CP RajendranFebruary 13, 2021 3:20:41 PM IST
The Himalayas is an active transcontinental mountain range in Asia, growing at a few millimeters per year. For millions and millions of years, a tectonic push at the rhythm of a snail has brought this mountain to its present imposing stature. As the jagged mountain peaks attest, the dynamic Himalayan landscape is also subject, in equal measure, to the erosive forces of climate that are constantly working to wear them down. In all its environmental and relief complexities, the Himalayas are the product of a dynamic balance between the invisible natural processes operating in the region and the stresses exerted by these forces or their agents, often in the form of earthquakes, avalanches and floods.
The Himalayas contain the largest volume of snow and ice outside of the polar regions. The “Third Pole”, as it is also known, has a huge deposit of glaciers, the point of origin of some of the major rivers in Asia. It is also a primary regulator of global climate in general, and of Asia in particular. One billion people living downstream of these rivers in China, India, Pakistan, and other Southeast Asian countries depend on the Himalayas and the Tibetan Plateau for their Water needs. With its transcontinental location running through the most populated part of the world, the Himalayas are now also subject to various anthropogenic forces. Scientific studies inform us that this third type of force, now recognized as the main driver of global warming, is impacting the natural balance and accelerating environmental change in the mountain range.
Ecosystem degradation based on temperature rise and consequent loss of ice in the Himalayas is directly related to long-term water availability for riparian countries in Asia, including India. The Himalayas contain the largest volume of snow and ice outside of the polar regions. Nearly 1 billion people living downstream in China, India, Pakistan, and Southeast Asia depend on the Himalayas and the Tibetan Plateau for Water. Recent projections indicate that the region around Mt. Everest may lose between 70% and 99% of the volume of glaciers by 2100 as a result of warming caused by greenhouse gas emissions. These findings portend an alarming situation.
The Himalayas, often considered the “third pole”, is vulnerable and a global hotspot for biodiversity. But the Nepalese government appears to have learned nothing new about conserving ecosystems, experts say. Image: NASA
But glacier ice losses have now reached an immediacy in the context of their possible connection to the increased frequency of flood hazards in the Himalayas. The devastating February 7 flood on the Rishiganga River in the Chamoli district of the Garhwal Himalaya was the latest example. Satellite images that covered the event, which were widely circulated in the media, indicate that the entire process began as a landslide of a rock and a large number of rocks descended with tremendous speed and landed on top of a hanging glacier ( in the Raunthi glacier area). , instantly transforming glacier ice into water. The water mixed with rocks and other debris descended, the pressure of the debris further squeezed the water-soaked sediment, causing an avalanche of water cascading down the river valley.
Unlike the Kedarnath flash flood of 2013, the Chamoli rock avalanche incident shows no evidence of a glacial lake rupture at the top of the mountain. Still, it is likely that both incidents are related at a fundamental level, by their triggering mechanism: the premature thawing of permanently frozen ice or so-called permafrost. Mountain permafrost is the ice in the crevices and crevices between rocks that hold them together and help stabilize steep slopes. If the melting of mountain permafrost, the glue that binds fractured rock to surface ice, is what triggers the destabilization of mountain slopes, then warmer overall temperatures in recent decades must have been the cause of its melting. Could this also be what is causing a higher frequency of slope breaking in recent decades, creating rock slides and rock avalanches in the Himalayas? In a similar event that took place on May 5, 2012, the Annapurna Mountains caused flooding in the Seti River, Kaski district of Nepal.
Rock avalanches start at higher elevations and slopes with more mountain permafrost are more susceptible to long-term changes in temperatures. These observations and hypotheses can be compared with additional data that will be collected in the future to see if they hold up. If warmer temperatures do indeed destabilize steep slopes in traditionally cold climate regions, there will be more high-risk areas for rock slides and rock avalanches in the future.
An aerial view of flood-ravaged Rudraprayag in Uttarakhand, after the devastating flood in June 2013. Image: PIB
According to a study that analyzed satellite data for the past 40 years, published in the journal Scientific advances As of June 2019, around 650 glaciers in India, China, Nepal and Bhutan are showing signs of retreat. The study identifies global warming as the reason for the melting and loss of glacial ice over a large area and confirms the role of global warming. Scientists have also alerted us to the retreat of some of the glaciers in the Uttarakhand Himalaya. A report published in 2018 by the Divecha Center for Climate Change, Bengaluru, indicates that the average temperature in the northwestern Himalayas has increased by 0.66 ° C since 1991, a much higher increase than the world average. The upper Himalayas became even warmer on average in the same period. Scientists from the Snow and Avalanche Studies Establishment (SASE) in Chandigarh also conclude that winters in the northwestern Himalayas have gotten warmer and more humid in the past 25 years.
According to Himalayan Climate and Water Atlas, published by ICIMOD, GRID – Arendal and the International Climate and Environment Research Center – Oslo (CICERO) in 2015, the Hindu Kush Himalaya is warming significantly faster than the world average. An ICIMOD study published last May also said that Nepal’s glaciers in the Dudh Kosi Basin, which is home to some of the highest mountain peaks in the world, including Mount Everest, had lost a quarter of their surface in the past three decades. Temperatures across the region are projected to rise between 1 and 2 degrees Celsius on average by 2050. The consensus is that global warming is already showing a visible impact in the Himalayas, but more field and based studies are needed. satellites to quantify these changes.
I must admit that I became a firm believer in glacier retreat after meeting a Buddhist monk on the eastern tip of Bhutan, on the border with India, a landlocked country in the eastern Himalayas. Walking alongside him in the mountains there a few years ago, he showed a group of us the glacial mountains in the distance, and he told us that the glaciers were receding. He has been observing these changes since his childhood, and this, I consider to be a credible report from the field.
CP Rajendran is an adjunct professor at the National Institute for Advanced Study, Bengaluru.
.
She is a freelance blogger, writer, and speaker, and writes for various entertainment magazines.