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1.
量化人类活动在气候变化中的定量贡献是气候变化检测归因研究的核心科学问题,也是提高气候变化预测和预估水平的重要科学基础.本文基于最新的第6次国际耦合模式比较计划(CMIP6)多模式历史归因模拟试验(DAMIP),检测了人为因素(ANT)和自然因素(NAT)对近百年(1915—2014年)全球地表气温多尺度变化的影响,归因了温室气体(GHG)、气溶胶(AA)、土地利用(LU)等不同人为因素对全球地表气温长期变化的相对贡献及南北半球差异.结果显示,近百年来人为因素引起的全球陆地实际增温约为1.1℃(0.8℃～1.3℃),对南北半球的贡献则分别约为0.7℃和1.2℃;全球大多数区域人为排放GHG和AA的显著作用在1960—1980年期间就能够被检测到,其中北半球AA的冷却作用要超前于GHG的增温效应;气候系统内部自然变率是调制大多数区域气温年代际(10～30年)及多年代际变率(30～60年)的主导因子,而人为和自然外强迫在全球地表气温年代际变率中的方差贡献约为5%～20%,但二者在北半球尤其在东亚和欧洲中高纬度地区地表气温多年代际变率中的方差贡献可达50%.人为因素强迫可使近50年(1965—... 相似文献
2.
基于CMIP5多模式评估人为和自然因素外强迫在中国区域气候变化中的相对贡献 总被引：1，自引：0，他引：1
《中国科学:地球科学》2016,(2)
基于观测资料和CMIP5多模式的历史试验(考虑所有驱动因子)以及单因子强迫气候归因试验结果,估算了温室气体、气溶胶、土地利用及自然因素等外强迫在中国区域气候变化中的相对贡献.结果表明,人为和自然外强迫的共同作用可解释近30年观测气温变化的95%~99%,其中温室气体引起的温度变化是观测增温的2~3倍,而气溶胶起到了显著的冷却降温作用;人为和自然因素外强迫对近几十年观测降水的变化的可能贡献约为65%~78%,其中,气溶胶和温室气体是中国区域降水的主要外强迫因子,尤其气溶胶主导着中国东部降水变化的分布型,而自然因素外强迫的贡献主要体现在干旱半干旱区.人类活动主导了近60年来中国区域气温的长期非线性趋势,特别是从20世纪60年代开始温室气体的影响强度逐渐增大,是中国区域气候变暖最主要的贡献者;不同外强迫因子对中国区域降水长期非线性趋势的影响具有明显的区域差异,温室气体是20世纪70年代以后干旱半干旱区降水逐渐增加的主要贡献者,而气溶胶的主要影响使湿润半湿润区降水有较为明显下降趋势,土地利用和自然因素外强迫也会造成降水呈减少的趋势.通过最优指纹法(Optimal Fingerprinting)的检测可知,人类活动能够很好地解释近60年来中国区域特别是湿润半湿润区观测气温的变化,其中温室气体的单独作用能够清晰地从观测结果中检测出来;由于多模式结果的不确定性,观测降水变化的归因目前还无法通过残余一致性检测.需要指出的是,尽管本文的研究结果还存在着一定的不确定性,但仍可为中国区域气候变化成因研究及其预测提供科学依据. 相似文献
3.
《中国科学:地球科学》2021,(6)
自工业革命以来,大气中温室气体浓度持续升高,但1998～2013年期间却出现了全球增暖减缓现象,挑战了现有的对全球温度变化机理的认识.第五次国际耦合模式比较计划(Coupled Model Inter-comparison Project Phase5, CMIP5)中众多当时最先进的气候模式都没能合理地模拟出该现象,引发了公众对气候模拟和预测的质疑.文章基于六种常用的全球表面温度观测资料集,评估了最近发布的28个CMIP6气候模式对21世纪初全球增暖减缓现象的模拟能力.结果显示,相对前一代的CMIP5模式,新一代的CMIP6模式尽管在年代尺度增暖速率模拟能力上有所提高,但大多数CMIP6模式依然未能重现出全球增暖减缓现象.在28个CMIP6模式中,只有4个成功模拟出了增暖减缓,其他模式普遍高估了1998～2013年期间的增暖速率,呈现出明显的增暖加速,而不是观测到的增暖减缓.进一步分析表明,气候模式能否成功模拟出增暖减缓现象的关键在于其能否准确区分并模拟出两种不同来源的温度变化信号,即人类排放温室气体导致的长期增暖信号和气候系统内部短期的自然变率信号,特别是年际、年代际和多年代际这三种尺度的自然变率. 4个复现出增暖减缓现象的模式都较为合理地模拟出了长期增暖趋势和三种关键尺度自然变率.上述评估结果为改进气候模式对短期气候变化的模拟和预测能力提供了一个新的视角. 相似文献
4.
