From the ArcaMax Publishing, Science & Technology Newsletter:
http://www.arcamax.com/news/technology/s-638314-604992
COLUMBUS, Ohio (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.