Que: What is sea surface temperature rise? How does it affect the formation of tropical cyclones? 

Sea surface temperature rise is the increase in the temperature of ocean surface water, which is a key indicator of global climate change. This increase usually occurs at a rate of more than 0.5°C and is known as sea surface temperature rise (SST). It absorbs more than 90% of the global temperature increase into the ocean, causing the ocean temperature to rise. The year 2023 saw a record increase in sea surface temperature due to El Niño and greenhouse gases.

• Main causes:

• Human activities and greenhouse gases: Emissions of carbon dioxide and other gases increase the temperature in the atmosphere, which is absorbed by the ocean.

• Climate events such as El Niño: This changes the distribution of warm water in the Pacific Ocean, which increases the temperature.

• Solar radiation and atmospheric factors: Solar radiation and cloud cover also affect the temperature, but the main cause is climate change. This increase is observed at a global level, such as in the Bay of Bengal and the Arabian Sea, where the temperature reaches 28-29°C.

• How does it affect the formation of tropical cyclones?

• Tropical cyclones are formed by gaining energy from warm ocean waters, and an increase in sea surface temperature increases their formation, intensity and frequency. A minimum temperature of 26.5-27°C is required for the formation of cyclones, as it increases evaporation and releases latent heat, which gives strength to the cyclone. An increase in sea surface temperature accelerates this process.

• Increased formation and intensity: Higher temperatures cause more evaporation, which forms clouds and releases latent heat, making the cyclone more intense. For example, 28-29°C SST is favorable for the formation and development of cyclones. Climate change is leading to more intense cyclones, such as Cyclone Taukte in the Arabian Sea.

• Increased frequency and duration: Higher temperatures are leading to cyclones forming over a wider area, such as in areas far from the equator, increasing their duration and intensity, which brings more rainfall and flooding.

• Implications in the Indian context: In India, rising sea surface temperatures in the Bay of Bengal and the Arabian Sea are leading to more cyclones, affecting the east and west coasts. India experiences 10% of the world’s cyclones and higher temperatures bring more destructive storms. This leads to greater intensity, which makes forecasting difficult.

• Connection with other factors: Rising sea surface temperatures work together with the Coriolis force, low vertical wind shear and pre-existing low pressure.

To mitigate these effects, organisations like the India Meteorological Department monitor rising sea surface temperatures and issue advance warnings.