Warming of Arabian Sea raising cyclone frequency

Back in November 1940, when cyclones didn't have names, the Arabian Sea threw an unprecedented, untimely night-long tantrum that cost the city more than Rs 25 lakh. In the aftermath, bodies floated at Apollo Bunder, Colaba, Mazgaon docks and other sea faces even as piles of planks, broken masts and other pieces of timber turned the harbour from Colaba to Sewri into one long graveyard of ships.


The next one in 1948, again in November, left wreckage in its wake from cargoes carried by around 300 "country craft", littering fishing villages in Versova, Danda and Thana too. About 100 lives, chiefly crew and owners of ships and boats, were feared lost and a 1,000-ton Norwegian steamer called 'Marly'--which left Bombay for the Malabar coast--vanished. According to TOI reports, seven people were killed in the city on the day and a hundred injured.

'Tauktae' is probably the closest Mumbai has come since to experiencing a severe storm, with wind speeds of up to 108 kmph near the Colaba seafront. Tauktae, experts say, was at its most intense at its closest to the Mumbai coast (distance of 120 km) before it propelled away towards Gujarat. An extreme weather event of this nature, so close to the city, portends a warning about the likely consequences of ignoring climate change, say experts.

This is the third year in a row that cyclones in the Arabian Sea have menaced the west coast. Nisarga in 2020 even made landfall near Alibaug in Maharashtra while in 2019 Vayu moved parallel to the shoreline.

Experts said the recent frequency of cyclones was a clear sign of temperatures rising in the Arabian Sea. These low-pressure systems are formed when warm, moist air rises up from the sea surface. Historically, waters off the western coast have experienced fewer storms than the Bay of Bengal, and typically weaker. "The rapid warming of the Arabian Sea is leading to not just more cyclones but also more extreme rain events... Due to these warm ocean conditions it is seen that the cyclone intensifies from a weak cyclone to an extremely severe cyclone rapidly. This rapid intensification also means we need to ensure our forecasting is accurate," said Roxy Mathew Koll, a climate scientist at the Indian Institute of Tropical Meteorology (IITM), Pune.

Akshay Deoras, an independent meteorologist and a PhD student at the department of meteorology, University of Reading in UK, said a cyclone is not much of a menace if it dissipates over the sea itself. “However, if it comes so close to the coast like cyclone Tauktae did and Nisarga last year which made a landfall here, then it’s a massive threat. Also with it intensifying so rapidly, the authorities find very little time to evacuate those living along the coast. This is now seen to be happening frequently with the storms in the Arabian Sea," said Deoras.

With little control over the discharge of greenhouse gases and the consequent rise in temperatures, warming in the Arabian Sea is certainly a trend that’s likely to written about in these columns again and again.