Divergent Risks of Dry and Wet Heat Waves Across China: Historical Trends and Future Projections

Abstract

Heat waves have been intensifying with climate change, presenting a growing risk to human health and ecosystems. However, the differential impacts of dry versus wet heat waves and their future trajectories remain underexplored. Here, we introduce a data-driven approach to classify heat waves by relative humidity, revealing dry heat waves predominantly affect China's arid northwest, while wet heat waves are more prevalent in its humid south. These events' frequency and persistence have increased substantially over recent decades. Under a high socioeconomic scenario, the intensified dry and wet heat waves will continue expanding, with increases of approximately 141% ± 48% and 224% ± 59% by the 21st century's end. Population exposure to wet heat waves is projected to increase by about 100% ± 36%, nearly doubling that of dry heat waves, with North China facing the highest risks. By then, an estimated 10% and 40% of China's population will face exposure to dangerous dry and wet heat waves. Adopting a moderate socioeconomic development pathway could substantially mitigate these risks. Our findings indicate that climate change is reshaping these heat wave threats, necessitating targeted adaptation strategies to address these evolving challenges.