New Scientist covers Alec Rawls' leak of the AR5 draft, and more particularly the resulting focus on the solar influence on climate. The article can be seen here. Now solar is not really my thing, so I'm feeling my way here somewhat, but it seems to me that the New Scientist piece doesn't really address the argument made.
Rawls' case was based around the following statement from Chapter 7.
Many empirical relationships have been reported between GCR or cosmogenic isotope archives and some aspects of the climate system (e.g., Bond et al., 2001; Dengel et al., 2009; Ram and Stolz, 1999). The forcing from changes in total solar irradiance alone does not seem to account for these observations, implying the existence of an amplifying mechanism such as the hypothesized GCR-cloud link. We focus here on observed relationships between GCR and aerosol and cloud properties.
OK, so if I understand correctly, the climate changes in line with cosmic rays. Cosmic rays change in line with the sun's output. But the changes in output are insufficient to explain the changes in climate, so the deduction is that these changes must be amplified in some way - in other words that there is a direct and an indirect effect of TSI on climate. One possibility is that the indirect effect is that variations in solar output affect the number of cosmic rays' reaching earth which affects cloud formation. However, the paragraph above implies that it is possible that it could be something else too.
Chapter 7 then goes on to say that the cosmic ray/cloud link is too weak to be responsible. This would seem to me to leave open the possibility that the amplification is caused by "something else".
Rawls, however, notes that Chapter 8 seems to contradict this obvious conclusion, by ignoring the inconvenient correlation between climate and cosmic rays, assuming that most of the changes are anthropogenic.
The New Scientist rebuttal of Rawls quotes extensively the comments of Joanna Haigh, a scientist at Imperial College London:
They're misunderstanding, either deliberately or otherwise, what that sentence is meant to say," says solar expert Joanna Haigh of Imperial College London.
Haigh says that if Rawls had read a bit further, he would have realised that the report goes on to largely dismiss the evidence that cosmic rays have a significant effect. "They conclude there's very little evidence that it has any effect," she says.
Fine. So it's "something else" causing the correlation between climate and cosmic rays then?
Well, New Scientist isn't saying. The "many empirical relationships" discussed in Chapter 7 are never addressed. We only hear more from Prof Haigh on the impossibility of the cosmic ray/cloud effect being responsible.
So we have a mystery. But more importantly we have a contradiction at the heart of the report that needs to be addressed.