By definition, permafrost is ground that continuously remains below 0°C (32°F) for two or more years, located on land or under the ocean, however, much of the sub-surface ground in the Arctic polar regions has been frozen since the last ice age.
Close to 25 percent of the Northern Hemisphere is underlain by permafrost, including 85 percent of Alaska, Greenland, Canada, and Siberia. It can also be located on mountaintops, such as the Andes and exposed land in Antarctica in the Southern Hemisphere.
Permafrost is soil, rock, sediment, water, or ice mixed with the remains of carbon-based vegetation and animals that froze before they could decompose. According to the European Space Agency, scientists estimate that the world’s permafrost holds almost double the amount of carbon that is currently in the atmosphere.
Rate of permafrost thaw under global warming
Permafrost areas in the Northern Hemisphere have been warming since the 1980s, according to the Intergovernmental Panel on Climate Change’s latest report on oceans and cryosphere. And as permafrost warms and thaws, methane and carbon dioxide are released, adding these greenhouse gases to the atmosphere and making global warming even worse.
And there is a very good possibility that the total carbon released due to thawing permafrost each year may rival present-day emissions from all EU countries by the end of the century – and would amplify the impacts of global warming.
The speed and extent of permafrost thaw is an essential aspect in determining future mitigation efforts in dealing with climate change. This is why an ESA-funded research project was developed. Researchers relied on extensive long-term satellite data going back 21 years.
The data gave scientists a detailed record of annual changes in Northern Hemisphere permafrost soils from 1997—2018 and is the longest, concise satellite permafrost record currently available.
Details of the Arctic permafrost thaw
The CCI permafrost project research team, led by Annett Bartsch, the founder and managing director of b.geos, combines global satellite data products for land surface temperature and land cover with in situ measurements and the ERA5 climate reanalysis to generate a picture of the permafrost ground conditions.
The dataset is currently short of the three-decade minimum required to identify a climate signal, but the 21-year record shows interesting trends, according to Dr. Bartsch who points to rising ground temperatures, and greater variability along coastal areas and at high arctic latitudes.
“Average ground temperatures are rising at a rate of one degree Celsius per decade in the record,” explains Dr. Bartsch, adding that, “A larger temperature increase can be observed along the coasts of east Russia and northwest Canada bordering the Beaufort Sea Coast – where rates of coastal erosion are some of the highest in the world, and are, in part, exacerbated by permafrost thaw conditions.”
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Citing the unusually warm temperatures in the summer of 2020 in northern Russia, Professor Westermann, with the University of Oslo and the developer of the satellite-retrieval scheme, explains, “Although ground temperatures remained close to zero degrees, on-going slow seasonal ground ice melt and a deepening of the active layer can be observed in the data.”
The research-quality dataset is freely available from ESA’s Climate Change Initiative Open Data Portal along with a suite of research-quality global, satellite data sets for Essential Climate Variables.
