Little else but ice, snow, and penguins likely pops into your head when you can spare a thought for Antarctic. But there's much more to the continent than meets the eye, as scientists describe in Nature. Analyzing a sediment core taken from the seafloor of West Antarctica's Amundsen Sea, they found well-preserved samples of clay and silt soil, root systems, spores, and pollen, indicating Antarctica was home to a rainforest about 90 million years ago. The core—the southernmost sample of the Cretaceous period ever collected, per CNN—shows evidence of 65 different kinds of plants. At the time, the average daytime temperature was 53 degrees, far warmer than the current range of -76 degrees to 14 degrees, per the Guardian. Even then, however, the sun didn't shine for four-month stretches.
"Even during months of darkness, swampy temperate rainforests were able to grow close to the South Pole, revealing an even warmer climate than we expected," says study co-author Tina van de Flierdt. Scientists believe the rainforest, fed by annual rainfall comparable to that now seen in Wales, grew without constant sunlight because of the warming effect of atmospheric carbon dioxide, which existed in higher concentrations than expected. "We didn't know that this Cretaceous greenhouse climate was that extreme," co-author Johann Klages tells the Guardian. "It shows us what carbon dioxide is able to do." Geochemist James Bendle explains there could be similar levels of carbon dioxide on Earth by 2100. "If we have an atmosphere of more than 1,000 parts per million of carbon dioxide, we are committing ourselves to a future planet that has little to no ice," he says. (Read more discoveries stories.)