Detecting and Forecasting Permafrost Degradation in a Warming Climate

Abstract:

The timing and rate of permafrost degradation are two of the major factors in determining the increase of carbon emissions from thawing permafrost. These changes in permafrost vary both temporally and spatially and do not happen everywhere at the same time. A good example of this heterogeneity is provided by our permafrost data collection in Alaska. Most of the permafrost observatories in Alaska show substantial warming of permafrost since the 1980s. The magnitude of warming varies with location, but is typically between 0.5 and 2°C. However, this warming is not linear in time and not spatially uniform. A short warmer period in the early 1980s was followed by a relative cooling in the mid-1980s. From the late-1980s to the late-1990s, the permafrost and active layer temperatures were increasing. During the first half of the 2000s, permafrost temperatures were not changing significantly at almost all sites in Alaska, except for the sites in the Brooks Range and in its southern foothills were temperature was still increasing. Interesting dynamics in permafrost temperatures have been observed in Alaska since the mid-2000s until present. While permafrost warming resumed on the North Slope of Alaska with a rate of increase between 0.2 to 0.5°C per decade, permafrost temperatures in the Alaskan Interior began a slight cooling trend that has continued during the first half of the 2010s. Most of these changes can be explained by changes in air temperature and snow cover during the observational period. These observations confirm that the future changes in permafrost temperature, in natural undisturbed conditions, will closely follow the changes in climate and as such can be successfully predicted using numerical models forced by established climate change scenarios. In our presentation, we will provide the results from application of our permafrost change models and discuss what this means in terms of potential organic carbon release and its conversion to the greenhouse gases carbon dioxide and methane.