How it began
Camp Century was a U.S. Army research base built in tunnels inside the Greenland Ice Sheet about 200 kilometers from Thule, powered by a small nuclear reactor. Scientists were brought there to study snow and glacial ice. Chester C. Langway and B. Lyle Hansen set out to drill through the full thickness of the ice. The work took two different drills and five years. In the summer of 1966 the drill reached the bed, nearly 1.4 kilometers down, and recovered 3.4 meters of sediment from beneath the ice. The project was American; it was carried out in Greenland.
Before it existed
Shallow ice cores had been drilled around Greenland before, but to depths of no more than a couple of hundred meters. No core had reached the bed of any ice sheet, and no sample of the material under one had been recovered. Scientists therefore had no long, continuous record from deep polar ice.
How it works
A drill cuts a cylinder of ice, about 10.8 centimeters across at Camp Century, which is brought to the surface in sections. Because the ice built up layer by layer, deeper ice is older. Measuring oxygen isotopes in the water molecules, a property linked to atmospheric temperature, turns the core into a record of past climate.
What changed first
Isotope analysis of the Camp Century core produced a record of Earth's climate covering the last 100,000 years, which had not existed before. The clear ice was studied extensively. The 17 meters of debris-rich basal ice and the sediment below it received less attention at the time.
What lasted
The core catalyzed ice core science, and its data were later combined with those from newer deep cores in Greenland. The sediment was sent to Copenhagen in the early 1990s and forgotten in a freezer until it was found again in 2017. It contained twigs, moss and leaf fragments, showing that northwestern Greenland had been ice free and vegetated within the last million years.
Where it stands today
Results from the rediscovered sediment were published in 2021, and an American and European team received funding to analyze the full archive. Researchers use it to study how the ice sheet responded to past warmth and what that implies for sea level.
