Snapshot record of CO2 and CH4 from the Allan Hills, Antarctica, ranging from 400,000 to 3 million years old

This dataset contains snapshots of carbon dioxide and methane concentrations, total air content, stable isotope measurements of carbon dioxide, as well as measurements of molecular oxygen and nitrogen and their stable isotopic signatures. Samples come from the ALHIC1901 ice core from the Allan Hills, Antarctica. Where possible, new ages have been assigned to previous measurements from the ALHIC1503 ice core. For samples containing excess CO2 from a secondary source, estimated atmospheric CO2 ranges are included.