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Environment

Ancient Antarctic Ice Discovered

2.7 million-year-old sample could tell us more about ice age cycles.

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John Higgins and his team camped at Alan Hills (above), where old ice is unusually accessible. | Preston Cosslett Kemeny/Princeton University Department of Geosciences

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Bubbles trapped in ice hold ancient air, giving geoscientists a way to date glacial ice in Antarctica. | Yuzhen Yan

American geoscientists have discovered 2.7 million-year-old ice — the oldest ever by 1.7 million years, researchers announced at the annual Goldschmidt conference in August. The sample was drilled from Antarctica’s Allan Hills “blue ice” area, where unusually old glacial ice is closer to the surface, making it more accessible.

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Geoscientist John Higgins (right) of Princeton University and his team drilled at three sites, hauling tents and equipment, such as a drill bit filled with an ice core. | Yuzhen Yan

Trapped bubbles can offer snapshots of past carbon dioxide and methane levels. This latest sample reveals Earth’s climate history beyond a critical benchmark when, 1 million years ago, glacial cycles shifted from 40,000- to 100,000-year periods. Understanding temperature and greenhouse gas shifts through those ice ages could also offer insights into Earth’s future climate.

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