How Models Are Tested

Climate models earn credibility by testing against the past. Scientists run them using historical conditions and check whether they reproduce the actual climate. Modern models replicate the temperature record of the last century, the cooling that follows major volcanic eruptions, and the rhythm of the seasons. A model that cannot rebuild known history has little claim to forecast the future.

No model is perfect. Models struggle with cloud behavior — whether warming produces more low clouds (cooling effect) or fewer (warming effect) — and with regional precipitation patterns that depend on local geography too complex for global-scale grids.