Ocean Acidification Victoria J. Fabry and Andrew G. Dickson Scripps Institution of Oceanography and California State University San Marcos fabry@csusm.edu

Atmospheric CO2 concentration at Mauna Loa Observatory, Hawaii

Atmospheric CO2 concentration at Mauna Loa Observatory, Hawaii Ocean pH at the Hawaii Ocean Time-Series Site

Effect of adding CO2 to seawater ↔ increases bicarbonate increase in dissolved CO2 decreases carbonate hydrogen ion concentration increases pH = –log [H+] decreases and the saturation state of calcium carbonate decreases

CO2 concentration in the atmosphere Measured

CO2 concentration in the atmosphere IPCC scenario A1FI Measured

Aragonite saturation state (from corals’ point of view) 1765 280 ppm Aragonite saturation state (from corals’ point of view) Extremely low Optimal

Aragonite saturation state (from corals’ point of view) 2010 390 ppm Aragonite saturation state (from corals’ point of view) Extremely low Optimal

Aragonite saturation state (from corals’ point of view) 2040 495 ppm Aragonite saturation state (from corals’ point of view) Extremely low Optimal

Aragonite saturation state (from corals’ point of view) 2080 788 ppm Aragonite saturation state (from corals’ point of view) Extremely low Optimal

1997 2008 Science, 2009

Distribution of excess CO2 in the oceans Sabine et al. (2004) & Doney (2006)