Wildfires leading to extinction? Palaeontologists investigate

Are we headed towards another extinction event similar to what the dinosaurs faced? Is there a pattern emerging? A recent study draws parallels.
Amal Jos Chacko
The fossil deposits at the La Brea Tar Pits in Los Angeles have well-preserved remains of many prehistoric animals that got stuck in natural asphalt seeps over the past 60,000 years
The fossil deposits at the La Brea Tar Pits in Los Angeles have well-preserved remains of many prehistoric animals that got stuck in natural asphalt seeps over the past 60,000 years

National History Museums of Los Angeles County/ Cullen Townsend 

The past decade has seen a rise in the frequency and intensity of wildfires, presenting a global environmental challenge driven by both climate change and human activity. 

Southern California, a region already prone to devastating fires, has witnessed the convergence of these factors, but this is not the first time flames have left their mark. 

In a recent study published in the journal Science, paleontologists delve into the annals of history, uncovering a shocking revelation about the fires that decimated Southern California's megafauna around 13,000 years ago.

Wildfires leading to extinction? Palaeontologists investigate
An illustration of moist and cool around the tar pits, with abundant trees and megafaunal mammals.

Echoes of extinction

The story of Southern California's ancient megafauna unfolds within the La Brea Tar Pits, an active paleontological research site in Los Angeles that captures the past within its naturally occurring bubbling asphalt. 

The Pleistocene, the geological epoch more commonly known as the Ice Age, was one where large beasts such as wooly mammoths, giant bears, and dire wolves roamed and flourished.

Then they disappeared.

“It was the biggest extinction event since an asteroid slammed into Earth and wiped out all the dinosaurs,” Emily Lindsey, a paleoecologist and author of the new study told The New York Times.

Although researchers have long debated the causes behind the megafaunal extinction, a combination of climate change and human influence have taken center stage as the driving factors. 

Rising temperatures, drought, and the expansion of human populations collided to set off a series of unprecedented wildfires that forever transformed the ecosystem.

The bubbling asphalt seeping to the surface of the Earth from within is a treasure trove for the fossils of prehistoric animals that got stuck in it and died.

The team analyzed climate and fire records in the region and compared them against human population growth across the timeline.

They observed that the rise in human occupation aligned with the happening of droughts and fires. The once rich-in-juniper-and-oak-trees vegetation came to be replaced by grass and shrubs.

The team of scientists used a prediction model to determine if humans were the primary culprits behind this 400-year-long period of wildfires. 

Although the pattern observed does not account for the disappearance of prehistoric animals anywhere else in the world, Regan Dunn, a paleobotanist and one of the authors of the study, underlined the need to look at a regional scale to understand its global impact. 

Lessons from the past to save the future

The study draws parallels between the past and the present and casts a stark light on the current challenges of climate change and loss of biodiversity. 

As temperatures rise, fires intensify, and habitats transform, the eerie resemblance between the environmental crisis of today and the ancient extinction episode is impossible to ignore. The research team underscores the urgent need to address the intersection of human activity and changing ecosystems to prevent catastrophic consequences. 

While the past may offer alarming lessons, it also provides a glimmer of hope – the realization that human intervention can alter the course of history, allowing us to avert a repeat of the devastating events of the past.

In an era where climate change and human activity stand as potent threats to the world's ecosystems, the past beckons us to heed its lessons.

Study Abstract

The cause, or causes, of the Pleistocene megafaunal extinctions have been difficult to establish, in part because poor spatiotemporal resolution in the fossil record hinders alignment of species disappearances with archeological and environmental data. We obtained 172 new radiocarbon dates on megafauna from Rancho La Brea in California spanning 15.6 to 10.0 thousand calendar years before present (ka). Seven species of extinct megafauna disappeared by 12.9 ka, before the onset of the Younger Dryas. Comparison with high-resolution regional datasets revealed that these disappearances coincided with an ecological state shift that followed aridification and vegetation changes during the Bølling-Allerød (14.69 to 12.89 ka). Time-series modeling implicates large-scale fires as the primary cause of the extirpations, and the catalyst of this state shift may have been mounting human impacts in a drying, warming, and increasingly fire-prone ecosystem.

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