Ancient global warming 'triggered' by volcanoes
Volcanic eruptions pushed greenhouse gases into the atmosphere
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Friday, 27, Apr 2007 12:25
Massive volcanic eruptions about 55 million years ago near Greenland and Europe triggered a period of global warming, scientists said today.
During this period, known as the Paleocene-Eocene thermal maximum (PETM), sea surface temperatures rose by five degrees C in the tropics and more than six degrees C in the Arctic.
PETM lasted for 220,000 years and the eruptions, which pushed Greenland and north-west Europe apart to create the north Atlantic ocean, also resulted in increased acidification of the world's oceans and the extinction of numerous deep-sea species.
Researchers from three universities made the link between the eruptions and global warming after measuring the amounts of argon gas trapped in volcanic minerals.
"There has been evidence in the marine record of this period of global warming, and evidence in the geologic record of the eruptions at roughly the same time, but until now there has been no direct link between the two," said researcher Robert Duncan, a professor in the College of Oceanic and Atmospheric Sciences at Oregon State University.
Another author of the report, Carl Swisher, professor of geological sciences at Rutgers, the state university of New Jersey, added: "Marine records document a sudden release of carbon dioxide, known as the carbon isotope excursion, accompanied with an increase in ocean acidity and the extinction of many deep-sea species.
"Now, for the first time, geologists have a precise correlation to link the sudden increase in volcanic activity and spike in greenhouse gases."
Published in the journal Science today, the researchers argue that the link between eruptions and global warming is important as it shows Earth's response to the release of large amounts of greenhouse gases (carbon dioxide and methane) into the atmosphere.