Fewer, but More Intense, Future Tropical Storms Over the Ganges and Mekong Basins.

Understanding climate change impacts on Tropical Storm (TS) activity is crucial for effective adaptation planning and risk assessment, particularly in densely populated low‐lying delta rivers basins like the Ganges and Mekong. The change to TS characteristics with warming is uncertain due to limitations in global climate model resolution and process‐representation and storm tracking algorithms (trackers). Here, we used 13 HighResMIP models and two trackers to estimate the uncertainty in projections of TS characteristics. We found different trackers producing qualitatively similar but quantitatively different results. Our results show a decline (median ∼52%) in the frequency of TS but increase in the strongest TS and Available Cyclone Energy (ACE) of TS over both basins. The higher‐resolution models extract TS with much higher intensity and ACE values compared to the lower‐resolution models. These results have implications for adaptation planning and risk assessment for TS and suggest the need for further high‐resolution modeling studies. Plain Language Summary: Tropical Storms (TS) are one of the world's most damaging natural hazards which result in colossal socio‐economic losses to life, infrastructure, and property, especially in low‐lying delta rivers basins like the Ganges and Mekong. Knowledge of changes to TS activity under climate change can therefore be helpful in better disaster risk mitigation and climate adaptation. Previous modeling studies have used coarse‐resolution global climate models unable to capture key TS characteristics. In this study, we utilized finer resolution (up to ∼25 km at six hourly time‐steps) CMIP6 HighResMIP models and two different tracking algorithms (trackers) to resolve a part of this uncertainty. Our results project a decline to the frequency of future TS but an increase in the strength of TS (in terms of intensity and Available Cyclone Energy, qualitatively similar for both trackers). These findings can be used to assess the future resilience of existing infrastructure systems to Tropical Storms across these densely populated basins. Key Points: We used multiple CMIP6 HighResMIP models and two trackers to estimate the change in the Tropical Storms (TS) characteristics over the Ganges and Mekong basinsOur results show a decline in the future frequency of TS but increase in the future intensity and Available Cyclone Energy of TS over both basinsBoth tracking algorithms produce qualitatively similar but quantitatively different results [ABSTRACT FROM AUTHOR]