Falmouth, Mass. – As the climate warms, arctic permafrost — soil that has been frozen for thousands of years — is thawing; this releases carbon into the atmosphere and contributes to global warming. Because permafrost contains more carbon than either the atmosphere or tropical forests (another major carbon source), the release of permafrost carbon could greatly “amplify” climate change. And unlike fossil fuel emissions, there is no direct way to stop this process. Scientists have remained uncertain as to the timing and magnitude of these permafrost carbon emissions and the related effects on the climate system. A new paper published in Nature, co-authored by WHRC Assistant Scientist Susan Natali, suggests that thawing permafrost will result in a prolonged release of substantial quantities of greenhouse gases over the next several decades, and continuing for centuries. Carbon release from permafrost is no less dangerous because it occurs over time. In fact, during the rest of this century alone, enough carbon is expected to be released from thawing permafrost to make it much more difficult to limit global warming to 2 degrees Celsius, a widely-held goal.
The team of scientists synthesized recent research estimating how much carbon is stored in permafrost and the timing of greenhouse gas release from permafrost to the atmosphere. They conclude that carbon emissions from permafrost thaw will occur over the next several decades and continue through the century and beyond. According to co-author, Dr. Susan Natali, “The amount of carbon lost from permafrost this century are expected to be substantially greater than losses from land use change, and will make climate change happen faster than projected based on direct human activities alone. And importantly, this carbon source is not one that can be easily turned off as permafrost continues to thaw.”
Despite the massive impact permafrost thaw could have on the global climate system, permafrost carbon emissions or the climate feedbacks created from permafrost thaw were not included in the climate models analyzed in the recent Assessment Report 5 (AR5) of the Intergovernmental Panel on Climate Change (IPCC). This means that these models will tend to underestimate future climate change. Permafrost processes were not incorporated into these global climate models because of immature scientific understanding, including the challenge of sampling permafrost in remote regions and effectively simulating the different types of permafrost and the associated differences in vulnerability. The authors suggest that it is imperative to continue developing effective observation networks, including remote sensing capability, to adequately quantify real time carbon dioxide and methane emissions from permafrost regions.
Natali notes that “Accounting for biological carbon sources and taking action to reduce human emissions is critical because these direct human inputs will be increasingly coupled with greenhouse gas emissions from natural sources, such as permafrost.”
This research was made possible by a grant from the National Science Foundation Vulnerability of Permafrost Carbon Research Coordination Grant and Research, Synthesis, and Knowledge Transfer in a Changing Arctic: Science Support for the Study of Environmental Arctic Change.
WHRC is an independent research institute where scientists investigate the causes and effects of climate change to identify and implement opportunities for conservation, restoration and economic development around the globe.