Climate Science

Cause of Death

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Science  15 Aug 2008:
Vol. 321, Issue 5891, pp. 893
DOI: 10.1126/science.321.5891.893b

During the mass extinction event that occurred 200 million years ago, at the end of the Triassic Period, around half of all extant species vanished. In the marine realm, about 20% of all families and more than 90% of the genera in some groups of organisms disappeared. What caused that catastrophe? One hypothesis is that elevated atmospheric CO2 was the culprit, but evidence of that cause has been elusive. Hautmann et al. present data indicating that ocean acidification, possibly caused by high rates of magmatic CO2 degassing and thermal dissociation of marine gas hydrates, was responsible for the burst of marine extinctions. They show that carbonate sedimentation was interrupted globally, and that organisms that had skeletons of aragonite or high-Mg calcite were preferentially affected. Thus, it seems that high concentrations of atmospheric CO2 were in fact the proximal cause of the Triassic-Jurassic extinction event, a conclusion that has direct bearing on efforts to understand what may be the consequences of the buildup of atmospheric CO2 that now is underway. — HJS

Neues Jahrb. Geol. Palaeontol. Abh. 249, 119 (2008).

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