The model of the Earth's climate change described here is based on the Earth's global evolution theory and adiabatic theory of the greenhouse effect. The main factor determining climate's temperature parameters is the atmospheric pressure. Glaciations at the end of Paleozoic-Phanerozoic time occurred due to a gradual atmospheric pressure decline as a result of nitrogen consumption by the nitrogen-consuming bacteria that removed nitrogen from the atmosphere and concentrated it in sediments. A warm period in the second half of Mesozoic was associated with the formation of the Pangaea supercontinent and intensified oxygen generation, which compensated for the lowered nitrogen partial pressure.