Human activities increased compound drought and heat events over China during 1961-2014

Compared to independent drought or extreme heat events, compound drought and heat events (CDHEs) can pose more adverse impacts on ecosystems and human society. As the anthropogenic influence on CDHEs in China remains largely unquantified, we analyse both observed and simulated changes in the occurrence of CDHEs over China from 1961 to 2014, and perform detection and attribution analyses utilizing an optimal fingerprinting method, based on observations, reanalysis data and numerical experiments from seven Coupled Model Intercomparison Project Phase 6 (CMIP6) models. Upward trends are found in observed CDHEs during 1961-2014 over the majority of China, especially in the last two decades. The increase in CDHEs is largely attributed to human influence. Anthropogenic forcing is detectable in the observed CDHEs changes in the whole China and its eastern region. Furthermore, a three-signal analysis indicates that greenhouse gases play a key role in increasing CDHEs over China, while natural forcing has a negligible effect. Anthropogenic aerosol emissions also play a detectable role in offsetting the greenhouse gas-induced increase of CDHEs over China. Human influence can be detected in the occurrence of compound drought and heat events (CDHEs) increase over China in 1961-2014, during which greenhouse gas forcing is primary. Anthropogenic aerosol forcing partially offsets the positive role of greenhouse gases on the CDHEs. image