UPSC Mains 2024 GS1 Q4: model answer
What is sea surface temperature rise? How does it affect the formation of tropical cyclones?
What the question wants
Define SST rise and explain its effect on cyclone formation and intensity.
How to structure it
Intro: definition and trend. Body: (1) Effect on tropical cyclones: Threshold, Fuel, Rapid intensification, Heavier rain. Conclusion: SST is necessary but not sufficient; shear and moisture also decide.
- 1(1) Effect on tropical cyclones: Threshold
- 2Fuel
- 3Rapid intensification
- 4Heavier rain
Model answer
Sea surface temperature (SST) is the temperature of the ocean's top layer. Oceans have absorbed over 90% of the extra heat from global warming, and the Indian Ocean is among the fastest-warming basins.
Effect on tropical cyclones
- Threshold: cyclones form over water warmer than about 26.5°C; warmer seas widen the area and season of formation.
- Fuel: more evaporation means more latent heat released in clouds, which drives the storm.
- Rapid intensification: Ockhi (2017) and Tauktae (2021) strengthened within hours, cutting warning time.
- Heavier rain: air holds about 7% more moisture per degree of warming.
- Arabian Sea shift: once quieter, it now sees more severe cyclones, such as Biparjoy (2023).
Wind shear and other factors still matter, so cyclone numbers may not rise, but stronger storms become more likely. Warning systems and coastal preparedness must adapt.
Keywords, cases and data to drop in
26.5°C threshold latent heat rapid intensification Arabian Sea warming Biparjoy
Where most answers lose marks
- Not explaining the mechanism.
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5 Oct 2026Learn the concept
Question text as printed in the official UPSC question paper: https://www.upsc.gov.in/sites/default/files/QP_CSM_2024_GenStud_I_03102024.pdf The model answer is original Battle IAS work; use it to learn structure, not to memorise.