Himachal Pradesh, a state that has five important perennial rivers fed particularly by glaciers, has witnessed a decline in snowfall over the past year. The area under snow cover in the state has declined by 18.5% between 2019-’20 and 2020-’21 according to a report by the State Centre on Climate Change Shimla and Space Application Centre of the Indian Space Research Organisation in Ahmedabad.
The study revealed that the area under snow cover in 2019-’20 was 23,542 sq km, which dropped to 19,183 sq km in 2020-’21, a decline of 3,404 sq km or 18.52%. Usually, in the winter season, about one-third of the geographical area of the state, which amounts to about 18,556 sq km, remains under thick snow cover. Most of the major rivers like Chenab, Beas, Parvati, Baspa, Spiti, Ravi, Sutlej and their perennial tributaries originating from the Himalayas depend upon the seasonal snow cover for their discharge dependability.
SS Randhawa, the principal scientist at the State Centre on Climate Change, who headed the study team, said, “Considering the importance of snowfall in the region, we did this study by analysing the data from satellites.”
“We observed a shift in snowfall patterns in the last few years and snow cover is continuously declining,” Randhawa said. “We also observed a decreasing trend in four river basins of the state which put long-term implications on water availability in the river basins.”
Falling snow cover
The report added that the snow cover in the Chenab basin fell from 7,154 sq km in 2019-’20 to 6,516 sq km in 2020-’21, a reduction of 638 sq km or 8.92%. The Beas basin shows a decrease of about 19% with its average snow cover area having decreased from 2,458 sq km to 2,002 sq km, a loss of 455 sq km. The Ravi basin saw an overall reduction of 23% in the total area under snow cover.
The snow cover in the Sutlej Basin, which covers 45% area of Himachal and is the longest river in the state, shrunk the most by 23.49% or 2,777 sq km. It was 11,823 sq km in 2019-’20 and 9,046 sq km this year.
Another study published in 2019 said that the Sutlej River basin glaciers are melting fast and may shrink significantly by as soon as 2050. The research estimates that the melting would cause 33% of the glaciers to disappear by 2050 and 81% by the end of the century.
Surender Paul, head of the Indian Metrological Department, Shimla, said, “The winters in the northern hemisphere are defined by downward winds from the North Pole. Polar Vortex, a low-pressure area lying at Earth poles, is strong due to which the intensity of jet streams and western disturbances is less in the northern hemisphere including India.”
“Apart from this, the jet streams and western disturbances are moving at higher altitudes due to which low lying areas do not get much snowfall,” he added. “Global warming is warming the poles, thus also impacting Polar Vortex and jet streams. As a rising global temperature warms poles quicker than the rest of the world, the temperature contrast that drives jet streams has decreased which is the main cause for the lack of snowfall.”
Not only Himachal, glaciers in Jammu, Kashmir and Ladakh are also melting at a significant rate. According to a 2020 study, over 1,200 glaciers in the region saw an annual reduction in mass of 35 centimetres on average between 2000 and 2012. The study added that the glaciers have reduced from 102 sq km in 1980 to 72 sq km in 2018 showing a recession 28.8% decrease.
Irfan Rashid, Senior Professor, Department of Geoinformatics, University of Kashmir, said, “From 1980, at least six glaciers have disappeared. Four out of the six disappeared after the year 2000. The main reason is climate change; but other factor includes an increase in greenhouse gases like carbon dioxide, methane, nitrous oxide and fluorinated gases. India stands at the third position after China and the United States in the release of greenhouse gases.”
Rashid also studied the Kolahoi Glacier in Kashmir and concluded that the glacier has lost 23% area since 1962 and has fragmented into smaller parts. Satellite data from another study published this September revealed a 29% loss in the area of Machoi Glacier from 1972 to 2019. The glaciers like Machoi, Kolahoi and Thajiwas are the major source of water for rivers. Irfan asserts that the decline in glaciers increased the runoff of rivers in Kashmir.
According to the state of Jammu and Kashmir Rivers Report, during the last 51 years, the glacier area in the Jhelum basin has decreased from 46.09 sq km in 1962 to 33.43 sq km in 2013, a decline of 27.47%. The glacier area of river Chenab has also seen a decline of 21%.
In Uttarakhand, there has been a downfall of around 85 sq km of the snow cover of the Gangotri and surrounding glaciers in the years of 2018 and 2019 respectively from the year 2017, according to a study that used Remote Sensing and Geographic Information System. In 2020, a huge recovery has occurred with a drastic increase in snow cover area by approximately the same amount which has been previously depleted. After 2020, a gradual drop of 27 sq km occurred in 2021.
