Ice cream

A couple of Warmenists attack the theory that increased solar activity shields us from cosmic rays, which in turn reduces the amount of low-level cloud formation and hence increase average global temperatures here. To give them credit, they include this handy chart:

Now, as VFTS is at pains to point out, "correlation does not equal causation", which is true, but I think we can rule out "coincidence". We can certainly rule out the idea that heavier cloud cover causes cosmic rays (if anything, clouds might reduce the number of cosmic rays reaching the measuring stations, surely?); or that there is an even more underlying force at work that causes both.

This is one of the key arguments put forward by said Warmenists:

The number of cases of sunburn and the consumption of ice cream both increase in summer but you cannot conclude that eating ice cream causes sunburn. For this reason we set out to try to prove one way or the other whether changes in the rate at which cosmic rays fall on the Earth could significantly influence cloud cover and so provide the undiscovered effect needed in the event that computer climate models are wrong.

Correct. Sunburn does not cause ice cream consumption or vice versa, but they are both caused by sunshine/hot weather. Having observed this, we can then look at the transmission mechanisms, which are "not using enough sun-cream" and "desire to eat cold things when it's hot" respectively.

To extend the analogy, I suppose it is possible that cosmic rays and low-level cloud cover are both caused by something else entirely (in which case, what?). The Warmenists do not propose this, so we are left with the reasonable assumption that cosmic rays do encourage low-level cloud formation.

I'm not sure that the transmission mechanism is that important (although the people who awarded the 1927 Nobel Prize certainly did). For example, "not using enough sun-cream" is only part of the transmission mechanism from sunshine -> sun-burn. We'd also have to 'factor' in the desire of a lot of people to have sun-tans; the fact that it's nice to lie outside when it's hot; look things like Vitamin D and melanin levels etc etc. It might even be that being sun-burnt is the natural human condition and that only cold weather and clothing prevent this becoming chronic.

Similarly, even if you don't have a clue about molecular biology or what melanin is, you are perfectly entitled to generalise and say that "sun-shine causes sun-burn". To wit, even if the CLOUD people disprove ionization as a transmission mechanism, that doesn't mean that there isn't one. Anyways, the first comment in the Warmenist thread deserves an honourable mention:

If things happening at the same time doesn't prove anything, then how can we link global warming to greenhouse gasses without contradicting that statement?