Sunday, September 13, 2009

New carbon dioxide data helps unlock the secrets of Antarctic formation

Science Daily: The link between declining CO2 levels in the earth's atmosphere and the formation of the Antarctic ice caps some 34 million years ago has been confirmed for the first time in a major research study.

A team of scientists from Cardiff, Bristol and Texas A&M universities braved the lions and hyenas of a small East African village to extract microfossils in samples of rocks which show the level of CO2 in the Earth's atmosphere at the time of the formation of the ice-cap. Geologists have long speculated that the formation of the Antarctic ice-cap was caused by a gradually diminishing natural greenhouse effect.

The study's findings, published in Nature online, confirm that atmospheric CO2 declined during the Eocene - Oligocene climate transition and that the Antarctic ice sheet began to form when CO2 in the atmosphere reached a tipping point of around 760 parts per million (by volume).

Professor Paul Pearson from Cardiff University's School of Earth and Ocean Sciences, who led the mission to the remote East Africa village of Stakishari said: "About 34 million years ago the Earth experienced a mysterious cooling trend. Glaciers and small ice sheets developed in Antarctica, sea levels fell and temperate forests began to displace tropical-type vegetation in many areas.

"The period, known to geologists as the Eocene - Oligocene transition, culminated in the rapid development of a continental-scale ice sheet on Antarctica, which has been there ever since….

Antarctic mountains and drifting ice, shot by Georges Nijs, Wikimedia Commons via Flickr, under Creative Commons Attribution 2.0 License.