自然气候变异与人为气候变化对径流影响研究进展

在回顾IPCC于1990-2007年4次关于气候变化对径流影响的评估报告进展的基础上，将第一次与第二次评估报告归纳为第一代--以气候均值变化对径流影响及其适应为主要特征；第三次与第四次评估报告为第二代--突出人为气候变化与自然气候变异对径流影响及其适应问题，分析了常规的气候变化对水文水资源影响评估方法的发展过程及存在的问题。研究结果反映了年代际时间尺度的自然气候变异的影响，而未能考虑与极端事件发生频次和强度变化密切相联的日、季和年际尺度的气候变异的影响，从而低估了气候变暖对洪水、干旱以及农业灌溉需水的负面作用。在介绍国内外研究的基础上，为第五次IPCC评估报告提出了加强交叉学科综合研究的建议。

Advances in Studying Impacts of Natural Climate Variability and Anthropogenic Climate Change on Streamflow

Based on the review of the successive four assessment reports of the IPCC WGII on climate change impacts on streamflow from 1990 to 2007, it is summarized that the First (FAR) and Second (SAR) Assessment Reports were regarded as the first generation studies, featuring the impacts of mean climate change on streamflow and the adaptation to it, while the Third (TAR) and Forth (AR4) Assessment Reports as second generation studies, emphasizing the impacts of anthropogenically forced and natural climate changes on streamflow and the adaptation to them. The progresses and issues in the research methodologies of the impacts of climate change on hydrology and water resources are analyzed. It is pointed out that the impacts of decadal and multi-decadal variability of climatic variables on streamflow can be identified, but changes in interannual and daily variabilities are not taken into account in the conventional methodology of hydrological impact studies. As the results, the impacts of climate change on extreme events, such as droughts, floods and irrigation water demands are underestimated. As for further studies, the paper comes to conclusion suggesting to emphasize the interdisciplinary science study of hydrology and climatology in the next IPCC Assessment Report.