On geological timescales, carbon dioxide enters the atmosphere through volcanism and oxidation of organic matter, and is removed through mineral weathering and carbonate burial. An analysis of ice-core CO2 records and marine carbonate chemistry indicates a tight coupling between these processes during the past 610,000 years, which suggests that a weathering feedback driven by atmospheric CO2 leads to a mass balance between carbon sources and sinks on long timescales. The cover image shows an eruption of Augustine Volcano, Alaska on 26 March 2006. Volcanic eruptions and outgassing release CO2, as well as ash and other gases, to the atmosphere.
Image credit: Cyrus Read.
Cover design by Karen Moore