Anthropogenic Influence Has Increased the Nighttime Heat Stress Risks in Eastern China

Nights with high temperatures and humidity often bring more fatal consequences during the human sleeping process. A significantly increasing trend in the intensity and frequency of humid-heat nights has been observed in eastern China from 1961 to 2014. Detection analyses show that the fingerprinting of anthropogenic forcing, in which the greenhouse gas forcing is critical, can be identified for changes in the humid-heat nights in eastern China. However, the roles of anthropogenic aerosols and external natural forcings cannot be detected, and their effects on the observed changes in humid-heat nights over eastern China are generally negligible. Under different warming scenarios, there is a projected continuation of increasing intensity and frequency of humid-heat nights, although the magnitudes are reduced after constraining. In eastern China, the areal mean intensity of humid-heat nights is projected to increase by approximately 0.9, 1.5, 2.5, and 3.5°C (relative to 1995–2014) for 1.5, 2.0, 3.0, and 4.0°C global warming, while the occurrence of extreme humid-heat night is 1.1, 1.2, 1.2, and 1.3 times more than the current period. Moreover, the population exposed to humid-heat nights in eastern China, particularly in the northern regions, is expected to increase in the future. Our results enhance the understanding of the potential risks of humid-heat nights, which is critical for climate-change policy in China.