What role did forest fires play in the worst disaster ever? Scientists have tried to clarify this by looking at charcoal residues.

About 252 million years ago, the largest mass extinction in Earth’s history took place: the Permian-Triassic or PT extinction. Among other things, 81 percent of marine species died, as well as 70 percent of terrestrial vertebrates. Exactly how that disaster happened has been the subject of research for years.

Now do paleontologist Chris Mays from University College Cork in Ireland and Stephen McLoughlin from the Swedish Museum of Natural History in Stockholm a penny in the bag. In a new study they are trying to clarify the role that forest fires played at the time.

Acid rain and metal poisoning

The most accepted cause of the PT extinction was eruptions of the Siberian Steps, a volcanic plain in present-day Siberia. They would have pumped large amounts of carbon dioxide into the air. This subsequently led not only to higher temperatures worldwide, but also to, among other things, ozone depletion, acid rain and heavy metal poisoning. With all the consequences that entails for earthly life.

The eruptions also fueled forest fires. But, Mays and McLoughlin wonder, what exactly were the effects of those wildfires?

Still fatal

For their study, Mays and McLoughlin looked at charcoal remains in eastern Australia and eastern Antarctica. On the one hand, they show that wetlands in the southern supercontinent Gondwana were regularly confronted with forest fires before the PT extinction. The plants had learned to deal with this in different ways, or so the idea is.

However, around the PT extinction, the frequency of fires skyrocketed. As a result, the plants in the Gondwanan (?) wetlands had to clear the field. “And that may have played a key role in the collapse of terrestrial ecosystems during the PT extinction,” Mays and McLouglin write. In addition, those fires will have emitted additional greenhouse gases that exacerbated the climate change initiated by the Siberian Steps.

After the extinction, at the beginning of the next epoch, the Triassic, the number of fires was very low for millions of years, as the amount of coal shows. “Based on this, the researchers conclude that a lot of biomass must have been burned around the time of extinction, resulting in less vegetation and therefore fewer fires,” said Dennis Voeten, vertebrate curator at Uppsala University’s Museum of Evolution.

Puzzle

biogeochemist Martin Schobben of Utrecht University calls the study “very solid and intriguing”. Among other things, he thinks it is strong that Mays and McLoughlin have looked at small, medium and large charcoal particles.

Voeten also thinks the research is thorough. He does note that the link between the PT extinction and forest fires has already been found before. “But it’s always good to have that kind of information available from multiple locations.”

According to Voeten, however, more original approaches are needed to really get a clear picture of what exactly happened 252 million years ago. Moreover, this requires “information from a multitude of sources and disciplines”. “Only then will the puzzle of the PT extinction be solved in the future.”

Lesson for the present

Mays sees a lesson in the research for the present. Current climate change is also leading to an increase in droughts and wildfires in areas that are normally quite wet – and where a lot of carbon is stored. “Unlike the species that suffered mass extinctions in the past, we have a chance to prevent the depletion of those carbon stores, thus avoiding the worst effects of current warming,” Mays said in a statement. press release†