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1.
Future heat vulnerability in California, Part II: projecting future heat-related mortality 总被引：1，自引：0，他引：1
Scott C. Sheridan Michael J. Allen Cameron C. Lee Laurence S. Kalkstein 《Climatic change》2012,115(2):311-326
Through the 21st century, a significant increase in heat events is likely across California (USA). Beyond any climate change, the state will become more vulnerable through demographic changes resulting in a rapidly aging population. To assess these impacts, future heat-related mortality estimates are derived for nine metropolitan areas in the state for the remainder of the century. Heat-related mortality is first assessed by initially determining historical weather-type mortality relationships for each metropolitan area. These are then projected into the future based on predicted weather types created in Part I. Estimates account for several levels of uncertainty: for each metropolitan area, mortality values are produced for five different climate model-scenarios, three different population projections (along with a constant-population model), and with and without partial acclimatization. Major urban centers could have a greater than tenfold increase in short-term increases in heat-related mortality in the over 65 age group by the 2090s. 相似文献
2.
山西地处气候过渡带,气候敏感、生态脆弱,在全球气候变暖背景下其陆面物理过程受气候波动影响十分明显。本文利用NCAR CCSM IPCC AR4陆面分量模式(CLM)20世纪气候模拟(20C3M)和21世纪SRES A1B排放情景下的模拟结果,对山西省21世纪(2001~2099年)与20世纪(1901~1999年)陆面能量和水文变量进行了对比分析。结果显示:(1)模式模拟出山西地区未来地面温度的空间及时间分布特征。未来山西省地面温度呈明显上升趋势,上升速率冬季大于夏季。空间上,增温幅度冬季自北向南递减,夏季自西向东递减;(2)未来山西省陆面各分量空间上,净辐射通量西北增幅大于东南,降水率和径流率则与其相反,潜热通量与蒸发率一致,西南部增加幅度大,土壤含水率冬夏分布相反,感热通量呈下降趋势,西南下降幅度大;时间上,净辐射通量、潜热通量均表现出不同程度的上升趋势,土壤热通量冬季上升,夏季下降;地表水循环的各分量均呈增加趋势。 相似文献
3.
Climate change that results from increasing levels of greenhouse gases in the atmosphere has the potential to increase temperature and alter rainfall patterns across the boreal forest region of Canada. Daily output from the Canadian Climate Centre coupled general circulation model (GCM) and the Hadley Centre's HadCM3 GCM provided simulated historic climate data and future climate scenarios for the forested area of the province of Ontario, Canada. These models project that in climates of increased greenhouse gases and aerosols, surface air temperatures will increase while seasonal precipitation amounts will remain relatively constant or increase slightly during the forest fire season. These projected changes in weather conditions are used to predict changes in the moisture content of forest fuel, which influences the incidence of people-caused forest fires. Poisson regression analysis methods are used to develop predictive models for the daily number of fires occurring in each of the ecoregions across the forest fire management region of Ontario. This people-caused fire prediction model, combined with GCM data, predicts the total number of people-caused fires in Ontario could increase by approximately 18% by 2020–2040 and50% by the end of the 21st century. 相似文献
4.
中国20年一遇气温和降水极值变化的高分辨率模拟 总被引：1，自引：0，他引：1
基于25 km高分辨率区域气候模式（RegCM3）嵌套MIROC3.2_hires全球气候模式结果,进行IPCC SRES A1B情景下21世纪气候变化的模拟,分析中国区域未来气温和降水极值重现期的变化。首先检验模式对当代（1981-2000年）极端事件重现期的模拟能力,结果表明,模式能够较好地再现中国地区20年一遇极端事件的基本分布型,但所模拟的数值与观测相比还有一定偏差,特别是在极端降水方面。21世纪中期（2041-2060年）和末期（2081-2100年）20年一遇的高温极值在整个区域内均将升高,东北地区增幅最大;低温极值将增大,中心位于内蒙古、新疆及青藏高原南麓;降水极值也将普遍增大。气温和降水极值在21世纪末期的增加幅度均比中期要大。在未来全球变暖背景下,中国地区极端高温事件将明显增多,面积增大;极端低温事件将大幅度减少,面积减少;强降水事件也将增多,面积不断扩大。 相似文献
5.
