[mturmon]

Solar irradiance variations amount to a bit less than 0.1% over the solar cycle. It used to be thought solar-cycle variations (the 11-year period) could be a significant contributor to climate change.

This turned out not to be the case...that was pretty much known by the early 2000s.

Other irradiance variations, due to orbital variations called Milankovich cycles, happening in the 10,000's of year range, do appear to influence climate. Of course, the extremes we're seeing now are not on the 10,000-year time scale.