One question: you discount orbital insolation? Does this mean you’re rejecting Milanhovich cycles as a driver of climate?
No, not at all. That’s great.
I believe the classic Milankovich theory is not now the preferred orbital driver (there are also dust plane effects I believe), but such a thing is not relevant in the short term of the next 5 centuries or so and, although interested as basic science, it is not presently relevant to policy and the recent climatic record.
If you want better references on solar influence on the “global warming is caused significantly by cosmic rays” hypothesis I recommend Nir Shaviv as a serious scientist, although the following must also be considered:
Certainly orbital effects and perhaps some large scale galactic events like cosmic rays can be important over long geologic timescales. It seems unlikely to be important in the short run, as in 500 years, whereas the GHG alteration by humans is both that rapid and of sufficient magnitude to worry about.
