Changes in western disturbances may adversely affect food security, crop productivity
Summary
Western disturbances are crucial for winter precipitation in northern India, but their changing patterns could lead to reduced crop yields and increased irrigation costs.The frequency and nature of western disturbances in India has changed over the past few years, a development that could adversely affect agriculture and food security, the top official of the country’s weather office said.
Western disturbances—moisture-laden storms originating in the Mediterranean—play a crucial role in bringing rain and snowfall to the northern states of Punjab, Haryana, Rajasthan, Uttar Pradesh and Jammu and Kashmir in winter. Wheat and mustard are among the key winter crops cultivated in some of these states.
“The reduction in their frequency or intensity in winters is a matter of concern," M Mohapatra, Director General of the India Meteorological Department (IMD), said in an exclusive interview with Mint.
These systems are essential for maintaining winter precipitation, glacier mass balance, and overall water availability that supports rabi crops such as wheat and mustard. Studies have shown that climate change has led to snow melting earlier across the western Himalaya and the Hindu Kush and this has had a negative impact on rabi crop production and ecosystems.
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Agricultural experts said diminished winter precipitation could reduce soil moisture, cut crop yields and increase reliance on irrigation. This would not only drive-up input costs for farmers but also risk impacting India’s food grain output. Productivity of wheat, a key rabi crop, could drop in the absence of sufficient winter rain, with consequences for procurement and price stability.
"If the momentum of western disturbances reduces in winter further, then it can impact irrigation which can further have a cascading impact on agriculture productivity," a senior agricultural scientist said on condition of anonymity.
Prolonged season
Additionally, the season for such storms appears to have extended beyond the winter months, raising questions about how climate change is affecting the frequency and intensity of western disturbances in both the summer and winter seasons.
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According to a research paper by Kieran MR Hunt of the Department of Meteorology at the University of Reading in the UK, western disturbances, which usually occur during the December to March period, are becoming far more common in May, June and July, months when they were previously rare. These storms have been twice as common in June in the past 20 years than they were during the previous 50, suggesting that the season for western disturbances has lengthened.
The impact of such changes was felt in and around New Delhi earlier this month. The intense thunderstorm accompanied with squally/gusty winds and heavy rainfall that hit the National Capital Region on 2 May was on account of a western disturbance, according to the IMD. Delhi (Safdarjung) recorded 77mm rainfall on 2 May, it said. That was the second-highest 24-hour rainfall recorded in Delhi in May since 1901.
According to meteorologists, the passage of back-to-back western disturbances has brought with them heavy rainfall spells across the hilly states. Following heavy rains and thunderstorms, flash floods and landslides wreaked havoc in several parts of Jammu and Kashmir, parts of Himachal Pradesh and Uttarakhand in April.
On the other hand, the arrival of these systems at a regular interval has kept prolonged heat waves away from the northwestern plains so far. Changes in the western disturbances system have made the Himalayan states more vulnerable to extreme weather events, directly linked to climate change.
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According to the Intergovernmental Panel on Climate Change’s 6th Assessment Cycle’s Working Group 1 report in 2021, most of the Hindu Kush Himalayan region’s snow cover has reduced since the early 21st century, and glaciers have retreated and lost mass since the 1970s.
The Karakoram glaciers have remained either in a balanced state or have slightly gained mass. During the 21st century, snow-covered areas and snow volumes will decrease in most of the Hindu Kush Himalayas and the snow line elevation will rise as glacier volumes decline, according to the report.
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