Global atmospheric carbon dioxide concentrations have
increased significantly from pre-industrial levels of c.280 ppmv
to approximately 390 ppmv today (Earth Science Research
Laboratory Global Monitoring Division 2012) as a result of
human activity [1]. The world’s oceans are a carbon sink and have
absorbed nearly a third of all anthropogenic CO2 since 1800,
without which atmospheric levels would be much higher than they
are now [2]. To date, changes in marine carbon chemistry as a
result of CO2 uptake include reductions in seawater pH, carbonate
ion concentration, and aragonite (CaCO3) saturation state [3].
Projections under the Intergovernmental Panel on Climate
Change (IPCC) A1F1 scenario suggest that atmospheric CO2 will
increase to ,1000 ppmv by the year 2100 [4,5], with further
increases up to 2000 ppmv by the year 2300 [1]. These increasing
atmospheric concentrations will lead to further reductions in the
global average surface-water pH of 0.3–0.4 units by the year 2100
[6]. Coastal and high latitude pH levels may be decrease more and
reductions will likely occur sooner [1,7].