An overview of climate models

Climate models and results, especially for paleo-climatic scale are reviewed. It is concluded that the climatic system is more stable than it was thought to be when Budyko-Sellers type models first came into existence. Even a 2% decrease in solar radiation may not result in White Earth due to negative feed-backs. A decrease in CO₂ to about 200 ppm can result in White Earth. A doubling of CO₂ increases the surface temperature by an order of 1°C. The total climatic system which is nonlinear can exhibit very long period internal oscillations, even of the order of 1,00,000 years though none of the time constants involved are in that range individually.