According to a paper published in Nature, Antarctica was not always a frozen tundra. Millions of years ago, it was a temperate rainforest, even during times of the year where no light shined down on the region at all.
The researchers discovered this fascinating fact after drilling into the seafloor and discovering the fossilized remnants of roots, pollen, and spores preserved in the mudstone of the west Antarctic shelf. The samples were amazingly preserved, allowing researchers to study the individual ceels and their structures.
The samples originally came to the scientist's attention due to their unique coloration. “It clearly differed from the layers above it. Moreover, the first analyses indicated that, at a depth of 27 to 30 meters [88.5 to 98 feet] below the ocean floor, we had found a layer originally formed on land, not in the ocean,” Johann Klages, one of the study authors, said in a press release.
The samples point to similarities in other rainforest environments still active around the world. After study and comparison, the study finds similarities with “numerous plant remains…the coast of west Antarctica was a swampy landscape in which temperate rainforests grew—similar to the forests that can still be found…on New Zealand’s South Island.”
So the big question is, how can an environment where the sun doesn't shine for months at a time keep a temperate rainforest healthy? Well, the CO2 in the atmosphere was much higher, keeping the environment hotter.
“We now know that there could easily be four straight months without sunlight in the Cretaceous; the [CO2] concentration was so high, the climate around the South Pole was nevertheless temperate, without ice masses,” says Torsten Bickert, paper author and geoscientist.
So with that solved, the question remains; what turned Antarctica from a rainforest to a frozen tundra.