Pre-anthropogenic C cycle and recent perturbations

Control of atmospheric pCO2 on different time scales Time scale Components Processes 105 - 109 yrs lithosphere volcanism, burial, biosphere weathering 103 - 104 yrs hydrosphere ocean circulation and biosphere biogeochemical cycling, carbonate dissolution 10 – 102 yrs biosphere fossil fuel burning, land ecosystem shifts, land use changes

CO2 and temperature records 2009 (386 ppm)

Human perturbation of the global carbon budget 2000-2007 GtC fossil fuel emissions 7.5 83% Source deforestation 1.5 17% CO2 flux (Pg C y-1) atmospheric CO2 4.2 45% Sink land 2.6 29% Atmospheric CO2 accumulation is meaured/ The source terms are estimated from energy consumption and deforestation. The ocean sink is modelled The land sink is the residual from closing the balance (it is not directly measured). More details are: http://lgmacweb.env.uea.ac.uk/lequere/co2/carbon_budget.htm ocean 2.3 26% Time (y) Global Carbon Project (2008) 5

Land carbon cycling

Modelled land carbon storages as functions of pCO2 and T Gerber et al (2004), GCB

Climate-carbon model sensitivities to CO2 and T Friedensten et al (2006), JC

Ocean chlorophyll distribution

Air-sea exchange of CO2 from observations

“Observed” ocean uptake of anthropogenic CO2

DCESS Earth System Model Sun Atmosphere Ocean Land Biosphere Lithosphere Ocean Sediment (Shaffer et al (2008) in Geoscientific Model Development)

Model geometry and some components Atmosphere transport Land biomass Volcanic input Weathering River inflow

Ocean and ocean sediment submodels

Model fit to ocean data for standard parameter values

DCESS model simulation from 1765 to 2000 (1)

DCESS model simulation from 1765 to 2000 (2)

Standard vs no ocean heat uptake

Standard vs no ocean CO2 uptake

Standard vs no ocean heat nor CO2 uptake

Some positive climate feedbacks via oceanic CO2 *T   CO2 solubility   pCO2   T  *T  CP   pCO2   T  T   precip , winds   dust   NP   pCO2   T  T  MH   DIC   pCO2   T  (* included in the DCESS Earth System model)

Some negative climate feedbacks via oceanic CO2 * T   sea ice   NP   pCO2   T  *T   weathering   runoff   NP   pCO2   T  * pCO2  CO3   Alk   pCO2   T  pCO2  CO3   CP   pCO2   T  (* included in the DCESS Earth System model)

Scenario greenhouse gas and aerosol forcings Total anthropogenic carbon emissions (GtC) A2 3721 A1B 2398 B1 1536 AG 822 Total emissions by 2007 were 522 GtC.

Future Earth System projections for SRES B1 and A2 forcing (Shaffer et al. (2009) In Nature Geoscience)

1.5 million year run for doubling lithosphere CO2 outgassing

Methane Hydrate Present estimates of MH in the ocean sediment center around 10000 GtC For comparison, available fossil fuel resources are about 5000 GtC

MH release and ocean warming MH release leads to increased GHG forcing (CH4 and its oxidation product CO2) and warmer climate Warmer climate promotes the release of more MH as the ocean is warmed further Warming in the ocean leads to release of MH in ocean sediment Dickens 2003, Earth and Planetary Science Letters

DCESS Earth System Model Sun Atmosphere Ocean Land Biosphere Lithosphere Ocean Sediment CH4 Hydrate