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13 September 2009
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.
"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."
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.
Eventually they discovered sediments of the right age near a traditional African village called Stakishari. By assembling a drilling rig and extracting hundreds of meters of samples from under the ground they were able to obtain exactly the piece of Earth's history they had been searching for.
Co-author Dr Gavin Foster from the University of Bristol Earth Sciences Department said: "By using the rather unique set of samples from Tanzania and a new analytical technique that I developed, we have, for the first time, been able to reconstruct the concentration of CO2 across the Eocene-Oligocene boundary - the time period about 34 million years ago when ice sheets first started to grow on Eastern Antarctica. "
The new findings offer important lessons for the future and will add to the debate around rising CO2 levels in the earth’s atmosphere as the world’s attention turns to on UN Climate Conference, which opens in Copenhagen later this year.
Co-author Dr Bridget Wade from Texas A&M University Department of Geology and Geophysics added: "This was the biggest climate switch since the extinction of the dinosaurs 65 million years ago.
"Our study is the first to provide a direct link between the establishment of an ice sheet on Antarctica and atmospheric carbon dioxide levels and therefore confirms the relationship between carbon dioxide levels in the atmosphere and global climate."
Cardiff University is recognised in independent government assessments as one of Britain’s leading teaching and research universities. Founded by Royal Charter in 1883, the University today combines impressive modern facilities and a dynamic approach to teaching and research. The University’s breadth of expertise in research and research-led teaching encompasses: the humanities; the natural, physical, health, life and social sciences; engineering and technology; preparation for a wide range of professions; and a longstanding commitment to lifelong learning. Cardiff is a member of the Russell Group of Britain’s leading research universities.
Visit the University website at: www.cardiff.ac.uk
University of Bristol
The University of Bristol is a member of the Russell Group and is consistently ranked among the leaders in UK higher education. According to The Times, it is among the top 40 universities in the world. Research-intensive and with an international reputation for quality and innovation, the University has 15,000 students from over 100 countries, together with more than 5,500 staff. In terms of the number of applications per undergraduate place, Bristol is arguably the most popular university in the country.
Atmospheric carbon dioxide through the Eocene-Oligocene climate transition. Paul N. Pearson1, Gavin L. Foster & Bridget S. Wade will be published in Nature online on Sunday 13th September.
A copy of the paper is available on request.
Further information is also available by contacting:
Tel: 029 208 74731
Dr Cherry Lewis
Research Communications Manager, University of Bristol
Tel: 0117 928 8086
Mob: 07729 421885
Dr Bridget Wade
Texas A&M University
Department of Geology & Geophysics
Tel: 979 862 7828
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