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The shrinking third pole

The shrinking third pole
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First Published: Sun, Dec 06 2009. 09 54 PM IST

Photo: Gemunu Amarasinghe/AP
Photo: Gemunu Amarasinghe/AP
Updated: Sun, Dec 06 2009. 09 54 PM IST
Last month, one bullet point in a 64-page document caused unnecessary confusion as to the certainty of climate change impacts in India. The ministry of environment and forests unveiled a white paper on the state of the Himalayan glaciers. While the white paper itself contained a substantial discourse on the current scientific understanding about the health of these glaciers, and of the uncertainties in attributing any change in the size of the glaciers to climate change, the main bullet point covered by the media is that global warming and glacier retreat cannot be decisively linked. Highlighting this one point promotes scepticism about whether climate change is going to impact the Himalayan ecosystem, and it clouds public understanding of the importance of Himalayan glaciers in the global ecosystem. More importantly, it shelves any discussion of the need to set in place processes and agencies to monitor these glaciers with more rigour, in order for reliable forecasts of future water resources to be made. If India wants to be able to plan for its future, no matter who will ultimately pay for the mitigation costs, it needs to apply even more resources today to understand the response of the Himalayan glaciers to regional warming.
The Himalayas have been referred to as the Third Pole, containing the largest remaining stores of frozen fresh water outside the polar regions. These glaciers supply the rivers that feed half the world’s population. They influence global sea level both directly in terms of water discharge and also by transferring sediment eroded from the mountains directly to the ocean and gradually filling in the coastal seas. They also play a vital role in storing fresh water that melts and is released into the major rivers during the dry summer months.
Photo: Gemunu Amarasinghe/AP
There has been much publicity lately on the rapid shrinkage of glaciers in Greenland and Alaska. This shrinkage has been linked to rising air and ocean temperatures that increase the amount of ice melted on the surface of the glaciers and along the snouts of these glaciers where they end directly in the ocean. Many of these glaciers have also accelerated noticeably in the past decade. If a glacier speeds up, it may shrink by thinning without showing any retreat of the glacier snout. These observations have the science community exploring the varied local responses of glaciers to climate and whether these glaciers may reach a tipping point when the ice sheets destabilize and disintegrate quickly. These non-linear responses are why we have been unable to pinpoint the timing of the disappearance of these ice masses precisely, resulting in much unsubstantiated arm-waving about the complete disappearance of ice in regions such as the Himalayas by 2020, 2035 or 2050.
All published scientific studies show that the Himalayan glaciers have shrunk in the past century. Much less is known about the local dynamics of these glaciers and how rising temperatures and any shifts in the seasons will affect them. Most of the glaciers in the Himalayas are much smaller than those in Greenland or Alaska—where a small change in climate will result in a much larger percentage change in glacier mass. Many of these glaciers are at much higher elevations, where solar radiation plays a larger role in melting, and hence where changes in cloudiness may be the main control on glacier health. Some are fed primarily by snow that falls at the highest elevations during the summer monsoon, while others grow when snowfall is greatest in the winter—and therefore changes in the timing of precipitation and whether it falls as rain or snow will affect glaciers differently. All of these complexities add to local uncertainty in predicting how and how fast these glaciers will respond to climate change. We know far less about the Himalayan ice masses than any other ice mass on earth, despite their influence on the three billion-plus people who live downstream from them.
The true measure of glacier health is not the position of the snout but whether the glacier is losing mass through thinning—and it is its mass that determines what the storage capacity of fresh water may be and how it will contribute to downstream water supply. The variation in glacier size, shape and debris cover across the mountain range also dictates that no one glacier will truly be representative of what is happening across the whole region. Instead, what is desperately needed is a concerted effort to measure change at a number of glaciers around the region, across political boundaries, where the data collected can be standardized and shared so that a full picture of the fate of the Himalayan glaciers can be understood by all the countries affected.
No matter how India decides to approach the Copenhagen summit, no matter who will ultimately pay for the impacts of climate change, it is critical that the country builds its capacity to forecast what will happen to its water resources in the coming decades. To do this requires a robust focus on both long-term field and satellite monitoring of the Himalayan glaciers and mountain weather. Only then will the scientific community be able to deliver with some certainty an accurate account of what is happening to these glaciers and how they are responding to regional warming. However, that information may come too late — the moment to act may be upon the country much sooner.
Michele Koppes is a glaciologist from the University of British Columbia in Vancouver, Canada. Comment at theirview@livemint.com
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First Published: Sun, Dec 06 2009. 09 54 PM IST