A NASA-funded study suggests that carbon dioxide emissions from the winter in the Arctic can add more carbon to the atmosphere each year than is absorbed by Arctic vegetation, marking a sharp turnaround for a region that has captured and stored carbon for tens of thousands of years.
The study, published October 21, 2019, in Nature Climate Change warns that winter carbon dioxide loss from the world's permafrost regions may increase by 41% in the next century if human-caused greenhouse gas emissions continue at their current rate. Carbon emitted from thawing permafrost has not been included in most models used to predict future climates.
Permafrost is the richly frozen ground that covers 24% of the land in the Northern Hemisphere and encompasses large territories over Alaska, Canada, Siberia and Greenland. Permafrost has emitted more carbon than ever by humans via fossil fuel combustion, and this permafrost has kept carbon safely locked in an ice-cold embrace for tens of thousands of years. However, as global temperatures heat up, the permafrost thaws and releases greenhouse gases into the atmosphere.
"These findings suggest that carbon dioxide loss in winter may already offset the uptake of the plant's carbon uptake, and these losses will increase as the climate continues to warm," said Sa Woods Hole Research Center Arctic Program Director Sue Natali, lead author of the study. Studies focusing on individual sites have seen this transition, but so far we have not had a clear account of winter charcoal balance across the Arctic. "
This study is supported by NASA's Arctic-Boreal Vulnerability Experiment (ABoVE) and conducted in coordination with the Permafrost Carbon Network and more than 50 collaborative institutions. of the earth's changing environment, NASA sponsors scientific field campaigns for the t promote our understanding of how our climate is changing and can change in the future.
Researchers compiled observations on carbon dioxide emissions around the world in many places and combined these with remote analysis data and ecosystem models to assess current and future carbon dioxide losses during the winter for northern permafrost regions. They estimate an annual loss of 1.7 billion tonnes of coal from the permafrost region during the winter season of 2003 to 2017, compared to the estimated average of 1 billion tonnes of coal raised during the growing season.
To extend model forecasts for warmer conditions in 2100, the climate predicted for different scenarios of future fossil fuel emissions was used to calculate the effect on permafrost. If fossil fuel use is moderately reduced over the next century, carbon dioxide emissions in the winter would increase by 17% compared to current emissions. In a scenario where fossil fuel use continues to increase at the current rate through the middle of the century, winter carbon dioxide emissions from permafrost would increase by 41%.
"The warmer it gets, the more carbon dioxide will be released into the atmosphere from the permafrost region, which will contribute to additional warming," said co-author Brendan Rogers, climate scientist at Woods Hole Research Center. "It's about our study, which used many more observations than ever before, indicates a much stronger Arctic carbon source in winter. We may witness a transition from an annual Arctic carbon bench to a coal source, which is not good news. ”
Climate model groups around the world try to incorporate processes and dynamic events that affect the permafrost carbon dioxide emissions. For example, thermostatic lakes formed by melting ice can speed up the rate of carbon dioxide emissions by exposing deeper layers of permafrost to warmer temperatures. Similarly, arctic and boreal forest fires, which are becoming more common and more difficult, can remove the insulating top layer of soil, accelerate and deepen the permafrost.
"These interactions are still not reported in most models and will undoubtedly increase the estimates of carbon dioxide emissions from permafrost regions," Rogers said.
Reference: "Large Loss of CO 2 in Winter Observed over the Northern Permafrost Region" by Susan M. Natali, Jennifer D. Watts, Brendan M. Rogers, Stefano Potter, Sarah M. Ludwig, Anne-Katrin Selbmann, Patrick F. Sullivan, Benjamin W. Abbott, Kyle A. Arndt, Leah Birch, Mats P. Björkman, A. Anthony Bloom, Gerardo Celis, Torben R. Christensen, Casper T. Christiansen , Roisin Commane, Elisabeth J. Cooper, Patrick Crill, Claudia Czimczik, Sergey Davydov, Jinyang Du, Jocelyn E. Egan, Bo Elberling, Eugenie S. Euskirchen, Thomas Friborg, Hélène Genet, Mathias Göckede, Jordan P. Goodrich, Paul G rogan, Manuel Helbig, Elchin E. Jafarov, Julie D. Jastrow, Aram A.M. Kalhori, Yongwon Kim, John S. Kimball, Lars Kutzbach, Mark J. Lara, Klaus S. Larsen, Bang-Yong Lee, Zhihua Liu, Michael M Loranty, Magnus Lund, Massimo Lupascu, Nima Madani, Avni Malhotra, Roser Matamala, Jack McFarland, A. David McGuire, Anders Michelsen, Christina Minions, Walter C Oechel, David Olefeldt, Frans-Jan W. Parmentier, Norbert Pirk, Ben Poulter, William Quinton, Fereidoun Rezanezhad, David Risk, Torsten Sachs, Kevin Schaefer, Niels M. Schmidt, Edward AG Schuur, Philipp R. Semenchuk, Gaius Shaver , Oliver Sonnentag, Gregory Starr, Claire C. Treat, Mark P. Waldrop, Yihui Wang, Jeffrey Welker, Christian Wille, Xiaofeng Xu, Zhen Zhang, Qianlai Zhuang and Donatella Zona, October 21, 2019, Nature Climate Change .
DOI: 10.1038 / s41558-019-0592-8