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

10

15

1 8 15

22

29

36

43

50

57

64

71

78

85

92

99

106

113

120

127

134

141

148

155

162

169

176

183

190

197

204

211

218

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

n-8

6

Ja

n-8

7

Ja

n-8

8

Ja

n-8

9

Ja

n-9

0

Ja

n-9

1

Ja

n-9

2

Ja

n-9

3

Ja

n-9

4

Ja

n-9

5

Ja

n-9

6

Ja

n-9

7

Ja

n-9

8

Ja

n-9

9

Ja

n-0

0

Ja

n-0

1

Ja

n-0

2

Date

So

il T

em

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

1964

1973

1982

1991

2000

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)