Author: Carolyn Gramling / Source: Science News

Just beyond the tip of the Antarctic Peninsula lies an iceberg graveyard.
There, in the Scotia Sea, many of the icebergs escaping from Antarctica begin to melt, depositing sediment from the continent that had been trapped in the ice onto the seafloor. Now, a team of researchers has embarked on a two-month expedition to excavate the deposited debris, hoping to discover secrets from the southernmost continent’s climatic past.
That hitchhiking sediment, the researchers say, can help piece together how Antarctica’s vast ice sheet has waxed and waned over millennia. And knowing how much the ice melted in some of those warmest periods, such as the Pliocene Epoch about 3 million years ago, may provide clues to the ice sheet’s future. That includes how quickly the ice may melt in today’s warming world and by how much, says paleoclimatologist Michael Weber of the University of Bonn in Germany.
Weber and Maureen Raymo, a paleoclimatologist at Lamont-Doherty Earth Observatory in Palisades, N.Y., are leading the expedition, which set sail on March 25.
“By looking at material carried by icebergs that calved off of the continent, we should be able to infer which sectors of the ice sheet were most unstable in the past,” Raymo says. “We can correlate the age and mineralogy of the ice-rafted debris to the bedrock in the section of Antarctica from which the bergs originated.”
Iceberg Alley ahoy
Icebergs breaking off from the edges of Antarctica’s ice sheet tend to stay close to the continent, floating counterclockwise around the continent. But when the bergs reach the Weddell Sea, on the eastern side of the peninsula, they are shunted northward through a region known as Iceberg Alley toward warmer waters in the Scotia Sea.
Because so many icebergs from all around the continent converge in one region, it is the ideal place to collect sediment cores and take stock of the debris that the bergs have dropped over millions of years.
“That area in the Scotia Sea is so exciting, because it’s a focus point between South America and the Antarctic Peninsula where the currents flow through, and there are a lot of icebergs,” says Gerhard Kuhn, a marine geologist at the Alfred Wegener Institute in Bremerhaven, Germany. “You get a picture of more or less [all of] Antarctica in that area,” says Kuhn, who…
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