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极端降水人口暴露度随全球变暖显著增加

Significant increase of the global population exposure to increased precipitation extremes in the future

[2021-09-26]


  【中文介绍】

   

       随着全球增暖,极端降水及其引发的灾害已造成了重大经济损失,严重影响局地生态环境和社会经济的可持续发展。如2021年中国河南7•20暴雨,造成302人死亡,50人失踪,直接经济损失超过1140亿元。因此,亟需预估和评估未来持续变暖背景下极端降水演变趋势及其人口暴露度的变化,为政府部门制定应对气候变化对策提供科学支撑。


       本研究主要基于最新CMIP6的历史模拟和未来四种不同排放情景(SSP1-2.6、SSP2-4.5、SSP3-7.0和SSP5-8.5)试验数据展开;极端降水日数定义为日降水量超过第99百分位阈值的降水事件。研究结果指出,在21世纪,全球陆地区域极端降水发生概率呈现明显增加趋势;尤其是在SSP5-8.5情景下,到了21世纪末,全球陆地区域平均极端降水发生概率相比当前气候增加了约1.8倍;即使在SSP1-2.6低排放情景下,极端降水也呈现明显增加趋势,但增加幅度相对较小。由此造成的极端降水人口暴露度也显著增加,在SSP5-8.5情景下,到了21世纪末至少增加了约50%,其中极端降水变化的贡献达到了约46%。但气候和人口变化的贡献也存在显著的区域差异,比如非洲大部地区,极端降水人口暴露度的增加主要是由于非洲人口的快速增长造成的,其贡献明显大于气候变化;非洲地区也成为了未来极端降水人口暴露度的高值区域之一。

 

  【英文介绍】

   

  Precipitation extremes and associated hazards often cause agricultural losses and infrastructure damage and even exert negative impacts on human health. It is thus crucial to assess future changes in precipitation extremes and exposure under future warming scenarios to improve the mitigation of climate change. On the basis of Coupled Model Intercomparison Project phase 6 simulations, we find that occurring probabilities of precipitation extremes that exceed the 99th percentile threshold are projected to increase over global lands in the coming century, especially under the no-mitigation scenario of SSP5-8.5. Under this scenario, by the end of this century, occurrences of aggregations of precipitation extremes over global lands are expected to increase by approximately 1.8 times. Increases are also expected even if early mitigation is conducted via SSP1-2.6. Accordingly, global aggregate exposure would increase by at least 50% in the future under SSP5-8.5. Changes in precipitation extremes will exert a substantial influence on population exposure, of which contribution will be up to 46% under SSP5-8.5 by the end of this century. The future maximum centers of exposure are concentrated over East Asia, South Asia, the Mediterranean basin, and eastern North America, as in the current state. However, the rapid increase in population over some parts of Africa plays a larger role than climate change and significantly increases the exposure in these regions. As a result, regions of Africa will become other high-exposure global centers in the future. Climate change mitigation should be thus the key policy response to reduce population exposure in the future over most global regions.


  【关键图表




图1. 在SSP5-8.5情景下,预估的21世纪早期、中期和末期全球陆地区域极端降水人口暴露度分布(左)与相对当前气候的变化(右)

Figure 1. Figure 6. Projected changes in population exposure to precipitation extremes in the future under the SSP5-8.5 scenario. The left column shows the population exposure in the future, and the right column shows the associated relative changes with respect to the current state.


                                

  引用格式       

              

  Chen, H. P.*, and J. Q. Sun, 2021: Significant increase of the global population exposure to increased precipitation extremes in the future. Earth's Future, 9, e2020EF001941. https://doi.org/10.1029/2020EF001941















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