Alaska News

Total volume of Arctic ice shrank to record low in 2010

The total volume of Arctic sea ice shrank last fall to the smallest amount ever observed during the age of satellites, according to a new study that used a ultra-sophisticated computer modeling program that incorporates ocean observations, submarine data, and space-age monitoring.

But that 2010 record -- discussed in a research paper still in press and reported around the world by a Reuter's dispatch from a Greenpeace icebreaker -- may be already threatened by this year's polar meltdown.

New estimates by the same team of scientists at the Polar Science Center of the University of Washington appear to show ice volume is now plunging faster than it did at the same time last year when the record was set.

As of July 31, the last time numbers were crunched and posted online, the volume of sea ice appeared to be about 2,135 cubic miles -- more than 50 percent lower than the average volume and 62 percent lower than the maximum volume of ice that covered the Arctic back in 1979, the scientists said here.

"Sea ice volume is an important climate indicator," the group explains here. "It depends on both ice thickness and extent and therefore more directly tied to climate forcing than extent alone. However, Arctic sea ice volume cannot currently be observed continuously. Observations from satellites, Navy submarines, moorings, and field measurements are all limited in space and time."

The melt season for Arctic sea ice climaxes each September or October, and many people closely track the satellite generated reports and analysis of sea ice extent by the National Snow and Ice Data Center.

But another way of gauging the health of sea ice focuses on trying to estimate the actual amount of ice out there -- both the footprint of the floes on the surface, plus the fabled seventh-eighths hidden underneath in the sea. It's an exceedingly difficult task.

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To be published in the Journal of Geophysical Research, "Uncertainty in Modeled Arctic Sea Ice Volume" is a highly technical discussion of how the scientists at the Polar Science Center calculate, monitor and reality check the ongoing volume of sea ice in the Arctic Ocean using their Pan-arctic Ice Ocean Modeling and Assimilation System. The system uses complicated climate models for ice, ocean and air along with observations to conjure an estimate of what's really happening on and below the surface to the Arctic floes in real time.

The trend lines of these "anomalies" in volume seem to be literally dropping off their scales for this time of year in both 2010 and 2011, according to the most current chart. This year has dropped further.

"Given all the uncertainties and margins for error, it's tough to declare a single year a "record," said lead author Axel Schweiger and four co-authors in their paper. "However, the 2010 September ice volume anomaly did in fact exceed the previous 2007 minimum by a large enough margin to declare it a new record."

With a cinematic dateline of "500 MILES FROM THE NORTH POLE," news of their conclusion was posted around the world this week after a Reuters reporter filed a story from the Greenpeace ship Arctic Sunrise as it steamed through Far North waters. (Check out the Arctic Sunrise webcam.)

"The research adds to a picture of rapid climate change at the top of the world that could see the Arctic Ocean ice-free within decades, spurring new oil exploration opportunities but possibly also disrupted weather patterns far afield and a faster rise in sea levels," wrote reporter Gerard Wynn.

"The real worrisome fact is downward trend over the last 32 years," Schweiger told Wynn in an email.

In a story filed last week (dateline: OFF SVALBARD), Wynn interviewed NSIDC director Mark Serreze and reported that the extent of Arctic Sea ice had already reached the third lowest level in the satellite record with several weeks left before the annual slush cup ends.

"We just dropped below 4.6 million square kilometres and that's what we had in 2010 (at the minimum)," Serreze told Wynn in this story. "We're continuing the overall pattern of loss, and there's still a couple of weeks to go in the melt season.

"Will we break the record in 2007? I don't think so but we're going to be close."

Contact Doug O'Harra at doug(at)alaskadispatch.com.

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