《中国科学:地球科学》2021,(6)
关于全球变暖及其对气候和环境影响的研究,目前主要是从绝对升温速率的角度进行分析,很少关注绝对增温率与多时间尺度变率对地表气温变化总方差的相对贡献,而这可能是一个衡量变暖趋势的生态气候效应更直接的指标.本研究分析了变暖趋势在1901～2016年全球陆表气温变化中的作用.在全球大部分地区,年平均的变暖趋势对于陆表气温变化总方差的贡献不到三分之一.而在南美洲东部、地中海和巽他群岛等区域,虽然绝对增温速率相对较小,但变暖趋势对当地陆表气温变化总方差的贡献超过了三分之二,且这些区域变暖趋势的季节差异也最小,与当地特有物种正在经历栖息地的异常消失相对应.这说明变暖趋势在地表气温变化中的贡献率,比绝对增温速率能更好地度量增暖趋势对局地生态系统的影响.因此,我们不仅要关注绝对增温率高的地区,更要关注增温率在局地地表气温变化中起主导作用的地区. 相似文献
5.
大气和地表之间热辐射交换引起的地气温度耦合(即大气温度反馈)是影响地表能量收支平衡的重要因子.文章旨在阐述大气温度反馈机理,讨论影响其强度和空间分布的主要因子;并以全球变暖为例,论述大气温度反馈如何与外强迫和气候反馈过程耦合最终对全球增暖产生贡献.基于ERA-Interim再分析资料,利用地表反馈响应分析方法,计算大气温度反馈核,以此来阐述大气温度反馈的物理机制及其强度的空间分布与气候态温度、水汽和云水含量空间分布的关系,以及全球增暖加速期间大气温度反馈对全球平均表面温度增加的贡献.分析表明大气温度反馈过程主要通过与气候系统外强迫和内部过程的耦合作用,将各独立过程引起的地表能量收支异常信号放大.研究结果表明大气温度反馈显著放大了CO_2浓度升高、冰雪融化、水汽含量增加和海洋热量吸收减缓引起的地表增暖,削弱了云量增加引起的地表降温效应.同时,也放大了地表潜热通量增加造成的地表冷却效应.从全球平均结果来看,全球快速变暖前后,尽管外强迫和气候系统内部过程引起的全球平均总地面直接能量通量扰动为负,但大气温度反馈造成的全球平均总地面能量通量扰动却为正,且后者幅度远大于前者,这导致全球平均总地面净能量通量扰动正异常.由此可见,大气温度反馈对全球变暖起到了至关重要的作用. 相似文献
6.
《地球物理学进展》2016,(6)
利用NACR CCSM3.0气候系统模式的20世纪气候模拟试验(20C3M)结果,在检验模式对全球季风区、季风降水模态以及1979-1999年全球季风降水趋势的模拟性能基础上,研究了全强迫、自然强迫以及人类活动强迫等因子对20世纪全球季风降水变化趋势的可能影响。结果表明:全球季风降水在全强迫的作用下在20世纪呈线性增长趋势,且这个增长趋势主要是由于人类活动强迫影响造成的,进一步分析得到主要是由于人类活动强迫中的温室气体因子影响所导致的.在温室气体强迫作用下会产生"东太平洋冷—西太平洋暖"这一形势,有利于水汽传输合并进入东半球季风区,加上其引起的全球海陆热力差和半球热力差的增大会加大季风低压,使得相应的水汽辐合和越赤道气流的增大从而引起全球季风降水的增长.自然强迫作用下也会引起20世纪全球季风降水的增加,但增长趋势并不明显.而硫酸盐和黑碳气溶胶会减弱全球季风降水在20世纪的增长趋势,硫酸盐气溶胶主要引起北半球季风降水的减少,而黑碳气溶胶主要引起南半球季风降水的减少. 相似文献
7.
