Western North Pacific tropical cyclone activity modulated by phytoplankton feedback under global warming

The effects of bio-optical feedback through chlorophyll on future tropical cyclone (TC) activity are not well understood. Here we use Earth system model simulations with the biogeochemical feedback turned on and off to investigate the influence of chlorophyll changes on projections of TCs over the western North Pacific (WNP). An increase in chlorophyll in the tropical eastern Pacific and a decrease in the tropical western Pacific lead to a La Niña-like sea surface temperature warming. This pattern plays a crucial role in enhancing the genesis potential index over the southeastern WNP by 10.16% through strengthening of the Walker and local Hadley circulations. The enhanced genesis potential index is further supported by an additional higher-resolution atmospheric model experiment that shows a 71% increase in TC genesis over the southeastern WNP (from 2.00 to 3.43 yr⁻¹) and a 27.02% enhancement in TC landfall frequency in East Asia (from 4.33 to 5.50 yr⁻¹).