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Humbugs: tasty but inaccurate

As a physics grad I don’t know a huge amount about modelling the Earth’s climate.  Nevertheless the previous post got me thinking about a couple of the common objections that frequently get trumpeted by the climate “sceptics” and why they strike me as somewhat fishy just from a general science perspective.

Although there are many flavours of climate humbug, the two arguments I’ll look at in this post seem to boil down to “we don’t need no stinking computer models – that’s not real science” and “your computer model doesn’t include an allowance for [], therefore we can’t trust its results”.  I’m leaving aside variants of “it was cold today therefore global warming doesn’t exist” comments as too asinine to contemplate further.

Climate denialists are exploiting stereotypes about scientists with their first complaint.  People have an image of scientists doing experiments in white lab coats with test tubes, not setting up a model on a computer and seeing what answers pop out.

However those stereotypes are outdated and don’t really line up with how a lot of science is done today.  As physicists don’t have any handy spare universes lying around, some experiments that we might want to do just can’t be done.  For example, large areas of astrophysics involve using the laws of physics to model what we expect to happen in the universe.   We can then look at the real universe to check our model’s predictions against reality.

Similarly as we don’t have any spare Earths to play with (although I hear Magrathea is working on it) climate scientists have to make do with computer models.  Testing of the models is done using records of what happened in the past, including inferences of the historic climate from the geological record.

On the surface the second objection seems more reasonable.  Certainly if climate scientists were ignoring important variables in their models then this could throw their results in doubt.  The only problem is that the denialists seem to latch onto things that either are already included in climate models or just aren’t important enough to affect the results.

When building a model of how the world works you don’t need to include every detail.  Simplifications and abstractions are the norm.  When driving across London to visit a friend in Clapham I’ll consult a 2-D map that will ignore the fact that the surface of the Earth is curved.  The omission of this detail will not affect my ability to find my friend’s house.  However when putting a satellite into orbit NASA scientists will certainly take into account the curvature of the Earth, although they will still simplify things by assuming the Earth is perfectly spherical.  When flying a plane a pilot who assumed the Earth is perfectly spherical might end up crashing into an inconvenient mountain.  For the pilot knowledge of the bumps on the Earth’s surface would be essential.  Broadly the use to which we put our model will influence the details that we include.

I’m sure none of this is really news to the denialists themselves – they have undoubtedly had this explained before.  However laymen and naïve journos should bear it in mind before accepting their superficially plausible patter.