Research Highlights
Understanding the Controls on the Magnitude of the Permafrost Carbon–Climate Feedback
March 24, 2015
Objective
Quantify the carbon cycle dynamics of the permafrost region under a warming climate, and understand the roles of deep carbon lability and carbon–nitrogen interactions in determining the magnitude of the permafrost carbon–climate feedback.
Approach
Use CLM4.5-BGC, which allows for interactions between thawing permafrost, mineralization of carbon (C) and nitrogen (N) from decomposing permafrost soil and vegetation feedbacks, under a transient, offline, RCP 8.5 warming experiment to 2300. Identify N controls by comparing C–N and C-only versions of the model; and quantify role of deep C dynamics by varying a parameter that controls role of depth on decomposition.
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A) Change in total ecosystem C as a function of varied Zτ parameter as a consequence of adding decomposable deep C in the fully-forced C–N case. |
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B) Permafrost loss and soil C change for transient, fully-forced C–N run with decomposable deep C (Zτ = 10 m). The permafrost boundary retreats poleward with warming; C losses from soils follow and loss rates persist long after the period of rapid thaw. |
Results/Impacts
Permafrost soils are a potentially large component of the terrestrial carbon cycle response to warming, which are only recently available for understanding their dynamics in ESMs. Including these processes allows CLM4.5-BGC to predict the magnitude of the permafrost carbon–climate feedback, which is a potentially large fraction of global feedbacks on long timescales.
Koven, Charles D., David M. Lawrence, and William J. Riley. March 24, 2015. “Permafrost Carbon–Climate Feedback Is Sensitive to Deep Soil Carbon Decomposability but Not Deep Soil Nitrogen Dynamics.” Proc. Nat. Acad. Sci., 112(12):3752–3757. doi:10.1073/pnas.1415123112.
