SYLLABUS
GS-1: Important Geophysical Phenomena such as earthquakes, Tsunami, Volcanic activity, cyclones, etc.
GS-3: Disaster and disaster management.
Context: A recent study published in Science Advances found that Tropical cyclones (TC) moving across exceptionally warm ocean waters associated with marine heatwaves could rapidly intensify and become stronger, leading to more severe impacts upon landfall and increasing economic losses.
Key Findings of the Study
• Tropical cyclones experiencing rapid intensification during marine heatwaves result in 60% more billion-dollar disasters compared to those without heatwave influence, even after accounting for coastal exposure.
• Researchers analyzed 1,600 landfalling tropical cyclones since 1981, finding that those passing over marine heatwave conditions were more likely to intensify rapidly.
• Costlier storms showed consistently higher maximum wind speeds (up to 20% higher in marine heatwave cases), storm surges, and precipitation rates (up to 12% higher).
• Billion-dollar tropical cyclones occur 1.6 times more frequently when marine heatwaves are present.
About Marine Heatwaves and Linkage with Tropical Cyclones
• Marine heatwaves refer to prolonged periods of abnormally high ocean temperatures, lasting from days to months and extending over large oceanic regions.
• They are driven by climate change, ocean circulation anomalies, and climatic phenomena such as El Niño.
• Tropical cyclones derive their energy from warm ocean waters, and higher sea surface temperatures enhance the transfer of heat and moisture from the ocean to the atmosphere.
• When cyclones pass over marine heatwave regions, they encounter elevated ocean heat content, which acts as an additional energy source.
• Elevated sea surface temperatures lead to:
- Rapid intensification of cyclones within short durations
- Higher wind speeds and increased rainfall
- Prolonged duration and sustained intensity of storms
• This interaction represents a compound climate effect, where multiple hazards reinforce each other.
Implications
• Global:
- Intensified cyclones result in greater economic losses, affecting infrastructure, supply chains, and insurance systems worldwide.
- Marine ecosystems face stress due to coral bleaching, biodiversity loss, and disruptions in fisheries.
- Disaster management systems are challenged by rapid intensification, reducing response time for evacuation and preparedness.
- Vulnerable developing countries face disproportionate impacts, widening global inequality in climate resilience.
• India:
- The Arabian Sea and Bay of Bengal are experiencing rising sea surface temperatures, increasing the likelihood of stronger cyclones.
- India may face:
More intense cyclones such as those observed in recent years
Increased coastal flooding, erosion, and displacement
Threats to agriculture, fisheries, and coastal livelihoods
- The phenomenon also complicates monsoon dynamics and disaster management planning, requiring improved forecasting systems.
About Tropical Cyclones
• Tropical cyclones are intense low-pressure systems that form over warm ocean waters in tropical regions.
• They are characterised by:
- Strong winds exceeding 119 km/h
- Heavy rainfall and storm surges
• They form under specific conditions, including:
- Sea surface temperatures above 26–27°C
- High humidity and low vertical wind shear
• These systems are known by different names across regions, such as cyclones in the Indian Ocean, hurricanes in the Atlantic, and typhoons in the Pacific.
• Climate change is influencing cyclone behaviour, leading to greater intensity, rapid intensification, and changing spatial distribution.
• On the basis of wind speed and the degree of potential destruction, Cyclones can be categorized as:
- Low Pressure: Wind speeds below 31 km/h
- Depression: Wind speeds between 32–61 km/h
- Cyclonic Storm: Wind speeds between 62–88 km/h
- Severe Cyclonic Storm: Wind speeds between 89–117 km/h
- Very Severe Cyclonic Storm: Wind speeds between 118–167 km/h
- Extremely Severe Cyclonic Storm: Wind speeds between 168–221 km/h
- Super Cyclone: Wind speeds exceeding 221 km/h
• Naming of Cyclones:
- Worldwide, there are six regional specialised meteorological centres (RSMCs) and five regional Tropical Cyclone Warning Centres (TCWCs) mandated for issuing advisories and naming of tropical cyclones.
- India Meteorological Department (IMD) is one of the six RSMCs to provide tropical cyclone and storm surge advisories to 13 member countries under the WMO/ESCAP Panel on Tropical Cyclones.
13 member countries: Bangladesh, India, Iran, Maldives, Myanmar, Oman, Pakistan, Qatar, Saudi Arabia, Sri Lanka, Thailand, United Arab Emirates and Yemen
- In April 2020, the IMD released a list of 169 cyclone names, with each of the 13 member countries contributing 13 names.
- The cyclone name list arranges member countries alphabetically, with each country’s suggested names listed alongside.
- Then these names are allotted to any cyclone which takes place in the region, on a rotational basis, regardless of which country proposed it.