East India’s Tropical Climate Zone Shrinks Due to Rising Temperatures: IMD Study
• A recent study by the India Meteorological Department (IMD) and the Indian Institute of Tropical Meteorology (IITM), Pune, has revealed significant shifts in the climate zones of eastern and northeastern India over the past seven decades. Published in the October 2026 issue of the journal MAUSAM, the research analysed temperature and rainfall data from 1951 to
• It found that the tropical savannah climate zone in northeast India has shrunk from 18% of the region in 1951–1980 to 12% in 1991–2020, while the temperate zone expanded to cover over 80% of the area. The study also highlighted a long-term decline in annual rainfall over Gangetic West Bengal and Bihar, attributed to large-scale ocean-atmosphere interactions such as the Victoria Mode and El Niño. These changes are expected to have significant implications for agriculture, water resources, and food security in the region.
Impact & Risks
The shrinking tropical climate zone and declining rainfall pose risks to agriculture, particularly rice cultivation in the eastern Indo-Gangetic plains. Reduced rainfall can disrupt sowing schedules, crop growth, and harvesting, while prolonged water shortages may strain irrigation systems and rural livelihoods. The study also warns of potential impacts on water availability and food security, necessitating adjustments in long-term planning. The 2026 monsoon season recorded a 25.6% rainfall deficit in eastern and northeastern India, with Meghalaya experiencing a 60% shortfall, Bihar 32%, and Assam 28%. These deficits, combined with rising temperatures, could exacerbate vulnerabilities in the region.
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