中国地区极端降水事件的未来变化对人口的影响

Increasing impacts from extreme precipitation on population over China with global warming

在全球增温背景下,中国地区是全球气候变化的敏感区之一.预估并理解未来极端降水的变化及其影响对于减缓和适应策略的制定具有重要的指示意义.本文基于CMIP5多模式预估的极端降水,结合不同社会经济路径下的人口预估数据,分析了不同全球温升阈值下中国地区极端强降水和极端干期的变化及其对人口的影响.研究表明,中国地区极端强降水事件将随增温普遍增强(中国地区平均Rx5day将增强~6.5%/K),因此其对人口的影响随全球温升而持续增加.而极端干期则呈偶极子型变化,在中国南部延长、北部缩短.由于气候变化和人口分布的不均匀性,中国东南部是极端降水变化对人口影响的敏感地区.比较未来气候变化和人口分布变化的相对作用,极端降水本身的未来变化将主导其对人口的影响,而人口分布变化的影响相对较小.

Precipitation-related extremes are among the most impact-relevant consequences of a warmer climate,particularly for China,a region vulnerable to global warming and with a large population.Understanding the impacts and risks induced by future extreme precipitation changes is critical for mitigation and adaptation planning.Here,extreme precipitation changes under different levels of global warming and their associated impacts on populations in China are investigated using multimodel climate projections from the Coupled Model Intercomparison Project Phase 5 and population projections under Shared Socioeconomic Pathways.Heavy precipitation would intensify with warming across China at a rate of 6.52%(5.22%-8.57%)per degree of global warming.The longest dry spell length would increase(decrease)south(north)of-34°N.The low warming target of the Paris Agreement could substantially reduce the extreme precipitation related impacts compared to higher warming levels.For the area weighted average changes,the intensification in wet extremes could be reduced by 3.22%,9.42%and 16.70%over China,and the lengthening of dry spells could be reduced by 0.72%,4.75%and 5.31%in southeastern China,respectively,if global warming is limited to 1.5℃as compared to 2,3 and 4℃The Southeastern China is the hotspot of enhanced impacts due to the dense population.The impacts on populations induced by extreme precipitation changes are dominated by climate change,while future population redistribution plays a minor role.