Ocean surface temperature, heat wave incidents up in Indian Ocean

New Delhi, March 24 If you thought heat waves are something to do with increased temperatures on the land in summer months, it is time for a rethink!

Not only are there heat waves in the ocean, which is heating too, but they are increasing too over the decades.

The western Indian Ocean had a total of 66 Marine Heat Wave (MHW) events while the Bay of Bengal had 94 events during 1982-2018, a recent investigation of marine heat waves by the scientists at the Indian Institute of Tropical Meteorology (IITM), an autonomous institute under the Ministry of Earth Sciences, found out.

"The western Indian Ocean region experienced a four-fold rise in marine heat wave events (increasing at a rate of 1.5 events per decade) and the north Bay of Bengal experienced a two-to-three fold rise (at a rate of 0.5 events per decade)," the Parliament was informed on Thursday.

In recent decades, the tropical Indian Ocean has experienced a rapid increase in ocean warming with an average rise in sea surface temperature (SST) of about 1 degree Celsius over the period of 1951-2015 at a rate of 0.15 degrees Celsius/decade.

In 2021, there were six marine heat waves recorded in the western Indian Ocean over a period of 52 days. In the north Bay of Bengal, there were four marine heat waves over a period of 32 days.

"These heat waves did not break all previous records but were above normal. The western Indian Ocean heat waves in 2021 were in the top four years in terms of the number of events," Minister for Earth Sciences, Jitendra Singh, told the Rajya Sabha.

The monsoon forecast models used by the India Meteorological Department (IMD) considers the ocean surface temperatures as input data. These forecasts can be used for advance planning and disaster management.