Overview
- Researchers analyzed gases and fluids preserved in 1.4-billion-year-old halite crystals from northern Ontario, providing direct samples of ancient air.
- Measured concentrations were about 0.28% carbon dioxide (roughly ten times preindustrial) and about 0.78% oxygen (around 3.7% of modern levels).
- High CO2 combined with temperature signals from the salt supports a temperate, largely ice-free Mesoproterozoic climate despite a dimmer Sun.
- The oxygen level was high enough to support complex multicellular life, though the authors caution it may reflect a transient oxygenation event.
- The study by RPI’s Justin G. Park and Morgan Schaller was published in PNAS (DOI: 10.1073/pnas.2513030122) and calls for more samples to assess how representative this snapshot is.