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Climate change and glacial retreat

Vimal Khawas

Global warming and consequent changes in the climatic pattern across the geographies of the planet has been a hot topic in recent times across disciplines-natural and social sciences- supported by undue hype of popular media. Many scientists firmly believe global warming is hurting our environment. Even politicians and diplomats have become an integral part of the debate. Hence, global worming has acquired global significance and has found its place in the regional and global geo-politics. Secretary General of the United Nations, Kofi Annan emphasised at the 'Climate Change Conference in Nairobi' in November 2006 that climate change is not just an environmental problem, but also a health problem, a security problem and an economic problem for all nations . Today we have largely accepted that planet-wide environmental degradation is occurring and it is a serious concern for all of us. Since the mid-1970s the average air temperature measured at 49 stations of the Himalayan region rose by 1oC with high elevation sites warming the most (Hasnain 2000, WWF 2005). Studies in Nepal (Shrestha et al. 1999) and Tibetan Plateau (Liu et al. 2002) indicate the rising temperature in recent times, with the warming being consistent and continuous after the mid-1970s in Nepal. The average warming in Nepal in its annual temperature between 1977 and 1994 was found to be 0.06oC/yr. Incidentally, in both the countries the rate of warming is found to be more pronounced in the high altitude regions than the lower ones. Similarly, the lowland areas of India do not show significant warming trend (WWF 2005) indicating that the Himalaya is more sensitive and affected by climate change. Similar analysis (Shrestha et al. 2000) on precipitation data, however, does not reveal any significant trends in Nepal. One of the worst damages of global warming as revealed by various scientific studies has been the glacier retreat in the mountains and Glacial Lake outburst floods. While such phenomena have occurred due to geologic and geomorphic reasons in the past, scholars argue the rate and frequency of their occurrence have amplified severely in the last couple of decades, and sadly is increasing with time. Geoscientists have revealed a general shrinkage of mountain glaciers on a global scale and the trend was found to be more pronounced during the first half of the 20th century. After about 1950 mountain glaciers again started to grow. However, they again started to retreat with accelerating pace since the 1980s. Based on the scientific investigations, there have been forecasts that up to a quarter of the global mountain glacier mass could disappear by 2050 and up to half could be lost by 2100 (see WWF 2005). In the Himalayan region also glaciers have been found to be in a state of general retreat since 1850 (Mayewski and Jeschke 1979, WWF 2005). In Nepal, the Khumbu glacier, a popular climbing route to the summit of Mt. Everest, has retreated over 5 km from where Sir Edmund Hillary and Tenzing Norgay set out to conquer Mt. Everest in 1953 according to research findings. Similarly, several other Nepali glaciers are fast retreating in recent decades (see among others Fujita et al. 1998, 2001, Kadota et al. 1997, Seko et al. 1998, WWF 2005). In India situation is no better. Recent scientific studies show that almost all the major Indian Himalayan glaciers are retreating at an increasing pace (see WWF 2005). Of particular importance is Gangotri glacier as it has attracted a massive media attention in recent years. Latest data in this connection shows that Gangotri is retreating at the rate of 23 m/yr. According to the recent research findings, since the last inventory of glaciers and glacial lakes in Bhutan by the International Centre for Integrated Mountain Development (ICIMOD) in 2001, 120 additional glacial lakes have formed in the mountains (Kuensel 2006: December 03), indicating a rapid pace of glacier retreat in Bhutan Himalaya. It also reveals us the fact that glacier retreat or advance is either caused by natural factors or global environmental changes and that local ecology has little control over it. This is so because Bhutan's environment is relatively intact and the region still has over 64 per cent of its geographical area under forest. Glacial Lake outburst flood: Glacial Lake Outburst Flood (GLOF) is primarily an outcome of glacial melting. They are catastrophic discharges of water resulting primarily from melting glaciers. According to WWF (2005), many of the big glaciers have melted and retreated rapidly and have given birth to the origin of a large number of glacier lakes. Due to the faster rate of ice and snow melting, caused by the global warming, the accumulation of water in these lakes has been increasing rapidly and resulting sudden discharge of large volumes of water and debris and causing flooding in the downstream. An accelerated retreat of the glaciers in recent times has led to an enlargement of several glacial lakes. As the glaciers retreat they leave a large void behind. The ponds occupy the depression earlier occupied by glacier ice. These dams are structurally weak and unstable and undergo constant changes due to slope failures, slumping, etc. and run the risk of causing GLOFs. Characterised by sudden releases of huge amounts of lake water, which in turn would rush down along the stream channel downstream in the form of dangerous flood waves, GLOF waves comprise water mixed with morainic materials and cause devastation for downstream riparian communities, hydropower stations and other infrastructure. Further, Glacial lake outburst flood (GLOF) causes disasters to life and property along the downstream, results serious death tolls and destroy valuable forests, and farms. Some of the worlds largest documented historical GLOFs occurred in Karakoram-Himalaya. The damming of upper Shyok River by chongkumdan glacier formed a lake. A sudden outburst from this lake occurred in 1929 and th