That proportion of solar radiation reflected from a surface, such as clouds (low from thin stratus cloud; up to 80% from thick strato-cumulus), or bare rock. Lighter, whiter bodies have higher albedos than darker, blacker bodies. Earth’s total albedo is about 35%. The ice-albedo feedback mechanism occurs when a reduction in greenhouse gases in the atmosphere, principally carbon dioxide and methane, make the global climate colder, creating larger areas of ice and snow. Ice and snow reflect more solar radiation than does bare ground or liquid water, which creates a ‘positive feedback’. If the Earth ever became half-covered by ice or snow, the feedback would become self-sustaining and glacial ice would rapidly spread to the equator

Zhang et al. (2012) find that, over the last 300 years, surface albedo decreased due to conversions from grassland to cropland in the Northeast China Plain and increased due to conversions from forests to cropland in the surrounding mountains.

Land surface albedo is an important variable in General Circulation Models; see Roesch (2002) J. Geophys. Res. 107, 4221. See also Tasum et al. (2008) J. Hydrol. Eng. 13, 2, on the retrieval of land surface albedo from satellite observations.