Extreme weather events in agriculturally important regions in the Bay of Bengal

The Bay of Bengal is one of the most densely populated regions globally, bordered by India, Bangladesh, and Myanmar. Its coastal zones represent critical hotspots from both societal and agricultural perspectives. Major river deltas, including those of the Brahmaputra and Ganges in Bangladesh, the Mahanadi in India, and the Ayeyarwady in Myanmar, provide essential freshwater resources that sustain highly productive agricultural systems and support large local populations. However, ongoing climate change is increasingly associated with extreme weather conditions, such as elevated temperatures, prolonged droughts, and intense precipitation events.

To investigate how climate change at different time horizons and levels of warming influences these extremes, we conducted five regional climate simulations using the Weather Research and Forecasting (WRF) model at 5km horizontal spacing. One simulation represents a 30-year reference period (1981–2010). Two additional simulations cover the mid-21st century (2031–2060) under the SSP2-4.5 and SSP5-8.5 scenarios, respectively. The remaining two simulations represent the late 21st century (2071–2100) under the same SSP2-4.5 and SSP5-8.5 emission pathways.

The results indicate a substantial increase in extreme heat across all river deltas. The number of days exceeding 40 °C is projected to double under SSP2-4.5 and to triple under SSP5-8.5 by the end of the century. Drought frequency increases markedly, with the number of drought events projected to quadruple under both scenarios. Concurrently, extreme precipitation, measured by the RX5 index, shows significant increases in the Ayeyarwady and Brahmaputra deltas. The combined effects of intensified heat stress, more frequent droughts, and increasingly severe precipitation events present major challenges for both local populations and agricultural systems, potentially increasing the risk of displacement in these vulnerable regions.