Wednesday, 11 January 2012

Are Tibetan Glaciers Melting?

Recently, there has been a lot of debate about the effect of climate change on the Himalayan glaciers. Many reports suggest that the glaciers of the Himalaya are melting and even receding at an alarming rate, and if it continues, the rivers will initially cause flooding and later dry up, thus affecting millions of people in Asia. But, there are many who have challenged this argument and believe that situation isn’t as bad as the reports such as IPCC 2007 would make us believe.

A recent report launched during the 17th Conference of the Parties (COP17) in Durban (South Africa) by the International Centre for Integrated Mountain Development (ICIMOD) allegedly confirms the alarming problem of Himalayan glacial melting. This report follows an embarrassing and controversial report by Intergovernmental Panel on Climate Change (IPCC) in 2007 which claims that the region’s glaciers would be gone by 2035.

But sceptics dismiss such arguments of Himalayan glacier fear and blame it on the pool of misinformation based on erroneous report in the public arena. Richard Armstrong, a geographer at Colorado University’s National Snow and Ice Centre thinks, ''The mountains in and around the Himalayas are so high, unlike in the Andes, the Alps or the Rockies, that even in summer, temperatures remain below freezing point and most of the glaciers don’t melt away at all''.

Some sceptic went a step further and offered cash to climate change deniers. “We will pay $500 to anyone who submits a video of themselves attending the State Department event [the launch of UNDP-funded documentary titled ‘Revealed: Himalayan Meltdown’] and asking questions that aim to debunk the notion that global warming is causing the Himalayan glaciers to disappear,” announced Steven Milloy, climate change denier on the US-based website

In the Tibetan Plateau there are approximately 46,377 glaciers (catalogued by the Chinese Glacier Inventory in western China), storing huge reserves of freshwater. The Plateau holds the Hindu-Kush Himalayan Ice Sheet, considered the largest ice mass outside the two poles, therefore it is also known as the ‘Third Pole’.

Is the rising temperature on the Tibetan Plateau causing the melting and even retreat of glaciers in Tibet?

The Tibetan Plateau is warming about three times the global average, with temperature increases of 0.3°C or more per decade measured for the past half century. Consequently, there are indications that glaciers of the Tibetan Plateau are shrinking in all dimensions, mainly due to global warming coupled with black carbon from the neighbouring region.

A study by a group of Chinese researcher who have been conducting research on the waters, geology, glaciers, and wetlands in the headwaters of the Yangtze, Yellow and Lancang rivers in eastern Tibet (Qinghai Province) since 2005 found that a large area of the glaciers has melted in the 2,400-square-kilometer region. Cheng Haining, senior engineer with the provincial surveying and mapping bureau, said about 5.3 per cent, or 70 square kilometres, of the glaciers in Yangtze headwaters had melted away over the past three decades.

Similarly, according to a recent research by Duncan Quincey, a glacier researcher at Aberystwyth University (United Kingdom), eastern Himalayan glaciers are in an accelerating retreat, while only small numbers of western Himalayan glaciers are expanding, driven by different weather patterns in those areas.

The most recent case of glacial melting has been reported at Naimon’nyi glacier (or Gurla Mandhata) in south-western Tibet (Fig. 1), where half-century historical records, captured in ice cores from glaciers (glaciers can be dated by looking for traces of radioactivity buried in the ice), have vanished due to glacial melt and retreat. ‘’The glacier had melted so much that the exposed surface of the glacier dated to 1944’’ revealed professor Lonnie Thompson of Ohio State University (a team of researchers travelled to central Himalayas in 2006 to study the Naimona'nyi glacier, expecting to find some melting).

Fig. 1 Location of Naimon'nyi glaciers (Source: Bing Map)
Naimon’nyi is the highest peak of the Nalakankar Himal, a small subrange of the Himalaya (Fig. 2). It lies in Purang County of the Ngari Prefecture in the western Tibet, near the northwest corner of Nepal. According to Mary Davis, an ice-core researcher at Ohio State University, “At least the top 50 years of this record has been obliterated […] we surmise that perhaps it is gone because of melting." She believes that Naimon’nyi glacier is showing ominous signs of melt, including standing water in ponds on top of the glacier and small cylindrical melt-holes, called ‘cryoconites’, in the ice.

Fig. 2 View of the Naimon'nyi or Gurla Mandata mountain over the Barkha plain (Purang, Ngari region of Tibet).
A major problem associated with the melting of glaciers, in addition to its impact on river hydrology, is the formation of glacial lakes, which might burst to cause glacial lake outburst floods in the valleys below. According to a report by ICIMOD, there are 8790 glacial lakes within a selected area of Hindu-Kush Himalayas and more than 200 are identified as potentially dangerous.

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