Using an innovative technique to date one of Antarctica's ancient lake deposits, researchers have determined that the East Antarctic Ice Sheet, or EAIS, has remained frozen for the past 14 million years.
The work adds new support for the idea that the EAIS did not experience significant melting even during the Pliocene, a period from three to five million years ago, when carbon dioxide concentrations rivaled what they are today.
"The Pliocene is sometimes thought to be an analog to what Earth will be like if global warming continues," said one of the researchers Jane Willenbring, assistant professor at University of Pennsylvania in the US.
"This gives us some hope that the East Antarctic Ice Sheet could be stable in today's and future climate conditions," Willenbring noted.
Some scientists believe the ice sheet experienced significant melting during the relatively warmer conditions of the Pliocene, while others think it has remained almost entirely frozen for the last 14 million years.
Willenbring and colleagues hoped to help clarify the history of the EAIS. They traveled to Antarctica's Friis Hills in the central Dry Valleys of the eastern portion of the continent.
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About a foot beneath the surface are sediment deposits from an ancient lake which is known from animal fossils to have been freshwater.
With the use of a new technique, the researchers were able to estimate the age of the sediments to be between 14 and 17.5 million years ago.
"This means that the sediment is definitely older than the time when a lot of people think that Antarctica might have been quite deglaciated," Willenbring said.
The findings appeared in the journal Scientific Reports.