中国的气候变化与全球变化有相当的一致性，但也存在明显差别。在全球变暖背景下，近100 a来中国年平均地表气温明显增加，升温幅度比同期全球平均值略高。近100 a和近50 a的降水量变化趋势不明显，但1956年以来出现了微弱增加的趋势。近50 a来中国主要极端天气气候事件的频率和强度也出现了明显的变化。研究表明，中国的CO2年排放量呈不断增加趋势，温室气体正辐射强迫的总和是造成气候变暖的主要原因。对21世纪气候变化趋势做出的预测表明：未来20～100 a，中国地表气温增加明显，降水量也呈增加趋势。 相似文献
6.
K. D. Hage 《大气与海洋》2013,51(1):8-14
The methods used in an earlier study focusing on the province of Ontario, Canada, were adapted for this current study to expand the study area over eastern Canada where the infrastructure is at risk of being impacted by freezing rain. To estimate possible impacts of climate change on future freezing rain events, a three-step process was used in the study: (1) statistical downscaling, (2) synoptic weather typing, and (3) future projections. A regression-based downscaling approach, constructed using different regression methods for different meteorological variables, was used to downscale the outputs of eight general circulation models to each of 42 hourly observing stations over eastern Canada. Using synoptic weather typing (principal components analysis, a clustering procedure, discriminant function analysis), the freezing rain-related weather types under historical climate (1958–2007) and future downscaled climate conditions (2016–2035, 2046–2065, 2081–2100) were identified for all selected stations. The potential changes in the frequency of future daily freezing rain events can be projected quantitatively by comparing future and historical frequencies of freezing rain-related weather types. The modelled results show that eastern Canada could experience more freezing rain events late this century during the coldest months (i.e., December to February) than the averaged historical conditions. Conversely, during the warmest months of the study season (i.e., November and April in the southern regions, October in the northern regions), eastern Canada could experience less freezing rain events late this century. The increase in the number of daily freezing rain events in the future for the coldest months is projected to be progressively greater from south to north or from southwest to northeast across eastern Canada. The relative decrease in magnitude of future daily freezing rain events in the warmest months is projected to be much less than the relative increase in magnitude in the coldest months. 相似文献
7.
Numerical experiments are analyzed for 1860–2100 with the version of the climate model of intermediate complexity of the Obukhov Institute of Atmospheric Physics of the Russian Academy of Sciences (IAP RAS) including the model of general ocean circulation as the oceanic module (CM IAP RAS-GOC) taking account of concentration variations of anthropogenic greenhouse gases and tropospheric sulfate aerosols from the data of observations and reconstructions for the second half of the 19th and for the 20th century and, according to SRES scenarios, in the 21st century. In the 20th century, the model simulates realistically the variations of surface atmospheric temperature, characteristics of heat absorption by the ocean, and oceanic meridional heat transport. The linear trend of global surface atmospheric temperature in the 20th century (in its last 30 years) in this version of the model amounts to 0.5 ± 0.1 K/100 years (0.22 ± 0.05 K/10 years) that is agreed with the observational data. In the 21st century, the global increase in the surface temperature amounts to 2.5 K (3.5 and 4.1 K) for SRES B1 scenario (for SRES A1B and SRES A2 scenarios, respectively). The increase in the surface temperature is the most significant in high latitudes, especially in the Northern Hemisphere and it is higher, on the whole, over the land than over the ocean. The warming near the surface is larger in winter than in summer. The maximum warming is observed in the Arctic and over the land of subpolar latitudes of the Northern Hemisphere reaching 6–10 K by the end of the 21st century in these regions as compared with the end of the 20th century depending on the anthropogenic impact scenario. At the increase in surface temperature in the 20th–21st centuries, the increase in the heat flow to the ocean and the weakening of the heat transport by the ocean from the tropics to the polar area by 1.5–2 times are registered, on the whole. At the warming, the CM IAP RAS-GOC gives the general increase in the annual precipitation amount which is especially appreciable in the tropics and in the storm-track regions. At the global averaging, the precipitation in the 21st century increase by 20–25%. 相似文献
8.
