Tech UPTechnologyWhen Antarctica was a rainforest

When Antarctica was a rainforest


90 million years ago there was tropical vegetation and swamps on the western coast of Antarctica. This was demonstrated by some remains of roots, pollen and spores found on the seabed about 900 kilometers from the south pole. A large concentration of carbon dioxide allowed this environment to exist in this area, which later became the cold climate with which we know it.

an era of heat

The Mesozoic , the age of the dinosaurs, is divided into three periods: Triassic, Jurassic, and Cretaceous. The Cretaceous began about 145 million years ago and ended 66 million years ago, when the mass extinction took place that wiped out most of the dinosaurs. Towards the middle of the Cretaceous there was one of the warmest times on our planet in the last 140 million years . This is a time when the continents were still moving towards the location we recognize today on our maps. One of the questions that science has asked about this situation is: what were the poles like during this very warm period? A 2020 study published in the journal “ Nature ” has the answer.

It has been discussed whether polar ice could have existed at the high temperatures that we know existed during the mid-Cretaceous. Johann P. Klages spearheaded the study of a sedimentary sequence extracted from the West Antarctic Shelf, the southernmost Cretaceous remains collected to date. The results show that a lowland temperate tropical forest environment developed in the area during the Turonian-Santonian era, that is, between 92 and 83 million years ago.

The remains found near the Pine Island and Thwaites glaciers consist of a 3 meter long network of fossilized roots with remains of pollen, spores and flowering plants with an extraordinary level of preservation.

Ulrich Salzmann, paleoecologist at the University of Northumbria, was in charge of studying the pollen and spores to reconstruct the climate and flora that could have existed in the area:

“It was particularly fascinating to see fossil pollen and other plant remains so well preserved in sediment deposited about 90 million years ago near the South Pole. The numerous plant remains indicate that the coast of West Antarctica was, at that time, a dense temperate swamp forest, similar to the forests found in New Zealand today.”

Mild temperatures and lots of rain in Antarctica

The analyzes mark average annual temperatures of about 12 o C less than 1000 kilometers from the south pole. A temperate climate taking into account the long night in this area of our planet, in which the light and heat of the sun do not affect for four months in a row. During the summer periods, it is estimated that the average temperature would be around 19 o C, with the water in rivers and swamps being able to reach 20 o C.

It is incredible to think about other ideas conveyed by the study: 90 million years ago, in West Antarctica there was a similar amount and intensity of rainfall as Wales has today . At that time, the sea level of the entire planet was 170 meters higher than it is today.

Carbon dioxide warmed the planet

This situation was possible due to the extremely high concentration of carbon dioxide (CO2) in the Earth’s atmosphere during the Cretaceous, which had a drastic impact on the average global temperature, making our world a much hotter place than today:

“Before our study, the general assumption was that the global concentration of carbon dioxide in the Cretaceous was about 1,000 parts per million. But in our model-based experiments, the concentration reached levels of 1,120 to 1,680 parts per million, necessary to reach the average temperatures of that moment in Antarctica”.

In order for us to understand the magnitude of these figures, it is enough to know that the global concentration of carbon dioxide was around 416 parts per million in 2021 . Since measurements began in 1959, the atmospheric level of carbon dioxide has steadily increased.

The aforementioned study, in addition to discovering the paleoenvironment of this region of the planet, helps to understand the relationship between the accumulation of CO2 and the climate, reformulating new questions that science will seek to answer: how were these levels of CO2 reached? How did the planet cool down after one of the warmest periods in its history? In these answers and the knowledge provided by research could be a good part of the keys to combat the climate change we are facing.


Klages, J. P. et al. 2020. Temperate rainforests near the South Pole during peak Cretaceous warmth. Nature 580, 81-86. DOI: 10.1038/s41586-020-2148-5.

Nieves, JM 2020. They find the remains of an ancient tropical forest near the South Pole.

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