The greatest mass extinction on Earth was caused by massive CO2 emissions and the resulting climate change which caused bacteria and algae to flourish in the water. Doesn’t that sound familiar? The same thing could be happening now.
The Earth has already experienced five mass extinctions. These were characterized by the disappearance of at least 75% of our planet’s animal and plant species. Either on land or at the bottom of the oceans. The most important of these was the Permian-Triassic, which occurred about 250 million years ago. During this time, volcanic emissions of greenhouse gases changed the climate of our planet. The level of carbon dioxide (CO2) in the Earth’s atmosphere rose 13-fold! The average temperature has increased from 77°F to 104°F (25°C to 40°C). About 95% of marine life and 70% of land life disappeared as a result.
Scientists at the University of Connecticut have now said that in parallel with these changes in climate, bacteria and algae have multiplied in the waters over hundreds of thousands of years. When these microorganisms become too abundant, they consume the oxygen in the water and even release toxins, and as a result, played an important role in the extinction of oxygen dependant species.
Analysis of fossils, sediment, and chemical data from rocks near Sydney (Australia) shows that the first outbreaks of these microbes occurred at the beginning of the volcanic eruptions that are thought to be the main cause of the Permian-Triassic mass extinction. Because once the animals that fed on them disappeared, there was no one left to regulate them. In the freshwater systems, rich in algae and bacteria, life was slow to recover.
The worst can still be avoided
Scientists say this toxic soup was the result of three main ingredients: accelerated greenhouse gas emissions, high temperatures, and abundant nutrients – the deforestation associated with volcanic eruptions, massive deforestation that dumped dust into rivers and lakes. Looking at the fossil record of other mass extinctions, scientists have found similar evidence.
What is alarming is that all three of these ingredients are present on Earth today. “We know that the rate of CO2 accumulation back then was similar to the rate of CO2 increase we see today due to anthropogenic forcing,” says geoscientist Tracy Frank in a statement from the University of Connecticut. The average temperature of our planet is rising. And nutrients are flowing into our waters due to agricultural pollution and deforestation. As a result, “we are already seeing more and more toxic algal blooms in lakes and shallow marine environments,” notes Tracy Frank. These algae resemble permafrost organisms in texture, filament structure, fluorescence, and concentration. They thrive in freshwater temperatures of 20-32°C. This is exactly the range expected at mid-latitude by the end of this century.
Another major parallel with the Permian-Triassic mass extinction is that the temperature increase at that time coincided with a massive increase in forest fires. They wiped out entire ecosystems. And that’s what’s happening now in places like California, Siberia, Australia, and the Amazon,” adds Chris Fielding, who is also the author of the study.
Thus, we are today experiencing a kind of replication of the first symptoms of the greatest mass extinction on Earth. These are the signs of an ecosystem that is out of balance. But unlike in the past, we still have the opportunity to stop or at least slow down this process. By maintaining healthy waterways and limiting greenhouse gas emissions. We, humans, are used to thinking in fairly short time frames, but we should remember that “life on Earth took four million years to recover from the Permian-Triassic mass extinction.” “That’s sobering,” notes Chris Fielding.