Alaska permafrost thawing sooner than expected

Up to a quarter of the permafrost that lies just under the ground surface in Alaska could thaw by the end of the century, according to a new study.

Using statistically modeled maps drawn from satellite data and other sources, U.S. Geological Survey scientists have projected that the near-surface permafrost that presently underlies 38 percent of boreal and arctic Alaska would be reduced by 16 to 24 percent by the end of the 21st century under widely accepted climate scenarios. Permafrost declines are more likely in central Alaska than northern Alaska.

Northern latitude tundra and boreal forests are experiencing an accelerated warming trend that is greater than in other parts of the world. This warming trend degrades permafrost, defined as ground that stays below freezing for at least two consecutive years.

Some of the adverse impacts of melting permafrost are changing pathways of ground and surface water, interruptions of regional transportation, and the release to the atmosphere of previously stored carbon.

A warming climate is affecting the Arctic in the most complex ways, said researcher Virginia Burkett, adding that understanding the current distribution of permafrost and estimating where it is likely to disappear are key factors in predicting the future responses of northern ecosystems to climate change.

The research is published in Remote Sensing of Environment.