I am appalled at the level of scientific misunderstanding shown in the Skeptical Science “Confidence in climate forecasts” guest blog post by Kevin Judd (and, presumably, John Cook).
What climate models do is run “scenarios”, “what-ifs”, computations in which some parameters get changed, and everything else remains equal. That is a normal way of conducting risk analysis, but only if everybody keeps in mind that OF COURSE in the real world everything changes, and nothing remains equal.
The surface temperature, for example, is also affected by unknown variables such as future volcanic eruptions and solar activity. Hence, the actual temperature difference between 2010 and, say, 2050, is pretty much unknowable.
Climate models are therefore tools to probe risks and sensitivities, not crystal balls. As a matter of fact, they can’t, won’t and never will tell us anything precise about future weather, weeks, months, years or centuries in the future: just as no donkey will ever win the Kentucky Derby.
That doesn’t mean climate models (or donkeys) are useless: rather, they should be used for what they are worth using.
And yes, you can ask Gavin Schmidt if you don’t believe me 😉
ps some will say that the difference between “forecast” and “scenario” is lost among the general public. Well, as Einstein would have it, scientific communication should be made as simple as possible, but no simpler.
And why is this so important? Schmidt again: “there is a real danger for society’s expectations to get completely out of line with what eventually will prove possible, and it’s important that policies don’t get put in place that are not robust to the real uncertainty in such predictions“.