The increase in hot–dry events with a high risk of mortality in China associated with the phase transition of the Atlantic Multidecadal Oscillation

Compound extreme climate events involving multiple meteorological elements usually have a more severe impact on the environment and human health than single-element extreme events. However, the current definition of multi-element compound extreme events is proposed from meteorological and statistical perspectives, without integrating health data, making the conclusions less practical for guiding health risk prevention. This study identified the threshold for hot–dry compound extreme events with high mortality risks (HMHDs) in China, using daily mortality data and temperature–humidity data from 278 districts or counties, and explored the interdecadal change and driving mechanisms of HMHD frequency in China from 1979 to 2021. The results show a significant increase in annual HMHD frequency in China after 2000, mainly occurring in summer (June, July, August). The northwestern to western regions of China (Xinjiang, Inner Mongolia, Gansu), and from the southwestern to the areas south of the Yangtze River (Sichuan, Hubei, Hunan, Jiangxi, Fujian, Guizhou, Yunnan), experience an increase of >10 days. The authors find that the interdecadal abrupt change in HMHD frequency can be attributed to the shift of the Atlantic Multidecadal Oscillation from a negative to a positive phase by affecting the Silk Road teleconnection.

摘要

目前对复合极端事件的定义主要从气象和统计学角度出发, 未能结合健康数据, 使相关研究在指导健康风险预防方面的实用性较差. 本研究利用中国死亡数据和温湿度数据, 识别了中国高死亡风险的复合极端干热事件 (HMHDs) 的阈值, 并探讨了HMHD频率的年代际变化及其驱动机制. 结果显示, 中国西北地区, 西南地区和江南地区的HMHD频率平均每年都超过10 天. 2000年后, 中国HMHD频率显著增加, 主要发生在夏季. 驱动机制分析表明, HMHD频率的年代际变化可以归因于大西洋多年代际振荡由负相位转变为正相位. 本研究可为气候变化导致的健康风险防控提供参考依据.