From: Robin Blackstone, ENN
Published April 18, 2014 08:55 AM

Greenland was green

Greenland the second largest body of ice on Earth was actually green at one point in history. Researchers, including a scientist from Lawrence Livermore National Laboratory, have unearthed cryogenically frozen ancient dirt previously buried under nearly two miles of ice.


According to this research, Greenland looked like the green Alaskan tundra more than 2.5 million years ago. The dirty discovery will help us better understand what to expect with climate change. Specifically, how big ice sheets melted and grew in response to changes in temperature.

"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."

Preserved underneath the Greenland Ice Sheet is an ancient landscape that contains extremely large amounts of meteoric beryllium-10, suggesting that it once sat at Earth's surface for a long time before being covered in ice. Produced by cosmic rays, this type of beryllium-10 sticks to the soil after it rains onto the Earth’s surface.

The quantity of meteoric beryllium-10 atoms determines how long it sat on the surface.

"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.

Rood counted how many beryllium-10 atoms were in the dirt using the Center for Accelerator Mass Spectrometer (CAMS) at the Lab.

"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."

The last five years have yielded important advances in the ultra-sensitive and high-precision measurement of isotopes using AMS technology. This has increased the abilities of Earth scientists in understanding the response of ice sheets during climate change.

Read more at the Lawrence Livermore National Laboratory.

Greenland image via Shutterstock.

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