西南地区未来极端降水增加将导致其人口暴露风险加剧

Significant increase of precipitation extremes will enlarge its population exposure over Southwest China in the future

基于CN05.1观测数据和一套经过降尺度偏差校正处理的模式(NEX-GDDP-CMIP6)数据,结合泰勒图、GEV极值拟合等方法,综合评估了模式对西南地区极端降水变化的模拟性能,并系统分析了未来西南地区不同重现期的极端降水演变趋势及其人口暴露度变化。结果表明,NEX-GDDP-CMIP6模式及其集合(N-CMIP6-MME)能够较好地再现观测极端降水的时空变化特征,且多模式集合结果优于大多数单个模式。未来西南地区绝大多数区域的降水和极端降水将持续增加,十年一遇、二十年一遇极端降水事件也呈增加趋势,使得未来西南地区人口暴露于不同重现期极端降水的风险进一步增加。相比十年一遇,重现期为20 a的极端降水事件增加速度更快,增加范围更广,模式一致性也更高,对应的人口暴露度增加幅度更大。到2050年左右,在SSP1-2.6、SSP2-4.5、SSP3-7.0和SSP5-8.5情景下二十年一遇的RX1day(RX5day)分别增加了175.2%(148.9%)、216.0%(162.4%)、210.9%(156.8%)和274.3%(207.1%),对应人口暴露度分别增加了129.1%(118.8%)、177.7%(135.1%)、182.4%(143.2%)和237.5%(161.5%)。进一步分析指出,在未来极端降水人口暴露度的变化中,气候变化占主导作用,其次是人口变化和人口-气候协同作用的影响。

Based on the observation and a set of downscaling bias corrected model(NEX-GDDP-CMIP6)data,this study has investigated the model performance in simulating precipitation extremes over Southwest China using Taylor diagram and GEV fitting methods.Furthermore,the future changes of precipitation extremes that with different return intervals and their associated population exposure are also explored.Results show that NEX-GDDP-CMIP6 models and the multi-model ensemble(N-CMIP6-MME)can reasonably capture the spatial-temporal characteristics of changes in precipitation extremes over Southwest China,and N-CMIP6-MME out performs most of individual models.In the future,the precipitation extremes are expected to significant increases over most regions of Southwest China,including the extreme events that occurring once in 10 or 20 years,which will further increase the risk of population exposure to these extremes.Additionally,for the more extreme events(once in 20-year),the increasing magnitude of its occurring probability would be much greater and it would also exert a larger increase of its associated population exposure,when compared to the events of once in 10-year.Around the year of 2050,the occurring probabilities of the RX1day(RX5day)extremes that occurring once in 20-year are expected to increase by 175.2%(148.9%),216.0%(162.4%),210.9%(156.8%),and 274.3%(207.1%)under SSP1-2.6,SSP2-4.5,SSP3-7.0and SSP5-8.5 scenario,respectively.Correspondingly,thepopulation exposuresare projected to respective increase by 129.1%(118.8%),177.7%(135.1%),182.4%(143.2%),and 237.5%(161.5%).Further analyses indicate that the increase of population exposure to the precipitation extreme over Southwest China is mainly due to the significant increase of precipitation extremes,and the changes in populations and their interaction generally present a negative contribution.