With cyclone Mocha expected to intensify as a very severe cyclonic storm, a study has revealed how climate change is making cyclones more intense on both sides of the Indian coast.
According to a study, “Changing status of tropical cyclones over the north Indian Ocean”, the translation speed of cyclones (the speed at which cyclones move) has decreased in the Arabian Sea.
“This means that cyclones are now moving slowly. The increase in cyclonic activity in the Arabian Sea is tightly linked to the rising ocean temperatures and increased availability of moisture under global warming,” states Climate Trends, a research-based consulting and capacity-building initiative that focuses on the environment, climate change and sustainable development.
During the study period (1982–2019), a significant increasing trend in the intensity, frequency, and duration of cyclonic storms (CS) and very severe CS (VSCS) was observed over the Arabian Sea.
There has been a 52% increase in the frequency of CS during the recent epoch (2001–2019) in the Arabian Sea, while there is a decrease of 8 percent in the Bay of Bengal.
“Weather conditions in the ocean are very supportive for rapid intensification of the system. Though the Bay of Bengal might have seen a decline in cyclogenesis but the intensity of the cyclones has increased manifold. Models are unable to pick up this rapid intensification of cyclones because they do not include ocean conditions properly, and that is their limitation. Cyclones nowadays can retain their energy for quite a long number of days,” said Dr Roxy Mathew Koll, a climate scientist at the Indian Institute of Tropical Meteorology and Lead IPCC Author.
Dr. Koll cites the example of Cyclone Amphan, which continued to travel over land as a strong cyclone and resulted in massive devastation.
Bay of Bengal
“As long as oceans are warm and winds are favourable, cyclones will retain their intensity for a longer period,” Dr. Koll said. He added that the Bay of Bengal has been riding on the wave of global warming during the past few decades.
“Temperatures have been between 30-32 degrees Celsius in the Bay of Bengal. These high temperatures play a very important role in the intensification of cyclonic storms as they infuse more convection. This kind of rapid intensification has become frequent recently both in the Arabian Sea as well as in the Bay of Bengal,” he added.