October 21, 2019
Winter Carbon Emissions Shifting Northern Permafrost Region to a Carbon Source
Current and future winter losses of carbon dioxide from warming permafrost soils are likely to exceed regional plant uptake of carbon from the atmosphere.
The Science
A new synthesis of carbon dioxide flux observations in the northern permafrost region indicates that current carbon losses from soils to the atmosphere during the winter season (October through April) exceed average contemporary estimates of growing-season carbon uptake derived from process models. Extending model predictions to 2100, winter carbon losses from warming permafrost soils might increase by up to 41% under future climate change scenarios.
The Impact
A new synthesis of carbon dioxide flux observations in the northern permafrost region indicates that current carbon losses from soils to the atmosphere during the winter season (October through April) exceed average contemporary estimates of growing-season carbon uptake derived from process models. Extending model predictions to 2100, winter carbon losses from warming permafrost soils might increase by up to 41% under future climate change scenarios.
Summary
Permafrost region soils have captured and stored carbon for tens of thousands of years. However, the recent pace of warming in northern latitudes is accelerating the rate of decomposition of soil organic matter and the subsequent release of carbon dioxide (CO2) to the atmosphere. Yet, the amount of CO2 released during winter is highly uncertain and is not well represented by land models or by empirically based estimates. A large community of researchers synthesized regional in situ observations of CO2 flux from arctic and boreal soils to assess current and future winter carbon losses from the northern permafrost region. The researchers estimated present-day regional CO2 emissions during winter (October through April) to be 1.7 Pg C yr-1. This loss exceeds process model projections of contemporary regional carbon uptake by plants during the growing season (-1.0 Pg C yr-1). Extending model predictions to warmer conditions in 2100 indicates that winter CO2 emissions might increase 17% under a moderate mitigation scenario (RCP 4.5) but could rise 41% under a business-as-usual emissions scenario (RCP 8.5). Synthesis results provide a new baseline for winter CO2 emissions from northern terrestrial regions and suggest that enhanced release of soil carbon due to winter warming could offset growing season carbon uptake under future climatic conditions.
Principal Investigator
Susan Natali
Woods Hole Research Center
snatali@whrc.org
Program Manager
Daniel Stover
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
daniel.stover@science.doe.gov
Funding
This study was supported by funding from NASA’s Arctic-Boreal Vulnerability Experiment (ABoVE; grant no. NNX15AT81A to S.M.N.), with additional funding from NASA New Investigator Program (grant no. NNX17AF16G to J.D.W.), National Science Foundation (grant nos. 955713 and 1331083 to E.A.G.S.; no. 1503559 to E.E.J.), the Next-Generation Ecosystem Experiments–Arctic Project, U.S. Department of Energy (DOE) Office of Science to E.E.J., DOE Office of Science, Office of Biological and Environmental Research to J.D.J and R.M. (grant no. DE-AC02-06CH11357), National Research Foundation of Korea (grant nos. NRF-2016M1A5A1901769 and KOPRI-PN-19081 to B.-Y.L. and Y.K.), and funds that supported the data included in this synthesis.
Related Links
References
Natali, S. M., J. D. Watts, B. M. Rogers, and S. Potter, et al. "Large loss of CO2 in winter observed across the northern permafrost region." Nature Climate Change 9 852–857 (2019). https://doi.org/10.1038/s41558-019-0592-8.