A staggering 850 billion tons of carbon stored in Arctic permafrost, or frozen ground, could be released over the next century, according to a new study led by the U.S. Geological Survey. 44 billion tons of trapped nitrogen could also be unlocked as the region undergoes rapid melt.
For context, this is roughly the level of carbon already stored in the atmosphere today. The release of so much carbon and nitrogen from permafrost will exacerbate the global warming phenomenon and impact water systems both on land and offshore, according to the USGS and their collaborators. The previously unpublished nitrogen figure is useful for scientists making climate predictions with computer models, while the carbon estimate is consistent and gives credence to earlier scientific studies with similar measurements.
USGS Director Marcia McNutt: "This study quantifies the impact on Earth's two most important chemical cycles – carbon and nitrogen – from thawing of permafrost under future climate warming scenarios. While the permafrost of the polar latitudes may seem distant and disconnected from the daily activities of most of us, its potential to alter the planet’s habitability when destabilised is very real."
To generate the estimates, scientists studied how permafrost-affected soils, known as Gelisols, thaw under various climate scenarios. They found that not all Gelisols are alike: some have soil materials that are very peaty, with lots of decaying organic matter that burns easily. Others are very nutrient-rich. However, all Gelisols will contribute carbon and some methane as a result of decomposition when the permafrost thaws – and these greenhouse gases will add to global warming in the future. What was frozen for many thousands of years will enter our ecosystem and atmosphere as a new contributor.
Study lead Jennifer Harden, USGS Research Soil Scientist: "The scientific community researching this phenomena has made these international data available for the upcoming Intergovernmental Panel on Climate Change. As permafrost receives more attention, we are sharing our data and our insights to guide those models as they portray how the land, atmosphere and ocean interact."