Ancient mass extinction shows how Earth turned into a super-greenhouse

After a sharp increase in atmospheric carbon dioxide levels 252 million years ago, forest deaths led to a long -term change in the earth climate, the persistent greenhouse conditions for millions of years.

Scientists working to understand this event, which has caused the greatest mass extinction in the history of the earth, warn that a similar story could take place if we continue to issue greenhouse gases.

The permien-triassic extinction event would have been triggered by a massive volcanic activity in the region which is now Siberia, which has increased CO2 levels in the atmosphere.

The surface temperature of the planet has increased up to 10 ° C and, in equatorial regions, the average surface temperature has climbed to 34 ° C (93 ° F) – 8 ° C higher than the average today.

These conditions persisted for about 5 million years, which led to the extinction of more than 80% of marine species and 70% of families of land vertebrates, according to certain estimates.

While some researchers recently argued that these mass extinction events have in fact had minimal effects on terrestrial ecosystems, Andrew Merdith at the University of Adélaide in Australia is convinced that, from 252 million years, life has been put on their knees.

“Pockets of life could survive through mass extinction in small enclaves or oases here and there, but you can go to many sections of the permian trias of the fossil file and see that whole ecosystems have turned off,” explains Merdith.

He and his colleagues studied the fossil record to understand why the Super Greenhouse event stimulating mass extinction lasted 5 million years instead of the 100,000 years that climate models predict that he should have.

They found that, through huge stretches of earth, the forests with awnings of up to 50 meters high were replaced by robust terrestrial cover plants 5 centimeters to 2 meters in height. The peat bogs, another ecosystem that stores large quantities of carbon, were also destroyed in tropical regions.

Using an IT model of the climate and the geochemistry of the earth, the researchers showed that the loss of these ecosystems meant that CO2 levels remained high for millions of years. This is mainly due to the fact that the vegetation has a great impact on alteration, a process that draws carbon from the atmosphere and stores it in rocks and soil on long ladders.

There are strong parallel with the present, says Merdith, because CO2 levels in the atmosphere increase quickly. If temperatures continue to increase, then tropical and subtropical forests can find it difficult to adapt, crossing a threshold where the vegetation can no longer play its crucial role in the balance of the climate.

Merdith says that the new work shows that you do not get a “ping-pong effect”, where the atmosphere can quickly recover after the loss of equatorial forests.

“It is not as if you were in a counterpart, then you go to a greenhouse a little, then go down directly to an ice house,” he said. “Once you started the ball, the earth finds its new point of balance, which is not necessarily what it was before.”

Katrin Meissner at the University of New South Wales in Sydney, Australia, which was not involved in the study, says that the reconstruction of these events is like “putting a puzzle with many missing pieces”, but that the argument of the team is “plausible”.

However, there is still a lot of uncertainty about what was going on in the oceans at the moment, she said. “The oceans have much more carbon than the earth and the atmosphere combined, and we really have no idea what happened to ocean biology, chemistry and physical traffic during this event,” explains Meissner.