Arne Winguth

University of Wisconsin-Madison, USA

Uwe Mikolajewicz, Matthias Gröger, Ernst Maier-Reimer,

Guy Schurgers, Miren VizcaínoMax-Planck-Institut für Meteorologie, Germany

The work is supported by the EU, BMBF-DEKLIM, UW Gradschool,

NASA CARBON CYCLE SCIENCE

CO2 Uptake of the biosphere:

Feedbacks between the carbon cycle and climate using

a dynamic earth system model

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MOTIVATION

• How will polar fresh water input by integrated

changes in surface circulation, continental ice sheets, and enhanced precipitation affect the thermohaline circulation on decadal-to-centennial time scales?

• How may these changes in the ocean circulation affect carbon uptake in the ocean and on land?

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Control simulation CO2 concentration increased from preindustrial (280 ppm) to 2 x, 3 x, or 4

x pre-industrial concentration with an increase of 1% per year 3x and 4x CO2 simulation where atmospheric radiation is calculated with a

pCO2 of 280 ppm (NO_FEED)

Simulations where freshwater input from ice sheet is not considered (NOICE)

Publication: Winguth et al., GRL, accepted.

Future Climate Change Simulations

Control2 x CO2

3 x CO2

4 x CO2

time (yr)

pC

O2(

pp

m)

ice sheet feedback

Noice sheet feedback

precipitation

ice sheets

pCO2 OCEAN-ATMOSPHERE DIFFERENCE 3 x CO2 - CONTROL

Mean900-1000

CUMULATIVE CO2 UPTAKE (kg C/m2)

Export Production mol C m-2 yr-1

PO4 anomaly mmol m-3

Central Pacific

3 x CO2-CONTROL

Vertical Velocity [10-6 m s-1]

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pH VALUE ANOMALY (3 x CO2- CTRL)

W. Atlantic

Riebesell Riebesell et al. et al. Nature (2001);Nature (2001);Engel et al.Engel et al.Limnol. Oceanogr. Limnol. Oceanogr. (2005)(2005)

Scanning electron micrographsunder conditions of 300 (top) and 780 - 850 ppm (bottom) pCO2 showing malformed coccospheres at the higher CO2 levels.

CO2 EMISSION SCENARIOS

1750-2000: fossil fuel emissions and land use data from CDIAC2000-2100: IPCC RES scenarios2100-3000: C2100 EXP(-1*(t-2100))

ANOMALY OF AIR SURFACE TEMPERATURE [K]

A1B B1

A2

Mean 2800-3000

ANOMALY OF AIR SURFACE TEMPERATURE [K]

MERIDIONAL OVERTURNING CIRCULATION [Sv]

precipitation

ice sheets

ANOMALY Of NET FRESHWATER INPUT [Sv]

NorthAtlantic

Change in Sealevel Equivalent [m]

Change in Sealevel Equivalent [m]

GREENLAND ANTARCTICA

Export Production Pg C yr-1

Change in carbon uptake

Conclusions In 1000-year future climate simulations

changes of freshwater input by ice sheets are significantly smaller than changes by precipitation.

Overall, consideration of both marine and terrestrial carbon cycle feedbacks with climate significantly affects the CO2 radiative forcing due to a total decrease in the carbon uptake by ~24-28%.

Climate-Carbon Cycle Feedbacks

OXYGEN (3 x CO2) [mol/L]mean 900-1000 Central Pacific