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Greenland used to be green, and here’s why that’s bad news

Engineers pull up a section of the 4,560-foot-long ice core at Camp Century in the 1960s.

Ice core at Camp Century


April 15, 2021

Samples from a buried Cold War bunker reveal major past melting of Greenland’s ice sheet

A sample of soil collected deep beneath a Cold War ice bunker in Greenland has revealed that the largest ice sheet in the Northern Hemisphere, and a remnant of the last ice age, is more susceptible to a warming climate than previously thought. Plant material from the soil shows that, during a period in which global CO2 concentrations were much lower than they are today, the ice sheet was far smaller. With 40% of the global population living within 60 miles of the coast, faster melting of land-locked ice and the sea level rise that follows is not good news.

In 1959, the US Army constructed a secret cold war bunker, dubbed Project Iceworm, within the Greenland ice sheet 120 km (75 miles) from the coast. While the project was short-lived, the unique location allowed scientists to collect a 1.4 km (4,600 foot) long ice core from beneath the bunker, including nearly 4 meters (14 feet) of frozen soil. The cores were stored first at the University of Buffalo and then in a Danish repository before they were rediscovered and analyzed by an international interdisciplinary team including several NSF-funded researchers.

In the soil, researchers were shocked to find remnants of twigs and mosses. New age-dating techniques show that the soil formed sometime between 400,000 to 1 million years ago. While the Greenland ice sheet has survived through the 12,000 years since the end of the last great ice age, the new results show that during at least one warm interglacial period, the ice sheet shrunk long enough to allow formation of soil and establishment of plants in areas long buried in ice. Warm, interglacial periods have occurred periodically over the last 2 and a half million years, associated with the large-scale melting of continental ice sheets, dramatic sea level increases of 130 meters (460 feet), and increased CO2 in the atmosphere. As a result of fossil fuel use, current CO2 concentrations exceed the highest levels over anytime during the last one million years by nearly 50%.

These results, combined with other evidence that Greenland ice is melting at unprecedented rates, suggest the prospect of a melting Greenland ice sheet, and the resulting 7.2 meters (23 feet) of sea level rise, is much more likely than previously thought, highlighting the need for finding innovative ways to mitigate the effects of carbon emissions.

Christ et al. (2021) A multimillion-year-old record of Greenland vegetation and glacial history preserved in sediment beneath 1.4 km of ice at Camp Century. PNAS 118(3): e2021442118. https://doi.org/10.1073/pnas.2021442118

NSF grants EAR-1735676, EAR-1652274, and ARC-1023191 supported this study. Samples were prepared and data generated in community facilities funded by the NSF Division of Earth Sciences.

The U.S. National Science Foundation propels the nation forward by advancing fundamental research in all fields of science and engineering. NSF supports research and people by providing facilities, instruments and funding to support their ingenuity and sustain the U.S. as a global leader in research and innovation. With a fiscal year 2021 budget of $8.5 billion, NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and institutions. Each year, NSF receives more than 40,000 competitive proposals and makes about 11,000 new awards. Those awards include support for cooperative research with industry, Arctic and Antarctic research and operations, and U.S. participation in international scientific efforts.

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