Gangotri glacier lost 0.23 sq km in 15 years, Centre informs Rajya Sabha
In the higher reaches of the Himalayas, warming of glaciers was recorded at the rate of 0.5 degree Celsius, much higher than the average warming experienced over the entire country
NEW DELHI: The Gangotri glacier in Uttarakhand has lost approximately 0.23 square kilometre area in 15 years and the Indian Space Research Organisation (ISRO) is monitoring the changes using Indian Remote Sensing Satellite data, Union environment minister Bhupender Yadav informed Rajya Sabha on Thursday.
“As per the information received from ISRO, it has been observed that Gangotri glacier has lost approximately 0.23 sq km area due to the retreat of the glacier in the 15 years’ time frame from 2001-2016,” Yadav said.
Yadav’s statement was in response to a question by Mahesh Poddar of the Bharatiya Janata Party, who sought to confirm reports that the glacier was melting due to the alleged presence of black carbon in the atmosphere, and know the extent to which the glacier has been melting/retreating in the past two decades. He also asked about the measures being taken by the government to protect habitations in the lower valleys.
The extent to which the Himalayan glaciers have retreated is a complex and evolving subject studied through investigation, data collection and analysis of various case studies by scientists in India and all over the world, Yadav said, adding that the glaciers and their characteristics exhibit complex changes in specific locations, such as various sub-regions in the Himalayas.
“There are stable, retreating or even advancing glaciers in the Himalayas, thereby, emphasising the complex geographical and cyclical nature of the glacial dynamics. The literature suggests that the Himalayan region has experienced the presence of black carbon. However, its effect on mass loss and retreat of the Gangotri glacier has not been studied,” the minister told the House.
Black carbon has emerged as a major contributor to global climate change, possibly second only to carbon dioxide, as the main driver of change. Black carbon particles strongly absorb sunlight, giving soot its black color. It is produced both naturally and by human activities as a result of incomplete combustion of fossil fuels, biofuels, and biomass.
According to information received by the environment ministry from ISRO, in situ measurements show a variable concentration of black carbon over the Himalayan region, with very low values (~ 60 to 100 ng m-3) over the western Himalayas, moderate values over the eastern Himalayas (~ 1000 to 1500 ng m-3), and high values over the foothills of the Himalayas (~ 2000 to 3000 ng m-3).
“Black carbon is a short-lived climate pollutant, with a lifetime of only days to weeks after its release into the atmosphere, especially over the Himalayas that experience periodic snowfall. Moreover, Himalayan glaciers have a high concentration of debris on ice and dust on snow, significantly reducing the effect of the changing reflectance of snow and ice on the glaciers. Due to this, the impact of black carbon on Himalayan glaciers is not of a substantial magnitude,” Yadav said.
“The story of Gangotri glacier is not different from many other glaciers. If you look into some of the earlier replies in Parliament, this glacier has been retreating since the Little Ice Ages. The Geological Survey of India has been monitoring its retreat since 1870 and its rate of retreat had accelerated in the ’60s and ’70s. After that, it has been consistently retreating. Most of the glaciers in the Himalayas are retreating essentially because of an increase in temperature due to climate change. Our publication has suggested that the rate of increase in temperature is much higher than the global mean. There has also been more rainfall in recent decades than snowfall. So, most glaciers are impacted, except for some exceptions in Karakoram. But even those glaciers with positive or balanced mass balance will not see the trend for long. It is a matter of time when the Karakoram anomaly vanishes,” professor Anil Kulkarni, a distinguished scientist at the Divecha Center for Climate Change, said.
“Different regions of Himalayas have different stories of glacial loss. Many things are not said in Parliament answers which we should understand. There is no study on how black carbon is impacting glacial mass balance. The Gangotri glacier gets rainfall in both summer and winter, which is why the impact of black carbon on Gangotri may be negligible. But that doesn’t mean black carbon is not affecting the cryosphere. The impact of black carbon needs to be studied very well,” Kulkarni added.
‘Assessment of Climate Change over the Indian Region’, a ministry of earth sciences document modelled on the Intergovernmental Panel on Climate Change’s assessment reports that sources scientific evidence on climate change globally, flagged in 2020 that the Himalayas and the Tibetan plateau recorded warming of 0.2 degree Celsius per decade between 1951 and 2014. In the higher reaches, the warming was recorded at the rate of 0.5 degree Celsius, much higher than the average warming experienced over the entire country.
The Hindu Kush Himalayas (HKH) recorded a temperature rise of about 1.3 degrees Celsius from 1951-2014 compared to an average temperature rise of around 0.7 degree Celsius over the country from 1901-2018. This has led to several areas of HKH recording a steep decline in snowfall and retreat of glaciers in recent decades. The high-elevation Karakoram Himalayas, however, has experienced higher winter snowfall, and hence, far less glacial retreat.
“There is now consensus that most glaciers in the Himalayas are retreating, with the pace accelerating from the beginning of the 21st Century. As several studies have shown, warming is much higher in the upper reaches of the Himalayas, with loss of glaciers and lake formation increasing. These lakes can burst and cause flash floods. There are a number of mechanisms through which such floods can happen in association with landslides and avalanches. We have also monitored glacial lake formations in the Alaknanda basin and the Nanda Devi glacier,” Kulkarni earlier said following the glacial overflow on February 7 last year that triggered a flash flood and swept away two hydroelectric plants in Uttarakhand’s Chamoli district, killing over 200 people.
The Department of Science and Technology (DST) is implementing the National Mission for Sustaining the Himalayan Ecosystem (NMSHE) and the National Mission on Strategic Knowledge for Climate Change (NMSKCC) under the National Action Plan on Climate Change (NAPCC). Under NMSHE, state climate change cells/centres (SCCCs) have been established in 12 Himalayan states/Union territories — Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Arunachal Pradesh, Nagaland, Manipur, Meghalaya, Mizoram, Tripura, Sikkim, West Bengal and Assam.
These SCCCs have been mandated to provide assistance to states/UTs to take up vulnerability and risk assessment, capacity building programmes and public awareness programmes to address sustenance of the Himalayan ecosystem, Yadav said.