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Removal of Exogenous Materials from the Outer Portion of Frozen Cores to Investigate the Ancient Biological Communities Harbored Inside
Published on: July 3, 2016
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A simplified, data-constrained approach to estimate the permafrost carbon-climate feedback
C D Koven1, E A G Schuur2, C Schädel2
1Earth Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA cdkoven@lbl.gov.
Summary
Large-scale permafrost thaw releases significant carbon (C) into the atmosphere. Our model estimates substantial C losses and increased greenhouse gas forcing under future warming scenarios, highlighting the sensitivity of frozen soils.
Area of Science:
- Earth and Environmental Sciences
- Climate Science
- Biogeochemistry
Background:
- Permafrost soils store vast amounts of carbon, and their thawing due to climate warming poses a significant feedback risk to the global climate system.
- Understanding the magnitude and rate of carbon release from thawing permafrost is crucial for accurate climate projections.
Purpose of the Study:
- To develop and apply a simplified, data-constrained model to estimate carbon feedback from large-scale permafrost soil thawing.
- To quantify projected carbon losses and associated greenhouse gas forcing under different future warming scenarios.
Main Methods:
- Utilized a novel approach, the Permafrost Carbon Network Incubation-Panarctic Thermal scaling (PInc-PanTher) approach, combining soil carbon maps, incubation experiments, and soil thermal models.
- Assumed frozen carbon does not decompose, but thawed carbon follows temperature-dependent decomposition trajectories based on a three-pool model fitted to incubation data.
- Simulated soil temperatures using ecosystem model outputs under medium (RCP4.5) and high (RCP8.5) warming scenarios (2010-2100), with constant litterfall inputs.
Main Results:
- Projected permafrost soil carbon losses of 12.2-33.4 Pg C under RCP4.5 and 27.9-112.6 Pg C under RCP8.5.
- Estimated global sensitivity of frozen soil carbon to climate change (γ sensitivity) at -14 to -19 Pg C °C⁻¹ over 100 years.
- Projected increases in methane (CH4) emissions of 7% (RCP4.5) and 35% (RCP8.5), adding 10-18% to greenhouse gas forcing.
Conclusions:
- Thawing permafrost represents a significant positive feedback to climate change, with substantial carbon release expected under future warming.
- The simplified PInc-PanTher approach provides a data-constrained estimate of the large-scale permafrost carbon response, despite neglecting some complex processes.
- Findings underscore the urgent need to consider permafrost carbon dynamics in climate change mitigation and adaptation strategies.
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