Earth’s Chemistry Teetered Before the Five Great Extinctions
A Nature Communications study finds Earth’s climate oscillated through five distinct regimes over 539 million years, with rapid transitions that heightened life’s vulnerability and align with the planet’s Big Five mass extinctions. By tracking ocean oxygen and carbon isotopes and creating a biosphere vulnerability index, researchers show that higher temperatures and regime boundaries correlate with increased extinction risk, though the index measures overall system fragility rather than predicting specific events. The work offers a historical warning that, while the current era (Cenozoic) appears relatively stable, rapid environmental change can amplify the impact of disasters and push the biosphere toward instability.