《Global environmental change》上刊登的“气候变化和全球水资源”

作者：Arnell N W.

刊物：《Global environmental change》,1999年, 第9卷, S31-S49页

关键词：气候变化;全球水资源;全球径流;气候变化造成的水文影响

摘要：到2025年，据估计全球人口将会达到80亿人，而这其中将有50亿人生活在水资源短缺的国家当中（水资源消耗量占到了国内可用水资源量的20%以上）。而气候变化将有可能在此基础上给某些地区施加更大的压力。本文将气候变化对全球水文模式和水资源所造成的影响进行了评估。本研究使用的气候变化情景是由哈德莱中心的气候模拟模型(HadCM2 and HadCM3)得到的，而在模拟全球河川径流时，则是使用一种宏观尺度的水文模型，其空间分辨率为0.5×0.5°。本研究中计算了各国水资源变化情况，其中包括本地地表产流以及从上游入境水量，并与为联合国世界淡水资源全面评估而进行的国家用水评估得到的结果做了比较。尽管不同的情景之间存在误差，但总体结果表明在高纬度地区平均年径流量都有所增加，在赤道附近的亚洲和非洲地区以及东南亚等中纬度和绝大多数亚热带地区，将会有所减少。由HadCM3情景所造成的径流变化通常与HadCM2情景所造成的结果类似，但这其中也存在着区域性差异。气候变化所导致的气温上升使得降雪等降水过程普遍减少，从而导致许多地区的积雪覆盖时间有所减少。这将会对这些区域产生径流的时间造成一定的影响，使得原本春季才会融化的冰雪在冬季就会产生径流。在HadCM2情景的平均情况下，到2025年，生活在那些面临用水压力的国家里的人口总数将会增加5300万人（其中包括那些没有受到气候变化影响的人）。而在HadCM3情景中，生活在水危机国家里的人口总数将会增加11300万人。然而，到2050年，在HadCM2情景中，生活在水危机国家的人口将会出现净减少（大约6900万人），而在HadCM3情景中，却会增加5600万人。本研究还表明，对未来用水情况的不同预测将会得到对于气候变化对用水压力造成的影响的不同预测结果。本文强调了对于影响进行评估时的大范围，同时也讨论了分析尺度和水资源影响指数定义等相关问题。

Climate change and global water resources

Authors：Arnell N W.

Journal：Global environmental change, 1999, 9: S31-S49.

Key Words：Climate change; Global water resources; Global runoff; Hydrological impacts of climate change

Abstract：By 2025, it is estimated that around 5 billion people, out of a total population of around 8 billion, will be living in countries experiencing water stress (using more than 20% of their available resources). Climate change has the potential to impose additional pressures in some regions. This paper describes an assessment of the implications of climate change for global hydrological regimes and water resources. It uses climate change scenarios developed from Hadley Centre climate simulations (HadCM2 and HadCM3), and simulates global river flows at a spatial resolution of 0.5×0.5° using a macro-scale hydrological model. Changes in national water resources are calculated, including both internally generated runoff and upstream imports, and compared with national water use estimates developed for the United Nations Comprehensive Assessment of the Freshwater Resources of the World. Although there is variation between scenarios, the results suggest that average annual runoff will increase in high latitudes, in equatorial Africa and Asia, and southeast Asia, and will decrease in mid-latitudes and most subtropical regions. The HadCM3 scenario produces changes in runoff which are often similar to those from the HadCM2 scenarios — but there are important regional differences. The rise in temperature associated with climate change leads to a general reduction in the proportion of precipitation falling as snow, and a consequent reduction in many areas in the duration of snow cover. This has implications for the timing of streamflow in such regions, with a shift from spring snow melt to winter runoff. Under the HadCM2 ensemble mean scenario, the number of people living in countries with water stress would increase by 53 million by 2025 (relative to those who would be affected in the absence of climate change). Under the HadCM3 scenario, the number of people living in countries with water stress would rise by 113 million. However, by 2050 there would be a net reduction in populations in stressed countries under HadCM2 (of around 69 million), but an increase of 56 million under HadCM3. The study also showed that different indications of the impact of climate change on water resource stresses could be obtained using different projections of future water use. The paper emphasises the large range between estimates of “impact”, and also discusses the problems associated with the scale of analysis and the definition of indices of water resource impact.

原文链接：

http://www.sciencedirect.com/science/article/pii/S0959378099000175

翻译：陈翔；审阅：高学睿