In a warming climate, atmospheric wave activity and associated weather patterns may change, although conflicting results have been reported on this topic. Additionally, atmospheric wave changes in a future climate have mainly focused on waves of a specified spatial scale, rather than a particular spatiotemporal scale. Here, changes in the variability of Rossby waves of multiple spatiotemporal scales are analyzed using the wavenumber-frequency power spectrum, a tool commonly applied to analyze atmospheric equatorial waves. Daily 500 hPa geopotential height data over 40°–60°N from historical (1950–2005) and future (2006–2099) simulations from 20 models in the Coupled Model Intercomparison Project Phase 5 (CMIP5) under the RCP8.5 scenario were analyzed. When compared to the historical period, the late 21st century climate projections showed a decline in spectral power for both eastward and westward propagating waves with wavenumbers greater than 8 that spanned over all frequencies in all seasons, but an increase in mean power for eastward propagating waves with wavenumbers 1–7 over all frequencies was shown in winter and spring. This increase in power was accompanied by increased variance, i.e., an increased meridional extent of 500 hPa ridges and troughs, and was the result of increases in the mean number of high amplitude events and duration of activity within this wave band. These results indicate that large-scale (~ 104 km) eastward propagating weather systems may intensify with higher amplitudes for ridges and troughs, while short-scale (102–103 km) weather systems may decrease in their intensity due to reduced variability in the late 21st century under the high emissions scenario. Potential mechanisms for these changes are discussed, including enhanced Arctic warming and midlatitude-tropical interactions. 相似文献
9.
中国地区IPCC A1B情景下21世纪中期气候变化的数值模拟试验 总被引：5，自引：4，他引：1
利用MM5V3区域气候模式单向嵌套ECHAM5全球环流模式的结果,对中国地区实际温室气体浓度下当代气候(1981—2000年)及IPCC A1B情景下21世纪中期气候(2041—2060年)分别进行了水平分辨率为50 km的模拟试验。首先检验全球和区域模式对当代气候的模拟情况,结果表明:区域模式对中国地区地面温度和降水空间分布的模拟能力优于全球模式;与实际观测相比,区域模式模拟的地面温度在中国大部分地区偏低,模拟的降水量偏多,降水位置偏北。IPCCA1B情景下中国地区21世纪中期气候变化的模式结果显示:各季节地面温度在全国范围内都将比当代升高1.2～3.9℃,且升温幅度具有北方大于南方、冬季大于夏季的时空分布特征;降水变化具有一定的区域性和季节性,秋季和冬季降水在全国大部分地区都将增加10%～30%,春季和夏季降水则呈现"北方减少、南方增多"的趋势,变化幅度在-10%～10%之间。21世纪中期地面温度和降水变化还具有一定的年际特征:地面温度在中国地区各子区域均表现为上升趋势,升温速率在0.7～0.9℃/10a之间,温度变率也比当代有所增大;降水在西北地区略呈下降趋势,在其它子区域均为上升,降水变率的变化具有区域性特征。 相似文献
10.
气候变化国家评估报告(Ⅰ):中国气候变化的历史和未来趋势 总被引：7，自引：0，他引：7
丁一汇 任国玉 石广玉 Gong Peng Zheng Xunhua Zhai Panmao Zhang De'er Zhao Zongci Wang Shaowu Wang Huijun Luo Yong Chen Deliang Gao Xuejie Dai Xiaosu 《气候变化研究进展》2007,3(Z1):1-5
The climate change in China shows a considerable similarity to the global change, though there still exist some significant differences between them. In the context of the global warming, the annual mean surface air temperature in the country as a whole has significantly increased for the past 50 years and 100 years, with the range of temperature increase slightly greater than that in the globe. The change in precipitation trends for the last 50 and 100 years was not significant, but since 1956 it has assumed a weak increasing trend. The frequency and intensity of main extreme weather and climate events have also undergone a significant change. The researches show that the atmospheric CO2 concentration in China has continuously increased and the sum of positive radiative forcings produced by greenhouse gases is probably responsible for the country-wide climate warming for the past 100 years, especially for the past 50 years. The projections of climate change for the 21st century using global and regional climate models indicate that, in the future 20-100 years, the surface air temperature will continue to increase and the annual precipitation also has an increasing trend for most parts of the country. 相似文献
11.
利用CORDEX-EA计划11个区域模式模拟结果,集合预估了中国西部干旱区16个极端温度指数未来的变化趋势及空间分布。结果表明:1)区域模式基本上能够再现近30 a西部干旱区极端温度的空间分布。2)多模式集合预估的西部干旱区21世纪中期霜冻日数(FD)和冰封日数(ID)呈现显著的下降趋势,而热夜日数(TR)和夏季日数(SU)则呈现明显的上升趋势。3)未来异常暖昼持续指数(WSDI)和生长期(GSL)呈现增加趋势,异常冷昼持续指数(CSDI)和日较差(DTR)则呈现下降趋势。4)未来气候增温导致冷昼日数(TX90p)、暖夜日数(TN90p)增加,而暖昼日数(TX10p)和冷夜日数(TN10p)减少。5)未来月最高温度极大值(TXx)、月最低温度极大值(TNx)、月最高温度极小值(TXn)和月最低温度极小值(TNn)都呈现增加的趋势。因此,西部干旱区未来发生极端低温事件的概率减小,发生极端高温事件的概率则会增大,但不同的极端温度指数变化的空间分布并不均一,存在明显的区域差异。 相似文献
12.
