Bracing for Biparjoy: Cyclones hitting India's coasts become more frequent

Eastern seaboard most affected but the west is becoming more vulnerable too

Authorities in Gujarat have evacuated more than 75,000 people from coastal communities as cyclone Biparjoy whirls in from the Arabian Sea and makes landfall by Thursday evening. Cyclones have become more frequent in India since the seventies.

There have been six already between 2021 and 2022, according to the international Emergency Events Database (EM-DAT). That means an average of around three cyclones a year. The annual average was less than two in the previous decades (chart 1).

 

“Cyclones are becoming more frequent, intense and difficult to predict. North Indian Ocean is the fertile ground for deadly cyclones. In 2018, a total of 13 depressions were formed over the Bay of Bengal and the Arabian Sea which is the highest number in the last 28 years,” said a 2019 report by the National Disaster Management Authority on the Gaja cyclone that struck Tamil Nadu the year before.

Biparjoy, a ‘very severe cyclonic storm’, may cause extensive damage along the coastal areas of Gujarat, according to the India Meteorological Department. It is reportedly the cyclone with the longest life-span in the Arabian Sea.

Data shows that India’s east coast is the most affected by cyclones increasing over the past decades. Since the seventies, 14 cyclones have hit the east coast every decade on average, compared to two along the west coast (chart 2).

The broader trend suggests cyclones could become more frequent on India’s western coast. “Studies show a decreasing trend in the frequency of formation of Cyclonic Storms over the Bay of Bengal and an increasing trend over the Arabian Sea, based on the data during 1965-2020...However, the coastal vulnerability to the categories of Extremely Severe Cyclones’ or more continues over the Bay of Bengal region, as there is no significant trend in the frequency of Extremely Severe Cyclonic Storms (ESCS),” said a government statement in 2021 following a study.

High surface temperatures and the wind patterns in the Bay of Bengal make the east coast highly vulnerable to cyclonic storms. Mocha, one of the strongest cyclones to hit Myanmar, is said to have destroyed 90 per cent of the port city of Sittwe last month.

Since 1900 more than 2,400 cyclones have been reported in the world: 347 hit Philippines, the most affected. As many as 169 were reported to have hit China and 148 Japan. There have been 136 cyclones in the United States. India is fifth with 116 instances (chart 3).