The Indian Ocean is among the most cyclone-prone basins globally, driven by warm sea surface temperatures (SSTs), monsoonal circulation, and atmospheric instability. In May 2024, Cyclone Remal became the first cyclonic storm of the season, impacting West Bengal and Bangladesh with significant socio-economic and environmental consequences. This event highlights the intensifying trend of cyclones due to climate change, necessitating better preparedness and resilience.
What is a Cyclone?
A cyclone is a rapidly rotating storm system with a low-pressure center, strong winds, and spiraling clouds. It forms over warm oceans under the Coriolis effect.
Types of Cyclones
- Tropical cyclones – Warm oceans (5°–30° latitude), fueled by latent heat
- Extratropical cyclones – Mid-latitudes, caused by temperature gradients
- Mesocyclones – Rotating updrafts within thunderstorms, potential to form tornadoes
Terminology by Region
- Atlantic: Hurricanes (e.g., Katrina, 2005)
- Pacific: Typhoons (e.g., Haiyan, 2013)
- Indian Ocean: Tropical Cyclones (e.g., Remal, 2024)
Formation of Cyclone Remal
Cyclone Remal developed in the Bay of Bengal due to high SSTs (>27°C), strong evaporation, and favorable atmospheric conditions.
- Step 1: Low-pressure zone formed due to warm SSTs, rising moist air, and Coriolis effect
- Step 2: Intensified by ITCZ support and latent heat release, forming a strong vortex
- Step 3: Made landfall on May 26, 2024, near Sagar Island (West Bengal) and Khepupara (Bangladesh), bringing heavy rainfall and storm surges, before weakening over land
Impact of Cyclone Remal
On India
- West Bengal: Coastal flooding from 5–8 feet surges, Sundarbans salinity intrusion, infrastructure damage in Kolkata, Howrah, South 24 Parganas, $1 billion+ losses
- Odisha: Moderate rainfall with minimal damage
On Bangladesh
- Khulna, Barisal, Satkhira: Embankment breaches, severe flooding, $500 million+ losses, electricity and communications disrupted
Why Cyclones are Intensifying
Climate Change & Rising SSTs
- Oceans warmed ~1°C in the past century
- Increased ocean heat content fuels stronger cyclones
ENSO & Indian Ocean Dipole
- Positive IOD supports stronger cyclones
- El Niño suppresses Atlantic cyclones but strengthens Indian Ocean ones
Monsoonal Influence & Jet Streams
- Shift in tracks due to wind pattern changes
- Longer monsoon season → more cyclogenesis
Disaster Management and Preparedness
India’s Response
- Early warnings by IMD using satellites and Doppler radars
- 2 lakh+ evacuated to shelters
- Relief supplies (food, water, medicine) through NDMA/NDRF
Bangladesh’s Response
- Cyclone Preparedness Programme (CPP) evacuated 800,000+
- Embankment reinforcement limited large-scale flooding
Historical Comparisons
- 2019 Fani: $8.1 billion losses, Odisha
- 2020 Amphan: $13 billion, Bengal & Bangladesh
- 2021 Yaas: Severe flooding in Bengal, Odisha
- 2024 Remal: Moderate but widespread impacts, lower losses due to preparedness
Rising Intensity of Cyclones – Science and Evidence
Drivers of Intensification
- SSTs above 26.5°C supply latent heat
- Low vertical wind shear ensures storm organization
- Higher atmospheric humidity enhances rainfall
- Rapid intensification before landfall more common (e.g., Amphan 2020)
Impacts of Warming Oceans
- More Category 4–5 cyclones globally
- Faster intensification, shorter warning times
- Storm surges amplified by sea level rise
- Cyclone tracks shifting poleward, impacting new regions
Regional Trends
- Arabian Sea: Rise in severe post-monsoon cyclones
- Bay of Bengal: Shorter return period between strong cyclones
- Indian Ocean overall: Longer cyclone seasons, more pre- and post-monsoon storms
Environmental, Social, and Economic Impacts
- Erosion and salinity intrusion in Sundarbans and coastal deltas
- Agricultural losses due to flooding and salinization
- Infrastructure destruction (roads, bridges, power lines)
- Displacement and livelihood loss for coastal populations
Policy Recommendations
- Expand Doppler radar coverage and AI-based cyclone prediction
- Strengthen coastal infrastructure with resilient housing and embankments
- Restore mangroves as natural storm barriers
- Regional cooperation through SAARC & WMO for data sharing
- Climate mitigation via emission reduction to slow ocean warming
Conclusion
Cyclone Remal underscores how Indian Ocean cyclones are becoming stronger, wetter, and more destructive due to warming seas. While timely warnings saved thousands of lives, long-term adaptation requires investment in coastal resilience, ecological restoration, and climate action. For UPSC, Remal exemplifies the climate–disaster nexus, highlighting India’s dual challenge of immediate disaster management and long-term sustainable adaptation.