One-fourth of the permafrost underneath Alaska could thaw by the end of the century, according to U.S. Geological Survey scientists after using statistically modeled maps drawn from satellite data.
The survey projected that the near-surface permafrost that currently underlies 38% of boreal and arctic Alaska would be reduced by 16% to 24% by 2100. Permafrost declines are more likely in central Alaska than northern Alaska.
Northern latitude tundra and boreal forests are witnessing an accelerated warming, greater than in other parts of the world, a trend that degrades
permafrost, or the ground below it freezing for at least two consecutive years. The adverse impact of melting permafrost is changing pathways of ground and surface water, interruptions of regional transportation, and the release to the atmosphere of previously stored carbon.
Virginia Burkett, USGS Associate Director for Climate and Land Use Change, said: “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.”
Besides developing maps of near-surface permafrost distributions, the researchers developed maps of maximum thaw depth, or active-layer depth, and provided uncertainty estimates. Future climate scenarios produced by the Intergovernmental Panel on Climate Change (IPCC) also indicated similar permafrost distribution probabilities, anticipating varied levels of climate mitigation action by the global community.
These future projections did not take into account other possible future disturbances in the future, such as wildland fires, said USGS scientists. Otherwise, the results support concerns about permafrost carbon becoming available to decomposition and greenhouse gas emission. The research has been published in Remote Sensing of Environment.