It is hard to believe, but once Antarctica was a green, tropical paradise with furry mammals like possums and beavers. Scientists say that it is only in the quite recent geological past it got so cold there. Around 52 million years ago, the concentration of carbon dioxide (CO2 or the greenhouse gas) was more than twice as high compared to today and the climate was much hotter. However, according to scientists, if the current CO2 emissions continue to rise due to burning of fossil fuels, the amount of greenhouse gas in the atmosphere that existed millions of years ago is likely to be achieved within a few hundred years.