What is sea surface temperature rise? How does it affect the formation of tropical cyclones?
Approach · directive: “what / how”
What it asks · Define the warming of the ocean's upper layer and explain the physical link between warmer seas and the genesis, intensity and frequency of tropical cyclones.
It asks 2 things — answer each
- Define sea surface temperature rise and what drives it
- Explain how SST rise affects the formation of tropical cyclones: energy supply, intensity, location and the other conditions still required
Open with · NCERT calls a tropical cyclone a heat engine energised by latent heat released when moisture gathered over the sea condenses; a sea surface above 27°C is its first condition.
Cover
- Meaning: SST is the temperature of the ocean's top layer; its rise is sustained warming of that layer.
- Drivers: greenhouse warming, marine heatwaves and warm phases of ENSO and the Indian Ocean Dipole.
- Visual: flowchart from warmer sea to evaporation, latent heat, deeper low and stronger cyclone.
- More fuel and wider window: the 27°C threshold is met over larger areas and longer seasons.
- Intensity: rapid intensification (Ockhi 2017, Tauktae 2021); IPCC AR6: share of Category 3–5 cyclones likely up over four decades.
- Location: MoES (2021) reports a rising trend over the Arabian Sea, falling over the Bay of Bengal.
- Necessary, not sufficient: Coriolis force, low vertical wind shear and a pre-existing low still required.
- Way forward: NCRMP shelters and early warning in 8 coastal States; mangroves, coastal zoning, ocean-heat forecasting.
Close with · As seas warm, cyclone losses will hinge on how fast coastal India adapts; warnings, shelters and mangroves cost less than recovery.
Add value (verified)
- Ministry of Earth Sciences told Parliament (2021) that cyclonic storm formation shows a decreasing trend over the Bay of Bengal but an increasing trend over the Arabian Sea.Study on Cyclones — PIB, Ministry of Earth Sciences, 15 March 2021 ↗“Studies show a decreasing trend in the frequency of formation of Cyclonic Storms over the Bay of Bengal and an increasing trend over the Arabian Sea”
- IPCC AR6 (2021): the global proportion of major (Category 3–5) tropical cyclones has likely increased over the last four decades.Climate Change 2021: The Physical Science Basis, Summary for Policymakers — IPCC AR6 WG I ↗“It is likely that the global proportion of major (Category 3–5) tropical cyclone occurrence has increased over the last four decades”
- PIB (4 Feb 2025): the National Cyclone Risk Mitigation Project was implemented in 8 coastal States in two phases, with multi-purpose cyclone shelters and early warning dissemination systems.National Cyclone Risk Mitigation Project (NCRMP) — PIB, Ministry of Home Affairs (4 Feb 2025) ↗“NCRMP was implemented in the 8 coastal States, in two phases.”
Question: UPSC's CS (Main) 2024, GS Paper I — paper ↗. Approach: Minimalist IAS, checked 16 Oct 2026 (how we verify) — UPSC publishes no model answers. ·
Model answer· 221words · Minimalist IAS
NCERT calls a tropical cyclone a heat engine run on latent heat from condensing sea moisture; a sea surface above 27°C is its first condition. Warmer seas therefore feed it directly.
Meaning of SST rise
- Meaning: sea surface temperature (SST) is the temperature of the ocean's top layer; its rise is sustained warming of that layer.
- Drivers: greenhouse warming, marine heatwaves and warm ENSO and Indian Ocean Dipole phases.
How it affects cyclone formation
- Warmer sea
- more evaporation
- latent heat
- deeper low
- stronger cyclone
- Wider window: the 27°C threshold is met over larger areas and longer seasons.
- Rapid intensification: deep warm layers resist storm-induced cooling; Ockhi (2017) and Tauktae (2021) intensified rapidly.
- Stronger storms: IPCC AR6: the global share of Category 3–5 cyclones has likely risen over four decades.
- Shifting basins: MoES (2021) reports a rising trend over the Arabian Sea, a falling one over the Bay of Bengal.
- Necessary, not sufficient: Coriolis force, low vertical wind shear and a pre-existing low are still needed; hence no cyclones at the equator.
Way forward
- Shelters and warnings: the National Cyclone Risk Mitigation Project gave 8 coastal States multi-purpose shelters and early warning systems.
- Buffers: mangrove belts, coastal zoning and ocean-heat forecasting.
As seas warm, cyclone losses will hinge on how fast coastal India adapts; warnings, shelters and mangroves cost less than recovery.
Prepared by Minimalist IAS to the answer standard of Shivam Singh (mentor, 7 years) · facts checked against official sources (how we verify) · updated 16 Oct 2026. UPSC publishes no model answers: compare your structure and coverage with this, then write your own.
