This type of "positive feedback" is common in the Arctic, where global warming is also reinforced by the shift from sea ice (which reflects solar heat) to open water (which absorbs it), and by the release of methane, a potent greenhouse gas, through melting of permafrost.
Beary frigid fieldwork
Headquarters for Bronk's research is Barrow, Alaskathe northernmost and coldest city in the U.S.where extremely low wind chills and blizzard conditions are common. The average high temperature for January 25th, the day the VIMS team is scheduled to arrive for their 2011 winter field season, is -10F, with an average low of -22F. Winter water temperatures hover at -1.8C (28.7F).
The city's harsh climate, remote location, and resident wildlife make fieldwork for the VIMS team especially challenging. In winter, they reach their field sites by snowmobile, where they must drill though several feet of sea ice to take water samples.
During the "summer" field season (which coincides with September's sea-ice minimum) the team takes to small boats, clad in bulky "Mustang suits" to protect against the frigid waters.
An Inupiat native named Roxie helps guard against polar bears.But perhaps the most "chilling" aspect of their research, says Bronk, is dealing with polar bears, which requires that the field team be accompanied at all times by a local armed guide.
"They're a real threat," says Bronk, "the only bears known to stalk humans." She notes that each house in Barrow, population 3,982, features two doorsan outer and innerostensibly designed to keep out cold air. But this "air lock" serves another, equally important purposelocal residents always leave the outer door unlocked to provide a quick haven for themselves and neighbors in case a polar bear shows up in town.
|Contact: David Malmquist|
Virginia Institute of Marine Science