UAF researchers to present at AGU press briefing

University of Alaska Fairbanks researchers Igor Semiletov and Donald "Skip" Walker will be among four panelists at a press briefing, The Arctic in Flux: New Insights from the International Polar Year, Tuesday, Dec. 16 at 9 a.m. Pacific Standard Time at the American Geophysical Union fall meeting at the Moscone Center in San Francisco. The briefing will present early results from a range of studies conducted during the International Polar Year, an international event focusing research efforts and public attention on the Earth's polar regions.

Semiletov will speak on recent discoveries of new methane seeps along the East Siberian Arctic Shelf. Semiletov is a research associate professor at the UAF International Arctic Research Center. Walker will speak on his Greening of the Arctic project, which has documented an increase in vegetation along the arctic coasts. Walker is a professor at the UAF Institute of Arctic Biology.

Other panelists include Julienne Stroeve of the University of Colorado, Boulder and Marco Tedesco of the City College of New York, New York.

Additional information on Walker and Semiletov's projects is attached.

CONTACT: Marmian Grimes, UAF public information officer, at 907-474-7902 or via e-mail at marmian.grimes@uaf.edu.

NOTE TO EDITORS: Reporters at the AGU meeting who need assistance contacting UAF researchers can contact Ned Rozell in the AGU Press Room or via e-mail at n.rozell@gi.alaska.edu.

Arctic greening linked to retreating sea ice

An interdisciplinary group of scientists led by Donald "Skip" Walker of the Institute of Arctic Biology at the University of Alaska Fairbanks has strongly linked sea ice changes to changes in Arctic land-surface temperatures and increased tundra greenness.

Walker will present results of his Greening of the Arctic study at the American Geophysical Union fall meeting in San Francisco on Dec. 16, 2008.

If the Arctic continues to warm as predicted, large changes in vegetation will have important consequences for the status of permafrost, depth of the thaw layer, snow patterns, hydrological cycles, wildlife and human uses of arctic landscapes. There will also be significant feedbacks to climate through changes in the carbon flux and in the amount of light and heat reflected by the land.

Walker's group combined information from Earth-orbiting satellites with ground-based studies and climate analyses to examine the trends of sea ice, land temperatures and vegetation using a simple numerical indicator of greenness called the Normalized Difference Vegetation Index. Vegetation reflects near-infrared light and absorbs visible light, Walker said: the greater the difference between the infrared and visible channels, the greater the density of green vegetation. The index also accounts for things like shadow and slope-aspect.

After examining 28 years of sea ice, land temperature and NDVI data, Walker's group found that between 1982 and 2007, summer sea-ice cover declined by 27 percent in a 50-kilometer band along Arctic Ocean coastlines. Corresponding changes in the greening index varied, ranging from a relatively large 24-percent increase along the Beaufort Sea in northern Alaska and Canada to a 12-percent decline along the Laptev Sea in Russia.

Walker's group is also measuring vegetation changes along an 1800-kilometer line, or transect, running from Alaska's North Slope to Ellef Ringnes Island in Canada and a 700-kilometer transect in Russia's Yamal Peninsula. Each crosses five different vegetative and climatic regions, called bioclimate subzones.

"If you have a natural climate gradient and you study it from cold to warm you have a good idea of what will happen when climate changes," Walker said. "We're using the transects as an analog for climate change."

Modelers have predicted that the Arctic Ocean could be ice-free in late summer by as early as the mid-21st century. "If this happens one of our major concerns is that entire ecosystems in the far north where there is currently perennial sea ice will vanish," said Walker.

The Greening of the Arctic project received funding from NASA and the National Science Foundation. It is part of UAF's work during the International Polar Year, an international event that is focusing research efforts and public attention on the Earth's polar regions.

Greening of the Arctic collaborators University of Alaska Fairbanks: Donald "Skip" Walker, Uma Bhatt, Vladimir Romanovsky, Martha Raynolds, Gary Kofinas, Patrick Kuss. University of Virginia: Howie Epstein, Qin Yu, Ben Cook, Domingo Alcaraz; NASA Goddard: Joey Comiso; Earth Cryosphere Institute, Moscow, Russia: Marina Liebman, Nataliya Moskalenko, Pavel Orekov, George Matyshak, Anatoly Gubarkov, Artem Khomutov. Arctic Centre, Rovaniemi, Finland: Bruce Forbes, Florian Stammler, Timo Kumpula, Elina Karlejaärvi. REC-TEA, Chinese Academy of Science: Gensu Jia. Swiss Federal Institute for Forest, Snow, and Landscape Research, Lausanne: Jed Kaplan, Hieke Lieschke.

CONTACT: Donald "Skip" Walker, professor, UAF Institute of Arctic Biology, at 907-474-2460 or ffdaw@uaf.edu. Marie Gilbert, IAB information officer, at 907-474-7412 or marie.gilbert@uaf.edu.

