Imagine a great, green rainforest thriving inside the icy land that exists today. It might sound like science fiction, but research shows that Antarctica was once warm enough to host temperate rainforests near the South Pole about 90 million years ago. A scientific study published in PubMed Central, titled “Temperate rainforests near the South Pole during peak Cretaceous warmth”, analyzed fossil soil, roots, pollen, and spores extracted from deep beneath the seafloor near West Antarctica. Surprisingly, the findings show a remarkably warm climate during the Cretaceous period, a time when dinosaurs roamed Earth and carbon dioxide levels were much higher than today. This rainforest ecosystem probably included conifers, ferns, and flowering plants, while the average annual temperature was more like that of modern regions such as parts of Australia or Wales, far removed from the frozen continent we know today.
How did scientists find evidence of an ancient rainforest in Antarctica
Experts excavated the seafloor near West Antarctica and unearthed ancient soil layers that were part of a living forest. Experts were able to carry out further studies with the fossilized roots, pollen, and spores within the excavated area. They were able to paint a vivid picture of the vegetation within an area less than 1,000 kilometers from the South Pole. Experts are not able to carry out such a study very often since the materials are very delicate and are likely to decay with the passage of time.
What Was the Climate Like 90 Million Years Ago
At that time, Earth’s climate was in the midst of the Cretaceous greenhouse, representing the Earth’s warmest climate over the last 140 million years.The average temperature over the 12 months of the year in the area near the South Pole in Antarctica was perhaps 12 degrees C. The average temperature during the summer might have risen to around 19 degrees C to 20 degrees C, and rainfall similar to that prevailing today over Wales. Remarkably, these conditions existed despite long polar nights with months of darkness each year, when sunlight was limited.
Why was Antarctica so warm back then?
That wasn’t mystery magic; it’s tied to Earth’s ancient climate and to greenhouse gases. The study estimates that atmospheric CO₂ in the Cretaceous was substantially higher than previously believed. Elevated CO₂ levels with the absence of large ice sheets enabled temperate forests to exist well toward the pole. In contrast, today’s Antarctic is dominated by thick ice and frigid temperatures because carbon dioxide concentrations are much lower and the climate has cooled a lot.
What did that rainforest look like?
The ancient Antarctic landscape would have been a swampy temperate forest teeming with various forms of plant life. An abundance of fossils found from conifers, ferns, and flowering plants led them to conclude that a complex ecosystem like those from the modern temperate zones of New Zealand must have graced the continent. Fossilized roots embedded in the soil reflect a dense network of vegetation that once blanketed the land.
Why this discovery matters for our understanding of climate change
By researching and learning from the different climatic changes on our own planet, scientists have been able to learn how various natural factors help to affect changes to the environment over huge periods of time. Furthermore, the fact that there was previously a rainforest at such high latitude is proof of how warm our planet is capable of getting when the greenhouse gases are this high. It is not an exact science predicting our future, but instead, an important piece in understanding how CO₂ is capable of controlling our environment’s overall temperature.
