Snow-covered area near the Atal Tunnel in Manali on March 14, 2024. There is a gradual shift in snowfall occurrence pattern from winter months towards early summer months.
| Photo Credit: PTI
Himachal Pradesh is not just witnessing a reducing snow cover over the years, a gradual shift in snowfall occurrence pattern from winter months towards early summer months is also a noticeable phenomenon occurring in the hill State, raising concern surrounding climate variability in the ecologically fragile Himalayas.
The decrease in the snow cover during the peak winter months of December and January is especially worrisome and alarming as it could affect the water availability during summer as the snow that occurs during these peak winters sustains for a long time and enhances the discharge dependability of the major river basins during summer time.
The latest study conducted by the Centre on Climate Change of Himachal Pradesh Council for Science Technology-Environment (HIMCOSTE) has revealed that all the major river basins including Satluj, Ravi, Chenab and Beas in Himachal Pradesh have witnessed an overall decrease of 12.72% in area under snow in 2023-24 winters in comparison to 2022-23.
The study conducted using Advanced Wide Field Sensor (AWiFS) satellite data, also points out that during 2023-24, the early winter months of October-November were characterized by a decrease in snow cover area except Ravi basin which showed a marginal increase in the area under snow in October. Similarly, the peak winter months of December-January saw a negative trend in the area under snow. Notably, during the late winter months of February and March, the trend was observed to be positive with an increase in the area under snow in all basins against the last year.
In fact, during April the snow cover area increased due to fresh snowfall in the early summer period on higher mountain reaches in all the basins. As per the study, from October to January, there was less area under snow in all basins and the worst affected was January month when all basins saw a maximum decrease in the area under snow, indicating there was no snowfall at even at the higher reaches in the peak winter season.
“The total area under snow during 2023-24 [October-April] was decreased in the early half of winters i.e. October and November in all basins except Ravi reflecting a marginal increase, whereas the peak winter [December-January] shows drastic reduction in the area under snow especially the January in all basins except Satluj that reflects a marginal increase in December, whereas the later half [February-March] shows an increase in the area under snow in all basins. The late snowfall that extended to April this year has resulted in an increase in the area under snow, but the snowfall during this period may not be much useful as the rising temperature from April onwards may enhance the melting rate thereby affecting the discharge dependability of the major rivers like Beas, Chenab, Satluj and Ravi that depends upon the seasonal snow cover besides the glacier melt during the peak summer time,” D.C. Rana, director HIMCOSTE, said.
Environmentalists and scientists are concerned over the shifting of snowfall patterns from winter months to early summer months in the Himalayan State. S.S. Randhawa, a co-author of the study, said that the Centre has been assessing the spatial extent of seasonal snow cover in Himachal Pradesh since 2015-16, and it has been observed that by and large there has been a reducing trend in snowfall during the past decade. “The worrisome matter is that there is a gradual shift in snowfall occurrence pattern. The snowfall in peak winter is reducing slightly and is shifting towards the late winter months or even early summer months. There could be varied reasons behind it. Depleting snow cover and change in snowfall pattern should be an immediate concern for everyone as it would have an impact on hydro-power, water sources, people, livestock, forests, farms and infrastructure,” he said.
Himachal Pradesh Chief Secretary Prabodh Saxena said the shift in the snowfall patterns during winter could affect the river discharge during the peak summer season. “We have also seen the rising temperature effects during winters in Shimla, which had been experiencing almost negligible snow spells during the last two winters, indicating a major change in the weather patterns and if this continues, we have to think upon as we may have a shortage of water in the coming years,” he said.
