COLUMBUS, Ohio, Oct. 28 (UPI) -- U.S. scientists says volcanoes around what is now the Atlantic Ocean caused the start of an ice age approximately 450 million years ago.
Ohio State University researchers said the volcanoes first caused global warming by releasing massive amounts of carbon dioxide into the atmosphere. But when they stopped erupting, Earth's climate was thrown off balance, and the ice age began.
Associate Professor Matthew Saltzman said that discovery underscores the importance of carbon in Earth's climate today.
Previously, Saltzman and his team linked the same ice age to the rise of the Appalachian Mountains. As the exposed rock weathered, chemical reactions pulled carbon from Earth's atmosphere, causing a global cooling that ultimately killed two-thirds of all species on the planet.
In the new study, the researchers determined giant volcanoes forming during the closing of the proto-Atlantic Ocean -- known as the Iapetus Ocean -- set the stage for the rise of the Appalachians and the ice age that followed.
"Our model shows that these Atlantic volcanoes were spewing carbon into the atmosphere at the same time the Appalachians were removing it," Saltzman said. "For nearly 10 million years, the climate was at a stalemate. Then the eruptions abruptly stopped, and atmospheric carbon levels fell well below what they were in the time before volcanism. That kicked off the ice age."
The study appears in the early online edition of the journal Geology.
