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250 million years ago Earth suffered the most massive extinction of life and now scientists know why

2025-07-05 19:25:34Histori SHKRUAR NGA REDAKSIA VOX
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About 252 million years ago, life on Earth suffered its most catastrophic blow to date: a mass extinction known as the "Great Extinction," which wiped out about 90% of life.

What happened next has puzzled scientists for a long time. The planet became extremely hot and stayed that way for 5 million years.

Now, a team of international researchers says they have finally discovered the reason, and it all has to do with tropical forests.

Their findings, published in the journal Nature Communications, may help solve a mystery, but they also provide a dark warning about the future as humans continue to influence the warming of the planet through the burning of fossil fuels.

The "Great Extinction" was the most severe of the five mass extinction events that have marked Earth's history, and it marked the end of the Permian geological period.

This event has been attributed to a period of volcanic activity in a region known as the Siberian Traps, which released large amounts of carbon and other greenhouse gases into the atmosphere, causing extreme global warming. Large numbers of terrestrial and marine plants and animals became extinct, ecosystems collapsed, and the oceans acidified.

But what has been less clear is why the planet became so hot and why the "super-greenhouse" conditions persisted for so long, even after volcanic activity had ceased.

"The level of warming is beyond any other event," said Zhen Xu, one of the study's authors and a researcher at the School of Earth and Environment at the University of Leeds.

Some theories have focused on the oceans, suggesting that extreme heat wiped out carbon-absorbing plankton, or changed the ocean's chemical composition, making it less effective at storing carbon.

But scientists from the University of Leeds in England and the China University of Geosciences thought the answer might lie in a climate tipping point: the collapse of tropical forests.

The mass extinction event during the "Great Extinction" is unique "because it's the only one in which all plants disappear," said Benjamin Mills, another author of the study and professor of earth system evolution at the University of Leeds.

To test the theory, they used an archive of fossil data in China that has been collected over decades by three generations of Chinese geologists.

250 million years ago Earth suffered the most massive extinction of life and now

They analyzed fossils and rock formations to get clues about past climate conditions, allowing them to reconstruct maps of the vegetation and trees that lived in every part of the planet before, during and after the extinction. "No one has created maps like this before," Mills told CNN.

The results confirmed their hypothesis, showing that the loss of vegetation during the mass extinction event significantly reduced the planet's ability to store carbon, meaning that very high levels remained in the atmosphere.

Forests are an important climate buffer, absorbing and storing carbon that warms the planet. They also play a key role in “silicate exchange,” a chemical process between rocks and rainwater, a crucial way to remove carbon from the atmosphere. The roots of trees and plants help this process by breaking down rock and allowing water and air to penetrate.

When forests disappear, "you're changing the carbon cycle," Mills said, referring to the way carbon moves around the Earth, between the atmosphere, land, oceans and living organisms.

Michael Benton, professor of palaeontology at the University of Bristol, was not part of the study, but said the research shows that “the lack of forests seriously affects the normal oxygen and carbon cycles and prevents carbon from being lost, causing high levels of CO? to remain in the atmosphere for long periods.”

He emphasizes “a threshold effect,” where forest loss becomes “irreversible on ecological time scales.”

Global policies today are based on the idea that if carbon dioxide levels are controlled, the damage can be undone.

"But at the critical threshold, then it becomes difficult for life to recover," Benton said.

That's a key message from the study, Mills said. It shows what could happen if rapid global warming causes tropical forests to collapse in the future, a tipping point that worries many scientists.

Even if humans completely stop the pollution that warms the planet, the Earth may not cool. In fact, warming may accelerate, he said.

There is a glimmer of hope: The tropical forests that currently cover the planet may be more resistant to high temperatures than those that existed before the Great Extinction. That's the question scientists are now trying to understand.

However, this study is a warning, Mills said.

"There is a tipping point. If you warm the rainforests too much, then we have very good evidence of what happens. And it is extremely bad," he said.

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