Fossilized finds from 90 million year old rainforest discovered under Antarctic ice

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The fossilized remains of an “unexpected” temperate rainforest that developed 90 million years ago in western Antarctica have been discovered by scientists.

Analysis of sediment cores collected from the western Antarctic shelf revealed forest soils, roots, pollen and spores, indicating that the continent had an “exceptionally hot climate” in the middle of the Cretaceous when the dinosaurs roamed. Earth.

The international team of scientists said the Antarctic rainforest would have looked like the forests of New Zealand today.

The Middle Cretaceous was the hottest period in the past 140 million years. Sea level was 170 meters higher than today and sea surface temperatures in the tropics are said to have reached 35 degrees Celsius.

Until now, little has been known about the environmental conditions south of the Arctic Circle, scientists said.

Artist’s impression of the appearance of West Antarctica 70 million years ago in the Cretaceous

The evidence for the Antarctic rainforest comes from a core of sediment collected from the seabed near the western glacier of Pine Island to the west of the continent in 2017.

“During the initial assessments aboard the ship, the unusual coloring of the sediment layer quickly caught our attention; it clearly differed from the upper layers, “said the study’s first author, Dr. Johann Klages, a geologist at the Helmholtz Center at the Alfred Wegener Institute for Polar and Marine Research in Germany.

The team scanned the core of the sediment and discovered what it described as “a dense and fascinating network of roots spreading across the entire layer of soil.”

They said the 90 million-year-old soil is so well preserved that it contains countless traces of pollen, spores, remnants of flowering plants, and that researchers could even distinguish individual cell structures.

Co-author Professor Ulrich Salzmann, a paleoecologist at the University of Northumbria in the United Kingdom, used pollen and preserved spores to reconstruct past vegetation and climate.

He said that the process of reconstructing past environments and climates was similar to working on a huge puzzle, which ultimately revealed an incredibly detailed picture of the past Antarctic landscape.

“It was particularly fascinating to see the various fossil pollens and other plant remains well preserved in a sediment deposited about 90 million years ago, near the South Pole,” he said.

“The numerous plant remains indicate that the coast of West Antarctica was, at the time, a dense temperate and swampy forest, similar to the forests found in New Zealand today. “

When they gathered their analyzes, the international research team found evidence of a mild climate about 500 miles from the South Pole, with average annual air temperatures of around 12 ° C.

Summer temperatures averaged 19 ° C and water temperatures in rivers and marshes reached up to 20 ° C. This was despite a polar night of four months, which means that for a third every year there was no life giving sun at all. They also found that the amount and intensity of precipitation in western Antarctica was similar to that in Wales today.

Scientists said such climatic conditions could only be achieved with dense plant cover on the Antarctic continent and the absence of major ice caps in the South Pole region.

Research also found that the concentration of carbon dioxide in the atmosphere was also much higher than previously estimated.

Co-author, climate modeler, Professor Gerrit Lohmann, of the German Alfred Wegener Institute, said: “Before our study, the general assumption was that the global concentration of carbon dioxide in the Cretaceous was about 1000 ppm [parts per million.] But in our model-based experiments, it took concentration levels from 1120 to 1680 ppm to reach average temperatures at the time in Antarctica. “

As such, the study shows both the enormous power of carbon dioxide from greenhouse gases and how essential the cooling effects of today’s ice caps are, the team said. .

The study will inform scientists who are struggling to understand what has caused the climate to cool dramatically, which has resulted in the formation of the ice caps we see today.

The research was published in the journal Nature.

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