Glacier studies in Ladakh, Himachal Pradesh flag stark climate change impact
For the Ladakh study, published in the Journal of Glaciology on May 18, the team found that the Stok glacier is facing as much mass loss as its western Himalayan counterparts, despite being in a higher altitude zone between the Himalayan and Karakoram mountain ranges.Updated: Jun 30, 2020 11:52 IST
Climate change is having a discernible impact on glaciers in the western Himalayan region, studies by Jawaharlal Nehru University’s (JNU) glaciology unit in the School of Environmental Sciences has found.
The results of their long-term monitoring of two glaciers, based on observational data and modelling exercises, in Himachal Pradesh (HP) and the Union Territory of Ladakh, have found that in the first decade of the new millennium glacier mass loss was significantly higher than in the late 20th century.
While the glaciers will not disappear in the coming decades, the authors of the studies said, negative mass balance -- the net change in its mass over a balance year or fixed year -- of these slowly moving giant mass of ice is likely to have a profound impact on water availability for local communities.
They also said that mass loss in glaciers in the region is mainly linked to rising temperatures and reduced snowfall.
For the Ladakh study, published in the Journal of Glaciology on May 18, the team found that the Stok glacier is facing as much mass loss as its western Himalayan counterparts, despite being in a higher altitude zone between the Himalayan and Karakoram mountain ranges.
The Stok glacier was in a balanced condition during the late 20th century -- around the 1980s --- due to sufficient winter precipitation, or snowfall. However, it was followed by a severe loss during the early 21st century -- prior to 2009 -- and a moderate loss after 2011.
“This is mainly because of reduced winter snowfall in the arid Himalayan region. This must be also affecting water availability in villages in and around Stok and Indus river, which must be studied,” said JNU’s Professor AL Ramanathan, the corresponding author of the paper.
The paper projects that a 27% increase in snow or rain is required to compensate for the mass loss due to 1 degree Celsius rise in temperature over pre-industrial era levels.
“Accelerated temperature rise over the western Himalayas has significantly reduced the amount of snowfall received and also aggravated glacier mass loss,” he added.
Another paper published in the same journal on June 23 is a study -- conducted between 2002 and 2019 --- of the Chhota Shigri glacier in HP.
The team found over the past two decades, on average half a metre of water equivalent of ice has been drained from this glacier in the Indus river.
The glacier is in an imbalanced condition because it has melted more than gained, the paper said.
“Overall, the air temperature change is controlling the river run-off, which means a warmer world is likely to be associated with higher water in the Himalayan rivers till the 2050s, which other studies have also observed. There might be a seasonal shift in glacier run-off as well,” Ramanthan said.
The country’s first national climate change assessment by the Union Ministry of Earth Sciences published in early June also flagged similar concerns.
For instance, the Hindu Kush Himalayas (HKH) region experienced a temperature rise of about 1.3 degrees Celsius between 1951 and 2014, as compared to an average temperature rise of .7 degree over India from 1901 onwards.
Several areas of the HKH region have experienced a declining trend in snowfall and also a retreat of glaciers in recent decades.
“Several areas in the HKH region have exhibited declining trends in snowfall and retreating glaciers during the recent decades. Parts of the high-elevation Karakoram Himalayas have, in contrast, experienced increased wintertime precipitation in association with enhanced amplitude variations of synoptic western disturbance,” the assessment has said.
“There are thousands of glaciers in the western Himalayas. It’s difficult to say how water availability will be impacted in the coming years. We need large observational and satellite studies to have an effective assessment. But reduced snowfall in recent years is linked to an overall trend of glacial retreat,” said Anil Kulkarni, Distinguished Scientist, Divecha Centre for Climate Change, Indian Institute of Science (IISc), Bengaluru.