Earth's Chemistry Wobbled Before Five Major Mass Extinction Events

From its beginnings as basic microorganisms to the astonishing diversity of species alive today, life on Earth has never had an entirely peaceful history.

Mass extinction events can appear to strike with little warning, eliminating vast numbers of species and creating opportunities for others to replace them.

Yet mass extinctions are not caused solely by catastrophes such as supervolcanoes and asteroid impacts. New research indicates that, around five of the largest mass extinction events ever recorded, Earth's chemistry 'wobbled'.

Seen in retrospect, this instability was a warning of the transformation ahead.

The study, published in Nature Communications, finds that Earth moved through five separate climate regimes over the past 539 million years. Each was divided from the next by abrupt transition phases involving rapid environmental change.

The researchers report that life was especially susceptible to mass extinction during these transitions, providing a new historical account of why certain eras experienced such severe biodiversity losses.

Two ocean-chemistry signals (oxygen and carbon isotopes) tracked across 500 million years, with skull icons marking the 'Big 5' mass extinctions and orange highlights showing where the chemistry gave early warning signs of a coming shift. (Livina et al., Nature, 2026)

Biosphere vulnerability and mass extinction risk

The research introduces a measurement of overall 'biosphere vulnerability'. Combining origination and extinction rates with existing biodiversity, it indicates whether Earth is in a phase in which mass extinctions are more probable.

This indicator of biotic stress "increases when we have increases in extinction rates and origination rates which also represent a drive to adapt to new and challenging conditions," study co-author Andrej Spiridonov, a palaeontologist and Earth systems scientist at Vilnius University in Lithuania, told ScienceAlert.

"It also increases when diversity decreases, thus also reflecting the contraction of biotic possibilities. It should be noted that vulnerability is an ensemble metric, and when the biospheric state is vulnerable, it doesn't mean that every single species or even region of the world is 'stressed'."

It's not just disasters like supervolcanos and asteroid impacts that cause mass extinction. (Mark Garlick/Science Photo Library/Getty Images)

For those interested in the mathematics, the biosphere vulnerability index is a straightforward formula. It uses the natural logarithm of the total intensity of total turnover - the combined rate at which taxa arise and become extinct - compared with standardised standing diversity.

Put simply, it measures the pace of ecological change against total biodiversity, showing whether an ecosystem is unstable and thus exposed to still more dramatic change.

When the team tested the index, they found that total vulnerability differed across the five periods they identified. Each of these endured for between 10 and more than 100 million years.

The researchers termed these periods 'Haggis bins', because several of their graphs resembled the Scottish dish. Within them, greater susceptibility to extinction and biodiversity decline broadly tracked higher temperatures.

They also found that warmer eras generally aligned with increased underlying biosphere vulnerability.

Climate transitions, the 'Big Five', and warning signs

Biosphere vulnerability surged, however, at the point where one period ended and another began. The 'Big Five' mass extinctions likewise coincided with peaks in vulnerability.

Spiridonov said this does not demonstrate that environmental turbulence itself causes mass extinction. In some instances, for example, another event - such as a huge asteroid impact - is known to have played a role.

Instead, the findings suggest these transitions may warn that life on Earth is temporarily more fragile than usual, leaving it more vulnerable should another disaster occur.

Vulnerability mapped against the 'Big 5' mass extinctions. (Livina et al., Nature, 2026)

"When the system approaches a critical transition," he said, that offers information "on possible future impending great change, such as a mass extinction or even a series of them."

What might this mean for the present day?

The study is a historical assessment and cannot forecast what lies ahead for humanity or other species now living through an ongoing climate crisis and a period of accelerated extinction.

Related: Earth's Biggest Mass Extinction Reveals Chilling Parallels to Today's World

"Our study suggests that the current geological era – the Cenozoic – is exceptionally stable having low vulnerability," he explained.

"It doesn't mean that the external impact by geophysical forces or the human impact wouldn't have any significant effects on the evolution of the biosphere. It just means, that under different background conditions, which prevailed in other geological eras, such a disturbance would have had much higher effect."

The research has been published in Nature.

This article was fact-checked and edited by Peter Dockrill. Although we take pride in our process, we are only human. If you notice an error, please let us know.