Sulphur-laden skies from massive eruptions may have ended dinosaurs

by Rich Bowden - Mar 21 2008, 03:41

New evidence has said dinosaurs succumbed to an increasingly sulpherous and climate-cooling atmosphere caused by massive volcanic eruptions at the Deccan Traps, in west-central India 65 million years ago.

The theory relegates the the famous Chicxulub meteor impact under the Yucatan Peninsula in Mexico played at best an ancillary role in their  demise. 

Geologist Stephen Self of the U.K.'s Open University in Milton Keynes has said the poisonous gases released by the eruptions led to the mass extinctions.

The new study is one of a series which backs the Deccan Traps' role in the ending of the dinosaur era. The theory is known as the K-T mass extinction event.

"A semi-persistent gas release of hundreds to thousands of teragrams of (sulphur dioxide) per year can be envisaged for each Deccan eruption," Self and his team report.

Speaking to Discovery News, Self added: "There's plenty of it, and it would be pumped into the atmosphere."

Yet little is known of the behaviour of sulphur dioxide in the Earth's atmosphere.

While carbon dioxide tends to stay for many years, acting as a climate blanket, sulphur dioxide reflects sunlight back into space, thereby cooling the climate. However evidence suggests the sulphur spends less time in the Earth's atmosphere, so its cooling effect would have lasted only a little time after the eruptions.

The largest of the Deccan Traps volcanos spewed basalt lava east across the continent and into the sea. To gain an idea of the strength of the massive volcano, the 1991 Mount Pinatubo volcano on the Philippines was 1000 times less powerful says Self.

 

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