Q4. What is sea surface temperature rise? How does it affect the formation of tropical cyclones? (10M)

Introduction

Sea Surface Temperature (SST) rise refers to the increase in the temperature of the ocean’s surface waters, typically driven by global warming and climate change. SST is crucial in determining weather patterns and influencing oceanic and atmospheric processes. One of the most critical consequences of rising SST is its effect on the formation and intensity of tropical cyclones (also known as hurricanes, typhoons, or cyclones depending on the region).

Causes of SST Rise:

• Greenhouse Gas Emissions: The primary driver of SST rise is the increased concentration of greenhouse gases (GHGs) like carbon dioxide (CO₂) and methane (CH₄), which trap heat in the Earth’s atmosphere and oceans.

• E.g. According to IPCC, emissions of greenhouse gases from human activities are responsible for approximately 1.1°C of warming since 1850-1900.

• El Niño Phenomenon: This periodic climate pattern causes the warming of central and eastern Pacific Ocean waters, contributing to global SST variations.

• Changes in Ocean Circulation: Disruptions in ocean currents can redistribute heat, leading to localized SST increases in certain regions.

Impact of SST Rise on Tropical Cyclone Formation:

• Fuel for Cyclones: Tropical cyclones derive their energy from warm ocean waters. SSTs above 26.5°C are generally required for cyclone formation. The warmer the ocean surface, the more energy is available for the storm to intensify. g. Rising SST increases the evaporation rate of surface water, leading to more moisture in the atmosphere.

• g. Rising SST increases the evaporation rate of surface water, leading to more moisture in the atmosphere.

• Enhanced Latent Heat Release: Warm sea surfaces lead to greater evaporation and condensation of water vapour in the atmosphere. When water vapour condenses into rain within a cyclone, it releases latent heat, which further warms the air and lowers the pressure at the cyclone’s centre. This heat release accelerates the updrafts in the storm, promoting the formation of a more organized and powerful tropical cyclone.

• This heat release accelerates the updrafts in the storm, promoting the formation of a more organized and powerful tropical cyclone.

• Increased Storm Intensity: As SSTs rise, the intensity of tropical cyclones is likely to increase. According to climate models, the frequency of Category 4 and 5 storms (the most destructive) has been rising in recent decades g. the 2020 Atlantic hurricane season recorded a record number of storms, many of which were intensified by warmer SSTs.

• g. the 2020 Atlantic hurricane season recorded a record number of storms, many of which were intensified by warmer SSTs.

• Changes in Cyclone Track and Frequency: SST rise can influence the geographic distribution of tropical cyclones. Warmer waters further north or south from the equator may lead to cyclones forming and moving into regions where they were previously uncommon. g. As per Science Direct, tropical cyclone tracks are shifting towards higher latitudes, in part due to warming SST.

• g. As per Science Direct, tropical cyclone tracks are shifting towards higher latitudes, in part due to warming SST.

• Rising Sea Levels: Rising sea levels, another consequence of SST rise and global warming, exacerbate the impacts of tropical cyclones. Higher sea levels increase the risk of storm surges, where ocean waters are pushed inland, causing severe flooding during a cyclone. g. Storm surge flooding can be catastrophic in low-lying coastal areas, particularly in regions like the Bay of Bengal and the eastern coast of India.

• g. Storm surge flooding can be catastrophic in low-lying coastal areas, particularly in regions like the Bay of Bengal and the eastern coast of India.

• Impact on Cyclone Durability: Warmer oceans provide more heat energy, allowing tropical cyclones to sustain their intensity for longer periods. g. Cyclone Amphan (2020), which hit India and Bangladesh, maintained its intensity due to unusually warm Bay of Bengal waters.

• g. Cyclone Amphan (2020), which hit India and Bangladesh, maintained its intensity due to unusually warm Bay of Bengal waters.

Conclusion

The Indian government introduced the National Action Plan on Climate Change (NAPCC), which features the National Adaptation Fund for Climate Change (NAFCC). Its objective is to bolster climate-resilient infrastructure and enhance disaster preparedness, focusing on mitigating the effects of increasing sea surface temperatures (SSTs) on tropical cyclones.