Scientists find increased methane levels in Arctic Ocean

Dec. 15, 2008

Fairbanks, Alaska—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 P!
orcelli.

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.

At the meeting of the American Geophysical Union in San Francisco December 14-19, the following press conference highlighted the International Siberian Shelf Study.

The Arctic in Flux: New Insights from the International Polar Year

SUMMARY: Continuing climate changes in the Arctic have received renewed scientific attention during the International Polar Year that began in early 2007. This briefing presents early results from a range of studies conducted during IPY based on climate models and new observations taken from sea, land, and space. Findings include the discovery of new seeps of the greenhouse gas methane along the East Siberian Arctic Shelf, a lengthening snowmelt season and a second year of ice mass loss in Greenland, and evidence that the predicted amplification of Arctic warming due to decreasing sea ice has already begun.

PANELISTS:

Igor Semiletov, Research Associate Professor, International Arctic Research Center, University Alaska Fairbanks, Fairbanks, Alaska USA

Julienne Stroeve, Research Scientist, National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colordado USA

Marco Tedesco, Director, Cryospheric Processes and Remote Sensing Laboratory; Dept. Earth and Atmospheric Sciences; City College of New York, New York, New York USA

D. A. (Skip) Walker, Greening of the Arctic Principal Investigator, Alaska Geobotany Center, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska USA

SESSIONS: C41B, U23F