Climate Change Global Warming Omniclimate Science Skepticism

'Skeptical Science' Falls For The Unscientific

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).

There is no such a thing as a “climate forecast” (yes I have raged about this same point in the past, for example here and here)

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“.

0 replies on “'Skeptical Science' Falls For The Unscientific”

I am going to agree and disagree with you here.

There are indeed climate forecasts, but they are, as you point out contingent forecasts. Sometimes we call those scenarios.

Everything we project into the future requires by definition some priors. Every single time, there is some assumption on which the forecast is based – be it an exogenous variable, an assumed mathematical form, even an assumption that “there are no unanticiapted influences”.

All the climate scenarios need to be avaluated for what they are – contingent forecasts. Look at John Christie’s recent retrospective on Hansen 1988 as a perfect example. How well does our hypothesis forecast, after trying to take account of the assumptions or unfactored influences that also occurred.

The problem with climate models is not necessarily the model itself but the apparently broad misunderstanding of the value or usefulness of the model. Too many climate scientists believe (or knowingly perpetuate a falsehood) that a model run can be equated with a scientific experiment.

A comment I have left at Skept Sci:

doug_bostrom (#46): not really indicative of any problem w/scientific understanding

I used to believe that, but then I have seen the f-word used so often by otherwise knowledgeable people, I am now inclined to think those using it have really lost its real-world meaning.

chris (#50): No, nobody thinks they have a crystal ball, but (too) many people talk to the general public as if they did!

I confess I am always amazed at how much I agree with Schmidt on this point. And especially about society’s expectations. Perish the thought there would be a +3C increase by the year 20XX apart from a 1C drop due to a series of volcanic eruptions, with the resulting 2C hailed a victory for humanity’s efforts and politicians’ especially (come to think, if you look at the Copenhagen Accord cloosely, it’s worded ambiguously enough…)

And for the record, yes, I am all for the use of climate models, even if like with string theory, I do think there’s been too much focus on them and them alone.

Like secret dossiers for journalists, climate models make a climatologist’s life easier, maybe too much so.

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