by Lindsay McCord
Using a new approach to measure the extent of permafrost (permanently frozen soil), researchers have confirmed consistent widespread decline in stable permafrost that coincides with regional climate warming. This model provides greater resolution for looking at the condition of permafrost on a regional scale, and combined with other models, allows us to understand how permafrost is reacting to rising temperatures. Permafrost occupies roughly a quarter of land area in the Northern Hemisphere, over 40% of which is vulnerable to melting according to the new model. Twenty percent of permafrost land area is at a moderate risk, while 23% is facing severe degradation risk. In addition, the study found that permafrosts in boreal forests are more vulnerable than the more northern tundra permafrost. The model further confirms significant increasing regional trends of permafrost melting in the past 30 years in response to climate warming.
Permafrost soil contains high amounts of partially decomposed plant matter, and as it melts, microbes resume decomposing the organic material, releasing carbon dioxide and the more potent greenhouse gas, methane, into the atmosphere. Permafrost degradation also influences local and regional drainage and groundwater as well as destabilizes soil and enhances soil erosion.
The new model measures permafrost extent, which is the amount of permafrost that is completely frozen year-round, by using satellite microwave remote sensing data to extrapolate soil temperatures. The study used data from the 30-year period between 1980-2009 in order to compare the new method to existing models and regional sampling. Existing models provide relatively coarse resolution and regional sampling is impractical due to high costs. More detailed and cost-effective measurement of permafrost may facilitate more effective monitoring, allow for a greater understanding of how these soils react to warming, and inform predictions of how these biomes will react and interact to climate change.
Park, H., Kim, Y., & Kimball, J. S. (2016). Widespread permafrost vulnerability and soil active layer increases over the high northern latitudes inferred from satellite remote sensing and process model assessments. Remote Sensing of Environment, 175, 349-358.