Approximately 1330-1580 Pg of soil carbon (C) are stored in soils of the northern circumpolar permafrost zone, almost twice as much C as currently contained in the atmosphere. Permafrost thaw, and C released via the microbial decomposition of previously frozen soil organic matter (SOM), is considered one of the most likely positive feedbacks from terrestrial ecosystems to the atmosphere in a warmer world. Yet, the rate and form of permafrost C release is highly uncertain but crucial for predicting the strength and timing of this carbon cycle feedback during this century and beyond. The Permafrost Carbon Network (PCN) is a synthesis project whose objectives are to link biological C cycle research with well-developed networks in the physical sciences focused on the thermal state of permafrost. Over the last five years, the network expanded from a core group of 40 scientists to more than 300 scientists from 121 research institutions located in 22 countries. It is structured into five working groups that focus on improving our understanding of 1) the size of permafrost C pools, 2) the decomposability of thawed permafrost SOM, 3) the fate of permafrost C from thermokarst and thermal erosion (abrupt thaw processes), 4) anaerobic and aerobic processes affecting CO2 and CH4 release, and 5) the capability to upscale and model the fate of permafrost C to develop more reliable projections of the role of permafrost C dynamics in the climate system. The working groups produce new knowledge by synthesizing data that can be assimilated by biospheric and climate models and that will contribute to future global environmental assessments, including the Intergovernmental Panel on Climate Change (IPCC). Since 2014 the Permafrost Carbon Network has become part of the Permafrost Action Team under the umbrella of the Study of Environmental Arctic Research (SEARCH) project, which is a system-scale, cross-disciplinary research program that seeks to connect the science of Arctic change to decisions makers.
Ted Schuur, Northern Arizona University, USA
A. David McGuire, University of Alaska Fairbanks, USA
Christina Schädel, Northern Arizona University, USA
In February of 2015, PCN worked with Dr. Gerhard Krinner of CliC to develop the CliC Permafrost Modeling Forum as a collaborative activity between CliC and the Permafrost Carbon Network. The strategy to improve the modeling of permafrost and carbon dynamics in the northern permafrost region involves three elements: (1) make the earth system modeling community more aware of deficiencies in the application of earth system models to the northern permafrost region, (2) develop benchmarking data sets that can effectively be used to segregated poor performing models from models that better represent conceptual and parameterization uncertainties, and (3) conduct coordinated model experiments that can be used to identify model deficiencies and improve parameterizations. The last activity forms the basis of the current Permafrost Carbon Model Intercomparison Project (PC-MIP) and has resulted in the first manuscript that is a retrospective analysis of carbon dynamics of the permafrost zone from 1960-2010 (McGuire et al. in prep). Together these steps represent attempts to improve interactions of the modeling community in the permafrost region with both the earth system modeling community outside the permafrost region and with the empirical community in the permafrost region.
In May of 2015, the 5th workshop for synthesis leads and co-leads of the Permafrost Carbon Network was held at Northern Arizona University in Flagstaff, Arizona. For this two-day workshop, CliC supported the participation of six researchers, all of them early career-scientists within 10 years of their final degree. The workshop included steering committee members and leading scientists of the Permafrost Carbon Network (a total of 25 participants). The workshop was attended by Dr. Kazuyuki Saito, the CliC representative of the Permafrost Modeling Forum, to discuss joint activities of CliC and Permafrost Carbon Network in implementing the steps of the Permafrost Modeling Forum. There was a particularly strong representation of early career scientists at this workshop and a number of new scientists engaged to take on the lead for a new synthesis. Identifying new leads for syntheses is a particularly crucial step for advancing syntheses. The following topics were identified during the workshop and will each be the topic for a breakout group discussion at the 5th Annual Meeting of the Permafrost Carbon Network on December 13th, 2015 in San Francisco, CA.
1) Methane syntheses: Lead: Dave McGuire, Jennifer Frederick, Chip Miller, David Olefeldt
2) Geospatial analyses: addressing the scaling components of PCN synthesis activities: Lead: Dan Hayes, Andrew Balser
3) Quantifying the influence of ecosystem structure on permafrost thermal dynamics: Lead: Mike Loranty
4) Where and when will the Arctic become wetter or drier? Lead: Cathy Wilson
5) Carbon emission from the arctic during the non-growing season: Lead: Sue Natali
6) Deep soil carbon pools: Lead: Jens Strauss, Guido Grosse, Gustaf Hugelius, Jen Harden
7) Dissolved organic matter composition in waters draining permafrost landscapes: Lead: Jon O’Donnell, Jorien Vonk
8) Greening versus browning of the Arctic: Lead: Christina Schädel
9) Synthesizing the use of carbon isotope (14C and 13C) approaches to understand rates and pathways for permafrost C mobilization and mineralization: Lead: Cristian Estop-Aragones, Ted Schuur
10) Primary and Derivative data products: Lead: Jen Harden, Claire Treat, Charlie Koven, Claire Treat, Umakant Mishra, Gustaf Hugelius
Many new publications came out of the efforts of the Permafrost Carbon Network in 2015. Of particular importance are Schuur et al. (2015) and Koven et al. (2015). Both publications are based on collective efforts and syntheses of many members of the Permafrost Carbon Network. More publications can be found on the PCN website.
The Permafrost Carbon Network will continue beyond 2016 as part of the Permafrost Action Team under the Umbrella of SEARCH. The next synthesis lead and co-lead workshop will be held in conjunction with the XI. International Conference on Permafrost (ICOP) in June of 2016 in Potsdam, Germany. This will also be an important opportunity to connect US-efforts with international colleagues. Scientific presentations for individual syntheses will be given during the sessions proposed at ICOP and the lead and co-lead workshop will be used to advance progress of individual syntheses by discussing progress and identifying cross-linkages between working groups and syntheses.