at remote locations. Daily weather data for a 30-year period were obtained for more than 500 sites, representing the southeastern region of the USA. Climate change scenarios, using transient and equilibrium global circulation models (GCM), were defined, created and applied to the daily historical weather data. The modified temperature, precipitation and solar radiation databases corresponding to each of the climate change scenarios were used to run the CERES v.3.5 simulation model for maize and winter wheat and the CROPGRO v.3.5 model for soybean and peanut. The GCM scenarios projected a shorter duration of the crop-growing season. Under the current level of CO2, the GCM scenarios projected a decrease of crop yields in the 2020s. When the direct effects of CO2 were assumed in the study, the scenarios resulted in an increase in soybean and peanut yield. Under equilibrium , the GCM climate change scenarios projected a decrease of maize and winter wheat yield. The indirect effects of climate change also tended to decrease soybean and peanut yield. However, when the direct effects of CO2 were included, most of the scenarios resulted in an increase in legume yields. Possible changes in sowing data, hybrids and cultivar selection, and fertilization were considered as adaptation options to mitigate the potential negative impact of potential warming. Received July 20, 1999/Revised April 18, 2000  相似文献   

7.
Paleo-reconstructed hydrologic records offer the potential to evaluate water resources system performance under conditions that may be more extreme than seen in the historical record. This study uses a stochastic simulation framework consisting of a non-homogeneous Markov chain model (NHMM) to simulate the climate state using Palmer Drought Severity Index (PDSI)-reconstructed data, and K-nearest neighbor (K-NN) to resample observational net basin supply magnitudes for the Great Lakes of North America. The method was applied to generate 500 plausible simulations, each with 100 years of monthly net basin supply for the Upper Great Lakes, to place the observed data into a longer temporal context. The range of net basin supply sequences represents what may have occurred in the past 1,000 years and which can occur in future. The approach was used in evaluation of operational plans for regulation of Lake Superior outflows with implications for lake levels of Superior, Michigan, Huron and Erie, and their interconnecting rivers. The simulations generally preserved the statistics of the observed record while providing new variability statistics. The framework produced a variety of high and low net basin supply sequences that provide a broader estimate of the likelihood of extreme lake levels and their persistence than with the historical record. The method does not rely on parametrically generated net basin supply values unlike parametric stochastic simulation techniques, yet still generates new variability through the incorporation of the paleo-record. The process described here generated new scenarios that are plausible based on the paleo and historic record. The evaluation of Upper Great Lakes regulation plans, subject to these scenarios, was used to evaluate robustness of the regulation plans. While the uncertain future climate cannot be predicted, one can evaluate system performance on a wide range of plausible climate scenarios.  相似文献   

8.
Frank Millerd 《Climatic change》2011,104(3-4):629-652
The higher temperatures of climate change may result in a fall in Great Lakes water levels. For vessels carrying imports into and exports out of the Great Lakes lower lake levels will lead to restrictions on vessel drafts and reductions in vessel cargos, increasing the number of trips and the cost of moving cargo. Estimates of these impacts are derived from simulations of a recent year??s international cargo movements, comparing a base case with no climate change to various climate change scenarios. The impacts vary from a 5% increase in vessel variable operating costs for a climate change scenario representing the possible climate in 2030 to over 22% for a scenario representing a doubling of atmospheric carbon dioxide. Impacts vary by commodity and route. For years of naturally occurring low water the impacts are up to 13% higher for even the most moderate climate change scenario. Climate change may also result in a shorter time of ice cover leading to an extension of the navigation season. Climate change is also expected to increase the threat of damage from aquatic invasive species, possibly leading to further requirements for ships to undertake preventive measures.  相似文献   

9.
This paper represents an attempt to combine the output of several models that deal with future climatic, hydrologic and economic conditions in the Great Lakes and makes some predictions about the possible impact of one scenario of 2 × CO2 climate on Great Lakes shipping. It is realized that there is a great deal of uncertainty in all the models and that improvements are continually being made. Data from a General Circulation Model of future temperature and precipitation in the Great Lakes basin, a Great Lakes levels and flows model from the Canada Centre for Inland Waters and an International Joint Commision's Great Lakes economic model modified by the University of Wisconsin were used. The 1900–1976 period of lake levels and flows was used. The hydrologic model indicated that future mean lake levels may be reduced by one-half meter, and that the extreme low levels of the mid 1960's could occur 77% of the time in the future. No ice cover is predicted for any lake except Erie, permitting an eleven month shipping season. Five scenarios of future impact on shipping were evaluated. It was found that mean annual shipping costs may increase by 30% and the frequency of years when costs exceed those of the period of low lake levels (1963–65) could rise to 97%. Possible policy options in a future with climatically induced lower lake levels could include regulation to keep levels artificially high by diversions into the system, or increased dredging of the connecting channels.  相似文献   

