By Margaret Munro | 16 May 2013
The Laurentide ice sheet once entombed Canada in two kilometres of ice, but all that is left is a blob of ice on Baffin Island now shrinking at a remarkable rate.
Scientists say the remnant of the once massive ice sheet is melting twice as fast as it was 50 years ago, which helps explain why Canada’s Arctic plays a lead role in stoking global sea level rise.
A new study says glaciers around the world are contributing almost as much to the rise of the world’s oceans as the Greenland and Antarctica ice sheets combined.
“And the largest contributor of all the regions is the Canadian Arctic,” says US glaciologist Alex Gardner, at Clark University, lead author the international study to be published Friday in the journal Science.
It says the glaciers are collectively losing almost as much ice each year as the Greenland and Antarctic Ice Sheets. Between 2003 and 2009, the researchers say the smaller glaciers poured approximately 260 billion tonnes of meltwater a year into the world’s oceans.
The largest contributions came from glaciers in Arctic Canada, followed by Alaska, coastal Greenland, the southern Andes and high-mountain Asia, says the study that tracked the contribution from 19 glaciated regions around the world.
There has been debate – and controversy – for years over how much glaciers are contributing to sea level rise. Particularly problematic were the estimates based on field measurements gathered by scientists who plant poles in glaciers and return yearly to gauge how much the ice has changed. Satellites, which have been able to “see” and measure the thickness of the world’s glaciers since 2003, indicated the glaciologists on the ground were overstating the shrinkage.
To sort out what is going on Gardner and leading ice scientists in Canada, the US and Europe pulled and reviewed the data for the 2003-2009 period to ensure they were comparing “apples with apples.”
It turns out that over the years scientists have tended to focus on smaller glaciers that are shrinking faster than glaciers in more inhospitable parts of the planet.