Geological observations of Mars indicate a dense early atmosphere ranging from 0.25 to 4 bar of carbon dioxide. But 3.5 billion years ago, the Martian atmosphere thinned rapidly to approximately 0.054 bar, suggesting a substantial loss of atmospheric carbon dioxide, either to space or the lithosphere. The mechanism by which Mars lost its carbon dioxide remains poorly understood. For MIT geologists Joshua Murray and Oliver Jagoutz, the answer may lie...
