The problem of paleotemperatures of the earth surface

An analysis is presented of the investigation by Epstein et al. (1976) of the cooling of the earth surface during the past three billion years. Epstein et al. used isotopic methods to determine that three billion years ago the mean annual temperature of the surface was 70 C, that 1.8 billion years ago it was 35 C and that 230 million years ago it was 20 C (the present temperature of the surface is 14.8 C). In the present paper these data are analyzed with reference to processes of natural-gas formation. Consideration is given to the distribution of paleotemperatures during the past three billion years also in the context of the Jakobs-Allan thermal model of the earth surface (1956). Mars and Venus thermal data are also considered in light of the models discussed.