The Ganges River system in the Indian Himalayas can be divided into four major river basins ie the Yamuna, Bhagirathi, Alaknanda and Ghaghara River Basins. The Ganges River system remains the main source of fresh water for half the population of India and Bangladesh and nearly the entire population of Nepal. Reports also mention a decline in snow cover of the Brahmaputra basin.
DP Dobhal, a glaciologist from Wadia Institute of Himalayan Geology said, “There is no denying the fact that winter warming in the Himalayas is on the rise due to which the glaciers in the area are depleting at a rapid pace. Gangotri glacier has declined 63 metres in last 360 years.”
According to a release shared by the Ministry of Science and Technology, snow and glaciers are melting rapidly in the Himalayan range due to climate change, altering water supplies in the rivers like Indus, Ganga and Brahmaputra in the Himalaya-Karakoram ranges. Total river runoff, glacier melt and seasonality of flow in these rivers are projected to increase until the 2050s, with some exceptions and large uncertainties, according to a study Glacio-hydrology of the Himalaya-Karakoram.
“The Himalayan river basins cover an area of 2.75 million sq km and have the largest irrigated area of 577,000 sq km, and the world’s largest installed hydropower capacity of 26,432 megawatts,” said Mohd Farooq Azam, assistant professor at the Indian Institute of Technology Indore, in the study. “The melting glaciers fulfils the water requirements of more than a billion people of the region who will be affected when much of the glacier ice mass melts throughout this century and gradually stops supplying the required amount of water.”
The melting of glaciers is linked to various disasters. The melting of glaciers can lead to landslides, avalanches and glacial lake bursting. The State Centre on Climate Change indicated in 2019 that the glacial lakes are increasing in Himachal Pradesh which can pose a threat of flood in downstream areas. The Sutlej basin has 562 lakes (the highest among the five basins) followed by, Chenab, Beas and Ravi basins with 242, 93 and 37 lakes respectively, the State Centre on Climate Change noticed.
This year, the Indian Himalayas saw many glacier bursts, landslides and avalanches. A flood in Uttarakhand’s Chamoli left nearly 200 killed or missing. In Himachal and Uttarakhand, landslides are wreaking havoc for the past few years. The scientists accused glacier melting as one of the reasons behind the disasters.
“When ice melts, it gives a space to landslides,” said GCS Negi, Scientist, GB Pant National Institute of Himalayan Environment and Sustainable Development. “This year, whether it is a flood by glacier burst in Chamoli, Joshimath or an avalanche, the glacier melt is the sole reason for that. We have warned of all this.”
“Nanda Devi glacier receded 26 sq km in last 37 years while Raunthi peak declined by 800 metres in 25 years,” said GCS Negi. “Both glaciers burst this year taking several lives. Historically, any impact on glaciers is followed by disasters.”
Recently, researchers have reported that the glacier had abruptly changed its main course in Uttarakhand. It is for the first time that such change in course has been reported from a Himalayan glacier and the researchers have attributed this to the accumulated influence of both climate and tectonics.
The researchers attributed the disaster in Rishiganga as the latest example which suggests that the rock mass on which the glacier was sitting gradually became fragile due to weathering, percolation of meltwater in joints, crevasses, freezing and thawing, snowfall, overloading and gradually operating tectonic forces forcing rocks to mechanical disintegration with due course of time and detached from the source rock.
“It is important to understand that mountain communities are bearing the immediate impacts of flash floods induced by glacial melts,” questioned Manshi Asher, co-founder of Himdhara Collective. “These impacts are further exacerbated by large infrastructure projects which are why in states like Himachal, Uttarakhand and Sikkim – there is opposition to big dams. Why should the responsibility of protecting the glaciers and rivers, forests in the catchment, lie only with the mountain people.”
Further, she added, “The rivers from Himachal feed into the Indus river system. Uttarakhand and northeast glaciers are responsible for the Ganges and Brahmaputra river systems respectively.”
“Such a decline in glaciers will impact water availability for nearly 13% of the global population,” she said. “The water and food security of billions of people will be impacted. The affected persons will also include those in the megacities like Delhi and Kolkata in India, Lahore and Karachi in Pakistan and Dhaka in Bangladesh and Nepal.”
This article first appeared on Mongabay.