Planet faces great glacier meltdown by 2100: Study
Monday, January 10, 2011
The Ottawa Citizen:
A fifth of the ice in the world's mountain glaciers and ice caps will disappear by 2100, with some regions losing as much as 75 per cent of their ice, according to an international study.
In the most detailed assessment yet of glaciers, which are often described as the world's water towers, the study found the European Alps, as well as New Zealand, could lose three quarters of their ice by the end of the century, while high mountainous regions in Asia may lose 10 per cent.
In Western Canada and the United States, 50 per cent of glacier ice could disappear by 2100, which could have substantial impacts on regional power dams and water supplies.
"For the long-term, it's not good for the economy because there will be a drop in river run-off and less water in reservoirs," says glaciologist Valentina Radic a professor at the University of British Columbia and the lead researcher.
Radic's study is not detailed enough to project regional affects, but she says other research underway should give a feel for the impact on Canadian water supplies, reservoirs and hydro dams.
Global warming's affect on glaciers is a poorly understood and controversial aspect of climate change. The United Nations Intergovernmental Panel on Climate Change, which shared the 2007 Nobel Peace Prize, has gone so far as to say Himalayan glaciers could melt away by 2035 — an prediction UN officials now admit was a big mistake. The meltdown of the Himalayan glaciers, they now say, is not going to be nearly as rapid or dire.
As part of efforts to get a better read on the planet's glaciers, Radic and her colleague Regine Hock at Uppsala University in Sweden assessed how the 2,638 ice caps and 120,229 mountain glaciers catalogued in the world glacier inventory will respond as the planet warms, using 10 state-of-the-art climate models. They then extrapolated the results to 19 regions of the planet that contain thousands more mountain glaciers and ice caps, which have yet to be included in the global inventory.
Radic says the most noticeable impact will be on glaciers less than five square kilometres in size, about half of which could melt away.
"Many small glaciers will actually disappear by the end of 21st century," she says. The European Alps, she says, could lose between 40 and 90 per cent of their small glaciers depending on the climate model used.
The study, published Sunday in Nature Geoscience, excluded the enormous ice sheets in Greenland and Antarctica in a bid to focus on the impact of atmospheric warming on the smaller glaciers and ice caps dotting the planet.
"Small glaciers do matter," says Radic, noting they are responsible for a substantial portion of sea level rise.
The study concludes that by 2100 the sea level will rise about 12 centimetres as a result of "wastage" from smaller glaciers, with Arctic Canada and Alaska making some of the biggest contributions.
The study estimates 21 per cent of the glacier ice will melt away by 2100, but Radic says it is a "low bound" figure because it does not include icebergs that calve off glaciers and tumble into the sea — a phenomenon that can account for 30 to 40 per cent of ice loss from glaciers that terminate at the sea.
While the study is the most detailed yet, she and other scientists stress the need to complete the global inventory of the glaciers, which currently only accounts for 40 per cent of the total.
"We still don't know exactly how many glaciers there are in the world," says Radic, noting the size and mass of many remote glaciers in North America are not known.
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