Earth ‘faces mass extinction to rival biggest in our history’

THE biggest mass extinction in the Earth’s history was caused by global warming in the past – and we could be on course for another, scientists have warned.

The event – known as The Great Dying – happened 252million years ago and wiped out 96% of marine species and 70% of land creatures.

It is thought to have been triggered by huge volcanic eruptions in Siberia releasing greenhouse gases.

Now scientists warn that if greenhouse gas emissions from cars, factories and power stations continue unchecked, ocean warming could hit 50% of the level experienced during The Great Dying by 2300.

Before the Siberian eruptions created a greenhouse-gas planet, the Earth’s oceans had temperatures and oxygen levels similar to today.

There has been much debate over the cause of The Great Dying, with possible reasons including lack of oxygen, heat stress, high acidity or poisoning chemicals.

A study in the journal Science suggests it occurred after temperatures soared, preventing sea water from holding enough oxygen for marine creatures to survive.

Using computer simulations, scientists raised greenhouse gas levels to those of The Great Dying, causing ocean surface temperatures to rise by 10C. The modelling showed the oceans losing 80% of their oxygen.

Researcher Justin Penn said: ‘This study highlights the potential for a mass extinction arising from a similar mechanism.

‘This is the first time we have made a mechanistic prediction about what caused the extinction that can be tested with the fossil record, which allows us to make predictions about the causes of extinction in future.’