Enhanced Trans-Seasonal ENSO Impact on East Asian-Western Pacific Climate in Warmer Future: An Emergent Constraint From Multi-Large Ensembles

Abstract

Predicting the boreal summer climate over East Asia and the western Pacific is crucial for communities preparing for extreme events. A key source of predictability is the strong connection between the western North Pacific anomalous circulation (WNPAC) and the preceding El Niño-Southern Oscillation (ENSO). However, the potential change of this link under future greenhouse warming remains uncertain due to substantial internal variability and inter-model discrepancies. Here, by leveraging emergent constraints from multi-large ensemble simulations, we show that the trans-seasonal ENSO-WNPAC correlation robustly strengthens under high-emission scenarios, with a 67% reduction in the projection uncertainty. This enhancement indicates a 9% increase in the ENSO-contributed predictability (explained variance) of summer WNPAC. The spread across models primarily derives from their differing representations of ENSO-decaying regimes. Our results indicate a more predictable East Asian-western Pacific summer climate in a warmer world, offering encouraging prospects for adapting to anticipated increases in extremes associated with WNPAC.