DR FINKEL SAYS:

In the difficult world of modelling, often the predictions are right, occasionally they are wrong. The Intergovernmental Panel on Climate Change bases its scenarios on the averaged outputs of many sophisticated, data-driven models.

As a sanity test, the models are tested by feeding them with historical data from 20 or 30 years ago to see whether they can predict the current climate. Over the years they have been passing this kind of test with increasing accuracy.