The stretching of the continents has caused extreme global warming •

The stretching of continents is likely to have caused one of the most abrupt and extreme global warming events in the history of our planet, a new study led by the University of Southampton has revealed. 56 million years old. During this episode, the Earth warmed by five to eight degrees Celsius, culminating in the “Paleocene-Eocene Thermal Maximum” (PETM) which lasted about 170,000 years and led to the extinction of many organisms from the deep seabed, fundamentally reshaping the course of evolution. of life on Earth.

Extensive stretching of continental plates in the northern hemisphere has dramatically reduced pressures in the Earth’s deep interior, leading to short-lived but intense melting in the mantle, experts say. The resulting volcanic activity coincided with – and most likely caused – the release of a massive amount of carbon dioxide into the atmosphere which exacerbated global warming.

“Despite the importance and broader relevance of PETM to global change today, the underlying cause is highly debated,” said study lead author Thomas Gernon, associate professor of Earth Sciences. at the University of Southampton. “It is generally accepted that a sudden and massive release of greenhouse gas carbon from the Earth’s interior must have been the cause of this event, but the magnitude and rate of warming is very difficult to be explained by conventional volcanic processes.”

Using records of rocks drilled beneath the seafloor near the edge of the Atlantic Ocean, Professor Gernon and his colleagues found evidence of an abrupt and widespread episode of volcanic activity across the North Atlantic Ocean that lasted over 200,000 years – a surprisingly similar duration to the PETM. This discovery prompted scientists to study a larger expanse of the North Atlantic, including present-day Greenland and the Faroe Islands. There, they discovered that the thick piles of lava that began erupting before the PETM exhibited an unusual composition, indicating a massive increase in the melting of Earth’s mantle.

“This finding is significant because we know that parts of the continental mantle in this region are enriched in carbonates, a major source of carbon,” Prof Gernon said. “This rapid increase in mantle melting probably released a very large volume of carbon – certainly more than we previously expected.”

According to the researchers, this intense volcanic activity was likely caused by tectonic forces stretching the landmass plates uniting Greenland and Europe, with the final phase of stretching causing substantial melting of the Earth’s mantle and resulting in the release of massive quantities. carbon in the atmosphere and rapid global warming.

“Such rapid events cause a fundamental reorganization of the Earth’s surface environment, altering large ecosystems,” Professor Gernon concluded.

The study is published in the journal Nature Geoscience.

By Andrei Ionescu, Personal editor