大气科学的世纪进展与未来展望 总被引：11，自引：2，他引：9
今天的大气科学已从20世纪初经验的阐述转变为既有理论基础又有客观定量化的一门数理学科,其发展步伐在近50年来不断加快。文章回顾了近百年来大气科学在探测、数值天气预报和气候研究3方面所取得的主要成就,并对大气科学在21世纪的潜在发展作一展望。大气探测、计算能力和信息输送方面的技术进步无疑是近代和未来大气科学迅速发展的巨大动力。这些技术进步促使数值模式分辨率在不断提高,越来越多的实测和卫星等遥感资料在通过反演和同化进入模式初始条件和全球气象分析场,模式物理过程和参数化逐步趋向现实,从而使全球和区域数值预报水平持续提高。同时对大量观测资料的统计分析和许多气候子系统耦合模式的若干试验,大大提高了对造成气候变化和影响的物理、动力机制的认识;特别是对全球气温变暖,其中人类活动的影响,以及ENSO的发生、发展和消亡的机制和过程的认识。近期数值天气预报则趋向于模式发展的统一、预报时效的增加和对有足够成员且有代表性的集合预报的日益重视。气候研究将致力于减少各物理和化学过程参数化、分辨率等因素在模式中的不确定性,逐步达到跨月、季节直至年代际气候变化的合理预测。可以预言在不久的将来,地球-空间系统各变量的观测和预报将逐步数字化、自动化,人们可提前3~5 d得知灾害性天气发生时间和地点的概率,人工影响天气等学科在21世纪将会有突破。同时,可以看到世界各国共同协作建立地球-空间综合观测系统,发展能“包罗万象”的地球-空间-减灾的统一模式。然后综合利用大量观测和模式资料,及时掌握地球-空间系统中的各尺度变化规律,以确保人类社会的持续发展。 相似文献
13.
利用1961—1990年江淮流域逐日降水资料、NCEP/NCAR再分析资料和HadCM3 SRES A1B情景下模式预估资料,采用典型相关分析统计降尺度方法,评估降尺度模型对当前极端降水指数的模拟能力,并对21世纪中期和末期的极端降水变化进行预估。结果表明：通过降尺度能够有效改善HadCM3对区域气候特征的模拟能力,极端降水指数气候平均态相对误差降低了30%～100%,但降尺度结果仍然在冬季存在湿偏差、夏季存在干偏差;在SRES A1B排放情景下,该区域大部分站点的极端强降水事件将增多,强度增大,极端强降水指数的变化幅度高于平均降水指数,且夏季增幅高于冬季;冬季极端降水贡献率（R95t）在21世纪中期和末期的平均增幅分别为14%和25%,夏季则分别增加24%和32%。 相似文献
14.
Desert-fringe vegetation growing over bright, sandy soils reduces the surface albedo from above 0.4 to well be-low 0.3. Called desert-scrub, these shrubs form a predominantly vertical clumps protruding from the soil-level, thereby significantly increasing the coefficient of turbulent heat transfer from the surface. The impact on global and desert-belt climate of changes in these two surface characteristics was simulated by a multi-layer energy balance model. Evaluated only as a forcing to a further climatic change (that is, without accounting for any possible feedbacks) the results are: if vegetation (such as apparently existed under the warmer climate of 6,000 BP) grows over large areas in the arid, currently bare-soil regions, the annual Northern Hemisphere surface temperature increases by 0.7oC (by 0.6oC in July ), the surface temperature over land in the 20-30oN zone increases by 0.9oC in both the annual and the July means, and the land-ocean annual temperature contrast in this zone increases by 0.25oC (0.2oC in July). These results represent the combined influence of the reduction in the surface albedo and of the increase in the coefficient of turbulent heat transfer. In the desert-belt zones, the increase in the transfer coefficient sharply reduces the land temperature and the land-ocean temperature contrast from the values produced by the albedo change alone. This reduction must be attributed to the increased land-to-ocean circulation (which our model does not evaluate ex-plicitly). Considering that a stronger circulation (resulting from land-ocean temperature contrast) generally forces a higher rainfall, the vegetation which emerged in the arid regions during the post-glacial optimum should be consid-ered a. significant positive feedback towards a still warmer, and also a more pluvial, climate. Our study may have im-plications for the 21st century, if the global warming expected from the enhanced greenhouse effects is accompanied by increased precipitation over the continents. 相似文献
15.
