Severe Socioeconomic Exposures Due to Enhanced Future Compound Flood-Heat Extreme Hazards in China

As the climate warms, a new hazard, compound flood-heat extreme (CFH) events, characterized by the rapid succession of devastating floods and deadly heat (or vice-versa), are becoming increasingly frequent, threatening infrastructure and ecosystems. However, how this CFH hazard will change under future anthropogenic warming in China and their potential population and economic exposures remains unexamined. Here, we systematically quantify the projected changes in bivariate CHF hazards for 187 catchments in China during the 2071–2100 period relative to the 1985–2014 period and investigate the potential population and gross domestic product (GDP) exposure, by developing a climatic-hydrological-socioeconomic modelling chain. We find that there is a nationwide increase in CFH hazards and the historical 30-year CFH episodes are projected to increase by 10 times in southern catchments. Under the synergistic impacts of changing CFH episodes and population (GDP), a mass of people in southern (0.79–2.13 thousand/km2) and eastern (1.68 thousand/km2) catchments and an enormous sum of GDP in eastern catchments (400–912 million/km2) will be exposed to increasing CFH hazards. Our results highlight the necessity of improving both societal resilience and mitigation solutions to address such weather-related hazards.