Ice experts are shocked by this summer's meltdown in the Canadian Arctic, which reached yet another milestone as ice almost completely disappeared in polar regions that had previously not been seriously affected by global warming.
"The ice is no longer growing or getting old," says John Falkingham, chief forecaster for the Canadian Ice Service, the Environment Canada agency that helps ships find a way through the Northwest Passage and other parts of the Arctic.
"Ten years from now, we may look back on 2007 and say that this was the year we passed the tipping point."
An icebreaker encounters mostly open water in the Canadian Arctic.The tipping point is the term climatologists use to describe that moment in time when winter can no longer keep up with the meltdown that spring and summer brings. The less ice there is to reflect solar radiation back into the atmosphere, the warmer the Arctic Ocean becomes.
Until this summer, Falkingham, a 32-year veteran of the service, was reluctant to push the button as hard as other climate watchers, who have been saying that the Northwest Passage will be seasonally ice-free within 25 to 30 years.
But this summer, the ice retreated so far beyond all expectations that he was "shocked" if not "stunned" by what he and his colleagues saw.
Across the Arctic as a whole, the meltdown is where climatologists expected it would be in 2030. In Arctic Canada, 2007's total ice coverage was only a fraction below the minimum record set in 1998.
That wasn't a surprise to Falkingham because unlike the rest of the polar world, the islands in the archipelago protect the ice from the melting forces of winds, tides and storm surges.
What was surprising was the absence of ice in areas where it almost never melts.
The so-called "mortuary" of old ice that normally chokes M'Clintock Channel in the High Arctic was almost all gone. What's more, Viscount Melville Sound, "the birthplace" of a lot of Arctic ice, was down to half its normal summer cover.
"If there's very little ice in these two places, it raises questions about what's going to happen next year," Falkingham says.
Had John Franklin sailed the same route as he did back in 1845-46 when his two ships got stuck in ice, they would have had relatively clear sailing this year. All 129 men died on that expedition.
Queen's University scientist Scott Lamoureux and his colleagues got a glimpse of what all this warmth is doing to the Arctic landscape. The University of Alberta graduate was camped on the southern shores of Melville Island this past July.
It is the largest uninhabited island in the world and a place that is very likely to become a hub for future oil and gas developments in the Arctic.
Until this year, summers on the island had been left largely unaffected by the warming that has been taking place across the North. July temperatures have remained steady at about 5 C, partly because there is so much ice in the area.
But this year, Lamoureux and his associates basked in temperatures of 20 C or more. The heat was so intense that it melted the permafrost a metre below the surface.
Throughout those warm weeks of July, the scientists watched in amazement as the meltwater below lubricated the topsoil, causing it to slide down slopes, clearing everything in its path and thrusting up ridges at the valley bottom.
"The landscape piled up like a rug," says Lamoureux, an expert in hydro-climatic variability and landscape processes. "It was being torn to pieces, literally before our eyes. A major river was dammed by a slide along a 200-metre length of the channel. River flow will be changed for years, if not decades, to come.
"Had this happened in a populated or industrial area," he says, "the impact would have been catastrophic."
Falkingham says the rapid retreat of ice is now forcing the Canadian Ice Service to rethink its role in the future.
"A big part of our mandate is to help ships find a way through the ice. But if there is going to be so little ice in the future, it raises questions about what our role is going to be."
No comments:
Post a Comment