利用国家气候中心完成的RegCM4区域气候模式在RCP4.5和RCP8.5两种排放路径下的气候变化动力降尺度试验结果,在检验模式对基准期(1986—2005年)气温和降水模拟能力基础上,进行华北区域21世纪气候变化预估分析。结果表明:RegCM4对华北区域基准期气温和降水的模拟能力较好。未来21世纪,两种情景下华北区域气温、降水、持续干期(consecutive dry days, CDD)和强降水量(R95p)变化逐渐增大,但变化幅度在高排放的RCP8.5情景下更为显著,其中近期(2021—2035年)、中期(2046—2065年)、远期(2080—2098年)RCP8.5情景下年平均气温分别升高1.77、3.44、5.82℃,年平均降水分别增加8.1%、14%、19.3%,CDD分别减少3、3、12 d, R95p分别增加30.8%、41.9%、69.8%。空间上,未来21世纪华北区域内年、冬季、夏季平均气温将一致升高,夏季升温幅度最大;年、冬季、夏季平均降水整体以增加为主,冬季降水增加幅度最大;CDD以减少为主,但近期和中期在山西和京津冀有所增加,而R95p以增加为主,表明21世纪华北区域干旱事件逐渐减少、极端降水事件不断增加。 相似文献
16.
Joshua W. Busby Kerry H. Cook Edward K. Vizy Todd G. Smith Mesfin Bekalo 《Climatic change》2014,124(4):717-731
Given its high dependence on rainfed agriculture and its comparatively low adaptive capacity, Africa is frequently invoked as especially vulnerable to climate change. Within Africa, there is likely to be considerable variation in vulnerability to climate change both between and within countries. This paper seeks to advance the agenda of identifying the hot spots of what we term “climate security” vulnerability, areas where the confluence of vulnerabilities could put large numbers of people at risk of death from climate-related hazards. This article blends the expertise of social scientists and climate scientists. It builds on a model of composite vulnerability that incorporates four “baskets” or processes that are thought to contribute to vulnerability including: (1) physical exposure, (2) population density, (3) household and community resilience, and (4) governance and political violence. Whereas previous iterations of the model relied on historical physical exposure data of natural hazards, this paper uses results from regional model simulations of African climate in the late 20th century and mid-21st century to develop measures of extreme weather events—dry days, heat wave events, and heavy rainfall days—coupled with an indicator of low-lying coastal elevation. For the late 20th century, this mapping process reveals the most vulnerable areas are concentrated in Chad, the Democratic Republic of the Congo, Niger, Somalia, Sudan, and South Sudan, with pockets in Burkina Faso, Ethiopia, Guinea, Mauritania, and Sierra Leone. The mid 21st century projection shows more extensive vulnerability throughout the Sahel, including Burkina Faso, Chad, Mali, northern Nigeria, Niger, and across Sudan. 相似文献
17.
Future Changes of Drought and Flood Events in China under a Global Warming Scenario 总被引：1，自引：0，他引：1 
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下载免费PDF全文 This study investigates the impact of global warming on drought/flood patterns in China at the end of the 21st century based on the simulations of 22 global climate models and a regional climate model(RegCM3) under the SRES(Special Report on Emissions Scenarios) A1B scenario.The standardized precipitation index(SPI),which has well performance in monitoring the drought/flood characteristics(in terms of their intensity,duration,and spatial extent) in China,is used in this study.The projected results of 22 coupled models and the RegCM3 simulation are consistent.These models project a decrease in the frequency of droughts in most parts of northern China and a slight increase in the frequency in some parts of southern China.Considering China as a whole,the spatial extents of droughts are projected to be significantly reduced.In contrast,future flood events over most parts of China are projected to occur more frequently with stronger intensity and longer duration than those prevalent currently.Additionally,the spatial extents of flood events are projected to significantly increase. 相似文献
18.