10.
The impacts of the climate change predictions of four general circulation models (GFDL, GISS, OSU and UKMO) on net primary production (NPP) ofBetula pubescens, Fagus sylvatica and Quercus robur in The Netherlands were analysed using the process-based model FORGRO. FORGRO is a model suitable to simulate growth of managed mono-species stands. For the GCMs mentioned, both transient and equilibrium 2 × CO2 scenarios of temperature and precipitation change were evaluated and compared with responses under current climate. It was found that the NPP increases in the transient scenarios, but remains the same or declines in the 2 × CO2 scenarios. This is because respiration increases more with rising temperature than photosynthesis. During the transient scenarios this effect gradually increases, while in the 2 × CO2 scenario this effect is operating over the entire simulation period.If water limitation is taken into account, then the NPP of the reference scenario is reduced. In both the transient and 2 × CO2 scenarios mis water limitation is annulated, resulting in a stronger response of NPP compared to the situation without water limitation. This enhancement of the response is most pronounced in the transient scenario due to the gradual effect of temperature on respiration.Similar results were obtained with a version of FORGRO in which the photosynthesis module of HYBRID (PGEN) is incorporated, although the response in FORGRO-PGEN is usually higher than that of FORGRO. This is because the response of photosynthesis to CO2 rises with increasing temperature as defined in the PGEN-model, but not according to FORGRO.  相似文献   

11.
Scenarios of CO2-induced climatic change, based on models produced by the Goddard Institute for Space Studies (GISS) and the Geophysical Fluid Dynamics Lab (GFDL), were used to estimate future changes in water supply in the Great Lakes Basin. The major components of annual Net Basin Supply, surface runoff and lake evaporation, were estimated using the Thornthwaite water balance model and the mass transfer approach, respectively. Two scenarios were derived from each climatic change model, one based on present normal winds, the other assuming reduced wind speeds. A third scenario was derived from GFDL, using wind speeds generated by the GFDL model. Results varied from a decrease in Net Basin Supply of 28.9% for GISS-normal winds, to a decrease of 11.7% for GFDL-reduced wind speeds. All five scenarios projected decreases. These differences in projection will have to be considered when performing climate impact studies, since economic activities affected by lake levels would probably experience different impacts under these scenarios.  相似文献   

12.
Effect of climate change on watershed system: a regional analysis   总被引：1，自引：0，他引：1  
Climate-induced increase in surface temperatures can impact hydrologic processes of a watershed system. This study uses a continuous simulation model to evaluate potential implications of increasing temperature on water quantity and quality at a regional scale in the Connecticut River Watershed of New England. The increase in temperature was modeled using Intergovernmental Panel on Climate Change (IPCC) high and low warming scenarios to incorporate the range of possible temperature change. It was predicted that climate change can have a significant affects on streamflow, sediment loading, and nutrient (nitrogen and phosphorus) loading in a watershed. Climate change also influences the timing and magnitude of runoff and sediment yield. Changes in variability of flows and pollutant loading that are induced by climate change have important implications on water supplies, water quality, and aquatic ecosystems of a watershed. Potential impacts of these changes include deficit supplies during peak seasons of water demand, increased eutrophication potential, and impacts on fish migration.  相似文献   

13.
The North American Laurentian Great Lakes hold nearly 20 % of the earth’s unfrozen fresh surface water and have a length of coastline, and a coastal population, comparable to frequently-studied marine coasts. The surface water elevations of the Great Lakes, in particular, are an ideal metric for understanding impacts of climate change on large hydrologic systems, and for assessing adaption measures for absorbing those impacts. In light of the importance of the Great Lakes to the North American and global economies, the Great Lakes and the surrounding region also serve as an important benchmark for hydroclimate research, and offer an example of successful adaptive management under changing climate conditions. Here, we communicate some of the important lessons to be learned from the Great Lakes by examining how the coastline, water level, and water budget dynamics of the Great Lakes relate to other large coastal systems, along with implications for water resource management strategies and climate scenario-derived projections of future conditions. This improved understanding fills a critical gap in freshwater and marine global coastal research.  相似文献   

