Climate change is making cyclones more intense

Amid the build-up of cyclone Mocha over the Bay of Bengal, experts say that climate change is making cyclones more intense on both sides of the Indian coast.

Over the last few years, cyclones have made their impact visible on the Arabian Sea in the western coast and Bay of Bengal on the eastern coast.

Tropical cyclones are one of the most devastating natural disasters costing more than half a million lives all over the world in the last five decades. The Indian Ocean region, including the Arabian Sea and the Bay of Bengal is of particular concern because of the high population density along its coastlines.

May is the peak month for cyclogenesis in the Indian Ocean, hence the formation of a tropical cyclone is very timely. However, the rapid intensification of these storms is a matter of concern. Researchers and scientists have been blaming increasing global mean temperature behind the changes in the cyclogenesis, particularly over the Indian Ocean, according to a report by Climate Trends.

“The mechanism behind the formation of cyclones does not change but weather conditions are changing. Cyclones have been intensifying at a faster pace in the recent past. The reason for this is not just an increase in the sea-surface temperatures (SSTs) but rising ocean heat content (OHC) also. Earlier the system used to take 2-3 days before forming into a tropical storm but nowadays the change from depression into cyclonic storm takes just a day. Atmosphere not only interacts with SSTs but also with the entire ocean,” the report points out.

“Both Sea Surface Temperatures and Ocean Heat Content are projected to increase in the future. There will be a warmer and wetter world over oceans and more energy will be available for evaporation, facilitating more tropical cyclonic activity and more rainfall. There may be fewer but more intense storms, with relatively higher chances of Category 4 or 5 storms,” the report states.

“Cyclones nowadays can retain their energy for quite a long number of days. One example of this trend was Cyclone Amphan which continued to travel over land as a strong cyclone and resulted in massive devastation. As long as oceans are warm and winds are favourable,

cyclones will retain their intensity for a longer period,” said Dr Roxy Mathew Koll, Climate Scientist at the Indian Institute of Tropical Meteorology and Lead IPCC Author.

“Sea surface temperatures are increasing. The mechanism behind the formation of cyclones does not change but weather conditions are changing. Cyclones have been intensifying at a faster pace in the recent past,” said Dr M M Ali, Meteorologist and Oceanologist, Andhra Pradesh State Disaster Management Authority and Emeritus Scientist G andGroup Director – Atmosphere, ISRO, Indian Space Research Organisation.