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Ocean Acidification

Scientific Basis

Geographic Extent
Scientific Basis
Management Decisions & Authorities, Recent Developments and Current Status
Processes and Effects

An increase in atmospheric CO2 results in an increase in the CO2 of the oceans, in turn the CO2 in the upper surface waters of the ocean will alter the oceanic carbon system.
As CO2 enters the oceans the following reactions take place:

CO2 + H2O  H2CO3

H2CO3 HCO3- + H+

HCO3- + H+ CO32- + 2H+

These reactions help show how pH decreases with addition of CO2 to ocean waters. From these we can deduce that calcification will decrease as well, since there is a decrease in surface CO32- concentration which will lead to a decrease in CaCO3 saturation state.

Exchange of CO2 between the ocean and atmosphere is so rapid, that the increase in concentration of CO2 in the atmosphere has already been seen to affect marine chemistry substantially.


Future predictions for the state of pH in the oceans have indicated an expected decrease of 0.3 to 0.4 units by 2100, such a decrease would have severe effects on organisms that make their shells out of calcite and aragonite because of destabilization of the these minerals, which in turn can have a drastic effect on marine ecosystems.



The Honolulu Declaration On Ocean Acidification and Reef Management - Shows projected increase in CO2


(Orr, 2005)

Geography of The Seas 2009
- Allison Walsh & Tyler Power

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