Antarctica Was Once a Lush Green Rainforest — Scientists Finally Figured Out What Happened To It

Antarctica, by its mere existence, regulates the global climate with its vast ice sheet reflecting most of the sunlight it receives back into space. But about 90 million years ago, the icy continent characteristic of the South Pole was a green landmass of swampy rainforest with soaring sea levels, new evidence suggests, as reported by CNN. This was a time when dinosaurs existed and Earth’s climate was warmer, which may be credited to an ice-free Antarctica’s teeming flora and fauna as sediment core samples uncovered the unimaginable. 

Researchers excavated the sea floor of the Amundsen Sea in West Antarctica and conducted CT scans on the sediment core samples between February and March 2017. The study published in Nature revealed that sea levels were 558 higher than today during the mid-Cretaceous era– the warmest period of Earth between 80 and 115 million years ago. Moreover, the surface temperature of the planet shot up to 95 degrees Fahrenheit in the tropics. 

Meanwhile, the sediment cores taken near the Pine Island and Thwaites glaciers revealed samples of forest soil, pollen, spores, and root system, indicating that the snow-clad continent was once green enough to sustain forest life, as concluded by the scientists. Geologist and lead author Johann Klages noted that the atypical coloration of the sediment layer piqued their interest. “During the initial shipboard assessments, the unusual coloration of the sediment layer quickly caught our attention; it clearly differed from the layers above it,” he said. He suggested that the layer was originally formed on land and further analysis revealed it dated back to 90 million years ago. 

The study described the well-preserved conditions of the forest residue in the ancient samples which liberated Alfred Wegener Institute experts to identify cell structures and pollen of the first plants thriving in Antarctica. The samples collected are the first of its kind and the southernmost sample of soil ever collected that hints at the conditions about 93  million years ago. Noting the prolonged preservation of the forest samples, Tina van de Flierdt of the Imperial College London’s Department of Earth Science and Engineering, and a co-author of the study, marveled at the intriguing world that once thrived in Antarctica, as the evidence suggested. 

“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,” she explained. However, there were still doubts about the forests surviving Antarctica’s four-month polar night. Further research on the carbon dioxide levels during the Cretaceous era revealed that the high CO2 concentrations maintained the warm climates at the South Pole preventing ice formation, explained Torsten Blickert, co-author and geologist at the University of Bremen’s BARUM research center. 

To think of it, the sky-high sea levels in that era when Antarctica was free of ice is imaginable, and simultaneously, the fairly lower global temperatures in modern times. The South Polar continent bears witness to a key natural process, called the ice-albedo effect, which prevents the planet from absorbing excessive solar heat as the ice sheets act as giant mirrors to regulate the climate, per the NIWA. In the absence of it, the world could be uninhabitable or result in the evolution of different life species that thrive in warmer temperatures. Nevertheless, human activity seems to be heading in that direction with uncontrolled CO2 emissions causing sea levels to rise at alarming rates.