South India has grown wetter over 70 years: study
A study by the India Meteorological Department and the Indian Institute of Tropical Meteorology, Pune, finds south India has become wetter. The hot semi-arid area nearly halved over 70 years. Much of it is now tropical savannah. Read it to revise the Köppen climate types and India’s climate regions.
- Hot semi-arid area
- 30% → 16%
- Savannah share
- About three-fourths
- Periods compared
- 1951-80 vs 1991-2020
- Journal
- MAUSAM
South India’s climate shift: what happened?
Map books show large dry zones in the Deccan. A new study says those maps need to be redrawn.
- The ‘hot semi-arid’ area nearly halved, from about 30% to 16% of the peninsula.
- Much of it is now tropical savannah: more rain, but a long dry season.
- Savannah now covers nearly three-fourths of peninsular India, up from about three-fifths in the 1950s.
- The study was published in MAUSAM, the Department’s journal.
What is the Köppen climate classification?
The Köppen scheme divides the world into climate types using rainfall and temperature.
In India, ‘Aw’ is tropical savannah, ‘BSh’ is hot semi-arid steppe, and ‘Am’ is tropical monsoon.
The study used the Köppen-Geiger version on data from 1951-1980 and 1991-2020.
Hot semi-arid vs tropical savannah
| Point | Hot semi-arid (BSh) | Tropical savannah (Aw) |
|---|---|---|
| Rain | Low | More |
| Dry season | Very long | Long, but with wet summer |
| Share of peninsula then | About 30% | About three-fifths |
| Share now | 16% | About three-fourths |
Which laws and Articles apply?
- India Meteorological Department: under the Ministry of Earth Sciences.
- Indian Institute of Tropical Meteorology, Pune: under the Ministry of Earth Sciences.
- Köppen-Geiger scheme: rainfall and temperature based.
- National Action Plan on Climate Change: includes a mission on sustainable agriculture.
Why does south India’s changing climate matter?
| Angle | What to note |
|---|---|
| Geography | Climate maps of India may change. |
| Agriculture | Crop choices depend on rain. |
| Water | More rain but long dry spells. |
| Climate change | Shows long-term regional shifts. |
What are the problems with south India’s changing climate?
- Long dry seasons still stress farms.
- Extreme rain can cause floods.
- Old crop plans may not fit new zones.
- Local data gaps remain.
What should be done next on south India’s changing climate?
- Update agro-climatic zone maps.
- Advise farmers on new crop patterns.
- Store more rainwater.
- Study district-level changes.
What can Prelims ask on south India’s changing climate?
Prelims probability: Expect a question on Köppen climate types, especially the features of the tropical savannah climate.
- Köppen ‘Aw’: tropical savannah.
- Köppen ‘BSh’: hot semi-arid.
- IMD and IITM: under the Ministry of Earth Sciences.
- MAUSAM: IMD’s journal.
- Savannah climate: wet summer, long dry winter.
How to write about south India’s changing climate in Mains
Practice question (15 marks, 250 words): Discuss how changing climate zones in peninsular India could affect agriculture and water management.
- Intro: IMD-IITM study.
- Köppen shift.
- Impact on farms and water.
- Adaptation steps.
- Conclusion: plan with the new map.
Ready lines for your answer
- The map of India's climate is being redrawn by the climate itself.
- Plan farms for the climate we have, not the one we had.
Quotable data pointHot semi-arid area fell from about 30% to 16% of the peninsula.
Photo: T. R. Shankar Raman, CC BY-SA 3.0, via Wikimedia Commons
Exam angle
Prelims: Köppen types. · Mains GS-I: Indian climate.
Practice MCQs
Original practice questions (not PYQs).
In the Köppen climate classification, the tropical savannah climate, which now covers about three-fourths of peninsular India, is shown by which symbol?
Answer (c) & explanation
Aw is the tropical savannah climate, with a wet season and a long dry winter. Am is tropical monsoon, BShw is semi-arid steppe and Cwg is monsoon type with dry winters.
Which of the following regions receives a large part of its annual rainfall from the north-east monsoon during October to December?
Answer (d) & explanation
Tamil Nadu's Coromandel coast lies in the rain shadow of the south-west monsoon and gets much of its rain from the north-east monsoon in October to December.
Questions students ask about this
What did the study find?
South India has become wetter; the hot semi-arid area nearly halved.
What is tropical savannah climate?
A climate with good summer rain but a long dry season, Köppen type 'Aw'.
Which periods were compared?
1951-1980 and 1991-2020.
Who did the study?
The India Meteorological Department and the Indian Institute of Tropical Meteorology, Pune.