Models predict that extreme precipitation in East Asia could remain intensified even after CO₂ reduction, revealing unexpected climate hysteresis. This persistence, observed in advanced simulations, challenges the idea that decreasing emissions would immediately return rainfall extremes to normal.
What the study reveals
Researchers found that when CO₂ elimination scenarios are imposed, extreme rainfall events do not simply follow the reverse path of warming. Instead, maximum rainfall intensity remains high during the cooling phase, creating a feedback loop where climate retains a memory of its warm past. This hysteresis is most pronounced during the monsoon season, when convective systems are already near saturation.
Effects are not uniform across the Asian basin. North China's heavy rainfall shows a more pronounced increase, while South Korea and Japan show a more moderate but persistent response. This heterogeneity reflects topographical differences, proximity to the sea, and local variations in atmospheric humidity, factors that amplify or attenuate the response to CO₂ concentration changes.
Results are robust across several forecasting systems, including ECMWF model, Copernicus products, and machine learning platforms like GraphCast and Pangu-Weather. The convergence of conclusions between these models, which use neural networks to improve spatial resolution, strengthens confidence in the reality of this hysteresis phenomenon.