Experts blame global warming for the intensity with which the cyclone made landfall on Wednesday
Cyclone Yaas, which made landfall over the north Odisha Coast on Wednesday morning, has now weakened into a deep depression as it moes over souther Jharkhand. The ‘very severe’ cyclone, which left four people dead and caused massive damage to property and farmlands in Odisha and West Bengal, recorded heavy rains and sustained wind speeds between 130-140 kmph gusting to 155 kmph while crossing the coast. Widespread rainfall has been forecast for the states of Odisha, Jharkhand and Bihar in the next 48 hours.
According to experts, global warming is to blame for the intensity with which the cyclone made landfall.
The climate change link
Cyclone Yaas triggered exceptionally warm sea surface temperatures of 30-31°C. Like Cyclone Tauktae in the Arabian Sea, which hit the country’s west coast last week, Yaas hit the Odisha coast with severe intensity, gathering its strength from the warmth and moisture in the Bay of Bengal. “The similarity between Cyclone Yaas and Cyclone Tauktae is that both are preceded by very high sea surface temperatures reaching 31-32°C. These high temperatures were conducive for Cyclone Tauktae to intensify into an extremely severe cyclone in a short time. Similarly, high temperatures are predicted to assist Yaas also for intensifying rapidly,” said Dr Roxy Mathew Koll, scientist, Indian Institute of Tropical Meteorology and lead author, IPCC Oceans and Cryosphere.
According to experts, this cyclogenesis can be attributed to climate change. Cyclones form when sea surface temperatures cross the threshold of 28°C. Indian seas have recorded higher than normal temperatures recently, thereby creating conditions which are conducive to frequent and rapidly intensifying cyclones. “Rapid intensification is the key point to focus on, as it will have direct impact on rainfall, destruction in terms of floods and gusty winds and evacuation process,” said Mahesh Palawat, Vice President of meteorology and climate change at Skymet Weather Services Pvt Ltd.
Koll, however, pointed to one major difference between Tauktae and Yaas. “Tauktae spent several days in the Arabian Sea where it could draw the heat and moisture continuously, reaching peak intensity of more than 220 km/hr. In the case of Yaas, it has formed in the north Bay of Bengal, and the travel distance to landfall is shorter. As a result, it won’t get a long period over the ocean to blow up to the intensity of Tauktae.” Also, unlike the Arabian Sea, which is seeing increasing cyclonic activity, there won’t be a significant rise in the number of cyclones in the Bay of Bengal, according to Koll.
Rapid intensification linked to warming seas is the common thread between both cyclones.
According to a study published in the American Meteorological Society, intensification rates, which traditionally occurred once in a century, will occur every 5-10 years by 2100.
The increasing risk of storm surges
Cyclones such as Yaas could potentially lead to storm surges. This coupled with the rising sea levels as a result of climate change could spell disaster for settlements in low-lying coastal areas. An India Meteorological Department (IMD) alert warned that after Cyclone Yaas makes landfall, tidal waves about 2-3 metres above astronomical tide are likely to inundate low-lying coastal areas of Balasore, Bhadrak, Medinipur, South 24 Parganas, Kendrapara and Jagatsinghpur Districts.
A 2019 study published in the journal Nature predicted annual coastal flooding would affect 36 million people in India by 2050.