ON THE WEB: Greening of the Arctic IPY overview: http://www.geobotany.uaf.edu/goa/ Synthesis of Arctic System Science project, Greening of the Arctic http://www.geobotany.uaf.edu/sass/ Biocomplexity in the Environment project (North American transect): http://www.geobotany.uaf.edu/naat/ Arctic Geobotanical Atlas: http://www.arcticatlas.org/

Scientists find increased methane levels in Arctic Ocean

A team led by International Arctic Research Center scientist Igor Semiletov has found data to suggest that the carbon pool beneath the Arctic Ocean is leaking.

The results of more than 1,000 measurements of dissolved methane in the surface water from the East Siberian Arctic Shelf this summer as part of the International Siberian Shelf Study show an increased level of methane in the area. Geophysical measurements showed methane bubbles coming out of chimneys on the seafloor.

"The concentrations of the methane were the highest ever measured in the summertime in the Arctic Ocean," Semiletov said. "We have found methane bubble clouds above the gas-charged sediment and above the chimneys going through the sediment."

The new data indicates the underwater permafrost is thawing and therefore releasing methane. Permafrost can affect methane release in two ways. Both underwater and on land, it contains frozen organic material such as dead plants and animals. When permafrost thaws, that organic material decomposes, releasing gases like methane and carbon dioxide. In addition, methane, either in gas form or in ice-like methane hydrates, is trapped underneath the permafrost. When the permafrost thaws, the trapped methane can seep out through the thawed soil. Methane, a greenhouse gas 20 times more powerful than carbon dioxide, is thought to be an important factor in global climate change.

The East Siberian Arctic Shelf is a relatively shallow continental shelf that stretches more than 900 miles into the Arctic Ocean from Siberia. The area is a year-round source of methane to the globe's atmosphere. However, until recently, scientists believed that much of the area's carbon pool was safely insulated by underwater permafrost, which is, on average, 11 degrees Celcius warmer than surface permafrost.

Semiletov said this year's expeditions used both chemical and geophysical measurement techniques, a first in the area. He also noted that while the high-arctic ocean readings were surprisingly high, on par with those from high-arctic lakes, they are still much lower than is being found in subarctic regions.

"That means we cannot extrapolate the subarctic data to the entire Arctic," he said.

Semiletov, as associate research professor at IARC, leads the International Siberian Shelf Study, which has launched the multiple expeditions to the Arctic Ocean to collect data on methane release of the East Siberian Arctic Shelf. The ISSS includes 30 collaborating scientists from five countries. The project, which gained momentum during the International Polar Year, established more than 1,000 oceanographic stations in the Arctic and performed a few million measurements of methane mixing ratios of the Arctic atmosphere in the last five years. It is part of UAF's work during IPY, an international event that is focusing research efforts and public attention on the Earth's polar regions.

Semiletov is a chemical oceanographer who has studied carbon cycling in the arctic atmosphere-land-shelf system with emphasis on carbon dioxide and dissolved methane from both terrestrial and oceanic sources since the early 1990s. He joined the International Arctic Research Center in 2001. Since 2004, he has collaborated with IARC scientist Natalia Shakhova to develop the methane study at IARC.

International Siberian Shelf Study collaborators University of Alaska Fairbanks: Igor Semiletov, Natalia Shakhova, John Kelly, Vladimir Romanovsky, Gleb Panteleev, Sergei Marchenko, Dmitry Nicolsky, Alexander Kholodov; FEBRAS: Oleg Dudarev, Anatoly Salyuk, Irina Pipko, Viktor Karnaukh, Alexander Charkin, Denis Kosmach, Nina Bel'cheva, Svetlana Pugach, Nina Savelieva, Vladimir Iosoupov, Valentin Sergienko; Stockholm University: Orjan Gustafsson, Per Andersson, Jorien Vonk, Laura Sanchez-Garcia, Christoph Humborg, Vanja Alling; Gotheburg University: Leif Anderson, Goran Björk, Anders Olsson, Sara Jutterström, Sofia Hjalmarsson, Irene Wåhlström; Swedish Museum of Natural History: Per Andersson; Utrecht University: Celia Sapart, T. Roeckmanm; Institute of Atmospheric Physics RAS: Georgiu Golytsin, Irina Repina; Moscow State University: Nicolai Romanovskii, Vladimir Tumskoy; University of Manchester: Bart van Dongen; Luleå University of Technology: Johan Ingri, Fredrik Nordblad, Johan Gelting; Oxford University: Don Porcelli.

CONTACT: Igor Semiletov, associate research professor, at 907-474-6286 or via e-mail at igorsm@iarc.uaf.edu. Marmian Grimes, UAF public information officer, at 907-474-7902 or via e-mail at marmian.grimes@uaf.edu.

Source: University of Alaska Fairbanks