1.2 million year old ice drilled out
The oldest ice in the world is found in the Antarctic. A borehole has now produced a new record for the oldest ice that science has ever recorded
The Little Dome C research camp in Antarctica is probably one of the most remote places on Earth where people settle, at least temporarily. However, an important step has been taken here to analyse the Earth's climate history more precisely. An international research team led by Frank Wilhelms from the Helmholtz Centre for Polar and Marine Research in Bremerhaven extracted a 2800-metre-long ice core from the Antarctic ice sheet that spans at least 1.2 million years without interruption. This significantly extends the previous record of 800,000 years of climate history from a drill core obtained in 2004.
The new borehole reached the bottom of the glacier, where it rests on rock. Each metre of ice covers up to 13,000 years of climate history, with the lowest 210 metres of the ice core above the bedrock consisting of old ice that is heavily deformed, possibly mixed or refrozen and of unknown origin. It may therefore not be useful for analyses. In the area between 2426 and 2490 metres, on the other hand, lies the transition of the middle Pleistocene: a period in which the ice age cycles slowed down from 41,000-year intervals to 100,000-year intervals. Why this happened will be analysed using data from these ice cores, among other things.
The valuable sample material is to be transported back to Europe on board the icebreaker Laura Bassi. A logistically complex endeavour: Among other things, a cold chain of minus 50 degrees Celsius must be maintained in order to optimally protect the ice. After all, the gas bubbles trapped in the ice should not be released during thawing, as they contain important information about the composition of the atmosphere at that time, for example.
Spectrum of Science
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Original article on Spektrum.de
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