A quick review of the cosmic ray / climate link.
Is 20th century global warming due to anthropogenic sources (i.e., greenhouse gasses) or natural variability? Find out here.
On long time scales, it appears that our journey through the Milky Way is responsible for large climate variations. Each time we pass through spiral arms of the galaxy, we witness a higher flux of cosmic rays, which in turn reduce the global temperature. Read more about the effect and the evidence in this article.