《中国科学:地球科学》2015,(4)
基于实际气候主要由气候系统自然变率和外强迫影响二者叠加而形成的认识,利用统计和动力相结合的方法对东亚表面气温(EATs)未来30年的演变进行了预测.关于自然变率部分,利用1901~1999年的观测资料,通过计算海温模态与EATs内部变率(EATs_int)的超前-滞后相关,选取几个主要海温模态作为预测因子,建立了EATs_int年代际内部变率的多元线性回归模型.首先对2000~2005年进行了后报检验,发现该模型有较好的预测能力.于是,根据海温模态的准周期性,利用该模型对未来30年进行了预测试验,得到了内部变率的预测结果.关于外强迫影响部分,利用参与政府间气候变化专门委员会第5次评估报告的19个耦合模式的历史试验和21世纪RCP4.5情景的预估结果,通过二阶拟合,得到EATs相对于1970~1999年的趋势变化(即外强迫的影响信号).将得到的内部变率和趋势进行叠加,形成最后的预测结果(Re_EATs).该结果显示:在2010~2040年,温度将呈波动性变化,其中在2015~2030年缓慢降温,之后开始上升.将这一结果与第五期耦合模式相互比较计划(CMIP5)的年代际预测进行对比,发现它与多数单个模式得到的预测结果及多模式预测集合平均的结果定性一致,表明利用统计和动力相结合的方法来预测东亚气温具有一定的合理性. 相似文献
8.
综合现代观测、历史代用资料和气候模式模拟,本文综述了大西洋经向翻转环流(AMOC)的过去、现在和未来的演变特征,以及AMOC对区域和半球尺度地表气温(SAT)的影响.代用资料重建结果表明, AMOC从19世纪末开始减弱, 20世纪整体减弱,但信度较低.直接观测结果显示, 2004～2016年间AMOC减弱,但无法区分出其年代际变化和长期趋势.气候模式预测可知,若温室气体排放持续增加, AMOC未来将会减弱,但在2100年前不会出现突然的崩溃. AMOC的热力作用表现为,强AMOC导致北大西洋海表面热通量释放和经向热输送增强,造成半球尺度SAT增加,千年尺度的气候冷(暖)期对应AMOC减弱(增强).强AMOC的经向热输送能够影响北极增暖,并通过北极海冰和AMOC之间的互反馈作用影响区域SAT异常和极端温度.在动力方面,强AMOC调制源自北大西洋沿北半球中高纬度地区传播的罗斯贝波活动,引起乌拉尔和西伯利亚地区的环流异常变率增加,对欧亚大陆中高纬地区极端冷、暖事件发生频率均有显著影响.此外, AMOC也可以通过对行星尺度环流的动力调整影响区域和全球地表气温异常.多年代际AMOC变率与大西洋多... 相似文献
9.
为了研究2 0世纪中国地区主磁场变化, 首先使用最新的全球模型IGRF11, CALS3K. 4 (3K. 4) 和GUFM1进行计算, 并分析了1900—1990年的主磁场年变率均值的变化; 然后基于1960—2000年以10年为间隔的实测数据, 结合全球模型CM4与区域模型泰勒(Taylor)多项式(TY)模型分析了中国地区主磁场的年变率分布及年变率均值, 并与上述几种全球模型进行了比较． 结果显示: 20世纪利用IGRF11, GALS3K.4和GUFM1模型得到的主磁场的年变率均值均很接近. 它们所绘制的1960—2000年中国地区的主磁场年变率分布类似． 其原因主要是由于它们的建模原理相同且截断阶数接近所致． 基于实测点绘制的年变率分布与全球模型基本一致, X分量的年变率逐年减少, Y、 Z、 F分量的年变率均呈现先减小后增大的趋势．但两者也存在一定差异, 主要原因是由于更高密度的实测点及使用区域模型所致． 结果还显示了基于实测值绘制的年变率均值变化与CM4较为接近. 作者认为 CM4模型可以较好地反映中国地区主磁场的变化． 相似文献
10.
