Over the recent years, wildfires have become increasingly common in various regions of the world due to poor land management practices as well as human activities that trigger climate change. In the U.S., the greatest number of homes threatened by the risks of wildfire is found in South California.
The Last Global Mass Extinction
Almost 13,000 years ago, Southern California experienced a series of wildfires which permanently changed the vegetation of the region and contributed to the largest mass extinction on Earth in over 60 million years. This event, which wiped out most of the large mammals on the planet, happened at the end of the Pleistocene epoch in a time period known as the Ice Age.
The past 66 million years were considered by scientists as the Age of Mammals where the furry animals dominated the planet when the dinosaurs went extinct. Regions such as Eurasia and Americas were teeming with large beasts such as giant bears, woolly mammoths, and dire wolves. Then all of a sudden, the enormous mammals that had characterized global ecosystems disappeared.
For many years, the reason behind this global mass extinctions remains obscure. Experts linked the impact of a warming climate at the end of the last ice age and the rapid increase of human populations. However, fossil records are usually not enough to determine exactly when the large mammal species disappeared in certain regions.
In a new study, a group of scientists investigated the changes that happened in California during the last major extinction event. The team examined the bones of thousands of large mammals found in La Brea Tar Pits in Los Angeles, the richest ice age fossil site in the world. By dating the proteins in these bones using radioactive carbon, scientists got new insight about the ancient ecosystem as well as the time and cause of its collapse.
Archeological records from La Brea Tar Pits and sediment archives from the bottom of nearby Lake Elsinore provide evidence that the extinction was caused by the deadly combination of dramatic climate disruptions and rapid spread of human populations. The effect of this combinations to ice age extinctions can be found elsewhere, but the study found something new. It is assumed that humans set the catalysts for increased wildfires which led to this dramatic transformation.
As California became warmer, its landscape became drier while its forests receded. At La Brea, the populations of herbivores declined probably due to human hunting and habitat loss. The result of the study further suggests that this combination of global warming, drought, herbivore loss, and human-set wildfires had pushed the ecosystem to a tipping point.
READ ALSO : People Cause U.S. Wildfire More Than Nature
Future Implications
Understanding the causes and effects of the Pleistocene extinctions in South California can offer valuable insights about our modern climate and biodiversity crises. The same combination of rising human population, climate change, human-ignited wildfires, and biodiversity loss are happening again today. There are striking similarities between the late ice age megafaunal extinctions and the modern environmental crises.
This means that the ecosystems that we rely on are vulnerable to collapse when exposed to various pressures. What is more alarming, according to scientists, is that the Earth's temperature today rises 10 times faster than it did at the end of Pleistocene epoch, mostly due to burning of fossil fuels. Efforts to reduce carbon emissions, prevent reckless fire ignitions, and preserve the remaining megafauna can help avoid more catastrophic transformation in the future.
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