[dr_who]

So their affects on total emitted light are partially canceled.

In terms of electromagnetic radiation at least, I wouldn't expect them to have any measureable effect on the ~1300 W/m^2 we get from the sun, given how much surface area that the sun has. And what's so special about UV? As for subatomic particles that probably mostly bombard the poles, it would be interesting to know how that affects polar weather patterns or whether radiation in the upper reaches of the atmosphere have much of relevance to the lower atmosphere which I guess is what we're really concerned about.

[justa-hairyape]

And what's so special about UV?

Very important. It affects the Ozone Layer for starters. Another NASA scare born from ignorance. A new study also found that it affects the temperature of Earth's outer atmosphere, which ends up causing the outer atmosphere to expand and shrink in volume.