The 2025 Southeast Asian extreme rainfall: role of anthropogenic climate change

This study investigates the role of anthropogenic climate change in the record-breaking extreme rainfall of November 2025 that affected northern Sumatra (Indonesia), Peninsular Malaysia, and southern Thailand. Using event attribution methods based on the Weather Research and Forecasting (WRF) model and a pseudo-global warming approach, the authors simulated 36 ensemble runs under four climate states (pre-industrial, present, mid-future, and late-future) with climate signals derived from an 11-model Coupled Model Intercomparison Project Phase 6 (CMIP6) ensemble. Gridded precipitation analysis relied on the Multi-Source Weighted-Ensemble Precipitation (MSWEP) dataset, and tropical cyclone tracks were obtained from the International Best Track Archive for Climate Stewardship (IBTrACS) database.

The study finds that climate change since the 1850s has significantly increased the intensity of this rainfall event, with present-day and future climates projecting further intensification. Super-scaling rates in rainfall—up to three times higher than thermodynamic expectations—were identified for southern Thailand, northeastern Peninsular Malaysia, and northern Sumatra. The authors recommend future research should include deeper analysis of cyclone dynamics under warming, greater accessibility of ground-based rainfall observations in Southeast Asia, reduction of model uncertainties especially in convection and microphysics, and integration of hydrological and landslide modeling to directly link projected rainfall changes to risks of flooding and slope instability.