The reduced radiative forcing estimate comes from a re-evaluation of the long - term change in solar irradiance since 1610 (the Maunder Minimum) based upon: a new reconstruction using a model of solar magnetic fl ux variations that does not invoke geomagnetic, cosmogenic or stellar proxies; improved understanding of recent solar variations and their relationship to physical processes; and re-evaluation of the variations of Sunlike stars. (realclimate.org)
Climate scientists sometimes refer to the effects of chaos as intrinsic or unforced variability: the unpredictable changes that arise from the dynamic interactions between the oceans and atmosphere rather than being a result of «forcings» such as changes in solar irradiance or greenhouse gases. (newscientist.com)
For the period after 1974,... there is no evidence for any non-magnetic change in the solar irradiance on time scales longer than about a day.» (realclimate.org)