Global Increase in Tropical Cyclone Rapid Slowdown Events in Offshore Regions

Rapid slowdown (RS) of tropical cyclone (TC) motion in offshore regions poses an increased threat to coastal populations and economies due to its unexcepted nature and prolonged exposure. However, the variations of global RS events in offshore regions remain poorly understood. Here, we show that, unlike open oceans where RS counts show no significant changes, offshore areas within 400 km of the coastline have experienced a fourfold increase in RS events from 1982 to 2023. Both the global sea surface temperature and Pacific decadal oscillation contribute to this trend, through producing favorable environmental conditions—namely reduced vertical wind shear and increased potential intensity. Climate model simulations suggest that global ocean warming has intensified these changes. Moreover, RS events are significantly correlated with the rapid intensification within the coastal regions. These findings underscore the increasing threat of RS in coastal regions over the recent decades, which may continue under a warming climate.