Inhomogeneous aerosol forcing increasing tropical cyclone intensity in western North Pacific by weakening vertical wind shear

Abstract Faced with increasing tropical cyclone (TC) intensity in the western North Pacific (WNP) in recent decades, the simultaneous decrease in vertical wind shear (VWS) has been considered an important contributor. However, anthropogenic contribution to this decreased VWS remains uncertain. Here, we isolate the individual effects of greenhouse gases (GHS), aerosols, natural forcings, and internal climate variability on the decreased VWS over the WNP using multi-model ensemble simulations. We find that Eurasia’s inhomogeneous aerosol forcing triggers a southeastward-propagating wave train from central Europe and a meridional circulation teleconnection over southeastern Eurasia, inducing anomalous westerlies at 200 hPa in the WNP monsoon trough (MT) region. This dominates the weakening of VWS in the MT region, thereby promoting dynamic conditions favorable for increased TC intensity. Given that aerosol emissions in Europe show limited potential for further reduction, future aerosol emissions mitigation in East Asia is expected to intensify VWS over the WNP, thereby dampening the intensification of TC.