Environment

Ancient Antarctica was a warm swampy rainforest, says sediment study

Ancient Antarctica was a warm ...
An artist's rendering of West Antarctica, which would have been a swampy forest around 90 million years ago
An artist's rendering of West Antarctica, which would have been a swampy forest around 90 million years ago
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An artist's rendering of West Antarctica, which would have been a swampy forest around 90 million years ago
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An artist's rendering of West Antarctica, which would have been a swampy forest around 90 million years ago
A basic map of the South Pole region at the time of the sediment core, around 90 million years ago
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A basic map of the South Pole region at the time of the sediment core, around 90 million years ago
The control room of the drill rig
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The control room of the drill rig
The lab onboard the RV Polarstern
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The lab onboard the RV Polarstern
The RV Polarstern alongside a massive glacier, off the coast of West Antarctica
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The RV Polarstern alongside a massive glacier, off the coast of West Antarctica
Researchers in the lab onboard the RV Polarstern ship
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Researchers in the lab onboard the RV Polarstern ship
Researchers Tina van de Flierdt (left) and Johann P. Klages (right), examine sediment cores
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Researchers Tina van de Flierdt (left) and Johann P. Klages (right), examine sediment cores
The seafloor drill rig, onboard the RV Polarstern
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The seafloor drill rig, onboard the RV Polarstern
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It’s hard to imagine Antarctica as anything other than a freezing lifeless landscape, but that wasn’t always the case. Now, an international team has recovered a 90-million-year old soil sample that paints the most detailed picture of ancient Antarctica ever found, revealing a swampy rainforest and balmy temperatures.

According to the study, during the peak of the Age of the Dinosaurs, West Antarctica was covered in dense vegetation, rivers and swamps. The annual average air temperature was around 12 °C (53.6 °F), and during summer that average went up to a pleasant 19 °C (66.2 °F). Rainfall amounts and intensity were similar to the lowlands of places like Wales.

The researchers made this startling discovery by studying a sediment core drilled from deep beneath the ocean floor, in the Amundsen Sea off the west coast of Antarctica. A certain section appeared to be extremely well-preserved forest soil.

“During the initial shipboard assessments, the unusual coloration of the sediment layer quickly caught our attention; it clearly differed from the layers above it,” says Johann Klages, first author of the study. “Moreover, the first analyses indicated that, at a depth of 27 to 30 m (88.6 to 98.4 ft) below the ocean floor, we had found a layer originally formed on land, not in the ocean.”

The RV Polarstern alongside a massive glacier, off the coast of West Antarctica
The RV Polarstern alongside a massive glacier, off the coast of West Antarctica

When they studied this layer with X-ray CT scans, the researchers found a remarkably intact sample of an ancient forest floor. The soil was made up of fine-grained silt and clay, with individual cell structures visible. Pollen and spores from plants were found throughout, including the first evidence of flowering plants in Antarctica. And most impressively, a network of tree roots twisted their way through the whole sample.

“The numerous plant remains indicate that 93 to 83 million years ago the coast of West Antarctica was a swampy landscape in which temperate rainforests grew – similar to the forests that can still be found, say, on New Zealand’s South Island,” says Ulrich Salzmann, co-author of the study.

From this picture of what plants covered Mid-Cretaceous West Antarctica, the team then calculated what the climate was like in the area at the time. Along with assumptions based on conditions that similar plants grow in now, the team searched for indicators of temperature and rainfall in the soil.

Researchers Tina van de Flierdt (left) and Johann P. Klages (right), examine sediment cores
Researchers Tina van de Flierdt (left) and Johann P. Klages (right), examine sediment cores

But how did such a pleasant climate come about so far south? Next, the team punched those parameters into a climate model to see what conditions were needed to sustain that kind of temperature and precipitation.

According to their calculations, the whole Antarctic continent must have been covered in vegetation, there had to be no ice sheets at all, and the carbon dioxide concentration had to be much higher than previously thought for the time.

“Before our study, the general assumption was that the global carbon dioxide concentration in the Cretaceous was roughly 1,000 parts per million (ppm),” says Gerrit Lohmann, co-author of the study. “But in our model-based experiments, it took concentration levels of 1,120 to 1,680 ppm to reach the average temperatures back then in the Antarctic.”

This finding has several implications. For one, scientists may have to revisit their Cretaceous-era climate models. It also raises the question of how the climate cooled to create the Antarctica we know today.

The research was published in the journal Nature.

Source: Alfred Wegener Institute

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18 comments
Al
Hi , this is astounding news to me as I have always deep down believed this to be true . Must have been that asteroid strike that shifted the earth axis/poles!!!
orlando30
Fascinating! Could it also be that our understanding of plate tectonics is flawed, and perhaps Antarctica was located further north 90 millions years ago?
PG
Hi. Or, maybe, it's the result of continental drift

https://youtu.be/uLahVJNnoZ4
paul314
Continental drift says the area would have been a similar latitude to the bottom of south america, which is not that warm now. Hope that's not what we're heading for.
clay
Perhaps the Dinosaurs chose to ignore the signs, causing MASSIVE global...oh wait, it's covered in ice now. nvrmnd.
bwana4swahili
“But in our model-based experiments, it took (CO2) concentration levels of 1,120 to 1,680 ppm to reach the average temperatures back then in the Antarctic.”

And the Antarctic climate will get to those conditions again as CO2 levels continue to increase. Looking forward to a lush green Earth, similar to that present in the Cretaceous era. Just don't buy ocean front property!!
Spikev
Many scientists have known for years that it was tropical from ice cores taken of tropical trees.
Many also knew that atmosphere pressure and carbon dioxide was greater...
The climate change also was known...
When the earth split open, the weight of the continents sent vast amounts of water into space.
This super cooled ice particles were attracted mostly to the poles.
Oh yeah-- that would give too much credence to world wide flood, explain mixture of fosiles, water sorting by density, and it would not help the theories of evolution. Ok, we will have to ignore these facts.
Well any other theories?

buzzclick
If these newly-discovered facts are true, then it can only be concluded that the Earth's rotation axis was different. The orientation of the sun (and the moon) to our planet enormously affects the terrestrial conditions. As one of the posters said, a huge asteroid may have shifted things over. The one that wiped out the dinosaurs (and lots of other lifeforms) about 60-70 million years ago may have changed the axis to what we have today.
Damar
At last! Worth checking out Graham Hancock's 1995 book, Fingerprints of the Gods. Good theory about an outer shell of the earths crust that has moved over time. He connects this to the Noah flood stories that seem to be consistent in a variety of cultures.
ljaques
That's AMAZING! Imagine, a climate model which was =not= precisely right all the way through! The answer to that last question is Mother Nature's little Ice Ages. (Hint: This will be on the test.)