The phenomenon is the result of global warming which has led to increase in the rate of temperature rise over Arabian Sea, researchers say.
This rise is reducing temperature difference between land and sea, known as Temperature Gradient (TG), responsible for attracting rain causing winds from Arabian Sea towards Indian mainland.
"For climatology, 30 years variations are considered. The decreasing trend (of TG) is highly significant and in another 150 years or so, it may tend to zero," lead author S M Bawiskar, a scientist at the Pune-based institute, said.
Once the gradient becomes zero, Bawiskar warns, the monsoon winds will be replaced by dry easterly winds thus disturbing the flow of south-west monsoon.
He found that average temperature over Arabian Sea was 18.77 degrees Celsius during 1948-77 but it has increased by 0.87 degrees to touch 19.64 degrees during 1979-2008.
The results published in the Journal of Earth System Science show that rate of temperature increase over sea is higher than land which has narrowed the Gradient by 1.11 degrees during the said period.
