Near-surface permafrost areas could shrink by 16-24 percent
Global warming is likely to take a big bite out of Alaska’s permafrost the next few decades, U.S. Geological Survey researchers said after analyzing new satellite data.
The maps suggest 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. The Arctic warming trend is much greater than in mid-latitudes and is degrading 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 Virginia Burkett, USGS associate director for climate and land use change. “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 researchers also tried to project maximum thaw depth, which could help quantify how much methane and CO2 will be released to the atmosphere by melting permafrost.
In general, the results support concerns about permafrost carbon becoming available to decomposition and greenhouse gas emission.