Thicker, multi-year ice in much of the Arctic Ocean is being replaced by weaker first-year ice, scientists say. (PHOTO BY JANE GEORGE)
"The old, thick ice... is now beginning to melt out"
SPECIAL TO NUNATSIAQ NEWS
Arctic sea ice remains headed for another severe thaw this summer, tracking close to 2007’s record-setting retreat as some of the polar region’s oldest and thickest slabs — driven south into the warmer waters of the Beaufort Sea — are “beginning to melt out,” according to the latest report from the U.S. National Snow and Ice Data Center.
The Colorado-based institute, which bases its analysis on a 31-year satellite record of Arctic ice cover, said in its Aug. 4 report that this summer’s retreat is unlikely to surpass the unprecedented September 2007 meltdown to 4.13 million square kilometres — which alarmed scientists and governments around the world — but is trending toward another severe thaw expected to reach 5.0 million square kilometres or less.
“It would take a very unusual set of conditions in August to create a new record low,” the NSIDC stated in its report.
But echoing warnings issued recently by other U.S. and Canadian scientists that shrinking ice volume in the Arctic has become as much of a concern as declining ice area, the institute highlighted the ongoing replacement of thicker, multi-year ice in much of the Arctic Ocean by weaker first-year ice.
“Back in the 1970s and 1980s, old ice drifting into the Beaufort Sea would generally survive the summer melt season,” the centre stated. “However, the old, thick ice that moved into this region is now beginning to melt out, which could further deplete the Arctic’s remaining store of old, thick ice.”
There were also signs, however, that this year’s ice melt slowed in July compared with the rate of retreat recorded in May and June. Both of those months saw the ice melt faster than in any previous May or June since satellite measurements began in 1979.
But in July, the rate of retreat was closer to the annual average.
Still, this summer’s sea-ice minimum — expected to be reached around Sept. 15, before the annual winter re-growth begins — is on track to be one of the two or three smallest since 1979.
Reductions of sea ice have businesses and governments throughout the circumpolar world preparing for increased ship traffic and economic activity in Arctic waters.
But scientists are generally concerned about the relatively rapid melting in recent years because the Arctic ice is believed to be approaching a “tipping point” that could see ice-free summers in the region in the coming years, with significant impacts on Arctic wildlife and global climate systems.