New Delhi: Seven Indian states have been showing a declining trend in annual rainfall over the last 30 years, the Times of India reported on Monday.
Madhavan Rajeevan, the secretary of the Ministry of Earth Sciences (MoES), has attributed the trend climate change.
The MoES had been tasked by the parliamentary committee on science and technology, environment, forests and climate change, headed by Jairam Ramesh, to provide information on changing rainfall patterns and the consequent implications for agriculture.
So the ministry analysed data spanning 30 years of rainfall patterns around the country during the monsoon months, as well as annual rainfall and rainfall intensity in all states.
It concluded that Bihar, Meghalaya, Nagaland, West Bengal and Uttar Pradesh show “statistically significant decreasing trends” in monsoon rainfall.
In addition to these five states, Himachal Pradesh and Arunachal Pradesh have shown statistically significant decreasing trend in annual rainfall, implying that winter rain has been on the down in the two Himalayan states.
“It could be attributed to climate change. Global warming is happening and it has impacted the climate in India as well,” Rajeevan told the newspaper. “As a result, many parts of the country have seen decreasing trends while others witnessed increasing trends.”
The MoES has also told the parliamentary committee that the frequencies of dry days, rainy days (daily rainfall of 2.5 mm or more but less than 7 cm) and heavy rainfall events (rainfall greater than equal to 7 cm) have changed.
“The situation for agriculture or water recharges in the states in the Ganga basin, [namely] Delhi, Uttar Pradesh, Bihar and West Bengal, and some other states … is alarming as the number of dry days during southwest monsoon is significantly increasing and also the frequency of rainfall of lower intensities favourable for soil and groundwater recharge is decreasing over these regions,” the ministry said in a submission to the parliamentary committee.
Human-induced climate change has been causing widespread changes to weather patterns in India. A 2019 review of studies on the summer monsoon concluded that rainfall has declined in certain parts and risen in other parts. But overall, the monsoons appear to be weakening in the long term.
“The strength of the monsoon has weakened,” Deepti Singh, an assistant professor at the Washington State University in Vancouver, Canada, and one of the authors of the review, told The Wire in September 2019. “The total amount of rainfall has been declining in [central India].”
Climate models predict that the number of extreme rainfall events will rise in the Indian subcontinent as the impact of warming increases. The number of days with extreme rainfall and the number of days with no rainfall will both increase, as the MoES study indicates. These patterns are expected to become entrenched with climate change.