As winter storms arrive later in the year, North India faces dual threat of water scarcity and flooding

The recently concluded winter of 2023-24 was a particularly dry one for North India. The region barely witnessed any snowfall until the end of January, painting an unusual picture marked by the absence of pristine white landscapes that typically cloak the majestic Himalayas.

This dry spell was down to the delayed arrival of winter storms — an ongoing trend that is raising concerns over dwindling water resources and potential flooding for millions of Indians!

Beyond the Season: Winter Storms' Delayed Summer Appearance

Winter storms, technically known as western disturbances, are warm, moisture-laden winds that begin their journey over the Mediterranean Sea. As they waltz across continents, gathering moisture from the seas they encounter, they eventually reach the mighty Himalayas. There, amidst the towering peaks, they unleash the payloads and shower the land below with a mix of rain and snow.

Traditionally, these winter storms have graced the Himalayas with abundant snow from December to March, ensuring a steady flow of water supply downstream. However, new research has unveiled a shift in these patterns, with western disturbances now arriving fashionably late compared to seven decades ago.

Published in the journal Weather and Climate Dynamics, the study highlights a surge in western disturbances during India's summer months. Over the past 70 years, these unexpected guests have increased in frequency by 60% from April to July, reducing snowfall and increasing the risk of heavy flooding reminiscent of the calamities we saw in Uttarakhand in 2013 and around Delhi in 2023.

The research team attributes this seasonal shift to changes in the subtropical jet stream, a high-altitude air current steering western disturbances. The warming of the Tibetan Plateau, a vast expanse at the crossroads of Central, South and East Asia, is amplifying temperature contrast with surrounding areas, creating a stronger jet stream that powers more frequent and intense storms.

In tandem, global warming is weakening the temperature difference between the equator and poles, disrupting the traditional northward migration of the jet stream in summer. As a result, the jet stream is increasingly lingering at southerly latitudes later into spring and summer, allowing more storms to strike North India after the typical winter snow season has passed.

Precipitation Perils: The Dual Challenge of Dwindling Snowmelt and Flooding

As the regular occurrence of these late-season storms coincides with the setting-in of pre-monsoon heat, North India is likely to be lashed by torrential rainfall rather than snowfall. This shift in precipitation patterns poses a heightened risk of severe flooding, which could lead to devastation for communities and ecosystems alike.

Concurrently, the decline in winter snowfall mirrors the warming trend in the region, jeopardising vital spring water supplies. With less snow accumulating in the mountains during winter, there is a diminished reserve of meltwater to replenish rivers and streams come springtime. This threatens agricultural activities and water availability for households, disrupting the delicate balance of ecosystems that rely on seasonal water flow as well as the traditional rhythms of life and livelihoods in the region.

Study author Dr. Kieran Hunt of the University of Reading adds: “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.

He describes the loss of winter snow and the increasing late-season storms as a “one-two punch” that underscores the urgent need to respond to the far-reaching impacts of climate change in this sensitive region.