Antarctica, currently an icy continent, does not support forests. Its harsh environment, characterized by vast ice sheets, minimal precipitation, and prolonged darkness, prevents large woody plants from thriving. However, scientific evidence reveals a dramatic past for this now-frozen land, a time when lush forests covered much of its surface.
Present-Day Antarctic Vegetation
Antarctica is not entirely devoid of plant life. Hardy non-vascular plants have adapted to the continent’s challenging conditions. These include over 100 species of mosses, 25-30 species of liverworts, and approximately 250 species of lichens. These organisms often grow in dense mats in ice-free areas, particularly along coastal regions and the Antarctic Peninsula, where conditions are milder.
Two native flowering plants, Antarctic hair grass (Deschampsia antarctica) and Antarctic pearlwort (Colobanthus quitensis), also grow here. These vascular plants are primarily found in the northern and western parts of the Antarctic Peninsula, the continent’s warmest and wettest region. They survive harsh winters by losing their leaves and enduring freezing temperatures, relying on wind for pollination during the short summer. Recent observations indicate an increase in the coverage of these plant species, particularly mosses, in response to regional warming trends.
A Lush Past: Evidence of Ancient Forests
Millions of years ago, Antarctica was a vastly different place, supporting extensive forests. During the Cretaceous period (145 to 66 million years ago) and into the Eocene epoch (about 55 to 34 million years ago), the continent was much warmer and largely ice-free. Fossil evidence, including wood, leaves, pollen, and spores, proves these ancient forests existed. These remnants have been discovered in rock formations across the continent, even as close as 900 kilometers from the South Pole.
During the mid-Cretaceous, about 90 million years ago, West Antarctica hosted a temperate rainforest, similar to those in New Zealand today. This forest, composed of conifers like podocarps and araucarians, along with ferns and early flowering plants, grew despite a four-month polar night. Later, in the Paleocene and Eocene, forests dominated by Nothofagus (southern beech) trees were prevalent. These forests were diverse, with both evergreen and deciduous species, indicating a cool to warm temperate climate across the continent’s high latitudes.
The Transformation: From Green to White
The shift from a green, forested continent to its current icy state was driven by geological and climatic changes over millions of years. This transformation began with the breakup of the supercontinent Gondwana, which included Antarctica, South America, and Australia. As these landmasses drifted apart, ocean gateways began to open. The widening of the sea between Antarctica and Australia, followed by the separation of South America from the Antarctic Peninsula, was key.
The opening of the Drake Passage, between South America and Antarctica, allowed for the establishment of the Antarctic Circumpolar Current (ACC). This ocean current flows eastward around Antarctica, thermally isolating the continent by preventing warmer ocean waters from reaching its shores. This isolation led to a global cooling trend and the formation of ice sheets. Permanent glaciation began about 34 million years ago, around the Eocene-Oligocene boundary, as atmospheric carbon dioxide levels decreased. While East Antarctica became glaciated first, West Antarctica remained largely ice-free and forested for several million years longer, eventually succumbing to ice as temperatures continued to drop.