Full Breakdown
India Meteorological Department (IMD) Study Maps Seven-Decade Climate-Zone Shifts Across India
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Core Findings
- Northwest India: The hot semi-arid zone grew from roughly 25 % (1951-1980) to about 33 % (1991-2020), pushing the dry zone eastward into Uttar Pradesh and cutting the temperate zone to under 20 %.
- Southern Peninsula: The hot semi-arid zone fell from ?30 % to 16 %, while tropical savannah now covers three-quarters of the peninsula.
- Maharashtra Interior: Marathwada and west Vidarbha moved from tropical savanna to hot semi-arid, driven by rising temperatures.
- Coastal West: The tropical monsoon zone expanded along the Konkan, Goa, coastal Karnataka and Kerala.
- Gangetic West Bengal & Northeast: These areas shifted from tropical savannah to temperate; the temperate zone now exceeds 80 % of the northeast, up from three-quarters.
- Rainfall Trends: Southern India saw increased rainfall, while the northern plains recorded declines, with notable deficits in West Bengal and Bihar over four decades.
Data & Statistics
- About 7 % of the northwest region moved into the drier zone as temperatures rose and rainfall fell.
- Maharashtra’s 2023 monsoon had a 19 % rainfall deficit, compared with a national shortfall of 12.6 % linked to El Niño.
- The state declared drought in 265 of its 358 talukas on September 26.
- In the northeast, the tropical savannah’s share dropped from ?18 % (1951-1980) to 12 % (1991-2020).
Official Statements & Responses
- Rajib Chattopadhyay, Indian Institute of Tropical Meteorology (IITM) co-author, noted that declining rainfall in Gangetic West Bengal and Bihar aligns with the North Pacific “Victoria Mode” pattern and that both seasonal and long-term trends should inform forecasts.
Why It Matters
- Climate-zone shifts affect crop suitability, sowing windows and irrigation, threatening paddy production in the north and interior Maharashtra.
- The recent drought in Maharashtra’s interior coincides with the identified shift toward hotter, drier conditions, highlighting the need for region-specific agricultural strategies.
- Long-term rainfall changes raise food-security concerns for millions of farmers across the affected zones.
Conflicting Reports & Gaps
- Sources agree on the direction of climate-zone changes but note that the study does not establish a causal link between the long-term shift and the 2023 drought, leaving a gap in understanding how seasonal failures interact with the evolving climate backdrop.
Verbatim Quotes
- “When we compared India’s climate map decade by decade from 1951 to 2020, the clearest change was in the north, where the hot, dry zone has pushed east into Uttar Pradesh, and because this is one of the country’s most important farming regions, the timing of sowing and harvesting there needs to be watched closely,” — Ananya Karmakar, lead author
- “This year’s drought in Marathwada and Vidarbha is an El Niño drought, and our study does not look at individual seasons, but it does show that Marathwada and west Vidarbha now lie in a hotter, drier climate zone than they did in the 1960s, so a failed monsoon like this one lands on a climate that has itself shifted, and water and farm planning in the region has to account for that,” — Ananya Karmakar, lead author