We can only be confident that some geographical areas would experience temperature increases larger than the globally-averaged warming, while other areas would be less affected. Additionally, the models are not now capable of predicting changes in average precipitation on a regional or otherwise localized basis. The climate system is exceedingly complex, consisting of diverse processes and interactions involving the atmosphere, the oceans, the land surface, the biosphere, and snow and ice. However, uncertainties are introduced by this need to simplify the climate system to produce a tractable model. Processes on scales smaller than a model's resolution tend to be poorly represented.
Coarse resolution introduces uncertainty.
Consequently, some of the possible climate changes of societal importance cannot be simulated. Changes in regional climate, some of which are bound to be greater that the projected global changes, are a matter of speculation. Secondly, the focus of climate models has been primarily the atmosphere, secondarily the oceans. Incorporation of the land surface, the biosphere, biogeochemical interactions, and polar ice has been rudimentary. Yet the response to a change in climate forcing involves all the interactive parts, and these factors may serve either to amplify or to dampen the earth system response.