Ancient Leaf Wax Tells the Story of Plant Life in Antarctica
The Southern Continent is so cold, that no substantial plant life can possibly survive, but this was not always so. A university-led study with participation from the National Aeronautic and Space Administration (NASA), has found evidence showing that ancient Antarctica was much warmer and wetter than previously believed. Sediment core samples were drilled beneath the Ross Ice Shelf, where they found remnants of plant leaf wax from 15 to 20 million years ago. From these remnants, the scientists could calculate that Antarctic temperatures used to be 20 degrees warmer than today and precipitation was higher. This glimpse into Antarctica's ancient past will help give clues as to what to expect in a warmer future.
Temperatures on the Antarctic coast possibly reached as high as 45 degrees F (7 deg C) in the distant past. This was enough to support substantial vegetation, including stunted trees along the edges farther from the South Pole.
The research team hypothesized that temperatures during the middle of the Miocene epoch were warmer than previously believed. This is due to the discovery of large quantities of pollen and algae in previously taken sediment cores around Antarctica by co-author Sophie Warny, assistant professor at LSU.
Team leader, Sarah J. Feakins of the University of Southern California in Los Angeles, then decided to examine the leaf wax remnants, which act as a record of climate change because they can document the hydrogen isotope ratios of the water the plant took up while it was alive. The leaf wax found suggested a much warmer Antarctic climate in the past.
The peak of the warm period took place in the middle of the Miocene, about 16 million years ago. At the time, carbon dioxide levels were around 400-600 parts per million (ppm). Today's level is 393 ppm, the highest it has been in the past several million years. At the current pace, carbon dioxide levels will reach the Miocene level by the end of the 21st century.
"The ultimate goal of the study was to better understand what the future of climate change may look like," said Feakins, an assistant professor of Earth sciences at the USC Dornsife College of Letters, Arts and Sciences. "Just as history has a lot to teach us about the future, so does past climate. This record shows us how much warmer and wetter it can get around the Antarctic ice sheet as the climate system heats up. This is some of the first evidence of just how much warmer it was."
This study has been published in the journal, Nature Geoscience
Image credit: NASA/JPL-Caltech/Dr. Philip Bart, LSU