New research from the University of Southampton reveals a climate change contradiction: stronger monsoon winds are bringing significantly more rainfall to typically semi-arid regions of northwest India. The study, led by Ligin Joseph, a postgraduate researcher in Ocean and Earth Science at the University of Southampton, found a 40 percent increase in summer monsoon rainfall over northwest 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.
Ligin Joseph, a postgraduate researcher in Ocean and Earth Science at the University of Southampton, said: "The 40 percent 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. These stronger winds increase evaporation over the Indian Ocean, leading to more moisture being carried from the Arabian Sea to northwest India.
The Indian Meteorological Department recorded above-normal rainfall in northwest India, including states like 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 percent 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," concluded Joseph.
This research highlights the complex and sometimes 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.
Full Research Paper: Increased Summer Monsoon Rainfall Over Northwest India Caused by Hadley Cell Expansion and Indian Ocean Warming - Joseph - 2024 - Geophysical Research Letters - Wiley Online Library
