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Imagine the Chilean Patagonian forests: wet and cold, dense monkey puzzle trees and other hardy conifers. Now imagine with dinosaurs walking around. And it’s burning.
Such was Antarctica 75 million years ago, during the Cretaceous period, known to researchers as the “super fire world.” Paper The paper, published last month in Polar Research by Flaviana Jorge de Lima of the Federal University of Pernambuco and other scientists in Brazil, proves that these fires did not save any continent, not even one today famous for its dry, uninhabitable climate and largely vegetation-free landscape. . .
While research on prehistoric wildfires—properly called “paleofires”—has been going on for decades, most of them have concentrated on the Northern Hemisphere. André Jasper, of the University of Taquari Valley in Brazil, said Antarctica was “first considered a region without high fires, but that has changed”. He is a writer and a piece of paper a worldwide group of researchers It’s looking for evidence of fires that burned between 60 million and 300 million years ago.
“It’s really interesting for us because now we show that not only the Northern Hemisphere is burning, but the Southern Hemisphere as well,” he said. “It was global.”
Scientists can find evidence of paleofires by examining charred tree rings, by analyzing sediments in ancient lakes or by examining molecules in fossilized coal. For this article, researchers analyzed coal mined from sediment on Antarctica’s James Ross Island in 2015 and 2016.
This charcoal is nothing special on the face.
Dr. “If you barbecue, you’re going to have the same kind of ingredients,” Jasper said. But the team used imaging software and scanning electron microscopy to analyze these bright fragments, which are about a quarter high and several times as wide. They found something much more interesting than the remains of an oven: homogenized cells and a seedless pattern that proves these fossils began their lives as ancient plants.
Dr. “It’s possible to understand a little better the scenario of the fire 75 million years ago,” Jasper said, using coal.
Elisabeth Dietze, vice president of the International Paleofire Network, said that with increasingly sophisticated techniques unrelated to research, scientists can reconstruct ancient ecosystems and fire patterns with assembly precision. He said molecular markers in coal can tell scientists what type of vegetation is burning: For example, more rounded, coated molecular shapes indicate woody biomass.
In 2010, researchers on King George Island gathered evidence that ancient wildfires did not save Antarctica. But samples from this expedition were poorly preserved, and the researchers could only guess that the coal came from a coniferous tree. The researchers made a more accurate assessment of these newly charred remains: They suspect they came from an ancient family of conifers, the Araucariaceae.
For Paleofire researchers, the next big question about these ancient fires is about causation. The Cretaceous period was marked by mass extinctions, fluctuating amounts of oxygen in the atmosphere, and changes in the amount of vegetation covering the planet. Did the fires cause these changes, or did the changes cause the fires? Understanding this superfire world helps researchers develop models for periods of rapid ecological change and increasing numbers of fires – like the present.
“The more we know about the past and the links between ecosystem and climate, the better we are prepared for the future,” said Cathy Whitlock of Montana State University, who was not involved in the study.
In some ways, the era in which humans lived cannot be compared to the Cretaceous: At that time our continents, including Antarctica, were still forming. But it’s still notable that high-latitude regions are hot, forested, ice-free and flame-prone – we may be moving in that direction.
Dr. “Of course, that was millions of years ago, but now we have a driver,” said Jasper. “We are the drivers. Today we have people who set everything on fire.”
Case in point: In 2018, researchers moved these charcoal samples from the Brazilian National Museum to a different lab. Few months later, the museum caught fire and the country lost countless relics. These ancient pieces of coal, used to unravel the secrets of deep time, were almost lost in the flames.
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