title: Comment on "Long-term climate forcing by atmospheric oxygen concentrations".
abstract: Poulsen et al (Reports, 12 June 2015, p. 1238) argued that lower atmospheric oxygen levels during the Phanerozoic would have given a warmer climate. However, radiative and atmospheric structure changes under lower pressure both cause cooling, making their result unusual in that a hierarchy of models gives opposing results. Scrutiny of how radiative and cloud processes were represented, and a mechanistic explanation of the results, are required.
authors.affiliation: School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada.
authors.forename: Colin
authors.initials: C
authors.lastname: Goldblatt
mesh_terms: D001272:Atmosphere / Q000737:chemistry; D002980:Climate; D008962:Models, Theoretical; D010100:Oxygen
chemical_list: D010100:Oxygen