Frozen soil collected in Greenland during the Cold War, by a secret military operation, another secret was hidden: buried fossils that could be a million years old. Recent analysis has revealed that plants that are so well preserved that they ‘look like they died yesterday’, researchers said.
U.S. Army scientists dug up the ice core in northwest Greenland in 1966 as part of Project Iceworm, a secret mission to build an underground base that would hide hundreds of nuclear warheads, where they would be within striking distance of the Soviet Union. ‘A Arctic the research station, named Camp Century, was the Army’s cover story for the project. But iceworm foiled; the base was abandoned and the ice core lay forgotten in a freezer in Denmark until it was rediscovered in 2017.
When scientists studied the nucleus in 2019, they discovered fragments of petrified plants that may have bloomed a million years ago. The current ice cover of Greenland is believed to be almost 3 million years old, but the small plant fragments say otherwise and show that at one time or another in the last million years – possibly in the last few hundred thousand years – ice-free.
Related: Images of melting: the disappearing ice of the earth
Today, most of Greenland is covered by the Greenland Ice Sheet, which stretches 1.7 million square kilometers – about three times as large as Texas, according to the National Center for Snow and Ice (NSIDC).
If the new research turns out and most of Greenland’s ice has disappeared relatively recently, it does not bode well for the stability of its current ice sheet in response to human causes. climate change. If all the ice from Greenland melts, the sea will rise by about 7 meters National Oceanic and Atmospheric Administration (NOAA) reported in 2019. That would be enough to flood coastal cities worldwide, the researchers write in the new study, published in March. 15 in the journal Proceedings of the National Academy of Sciences.
Cold War Science
The U.S. Army Corps of Engineers began building Camp Century in 1959, and scientists BL Hansen and Chester Langway Jr. supervised the extraction of a 3.4-meter ice core from a depth of 1,488 meters below the ice. After the Army ended Project Iceworm, the nucleus was preserved, first at the State University of New York in Buffalo, where Langway was a researcher, and then at the Niels Bohr Institute in Copenhagen, said Andrew Christ, lead author of the new study, said. and a postdoctoral fellow and lecturer in the Department of Geology at the University of Vermont in Burlington.
‘The bottom of the ice core is these frozen pieces of sediment, about 10 centimeters [4 inches] long and ten inches wide, “Christ told WordsSideKick.” They put it in glass cake pots and labeled ‘Camp Century sub ice’ – and then forgot about it. ‘It was only in 2017 during an inventory of material that was bound. for a new freezer, when curator Jørgen Peder Steffensen recognized the lost nuclear samples. He immediately contacted researchers about investigating the sediments for the first time since the 1960s, Christ said.
‘When we found the fossils, it was one of the sciences’ Eureka! “Moments, it was completely unexpected,” Christ told WordsSideKick. When they rinse the frozen soil to sort it into different sized grains, they notice that ‘black black things’ are floating in the water. Christ placed some of the floating spots under a microscope, “and tree! There were fossil twigs and leaves in this frozen sediment,” Christ said. “The best way to describe it is freeze-dried. When we pulled it out and poured some water on it, it folded open slightly, so it looked like they died yesterday.”
Such plants – possibly from a boreal forest – can only grow on Greenland if the ice sheets of the island are mostly gone, so the next step was to find out how recently this happened, the authors of the study wrote.
Buried climate clues
To date, the scientists have looked at isotopes (variants of the same element with a different number of neutrons) of plants. aluminum and beryllium, which accumulate in minerals when exposed to radiation filtering through the atmosphere. These isotopes can tell scientists how long minerals have been exposed to the surface and how long they have been buried underground.
Based on isotope ratios, the study authors determined that the soil – and the plants that grow in it – last saw sunlight between a few hundred thousand and about a million years ago, the researchers report. Traces of leaf wax in the core sediments look similar to those of the current tundra ecosystems in Greenland.
The environmental isotope oxygen-18, found in ice trapped in the core of the sediment pores, provides further clues about this ancient ecosystem. Oxygen-18 in the core sediments was 6% to 8% higher than the average during the last part of the Holocene era; one explanation is that it came from precipitation that penetrated the soil at lower altitudes because the ice cover was scarce.
“We certainly had an ice-free northwestern Greenland at that time,” Christ said.
Based on geological records and geochemistry in the ocean, scientists have estimated that the current ice sheet of Greenland would continue for about 2.6 million years at the same size, the authors of the study write. However, their new findings show that ice has almost completely disappeared from Greenland during at least one period in the island’s recent freezing, which provides a previously unknown threshold for ice sheet stability.
In fact, scientists are already warning that Greenland is accelerating towards a critical tipping point of ice loss, with the prediction of the winter snowfall to replenish the seasonal meltdown by 2055, Live Science reported. in February.
“This is important as we move forward into a warmer future,” Christ said. “Our climate system has a fine balance. If it changes enough, you could melt away large parts of these ice sheets and raise sea levels – and it would flood and flood large parts of the most densely populated areas on earth.”
Originally published on Live Science.