季节性温差(夏温与冬温之差)变化是地球气候系统的重要组成部分.遗憾的是,在东亚地区较短的气象观测记录限制了对季节性温差变化的认识.本研究诊断了东亚地区树轮气候信号,严格筛选了10条对冬季(上年12月至当年2月)和12条对夏季(当年6～8月)温度变化响应敏感的年表.基于筛选的树轮资料,重建了公元1376～1995年东亚地区冬季和夏季温度变化序列,并与气候模拟结果进行了对比分析.结果显示:过去600年,与冬季相比,夏季温度对赤道火山喷发造成的降温效应以及对工业革命以来温室气体强迫引起的增温效应响应更为显著;温室气体强迫使得东亚季节性温差自19世纪70年代起持续减弱,且20世纪90年代以来,季节性温差减弱趋势已超出过去600年的自然变率范围;气候模式可以基本模拟出重建所揭示的冬季和夏季的温度年代际变率及趋势,但很大程度上低估了季节性温差变化幅度,这主要是由于现有的气候模式低估了区域尺度温度变化对外强迫和气候系统内部变率模态响应的季节差异.本研究强调了利用气候重建资料对气候模式模拟季节性温度变化性能验证的重要性,明晰了如果未来温室气体强迫持续增强,东亚地区季节性温差将进一步减弱的认识. 相似文献
11.
XIAO Dong ZHOU XiuJi & ZHAO Ping Chinese Academy of Meteorological Sciences Beijing China; State 《中国科学:地球科学(英文版)》2012,(9):1504-1517
Despite many studies on reconstructing the climate changes over the last millennium in China,the cause of the China’s climate change remains unclear.We used the UVic Earth System Climate Model(UVic Model),an Earth system model of intermediate complexity,to investigate the contributions of climate forcings(e.g.solar insolation variability,anomalous volcanic aerosols,greenhouse gas,solar orbital change,land cover changes,and anthropogenic sulfate aerosols) to surface air temperature over East China in the past millennium.The simulation of the UVic Model could reproduce the three main characteristic periods(e.g.the Medieval Warm Period(MWP),the Little Ice Age(LIA),and the 20th Century Warming Period(20CWP)) of the northern hemisphere and East China,which were consistent with the corresponding reconstructed air temperatures at century scales.The simulation result reflected that the air temperature anomalies of East China were larger than those of the global air temperature during the MWP and the first half of 20CWP and were lower than those during the LIA.The surface air temperature of East China over the past millennium has been divided into three periods in the MWP,four in the LIA,and one in the 20CWP.The MWP of East China was caused primarily by solar insolation and secondarily by volcanic aerosols.The variation of the LIA was dominated by the individual sizes of the contribution of solar insolation variability,greenhouse gas,and volcano aerosols.Greenhouse gas and volcano aerosols were the main forcings of the third and fourth periods of the LIA,respectively.We examined the nonlinear responses among the natural and anthropogenic forcings in terms of surface air temperature over East China.The nonlinear responses between the solar orbit change and anomalous volcano aerosols and those between the greenhouse gases and land cover change(or anthropogenic sulfate aerosols) all contributed approximately 0.2℃ by the end of 20th century.However,the output of the energy-moisture balance atmospheric model from UVic showed no obvious nonlinear responses between anthropogenic and natural forcings.The nonlinear responses among all the climate forcings(both anthropogenic and natural forcings) contributed to a temperature increase of approximately 0.27℃ at the end of the 20th century,accounting for approximately half of the warming during this period;the remainder was due to the climate forcings themselves. 相似文献
12.
Air temperature feedback results from the thermal-radiative coupling between the atmosphere and the surface and plays an important role in surface energy balance. This paper reveals the contribution of air temperature feedback to the global warming from 1980 to 2000. The air temperature feedback kernel, evaluated using the ERA-Interim reanalysis data, is used to discuss the physical mechanism for air temperature feedback, the dependency of the strength of air temperature feedback on the climatological spatial distributions of air temperature, water vapor and cloud content, and the contributions of air temperature feedback to rapid global warming. The coupling between temperature feedback and each of the external forcings and individual feedback processes will amplify the anomaly of direct energy flux convergence at the surface induced by the external forcings and individual processes. The air temperature feedback amplifies the initial surface warming due to the increase in CO2 concentration, ice and snow melting, increase in water vapor, and change in ocean heat storage. It also amplifies the surface warming due to the longwave radiaitve forcing associated with the increase in cloud cover, which acts to suppress the cooling of the shortwave effect of cloud forcing. Overall, temperature feedback plays an important role in the global warming from 1980 to 2000, as the net positive contribution to the perturbation of global mean energy flux at the surface from the air temperature feedback is larger than the net negative contribution from external forcing and all non-temperature feedbacks. 相似文献
13.
