A chemical signature preserved in rocks for nearly 2 billion years has long been used to reconstruct one of the most consequential chapters in Earth’s early history. Scientists had interpreted the unusual carbon-isotope pattern as evidence of a major disruption to the planet’s carbon cycle, occurring around the time oxygen began accumulating in the atmosphere.
A new study from researchers at the California Institute of Technology (Caltech), however, suggests that at least one key record of this event may have had a much smaller origin.
