Satellite mosiac of the Arctic Ocean in early
Sept. 2007, clearly showing the most direct
route of the Northwest Passage open (orange line)
and the Northeast passage only partially blocked (blue line).
The dark gray colour represents the ice-free areas, while
green represents areas with sea ice.
Credits: European Space Agency
The incredible retreat of the Arctic ice pack eroded further into record territory this past week, dissolving hundreds of miles of perennial floes into open water, and offering a satellite view of the most navigable Northwest Passage ever seen.
Still, the rate of decline slowed — only about 38,000 square miles melted away during the past seven days, an area larger than Indiana — suggesting the Perfect Melt may be close to hitting bottom for the season, according to the latest dispatch from the National Snow and Ice Data Center.
As of Sept. 16, the extent of ice covered about 1.63 million square miles — the smallest polar cap since satellite monitoring began in 1978. The area of the Arctic Ocean with at least 15 percent ice coverage was 22 percent smaller than than the previous all-time record minimum of 2.05 million square miles, set on Sept. 20-21 of 2005.
Vast areas of the Arctic are now known to be ice free for the first time in history.
The NSIDC reports in the latest fall update:
The main, deep channel of the Northwest Passage (Lancaster Sound to M’Clure Strait) has been open, or nearly ice-free, for about five weeks (since August 11, approximately).
Of note is the northernmost ice edge ever recorded, at 85.5 degrees North, near the 160 degrees east longitude line.
Sea ice is still declining, although the rate is very slow at present. Sea ice extent at this time of year can vary from day to day, as regions within the Arctic have small episodes of melt, freeze, or wind movement of the ice, just before the strong autumn cooling.
Arctic ice has been disappearing faster than anyone thought possible — eliminating habitat for marine mammals and undercutting the subsistence hunting life of Alaska Natives. Wiping out the home planet’s main air conditioner and leaving so much open water so late in the year will have unknown consequences for the global warming juggernaut. Have we reached the “tipping point” with runaway warming ahead?
Some climate models once predicted that Arctic ice might disappear during summer by the end of the century. But a new NOAA study compared models with observations and concluded the ice free Arctic could be about 30 years off. Other federal scientists reported that most polar bears — including all Alaska populations — would be gone by mid-century.
The retreat of the polar ice cap also poses heartbreaking problems for the people of Alaska villages like Shishmaref and Kivalina. With a fetch of open water stretching 1,000 miles or more, storms can build exceptionally big surf that consumes the barrier islands beneath village homes, tank farms, schools and roads. Lack of thick multi-year ice makes hunting less predictable and more dangerous.
Last week, an intense fall storm damaged the sea wall in Kivalina, and most villagers evacuated to other communities. People returned home over the weekend
But the season of fall storms has only just begun — and the protective ice that once protected barrier island villages from the year’s worst weather now floats hundreds of miles further north than it ever has before.
Satelite image of the McClure Strait in the
Canadian Arctic Archipelago on Aug. 31 2007.
The McClure Strait is part of the Northwest
Passage and has been fully open since early
August 2007.
Credits: ESA
The European Space Agency also commented on the record decline of ice in a story posted Friday, emphasizing the opening of the Northwest Passage to full navigation for the first time since satellite coverage began in 1978.
The total area covered by ice was about 1 million square kilometers less than the previous minimum record of 2005 and 2006, said Leif Toudal Pederson of the Danish National Space Center. Since, during the past 10 years, the ice area usually declined about 100,000 square kilometers from one season to the next, the sudden loss of 1 million square kilometers offers an extreme harbinger for future seasons.
“The strong reduction in just one year certainly raises flags that the ice (in summer) may disappear much sooner than expected and that we urgently need to understand better the processes involved,” Pederson said.
Note: The European Space Agency is tracking the “ice area,” whereas NSIDC is tracking “ice extent.” Area refers only to the ice itself: just the floes and bergs and pans and ridges. Extent includes the leads and open water between the ice. Typically, “ice extent” covers ocean with at least 15 percent ice cover.
Note once more: An AP story with a Paris dateline reported the ESA data but contained a grossly incorrect figure for the ice area as of Sept. 14, another one of those dunderhead mistakes so common in climate change stories by arithmetically challenged writers.
The story reported Pedersen as saying ice area has shrunk to about 1 million square miles — which was about 158,000 square miles below the actual measurement. This goof isn’t trivial. That much ice would cover the state of California.
Perhaps the AP writer confounded square kilometers with square miles, and then garbled Pedersen’s statement? Or maybe the writer simply rounded 3 million square kilometers (1.158 million square miles) down to the nearest million? Whatever the explanation, it’s one more argument for getting your information from original sources.