November 23, 2013
Acid Rain From Volcanic Eruptions, Depleting Ozone Contributed To End-Permian Extinction Event
April Flowers for redOrbit.com - Your Universe Online
At the end of the Permian period, approximately 250 million years ago, a mass extinction occurred that was so severe it remains the most traumatic known species die-off in Earth's history.Previous research has suggested that contemporaneous volcanic eruptions in Siberia might have triggered this extinction. A new study, published in the journal Geology, reveals that the atmospheric effects of these eruptions could have been devastating.
More than 90 percent of marine species and more than 70 percent of terrestrial species were included in the mass extinction. This set the stage for the rise of dinosaurs. According to the fossil record, ecological diversity did not fully recover until several million years after the main pulse of the extinction. Gas released from a large swath of volcanic rock in Russia, called the Siberian Traps, is one of the leading candidates for the extinction event.
The research team, led by Benjamin Black of MIT, used advanced 3D modeling techniques to predict the impacts of gas released from the Siberian Traps on the end-Permian atmosphere. The team included Jean-François Lamarque, Christine Shields, and Jeffrey Kiehl of the National Center for Atmospheric Research and Linda Elkins-Tanton, Director of Carnegie's Department of Terrestrial Magnetism.
The study findings suggest that volcanic releases of both carbon dioxide (CO2) and sulfur dioxide (SO2) could have created highly acidic rain, potentially leaching the soil of nutrients and damaging plants and other vulnerable terrestrial organisms. Global ozone collapse could have also been a result of the release of halogen-bearing compounds such as methyl chloride.
According to the team, the volcanic activity was most likely episodic. This would produce pulses of acid rain and ozone depletion. Combined with an overall temperature increase from greenhouse gas emissions, the drastic fluctuations in pH and ultraviolet radiation that were a result of the episodic activity could have contributed to the end-Permian mass extinction on land.