For second straight year, melt may open Northwest Passage
ANCHORAGE, Alaska – Alaska’s warm weather this summer has all gone north. Way north.
Scientists at the National Snow and Ice Data Center say strong southerly winds from the North Slope have devoured a huge swath of Arctic ice larger than the state of Texas in the heart of the Beaufort Sea.
Combining that loss with the overall decline in sea ice in recent years should leave this year’s end-of-summer Arctic ice pack close to its lowest measurement on record. It may also open up the ice-encrusted Northwest Passage for the second year in a row – and only the second time in recorded history.
The Beaufort’s broad expanse of open water, which now extends more than a third of the way from Alaska to the North Pole, far surpasses the ice-free zone that prevailed there last summer when Arctic ice overall plummeted to a record low.
Daily satellite images relayed to the NSIDC headquarters in Boulder, Colo., also indicate the Northwest Passage is ice-free as far east of Alaska as Amundsen Gulf, about 600 miles east of the Alaska-Canada border.
All that remains to clear is a plug of ice that blocks the preferred northern sea route between Banks and Cornwallis islands, according to NSIDC senior research scientist Mark Serreze.
“But we’re seeing signs that the ice concentration is dropping there now,” Serreze said Thursday. “That plug could very well melt out in the next few weeks.”
Ice in the Arctic historically melts each summer until the middle of September. From 1996 to 2005, that summer minimum fell from a total of about 3 million to 2.1 million square miles of ice – a reduction roughly equal to about a third of the contiguous United States disappearing.
Comprehensive satellite monitoring of the Arctic has been available only since 1979, but the dramatic decline in the extent and thickness of the ice since then has prompted most climate scientists to conclude that “it’s clearly a global warming signal,” Serreze said.
Offsetting the ice loss north of Alaska this summer is a large accumulation of new first-year ice off the north coast of Russia. NSIDC forecasters say it’s hard to know whether it will melt or stay. If the latter occurs, Serreze said, then 2008 will probably go down as a close second to last year’s record Arctic ice minimum.
On July 31, the extent of sea ice in the Arctic stood at 2.98 million square miles – about 400,000 square miles less than the 1979 to 2000 average for the same date, according to data posted on the NSIDC Web site. But it was about 35,000 square miles more than the July 31 measurement during last year’s record summer.
“In other words, it’s not looking like it’s going to break last year’s record (minimum), but we’re well below normal,” Serreze said. “It should be No. 2.”
Norwegian explorer Roald Amundsen is credited as the first person to successfully navigate the passage, but it took him three years to do so – from 1903 to 1906 – and for most of the journey his boat was frozen solid.
Still up for grabs could be the distinction of first person to sail over a watery North Pole. Serreze thinks that opportunity might soon be nigh, at least for a few days each summer. Research shows that the ice across the Arctic is continuing to weaken.
High resolution imagery from NASA satellites coupled with altimeter systems are now able to determine how many inches the ice is floating above sea level. Allowing for the physical law that says almost nine-tenths of the ice is underwater, scientists can estimate its thickness, Serreze said.
The old multiyear ice this year is thinner than researchers expected, possibly because its underside is melting faster or because south-flowing currents are flushing some of the ice into the Atlantic, according to an analysis posted on the NSIDC Web site.
But the first-year ice is slightly thicker than expected, possibly because a lack of insulating snow cover last winter failed to protect it from the effect of deep freezing. In any event, the North Pole is still covered in ice.
“So Santa Claus is safe for this year,” Serreze said. “But he better start looking for some brand new real estate.”