Thirty-four million years ago, Antarctica froze over. The continent became covered in a huge sheet of ice and the temperature dropped. However, a recent study by Sarah Feakins from the University of Southern California suggests that Antarctica’s climate has not been steadily freezing cold since that most recent glaciation. In ocean sediment, scientists have uncovered evidence of pollen and leaf wax that existed on the continent 15.5 to 20 million years ago. This could mean that during this period of time, known as the Middle Miocene, a higher amount of rain, correlated with warmer temperatures, allowed trees to grow on Antarctica. Using samples gathered from a drilling project in 2007 known as the Andrill Project, Feakins and her colleagues discovered that there were two separate spikes in temperatures in Antarctica. At 16.4 and 15.7 million years ago, the temperature was approximately 7 degrees Celsius (45 degrees Fahrenheit) during the summer, versus the -4 degrees C (25 degrees F) that it is today. These warming periods, each lasting approximately 30,000 years, allowed podocarp conifers and southern beech trees to grow on the continent. During the Middle Miocene, the Earth as a whole was warmer, but only by approximately 4 degrees overall. The fact that Antarctica was as much as 11 degrees warmer than today gives credibility to the idea of “polar amplification”—a phenomena whereby the polar areas of the Earth get warmer in hotter times than do the areas close to the equator. These findings could be a warning of what global climate change could mean for the polar regions today.
Read more about the study and polar amplification at Earth: The Science Behind the Headlines.
The published study can be found in a June 2012 issue of the journal Nature Geoscience.