Unveiling the Mystery of the Antarctic Ice Sheet
29.02.2008 - Other
Scientists from Cardiff University's School of Earth and Ocean Sciences and from Amgueddfa Cymru, the National Museum of Whales, have revealed further records revealing a temperature decrease during the Antarctic ice sheet formation, which occurred during the Eocene-Oligocene (E-O) climate transition.
The scientists analysed ancient sea floor mud which was recovered from Tanzania, East Africa, revealing indirect evidence for an approximate 2.5°C ocean cooling during the period preceding the Antarctic ice sheet formation. By analysing the shell chemistry of deep-sea benthic foraminiferal microfossils, they found that delta O18 had increased during this period, a proxy sign for temperature change.
Recent studies explained the Antarctic ice sheet formation by a change in the Earth's orbit, high-latitude cooling, changes in moisture transport, or a sudden/gradual global cooling effect. It is expected that previous temperature records showed no evidence of the oceans having cooled during the Antarctic ice sheet formation, possibly due to a saturation effect on benthic foraminiferal Mg/Ca ratios at deep-water sites. These new results, however, point towards a tropical surface-water temperature decrease and support a global-cooling theory.
