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.
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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.