A Time-Series View of Changing Ocean Chemistry Due to Ocean Uptake of Anthropogenic CO2 and Ocean Acidification

Abstract

E C I A L I S S U E O N C H A N G I N G O C E A N C H E M I S T R Y » A N T H R O P O C E N E : T H E F U T U R E … Sand ocean acidification. The article discusses the long-term changes in dissolved inorganic carbon (DIC), salinity-normalized DIC, and surface seawater pCO 2 (partial pressure of CO 2 ) due to the uptake of anthropogenic CO 2 and its impact on the ocean's buffering capacity. In addition, we evaluate changes in seawater chemistry that are due to ocean acidification and its impact on pH and saturation states for biogenic calcium carbonate minerals.

Twenty Years of Marine Carbon Cycle Observations at Devils Hole Bermuda Provide Insights into Seasonal Hypoxia, Coral Reef Calcification, and Ocean Acidification

“…The human-mediated increase in atmospheric carbon dioxide (CO 2 ) and its uptake by the global ocean (Sabine et al, 2004;Khatiwala et al, 2013) has resulted in substantive changes in ocean chemistry and the marine CO 2 -carbonate system over the past few decades (e.g., Dore et al, 2009;Bates, 2012;Bates et al, 2014). The observed gradual decline in ocean pH and saturation states of calcium carbonate (CaCO 3 ) minerals (i.e., ) that results from ocean acidification (i.e., OA; Broecker et al, 1971Broecker et al, , 1979Caldeira and Wickett, 2003) and future end-ofcentury projections of ocean chemistry (e.g., Orr et al, 2005), constrained by emission scenarios of anthropogenic CO 2 , raise profound concerns about the potential consequences for marine calcifiers and ecosystems, in particular (e.g., Kleypas et al, 1999;Royal Society, 2005;Doney, 2006;Fabry et al, 2008;Doney et al, 2009).…”

Shifts in coral reef biogeochemistry and resulting acidification linked to offshore productivity

“…coral reef | ocean acidification | biogeochemistry | NAO | calcification O cean acidification (OA) resulting from rising atmospheric CO 2 (1)(2)(3) and the associated declines in surface seawater pH and saturation state with respect to CaCO 3 minerals such as aragonite (Ω aragonite = [Ca 2+ ][CO 3 2-]/K sp *, where K sp * is the ion solubility product) have raised concerns on the potential consequences to marine calcifiers and ecosystems (4,5). Reductions in Ω aragonite have been found to negatively affect organismal CaCO 3 production (6) while accelerating bioerosion and CaCO 3 dissolution (7,8).…”

Preface to special issue (Impacts of surface ocean acidification in polar seas and globally: A field-based approach)

“…The fundamental seawater chemistry is well understood and leads to predictions that surface seawater pH should decline in all oceans, with the single exception of regions where upwelling of deep waters occurs, where the recentlyupwelled surface seawater has not yet had time to exchange CO 2 with the higher concentrations now in Earth's atmosphere. This expectation is borne out by the records at the time-series sites which confirm that ocean acidification is a geographically global phenomenon (Bates et al, 2014). Nevertheless, the chemical impacts of ocean acidification are not equal in all locations, since seawater carbonate chemistry is changed from a different initial baseline in different locations.…”

“…Ocean acidification is not itself a consequence of global warming, but rather of the invasion of atmospheric CO 2 into the ocean. Time-series of carbonate chemistry measurements in different locations around the world all document the continuous and ongoing increase in the amount of CO 2 in the ocean, and the consequential accompanying decrease in surface ocean seawater pH at all sites over the last years (Bates et al, 2014).…”

“…Ocean acidification is not itself a consequence of global warming, but rather of the invasion of atmospheric CO 2 into the ocean. Time-series of carbonate chemistry measurements in different locations around the world all document the continuous and ongoing increase in the amount of CO 2 in the ocean, and the consequential accompanying decrease in surface ocean seawater pH at all sites over the last years (Bates et al, 2014).The 40% rise in atmospheric CO 2 levels over and above preindustrial values has led to a decrease in surface seawater pH of about 0.1 units, and if emissions continue to rise according to worst-case scenarios, as they have done until now, then at the end of this century (the year 2100) surface seawater pH may be about 0.4 units below preindustrial levels. The fundamental seawater chemistry is well understood and leads to predictions that surface seawater pH should decline in all oceans, with the single exception of regions where upwelling of deep waters occurs, where the recentlyupwelled surface seawater has not yet had time to exchange CO 2 with the higher concentrations now in Earth's atmosphere.…”