Solar blow to low cloud could be warming planet
And below is how the IPCC evaluated it. One thing that I think is of interest when you read this (if you choose to) is that it shows how much research is considered by the scientific arm of the IPCC. Many of the criticisms of the IPCC process are of the "politicization" of the science findings when they attempt to translate them into policy recommendations. I agree with much of that criticism. But I also think that the IPCC does a pretty good job of evaluating the state of climate science. Where they've gone overboard is in not stating maximum likelihood parameters for their predictive models, and that allows the media to run wild with the worst-case (and usually quite implausible) scenarios.
I believe the IPCC accepts the hockey stick temperature record (temperature is flat over the last 1000 years until about 1900) and ignores the medieval warm period and the little ice age as supposedly not being representative of the globe as a whole. If they recognized these earlier temperature excursions, they would have to admit that things other than greenhouse gases affect temperature, namely variation in solar radiation.
Prof. Lindzen of MIT, who participated in the IPCC study, described the IPCC process as follows,
"The preparation of the report, itself, was subject to pressure. There were usually several people working on every few pages. Naturally there were disagreements, but these were usually hammered out in a civilized manner. However, throughout the drafting sessions, IPCC 'coordinators' would go around insisting that criticisms of models be toned down, and that 'motherhood' statements be inserted to the effect that models might still be correct despite the cited faults. Refusals were usually met with ad hominem attacks. I personally witnessed coauthors forced to assert their 'green' credentials in defense of their statements."
This sounds like a debate on evolution chaired by a fundamentalist church.
Your link to the IPCC discussion of the correlation between solar activity and global temperature actually referred to discussions they had about how the sun might influence cloud cover. Cloud cover may indeed be one of the mechanisms at work here, but perhaps not the only one. Nowhere did I see where the IPCC refuted the correlation between solar activity and global temperature. They are just finding fault with theories about how the sun could cause this to happen. That is not the same as refuting that it happens.
Energy balance calculations show that solar radiation explains most of the earth's temperature level. When variations in the sun's behavior correlate with global temperatures for hundreds of years without any need to invoke soot, aerosol particles, volcanic eruptions, el Ninos, etc., it is a strong argument in favor of the sun being the main cause of global warming.
Some wags have suggested that human activity on earth must be causing the corresponding variations in solar behavior. That makes as much sense as attributing the bulk of global temperature variations to greenhouse gas.