M. R. Allen N. P. Gillett J. A. Kettleborough G. Hegerl R. Schnur P. A. Stott G. Boer C. Covey T. L. Delworth G. S. Jones J. F. B. Mitchell T. P. Barnett 《Surveys in Geophysics》2006,27(5):491-544
We assess the extent to which observed large-scale changes in near-surface temperatures over the latter half of the twentieth century can be attributed to anthropogenic climate change as simulated by a range of climate models. The hypothesis that observed changes are entirely due to internal climate variability is rejected at a high confidence level independent of the climate model used to simulate either the anthropogenic signal or the internal variability. Where the relevant simulations are available, we also consider the alternative hypothesis that observed changes are due entirely to natural external influences, including solar variability and explosive volcanic activity. We allow for the possibility that feedback processes, other than those simulated by the models considered, may be amplifying the observed response to these natural influences by an unknown amount. Even allowing for this possibility, the hypothesis of no anthropogenic influence can be rejected at the 5% level in almost all cases. The influence of anthropogenic greenhouse gases emerges as a substantial contributor to recent observed climate change, with the estimated trend attributable to greenhouse forcing similar in magnitude to the total observed warming over the 20th century. Much greater uncertainty remains in the response to other external influences on climate, particularly the response to anthropogenic sulphate aerosols and to solar and volcanic forcing. Our results remain dependent on model-simulated signal patterns and internal variability, and would benefit considerably from a wider range of simulations, particularly of the responses to natural external forcing. 相似文献
14.
Based on observations and historical simulations from the fifth phase of the Coupled Model Intercomparison Project(CMIP5) archive, the contributions of human activities(including greenhouse gases(GHGs), anthropogenic aerosols(AAs), and land use(LU)) and external natural forcings(Nat) to climate changes in China over the past 50 years were quantified. Both anthropogenic and external natural forcings account for 95%–99% of the observed temperature change from 1951–1975 to 1981–2005. In particular, the temperature changes induced by GHGs are approximately 2–3 times stronger than the observed changes, and AAs impose a significant cooling effect. The total external forcings can explain 65%–78% of the observed precipitation changes over the past 50 years, in which AAs and GHGs are the primary external forcings leading to the precipitation changes; in particular, AAs dominate the main spatial features of precipitation changes in eastern China. Human activities also dominate the long-term non-linear trends in observed temperature during the past several decades, and, in particular, GHGs, the primary warming contributor, have produced significant warming since the 1960 s. Compared to the long-term non-linear trends in observed precipitation, GHGs have largely caused the wetting changes in the arid-semiarid region since the 1970 s, whereas AAs have led to the drying changes in the humid-semihumid region; both LU and Nat can impose certain impacts on the long-term non-linear trends in precipitation. Using the optimal fingerprinting detection approach, the effects of human activities on the temperature changes can be detected and attributed in China, and the effect of GHGs can be clearly detected from the observations in humid-semihumid areas. However, the anthropogenic effects cannot be detected in the observed precipitation changes, which may be due to the uncertainties in the model simulations and to other issues. Although some results in this paper still need improvement due to uncertainties in the coupled models, this study is expected to provide the background and scientific basis for climate changes to conduct vulnerability and risk assessments of the ecological systems and water resources in the arid-semiarid region of China. 相似文献
15.
Marta Marcos Ben Marzeion Sönke Dangendorf Aimée B. A. Slangen Hindumathi Palanisamy Luciana Fenoglio-Marc 《Surveys in Geophysics》2017,38(1):329-348
In this paper we review and update detection and attribution studies in sea level and its major contributors during the past decades. Tide gauge records reveal that the observed twentieth-century global and regional sea level rise is out of the bounds of its natural variability, evidencing thus a human fingerprint in the reported trends. The signal varies regionally, and it partly depends on the magnitude of the background variability. The human fingerprint is also manifested in the contributors of sea level for which observations are available, namely ocean thermal expansion and glaciers’ mass loss, which dominated the global sea level rise over the twentieth century. Attribution studies provide evidence that the trends in both components are clearly dominated by anthropogenic forcing over the second half of the twentieth century. In the earlier decades, there is a lack of observations hampering an improved attribution of causes to the observed sea level rise. At certain locations along the coast, the human influence is exacerbated by local coastal activities that induce land subsidence and increase the risk of sea level-related hazards. 相似文献
16.
