Parts of ancient Antarctica were as warm as today's California coast 50 million years ago during the Eocene epoch, according to a new study.
Today, Antarctica is one of the coolest places on Earth and is covered in ice year-round. It has annual average land temperatures far below 0 degrees Fahrenheit. However, it wasn't always like that, researchers of Yale University found.
They conducted a study that looked into the structure of Antarctica during the Eocene epoch, 40-50 million years ago. This period is known have a greenhouse climate due to the high concentration of carbon dioxide in the atmosphere.
"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," study co-author Hagit Affek of Yale University said in a press statement.
For the study, researchers used geo-thermometers and model simulations to measure the concentrations of two rare isotopes bound to each other in fossil bivalve shells collected by co-author Linda Ivany of Syracuse University at Seymour Island. The concentration of bonds between carbon-13 and oxygen-18 reflect the temperature in which the shells grew.
These measurements led to the discovery that temperatures in parts of Antarctica reached as high as 17 degrees Celsius and averaged at 14 degrees Celsius, which are temperatures similar to that of the Californian coasts today.
Researchers also found that part of the southern Pacific Ocean had Eocene temperatures that were around 22 degrees Celsius, which is similar to the seawater temperatures of Florida in the current day scenario. Now, the same region has temperatures similar to that of Antarctica, which is about 0 degrees Celsius.
"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.
"We now know that it was warm across the continent, but also that some parts were considerably warmer than others. 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."
Researchers hope that the new findings can help improve climate models used for predicting future climate. The study was supported by The National Science Foundation, Statoil, and the European Research Council. The findings were published online in the Proceedings of the National Academy of Sciences.
