We propose that for any geography, halving the amount of emergent land area will elevate CO2 levels enough to raise land surface temperature 10 °C and vice versa. We have evaluated this relation by specifying latitude and level of emergence for six end-member continental configurations. We show that a world with polar continents (capworld) will be warmest, whereas a world dominated by tropical ones (ringworld) will be coldest—a result superficially counterintuitive to established climate dogma. A meridional configuration (sliceworld) will have intermediate temperatures. The model is consistent with modern, Pleistocene maximum-emergence and mid-Cretaceous minimum-emergence climates. It also predicts a cool global climate for the half-emergent mid- Cambrian ringworld and a very warm, equable climate for the half-emergent mid- Silurian capworld. Furthermore, the relations among latitude, land area, temperature, and CO2 levels predict that a Late Proterozoic, equator-straddling landmass could have been glaciated. A strong point of the model is that it yields realistic results with no knowledge of paleolongitude, sea-floor- generation rates, or orogeny (or, by implication, degassing and erosion rates), none of which is obtainable for pre-Mesozoic paleogeographies.