After the polar ice caps, the Himalayas have the largest amount of glaciers. More than thirty thousand sq. km of the Himalayan region is covered by the glaciers that can provide around 8.6 million cubic meters of water every year. Rivers, including the Ganga, the Indus, the Brahmaputra, the Salween, the Mekong, the Yangtze and the Yellow river are fed by glaciers in the Himalayas. Millions of people rely on this annual water supply to survive. Over the past several decades global climate change has influenced the Himalayan mountain glaciers significantly, pushing tempertures close to melting conditions (Rai and Gurung 2005). Recently, the Himalayan glaciers have been in a status of retreat at an increasing rate which will eventually result in a water shortage for all Himalayan countries (e.g. China, India, Nepal, and Bhutan).
Glacial retreat in the Himalayas
According to World Wildlife Fund report, more than two-thirds of all Himalayan glaciers are retreating (Rai and Gurung 2005).
Glaciers in the Chinese Himalayas are retreating at an increasing rate, particularly in the past 50 years. Between 1950 and 1970, more than 320 glaciers, in a study by Rai and Gurung (2005), were retreating.After 1990, this number increased to nearly 600. That is almost 95% of the total number of studied glaciers which shows a more widespread trend of glacial retreat (Rai and Gurung 2005).
Almost all the glaciers in the region of Mount Everest have been retreating during the last century.An important source of freshwater into Tibet, the Rongbuk Glacier has been retreating 20 m annually (Rai and Gurung 2005).
In India, the Gangotri Glacier retreated around 30 m every year during the recent decade.Melt water from this glacier has been a significant source for the Ganges River (Rai and Gurung 2005).
About 70% of Himalayan glaciers are retreating rapidly and climate change has been reported as the major factor (Ageta and Kadota 1991).
Military activities between India and Pakistan has been blamed for much of the retreat of the Indian Siachen glaciers (Hasnain 2005).Since 1984, both countries have been placing huge amount of armies and permanent military personnel in the Siachen glacial region. In 2003, a ceasefire was declared by both sides along the International Border around Siachen, but how long the impacts of military activities will continue remains unknown (Ahmed 2007).
River discharge will increase in the short term, however, "in the long run, ... water supplies in those regions (Himalayas rivers) will be in peril" (Qin 2009).
Thousands of glacial lakes have been created in this region.Glacier Lakes Outburst Floods (GLOF) are occurring with higher frequency than previous decades (Rai and Gurung 2005). For example, according a report from a Tibetan local government, if thereâ€™s a GLOF at the Longbasaba and Pida lakes, 23 towns and more than 12 thousand people will be endangered (Xin et al. 2008).
Impacts to agriculture include soil loss due to soil erosion, landslides and floods, and temperature increase.
A decrease in surface albedo will accelerate the global climate change which will in turn increase the speed of glacial retreat.
According to the Intergovernmental Panel on Climate Change report (IPCC 2007), the glacial retreat in the Himalayan region is continuing at an increasing rate, and due to the projected climate change in the near future, a great number of existing glaciers
Ageta, Y. and T. Kadota. 1991. Predictions of changes of glacier mass balance in the Nepal Himalaya and Tibetan Plateau: a case study of air temperature increase for three glaciers. Annals of Glaciology, 16, 89-94.
Ahmed, A. 2007. Military activity leads to melting of Siachen glaciers. DAWN March 18, 2007.http://www.dawn.com/2007/03/18/nat7.htm (last accessed 17 November 2009)
Hasnain, S. I. 2005. The Times of India July 29, 2005. http://www.ias.ac.in/currsci/mar102009/646.pdf (last accessed 17 November 2009)
IPCC. 2007. Chapter 4 Observations: Changes in Snow, Ice and Frozen Ground. In Working Group I: The Phsical Science Basis. , eds. S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H. L. Miller, 996. Cambridge, United Kingdom and New York, NY, USA: Intergovernmental Panel on Climate Change.
Qin, D. 2009. Global warming benefits to Tibet: Chinese official. August 18, 2009.
Rai, S. C. and C. P. Gurung. 2005. An Overview of Glaciers, Glacier Retreat and Subsequent Impacts in Nepal, India and China. WWF Program. http://assets.panda.org/downloads/himalayaglaciersreport2005.pdf (last accessed 17 November 2009)
Xin, W., L. Shiyin, G. Wanqin and X. Junli. 2008. Assessment and Simulation of Glacier Lake Outburst Floods for Longbasaba and Pida Lakes, China. Mountain Research and Development, 28, 310-317.