Future changes and uncertainty in tropical cyclone genesis over the western North Pacific: insights from the dynamic genesis potential index using CMIP6 models

Changes in tropical cyclone (TC) genesis over the western North Pacific (WNP) remain uncertain due to challenges in accurately simulating TC formation in climate models. As an alternative approach, this study investigates future changes in the newly proposed dynamical genesis potential index (DGPI) over the WNP to infer future TC genesis using the Coupled Model Intercomparison Project Phase 6 (CMIP6) models. Under the shared socioeconomic pathways (SSP) 585 scenario, DGPI projections reveal negative anomalies in the tropical western and central WNP but positive anomalies in the subtropical WNP and tropical eastern WNP. These changes suggest an eastward and poleward shift in TC genesis locations. However, the opposing DGPI anomalies across regions largely offset each other, resulting in minimal basin-wide changes in DGPI. The El Nino-like sea surface temperature (SST) and subtropical north Pacific SST warming pattern collectively contribute to the anomalous DGPI distribution by modifying the Walker circulation and the subtropical meridional temperature gradient. The projections also exhibit substantial uncertainty in both basin-wide magnitude and spatial distribution, linked to the diversity in tropical and subtropical SST patterns across the North Pacific. These findings identify key changes in large-scale dynamical conditions and their associated uncertainties, providing critical insights for understanding future WNP TC activity under warming scenarios.