US, WASHINGTON (ORDO NEWS) — Even when Antarctica was already at the South Pole, dense rainforests grew on its territory. The incredible find of paleontologists convinces of this.
The discovery is described in a scientific article published in the journal Nature.
The continents, as you know, do not stand still . But 80-90 million years ago, Antarctica was already in the polar latitudes. However, does this mean that it was covered in ice? Not at all. Numerous finds show that forests were growing on the continent at this time.
The fact is that the middle of the Cretaceous period was one of the warmest eras in the history of the Earth over the past 140 million years. The carbon dioxide content in the atmosphere was much higher than today, which ensured a noticeable greenhouse effect.
In addition, the location of the continents still allowed ocean currents to effectively transfer heat from the equator to the poles. As a result, the difference in climate between the tropics and the Arctic was not as dramatic as today, when this “distribution system” was destroyed.
Nevertheless, the new find surprised even experts who are well versed in the history of the planet. It shows that the ancient polar landscape was not just temperate forests, but temperate rainforests. This means that the climate of the present ice continent was then not just temperate (which is not news), but much warmer than previously thought. This poses new challenges for climatologists.
A paleosol sample taken on the west coast of Antarctica in 2017 is 93-83 million years old. At this time, this land area was at a latitude of 82 degrees. In other words, it lay far beyond the southern polar circle, only 900 kilometers from the pole.
However, the researchers found in it an extensive network of roots up to three meters long. In addition, in it they found a variety of pollen and spores. Scientists managed to consider even the fine structure of the soil. Its basis was fine-grained clay or silt.
“Numerous plant debris suggests that 93-83 million years ago, the coast of West Antarctica was a marshy landscape with temperate rainforests, similar to forests that can still be found, say, on the South Island of New Zealand,” says co-author of the article Ulrich Salzmann ( Ulrich Salzmann ) from the University of Northumbria in the UK.
Among other things, the sample contains the first remains of flowering plants ever discovered in such high paleolatitudes.
How warm and humid was it on the continent then? In answering this question, experts focused on what climate determines the existence of a modern flora of this type. In addition, they used geochemical features to reconstruct the climate of those distant times.
Several different methods eventually led to the same result. The average annual air temperature was about 12 degrees Celsius. At the same time, the average summer air temperature reached 19 degrees. The water in the rivers and swamps at the same time warmed up to 20 degrees. About a thousand millimeters of precipitation fell during the year. In Russia, only Sochi or the Kuril Islands can boast of a wetter climate.
Under what conditions was such a warm and humid climate possible at a latitude of 82 degrees? To understand this, the researchers conducted a simulation.
It turned out that at that time even at the South Pole there could not have been glaciation (otherwise it would have been much colder, since the ice reflects sunlight well). Moreover, the continent had to be completely covered with dense forests. But the main thing – I had to seriously review the carbon dioxide content in the air.
It was previously believed that in that era, the concentration of CO 2 in the Earth’s atmosphere was 1000 parts per million by volume. (For comparison: today, despite the not very reasonable behavior of a rational person , it barely exceeds 440 parts per million). But modeling showed that it was significantly higher: from 1120 to 1680 parts per million.
Now independent climatologists have to verify these calculations. And, if they are confirmed, it is necessary to embed a new idea of the Cretaceous climate in the overall picture. In addition, it is necessary to answer the question of how such a warm Antarctica quickly (by geological standards) covered itself with an ice sheet.
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