The backbone of the IPCC climate assessment is the Coupled Model Intercomparison Project (CMIP). The term coupled means that the model can evaluate the whole system, i.e., atmosphere and ocean. Intercomparison suggests that climate models, developed by various groups at different points in time, are harmonised using the same set of inputs (provided by CMIP). This way, if there are differences between models’ predictions, it can be assured that it was not due to variations in experimental design but due to the difference in physics or the mathematical treatments.
Climate models are mathematical representations of complex geo-chemical-physical aspects and relate various inputs to the observed features of global warming. It gives better control over the underlying science but more importantly, it serves as a framework for forecasting.
The tool, currently at version 6, is a collaborative framework aiming to improve the understanding of climate changes related to global warming. The tool compares climate models, developed by various groups, with the experimental data and to each other.
The multi-model mean captured by CMIP6 closely matches the Global Mean Surface Temperature (GMST), although there can be differences in the predictions of individual models with the observed data.
Climate Reports: IPCC
Introduction to Climate Models, CMIP
