Increasing global heatwave occurrence associated with land-atmosphere interactions

Abstract Marked increases in heatwave frequency and intensity under global warming threaten ecosystems and societies. While large-scale atmospheric circulation has been considered the dominant influence, the role of land-atmosphere coupling remains unclear. Using ERA5 reanalysis data (1980–2022), we analyze the spatiotemporal evolution of heatwaves and assess soil moisture (SM) and sensible heat flux (SH) anomalies during the two days preceding onset. Most heatwaves occur under the NP (negative SM and positive SH anomalies) state. In 93.41% of global land areas, heatwaves occur most frequently under the NP state, while in 69.53% of land areas, heatwave frequency increases most rapidly under the NP state. Compared with 1980–2000, NP-state heatwaves increased by 5.21 events per decade during 2002–2022, with frequency doubling in 87.29% of land areas. Nearly 7% of land shifted from other states to NP dominance. These results highlight a close association between land-atmosphere coupling and heatwave occurrence.