8.7.2.3 Volcanoes

Volcanoes produce abrupt climate responses on short time scales. The surface cooling effect of the stratospheric aerosols, the main climatic forcing factor, decays in one to three years after an eruption due to the lifetime of the aerosols in the stratosphere. It is possible for one large volcano or a series of large volcanic eruptions to produce climate responses on longer time scales, especially in the subsurface region of the ocean (Delworth et al., 2005; Gleckler et al., 2006b).

The models’ ability to simulate any possible abrupt response of the climate system to volcanic eruptions seems conceptually similar to their ability to simulate the climate response to future changes in greenhouse gases in that both produce changes in the radiative forcing of the planet. However, mechanisms involved in the exchange of heat between the atmosphere and ocean may be different in response to volcanic forcing when compared to the response to increase greenhouse gases. Therefore, the feedbacks involved may be different (see Section 9.6.2.2 for more discussion).