Antarctica Was Once As Warm As California, Florida: Study

By Terrell Johnson
Published: April 24, 2014

On the left, an aerial view of Antarctica today. Did it once look more like this scene on the right, from the Florida Keys?

Today it's one of the coldest places on Earth, but millions of years ago parts of the Antarctic region had a climate that Californians and Floridians would find familiar, according to a study released this week in the Proceedings of the National Academy of Sciences.

During the Eocene epoch, about 40 to 50 million years ago, when atmospheric concentrations of carbon dioxide were much higher than today's, temperatures in parts of Antarctica rose as high as 63 degrees Fahrenheit, and averaged about 57 degrees Fahrenheit.

That's about the same as temperatures off the coast of California today, a far cry from the bitter cold found in the present-day Antarctic interior, where temperatures stay well below zero degrees Fahrenheit and even dropped to a record -135.8 degrees Fahrenheit last year.

Temperatures were even higher during the Eeocene in the southern Pacific Ocean near Antarctica, the study found, reaching about 72 degrees Fahrenheit, as warm as the waters off the coast of Florida today.

These findings, which shed new light on just how warm Earth's polar regions can become and the risks of rising global sea levels, come from a newly developed method for measuring ancient temperatures in the fossil record.

Using fossil bivalve shells collected by study co-author Linda Ivany on Seymour Island, a small island off the coast of the Antarctic Peninsula, the scientists who led the study measured the shells' concentrations of a pair of isotopes -- carbon-13 and oxygen-18 -- to determine the climate in which they grew.

Next, the scientists combined the isotope measurements with readings from geo-thermometers and computer model simulations of the Antarctic climate. They call this new technique "carbonate clumped isotope thermometry."

Perhaps what is most interesting for the average reader today is the insight the study provides into how dramatically Earth's climate can change, and how sensitive it is to increases and decreases in concentrations of greenhouse gases (like carbon dioxide) in the atmosphere.

"By measuring past temperatures in different parts of Antarctica, this study gives us a clearer perspective of just how warm Antarctica was when the Earth's atmosphere contained much more CO2 than it does today," said Yale University scientist Peter M.J. Douglas, the study's lead author.

"Quantifying past temperatures helps us understand the sensitivity of the climate system to greenhouse gases, and especially the amplification of global warming in polar regions," added Hagit Affek, also a scientist at Yale and one of the study's co-authors.

"We now know that it was warm across the continent, but also that some parts were considerably warmer than others," noted Douglas. "This provides strong evidence that global warming is especially pronounced close to the Earth's poles.

"Warming in these regions has significant consequences for climate well beyond the high latitudes due to ocean circulation and melting of polar ice that leads to sea level rise."

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