14.
Food production in China is a fundamental component of the national economy and driver of agricultural policy. Sustaining and increasing output to meet growing demand faces significant challenges including climate change, increasing population, agricultural land loss and competing demands for water. Recent warming in China is projected to accelerate by climate models with associated changes in precipitation and frequency of extreme events. How changes in cereal production and water availability due to climate change will interact with other socio-economic pressures is poorly understood. By linking crop and water simulation models and two scenarios of climate (derived from the Regional Climate Model PRECIS) and socio-economic change (downscaled from IPCC SRES A2 and B2) we demonstrate that by the 2040s the absolute effects of climate change are relatively modest. The interactive effects of other drivers are negative, leading to decreases in total production of ?18% (A2) and ?9% (B2). Outcomes are highly dependent on climate scenario, socio-economic development pathway and the effects of CO2 fertilization on crop yields which may almost totally offset the decreases in production. We find that water availability plays a significant limiting role on future cereal production, due to the combined effects of higher crop water requirements (due to climate change) and increasing demand for non-agricultural use of water (due to socio-economic development). Without adaptation, per capita cereal production falls in all cases, by up to 40% of the current baseline.By simulating the effects of three adaptation scenarios we show that for these future scenarios China is able to maintain per capita cereal production, given reasonable assumptions about policies on land and water management and progress in agricultural technology. Our results are optimistic because PRECIS simulates much wetter conditions than a multi-model average, the CO2 crop yield response function is highly uncertain and the effects of extreme events on crop growth and water availability are likely to be underestimated.  相似文献   

15.
Regional climate modelling represents an appealing approach to projecting Great Lakes water supplies under a changing climate. In this study, we investigate the response of the Great Lakes Basin to increasing greenhouse gas and aerosols emissions using an ensemble of sixteen climate change simulations generated by three different Regional Climate Models (RCMs): CRCM4, HadRM3 and WRFG. Annual and monthly means of simulated hydro-meteorological variables that affect Great Lakes levels are first compared to observation-based estimates. The climate change signal is then assessed by computing differences between simulated future (2041–2070) and present (1971–1999) climates. Finally, an analysis of the annual minima and maxima of the Net Basin Supply (NBS), derived from the simulated NBS components, is conducted using Generalized Extreme Value distribution. Results reveal notable model differences in simulated water budget components throughout the year, especially for the lake evaporation component. These differences are reflected in the resulting NBS. Although uncertainties in observation-based estimates are quite large, our analysis indicates that all three RCMs tend to underestimate NBS in late summer and fall, which is related to biases in simulated runoff, lake evaporation, and over-lake precipitation. The climate change signal derived from the total ensemble mean indicates no change in future mean annual NBS. However, our analysis suggests an amplification of the NBS annual cycle and an intensification of the annual NBS minima in future climate. This emphasizes the need for an adaptive management of water to minimize potential negative implications associated with more severe and frequent NBS minima.  相似文献   

16.
Great Lakes Hydrology Under Transposed Climates   总被引：3，自引：0，他引：3  
Historical climates, based on 43 years of daily data from areas south and southwest of the Great Lakes, were used to examine the hydrological response of the Great Lakes to warmer climates. The Great Lakes Environmental Research Laboratory used their conceptual models for simulating moisture storages in, and runoff from, the 121 watersheds draining into the Great Lakes, over-lake precipitation into each lake, and the heat storages in, and evaporation from, each lake. This transposition of actual climates incorporates natural changes in variability and timing within the existing climate; this is not true for General Circulation Model-generated corrections applied to existing historical data in many other impact studies. The transposed climates lead to higher and more variable over-land evapotranspiration and lower soil moisture and runoff with earlier runoff peaks since the snow pack is reduced up to 100%. Water temperatures increase and peak earlier. Heat resident in the deep lakes increases throughout the year. Buoyancy-driven water column turnover frequency drops and lake evaporation increases and spreads more throughout the annual cycle. The response of runoff to temperature and precipitation changes is coherent among the lakes and varies quasi-linearly over a wide range of temperature changes, some well beyond the range of current GCM predictions for doubled CO2 conditions.  相似文献   

17.
Assessing the Impact of Climate Change on the Great Lakes Shoreline Wetlands   总被引：12，自引：1，他引：11  
Great Lakes shoreline wetlands are adapted to a variable water supply. They require the disturbance of water level fluctuations to maintain their productivity. However, the magnitude and rate of climate change could alter the hydrology of the Great Lakes and affect wetland ecosystems. Wetlands would have to adjust to a new pattern of water level fluctuations; the timing, duration, and range of these fluctuations are critical to the wetland ecosystem response. Two "what if" scenarios: (1) an increased frequency and duration of low water levels and (2) a changed temporal distribution and amplitude of seasonal water levels were developed to assess the sensitivity of shoreline wetlands to climate change. Wetland functions and values such as wildlife, waterfowl and fish habitat, water quality, areal extent, and vegetation diversity are affected by these scenarios. Key wetlands are at risk, particularly those that are impeded from adapting to the new water level conditions by man-made structures or geomorphic conditions. Wetland remediation, protection and enhancement policies and programs must consider climate change as an additional stressor of wetlands.  相似文献   

