Arctic ice melting and not coming back: scientist
Andy Johnson, CTV.ca News Staff
Published Saturday, August 30, 2008 7:27AM EDT
Arctic sea ice is melting at an alarming rate, and some scientists have little hope the downward trend can be reversed before the ice disappears altogether.
The National Snow and Ice Data Centre in Colorado released its latest ice report this week, showing ice coverage in the region is at its second lowest level in 30 years.
"It's very different from in the past when you had a low year and you tended to rebound. We haven't been doing that anymore," Julienne Stroeve, a research scientist at the centre, told CTV.ca.
As of this week, 2008 is in second place for the lowest amount of sea ice since satellite measurements were first taken in 1979.
And with several weeks left in the melt season, 2008 could still surpass September 2007 for the lowest amount of sea ice since satellite measurements were first taken in 1979.
At last measure on Aug. 26, Arctic sea ice coverage was at 5.26 million square kilometers -- a decline of 2.06 million square kilometres from the beginning of August.
In September of last year, a record low was recorded, with 5.69 million square kilometres of sea ice recorded.
It's not a benchmark that Stroeve is proud of, but she's also not surprised by the chilling picture the numbers provide.
"I guess the main thing people should understand is this is just a continuation of that long term downward trend. I think whether or not we break the record it's just the continuation of what we've been seeing since 2002, where every year we're losing ice and we're not recovering at all," she said.
Much of the ice coverage in the Arctic normally melts each summer and reforms in winter. However, Stroeve said more and more of that ice is being lost to the sea, and failing to reform in winter.
The result is a sort of reverberating effect. Ice serves to reflect up to 80 per cent of the suns rays, and heat, back into space, helping keep the Arctic cool. But as the ice disappears, more and more of the sun's heat is absorbed in the ocean, then released to the air during fall cooling. That speeds up the warming process and makes the ice melt even faster.
Last year was a particularly bad year for sea ice in the Arctic, Stroeve said. Heavy storm conditions took a toll on ice off the coasts of Siberia and Alaska, unusually clear skies and warm ocean and atmospheric temperatures created a "perfect storm."
"You had a lot of things that happened together that caused a lot of ice loss," Stroeve said.
"But had that perfect storm happened say in the 1970s, you probably wouldn't have lost so much ice like you did last year. And the key thing seems to be the ice is just becoming really thin and it's that much more vulnerable to natural variability."
Other experts said the ice has reached a tipping point, and melt will be much more severe from here on in. Stroeve said she wouldn't characterize it as such, but said projection models have shown that with ice thinning at its current rate, it could all disappear -- in summer -- within a decade.
The most immediate effect of the ice loss, Stroeve said, is that animals that depend on the ice, such as polar bear and seals, are finding it harder and harder to survive as the winter ice shrinks, and takes longer to refreeze in the fall.
Observers from the U.S. federal government doing a whale survey in mid August reported seeing nine polar bears swimming off Alaska's northwest coast.
The bears were between 20 and 100 kilometres from shore. Some were swimming north, apparently trying to reach the polar ice shelf, which was more than 600 kilometres distant.
While polar bears have been known to swim 100 kilometres, but can often become dangerously weak from the ordeal.
Stroeve said she has also heard reports of seals being spotted further north than ever before as they travel further and further north to find ice.
"It's scary. It's such a huge change that's happening very quickly and it makes me very sad because I just can't see how the species that rely on the ice can survive this," Stroeve said.
While scientists have developed climate models to predict the future of ice in the Arctic, little is known about how those changing temperatures and conditions will play out in more southerly latitudes.
"That's the area I think science needs to go into next. We don't really know what this is all going to mean. We know everything is connected, so when you change one part everything is affected. But how exactly it's going to play out is still not very clear," Stroeve said.