Wildfires offset the increasing but spatially heterogeneous Arctic–boreal CO2 uptake

• Published in: Nature climate change Vol. 15; no. 2; pp. 188 - 195
• Main Authors: Virkkala, Anna-Maria, Rogers, Brendan M., Watts, Jennifer D., Arndt, Kyle A., Potter, Stefano, Wargowsky, Isabel, Schuur, Edward A. G., See, Craig R., Mauritz, Marguerite, Boike, Julia, Bret-Harte, M. Syndonia, Burke, Eleanor J., Burrell, Arden, Chae, Namyi, Chatterjee, Abhishek, Chevallier, Frederic, Christensen, Torben R., Commane, Roisin, Dolman, Han, Edgar, Colin W., Elberling, Bo, Emmerton, Craig A., Euskirchen, Eugenie S., Feng, Liang, Göckede, Mathias, Grelle, Achim, Helbig, Manuel, Holl, David, Järveoja, Järvi, Karsanaev, Sergey V., Kobayashi, Hideki, Kutzbach, Lars, Liu, Junjie, Luijkx, Ingrid T., López-Blanco, Efrén, Lunneberg, Kyle, Mammarella, Ivan, Marushchak, Maija E., Mastepanov, Mikhail, Matsuura, Yojiro, Maximov, Trofim C., Merbold, Lutz, Meyer, Gesa, Nilsson, Mats B., Niwa, Yosuke, Oechel, Walter, Palmer, Paul I., Park, Sang-Jong, Parmentier, Frans-Jan W., Peichl, Matthias, Peters, Wouter, Petrov, Roman, Quinton, William, Rödenbeck, Christian, Sachs, Torsten, Schulze, Christopher, Sonnentag, Oliver, St. Louis, Vincent L., Tuittila, Eeva-Stiina, Ueyama, Masahito, Varlagin, Andrej, Zona, Donatella, Natali, Susan M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.02.2025
• Subjects: 631/158/2445; 704/106/125; 704/47; Climate Change; Climate Change/Climate Change Impacts; Earth and Environmental Science; Environment; Environmental Law/Policy/Ecojustice
• ISSN: 1758-678X; 1758-6798
• DOI: 10.1038/s41558-024-02234-5

The Arctic–Boreal Zone is rapidly warming, impacting its large soil carbon stocks. Here we use a new compilation of terrestrial ecosystem CO 2 fluxes, geospatial datasets and random forest models to show that although the Arctic–Boreal Zone was overall an increasing terrestrial CO 2 sink from 2001 to 2020 (mean ± standard deviation in net ecosystem exchange, −548 ± 140 Tg C yr −1 ; trend, −14 Tg C yr −1 ; P  < 0.001), more than 30% of the region was a net CO 2 source. Tundra regions may have already started to function on average as CO 2 sources, demonstrating a shift in carbon dynamics. When fire emissions are factored in, the increasing Arctic–Boreal Zone sink is no longer statistically significant (budget, −319 ± 140 Tg C yr −1 ; trend, −9 Tg C yr −1 ), and the permafrost region becomes CO 2 neutral (budget, −24 ± 123 Tg C yr −1 ; trend, −3 Tg C yr −1 ), underscoring the importance of fire in this region. How the carbon stocks of the Arctic–Boreal Zone change with warming is not well understood. Here the authors show that wildfires and large regional differences in net carbon fluxes offset the overall increasing CO 2 uptake.