Abstract
Early-season tropical cyclones (TCs), particularly in the pre-monsoon period (April–June) of the North Indian Ocean (NIO) basin, often cause exceptionally severe damage to populated landmasses despite being less frequent. A critical uncertainty is how these TCs respond to anthropogenic climate change. Here, we find a significant increasing trend in pre-monsoon TC activity in the NIO basin, with accumulated cyclone energy exhibiting a striking rise of 3.01 × 104 knots2 per decade (P < 0.05) during 1981–2023, while the corresponding trend during the post-monsoon season (October–December) is weaker and insignificant. Climate models identify increased greenhouse gas as the primary driver, creating more favorable thermodynamic conditions for TC formation and maintenance in the NIO basin during the pre-monsoon season. These enhanced thermodynamic conditions are projected to intensify further, suggesting the increasing trend in pre-monsoon TC activity may continue to accelerate in the future.
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Data availability
TC data are obtained from the IBTrACS (https://www.ncei.noaa.gov/products/international-best-track-archive). The ERA-5 reanalysis data are available at https://cds.climate.copernicus.eu/datasets/reanalysis-era5-single-levels-monthly-means?tab=overview. The raw outputs of CMIP6 models are available at available at https://esgf-node.llnl.gov/search/cmip6/.
Code availability
Code for figure plotting can be obtained at https://zenodo.org/records/18477970.
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Acknowledgements
This research is supported by the Young Elite Scientists Sponsorship Program by China Association for Science and Technology under grants No. 2023QNRC001 (Kaiyue Shan), and National Natural Science Foundation of China (NSFC) under grants No. 41961144014 (Xiping Yu) and No. 42175029 (Fengfei Song).
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K.S. and X.Y. designed the research. K.S. performed the analysis, drew all the figures and wrote the first draft of the paper. K.S., F.S., Y.L., P.-S.C., L.W., and X.Y. provided comments on different versions of the paper.
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Shan, K., Song, F., Lin, Y. et al. Global warming drives an increase in pre-monsoon tropical cyclone activity over the North Indian Ocean. Nat Commun (2026). https://doi.org/10.1038/s41467-026-69818-x
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DOI: https://doi.org/10.1038/s41467-026-69818-x
