Volcanoes and the Great Dying

Reported by Raleigh McElvery ’16

Volcano (illustration credit: Abby McBride)

Catastrophe struck in 1783 when a volcanic fissure in Iceland belched forth a lethal fog of hydrofluoric acid that spread across Europe, devastating the landscape and its inhabitants along the way. But according to volcano expert Dr. Lindy Elkins-Tanton, that was nothing compared to the Siberian Flood Basalts eruption of 252 million years ago – which caused a change in climate that may be to blame for the largest extinction in history.

In a recent lecture titled ‘Volcanoes and the Great Dying,’ hosted by Bowdoin’s Earth and Oceanographic Science Department, Elkins-Tanton drew parallels between that major atmospheric change and the one going on today.

Elkins-Tanton is the director of the Department of Terrestrial Magnetism at the Carnegie Institution for Science, a Mineralogical Society of America Distinguished Lecturer, and an expert on all things volcano. To give her audience an idea of scale of the Siberian cataclysm, she compared the volume of various eruptions by representing their “spewage” in a series of cubes of increasing size. Mount St. Helens lay on the far left, with just one cubic kilometer. The Iceland eruption was next, followed by a string of other eruptions. The Siberian eruption cube, farthest to the right, outsized them all by a landslide.

It started with “burps” of basalt magma, Elkins-Tanton said: very large, very powerful burps that expelled almost 3,000,000 cubic kilometers of materials. Lava from the flood basalts engulfed a large basin (known as the Siberian craton) and the volcanic materials vaporized, releasing chemicals into the atmosphere.

Though that cataclysmic event coincided with the Great Dying, as the end-Permian extinction is known, scientists have disagreed about whether it was actually the cause. So Elkins-Tanton set out to dig up the truth. She joined a team of 30 scientists from eight countries that launched five expeditions to Russia over the past decade.

By analyzing samples of basaltic rocks and using climate modeling, the team found evidence that sulfur, chlorine, fluorine, and carbon were released during the Siberian eruption, radically altering atmospheric chemistry, ocean chemistry, and climate – likely with widespread repercussions for both marine and terrestrial life. The sulfur probably generated acid rain, while the combination of chlorine, fluorine and carbon would have damaged, and even destroyed, parts of the ozone layer.

“We think that we nailed it,” Elkins-Tanton said. “We have the measurements that show the climate change, we have the climate models that show just how bad that change was, and we’ve got the geochronology.” While more questions remain to be answered, the discovery could have pressing implications in light of current climate change.

“What we’re going through today is a frightening parallel to what happened at the end-Permian,” Elkins-Tanton said.

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