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Vulnerability of Permafrost Carbon

Circumpolar Assessment of Organic Matter Decomposibility as a Control Over Potential Permafrost Carbon Loss Dr. Ted Schuur Department of Biology, University of Florida February, 2013.

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Vulnerability of Permafrost Carbon

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  1. Circumpolar Assessment of Organic Matter Decomposibility as a Control Over Potential Permafrost Carbon Loss Dr. Ted Schuur Department of Biology, University of Florida February, 2013 Co-Authors: Christina Schädel, RosvelBracho, Bo Elberling, Christian Knoblauch, AgnieszkaKotowska, Hanna Lee, YiqiLuo, Massimo Lupascu, Susan Natali, Gaius Shaver, Merritt Turetsky

  2. Vulnerability of Permafrost Carbon Research Coordination Network (RCN) http://www.biology.ufl.edu/permafrostcarbon/ PIs: Ted Schuur, A. David McGuire SteeringCommittee: Josep G. Canadell, Jennifer W. Harden, Peter Kuhry, Vladimir E. Romanovsky, Merritt R. Turetsky Postdoctoral Researcher: Christina Schädel Core funding: Additional Workshop funding: Workshop: May 2013; Annual Meeting @ AGU

  3. Permafrost Carbon Feedback to Climate What is the magnitude, timing, and form of the permafrost carbon release to the atmosphere in a warmer world? Cumulative C Emissions: 1850-2005 (2012) Fossil Fuel Emissions 365 Pg Land Use Change 151 Pg Permafrost Zone C Emissions: Future? 7-11% Loss? 120-195 Pg Expert Survey (Schuur 2013)(162-288 Pg CO2-Ceq)

  4. Working Group Activities Data syntheses in formats for biospheric or climate models 1) Permafrost Carbon Quantity Leads: GustafHugelius, C. Tarnocai, J. Harden Spatially distributed estimates of deep SOC storage; Quantifying uncertainties in circumpolar permafrost SOC storage 2) Permafrost Carbon Quality Leads: Christina Schädel, T. Schuur Incubation synthesis to determine pool sizes and decomposition rates; Network of long-term soil incubation experiments 3) Anaerobic/Aerobic Issues Leads: David Olefeldt, M. Turetsky Synthesis of CO2 and CH4 fluxes from northern lakes and wetlands; Controls on methane emission in permafrost environments 4) Thermokarst Leads: Guido Grosse, B. Sannell Metadata analysis of physical processes/rates; Analysis of thermokarst inventories; Distribution of thermokarst features in the Arctic 5) Modeling Integration & Upscaling Leads: Dave McGuire P. Canadell, D. Lawrence, Charles Koven, D. Hayes Evaluation of thermal and carbon dynamics of permafrost-carbon models; State-of-the-art assessment of the vulnerability of permafrost carbon and its effects on the climate system

  5. Permafrost Carbon Network Members Current number of: Members: 135+ Institutions: 70 Countries: 16 Working Groups Carbon Quantity: 28 members Carbon Quality: 27 members An/Aerobic: 27 members Thermokarst: 33 members Modeling Integration: 50 members

  6. Soil Organic Matter Decomposition Chemical recalcitrance (plant & microbial inputs plus transformation in soils) Physical Interactions (disconnection, sorption) Microbial communities (enzyme pathways) Environmental controls (pH, Temp, H2O, O2 , etc) Schmidt et al. 2011

  7. Permafrost Zone Incubation Database 40 incubation studies (34 published, 6 unpublished) ~500 unique soil samples long-term incubation synthesis

  8. Soil Incubation Synthesis • Lab incubations from • permafrost zone • (121 samples; • 8 studies) • Long-term incubations (1 year+) • Normalized • to5°C (Q10=2.5) • Upland boreal, tundrasoils • (Organic, surface <1m, deepsoils >1m)

  9. Carbon Decomposition Model Total respiration 3-pool model Cp= Ctot-(Cf+Cs) C-pool dynamics Cf Cs rf rs rp R Partitioning coefficient Schädel et al. 2013 Oecologia

  10. Partitioning Incubation CO2-C Flux total C-flux (measured) from passive C pool from slow C pool from fast C pool

  11. Turnover Time Fast C pool Slow C pool Passive C pool p<0.05 n.s. 500-10,000 Years Model Parameter Time in ‘incubation years’; continuous flux at 5 deg C

  12. Carbon Pool Sizes Fast C pool Slow C pool Passive C pool n.s. p<0.01 p<0.01

  13. Multiple regression table Data were transformed to meet assumption of normality

  14. Carbon Loss and C:N 1 year 10 year 50 year p<0.01 p<0.01 p<0.01 Time in ‘incubation years’; continuous flux at 5 deg C

  15. Carbon Loss and Vegetation Type 1 year 10 year 50 year n.s. p=0.018 p=0.04 Time in ‘incubation years’; continuous flux at 5 deg C

  16. Results Summary Vulnerability ranges from ~20% loss in organic soils to <5-10% for mineral soils [5 deg C; 10 incubation years] Vulnerability of boreal soils > tundra soils, but this difference diminishes over time Simple C:N and vegetation type metrics can be used to scale across landscapes and soil maps Full incubation dataset can determine sensitivity to changing environmental conditions

  17. Future Upscaling Carbon Quantity Working Group •  spatial extent • inventory 3m depth Hugelius et al. 2012 Modeling Working Group  Permafrost thaw trajectories with IPCC scenarios Harden et al. 2012

  18. Implications Carbon Pools x Thaw Trajectories x Incubation Rates = Potential Carbon Loss

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