Foukai, Frohlich, Spruit, Wigley, 2006. "Variations in solar luminosity and their effect on the Earth's climate," Nature 443 (issue 1038): Existing literature suggests that the evidence is solidly on the side of solar brightness having relatively little effect on global climate, with little likelihood of significant shifts in solar output over long periods of time.   "...brightening of the Sun is unlikely to have had a significant influence on global warming since the seventeenth century."
See list of peer-evaluated articles consulted in this review.

http://www.mpa-garching.mpg.de/mpa/publications/preprints/pp2006/MPA2001.pdf