Strong tropical cyclones have a more gradual increase trend through interaction with ocean subsurface

Understanding changes in global tropical cyclone (TC) intensity and their long-term trends is critical for enhancing societal resilience. Given their disproportionate impacts, shifts in strong TCs, which are defined here as Category 4 and above, are of particular concern. We examined long-term trends in the lifetime maximum intensity (LMI) of strong global TCs and found that their increasing trend is only 43% of the average across all TCs. This discrepancy points to a wind-dependent negative feedback mechanism that restricts the intensification of strong TCs. Further analysis identified enhanced interaction between strong TCs and the deep ocean subsurface as the key driver. Stronger winds induce more intensive mixing and a deeper mixed layer depth (MLD), entraining cold subsurface waters that strongly constrain TC intensification. Our findings highlight the need to improve understanding of intense TC feedback mechanisms to enhance future intensity projections, which is critical for mitigating societal and environmental impacts.