Northern winter storms in India now more frequent in summer, raise risk of heavy flooding: study

New Delhi, Mar 12 (PTI) Winter storms in north India are arriving significantly later in the year compared to 70 years ago, worsening risk of heavy flooding and threatening vital water supply to millions, new research has found.

"Some areas of Kashmir saw no snow at all in December or January. This is a serious concern for the 750 million people in the Indus and upper Ganges basins who rely on these winter snows for water supplies," said Kieran Hunt and a co-author of the study that was published in the journal Weather and Climate Dynamics.

"The loss of winter snow and the increasing late-season storms that heighten flood risks is a one-two suckerpunch that underscores the urgent need to respond to the far-reaching impacts of climate change in this sensitive region," he said.

The study found that the cyclonic storms, known as western disturbances, have become 60 per cent more frequent in summer from April to July.

Authors of the stud said these western disturbances typically bring heavy snow to the Himalayas from December to March and the slow melting of the snowpack in spring ensures a steady supply of irrigation water for wheat and other crops downstream.

However, arriving in the pre-monsoon heat, these increasingly frequent late-season storms unleash heavy rainfall instead of snow, raising risks of devastating flooding, the researchers said.

Meanwhile, as the region warms, winter snowfall is reducing, threatening spring water supplies, they said.

"Strong storms are now twice as likely to occur in the north of India in June compared to 70 years ago. With warmer and moister air at this time of year, these late storms are dumping heavy rainfall instead of snow," said Hunt, who is a researcher at the University of Reading in UK.

"This raises the risk of deadly flooding like we saw in Uttarakhand in 2013 and around Delhi in 2023," he said.

The study's authors attributed this seasonal shift to global warming and changes in the subtropical jet stream, a high-altitude air current that steers western disturbances.

Global warming is weakening the temperature difference between the equator and the poles that normally draw the jet stream northward in summer, they explained.

Further, the rapid warming of the Himalayan Plateau, lying at the intersection of Central, South and East Asia, is fuelling a stronger jet stream that powers more frequent and intense storms, the team explained.

They said that as a result, the jet stream is increasingly lingering at southern latitudes later into spring and summer, allowing more storms to strike North India after the winter snow season.

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