Story last updated at 12/30/2009 - 12:13 pm
In mid-December 2009, a few dozen Alaska scientists were part of the crowd that attended the fall meeting of the American Geophysical Union in San Francisco. I was there, too. I didn't make it to all 15,788 posters and presentations, but here are some highlights from the notebook:
The crumbling coast of northern Alaska "has experienced most of the (projected) 21st century warming already," said Bob Anderson of the University of Colorado at Boulder. During summer, the thawing northern coast is calving like a dirty glacier into the ocean. Northern Alaska is losing about 30 to 45 feet of land to the ocean each year between Point Barrow and Prudhoe Bay, the area Anderson studies. "The ultimate culprit is loss of sea ice," he said. When sea ice doesn't hug the shoreline, the ocean there gets warmer, waves are larger, and the frozen bluffs of ice-cemented soil have a longer time to thaw without sea ice buttressing them (the "landfast" ice that doesn't persist as long into summer as it did years ago).
When you hear of temperatures warming by a degree or two over some time period, you might wonder why such a small increment might be an indicator of a great change. Larry Hinzman, director of the International Arctic Research Center at the University of Alaska Fairbanks, put things in perspective for a roomful of his peers. "The Earth's an incredibly thermal-stable place," he said. "Its temperature has changed only 8 degrees Celsius in about the last half million years."
Warmer ocean temperatures probably triggered the dramatic retreat of Greenland's Jakobshavn Isbrae, the world's fastest flowing glacier, according to Roman Motyka of UAF's Geophysical Institute. He studied satellite photos of the glacier and measurements of ocean temperature near the location where the glacier flows into the sea. Motyka found the ocean warmed by more than 1 degree Celsius in the late 1990s, which led to the disintegration of the glacier's floating tongue. This may have led to Jakobshavn Isbrae's current race to the sea. Another researcher, Ian Howat of Ohio State University, also said that warm ocean temperatures at the face of Greenland glaciers are more responsible for making them race to the sea than rivers of meltwater flowing beneath glaciers. Melting where a glacier's tongue touches water is "like taking out a champagne cork," Howat said.
The ground is still moving in reaction to the Nov. 3, 2002 Denali Fault earthquake, a magnitude 7.9 that ripped a 200-mile frown across central Alaska. Jeff Freymueller of the Geophysical Institute reported that the ground is creeping faster on the south side of the fault, which cuts right though the Alaska Range. On the south side of the fault, the ground is creeping five times faster than it was before the earthquake. You can't feel the movement, which is just a few millimeters a year, but super-accurate GPS equipment can.
UAF graduate student Laura Brosius reported her studies of a scene playing itself out throughout northern Alaska, Siberia, and northern Canada. In small lakes she studies around Fairbanks, the frozen shorelines are thawing and dropping ancient vegetation into the water. Microbes are feasting on plant material that was flash frozen during colder times 15,000 to 30,000 years ago. The microscopic water creatures are converting the carbon in this former permafrost to methane. During winter, a person can see the methane as trapped bubbles in the lake ice. The amount of methane stored in the permafrost of these types of lakes in a certain area of Siberia is equal to 10 times the amount of the potent greenhouse gas currently wafting in the air, according to Katey Walter Anthony of UAF.
This column is provided as a public service by the Geophysical Institute, University of Alaska Fairbanks, in cooperation with the UAF research community. Ned Rozell is a science writer at the institute.