Impact of climate change on Southwest Monsoon is showing: Experts

Vibha Sharma
Tribune News Service
New Delhi, June 4   

On eve of World Environment Day,  experts say the impact of climate change has started showing on the Southwest Monsoon on which two-third of India’s agricultural tracts depend. Back-to-back powerful cyclones Tauktae and Yaas on either side of the Indian coast not only delayed the onset of Monsoon 2021 in Kerala but also impacted its current. 

Monsoon arrived on the Indian mainland on June 3 against the normal onset date of June 1. Earlier the IMD had predicted its arrival on May 31, which it later changed. 

Experts say the formation of Yaas in the Bay of Bengal coincided with the time of onset, which “held the Monsoon wave”. 

GP Sharma, chief of meteorology and climate change at Skymet Weather, says Tauktae and Yaas took away “much of the kinetic energy from the water bodies, which almost ceased the weather activity in Kerala. Required wind patterns and speed were also absent.  Tauktae and Yaas put a brake on the momentum”.

Sushant Puranik from the Department of Atmospheric and Space Science at the University of Pune also says that Yaas intensified rapidly due to conducive atmospheric conditions, taking away all the moisture and energy.

“Winds too started concentrating over the system. As a result, the eastern arm of the Monsoon that passes through the Bay of Bengal became more powerful, while the western arm that moves through the Arabian Sea became weak. 

"For the onset of Monsoon, the western arm must be stronger and take the lead. As a result, there was a delay in Monsoon's arrival over Kerala".

Though weathermen also say that upcoming cyclonic circulations will strengthen the current.

Matthew Roxy Koll, a climate scientist at the Indian Institute of Tropical Meteorology, says that the global ocean has absorbed 90 per cent of the excess heat generated by greenhouse gas (GHG) emissions since 1970.

“This has led to anomalous ocean warming in Arabian Sea and Bay of Bengal, which in turn makes cyclones intensify rapidly. Heat is energy, and cyclones intensify rapidly by turning the potential energy stored in the ocean into kinetic energy.

“The western tropical Indian Ocean has been warming for more than a century, at a rate faster than any other region of the tropical oceans and turns out to be the largest contributor to the overall trend in the global mean SSTs”.

Studies indicate that frequency of extremely severe cyclonic storms over the Arabian Sea has increased during the post-monsoon seasons of 1998–2018 also according to a report by the Ministry of Earth Sciences (MoES), climate models project a rise in the intensity of tropical cyclones in the North India Ocean basin during the twenty-first century. Climate change' signal to changes in SST and associated Tropical Cyclone activity might emerge sooner in the Indian Ocean as compared to other ocean basins, experts say.