Dr. Vincent Courtillot is a professor of geophysics at the University Paris-Diderot and Chair of paleomagnetism and geodynamics of the Institut Universitaire de France. In the recent lecture below he explains how solar cycles control the climate by influence on cloud formation (the cosmic ray theory of Svensmark et al) and via influence on ocean oscillations and length of day. Dr. Courtillot notes that IPCC climate computer models do not correlate with observations and that temperature trends vary substantially between North America and Europe (which is contrary to IPCC computer model predictions). He also notes that while the total solar irradiance (TSI) only varies by about .1% over a solar cycle, the solar UV varies by about 10% and that secondary effects on cloud formation may vary up to 30% over solar cycles. The IPCC computer models dismiss the role of the sun by only considering the small variations of the TSI and ignore the large changes in the most energetic and influential part of the solar spectrum - the ultraviolet.
Powerpoint slides from the lecture