The Sun, or rather the amount and character of solar radiance that intersects our planet, is the primary Driver of Climate, how our surface compostions and systems interact with the climate drivers are the various forcing factors that together, in concert, determine whether that energy exits the system with little delay leaving less energy in our planet's environment or lingers in our system adding more energy into our planet's surface environment.
Another and apparently very significant factor is how much of the TSI is reflected away before it gets to the surface.
Well, technically the "surface" starts at the top of the atmosphere; atmospheric composition results in the first interaction for impinging solar radiances.
Indeed, they never have been considered so. Clouds on the daylit face of the Earth tend to reflect significant amounts of Sunlight back up through the atmosphere, whereas clouds on the night face of the planet tend to absorb and disperse even more of the emitted solid and liquid surface radiations. One adds a cooling effect, the other adds a warming effect.
The charlatans at CERN postulated that cosmic rays might affect cloud formation and demonstrated that this effect might have as heavy an influence on our climate as CO2.
Actually, though this is an oft considered proposition, many researchers around the globe have looked very hard for direct and indirect connections, so far without any compelling evidence of at connection. The basic concept is not unreasonable, but in real world application, it just doesn't seem to work that way. Heavy levels of cosmic rays do seem to produce a lot of charged particle species in the atmosphere, unfortunately, these small clumps of charged particles dissipate before they can interact with the other atmospheric constituents and grow to a size where they can actually form viable cloud condensation nuclei. LIndzen's Iris theory is intriguing, it is simply without compelling evidentiary support.
Whatever the actual causes and effects, the system seems to be too complex for our current understanding of the science to predict.
To predict weather, yeah, I'd tend to agree. I doubt that we'll ever get weather analysis to the point where you aren't talking about percentages of likelihood. Climate however, is a bit different. Just as we can't accurate predict precisely where an atom of Nitrogen in a balloon is going to be ten minutes from the time we identify it (weather), but we can tell you some basic characteristics about how all of the nitrogen in the balloon is going to generally react when we heat or cool the gas, compress or expand the balloon, or add other gases into the balloon (climate).
