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West Bengal is one of the most climatically vulnerable states of India — with a history of a high number of severe cyclones in the Bay of Bengal coast, severe thunderstorms, a high sea-level rise and projected flood risk. These observations were pointed out in India’s first official climate assessment report.
The Bay of Bengal region was struck by the highest number of cyclones in May and November according to the long-term analysis between 1891 and 2018, revealed the report Assessment of Climate Change over the Indian Region. It was released by the Ministry of Earth Sciences recently.
The region was hit by 41 severe cyclonic storms and 21 cyclonic storms in May during the given period. The figures jumped to 72 and 55 in November during the 127-year timeline. During the period, the Arabian Sea coast was struck by fewer cyclones.
The report found that from 2000 to 2018, the Bay of Bengal region experienced 16 Category 4 and above level cyclones — very severe cyclonic storms and extremely severe cyclonic storms — out of 22 cyclones that struck the region.
The report also mentioned a significant eastward shift in tropical cyclone genesis locations in the Bay of Bengal region during post-monsoon seasons, which may enhance the risk for the coastal regions of West Bengal.
During 2019-20, West Bengal coast witnessed landfalls of two extremely severe cyclones — Cyclone Bulbul and Cyclone Amphan — in November, 2019 and May, 2020.
While cyclone Bulbul had a maximum wind speed of 155 kilometre per hour, Amphan had maximum wind speed of 185 km per hour. Both made landfalls near the western part of Indian Sundarbans close to Sagar Island.
“According to our study, maximum landfalls happened in Sundarbans area within the Bay of Bengal coast line ranging from Orissa to Bangladesh,” said Sunondo Bandopadhyay, geography professor in Calcutta University.
The report mentioned that the flood risk increased over the east coast of India, with West Bengal being one the vulnerable states. “The flood risk has increased over the east coast; West Bengal, eastern Uttar Pradesh, Gujarat and Konkan region, as well as a majority of urban areas such as Mumbai, Kolkata and Chennai,” the report stated.
It added that as against the global average warming of 0.7 degrees Celsius, sea surface temperature of the tropical Indian Ocean rose by on an average of 1°C between 1951 and 2015. Such an increase in ocean temperature has a direct bearing on the intensity of thunderstorms and cyclones in the zone, experts noted.
“West Bengal experienced the most intense thunderstorm events and high casualties during the period (1978 -2012),” stated the report, hinting at the temperature rise linkage.
“West Bengal and surrounding regions recorded between 80 and 100 days of thunderstorm activity annually. The report findings hold significance for the state because rapid warming of the Indian Ocean is resulting in intense and extreme cyclones pummeling the entire coastal region of India,” said Aarti Khosla of Climate Trends, a climate assessment portal.
“Climatic impacts are responsible as sea surface temperature rise has contributed to the trend,” said an expert associated with the state environment department.
The report also pointed out that the sea level has been rising at a rate of five centimetres per decade off the Bengal coast — the highest in the country. The rise — considered a long-term impact of climate change — is about three centimetres per decade close to Mumbai.
The union government, in response to a question by the Trinamool Congress parliamentarian Saugoto Roy, had informed the Lok Sabha that the sea level rise was the highest at Diamonharbour near the mouth of the Sundarbans.
“The latest report has only established what independent experts have been saying for long — West Bengal needs a lot of support from the Centre and international sources to combat disasters triggered by increasing extreme weather events prodded by climate change,” said Javed Ahmed Khan, disaster management minister, West Bengal.