Anthropogenic forcing dominates changes in compound long-duration dry and heat extremes in China

In the context of global warming, the adverse impacts of compound dry and heat extremes (CDHEs) on human societies, ecosystems, and economies surpass those of single drought or heat extremes. This study investigates the trends of CDHEs in China from 1961 to 2014, meticulously analyzing key indicators including frequency, duration, high-temperature intensity, and total number of days. Through model simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6), we attribute the changes in CDHEs to various external driving factors. We have also assessed the projected variations in CDHEs under the low, medium, and high emission scenarios of the Shared Socioeconomic Pathway (SSP1-2.6, SSP2-4.5, and SSP5-8.5). CDHEs in China are predominantly concentrated in northeastern, central, and eastern regions of China, with all four indicators of CDHEs exhibiting increasing trends in most regions of China over the past 54 years. The impacts of anthropogenic forcing dominate the changes in CDHEs over China, especially over the northwest and southwestern regions where anthropogenic forcing can increase the probability of the occurrences of CDHEs by 1.3 times (range 1.2–1.5). Up to 40% of the occurrence of CDHEs in China can be attributed to anthropogenic forcing. Moreover, the impacts of anthropogenic forcing on CDHEs are higher for the extreme ones identified with more strict thresholds than the moderate ones. In the future, under the three scenarios in CMIP6, the occurrences of CHDEs are projected to increase over most of China, with the most substantial increases under SSP5-8.5. The anthropogenic emissions are expected to exert the greatest impacts on CDHEs over parts of northwestern and southwestern China, accounting for more than 80% of projected CDHEs increases therein in the future under SSP5-8.5.