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I'm skeptical, on several levels. One, the cosmic ray to dust causal mechanism seems rather weak. In fact, every one of the causal links seems rather weak, putting most of the weight on the statistical analysis. That is rarely a good sign.

Two, it is easy to encounter spurious correlations in long times series. When you see "correlations" "reverse" numerous times in a 300 year time series, the most plausible explanation is not a complicated twiddle flipping on and off at irregular intervals, it is just that there isn't any real correlation at all. No correlation and rapidly and irregularing switch correlations look precisely the same.

And you'd expect to find irrelevant matches to imputed "flips" in correlations to any of dozens of other series over the same period. Like correlations between who wins the super bowl and which way the stock market goes, these mean nothing. But will automatically arise for some matches, just because each goes one of two ways every year.

A good test of whether one might be being fooled by such effects is the scale of the supposed flips in correlations compared to the overall length of the time series. You expect "runs" of length on the order square root of overall length, even from purely random, unreal relations. So if you see 15-20 years of x, and 15-20 years of y, in a 300 year time series, there is every reason to be suspicious that it is purely an artifact.

The article also notes 0.5% variations in solar activity over typical solar cycles. That amounts to approximately 2 watts per square meter (adjusted for only part of the earth's surface being illuminated, etc). Which incidentally is about the scale of modeled greenhouse effects from past observed CO2 changes, and about half those predicted for doubling atmospheric CO2.

There is also at least anecdotal evidence that the variations in solar activity over more pronounced solar cycles, less frequent and associated with more extreme changes in sunspot activity, may be somewhat larger, perhaps double. In particular, the "solar minimum" associated with the first half of the 1600s had astronomers reporting virtual no sunspot activity for extended periods, while tree ring data says climate got significantly cooler.

The most plausible explanation of these effects is not through a twiddle with dust and cloud formation, or any resulting amplification of signal, but simply through varied total solar output, directly to mean (and equilibrium - some short run transition effects) temperature. Unless the ice core data force an assumption of large amplification of solar variation signal, there is very little reason to suppose there is any.

Indeed, part of this looks to me like another "amplifier hunt", trying to find something - anything - in the climate system that can take a tiny input (of the scale of variations normally seen) and boost its climatic effects 10 fold. For those in Palm Beach who may think such things are a matter of course, that is not at all the case.

There are scads of mere allegations about possible mechanisms of that kind. But only allegations. The reason there are so many is the whole global warming crowd needs such amplifiers, because the mechanism they do have (CO2 direct greenhouse) are too small to support their scaremongering predictions. This results in a regular crop of "maybe there is this" or "maybe there is that", all amplifiers, whose sole motivation is to save the prediction, not to investigate the actual linkages among subsystems of the global climate.

But typically when such things are investigated by serious physicists, they don't show large scale amplification effects for anything like the scale of variations typically seen. Thus, some said "maybe cloud cover is so sensitive that is magnifies small changes in a power "driver" into large temperature effects". Maybe pigs have wings. Go look, and you find cloud cover over a period of decades changes by on the order of 1 percent, in the wrong direction, thus acting as a minute damping force but basically letting changes to power terms effect global mean temperature "as is". Go look, and pigs don't have wings, either.

To me this report looks like statisical data mining of artifacts out of long time series in support of allegations of climatic amplifiers. The fact that they link it to sun activity rather than CO2 variation might make naive readers think they are global warming debunkers, and individually they might be for all I know. But the general technique (time series mining) and characteristic conclusion (some complicated hypothetical twiddle with weak causal links is supposed to dramatically amplify minute power term changes) both stick out like sore thumbs, screaming "epicycle hunt."