Substantial Increase in the Joint Occurrence and Human Exposure of Heatwave and High‐PM Hazards Over South Asia in the Mid‐21st Century
Substantial Increase in the Joint Occurrence and Human Exposure of Heatwave and High‐PM Hazards Over South Asia in the Mid‐21st Century
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DOI：
10.1029/2019av000103
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发表时间：
2020-04
期刊：
影响因子：
8.4
通讯作者：
Xiaokang Wu;Yangyang Xu;R. Kumar;M. Barth;C. Diao;Meng Gao;Lei Lin;B. Jones;G. Meehl
中科院分区：
文献类型：
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作者：
Xiaokang Wu;Yangyang Xu;R. Kumar;M. Barth;C. Diao;Meng Gao;Lei Lin;B. Jones;G. Meehl
在过去的几十年里，世界范围内的极端高温事件有所增加。如果不积极减少温室气体排放，将导致极端高温的频率和强度大幅增加。与此同时，许多城市正面临严重的空气污染问题，其特点是高PM时段持续数天至数周。基于对再分析有偏差的最新区域化学气候模式进行的高分辨率十年十年模式模拟，我们在这里表明，当日平均湿球温度为25℃作为严重健康影响的阈值时，在RCP8.5情景下，南亚地区的极端高温平均频率从1997-2004年的45±5天/年增加到2046-2054年的78±3天/年。以每天平均60μg/m~3的PM2.5日平均浓度作为这种“不健康”极端的阈值，在RCP8.5下的2050年期间，高PM极端将出现132±8天/年。更令人担忧的是，由于两个应激源同时作用对健康的潜在影响，热浪和高PM危险(HHH)同时发生，频率将大幅增加175%，持续时间将增加79%。这与单独评估热浪或高PM时73-76%的增长形成了鲜明对比。2050年，暴露于长期HHH的土地比例增加了10倍以上。在短短几十年内令人震惊的增长给适应带来了巨大的挑战，需要更积极的缓解。例如，在较低的排放路径下，HHH的频率仅增加58%，而高PM极值的频率较低。
Extreme heat occurrence worldwide has increased in the past decades. Greenhouse gas emissions, if not abated aggressively, will lead to large increases in frequency and intensity of heat extremes. At the same time, many cities are facing severe air pollution problems featuring high‐PM episodes that last from days to weeks. Based on a high‐resolution decadal‐long model simulation using a state‐of‐the‐science regional chemistry‐climate model that is bias corrected against reanalysis, here we show that when daily average wet‐bulb temperature of 25 °C is taken as the threshold for severe health impacts, heat extremes frequency averaged over South Asia increases from 45 ± 5 days/year in 1997–2004 to 78 ± 3 days/year in 2046–2054 under RCP8.5 scenario. With daily averaged PM2.5 surface concentration of 60 μg/m3 defined as the threshold for such “unhealthy” extremes, high‐PM extremes would occur 132 ± 8 days/year in the Decade 2050 under RCP8.5. Even more concerning, due to the potential health impacts of two stressors acting in tandem, is the joint occurrence of the heatwave and high‐PM hazard (HHH), which would have substantial increases of 175% in frequency and 79% in duration. This is in contrast to the 73–76% increase for heatwave or high PM when assessed individually. The fraction of land exposed to prolonged HHH increases by more than tenfold in 2050. The alarming increases in just a few decades pose great challenges to adaptation and call for more aggressive mitigation. For example, under a lower emission pathway, the frequency of HHH will only increase by 58% with a lower frequency of high‐PM extremes.