Scientists drilling deep into the edge of modern Antarctica have pulled up proof that palm trees once grew there. Analyses of pollen and spores and the remains of tiny creatures have given a climatic picture of the early Eocene period, about 53 million years ago. The study in Nature suggests Antarctic winter temperatures exceeded 10C, while summers may have reached 25C. better knowledge of past "greenhouse" conditions will enhance guesses about the effects of increasing CO2 today. The early Eocene - often referred to as the Eocene greenhouse - has been a subject of increasing interest in recent years as a "warm analogue" of the current Earth. "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