This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A research team at The Hong Kong Polytechnic University (PolyU) has found that the area affected by tropical cyclone (TC) rainfall is extending inland along Northern Hemisphere coasts at an average rate of approximately 3.8 kilometers (2.4 miles) per decade. Driven by rising nearshore sea surface temperature (SST), this shift is increasing disaster risks for inland regions.
The work is published in the journal Nature Communications. While extensive research has examined TC rainfall intensity, accumulation and frequency in a warming climate, comprehensive global-scale quantitative analysis of whether the area affected by TC rainfall is extending inland and the role of nearshore SST warming in this shift has remained limited. To address this gap, Yi-Qing Ni, Yim, Mak, Kwok & Chung Professor in Smart Structures and chair professor of smart structures and rail transit in the PolyU Department of Civil and Environmental Engineering, together with research fellow Dr.
E Deng and their research team, analyzed global TC and rainfall data from 1980 to 2023. Combining these data with numerical simulations and climate model analyses, the team assessed trends in the inland extension of TC rainfall. Ni said, "Our research shows that heavy TC rainfall, defined as at least 30 millimeters (1.2 inches) within three hours, is extending farther inland along Northern Hemisphere coasts at a rate of approximately 3.8 ± 1.8 kilometers (2.4 ± 1.1 miles) per decade, affecting areas more than 100 kilometers (62 miles) from the coastline.
These areas have historically been less affected by such disasters and often lack adequate flood protection infrastructure and emergency preparedness. Comprehensive measures to strengthen disaster preparedness and infrastructure planning should therefore be taken as soon as possible." The team found a close relationship between the inland extension of heavy TC rainfall and rising nearshore SST. Experiments using the Weather Research and Forecasting model showed that warmer nearshore waters increase moisture in the lower atmosphere while strengthening differences in airflow between land and sea.
These changes alter atmospheric conditions from coastal to inland areas after TC landfall, making it easier for heavy rainfall to persist and develop farther inland. The study also found that when the influence of nearshore SST warming was statistically removed from the data analysis, the trend toward inland extension of heavy TC rainfall almost entirely disappeared, highlighting the critical role of ocean warming. Analysis of global climate simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6), coordinated by the World Climate Research Programme, indicated that the warming trend in nearshore SST is primarily associated with human-induced greenhouse gas emissions.
The inland extension of heavy TC rainfall is particularly evident in the western North Atlantic, the Bay of Bengal and the western North Pacific. Stronger signals were also identified in the southeastern United States, southeastern Mexico, eastern and southeastern India, Bangladesh, eastern and southeastern China, and the Indochina Peninsula. These findings highlight the need to more closely monitor changes in TC-related flood risks affecting inland communities and infrastructure in these regions.
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