B027-09
Permafrost Carbon Emissions from a Warming Arctic: What are the Implications for International Climate Goals?
Permafrost Carbon Emissions from a Warming Arctic: What are the Implications for International Climate Goals?
Tuesday, 8 December 2020: 18:02
Virtual
Abstract:
Permafrost contains the largest vulnerable carbon pool on the planet, holding nearly twice the
amount of carbon as is currently in the atmosphere. As the Arctic permafrost region continues to
warm, this carbon pool is expected to become a significant source of emissions to the atmosphere.
Despite the potential for a strong positive feedback to future climate change, permafrost emissions
are rarely included in climate models, many of which will inform the Intergovernmental Panel on
Climate Change 6 th Assessment Report. Critically, when models do incorporate permafrost emissions,
thawing is simulated as a gradual top-down process—ignoring non-linear processes such as abrupt
thaw and fire-permafrost interactions, which may have a similar or greater impact on our remaining
carbon budgets. Therefore, there is an urgent need for a comprehensive assessment that links global
climate change scenarios to carbon emissions from gradual thaw, abrupt thaw, and fire, and to
assess the implications for carbon budgets that limit warming to the 1.5°C and 2°C temperature
goals as outlined in the Paris Climate Agreement. To address this need, we developed a simple but
robust modelling framework that builds upon the reduced complexity Earth System Model (OSCAR)
and gradual permafrost thaw emulator by incorporating abrupt permafrost thaw, fire-carbon
emissions, and fire-induced permafrost degradation. We found that the impact of permafrost thaw
and fire emissions on global emissions budgets depended not only on the ultimate temperature
target, but also on the pathway to these targets (i.e., the timing, as well as the magnitude, of
anthropogenic emissions), with early mitigation of anthropogenic emissions associated with a larger
remaining emissions budget. For the first time, we demonstrate the substantial emissions that may
be released from the combined effects of gradual and abrupt permafrost thaw, fire, and post-fire
thaw from the Arctic permafrost region, which will dramatically reduce the global emissions budgets
that limit warming to 1.5°C and 2°C. Our conclusions underscore the urgency of international efforts
to implement existing climate policy pledges and to accelerate ambition ahead of the next
Conference of the Parties to the UN Framework Convention on Climate Change in 2021.
amount of carbon as is currently in the atmosphere. As the Arctic permafrost region continues to
warm, this carbon pool is expected to become a significant source of emissions to the atmosphere.
Despite the potential for a strong positive feedback to future climate change, permafrost emissions
are rarely included in climate models, many of which will inform the Intergovernmental Panel on
Climate Change 6 th Assessment Report. Critically, when models do incorporate permafrost emissions,
thawing is simulated as a gradual top-down process—ignoring non-linear processes such as abrupt
thaw and fire-permafrost interactions, which may have a similar or greater impact on our remaining
carbon budgets. Therefore, there is an urgent need for a comprehensive assessment that links global
climate change scenarios to carbon emissions from gradual thaw, abrupt thaw, and fire, and to
assess the implications for carbon budgets that limit warming to the 1.5°C and 2°C temperature
goals as outlined in the Paris Climate Agreement. To address this need, we developed a simple but
robust modelling framework that builds upon the reduced complexity Earth System Model (OSCAR)
and gradual permafrost thaw emulator by incorporating abrupt permafrost thaw, fire-carbon
emissions, and fire-induced permafrost degradation. We found that the impact of permafrost thaw
and fire emissions on global emissions budgets depended not only on the ultimate temperature
target, but also on the pathway to these targets (i.e., the timing, as well as the magnitude, of
anthropogenic emissions), with early mitigation of anthropogenic emissions associated with a larger
remaining emissions budget. For the first time, we demonstrate the substantial emissions that may
be released from the combined effects of gradual and abrupt permafrost thaw, fire, and post-fire
thaw from the Arctic permafrost region, which will dramatically reduce the global emissions budgets
that limit warming to 1.5°C and 2°C. Our conclusions underscore the urgency of international efforts
to implement existing climate policy pledges and to accelerate ambition ahead of the next
Conference of the Parties to the UN Framework Convention on Climate Change in 2021.