Climate Simulation and Future Projection of Precipitation and the Water Vapor Budget in the Haihe River Basin 下载免费PDF全文
下载免费PDF全文 The climatological characteristics of precipitation and the water vapor budget in the Haihe River basin (HRB) are analyzed using daily observations at 740 stations in China in 1951-2007 and the 4-time daily ERA40 reanalysis data in 1958-2001. The results show that precipitation and surface air temperature present significant interannual and interdecadal variability, with cold and wet conditions before the 1970s but warm and dry conditions after the 1980s. Precipitation has reduced substantially since the 1990s, with a continued increase of surface air temperature. The total column water vapor has also reduced remarkably since the late 1970s. The multi-model ensemble from the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) has capably simulated the 20th century climate features and successfully reproduced the spatial patterns of precipitation and temperature. Unfortunately, the models do not reproduce the interdecadal changes. Based on these results, future projections of the climate in the HRB are discussed under the IPCC Special Report on Emissions Scenarios (SRES) B1, A1B, and A2. The results show that precipitation is expected to increase in the 21st century, with substantial interannual fluctuations relative to the models’ baseline climatology. A weak increasing trend in precipitation is projected before the 2040s, followed by an abrupt increase after the 2040s, especially in winter. Precipitation is projected to increase by 10%-18% by the end of the 21st century. Due to the persistent warming of surface air temperature, water vapor content in the lower troposphere is projected to increase. Relative humidity will decrease in the mid-lower troposphere but increase in the upper troposphere. On the other hand, precipitation minus evaporation remains positive throughout the 21st century. Based on these projection results, the HRB region is expected to get wetter in the 21st century due to global warming. 相似文献
19.
An assessment of future change in synoptic conditions over the Arabian Peninsula throughout the twenty-first century was performed using 20 climate models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) database. We employed the mean sea level pressure (SLP) data from model output together with NCEP/NCAR reanalysis data and compared the relevant circulation types produced by the Lamb classification scheme for the base period 1975–2000. Overall, model results illustrated good agreement with the reanalysis, albeit with a tendency to underestimate cyclonic (C) and southeasterly (SE) patterns and to overestimate anticyclones and directional flows. We also investigated future projections for each circulation-type during the rainy season (December–May) using three Representative Concentration Pathways (RCPs), comprising RCP2.6, RCP4.5, and RCP8.5. Overall, two scenarios (RCP4.5 and RCP 8.5) revealed a statistically significant increase in weather types favoring above normal rainfall in the region (e.g., C and E-types). In contrast, weather types associated with lower amounts of rainfall (e.g., anticyclones) are projected to decrease in winter but increase in spring. For all scenarios, there was consistent agreement on the sign of change (i.e., positive/negative) for the most frequent patterns (e.g., C, SE, E and A-types), whereas the sign was uncertain for less recurrent types (e.g., N, NW, SE, and W). The projected changes in weather type frequencies in the region can be viewed not only as indicators of change in rainfall response but may also be used to inform impact studies pertinent to water resource planning and management, extreme weather analysis, and agricultural production. 相似文献
20.
Jean-François Exbrayat Wouter Buytaert Edison Timbe David Windhorst Lutz Breuer 《Climatic change》2014,125(2):221-235
Future climate projections from general circulation models (GCMs) predict an acceleration of the global hydrological cycle throughout the 21st century in response to human-induced rise in temperatures. However, projections of GCMs are too coarse in resolution to be used in local studies of climate change impacts. To cope with this problem, downscaling methods have been developed that transform climate projections into high resolution datasets to drive impact models such as rainfall-runoff models. Generally, the range of changes simulated by different GCMs is considered to be the major source of variability in the results of such studies. However, the cascade of uncertainty in runoff projections is further elongated by differences between impact models, especially where robust calibration is hampered by the scarcity of data. Here, we address the relative importance of these different sources of uncertainty in a poorly monitored headwater catchment of the Ecuadorian Andes. Therefore, we force 7 hydrological models with downscaled outputs of 8 GCMs driven by the A1B and A2 emission scenarios over the 21st century. Results indicate a likely increase in annual runoff by 2100 with a large variability between the different combinations of a climate model with a hydrological model. Differences between GCM projections introduce a gradually increasing relative uncertainty throughout the 21st century. Meanwhile, structural differences between applied hydrological models still contribute to a third of the total uncertainty in late 21st century runoff projections and differences between the two emission scenarios are marginal. 相似文献