There is a very good treatment of the solar variability issue here:

http://www.skepticalscience.com/solar-activity-sunspots-global-warming.htm

I mean here.

It says (in part):
"The correlation between sun and climate ended in the 70's when the modern global warming trend began.

As supplier of almost all the energy in Earth's climate, the sun certainly has a strong influence on climate change. Consequently there have been many studies examining the link between solar variations and global temperatures.

The correlation between solar activity and temperature
The most commonly cited study by skeptics is a study by scientists from Finland and Germany that finds the sun has been more active in the last 60 years than anytime in the past 1150 years (Usoskin 2005). They also found temperatures closely correlate to solar activity.

However, a crucial finding of the study was the correlation between solar activity and temperature ended around 1975. At that point, temperatures rose while solar activity stayed level. This led them to conclude "during these last 30 years the solar total irradiance, solar UV irradiance and cosmic ray flux has not shown any significant secular trend, so that at least this most recent warming episode must have another source."

In other words, the study most quoted by skeptics actually concluded the sun can't be causing global warming. Ironically, the evidence that establishes the sun's close correlation with the Earth's temperature in the past also establishes it's blamelessness for global warming today."