Sea Ice Extent Far Below Previously Recorded Levels in Northern Route of Northwest Passage

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The Northwest Passage.  Source: NSIDC.
Source: NSIDC, 2010.

"[T]oday’s conditions in the Northwest Passage would likely astonish 19th century explorers," reports the National Snow and Ice Data Center in its latest (17 August 2010) sea ice update.  Overall, the center reports that as Arctic sea ice approaches its September minimum, sea ice extent is 649,000 square miles below average.

According the chart below from the Canadian Ice Service, sea ice in the northern route of the Northwest Passage not only has been well below the 1968-2000 average since early May, it has been much lower than in 2007 -- the year sea ice extent for the Arctic as a whole reached a record low.

Sea Ice Area in the Northern Route of the Northwest Passage.  Source: NSIDC Courtesy Canadian Ice Service.

In the graph above, the sea ice area for 2010 in the northern route of the Northwest Passage is shown in dark blue.  Source: NSIDC Courtesy Canadian Ice Service.

The NSIC explains:

"This year’s early clearing of sea ice [from the northern route of the Northwest passage] probably resulted from record warm temperatures this past spring over the Western Canadian Arctic, as well as the decline in older, multiyear ice in the channel over recent years. Spring 2010 was the warmest in the region since 1948: some regions of the Western Canadian Arctic were more than 6°C (11°F) above normal. These warm conditions helped break the ice up early in the northern route."

Sea Ice in McClure Strait along the Northern Route of the Northwest Passage, 17 August 2010.  Source: NASA.

 

Sea Ice in McClure Strait along the Northern Route of the Northwest Passage, 17 August 2010.  Source: NASA.



 The center continues:

"... [T]oday’s conditions in the Northwest Passage would likely astonish 19th century explorers such as McClure, Franklin, and Amundsen. In upcoming decades, the passage will be increasingly likely to open during summer.

Last month, Canadian investigators located the wreckage of the HMS Investigator, which sank on an expedition led by Captain Robert McClure in the 1850s. The McClure expedition had set out to rescue the Franklin Expedition, which had gone missing after leaving Baffin Bay for the Northwest Passage in 1845. McClure attempted to enter the passage from the west through what is now called M’Clure Strait, but quickly became trapped in the ice. They remained trapped through two winters before being rescued by another ship. The Franklin Expedition was not so fortunate: all 128 men perished. It was another fifty years before Norwegian Roald Amundsen and a small crew successfully navigated the passage. Their trek, by the southern route, took over two years."

In the figure below, the NSDIC shows the current sea ice extent in white relative to the median extent during 1979-2000 (orange line).  Note the large areas currently without ice that during the latter part of the 20th century had extensive sea ice.  These include a large area of the Chukchi sea (north of the Bering sea, left side of image), where walruses -- mostly females and their offspring -- normally congregate on the ice. 

Sea Ice Extent, 16 August 2010
Source: NSIDC.

In recent years, as the sea ice recedes away from the shore and into deeper waters, many walruses have been forced to leave the ice and congregate in massive "haulouts" along the Russian and Alaskan shorelines.  With such haulouts, females and young walruses are vulnerable to stampedes if something frightens the herd into the water.  Many may be killed, as occurred last year on Icy Cape in Alaska (see As Arctic Sea Ice Reaches Annual Minimum, Large Number of Walrus Corpses Found Along Alaska Shoreline, [18 Sept 2009] and  Dramatic Footage Shows Consequences for Walruses as Arctic Warms [1 Oct 2009]).

Walrus haul-out at Cape Schmidt, Russia, September 2009.  Source: WWF.

Walrus haul-out at Cape Schmidt, Russia, September 2009.  Source: WWF.

From mid-May until early July, the extent of Arctic sea ice was running below the record levels set in 2007.  But temperatures and winds in July slowed the decline in sea ice extent, resulting in levels that still are very low but now fall above 2007 levels. The NSIDC reports that there still is another month left in the melt season and winds have shifted in ways that are likely to reduce sea ice extent. It seems unlikely that the minimum in September will fall below 2007 levels, but it surely will be one of the lowest minimums on record.  That will be consistent with long term trends of declining arctic sea ice minimums as Arctic warming -- driven by rising atmospheric concentrations of greenhouse gases -- continues.

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