A New Explanation for Ancient Mass Extinction

By Brandon Keim

April 6, 2009 | 11:17 am |

Categories: Environment

A new explanation for the most massive extinction in Earth's history could have a very modern lesson.

German and Russian climatologists say that toxic gases emitted by giant salt lakes 250 million years ago could have caused the Permian-Triassic die-off, during which 90 percent of all terrestrial plant and animal species perished.

Previous explanations included volcanic eruptions and asteroid strikes that could have shrouded the planet in dust, or the oceanic release of atmosphere-choking methane hydrate.

But when they measured the emissions of salt seas in southern Russia, the researchers realized that the Zechstein Sea — a France-sized, hyper-saline inland ocean located in what is now Central Europe — could have emitted enough chlorine gas to cause mass plant die-offs, triggering a chain reaction of ecological catastrophe.

The size and evaporation rates of modern salt seas are expected to increase as the planet warms. The researchers don't expect that our seas will cause another extinction event, but say their toxic effect is underestimated by climate modelers.

Citation: "Late permian changes in conditions of the atmosphere and environments caused by halogenated gases." By L. Weissflog, N. F. Elansky, K. Kotte, F. Keppler, A. Pfennigsdorff, C. A. Lange, E. Putz and L. V. Lisitsyna. Doklady Akademii Nauk, Doklady Earth Sciences, Vol. 424, No. 6, April 2009.

Source: Wired