Hence an AGCM by itself cannot be used for climate prediction, because it cannot indicate how conditions over the ocean will change. AGCMs are useful for studying atmospheric processes, the variability of climate and its response to changes in sea-surface temperature. This kind of model is useful for simulating what the climate would be like for some fixed level of carbon dioxide, but it cannot be used for predicting the rate of change of climate because this is largely determined by processes in the ocean interior. OGCMs are useful by themselves for studying ocean circulation, interior processes and variability, but they depend on being supplied with data about surface air temperature and other atmospheric properties. The carbon cycle model is needed in order to capture several important climate feedbacks on carbon dioxide concentration, for instance fertilisation of plant growth by carbon dioxide and uptake or outgassing of carbon dioxide by the oceans.
Further information is available about ocean carbon cycle modelling .
The chemical scheme is designed to include the main agents responsible for the production and destruction of ozone and methane in the lower atmosphere. Some recent models include the biosphere, carbon cycle and atmospheric chemistry as well. They are also used to study the variability and physical processes of the coupled climate system. Global climate models typically have a resolution of a few hundred kilometres. At the Hadley Centre, this was first done in 1999.