6.2.11 (HL)—Global climate models

A climate model maps inputs and assumptions through physical processes to outputs that can be tested against observations.

Inputs include forcing and boundary conditions; processes represent atmosphere, ocean, ice and land; outputs include temperature, rainfall or extremes. Hindcasting tests structure but cannot prove every future detail.

A model that reproduces past warming under observed emissions gains support, but unresolved clouds still affect future projections.

It tests consistency with known data, while future forcing and model uncertainty remain.

Model uncertainty does not make a model useless; it tells you how strongly to qualify the output.