Researchers at Caltech studied pyrobitumen-rich rocks from Karelia, dated to roughly 2.5 to 2 billion years old, and found an unusual carbon isotope signature. This discovery challenges the popular theory about how oxygen first became abundant in Earth's atmosphere, known as the Great Oxidation Event. The findings suggest that microbial biomass burial and carbon sequestration during that period may have followed a different pattern than previously assumed. This matters for climate science because understanding past carbon cycles helps refine models of long-term carbon storage and atmospheric composition. The isotope data could also affect how scientists interpret paleoclimate records used to predict future climate behavior. The study adds a new layer of complexity to our understanding of how life and the planet co-evolved.
