Parts of Antarctica were as Warm as Coastal California during Eocene Epoch, Yale Study

Around 40 to 50 million years ago, parts of Polar Regions were as warm as Coastal California, according to Yale University researchers.

The period called Eocene epoch witnessed high carbon dioxide levels and greenhouse climate conditions.

Antarctica, which currently registers annual average land temperatures several degrees below zero degrees Fahrenheit was once free of ice and had warm climate.

Understanding past climate conditions will help scientists understand how rise of greenhouse gases will affect ice in Polar Regions.

"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," Hagit Affek of Yale, associate professor of geology & geophysics.

For the study, researchers measured the levels of two rare isotopes, carbon-13 and oxygen-18. The isotopes were found bound together in fossil bivalve shells found by Linda Ivany of Syracuse University at Seymour Island, co-author of the study.

Researchers used a technique called carbonate clumped isotope thermometry to measure the abundance of the isotopes.

Researchers found that certain parts of Antarctica had temperatures as high as 17 degrees Celsius (63F) during the Eocene period. According to the researchers, these parts might have had a climate similar to that seen in California today.

Part of southern Pacific Ocean had temperatures that hovered around 22 degrees Centigrade (or about 72F), which is the temperature seen in today's Florida.

They verified their findings using geo-thermometers and model simulations.

"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 Peter M.J. Douglas, lead author of the study, according to a news release.

The study is published in the journal Proceedings of the National Academy of Sciences and was funded by the National Science Foundation, Statoil, and the European Research Council.