This chapter focuses on global-scale shifts in fundamental ocean carbonate chemistry due to increasing atmospheric CO2 concentrations from fossil-fuel combustion by humans. It reviews the current state of ocean pH and related carbonate system variables, how they have changed over the industrial era, and how they are expected to continue to change during this century. This anthropogenic problem is known as ocean acidification because rising CO2 concentrations are increasing ocean acidity (seawater pH is declining), although ocean surface waters are alkaline and will remain so. The basic chemistry is well understood, making future projections straightforward for the surface open ocean for a given atmospheric CO2 trajectory. Measured trends agree with those expected from the atmospheric CO2 increase. Uncertainties are larger for the high latitudes, deep ocean, coastal areas, and marginal seas. Establishing time series measurements in these areas is needed to improve understanding of present-day variability and improve future projections.
Orr J. C., 2011. Recent and future changes in ocean carbonate chemistry. In: Gattuso J.-P. & Hansson L. (Eds.), Ocean acidification, pp. 41-66. Oxford: Oxford University Press. Book.
