East Asian heatwaves intensify faster than they dissipate in a warming climate

Abstract Extreme heat research has primarily emphasized static characteristics, while the temporal evolution of heatwaves remains less explored. Using observations (1979–2024) and CMIP6 simulations, we quantify heatwave lifecycle dynamics across East Asia in terms of onset and decay rates. Heatwaves consistently intensify faster than they dissipate, with stronger asymmetry at higher latitudes. Future changes depend strongly on how extremes are defined. Under a fixed-baseline framework, both onset and decay rates increase with warming, primarily associated with increasing peak temperatures. In contrast, using a moving-baseline substantially reduces these increases in mid-latitudes, demonstrating that projected heatwave lifecycle changes are sensitive to the evolving climate reference state and may involve changes in climate variability and atmospheric circulation processes. These results highlight the importance of the climate reference framework when interpreting how heatwave lifecycle characteristics may change under continued warming.