18.
 Impulse-response-function (IRF) models are designed for applications requiring a large number of climate change simulations, such as multi-scenario climate impact studies or cost-benefit integrated-assessment studies. The models apply linear response theory to reproduce the characteristics of the climate response to external forcing computed with sophisticated state-of-the-art climate models like general circulation models of the physical ocean-atmosphere system and three-dimensional oceanic-plus-terrestrial carbon cycle models. Although highly computer efficient, IRF models are nonetheless capable of reproducing the full set of climate-change information generated by the complex models against which they are calibrated. While limited in principle to the linear response regime (less than about 3 ∘C global-mean temperature change), the applicability of the IRF model presented has been extended into the nonlinear domain through explicit treatment of the climate system's dominant nonlinearities: CO2 chemistry in ocean water, CO2 fertilization of land biota, and sublinear radiative forcing. The resultant nonlinear impulse-response model of the coupled carbon cycle-climate system (NICCS) computes the temporal evolution of spatial patterns of climate change for four climate variables of particular relevance for climate impact studies: near-surface temperature, cloud cover, precipitation, and sea level. The space-time response characteristics of the model are derived from an EOF analysis of a transient 850-year greenhouse warming simulation with the Hamburg atmosphere-ocean general circulation model ECHAM3-LSG and a similar response experiment with the Hamburg carbon cycle model HAMOCC. The model is applied to two long-term CO2 emission scenarios, demonstrating that the use of all currently estimated fossil fuel resources would carry the Earth's climate far beyond the range of climate change for which reliable quantitative predictions are possible today, and that even a freezing of emissions to present-day levels would cause a major global warming in the long term. Received: 28 January 2000 / Accepted: 9 March 2001  相似文献   

19.
A new method is proposed to estimate future net basin supplies and lake levels for the Laurentian Great Lakes based on GCM projections of global climate change. The method first dynamically downscales the GCM simulation with a regional climate model, and then bias—corrects the simulated net basin supply in order to be used directly in a river—routing/lake level scheme. This technique addresses two weaknesses in the traditional approach, whereby observed sequences of climate variables are perturbed with fixed ratios or differences derived directly from GCMs in order to run evaporation and runoff models. Specifically, (1) land surface—atmosphere feedback processes are represented, and (2) changes in variability can be analyzed with the new approach. The method is demonstrated with a single, high resolution simulation, where small changes in future mean lake levels for all the upper Great Lakes are found, and an increase in seasonal range—especially for Lake Superior—is indicated. Analysis of a small ensemble of eight lower resolution regional climate model simulations supports these findings. In addition, a direct comparison with the traditional approach based on the same GCM projections used as the driving simulations in this ensemble shows that the new method indicates smaller declines in level for all the upper Great Lakes than has been reported previously based on the traditional method, though median differences are only a few centimetres in each case.  相似文献   

20.
Climate change will affect the energy system in a number of ways, one of which is through changes in demands for heating and cooling in buildings. Understanding the potential effect of climate change on heating and cooling demands requires taking into account not only the manner in which the building sector might evolve over time, but also important uncertainty about the nature of climate change itself. In this study, we explore the uncertainty in climate change impacts on heating and cooling requirement by constructing estimates of heating and cooling degree days (HDD/CDDs) for both reference (no-policy) and 550 ppmv CO2 concentration pathways built from three different Global Climate Models (GCMs) output and three scenarios of gridded population distribution. The implications that changing climate and population distribution might have for building energy consumption in the U.S. and China are then explored by using the results of HDD/CDDs as inputs to a detailed, building energy model, nested in the long-term global integrated assessment framework, Global Change Assessment Model (GCAM). The results across the modeled changes in climate and population distributions indicate that unabated climate change would cause building sector’s final energy consumption to decrease modestly (6 % decrease or less depending on climate models) in both the U.S. and China by the end of the century as decreased heating consumption more than offsets increased cooling using primarily electricity. However, global climate change virtually has negligible effect on total CO2 emissions in the buildings sector in both countries. The results also indicate more substantial implications for the fuel mix with increases in electricity and decreases in other fuels, which may be consistent with climate mitigation goals. The variation in results across all scenarios due to variation of population distribution is smaller than variation due to the use of different climate models.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号