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Antarctic project to drill for oldest-ever ice core

March 27, 2019 This article courtesy of Nature News.

International team plans to extract 1.5-million-year-old ice that holds secrets about the planet’s ancient climate.

Geoscientists are getting ready to dig up ice that is older than anything ever excavated before.

After two years of extensive reconnaissance in Antarctica, an international team of researchers is set to drill for a core that is likely to contain ice at least 1.5 million years old, and that should reveal details about the planet’s ancient climate.

The Beyond EPICA project, which the European Commission is expected to fund with about €11 million (US$12.5 million) in grants, is set to start formally in June. Next year, scientists on the team, which includes 12 groups from 10 European countries, plan to set up camp in an area of East Antarctica called little Dome C, and start drilling to the bottom of the 2.75-kilometre-thick ice sheet at a site there.

“I’m absolutely thrilled,” says principal investigator Carlo Barbante, a climate scientist at the Ca’ Foscari University of Venice in Italy and at the National Research Council of Italy. “This iconic project will help us better understand climate change in the past and to come.”

Millenia of ice

Ice that has accumulated undisturbed over millennia preserves samples of the world’s ancient atmosphere, creating a continuous climate record with high temporal resolution. Existing records from Greenland and Antarctica shed light on what drives Earth’s glacial cycles, and how climate fluctuations correlate with the amount of greenhouse gases in the atmosphere.

Deep cores drilled by the European Project for Ice Coring in Antarctica (EPICA) more than a decade ago cover the climate and greenhouse-gas history of the past 800,000 years. The cores showed that, over this time, there were 8 pronounced glacial cycles that each lasted nearly 100,000 years. The new core will extend the record to a period when the pattern of climate variability was markedly different.

Marine sediments suggest that, before about one million years ago, the climate oscillated in 40,000-year cycles. Barbante says that a 1.5-million-year-old ice core will provide clues to what caused the transition — a major question in the Earth and climate sciences.

Barbante thinks that it will take four years to complete the mechanical drilling. The team will begin its mission next year, by lowering a tube with a cutting head into a casing inserted in the topmost 100 metres of ice. A drilling liquid will prevent the borehole from closing.

Proper drilling into the ice sheet will proceed in the 2020–21 Antarctic field season. Ice-deposition models and exploration at the site, including several reconnaissance drills and radar measurements taken from the air, suggest that the oldest ice at the bottom of the sheet is undisturbed by melting or folding.

“We’re very confident that the bottommost 300 metres have the missing climate information that we want to find,” says Barbante. The French–Italian Concordia Station, about 40 kilometres northeast of the drilling site, will provide logistical and medical support throughout the five-year project.

Meanwhile, Australian researchers are looking for an appropriate site at which to drill for a separate deep ice core nearby. A team hopes to establish camp on little Dome C in January 2021. With logistical support from Concordia Station, drilling could start later that year, or in 2022.

“We don’t see it as a race or competition,” says Tas van Ommen, a glaciologist with the Australian Antarctic Division in Hobart, who leads the Aus$50-million (US$36-million) project. “There’s plenty of room for friendly cooperation.”

A second core would be extremely desirable for replication purposes, says Barbante. “Two is better than one,” he says. “You can never be confident in a single record. And, whoknows, just a few kilometres apart might tell a completely different story.”


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