the “natural” carbon cycle

speciation of CO2 in seawater

Geol. 5700-008

week 2

the long-term C-cycle

CO2 + H2O CH2O + O2 CaSiO3 + CO2 CaCO3 + SiO2

Berner ‘03

organic inorganic

natural carbon stocks and flowsocean

DIC: 38,000DOC: 600living C: 1

atmosphere700

sedimentary rocksCaCO3 + OC: 50,000,000

fossil fuels: 5000

landliving C: 500

dead C: 1500

60 GTC/y70

weatheringCaSiO3 + CO2 CaCO3 + SiO2

<0.1

metamorphismCaCO3 + SiO2 CaSiO3 + CO2

<0.1

stocks in GTC (gigatons C = 1015 g C)transfer fluxes in GTC/year

Archer ‘07

What is c-labile w.r.t met + wx?ocean

DIC: 38,000DOC: 600living C: 1

atmosphere700

sedimentary rocksCaCO3 + OC: 50,000,000

fossil fuels: 5000

landliving C: 500

dead C: 1500

60 GTC/y70

weatheringCaSiO3 + CO2 CaCO3 + SiO2

<0.1

metamorphismCaCO3 + SiO2 CaSiO3 + CO2

<0.1

stocks in GTC (gigatons C = 1015 g C)transfer fluxes in GTC/year

Archer ‘07

CO2 and temperature (Vostok, Ant.)

Petit et al. 1999

H-G perturbation budget (GTC)

• atm +170

• surface ocean +30

• biota +400 to +600

• deep ocean -600 to -800

~ Sundquist ‘93

quantificationG-H increase in atm. C burden by mass:

 

mass atm. in moles = 1.73E20M

CO2 mole fraction increase = 80 ppm = 80 M_c/M_atm

product = 1.38E22 uM_c= 1.38E16M_c = 13.8 petaM_c *12g/M_c = 166 PgC (=GTC)

 

Equilibrium increase in surface ocean DIC from homogenous ocean buffer factor (B) = 10:

 

∂pCO2_pert_atm/pCO2_init_atm= B * ∂DIC_pert_oce/DIC_init_oce

 

280 ppm CO2_pert_atm/ 200 ppm CO2_init_atm = 1.40 = +40%

 

0.4/10 * 900GTC_oce_init = +36 GTC

(see following TM presentation for full explanation of “B”)

 

Change in land biota (from simple whole ocean 13C mass balance constraint):

 

H-G 13C_oce = -0.3 per mil

 

present whole ocean 13C_abs = 0 per mil (by definition)

land biosphere  13C_avg = -20 per mil (mean photosynthetic discrimination)

38000 GTC_init (0 per mil) = X_pert GTC (-20 per mil) + (38,000 - X_pert GTC) (-0.3 per mil)

 

X_pert = +570 GTC

(per mil = ppt deviation from measurement standard)

glacial age physical perturbations

preindustrial

T= -1 K

S x 1.03

DIC+TA x 1.03

LGM

Zeebe & Wolf-Gladrow ‘01