Post on 01-Feb-2016
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The Tundra Carbon Balance- some recent results withLPJ-GUESS contributions
Paul MillerBen Smith, Martin Sykes, Torben Christensen,
Arnaud Heroult, Almut Arneth, Rita Wania, Dave McGuire
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
TundraTundra
Boreal Forest
Callaghan et al., Ambio, 2002
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
Ongoing Warming And Amplification
Serreze & Barry, 2011
Linear temperature trend, 1960-2009 Paleoclimatic Evidence for ArcticAmplification
More Productive Tundra Vegetation?
Bhatt et al, 2010, Serreze & Barry, 2011
Carbon in NH Permafrost
Tarnocai et al., GBC, 2009Schuur et al. 2008
1672 GtC
Circumpolar & Tundra Soil Carbon
Tarnocai et al., 2009
• 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
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
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 & CO2/CH4 fluxes agree satisfactorily with site and regional observations
• LPJ-GUESS WHyMe now availableWania et al., 2009,2011; Miller et al., almost submitted
LPJ-GUESS Simulations
Climate forcing
Tundra Gridcell
LPJ-GUESS
UplandOutput (m-2):VegetationCO2 fluxes (NPP, NEE etc.)Carbon pools
Peatlan
d
PeatlandOutput (m-2):VegetationCO2 fluxes (NPP, NEE etc.)Carbon poolsCH4 fluxes
WHyMe
Upland
RECCAP NEE & CH4 Observations
• 250 estimates from 120 published studies
• From a CO2 source in the 90s to a sink in the 2000s
McGuire, Christensen et al., submitted
Neutral!NEE
CH4
RECCAP Observations
McGuire, Christensen et al., submitted
RECCAP Process-based Models
• LPJ-GUESS WHyMe, Orchidee, TEM6, TCF
• From a small CO2 sink in the 90s to a greater sink in the 2000s
1990-99
2000-06
McGuire, Christensen et al., submitted
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
RECCAP Process-based Models- Interannual Variability-
• GPP; NPP & Rh highly correlated• NEP mostly uncorrelated
McGuire, Christensen et al., submitted
RECCAP Process-based Models- Fire & CH4 Interannual Variability-
McGuire, Christensen et al., submitted
NEE From Inverse Models
• Similar shape of mean seasonal cycle• Qualitative agreement with process models’
NEPMcGuire, Christensen et al., submitted
Arctic Tundra C Balance
McGuire, Christensen et al., submitted
The Future of the Tundra Carbon Balance?
CARBO-North Domain
CARBO-North study region
T. Virtanen et al. 2004
Climate Projections
Mean Annual Temperature Annual Precipitation
Warmer and wetter at all sites (A1B)
Seida – Tundra Bog
• Chamber and EC flux measurements of CO2, CH4 & N2O
Photo: M. Repo
Seida – Tundra Fen
• Chamber and EC flux measurements of CO2, CH4 & N2O
Photo: M. Repo
Abisko Birch Soil Temperature- Local Soil Properties -
-10
-5
0
5
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1 8 15
22
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Date
So
il T
em
p
OBS 20cm
IncThermCondOrgLayer 20cm
-6
-4
-2
0
2
4
6
8
10
12
Ja
n-8
5
Ja
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0
Ja
n-9
1
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Ja
n-0
0
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1
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Date
So
il T
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p
OBS 100cmIncThermCondOrgLayer 100cm
Data:M. Johansson
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
Abisko (Torneträsk) Active Layer
0
0.5
1
1.5
2
2.519
01
1910
1919
1928
1937
1946
1955
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1973
1982
1991
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2009
2018
2027
2036
2045
2054
2063
2072
2081
2090
2099
Year
ALD
[m]
Standard ALD
SnowDensityConstant
Observed ALD
Data:M. Johansson & J. Åkerman
Modern Thaw Depths
metre
1961-1990, LPJ-GUESS
Tarnocai et al., GBC, 2009Miller et al., unpublished
Treeline
kgC/m2
Tarnocai et al., GBC, 2009
Shrub & Open Ground PFTs
Wolf et al. Clim. Ch. (2008)