Deciphering the shift in the dominant type of high-health-risk compound extremes in China

Amid global warming, China, a climate-vulnerable region, faces escalating complexity and frequency of compound extreme events, posing risks to public health. Using ambulance dispatch data of 13 cities from the Chinese Ambulance Service Center and ERA5 meteorological data (1979–2024), this study investigates the dominant type transition of high-health-risk temperature–humidity compound extremes in China. The results show that hot–wet extremes have surpassed cold–wet ones as the dominant type around 2010. Further investigation into mechanisms reveals that winter warming in the Barents–Kara Sea (shift contribution: 37.59%, the same below) and summer Arctic sea-ice melting (33.37%) trigger circulation anomalies via polar–midlatitude teleconnections. Spring European soil moisture anomalies (15.24%) amplify the initial signal through land–atmosphere interactions. These anomalies propagate eastward to East Asia via Rossby wave trains, driving abnormal atmospheric circulation: the western Pacific subtropical high enhanced by the influence of western Pacific sea surface temperature increases summer moisture transport to the Tibetan Plateau (26.25%) and later affects Northeast China in winter (18.92%). These circulatory adjustments directly cause changes in temperature and humidity: 4.06 percentage point increases in relative humidity on the Tibetan Plateau, and 4.42 percentage point increases in Northeast China. Combined with the nationwide warming of 0.53°C, hot–wet events have significantly increased and emerged as the dominant events, with the Tibetan Plateau and Northeast China contributing the most to this shift. This study reveals a multi-sphere synergistic mechanism, providing a scientific basis for health risk prevention and adaptation under climate change. 在全球变暖背景下, 复合极端事件的频率与复杂性持续增加, 对公众健康构成威胁.本研究基于中国急救调度数据和ERA5气象资料, 分析了高健康风险的温湿复合极端事件主导类型的转变.结果发现, 约自2010年起, 湿热型事件已取代湿冷型成为主导类型.机制分析表明, 北极冬季增温与夏季海冰消融通过遥相关引发环流异常, 欧洲土壤湿度异常进一步放大信号.这些异常经罗斯贝波东传, 驱动东亚大气环流调整, 叠加全国气候变暖背景和西太副高增强, 共同促使中国温湿条件发生变化, 湿热事件成为主导类型, 青藏高原和东北地区最为突出.该研究揭示了多圈层协同作用机制, 为气候变化健康风险防控提供了科学依据.