EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Cold truths: What does a warmer Arctic mean for carbon budgets consistent with the Paris Agreement?

Rachael Treharne1, Brendan Rogers1, Thomas Gasser2, Merritt Turetsky3, Erin MacDonald1, Carly Phillips4, and Sue Natali1
Rachael Treharne et al.
  • 1Woodwell Climate Research Center, Falmouth, United States of America
  • 2International Institute for Applied Systems Analysis, Laxenburg, Austria
  • 3Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, Colorado
  • 4Union of Concerned Scientists, Cambridge, United States of America

Arctic regions are warming more than twice as fast as the global average. This rapid warming is expected to drive a substantial net loss of carbon to the atmosphere, particularly from the thawing of ‘permafrost’, or perennially frozen ground. However, the majority of Earth System Models do not account for permafrost or processes driving the loss of permafrost carbon. In addition, where models do consider permafrost carbon feedbacks, thaw is typically simulated as a gradual, top-down process. This ignores critical, non-linear processes - notably abrupt permafrost thaw, wildfire, and fire-induced permafrost thaw. This means that the potential for a strong positive feedback to future climate change from permafrost regions is not well understood among policy decision-makers. There is therefore an urgent need for a comprehensive and policy-relevant assessment of permafrost carbon feedbacks and their implications for the temperature goals outlined in the Paris Climate Agreement. To address this need, we built upon a reduced complexity Earth System Model and gradual permafrost thaw emulator (Gasser et. al., 2018) by incorporating abrupt thaw, fire emissions, and fire-induced thaw. Using this framework, we assessed the implications of a comprehensive representation of permafrost feedbacks for carbon budgets that constrain warming to 1.5°C and 2°C. We found that combined feedbacks - gradual thaw, abrupt thaw, and fire processes - resulted in a substantial reduction in global carbon budgets to remain below 1.5°C and 2°C.

How to cite: Treharne, R., Rogers, B., Gasser, T., Turetsky, M., MacDonald, E., Phillips, C., and Natali, S.: Cold truths: What does a warmer Arctic mean for carbon budgets consistent with the Paris Agreement?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15535,, 2021.


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