Many people think that the cataclysmic event that wiped out the dinosaurs was the biggest in the history of our planet. Contrary to that popular opinion, the biggest mass extinction event took place around 252 million years ago, and the main culprit was climate change. According to a new study, the event took place after a series of destructive volcanic eruptions in Siberia.
Scientists studied a thriving marine ecosystem and the ancient seafloor rocks that surrounded it. A team of scientists found that 96 percent of marine species in the ecosystems were wiped out during the event of the “Great Dying.”
The team of researchers from the University of Washington and Stanford University created models of the ocean conditions for that time period and combined it in a study which was published in the journal Science. The biggest mass extinction event was caused by global warming. It caused the sea temperature to rise which caused higher metabolic rates in marine animals, which resulted in them not having enough oxygen to survive.
“This is the first time that we have made a mechanistic prediction about what caused the extinction that can be directly tested with the fossil record, which then allows us to make predictions about the causes of extinction in the future,” said first author Justin Penn, a UW doctoral student in oceanography in a statement.
The team created a climate model of how Earth looked like in the Permian times. At that time, the land masses were creating the ancient continent Pangaea, when the climate change started.
At that time, the global continent’s temperature was similar to how we have it today, but then volcanic eruptions coming from Siberia changed everything. The eruptions were so massive that they created a complete greenhouse-gas planet out of Earth. To replicate such an event, the researchers had to do the same in their model, by increasing the temperature of the ocean at the surface around 20 degrees Fahrenheit. The rise in temperature caused drastic changes in the climate, causing the ocean to lose 80% of its oxygen. The ocean floor was practically without any oxygen.
The model showed that organisms which were sensitive to oxygen the most, suffered the most, especially far from the tropics. The model shows that many animal species which were adjusted to a tropical climate also went extinct.
The team needed to test the model in real time, so co-authors of the study, Jonathan Payne and Erik Sperling from Stanford University studied the late-Permian fossil samples from the Paleoceanography Database which features a virtual collection of published fossils. Those records show the location of the species before they were wiped out and more. The fossil record showed that animals farthest from the equator suffered the most when the biggest mass extinction event occurred.
“The signature of that kill mechanism, climate warming, and oxygen loss, is this geographic pattern that’s predicted by the model and then discovered in the fossils,” Penn said. “The agreement between the two indicates this mechanism of climate warming and oxygen loss was a primary cause of the extinction.”