Heatwaves on the Rise: The Role of El Niño-Southern Oscillation and Local Water-Energy Exchanges in Shaping Global Patterns

Large-scale and intense heatwaves pose significant risks to ecosystems and human society due to associated heat and water stress. Heatwaves can be classified as daytime, nighttime, and compound, depending on their occurrence time. However, the factors shaping global spatiotemporal patterns of heatwaves remain poorly understood, especially regarding links to large-scale climate mode and local water-energy (LWE) exchange. Here, we analyzed the frequency and intensity of these three heatwave types from 1980 to 2022 using ERA5L air temperature data and examined their associations with the El Niño–Southern Oscillation (ENSO) and LWE-related factors through the LSTM model. Our results show a significant global increase in all types of heatwaves. Compound heatwaves exhibited higher annual frequency and intensity than individual daytime or nighttime events. The three types of heatwaves displayed distinct associations with El Niño and La Niña episodes, with the tropics experiencing the most frequent and intense heatwaves during El Niño years. Meanwhile, terrestrial LWE exchange significantly influenced heatwave development, with stronger effects in dryland and temperate zones than in continental and polar regions. These findings highlight the importance of ENSO and LWE exchanges in shaping heatwave patterns and suggest that future forecasts should consider the temporal evolution and fluctuations in heat accumulation to improve accuracy and reliability.