1. Ocean Acidification Reid Bergsund and Catherine Philbin
Image source:
Reid Bergsund and Catherine Philbin

2. Problem Ocean absorbs about 1/3 of excess atmospheric CO2
Carbonate buffer system regulates ocean pH
Lower ocean pH inhibits calcification for organisms with CaCO3 shells
Ocean absorption of atmospheric CO2 is causing the rate of acidification to increase
Image source:
Healthy Coral Reef

3. Ocean Chemistry 101—RealClimate
Carbonic acid dissociates and forms bicarbonate (HCO3-) and carbonate (CO32-) and excess hydrogen ions (H+)
An increase in hydrogen ions (H+) results in lowering the pH
Increasing CO2 decreases carbonate ions and inhibits the calcification reaction
CO2 + CO32- + H2O ⇔ 2HCO3-
Equilibrium reaction for CO2 in water
Ca2+ + CO32- ⇔ CaCO3
Image source: Ocean Chemistry 101
Calcification reaction

4. Ocean Acidification Review—Doney, et al (2009)
Understanding impacts of acidification has only been demonstrated in short- term experiments
Many questions surround organisms’ ability to adapt to increasing CO2 levels
Marine ecosystems are delicate and could be significantly affected by changes in the ocean’s chemical composition
Organisms’ responses varied to laboratory ocean acidification

5. Some Species May Benefit From Ocean Acidification—Iglesias-Rodriguez, et al (2008)
Exponentially grew coccolithophore and bubbled air containing various levels of CO2 through the culture mediums
Coccolithophore calcification and body volume significantly increased with high levels of aqueous CO2
Technical comment questions experimental methods

6. Question to Keep in Mind
How does increased atmospheric CO2 lower ocean pH?
What chemical processes are affected by increased ocean CO2 uptake?
What are the implications of demonstrating short- term experiments vs. long-term?
Historically, how have ocean biota responded to ocean acidification?
How will ocean biota respond to an unprecedented acceleration in ocean acidification?