Caldeira Lab Research:Ocean acidification and ocean carbon cycle

Coral Reefs Under Rapid Climate Change and Ocean Acidification

O. Hoegh Guldberg, P. J. Mumby, A. J. Hooten, R. S. Steneck, P. Greenfield, E. Gomez, C. D. Harvell, P. F. Sale, A. J. Edwards, K. Caldeira, N. Knowlton, C. M. Eakin, R. Iglesias-Prieto, N. Muthiga, R. H. Bradbury, A. Dubi, M. E. Hatziolos

The oncoming effects of increased carbon concentration in the atmosphere on both temperature and the acidity of the ocean could have dire consequences for coral reefs by compromising carbonate accretion and causing a general decline in water quality. This is a study of possible future scenarios for coral reefs and the severe consequences they could have on those who depend on them.

Hoegh-Guldberg, O., P.J. Mumby, A.J. Hooten, R.S. Steneck, P. Greenfield, E. Gomez, D.R. Harvell, P.F. Sale, A.J. Edwards, K. Caldeira, N. Knowlton, C.M. Eakin, R. Iglesias-Prieto, N. Muthiga, R.H. Bradbury, A. Dubi and M.E. Hatziolos. Coral reefs under rapid climate change and ocean acidification, Science 318, 2007

CO2's chemical interaction with the ocean: When CO2 from the atmosphere is absorbed by the ocean, it reacts with water to produce carbonic acid, whose protons are released and combine with the carbonate ion. This decreases carbonate concentration, a crucial material to reef coral and other ocean creatures.

Visual representation of CO2's effect on ocean life: Photos from various locations in the Great Barrier Reef demonstrate the predicted conditions of coral reefs under extreme climate change.


Atmospheric carbon dioxide concentration is expected to exceed 500 parts per million and global temperatures to rise by at least 2°C by 2050 to 2100, values which significantly exceed those of at least the past 420,000 years, during which most extant marine organisms evolved. Under conditions expected in the 21st century, global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems. The result will be less diverse reef communities and carbonate reef structures that fail to be maintained. Climate change also exacerbates local stresses from declining water quality and overexploitation of key species, driving reefs increasingly toward the tipping point for functional collapse. This review presents future scenarios for coral reefs that predict increasingly serious consequences for reef-associated fisheries, tourism, coastal protection, and people. As the International Year of the Reef 2008 begins, scaled-up management intervention and decisive action on global emissions are required if the loss of coral-dominated ecosystems is to be avoided.