The characteristics and spatiotemporal evolution of heatwaves and droughts across six typical regions in China

Extreme heatwaves and droughts pose critical threats to global water, food, and socioeconomic security. However, comprehensive understanding of their spatiotemporal dynamics, underlying drivers, and cascading impacts remains limited, particularly across China's ecologically vulnerable regions. This study employs GLDAS data, validated against NOAA flux tower observations (R² = 0.97), to analyze heatwave and drought characteristics across six major Chinese basins (2004-2023). Marked increases are observed in frequency (0.019 vs. 0.022 events/yr), intensity (0.012 °C vs. 0.14 mm/yr), duration (0.039 vs. 0.4 days/yr), and earlier onset (0.23 vs. 0.045 days/yr). Under the persistence of current trends, our extrapolation suggests that by 2050, these metrics are projected to increase 1.14-1.33-fold, with onset advancing by 1.22-4.33 days, driven predominantly by anthropogenic forcing. Spatially, the Yangtze Basin exhibits high frequency, the Qinghai-Tibet Plateau high intensity, the Songliao Basin moderate frequency with high intensity, and the Loess Plateau and Pearl Basin frequent shorter events. Northern regions experience persistent warming, while the southeast shows increased precipitation, evapotranspiration, and groundwater and soil moisture. Key correlations include temperature with heatwave intensity, runoff with duration, and food production with heatwave attributes. Drought correlates strongly with precipitation, groundwater, terrestrial water storage, and population growth. Mitigating greenhouse gas emissions is imperative to reduce escalating disruptions across hydrological, agricultural, and societal systems.