About 445 million years ago, about 85% of marine life on Earth then disappeared after a geological event. This is considered a mass extinction in the Ordovician period.
According to the New York Times, this extinction event has long been considered a great mystery in Earth’s history. Scientists have long debated its cause, as other mass extinction events have clear explanations.
” The Ordovician extinction event is always something of a strange thing,” said Stephen Grasby of the Geological Survey of Canada.
The Ordovician period is the second of the six periods of the Paleozoic. It takes place after the Cambrian and immediately followed by the Silurian.
Now Mr. Grasby and his associate professor David Bond from Britain’s University of Hull think they have found a solution to this mysterious event, and published their conclusions last month in the scientific journal Geology. .
According to them, simultaneous volcanic eruptions across the Earth released enough carbon dioxide to heat the planet and trigger two extinction waves that occurred on Earth just 1 million years apart.
If this is true, then the Ordovician extinction event is similar to the other extinction events because they were all caused by global warming.
Visual depiction of marine life in the Ordovician Period, between 485.4 and 443.8 million years ago. (Photo: New York Times).
Mr Bond and Mr Grasby came up with their theory after collecting Ordovician stones from a small stream in southern Scotland. They were then shipped to Vancouver, Canada for study. They found that when subjected to heat, the rocks released large amounts of mercury – an indication that they came from a volcanic eruption.
The rocks also gave off molybdenum and uranium – geochemical information suggesting that the oceans were devoid of oxygen. The most likely reason is that the Earth is warming rapidly, causing the oceans to run out of oxygen, and marine life to suffocate.
“Think of it like a bottle of Coca-Cola. If you store it in the fridge it will still have gas, but if you leave it on a table in the sun, the gas will quickly come out of the liquid. And you’re left with a bottle of Coke without carbonate,” explains Mr Bond.
According to the two scientists, most likely at this time, the Earth’s crust began to crack, and lava flows erupted from everywhere. This process causes large amounts of carbon dioxide and mercury to be released, leading to rapid warming of the Earth.
If this hypothesis holds, the first mass extinction event would have a similar origin to the others. For some scientists, this will give them more incentive to study these extinction events – which will give us a better insight into the human impact today, because we also release carbon dioxide and other greenhouse gases into the atmosphere.
Although it’s hard to believe, according to Seth Finnegan, a paleontologist at the University of California, Berkeley, humans are emitting greenhouse gases at levels equal to or more than previous extinction events on Earth. .