Significant contribution to climate warming from the permafrost carbon feedback

Journal name:
Nature Geoscience
Volume:
5,
Pages:
719–721
Year published:
DOI:
doi:10.1038/ngeo1573
Received
Accepted
Published online

Permafrost soils contain an estimated 1,700Pg of carbon, almost twice the present atmospheric carbon pool1. As permafrost soils thaw owing to climate warming, respiration of organic matter within these soils will transfer carbon to the atmosphere, potentially leading to a positive feedback2. Models in which the carbon cycle is uncoupled from the atmosphere, together with one-dimensional models, suggest that permafrost soils could release 7–138Pg carbon by 2100 (refs 3, 4). Here, we use a coupled global climate model to quantify the magnitude of the warming generated by the feedback between permafrost carbon release and climate. According to our simulations, permafrost soils will release between 68 and 508Pg carbon by 2100. We show that the additional surface warming generated by the feedback between permafrost carbon and climate is independent of the pathway of anthropogenic emissions followed in the twenty-first century. We estimate that this feedback could result in an additional warming of 0.13–1.69°C by 2300. We further show that the upper bound for the strength of the feedback is reached under the less intensive emissions pathways. We suggest that permafrost carbon release could lead to significant warming, even under less intensive emissions trajectories.

At a glance

Figures

  1. Global average surface air temperature anomaly with respect to baseline runs with no carbon sequestered in permafrost soil layers.
    Figure 1: Global average surface air temperature anomaly with respect to baseline runs with no carbon sequestered in permafrost soil layers.

    Coloured areas are the likely surface air temperature (SAT) anomaly ranges for each DEP. The median for each DEP is superimposed as a black line. Note that the upper bounds for the two low-emission pathways (DEP 2.6 and 4.5) have the greatest surface air temperature anomaly (but not the greatest total warming).

  2. Changes in the size of each Earth system carbon pool in response to the addition of permafrost carbon to the UVic ESCM.
    Figure 2: Changes in the size of each Earth system carbon pool in response to the addition of permafrost carbon to the UVic ESCM.

    That is, the difference in the size of each carbon pool between simulations with and without permafrost carbon. All values are relative to the initial size of the frozen permafrost carbon pool (and a summation of all of the pools adds up to 100% for each year). Results are given for two emissions pathways (DEPs 4.5 and 8.5) and for three climate sensitivities to a doubling of CO2 (2.0, 3.0, and 4.5°C). Soil layers that thaw but are subsequently returned to a permafrost state continue to be administered by the active soil carbon pool, leading to the apparent high rate of transfer of carbon to the active soil carbon pool in the twentieth century.

  3. Evolution of atmospheric CO2 concentration in response to a cessation of anthropogenic CO2 and sulphate emissions in the year 2013.
    Figure 3: Evolution of atmospheric CO2 concentration in response to a cessation of anthropogenic CO2 and sulphate emissions in the year 2013.

    The dotted line represents the response for a climate sensitivity (to a doubling of CO2) of 2.0°C, the dashed line a climate sensitivity of 3.0°C and the solid line a climate sensitivity of 4.5°C.

References

  1. Tarnocai, C. et al. Soil organic carbon pools in the northern circumpolar permafrost region. Glob. Biogeochem. Cycles 23, GB2023 (2009).
  2. Schuur, E. A. G. et al. Vulnerability of permafrost carbon to climate change: Implications for the global carbon cycle. BioScience 58, 701714 (2008).
  3. Zhuang, Q. et al. Co2 and CH4 exchanges between land ecosystems and the atmosphere in northern high latitudes over the twenty first century. Geophys. Res. Lett. 33, L17403 (2006).
  4. Schaefer, K., Zhang, T, Bruhwiler, L. & Barrett, A. P. Amount and timing of permafrost carbon release in response to climate warming. Tellus 63B, 165180 (2011).
  5. Avis, C. A., Weaver, A. J. & Meissner, K. J. Reduction in areal extent of high-latitude wetlands in response to permafrost thaw. Nature Geosci. 4, 444448 (2011).
  6. Hegerl, G. C. et al. in Climate Change 2007: The Physical Science Basis (eds Solomon, S. et al.) (Cambridge Univ. Press, 2007).
  7. Moss, R. H. et al. The next generation of scenarios for climate change research and assessment. Nature 463, 747754 (2010).
  8. Koven, C. D. et al. Permafrost carbon–climate feedbacks accelerate global warming. Proc. Natl Acad. Sci. USA 108, 1476914774 (2011).
  9. Schneider von Deimling, T. et al. Estimating the near-surface permafrost-carbon feedback on global warming. Biogeosciences 9, 649665 (2012).
  10. Luke, C. M. & Cox, P. M. Soil carbon and climate change: from the Jenkinson effect to the compost–bomb instability. Eur. J. Soil Sci. 62, 512 (2011).
  11. Weaver, A. J. et al. The UVic Earth System Climate Model: Model description, climatology, and applications to past, present and future climates. Atmosphere–Ocean 39, 167 (2001).
  12. Schmittner, A., Oschlies, A., Matthews, H. D. & Galbraith, E. D. Future changes in climate, ocean circulation, ecosystems, and biogeochemical cycling simulated for a business-as-usual Co2 emission scenario until year 4000 AD. Glob. Biogeochem. Cycles 22, GB1013 (2008).
  13. Matthews, H. D., Weaver, A. J., Meissner, K. J., Gillett, N. P. & Eby, M. Natural and anthropogenic climate change: Incorporating historical land cover change, vegetation dynamics and the global carbon cycle. Clim. Dynam. 22, 461479 (2004).
  14. Zickfeld, K., Eby, M., Matthews, H. D. & Weaver, A. J. Setting cumulative emissions targets to reduce the risk of dangerous climate change. Proc. Natl Acad. Sci. USA 106, 1612916134 (2008).

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Author information

Affiliations

  1. School of Earth and Ocean Science, University of Victoria, 3800 Finnerty Road, Victoria, British Columbia V8W 3V6, Canada

    • Andrew H. MacDougall,
    • Christopher A. Avis &
    • Andrew J. Weaver

Contributions

A.H.M.D., A.J.W. and C.A.A. formulated the model experiments and wrote the paper. A.H.M.D. performed modifications to the ESCM, conducted experiments and analysed the results.

Competing financial interests

The authors declare no competing financial interests.

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