Sunday, January 03, 2016

North Slope Permafrost Melting Faster Than Expected

New projections of permafrost change in northern Alaska suggest far-reaching effects will come sooner than expected, scientists reported this week at the fall meeting of the American Geophysical Union.

"The temperature of permafrost is rapidly changing," said Vladimir Romanovsky, head of the Permafrost Laboratory at the University of Alaska Fairbanks Geophysical Institute.

"For the last 30 years, the mean annual ground temperature at the top of permafrost on the North Slope has been rising," Romanovsky said. The mean annual ground temperature -- an average of all of the years' highs and lows at the Deadhorse research site -- was 17.6 degrees Fahrenheit (minus 8 degrees Celsius) in 1988, and now it's 28.5 F (minus 2 C). Researchers expect the average annual ground temperature to reach 32 F (0 C), the melting point of ice, in many areas.

"We believe this will be before 2100 at many locations within the North Slope," Romanovsky said.

Romanovsky and his team, including UAF's Dmitry Nicolsky and Santosh Panda, entered data from several models, as well as their own on-the-ground observations, into the Geophysical Institute Permafrost Laboratory model, which primarily examines effects of climate and surface disturbances on permafrost.

They projected what would happen to permafrost in two possible scenarios.

A moderate scenario assumes worldwide carbon dioxide emissions will continue to decline at the modest rate they are now. This will lead to carbon dioxide levels in the Earth's atmosphere leveling off by roughly 2050 and staying constant until the end of the century.

"In this scenario we will see substantial thawing of permafrost on Alaska's North Slope, but only in certain areas, particularly the foothills north of the Brooks Range," Romanovsky said.

The extreme scenario assumes worldwide carbon dioxide emissions continue at today's rates. In that case, permafrost thawing on the North Slope will be much more significant and will extend beyond the foothills and into the Arctic coastal plain, Romanovsky said. In this outcome, the results at 2050 would be similar to the outcome in the moderate scenario, but after 2050 permafrost thawing would accelerate. More than half of the permafrost on the North Slope would be thawing by 2100 in this scenario.

"Under these conditions, the permafrost will become unstable beneath any infrastructure such as roads, pipelines and buildings," Romanovsky said. "The result will be dramatic effects on infrastructure and ecosystems."

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