Solving an Ice Age Mystery

460 million years ago, the Appalachian Mountains in Eastern North America formed. 445 million years ago, the Earth dropped into an ice age so severe, two-thirds of all plants and animals went extinct. Coincidence? Seth Young and his colleagues say not, in this article.

In a write-up for ScienceNOW called "The Mountains That Froze the World", Phil Berardelli explains the theory and science behind the connection for the general public. Shortly after giant volcanic explosions formed the mountains,

...CO₂-laced acid rain fell on the rocks, [and] it formed limestone that washed into the Nevada sea and locked away huge amounts of carbon from the atmosphere. Then, when the volcanism ended, about 450 million years ago, the sequestering continued, thinning CO₂ levels to maybe a few times higher than today. Back then, a dimmer sun couldn't keep the atmosphere warm without CO₂'s help--hence, the eventual onset of the ice age.

These findings do not explain the reason the rise of the Himalayas was followed by an ice age, but they do give a reasonable explanation for this ice age. Among previous explanations was the idea that the ash blown up by the volcanoes themselves blocked the sun, but the dates didn't match.

The original findings published in Geology are a bit indecipherable to a non-scientist, but Berardelli's explanations are clear and much easier to follow. Head on over to ScienceNOW's website through the link above to see the whole article.

From Digg