A study published in the June 17, 2012, issue of the journal Nature Geoscience indicated that summers in Antarctica 16 million years ago were 20° F (11°C) warmer than today. Sediment core samples taken from under the Ross Ice Shelf showed that Antarctica climate was warm enough to foster substantial plant growth, including small trees.
The study, led by Sarah J. Feakins of the University of Southern California, and which included research scientists from NASA’s Jet Propulsion Laboratory in Pasadena and Louisiana State University in Baton Rouge, also found that precipitation levels in Antarctica at that time were several times higher than today.
The one link that connects the climate of then to now is the CO2 level. The carbon dioxide levels at that time were estimated to be between 400 to 600 parts per million (ppm). In 2012, CO2 in earth’s atmosphere had risen to 393 ppm, the highest it has been in the past several million years, and very close to the levels that existed in earth’s climate 16 million years ago.
At the present time, the continuous burning of fossil fuels pumps approximately 30 billion tons of CO2 emissions into the air every year. At the current rate of increase, atmospheric carbon dioxide levels are on track to reach the 400 to 600 ppm range by 2100.
Study co-author and JPL scientist Jung-Eun Lee has created experiments to analyze climate behavior under such high-temperature, high-CO2 conditions. He said, “When the planet heats up, the biggest changes are seen toward the poles. The southward movement of rain bands associated with warmer climate in the high-latitude southern hemisphere made the margins of Antarctica less like a polar desert and more like present-day Iceland.” Presumably, that means rain bands in the northern hemisphere would move toward the north pole, leaving earth’s present temperate zones hot and dry.
Personal note from the author: my novel Red Hot Sky is based on a similar, but more dramatic, scenario.