1. The Tundra Carbon Balance - some recent results with LPJ-GUESS contributions Paul Miller Ben Smith, Martin Sykes, Torben Christensen, Arnaud Heroult, Almut Arneth, Rita Wania, Dave McGuire

2. Background & Outline Why study the tundra? Relevant LPJ-GUESS developments Results from RECCAP (the present C balance) Results from CARBO-North (the present and future C balance) Funding and Support from: CARBO-North (EU-FP6) funded Mistra-SWECIA LUCCI MERGE

3. Tundra Boreal Forest Callaghan et al., Ambio, 2002

4. Why Study the Tundra? Substantial future climate warming is expected, with consequences for: Species diversity (which is less than temperate biomes - ACIA) Vegetation (growing season length, productivity etc.) Permafrost Soil carbon

5. Ongoing Warming And Amplification Serreze & Barry, 2011 Linear temperature trend, 1960-2009 Paleoclimatic Evidence for Arctic Amplification

6. More Productive Tundra Vegetation? Bhatt et al, 2010, Serreze & Barry, 2011

7. Carbon in NH Permafrost Tarnocai et al., GBC, 2009 Schuur et al. 2008 1672 GtC

8. Circumpolar & Tundra Soil Carbon Tarnocai et al., 2009

9. RECCAP – www.globalcarbonproject.org/reccap www.globalcarbonproject.org/reccap Objective: To “…establish the mean carbon balance and change over the period 1990- 2009” for all subcontinents and ocean basins 14 regions in the RECCAP synthesis: 10 terrestrial, 4 ocean regions Achieved by a sythesis of bottom-up (observations and modelling) and top-down (inverse) modeling approaches REgional Carbon Cycle Assessment and Processes Canadell et al., EOS, 2011

10. RECCAP Arctic Tundra Chapter Lead authors: Dave McGuire (Univ. Alaska), Torben Christensen (UL) Approach: Compare estimates of C exchange in Arctic tundra from observations, process-based modelling, and atmospheric inversions, 1990-2006 McGuire, Christensen et al., submitted

11. LPJ-GUESS Model Development Numerical soil temperature and soil water freezing calculations New shrub and open ground PFTs (Wolf) New peatland hydrology and PFTs Methane module Modelled vegetation, ALD, soil temperature & CO 2 /CH 4 fluxes agree satisfactorily with site and regional observations LPJ-GUESS WHyMe now available Wania et al., 2009,2011; Miller et al., almost submitted

12. LPJ-GUESS Simulations Climate forcing Tundra Gridcell LPJ-GUESS Upland Output (m -2 ): Vegetation CO 2 fluxes (NPP, NEE etc.) Carbon pools Peatland Output (m -2 ): Vegetation CO 2 fluxes (NPP, NEE etc.) Carbon pools CH 4 fluxes WHyMe Upland

13. RECCAP NEE & CH 4 Observations 250 estimates from 120 published studies From a CO 2 source in the 90s to a sink in the 2000s McGuire, Christensen et al., submitted Neutral! NEE CH 4

14. RECCAP Observations McGuire, Christensen et al., submitted

15. RECCAP Process-based Models LPJ-GUESS WHyMe, Orchidee, TEM6, TCF From a small CO 2 sink in the 90s to a greater sink in the 2000s 1990-99 2000-06 McGuire, Christensen et al., submitted

16. RECCAP Process-based Models - Seasonal Cycle - General agreement on seasonal cycle Summer NPP is higher in the 2000s 1990- 2006 2000-06 2000- 2009 McGuire, Christensen et al., submitted

17. RECCAP Process-based Models - Interannual Variability- GPP; NPP & Rh highly correlated NEP mostly uncorrelated McGuire, Christensen et al., submitted

18. RECCAP Process-based Models - Fire & CH 4 Interannual Variability- McGuire, Christensen et al., submitted

19. NEE From Inverse Models Similar shape of mean seasonal cycle Qualitative agreement with process models’ NEP McGuire, Christensen et al., submitted

20. Arctic Tundra C Balance McGuire, Christensen et al., submitted

21. The Future of the Tundra Carbon Balance?

22. CARBO-North Domain CARBO-North study region T. Virtanen et al. 2004

23. Climate Projections Mean Annual TemperatureAnnual Precipitation Warmer and wetter at all sites (A1B)

24. Seida – Tundra Bog Chamber and EC flux measurements of CO 2, CH 4 & N 2 O Photo: M. Repo

25. Seida – Tundra Fen Chamber and EC flux measurements of CO 2, CH 4 & N 2 O Photo: M. Repo

26. Abisko Birch Soil Temperature - Local Soil Properties - Data: M. Johansson

27. Wetland Hydrology Granberg et al. (1999) Mixed Mire Water and Heat Model (MMWH) – hydrology part only Soil column divided into acrotelm and catotelm Daily precip., snowmelt, evapotranspiration, run-off & run-on determine water profile Plants are never water stressed Can use empirical EVP too 10cm standing water allowed

28. Abisko (Torneträsk) Active Layer Data: M. Johansson & J. Åkerman

29. Modern Thaw Depths metre 1961-1990, LPJ-GUESS Tarnocai et al., GBC, 2009Miller et al., unpublished

30. Treeline kgC/m2 Tarnocai et al., GBC, 2009

31. Shrub & Open Ground PFTs Wolf et al. Clim. Ch. (2008)