Welcome to the final meltdown
New research: Summer sea ice will vanish in 10 years
Within 10 years, the Arctic Ocean may be ice-free all summer, according to an American researcher who says the ice is melting at a faster rate than all previous studies have estimated.
“If it melts at the rate it has been over the past five to 10 years, it will take 10 years to melt it all,” researcher Wieslaw Maslowski said in a telephone interview from the Naval Postgraduate School in California.
Maslowski was hesitant to acknowledge this “pretty extreme news,” which surfaced unattributed in other media, because the complete results of his research have yet to be published.
But Maslowski wants Arctic residents to understand that his 10-year timetable for an ice-free Northwest Passage in the summer is not a “prediction.”
“This is an understanding based on new model simulations suggesting that Arctic ice might be melting much faster in the recent past than anyone has believed,” he said. “Most of the climate and ocean circulation models probably significantly underestimate how quickly the ice is melting in the Arctic.”
Maslowski’s models show the Northwest Passage could be ice-free in summer before 2020, due to warm water flowing from the Pacific and Atlantic oceans into the Arctic Ocean. This influx of “significantly warmer water” appears to be melting the ice from below and accelerating the melt from other sources.
“If you look at where ice is melting, these are the areas where either Atlantic or Pacific waters enters or recirculates in the sub-Arctic,” he said.
Maslowski’s research on the “Causes of Changes in Arctic Sea Ice” was presented earlier this month at a seminar in Washington, D.C.
His presentation said a summer ice-free Arctic Ocean will “impose new requirements on the U.S. Navy, the Department of Defense, and Homeland Security,” and cause dramatic changes in the Arctic eco-system, including the extinction of polar bears.
“The above require understanding and prediction,” his presentation said.
According to this presentation, “oceanic forcing through Bering Strait” is partly responsible for the quickening loss of Arctic sea ice since 1979.
Arctic sea ice extent, that is, the area of ocean covered by at least 15 per cent ice, generally shrinks during the summer, and, in the past, grew in size, or recovered during the winter.
But this hasn’t happened in recent years.
Arctic summer sea ice cover in September 2005 was down 20 per cent, or by 1.4 million square km, from its summer average between 1979 to 2000. Over the last decade, September sea ice cover has decreased overall by 2.3 million square km.
At the same time, the extent of winter sea ice is also down: satellite measurements show the area covered by winter sea ice reached an all-time record low this March — down some 300,000 square km from last year.
Submarine data also shows multi-year ice was almost half as thick in the 1990s as it was in the 1950s to the 1970s. Although there isn’t a lot of recent data, the delay in the start of ice formation probably also means thinner ice.
Walt Meier, a scientist at the U.S. National Snow and Ice Data Centre, studies satellite images of sea ice extent in the Arctic.
“For many years there’s been this downward trend in the summer time, but it’s really accelerated over the past few years, and in the past four years, we’ve noticed a downward trend in the winter time,” Meier said in an interview from Boulder, Colorado.
The trend has been down for every year, he said, with each year lower than the year before. The results from 2005 “blew everything else away.”
“We’re getting more extreme melt in the summertime, and this is putting more heat into the ocean, and making the ocean warmer, which delays the onset of freeze-up… so it’s been lagging behind. It’s been forming at a later time,” Meier said.
In the past there was more variability: a low ice year would be followed by a high growth of ice and “so it would equal out.”
“These last four years have been one low year after another. It hasn’t really rebounded. It seems the ocean has gotten warmer, so it’s harder to freeze,” Meier said. “It can be hard to get out of the feedback.”
Other forces are also increasing melt: less ice means less reflection of the sun’s rays, so the ocean is absorbing more warmth.
Most models say this will lead to an ice-free Arctic in the summer by 2070-2100, and Meier said he’s somewhat skeptical about pushing back the timing back by 50 years, because he hasn’t seen all the data yet.
“But we have reason to believe that due to this positive feedback it may accelerate,” he said.