by JAY R. THOMPSON
Antarctic ice sheets can be unforgiving field sites for scientists looking for fossils, as the ice grinds and pulverizes signs of previous life. The adjacent ocean sediments, however, are a good hiding place for microscopic fossils from plants — pollen and leaf waxes that provide clues to ancient temperatures. Scientists have now retrieved samples of pollen and leaf wax from 15.5-million- to 20-million-year-old sediments that indicate Antarctica not only received more rain during the Middle Miocene than previously thought, but was also home to trees, albeit stubby ones. The discovery implies that, contrary to previous thinking, the continent has experienced warm periods since the onset of the most recent glaciation.
Sarah Feakins, a paleoclimatologist and organic geochemist at the University of Southern California who led the recent study published in Nature Geoscience, says that a large ice sheet began to develop on Antarctica 34 million years ago. But scientists have thought that for the most part, the continent has been pretty cold since. Then Sophie Warny, a palynologist at Louisiana State University and co-author of the study, reported in a previous study that she’d found high levels of pollen in Middle Miocene ocean sediment collected near Antarctica. “We were surprised by the species that were there and how much pollen was there,” Feakins says.
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