全球变暖与城市效应共同作用下的极端天气气候事件变化的最新认知

Latest understanding of extreme weather and climate events under global warming and urbanization influences

近年来,城市气候变化问题引起高度关注。综合IPCC第一工作组第六次评估报告(IPCC AR6)关于气候变暖背景下城市对极端天气气候事件影响的评估,本文得到以下科学认识:城市化加剧了局部气候变暖,全球许多城市都面临更多更强的高温热浪事件;城市化使得诸多城市区域及其下风向极端降水增加,地表径流加强;沿海城市受到日益加剧的与海平面上升有关的复合型洪水的影响;城市污染物排放和不利通风的建筑结构加剧了区域污染,同时增加了地表的臭氧含量。预计未来城市极端高温、极端降水及有关洪水事件将更为频发,空气污染形势更为严峻,气候变化风险进一步加大。中国城镇化进程迅速,需要进一步加强气候变化背景下城市极端事件的观测、形成机理和数值模拟研究,以提升城市极端事件风险认识水平和应对能力。

In recent years,urban climate change has received great attention.This paper synthesizes IPCC AR6WGI assessment on urbanization influence on extreme weather and climate events in context of global climate change.The new understanding are summarized as follows:Urbanization has exacerbated local warming,thus large cities are facing more severe heat waves;More extreme precipitation events are observed in many urban areas and their downwind direction,resulting in increased surface runoff;Coastal cities are affected by increasing compound flooding related to sea-level rise;Urban pollutant emissions and building structures with unfavorable ventilation have enhanced regional pollution and increased surface ozone concentration.In the future,extreme temperature,extreme precipitation and air pollution are projected to occur more frequently and intensified in cities,thus lead to increased risks of climate change.Considering the rapid progress of China in urbanization,it is necessary to further strengthen observation network,mechanism study and numerical simulation for urban extreme events under global warming,thus to improve our understanding and enhance response capabilities in coping with urban extreme events.