About 252 million years ago, the earth saw catastrophic destruction – an eradication event so severe that it wiped out almost all of life on Earth.
Up to 70 percent of all vertebrate species were killed and a massive 96 percent of all marine species, including the famous trilobite, who had previously survived two other mass eradication events.
It's called the Permian-Triassic Extinction Event, also known as The Great Dying, and as far as we know, it was the most calamitous event in Earth's history.
It is widely acknowledged that climate change is due to – more specifically, that long-term volcanic activity in Siberia spades so much material into the atmosphere that it wrapped the world in a ash for a million years while blocking sunlight, dying ozone, losing sour rain and elevates temperatures.
Now scientists have shown what wiped out marine life: rising temperatures accelerated the metabolism of marine animals, which increases their oxygen requirements while depleting the oceans' oxygen.
The animals choked literally.
And we experience similar atmospheric warming again today – only much faster than the big dying who showed warning signs for 700,000 years before the event itself.
"This is the first time," said oceanographer Justin Penn of the University of Washington, "that we have made a mechanistic prediction of what caused the extinction, which can be tested directly with fossil registration, enabling us to make predictions of causes of extinction in the future. "
The team implemented a computer simulation of the changes that the earth underwent during the great dying. Prior to the Siberian volcanic eruptions, temperatures and levels of oxygen were the same as they are today, giving them a good basis for working out.
Then they raised greenhouse gases in the model's atmosphere to mimic the conditions after the eruption, which increased the sea surface temperature by about 11 degrees Celsius (at 20 degrees Fahrenheit).
Sure enough, this resulted in an oxygen discharge of about 76 percent – and about 40 percent of the seabed, mostly at greater depths, was completely depleted of oxygen.
To observe how this would affect the life of the sea, the team made oxygen data from 61 modern species into the simulation. It was a disaster.
"Very few marine organisms remained in the same habitats they lived in – it was either to escape or perish," said oceanographer Curtis Deutsch of the University of Washington.
The hardest hit were creatures most sensitive to oxygen, with the most pronounced destruction at high latitudes far from the equator. When the team compared their results with the fossil record, they confirmed their results.
This is because animals living in the warmer waters around the equator can move to higher latitudes, where they will find habitats similar to those they just left. However, animals that are already living in higher latitudes have no place left.
Overall, researchers found that this accounted for over 50 percent of Great Dying's marine diversity loss. The rest was probably caused by other factors such as acidification of CO2 from the Siberian traps and a sharp fall in plant life caused by the diluting ozone.
We must sit up and pay attention to this, say the researchers. The temperature rise of 11 degrees Celsius took a couple of thousand years, giving or taking.
Since 1880, the Earth's average temperature has risen by 0.8 degrees Celsius (1.4 Fahrenheit) – and two thirds of this increase has occurred since 1975. And the warming of the Earth's oceans accelerates.
"During a business-as-usual emission scenario, at 2100 heating in the upper seas will have approached 20 percent of warm-air heating, and in the year 2300 it will reach between 35 and 50 percent," Penn said.
"This study highlights the potential for a mass eradication due to a similar mechanism under man-made climate change."
Keep in mind that.
The team's research has been published in the journal Science.