Canada's oldest ice formation melting at alarming rate, scientists say

Canada's oldest ice, the Barnes Ice Cap, which covers close to 6,000 square kilometres of Baffin Island, is shrinking at a dramatically accelerating rate, says a U.S. research team. It reports the ice cap has recently been thinning at almost 10 times the rate it was 25 years ago. 

While not a big surprise - glaciers and ice fields throughout the Canadian Arctic are wasting away as the climate warms - researchers say the demise of the Barnes Ice Cap is particularly noteworthy. It is the last remnant of vast kilometers-thick Laurentide ice sheet that blanketed Canada during the last ice age. 

"The oldest ice we have in Canada is in the Barnes Ice Cap," says glaciologist Martin Sharp, of the University of Alberta, noting that some of the ice is "20,000 years plus." 

The Laurentide ice sheet basically retreated onto the ice mass that is now the Barnes Ice Cap," says Sharp. "It's the last bit that got left behind. And now it's on it's way out too. 

"This old ice is an archive of history, and once it's gone, it's gone," says Sharp. 

The Barnes ice cap is locked in winter's deep freeze this week with Arctic winds driving temperatures below the -40 Celsius. But the ice cap, like much of the Canadian Arctic, is being bathed with increasingly warm summer temperatures. 

It is estimated that global sea level will rise 0.2 metres (20 centimetres) if the world's glaciers and small ice caps melt, but researchers say much more work is needed to understand and forecast the impact of the accelerating melt down which could see most of the ice vanish this century. 

William Sneed and his colleagues at the University of Maine compared historical and current data on one of Barnes' three ice domes and found a clear link between the warming climate and the accelerating thinning. 

Between 1970 and 1984, the dome thinned 1.7 metres, or about 12 centimetres a year. Then there was a "dramatic increase" in the rate of thinning as summer temperatures rose. Over the last 22 years, the dome thinned close to 17 metres, they report in the current issue of the journal Geology. That is close to 76 centimetres a year, "seven times the thinning rate between 1970 and 1984." Between 2004 and 2006 the rate accelerated still further, to about a metre a year, they report. 

"If the projections for global warming over the next century become a reality, the future is bleak for these ice masses," they conclude. 
Sharp, who leads a Canadian team studying glaciers and ice fields in the high Arctic, says the finding are consistent with what is being seen father north. 

"We've lost a lot of small glaciers and ice caps since 1960 and now what we are seeing is the big ones are taking a beating," he says, noting that the Barnes Ice Cap is not only the oldest but one of the 10 largest ice fields remaining in the Canadian Arctic. 

Author:Margaret Munro
Source:Canada.com
Date:2008-1-11