This article incorrectly said that the extent of Arctic sea ice is now 2 million square miles below the long-term average for Aug. 26. It is 2 million square kilometers below the long-term average for Aug. 26.
Scientists Report Further Shrinking of Arctic Ice
Wednesday, August 27, 2008
Arctic sea ice has shrunk to the second-lowest level since record-keeping began three decades ago, a group of international researchers determined yesterday, a revelation underscoring how rapidly climate change is transforming ecosystems in northern latitudes.
The extent of Arctic sea ice is now 2 million square miles below the long-term average for Aug. 26, according to the International Arctic Research Center and the Japanese Aerospace Exploration Agency, a figure that is within 400,000 square miles of the all-time record low set in September 2007. This figure is already below the long-term average for September ice cover and because the ice traditionally reaches its minimum level in mid-September, researchers warned that a new low might be recorded within weeks.
The National Snow and Ice Data Center (NSIDC), which independently analyzes Arctic ice cover, will announce today that it has reached the same conclusion, based on a five-day mean of satellite measurements.
"If we continue to lose ice at this rate, we will best" the 2007 record, said Julienne Stroeve, an research scientist. "We're going to lose that ice, so we've got to understand what this means for the rest of us."
According to the data center's recent reports, the ice over the Chukchi Sea is "already showing patches of open water within the ice. Much of the Beaufort Sea north of Alaska is open and the Laptev Sea and East Siberian Sea have opened extensively in the past 13 days."
The shrinking sea ice is increasing the pressure on polar bears in the region: A recent federal aerial survey found nine polar bears swimming in Alaska's Chukchi Sea, with one at least 60 miles from shore.
Margaret Williams, who directs the World Wildlife Fund's Alaska office and traveled to Barrow, Alaska, last week to assess how sea ice decline is affecting polar bears, said that while these animals have swum in open ocean in the past, they are now traveling much longer distances.
"It is very unusual to see so many bears in the open water at one time during a short flight period," Williams said, noting that government scientists spotted the bears over a six-hour period. "It's very worrisome. It's what we had anticipated, but it's happening right before our eyes."
By comparison, federal scientists spotted a total of 12 polar bears swimming in the open ocean between 1987 and 2003. The federal government conducts the aerial surveys not to assess the status of polar bears in the region, but to determine whether bowhead whales in the Arctic will be affected by offshore oil development there.
Even if researchers spot polar bears swimming in distress, they cannot rescue them, as attempts to tranquilize the bears would cause them to drown. In May, Interior Secretary Dirk Kempthorne listed polar bears as threatened under the Endangered Species Act, saying diminishing sea ice jeopardized their ability to survive in the foreseeable future, but he argued such a listing should not prompt the government to regulate greenhouse gases linked to global warming.
"We never get good news about the polar bears," said Melanie Duchin, a global warming campaigner for the advocacy group Greenpeace. "It's just yet another wake-up call in a long line of wake-up calls to politicians in this country that says, 'Hey, get your act together when it comes to global warming.' "
Researchers now estimate that summer sea ice in the Arctic is likely to disappear altogether by 2030, but Stroeve said the new satellite data suggest sea ice could vanish sooner than that.
Two weeks ago, the federal Climate Change Science Program released a "synthesis and assessment" report examining global warming in the Arctic and northern latitudes that suggests the region has already suffered ice loss of an "immense magnitude and unprecedented nature."
The report, which is open for public comment until Sept. 25, adds that the "current sea ice reduction . . . is progressing at a very fast rate that appears to have no analogs in the past" and that "sustained changes in sea-ice coverage may cause perhaps the largest temperature changes observed on the planet."
Stroeve said researchers anticipated this year's ice decline could rival last year's because so much of the Arctic's ice cover is one-year ice, which is thinner than ice that has built up over multiple years. This year, 73 percent of the Arctic Basin is composed of first-year ice, compared with 60 percent last year. In 1985, first-year ice made up 35 percent of the Arctic Basin.
"We knew we were vulnerable starting out, in terms of ice cover," she said.
Nick Sundt, the World Wildlife Fund's communications director for climate change, said the significance of this week's findings is not that a specific record is being set but that Artic sea ice cover is consistently declining.
"It's not what happens in an individual year, but what the trend is," Sundt said.