The field area of the Earth’s lower (<3.2 km) clouds is shown to correlate significantly with the intensity of galactic cosmic rays in 1983–2010, with the sign of correlation reversing in 2003. The same effect is discovered in the correlation between air temperatures in various regions of the Earth and the relativistic electron fluxes with energies of 30–300 KeV that precipitate in winter (December–February). An energy-balance climate model is used to estimate the possible contribution of lower clouds to the globally averaged temperature in the indicated period. It is shown that the consideration of lower clouds as a radiative forcing allows one to explain the global warming of the last 30 years without employing the hypothesis of anthropogenic greenhouse heating.
相似文献17.
This study reports results from an analysis of the relationship between atmospheric forcing and model‐simulated water and energy fluxes for the North American Land Data Assimilation System Project Phase 2 (NLDAS‐2). The relationships between mean monthly precipitation and total runoff are stronger in the Sacramento (SAC) and variable infiltration capacity (VIC) models, which grew out of the hydrological community, than in the Noah and Mosaic models, which grew out of the soil‐vegetation‐atmosphere transfer (SVAT) community. The reverse is true for the relationship between mean monthly precipitation and evapotranspiration. In addition, surface energy fluxes in VIC are less sensitive to model forcing (except for air temperature) than those in the Noah and Mosaic model. Notwithstanding these general conclusions, the relationships between forcings and model‐simulated water and energy fluxes for all models vary for different seasons, variables, and regions. These findings will ultimately inspire a combination of SVAT‐type model energy components with hydrological model water components to develop a SVAT‐hydrology model to improve both evapotranspiration and total runoff simulations. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
18.
在最新的SRES A2和B2温室气体排放情景下,利用国际上7个气候模式针对未来全球变暖的数值模拟结果,本文着重分析了东亚区域气候21世纪的变化趋势. 研究揭示：中国大陆年均表面气温升高过程与全球同步,但增幅在东北、西部和华中地区较大,且表现出明显的年际变化;全球年均表面气温增幅纬向上大体呈带状分布,两极地区最为明显,并在北极地区达到最大;此外,21世纪后半段北半球高纬度地区的年平均强升温幅度主要来自于冬季增温. 在21世纪前50年,温室气体含量的增加除在一定程度上会增加青藏高原大部分夏季降水量外,不会对中国大陆其余地区的年、季节平均降水量产生较大影响;但持续的温室气体含量增加将最终导致大陆降水量几乎是全域性的增加. 相似文献
19.
利用NOAA/AVHRR归一化植被指数（NDVI）及观测气温与再分析地表气温的差值（Observation Minus Reanalysis, OMR）分析了植被覆盖状况对中国地表气温变化的影响.结果表明,地表气温OMR趋势值与NDVI在空间上呈现出显著的负相关关系,植被覆盖状况差（NDVI小于0.1）的区域地表升温较为显著,气温OMR趋势值超过0.2℃/10a,而植被覆盖度高（NDVI大于0.5）的区域气温OMR趋势值则变化不大,甚至出现降温.气温OMR趋势值对植被的季节变化还有着敏感的响应.不同区域植被覆盖状况的差异可能导致中国地表气温变化对全球变暖的响应不同,预测中国未来气候变化需要考虑植被覆盖状况及其动态变化的影响. 相似文献
20.
Modelling and analysis of the impact of irrigation on local arid climate over northwest China 总被引：1，自引：0，他引：1
This study focuses on how irrigation processes affect local climate over arid areas. The chosen study area is northwest China, a typical arid region where three dominant land‐use types are irrigated cropland, grassland, and desert. Observational analysis indicates that the highest precipitation, the coolest surface temperatures, and the slowest warming trend are seen over irrigated cropland from 1979 to 2005. The single column atmospheric model (SCAM), developed by the National Center for Atmospheric Research (NCAR), was used to investigate and better understand the differences in long‐term climate conditions and change over the above three land‐use types. The results indicate that local climate conditions are predominantly controlled by large‐scale forcing in this arid region and that local land surface forcing related to vegetation cover change and irrigation processes also has a significant impact. This study strongly suggests that a realistic climate forecast for this region can be achieved only with both accurate large‐scale and local climate forcing. The irrigated cropland of the region generates stronger evaporation that cools the surface and slows the warming trend more than does the evaporation from the natural grassland and desert. Stronger evaporation also significantly increases precipitation, potentially alleviating the stress of irrigation demands in arid regions. A series of sensitivity SCAM simulations indicate that a drier and warmer climate occurs with decreasing vegetation cover in the irrigated cropland region. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献