Effects of Snow and Ice Impurities and Atmospheric Aerosols on Radiative Forcing

The widely accepted Milankovitch theory connects glacial-interglacial cycles to changes in orbital forcing. A large climate response to weak initial orbital forcing implies strong positive feedbacks. This strong amplification is dominated by an increase in greenhouse gases and surface albedo (due to ice sheet growth and biofeedbacks). The role of aerosols in glacial-interglacial transition is supposed to be minor and has been occasionally neglected altogether. We present an alternative picture of the glacial-interglacial transitions in which aerosols in the atmosphere and impurities on the surface of ice sheets play an important role in radiative forcing that is then amplified by greenhouse gases and other feedbacks.