New research published this week in Nature, documents an Antarctic climate that was very different to the harsh, cold climate we now associate with this region.
Analyses carried out on an ocean sediment core collected off the Wilkes Land coast of East Antarctica contains pollen and spores from tropical plant species. These results indicate that 53 million years ago (m.y.a.), Antarctica contained tropical forest species, including palm trees. This was possible due to the relatively warm winter temperatures (more than 10 degrees C), and warm summer temperatures (maybe as high as 25 degrees C) recorded at this time.
The climate 53 m.y.a., during the Eocene, is of particular interest to climate scientists, since it is analogous to the possible future climate scenario under unchanged greenhouse gas emissions. During this time, carbon dioxide concentrations in the atmosphere were as high as 1000 ppm, and global temperature was much warmer than today.
Continued investigation into the climate of this time in Earth’s history provides us with a possible insight into how the climate may respond to human induced climate change, brought about by the release of large volumes of carbon dioxide into the atmosphere.
“There are two ways of looking at where we’re going in the future,” said a co-author of the study, James Bendle of the University of Glasgow.
“One is using physics-based climate models; but increasingly we’re using this ‘back to the future’ approach where we look through periods in the geological past that are similar to where we may be going in 10 years, or 20, or several hundred,” he told BBC News.
Dr Bendle said that as an analogue of modern Earth, the Eocene represents heightened levels of CO2 that will not be reached any time soon, and may not be reached at all if CO2 emissions abate.
However, he said the results from the Eocene could help to shore up the computer models that are being used to estimate how sensitive climate is to the emissions that will certainly rise in the nearer term.
“It’s a clearer picture we get of warm analogues through geological time,” he said.
“The more we get that information, the more it seems that the models we’re using now are not overestimating the [climatic] change over the next few centuries, and they may be underestimating it. That’s the essential message.”