India's monsoon-the lifeblood of Asia's third-largest economy-is drying up because of air pollution over European countries, according to a new study in the journal Science, findings which have been treated with caution by the Indian Met department.
The study, by professor Yi Ming and his colleagues at Princeton University and also reported by the NewScientist, squarely blames aerosols, or tiny specks of matter that can be found all over the Earth's atmosphere and commonly associated with spray cans.
Local air pollution, traditional fuels and other pollutants have been previously blamed for cooling surface temperatures in South Asia, causing less evaporation and summer rainfall, but the Princeton study has for the first time linked factors in another continent to the quality of India's monsoon.
India's Met chief Ajit Tyagi said pollution is known to impact climate but added that his department had no evidence to conclude that monsoon falls had decreased over the past half century.
"The mean rainfall over the last 50 years has shown no decrease according to our observations. So, we cannot immediately corroborate this study," Tyagi told HT.
In 2009, India suffered its worst drought in three decades, shrinking farm output and increasing food prices sharply.
The monsoon results from large scale wind patterns that transfer heat between the northern and southern hemispheres. As the winds traverse the Indian Ocean during the northern hemisphere's summer, they draw moisture and result in the summer rains.
Aerosol haze over Europe in summer has been preventing adequate heating of the northern hemisphere, compared to the southern hemisphere, leaving the winds less forceful - and the Indian monsoon less vigorous, the new study found.