Imagine the Chilean Patagonia forests: dense, wet, and cold. monkey puzzle treesConifers, and other hardy conifers. Imagine it with dinosaurs roaming around. You can also light it.
This is what Antarctica was like 75 million years ago during the Cretaceous period, an era known by researchers as a “super fire world.” A paperPublished in Polar Research last month by Flaviana Jorge De Lima of Brazil’s Federal University of Pernambuco along with other scientists from Brazil, the findings show that these conflagrations didn’t spare any continent. Even one that is known for its dry, inhospitable climate as well as its largely deserted landscape.
Although research on prehistoric wildfires — properly called “paleofires” — has been going on for decades, much of it has concentrated on the Northern Hemisphere. Antarctica was “first considered a region without high fires, but that changed,” said André Jasper of the University of Taquari Valley in Brazil. He’s an author on the paper and part of a group of researchers around the globeYou are looking for evidence of fires that occurred between 60 million-300 million years ago.
“It’s really interesting for us because now we’re showing that not only the Northern Hemisphere was burning, but the Southern Hemisphere too,” he said. “It was global.”
Scientists can look at fossilized charcoal molecules and analyze sediment from ancient lakes to find evidence of paleofires. For this paper, the researchers analyzed charcoal extracted from sediment on Antarctica’s James Ross Island in 2015 and 2016.
This charcoal is nothing special.
“If you do a barbecue, you will have the same type of material,” Dr. Jasper said. These chunks measured in at least a quarter of an inch and were several times as large as a quarter. They discovered something more than just the remains of a cookout: homogenized cells, and a pitted pattern which proved that these fossils were ancient plants.
Using the charcoal, “it is possible to understand a little bit better the scenario of the fire, 75 million years ago,” Dr. Jasper said.
Scientists can reconstruct ancient ecosystems with increasing precision using increasingly sophisticated techniques, according to Elisabeth Dietze who is vice president of International Paleofire Network and was not associated with this study. She stated that molecular markers embedded in charcoal could help scientists determine what type of vegetation burned. For instance, rounder, plated molecular forms indicate woody biomass.
In 2010, researchers on King George Island first gathered evidence that ancient wildfires didn’t spare Antarctica. However, the samples taken from that expedition weren’t well preserved. Researchers could only speculate that charcoal came from a coniferous forest. Researchers did a more thorough assessment of these charred remains and concluded that they likely came from an Araucariaceae family, an ancient group of conifers.
The next big question for paleofire researchers is causality. The Cretaceous period was marked in mass extinctions, fluctuations in oxygen levels and changes in the amount or vegetation that covered the planet. These changes were caused by fires or the changes. Understanding this super fire world helps researchers develop models for periods of rapid ecological change and increasing numbers of fires — like now.
“The more we know about the past and the linkages between the ecosystem and climate, the better prepared we are for the future,” said Cathy Whitlock of Montana State University, who was not affiliated with the study.
In some ways the era humans live in can’t compare to the Cretaceous: Back then, our continents, including Antarctica, were still forming. But it’s still notable that high-latitude regions were warm, forested, ice-free and prone to blazes — a direction in which we might be moving.
“Of course, this was millions of years ago, but now we have a driver,” Dr. Jasper said. “We are the driver. Nowadays we have humans putting fire on everything.”
Here’s an example: In 2018, researchers moved these charcoal samples out of the National Museum of Brazil to another laboratory. A few months later, the museum caught fire and the country lost countless relics. These charcoal chunks, which were used to unlock the secrets deep time’s secrets, were almost lost in flames.