Long term variations in the albedo and surface temperature of the Earth

THE surface temperature of the Earth depends primarily on the solar constant, the Earth's albedo and the total mass and chemical composition of the terrestrial atmosphere. Studies of climate covering the past few million years have generally allowed for variations in albedo in calculating average values of the surface temperature. But over longer periods of time, however, less allowance has been made for albedo variations; it has, indeed, frequently been assumed that the albedo, when averaged over a long enough time, can be taken to be constant (see ref. 1). We wish to point out that, on the contrary, long term variations in the albedo can be expected to occur, and to produce significant changes in the average surface temperature.