title: Simulated effect of calcification feedback on atmospheric CO2 and ocean acidification.
abstract: Ocean uptake of anthropogenic CO2 reduces pH and saturation state of calcium carbonate materials of seawater, which could reduce the calcification rate of some marine organisms, triggering a negative feedback on the growth of atmospheric CO2. We quantify the effect of this CO2-calcification feedback by conducting a series of Earth system model simulations that incorporate different parameterization schemes describing the dependence of calcification rate on saturation state of CaCO3. In a scenario with SRES A2 CO2 emission until 2100 and zero emission afterwards, by year 3500, in the simulation without CO2-calcification feedback, model projects an accumulated ocean CO2 uptake of 1462 PgC, atmospheric CO2 of 612 ppm, and surface pH of 7.9. Inclusion of CO2-calcification feedback increases ocean CO2 uptake by 9 to 285 PgC, reduces atmospheric CO2 by 4 to 70 ppm, and mitigates the reduction in surface pH by 0.003 to 0.06, depending on the form of parameterization scheme used. It is also found that the effect of CO2-calcification feedback on ocean carbon uptake is comparable and could be much larger than the effect from CO2-induced warming. Our results highlight the potentially important role CO2-calcification feedback plays in ocean carbon cycle and projections of future atmospheric CO2 concentrations.
authors.affiliation: School of Earth Sciences, Zhejiang University, Hangzhou, Zhejiang 310027, China.
authors.forename: Han
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Earth Sciences, Zhejiang University, Hangzhou, Zhejiang 310027, China.|State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Hangzhou, Zhejiang, China.
authors.forename: Long
authors.initials: L
authors.lastname: Cao
mesh_terms: D000465:Algorithms; D001272:Atmosphere / Q000737:chemistry*; D002119:Calcium Carbonate; D002244:Carbon / Q000032:analysis; D002245:Carbon Dioxide / Q000032:analysis*; D017753:Ecosystem; D025461:Feedback, Physiological; D009792:Oceans and Seas; D012623:Seawater / Q000737:chemistry*
chemical_list: D002245:Carbon Dioxide; D002244:Carbon; D002119:Calcium Carbonate
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