Stronger monsoon winds are bringing significantly more rainfall to typically semi-arid regions of north-west India, says a new research by the University of Southampton on climate change contradiction.

The study, led by Ligin Joseph, a postgraduate researcher in Ocean and Earth Science at the University, found a 40 per cent increase in summer (south-west) monsoon rainfall over north-west India in recent years compared to the 1980s. 

“This finding challenges the widely held belief that climate change intensifies existing precipitation patterns, making dry regions drier and wet regions wetter,” a statement from the university said.

Contradicting narrative

Joseph said, “The 40 per cent increase in summer monsoon rains came as a surprise to us. It contradicts the widely accepted narrative that global warming is leading to dry regions becoming drier and wet regions becoming wetter. Here, we have the opposite.”

The research team linked this unexpected phenomenon to stronger monsoon winds, driven by the rapid warming of the Indian Ocean and enhanced Pacific Ocean trade winds – both heavily influenced by climate change. 

The analysis suggests that a noticeable warming of the sea surface in the western equatorial Indian Ocean and the Arabian Sea could be causing this increase in rainfall. 

This warming strengthens the winds crossing the equator in the Indian Ocean and increases evaporation. The study also shows that the monsoon winds are strengthened due to the rapid warming of the Indian Ocean and the enhanced Pacific Ocean trade winds. 

These stronger winds cause more evaporation, which means more moisture is carried from the ocean to the land, leading to increased monsoon rainfall.

Implications

The Indian Meteorological Department recorded above-normal rainfall in northwest India, including Delhi, Gujarat, and Rajasthan, during the recently-concluded monsoon season.

The study’s findings have implications for rainfall predictions in India in the future. The Clausius-Clapeyron relation states that the water-holding capacity of the air increases by seven per cent per degree of global warming.

“Our findings suggest that future changes in India’s precipitation patterns will largely hinge on shifts in monsoon atmospheric circulation,” said Joseph.

This research highlights the contradictory ways climate change impacts regional weather patterns. Further investigation is crucial to improve rainfall predictions and inform adaptation strategies in vulnerable regions like northwest India.

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