Sunday, March 16, 2008

Melting glaciers start countdown to climate chaos

Juliette Jowitt, in the Guardian (UK): For centuries, writers, painters and photographers have been drawn to the wild and seemingly indestructible beauty of glaciers. More practically, they are a vital part of the planet's system for collecting, storing and delivering the fresh water that billions of people depend on for washing, drinking, agriculture and power. Now these once indomitable monuments are disappearing. And as they retreat, glacial lakes will burst, debris and ice will fall in avalanches, rivers will flood and then dry up, and sea levels will rise even further, say the climate experts. Communities will be deprived of essential water, crops will be ruined and power stations which rely on river flows paralysed.

As a result, people will have to change their lifestyles, their farming, even move their homes, says Achim Steiner, executive director of the United Nations Environment Programme (UNEP). He also fears the problem could exacerbate tensions over inadequate supplies between neighbouring states and countries, possibly spilling over into conflict….

The scale of the problem so alarms Lester Brown, a leading environmental thinker, that he fears huge populations dependent on glacier-fed rivers in Asia - 360 million on the Ganges in India and 388 million on the Yangtze in China alone - will not be able to feed themselves, with devastating effect on already rising global food prices.

'These populations are larger than the populations of any other country in the world,' said Brown. 'We know from models there will be shifts in rainfall, crop yields reducing, but these are theoretical. Here there's a degree of certainty we've not seen before in terms of an historically negative effect on food security.'

Glaciers act like gigantic water towers: snow falls on the top in wet seasons, where it freezes and compacts over years, while melting water at the bottom is released gradually, keeping rivers flowing even in the hottest weather. 'Glaciers are like a bank,' says Professor Wilfried Haeberli, director of the World Glacier Monitoring Service. 'You have income - mainly snow - and you have expenditure - mainly melting: the difference between snowfall and melting is the yearly balance.'

….From 1850 to 1970, the team estimates net losses averaged about 30cm a year; between 1970 to 2000 they rose to 60-90cm a year; and since 2000 the average has been more than one metre a year. Last year the total net loss was the biggest ever, 1.3m, and only one glacier became larger. Worldwide, the vast majority of the planet's 160,000 glaciers are receding, 'at least' as much as this, says Haeberli, probably more - a claim supported by evidence from around the world….

The problem is perhaps most acute in Asia, where glaciers are an important source for nine major rivers which run through land occupied by 2.4 billion people. In Pakistan, for example, 80 per cent of agricultural land is irrigated by the Indus, which the WWF last year highlighted as one of the world's 10 big at-risk rivers because retreating glaciers provide 70-80 per cent of its flow…..

The glacier at McMurdo Sound, Antarctica, taken by Fred Walton, NOAA, Wikimedia Commons

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