Sedimentary rocks raised from the region, which in the Cretaceous period was beyond the Southern Arctic Circle, preserved numerous plant remains, indicating that at that time a dense tropical forest fluttered here.
In the Cretaceous period, the carbon dioxide content in the Earth’s atmosphere was several times greater than the present, and this was one of the warmest eras in the history of life on the planet. A research expedition that visited Antarctica aboard the RV Polarstern in 2017 collected data on what the southernmost continent looked like then, about 90 million years ago.
Numerous seeds and pollen of thermophilic plants were found in samples from the Antarctic region, which in the Cretaceous was located only 900 kilometers from the South Pole. Apparently, at that time it was covered with a humid tropical forest full of diverse life. This Johann Klages (Johann Klages) and his colleagues on the polar expedition PS104 reported in an article published in the journal Nature.
RV Polarstern operated in the Amundsen Sea in western Antarctica, at 73.5° south latitude. Using the remotely controlled MARUM MeBo70 subsea drilling rig, scientists obtained sedimentary rock samples from depths up to 80 meters below the seabed. At a depth of about 30 meters were deposits of the Cretaceous period – the era when this region was located at a latitude of 82 ° and was located above sea level, acting as part of the now-lost continent of Zealand.
It is worth noting that the 80th northern meridian passes above the Arctic Circle, through the Arctic Ocean. However, in samples from the southern sea, researchers identified petrified pollen particles and seeds of at least 62 species of ancient plants, as well as fragments of petrified root systems. They testify that in that distant era in these polar latitudes a dense forest fluttered, similar to those that exist today in New Zealand.
Klage and his co-authors modeled the climate of this region during the Cretaceous, calculating that the average annual temperature here was not so high – about 13 ° С. However, for an area where the polar night lasts four months a year, this is very unexpected. According to scientists, in order to maintain such a temperature here, the content of greenhouse carbon dioxide in the Earth’s atmosphere should have been about 1120-1680 parts per million (ppm) – against modern 415 ppm.