<p>A team of scientists from Cardiff, Bristol and Texas A&M universities worked in Stakishari, a small East African village, to extract microfossils in rock samples which show the level of carbon dioxide at the time of the formation of the ice-cap.<br /><br />Geologists have long speculated that the formation of the Antarctic ice-cap was caused by a gradually diminishing natural greenhouse effect.<br /><br />The study establishes that atmospheric carbon dioxide declined during the Eocene-Oligocene climate transition and that the Antarctic ice sheet began to form when carbon dioxide in the atmosphere reached a tipping point of around 760 parts per million (by volume).<br /><br />Paul Pearson, professor in Cardiff University's School of Earth and Ocean Sciences, who led the mission, 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."<br /><br />"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.<br /><br />"We therefore set out to establish whether there was a substantial decline in atmospheric carbon dioxide levels as the Antarctic ice sheet began to grow."<br /><br />The team mapped large expanses of bush and wilderness and pieced together the underlying local rock formations using occasional outcrops of rocks and stream beds, said a Cardiff release.<br /><br />Eventually they discovered sediments of the right age near Stakishari. By assembling a drilling rig and extracting hundreds of metres of samples from under the ground, they were able to obtain exactly the piece of earth's history they had been searching for.<br />Co-author Bridget Wade, geologist from Texas A&M University, added: "This was the biggest climate switch since the extinction of the dinosaurs 65 million years ago." These findings were published in Nature online. <br /></p>
<p>A team of scientists from Cardiff, Bristol and Texas A&M universities worked in Stakishari, a small East African village, to extract microfossils in rock samples which show the level of carbon dioxide at the time of the formation of the ice-cap.<br /><br />Geologists have long speculated that the formation of the Antarctic ice-cap was caused by a gradually diminishing natural greenhouse effect.<br /><br />The study establishes that atmospheric carbon dioxide declined during the Eocene-Oligocene climate transition and that the Antarctic ice sheet began to form when carbon dioxide in the atmosphere reached a tipping point of around 760 parts per million (by volume).<br /><br />Paul Pearson, professor in Cardiff University's School of Earth and Ocean Sciences, who led the mission, 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."<br /><br />"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.<br /><br />"We therefore set out to establish whether there was a substantial decline in atmospheric carbon dioxide levels as the Antarctic ice sheet began to grow."<br /><br />The team mapped large expanses of bush and wilderness and pieced together the underlying local rock formations using occasional outcrops of rocks and stream beds, said a Cardiff release.<br /><br />Eventually they discovered sediments of the right age near Stakishari. By assembling a drilling rig and extracting hundreds of metres of samples from under the ground, they were able to obtain exactly the piece of earth's history they had been searching for.<br />Co-author Bridget Wade, geologist from Texas A&M University, added: "This was the biggest climate switch since the extinction of the dinosaurs 65 million years ago." These findings were published in Nature online. <br /></p>
