Glaciers In Retreat
The Himalayas, with an estimated 475 small and large glaciers, is the largest reserve of water in the form of ice and snow outside the polar regions. What will happen to this ecosystem and the subcontinent when the glaciers melt faster than ever before and unleash these vast water reserves? Freny Manecksha searches for an answer
The release of a paper in November 2009 by VK Raina, former deputy general of the Geological Survey of India, stating there is no conclusive evidence to show that melting Himalayan glaciers pose a serious threat, may have been to “stimulate discussion”, in the words of Union Environment Minister Jairam Ramesh. But, for the people of Ladakh, such facile talk cuts no ice. They have been directly impacted by the faster rate of melting glaciers and have seen their livelihood threatened by climate change.
Says 73-year-old Chewang Norphel, a retired engineer who works on creating artificial glaciers as a water-harvesting method: “We have been witness to glaciers disappearing and to the volume of water in the Indus river reducing by as much as two-third. This affects us since 80 per cent of Ladakhi farmers depend on glaciers for irrigation.”
Tundup Angmo works with GERES India, a non-profit organisation working on issues of environmental conservation and climate change and mitigation. She says that analysis of meteorological data, baseline surveys and interviews with villagers have shown that, increasingly, minimum winter temperatures are up by one degree Celsius. “There is a clear declining trend in precipitation from November to March (that is, a reduction in snowfall) and villagers have spoken about the impact of this on glaciers in the Khardungla and Stok Kangri region,” she says.
Ladakhis also say that the duration of the “Chaddar trek” in Zanskar is getting shorter. The trek over a frozen sheet of ice that forms over the rivers and streams was once the only way for villagers of Zanskar to cross from one valley to another in winter when all other routes are closed due to the heavy snowfall.
Climate change is still a very nascent science and though there is enough anecdotal and documentary evidence to show that Himalayan glaciers have been impacted by global warming, there are very few benchmark studies on small glaciers.
One glaciologist who is spearheading a study on how glaciers are reacting to climate variations and how black carbon aerosols are affecting water resources is Professor Syed Iqbal Hasnain of The Energy and Resources Institute (TERI). Hasnain is studying four glaciers — Durung in the Zanskar basin, Kolahoi in Kashmir, Chhota Shigri in the Chandra Valley of Himachal Pradesh, and East Rathong in Sikkim. Since the terrain is rough and inaccessible, as the glaciers lie between 4,000 and 6,000 metres above sea level, Hasnain and his team are using the expertise and assistance of mountaineers to place and fix equipment.
Another study, Witnessing Change: Glaciers in the Indian Himalayas, by Dr Rajesh Kumar of the Birla Institute of Technology, Divya Mohan and Shirish Sinha of the World Wide Fund for Nature (WWF), is carrying out research on the retreat patterns of the 30-km-long Gangotri glacier and the smaller 4.2 km Kafani glacier in Uttarakhand.
What is the kind of data that glacier studies can yield? Why are such studies crucial in monitoring climate change? Glaciologists explain that glaciers (dynamic rivers of ice), which are a result of accumulation and transformation of snowfall over a number of years, are very vulnerable and fragile and react in a complex way to climate variations. A glacier stores information of past climates in the ice in the form of enclosed air bubbles, layers of dust, and ice chemistry.
Studies on the length, breadth, mass balance and growth/shrinkage of glaciers are visible indicators of how healthy the glaciers are. There is a line of snow accumulation that demarcates the zone above which no melting takes place. When the accumulation area ratio (AAR) begins to shrink, one knows that the glacier is in recession (it is decreasing in length).
Hasnain, in his interaction with environmental journalists in Leh recently showed a photograph of Kolahoi in 1942 that he had been able to procure from the long-established Mahatta Studios in Srinagar. Comparison with a current photograph of Kolahoi shows that the glacier’s accumulation area has indeed shrunk.
Hasnain believes that a glacier is like a thermometer. It is sensitive to the climatic environment and through calibrations and adjustments glaciologists can define the local relation between mass balance and the climate. Glacial networks, if monitored properly, can thus become important tools for mapping spatial and temporal climate and climate change.
Glaciers are also widely recognised as being sensitive climatic indicators. Measuring glacier evolution gives insights into regional climate changes in high and remote regions. This is of particular interest in the western Himalayas that receive snow and rainfall from both the monsoons and the westerlies. A weather station that has been set up by Hasnain’s team on the Kolahoi glacier will measure input to see how the westerlies affect precipitation.
Historically, glaciers have undergone changes over long periods of time, but it is the rapid rate of glacial retreat in the 21st century that is alarming scientists. It is now widely accepted that anthropogenic causes have most likely committed the earth to a warming of 2.4 degrees C above pre-industrial surface temperatures. This is impacting the glaciers.
The WWF study lists the findings of studies on some important glaciers by glaciologists and scientists. According to a study by D P Dhobal, glaciologist with the Wadia Institute of Himalayan Geology, Dehradun, the 5.5 km Dokriani glacier in Uttarakhand has been continuously retreating, with slight increases in the retreat rate, by 1m/year in the 1990s as compared to the average rate in the previous years. This has led to a reduction in thickness, from 55 m in 1962 to 50 m in 1995.
The Milam glacier, also in Uttarakhand, is one of the largest valley-type glaciers in the Kumaon Himalayas and it has been monitored since 1906. Recent studies suggest it is in a continuous state of recession. Since 1906, it has retreated by about 1,740 m with the average rate being 19.1 m per year. The increased rate of recession in the second half of the 20th century is being attributed to global warming (these findings were presented by S P Shukla and MA Siddiqui in 1999 at a symposium on “Snow, Ice and Glaciers, A Himalayan Perspective”, in Lucknow, in 1999).
The WWF study says that the Gangotri glacier is not only receding in length but also in terms of glaciated areas from all sides. The length of the glacier has decreased by almost 1.5 km in 66 years, with an average retreat rate of 22.1 m per year. However, because of its size it is less likely to show signs of change than smaller glaciers, the study says.
It adds: “The smaller Kafani glacier is more affected by climate change than the Gangotri because of its smaller accumulation area. Its tributary glacier is now hanging, that is, it is not directly connected any more through an ice mass to the main trunk of the glacier. This indicates loss of huge ice volumes in the glaciated catchment of Kafani.”
Professor Hasnain’s study, besides studying the health of the glaciers, also entails taking samples to assess concentrations of black carbon and setting up aethnometers to measure these major short-lived warming pollutants. He has been influenced by Professor V Ramanathan’s paper on the “Atmospheric Brown Cloud” which explains how greenhouse gases like CO2 swaddle the earth like a blanket trapping heat. Ramanathan says that in addition to greenhouse gases there are other climate warmers like methane, halocarbons and black carbon soot which rises and envelopes the atmosphere in a haze. It is eventually washed out of the sky by rainfall but not before it has travelled far enough to darken the glaciers.
The Himalayas, with an estimated 475 small and large glaciers, is the largest reserve of water in the form of ice and snow outside the polar regions. The consequences of increased glacial melt can thus have serious implications for the hydrology of associated river systems. This changing pattern of water and glaciers will, in turn, have a long-term impact on vegetation and can affect the ecosystems of deciduous and temperate forests.
Another major peril of fast-melting glaciers is the formation of lakes that can trigger floods. Such phenomena known as glacial lakes outburst floods (GLOF) have already occurred in parts of Nepal.
Glaciologists say what is crucial is a comprehensive science-based study of the Himalayas cutting across national boundaries. Such an exercise would yield a true picture of the drivers of climate change and provide answers on how to deal with the pollutants.