Originally Posted by Spaceman Spiff

With regards to whether or not fluctuations in cosmic ray flux (largely correlated with the solar cycle) has any significant impact on recent trends in global climate, see here and here and here.

The other issue is that the actual mechanism for forming clouds via cosmic ray interactions with Earth's atmosphere, what kinds of clouds are formed from such, and how these clouds would impact Earth's radiative energy budget (and on what time scale) remain speculative.