New study provides startling timeline for Earth’s sixth mass extinction

(Credits: Paul Souders/Getty Images)

Translated by Julio Batista
Original by Carly Cassella for the ScienceAlert

A climatologist from Tohoku University in Japan has looked at the numbers and doesn’t think the current mass extinction event will be the same as the previous five. At least not for several centuries.

On more than one occasion in the past 540 million years, the Earth has lost most of its species in a relatively short geologic period.

These are known as mass extinction events and are often fueled by climate change, either extreme warming or extreme cooling, triggered by asteroids or volcanic activity.

When Kunio Kaiho attempted to quantify the stability of Earth’s average surface temperature and the planet’s biodiversity, he found a largely linear effect. The greater the change in temperature, the greater the extent of extinction.

For global cooling events, the largest mass extinctions occurred when temperatures dropped by around 7°C. But for global warming events, Kaiho found that the largest mass extinctions occur with an increase of around 9°C.

It is much higher than previous estimateswhich suggest that a temperature of 5.2°C would cause a major marine mass extinction, on par with the previous “big five”.

To put this into perspective, by the end of the century, modern global warming is on track to increase surface temperatures by up to 4.4°C.

“A global warming of 9°C will not appear in the Anthropocene until at least 2500 in the worst case”, to predict Go on.

Kaiho does not deny that many extinctions on land and at sea are already happening due to climate change; he just doesn’t expect the same rate of extinction as before.

Yet it is not just the degree of climate change that puts species at risk. How quickly this happens is vitally important.

The largest mass extinction event on Earth killed 95% of known species at the time and took place over a period of more than 60,000 years, about 250 million years ago. But the current warming is happening on a much shorter timescale, thanks to human emissions of fossil fuels.

Perhaps more species will die in Earth’s sixth extinction, not because the magnitude of the warming is so great, but because the changes happened so quickly that many species failed. to adapt.

“Predicting the magnitude of future anthropogenic extinction using only surface temperature is difficult because the causes of anthropogenic extinction differ from the causes of mass extinctions in geologic time,” admits Kaihu.

However scientists divide the data, it’s clear that many species are doomed unless we can stop climate change.

The exact percentage of extinction and the timing of these extinctions remains up for debate.

The study was published in Biogeosciences.

Leave a Comment