Volcanism, climatic change, and the geologic record

There is some evidence for correlation between climate cooling and enhanced volcanism on time scales from decades to 10⁶ years, but problems in dating the episodes make it difficult to establish cause-and-effect relationships. Climate cooling for longer than the stratospheric residence time of the areosols (a few years) requires that positive feedback mechanisms, such as snow/ice-albedo feedback, come into play, or that climatically significant eruptions in the past were more closely spaced in time than in recent centuries. On long time scales (10⁷-10⁸ years), release of CO₂ through subduction-zone volcanism is a major control of climate. Intervals of rapid ocean-floor accretion (and subduction) correlate with times of increased volcanism, high sea levels and warm global climates. Accretion-rate data can be used in biogeochemical models to estimate paleoatmospheric CO₂ levels. -from Author