An important new report is due from the UN’s Intergovernmental Panel on Climate Change (IPCC) tomorrow. The report will be focusing on the latest scientific evidence on the impacts of a rapidly warming climate, as well as ways in which countries and communities can seek to adapt to these impacts. As we have seen over the past few years, some of the most extreme impacts of the climate crisis have been playing out in India. In fact, in some ways, India is in a unique situation where it’s facing a variety of impacts, from disappearing Himalayan glaciers to heatwaves to erratic monsoon rainfall and rising sea levels.
One of the gravest threats posed to India’s coastal regions is from super-storms arising from the sea. Over the past few years, we have seen at least two major, destructive cyclones making landfall each year. In 2020 and 2021, cyclones Amphan, Tauktae, Yaas, Nisarga and Nivar—all arising in either the Bay of Bengal or the Arabian Sea—made landfall, causing immense destruction. Although the most extreme of the lot was Amphan, a Category 5 supercyclone, the others were just as intense, and proof that the overheated waters of the northern Indian Ocean have become a breeding ground for cyclones.
A new review paper by Indian scientists, published earlier this week, looks into the reasons why this is happening and the role that climate change is playing. The paper, A Review Of Ocean-Atmosphere Interactions During Tropical Cyclones In The North Indian Ocean, published in the journal Earth Science Reviews provides a timely insight into how cyclones are becoming more frequent and more intense. The paper is written by scientists Vineet Kumar Singh and Roxy Mathew Koll, both from the Indian Institute of Tropical Meteorology-Pune (IITM), and builds on a major study the two co-wrote with other Indian scientists last year.
The latest paper analyses a variety of data, including the one that’s most important to the creation of cyclones: hotter than normal sea surface temperatures (SST). Over the past 50 years, the global ocean has absorbed 90% of the excess heat generated due to man-made climate change. This has resulted in massive ocean warming, unleashing stronger storms. And nowhere is this impact seen more clearly than in the north Indian Ocean, comprising the Arabian Sea and the Bay of Bengal. In the Arabian Sea, SSTs have been 1.2-1.4 degree Celsius higher than normal, and in the past 20 years, there has been a 52% increase in the number of cyclones in the Arabian Sea. In the same period, the number of very severe cyclonic storms (VSCS), with wind speeds of 118-165 km per hour, has increased by a ridiculous 150% in the Arabian Sea.
8/ #ClimateChange— Roxy Koll ⛈ (@rocksea) February 24, 2022
Sea surface temperatures leading to cyclogenesis in the Arabian Sea are 1.2–1.4°C higher in recent decades compared to four decades ago. Rapid warming tends to enhance the heat flux from the ocean to the atmosphere and favor rapid intensification of cyclones. pic.twitter.com/X8VEAMz3ZH
The new paper investigates how high SSTs and other oceanic conditions in the north Indian Ocean aid the creation of powerful and destructive cyclones. This is of immense importance, because, as scientific studies have shown, due to climate change, extreme weather events will keep becoming more frequent and also more intense. It is in our best interests to understand how and why this is happening and then acting on it. As Koll said to me last year, “Floods and storm surges from cyclones or heavy rains are going to increase. And we need urgent action. First we need to do risk assessment mapping on the basis of these new trends. And on the basis of that we need to take appropriate action.”