Ken Caldeira of the Carnegie Institution’s Department of Global Ecology will present research today at the AGU/ASLO Ocean Sciences meeting in Honolulu that not only are carbon dioxide emissions making the world’s oceans more acidic, but that, if unabated, this acidity could cause a mass extinction of marine life similar to one that occurred 65 million years ago when the dinosaurs disappeared.

Caldeira’s models predict that the oceans will become far more acidic because, with fifty times more atmospheric carbon dioxide than normal, the natural buffering mechanism will be overwhelmed. In less than 100 years, the pH of the oceans could drop by as much as half a unit from 8.2 to about 7.7. The drop in ocean pH would be especially damaging to corals. (abstract)

The last time the oceans saw a change of this magnitude was 65 million years ago and it is presumed that the acidification was due to carbon dioxide emitted by limestone vaporised by the impact of an asteroid. The pattern of extinction was consistent with acidification because it was species with calcium carbonate shells that died off while animals with shells made from silicate minerals survived.

Tags: mass extinction, ocean acidity, carnegie institution’s department of global ecology, agu/aslo ocean sciences meeting, ken caldeira, atmospheric carbon dioxide