New Delhi, Sept. 10: Rainfall patterns have changed in India with some regions turning drier and others wetter, triggering fresh speculation whether recent deviant weather might be signals of climate change.
Scientists at the National Climate Centre (NCC) in Pune, who have completed the most comprehensive analysis so far of Indian rainfall over the past century, have reported “significant and remarkable” variations on a regional scale.
A research report prepared by the NCC, now in circulation within the scientific community, says Jharkhand, Chhattisgarh and Kerala show significant decreasing trends in monsoon rainfall.
The report, a copy of which was made available to The Telegraph, also says monsoon rainfall is showing significant increasing trends in places such as Gangetic Bengal, western Uttar Pradesh, Jammu and Kashmir, Konkan and Goa.
But scientists caution that there is no evidence to link the changes to global climate change.
“We know that the average temperature in India has increased by 0.6 degrees,” said Madhavan Rajeevan, NCC director and co-author of the report. The decrease in monsoon rain over Jharkhand and Chhattisgarh is significant — up to 10 per cent, he said. These regions also account for the highest rise in temperature in India: about one degree.
“But, for the moment, we cannot connect the regional changes in rainfall to the temperature rise,” Rajeevan said.
Climate researchers say monsoon rainfall has natural fluctuations which occur over years and decades that can interfere with the effects of climate change. “It’s a nightmare to separate these fluctuations from long-term changes that might be happening,” said Professor Sulochana Gadgil at the Centre for Atmosphere and Oceanic Sciences at the Indian Institute of Science, Bangalore.
Rajeevan and his colleague P. Guhathakurta analysed rainfall data from 1,476 stations in 524 districts from 1901 to 2003 to figure out whether rainfall patterns have changed.
Their study has shown that for the country as a whole, the monsoon rainfall doesn’t show any significant trend. The average monsoon rainfall of 877 mm makes up about 74 per cent of India’s total rainfall of 1,182 mm. But changes are happening within the season and regionally.
The contribution of July rainfall is decreasing in central and western peninsular India, the analysis revealed. But rainfall in August is increasing in all these meteorological zones.