National Institute of Oceanography launches study on changing monsoon trends

KOCHI: With climate change triggering extreme weather events and changing the monsoon pattern, the Goa-headquartered National Institute of Oceanography (NIO) has launched a study into the factors that caused the change and their impact.

“We have launched a study into the cyclonic events that occurred in the Bay of Bengal and Arabian Sea from 1960 to 2019,” said NIO Emeritus Scientist S Prasannakumar.

“Though the Bay of Bengal had been witnessing frequent cyclonic storms, the Arabian sea was relatively calm. However, the latter started witnessing category II cyclones, after 2000. The number and intensity of cyclones in the region has been rising over a period of time. There were five cyclones in the Arabian Sea in 2019,” he said. The study is expected to be published within eight months.

According to him, the surface water in Arabian Sea has been warming up which could have impacted the monsoon pattern. “Kerala used to receive around 70 per cent of the Southwest Monsoon rainfall during June-July (period). However, this has shifted to August-September of late. The withdrawal of Southwest Monsoon was also delayed this time, which adversely affected the onset of Northeast Monsoon. These changes need to be examined closely,” said Prasannakumar.

The NIO will study the changes in the surface water of Arabian sea, up to a depth of 100m, which could have affected the monsoon pattern and created conditions favourable for cyclonic storms.

“The Arabian sea witnesses a process called upwelling during the monsoon season that brings plankton from the depth of the sea to the surface. This attracts sardines and mackerel to the coastal sea supporting the livelihood of fishermen. The change in temperature of surface water and upwelling process might have led to the depletion of fish stocks,” he said.

Effects on fisherfolk

A section of the fishermen have stopped venturing into the sea as there is a steep decrease in the availability of fish in the coastal sea.

“The country boats that venture into the sea are not able to get sufficient catch to meet the fuel cost. More than 50 per cent of the country boats have stopped venturing into the sea after the withdrawal of Southwest Monsoon.

The traditional fishermen are forced to search for other jobs to support themselves,” said National Fishworkers’ Forum general secretary T Peter.

Echoing the concerns raised by traditional fishermen, mechanised boat operators also said they are incurring huge loss due to depleting fish stocks.

“The fish stocks have migrated from Kerala coast and we are not able to get sufficient catch even from the deep sea. Earlier we used to get schools of a particular species of fish, but now the catch is mixed. Many boat operators have stopped venturing into the sea as they are not able to meet the operating cost,” said All Kerala Fishing Boat Operators’ Association general secretary Joseph Xavier Kalappurakkal.

However, scientists said the situation was not alarming as it is a lean season. “The fish stocks may migrate to the deep sea or cooler regions as the surface water gets warm. Though the climate is cool in North India winter is yet to arrive in Kerala. Besides the surface water is warm as daytime temperature has gone up,” said Central Marine Fisheries Research Institute (CMFRI) principal scientist K Sunil Mohamed.

New normal?

Kerala used to receive around 70% of Southwest Monsoon rain in June-July. This has shifted to August-September

The delay in withdrawal has also affected the onset of Northeast Monsoon