Figure: 2 Theglobalcarboncycle Sea-to-airfluxofCO for1995 Earthsystemmodels&futureclimate

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Earth system models & future climate

Figure: IPCC, 2001

Ulrike Lohmann (IACETH) Earth system models & future climate June 21, 2007 1 / 30

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Carbon cycle Observations Paleo Drivers Attribution Future Carbon&Future

The global carbon cycle

natural fluxes (black); anthropogenic ones (red)

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Carbon cycle Observations Paleo Drivers Attribution Future Carbon&Future

Sea-to-air flux of CO

for 1995

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Temperature & salinity in surface waters

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Carbon cycle Observations Paleo Drivers Attribution Future Carbon&Future

Nutrients in surface waters

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Carbon cycle Observations Paleo Drivers Attribution Future Carbon&Future

Ocean carbon pumps

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Ocean carbon pumps

The ocean can alter atmospheric CO2concentrations through 3 mechanisms:

I Solubility pump: absorption or release of CO₂ due to changes in solubility of gaseous CO2

I Organic carbon pump: changes in carbon fixation to POC in surface waters by photosynthesis and export of this carbon through sinking of organic particles out of the surface layer - this process is largely limited by availability of light and nutrients (P,N, silicic acid, iron)

I CaCO3counter pump: changes in the release of CO2in surface waters during formation of CaCO₃ shell material by plankton (is only important on very long timescales)

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Linear trend of annual T

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T , sea level &

NH snow cover

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11 of the 12 last yeares rank among the 12 warmest years since 1850

Ulrike Lohmann (IACETH) Earth system models & future climate June 21, 2007 10 / 30

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Carbon cycle Observations Paleo Drivers Attribution Future Carbon&Future

Global dimming in Central Europe

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Reconstructed temperatures

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Reconstructed climate 125,000 years ago

Ulrike Lohmann (IACETH) Earth system models & future climate June 21, 2007 13 / 30

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Carbon cycle Observations Paleo Drivers Attribution Future Carbon&Future

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Carbon cycle Observations Paleo Drivers Attribution Future Carbon&Future

Human vs. natural sources of GHGs

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Radiative forcing components

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Radiative forcing probability distribution

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Carbon cycle Observations Paleo Drivers Attribution Future Carbon&Future

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Observed vs. simulated T changes

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Carbon cycle Observations Paleo Drivers Attribution Future Carbon&Future

Predicted future temperature changes

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Predicted future temperature changes

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Predicted future temperature changes

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Predicted future precipitation changes

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Expected changes in extremes

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Changes in extremes

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Changes in extremes

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Carbon cycle Observations Paleo Drivers Attribution Future Carbon&Future

Current and projected CO

emissions

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1920 1940 1960 1980 2000 2020 2040 2060 2080 2100 0

500 1000 1500 2000

Inventories and Cumulative Fluxes [PgC]

1920 1940 1960 1980 2000 2020 2040 2060 2080 2100 0

500 1000 1500 2000

Inventories and Cumulative Fluxes [PgC]

HADLEY MODEL: IS92a SCENARIO

Emissions

IPSL MODEL: SRES-A2 SCENARIO

Emissions

CARBON-CYCLE /

CLIMATE SYSTEM FEEDBACKS

Atmosphere

Atmosphere Ocean

Ocean

Land Land

Sarmiento and Gruber (2002)

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Carbon cycle Observations Paleo Drivers Attribution Future Carbon&Future

Biophysical feedback, land cover change

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Impact on temperature