Greenland, the icy island nation in the Arctic, gets its name from an Icelandic murderer exiled there, who called it "Greenland" in hopes that the name would attract settlers. But it turns out that long ago, Greenland was actually quite green.
A new study of the world's largest island reveals that ancient dirt in Greenland was cryogenically frozen for millions of years underneath about 2 miles of ice.
"More than 2.5 million years ago Greenland looked like the green Alaskan tundra, before it was covered by the second largest body of ice on Earth," the Lawrence Livermore National Laboratory said in a statement Thursday.
Greenland's ancient dirt tells a story of climate change - huge ice sheets melting and growing in response to changing temperatures.
"Our study demonstrates that the ice in the center of the Greenland Ice Sheet has remained stable during the climate variations of the last millions of years," said Dylan Rood, a former Lawrence Livermore scientist. "Our study adds to a body of evidence that shows how major ice sheets reacted in the past to warming, providing insights into what they could do again in the future."
Rood and his collaborator's research appears in the journal Science Express.
According the the researchers, Greenland's ancient landscape is preserved beneath its ice sheet. The meteoric beryllium-10 present in an analysis of the ancient dirt suggests that it once sat at the Earth's surface for a long time before Greenland was covered in ice. Meteoric beryllium-10 literally rains down onto the Earth's surface when cosmic rays hit the atmosphere, the researchers said, noting that the element gets stuck in soil.
The more meteoric beryllium-10 atoms present in soil, the longer the soil sat at the surface. Researchers can count the number of atoms in the dirt using an accelerated mass spectrometer. Rood used equipment at the Center for Accelerator Mass Spectrometry (CAMS) to make the measurements.
"It is amazing that a huge ice sheet, nearly two miles thick and the second largest body of ice on Earth, didn't scrape it away," said Rood, who now works at the Scottish Universities Environmental Research Centre.
"The trick, of course, is isolating the extremely rare beryllium-10 atoms from the million billion beryllium-9 atoms in our samples," Rood said. "I'm always amazed to see how a pinhead-sized sample from dirt can be ionized and accelerated through the maze of beamlines in CAMS and then go exactly where it needs to go in order to allow us to count its individual atoms. The CAMS allows us to count these very rare beryllium-10 atoms, which is analogous to finding the one grain of sand that is different than the rest on a beach."
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