An assessment of climate change over the Indian region has said that an eastward shift in the post-monsoon tropical cyclone formation in the Bay of Bengal has made Bangladesh more vulnerable to very severe cyclonic storms.
India’s Ministry of Earth Sciences relied on long-period records, some dating back to 1874, to assess climate change in the Indian region for the first time and officially published its findings in a report on Friday.
Very severe cyclonic storms have become more frequent in the post-monsoon season, which expands from October to December, in the North Indian Ocean over the past two decades starting in 2000, said the report.
‘A significant eastward shift in tropical cyclone genesis locations in the Bay of Bengal tends to enhance the vulnerability for the coastal regions of Bangladesh,’ noted the report.
Analysing data from 1891 to 2018, the report revealed a 49 per cent rise in severe cyclonic storms in the Bay of Bengal regions after 1950.
Of the very severe cyclonic storms formed during the time, 60 per cent made landfall in India’s east coast while 30 per cent re-curved to head for Bangladesh, said the report.
The majority of the tropical cyclones formed in the Bay of Bengal turned very severe or extremely severe, it said.
According to the report, the high-sea surface temperature supplies energy for cyclonic storms and the Indian Ocean warmed up by 1degree Celcius between 1951 and 2015.
Contrarily, the global average warming of sea surface temperature for the period was 0.7 C.
One finding of the report said that the rapid warming of the Indian Ocean is resulting in intense and extreme cyclones pummelling the entire South Asia region, especially countries in the North Indian Ocean rim, including Bangladesh.
In less than 15 days between May 20 and June 3, two powerful cyclones made landfall between the India east coast and Bangladesh.
The report predicted that tropical cyclone intensity would increase throughout the 21st century.
The North Indian Ocean basin accounts for up to 10 per cent of the world’s tropical cyclones, considered the most deadly ones in the world, said the report.
Because of the thermal expansion of water and the continental ice melting, the report said, the level at North Indian Ocean rose up to 1.75 mm per year over the 1874–2004 period.
The sea-level rise sharply accelerated over the last two and half decades with a 3.3 mm per year rise between 1993 and 2017, it said.
The seal level at Hiron Point on the western coast of Bangladesh rose by 4.46 mm every year from April, 1990 to March 2009, which was greater than the global rate of 3.3 mm annual rise over the period between1993 and 2007, according to the report.
Besides the changes in sea level and cyclone intensity, the report also revealed decrease in monsoon precipitation and rise in extreme rainfall events and droughts.
‘There is compelling scientific evidence that human activities have influenced these changes in the regional climate,’ the report concluded.
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