According to the latest IPCC report, AR5, the influence of the sun on our climate since pre-industrial times, in terms of radiative forcing, is very small compared to the effect of greenhouse gases.
According to some more skeptical scientists such a small solar influence is counterintuitive. The Little Ice Age, the period roughly from 1350 to 1850, in which winters on the Northern Hemisphere could be severe and glaciers advanced, coincided with the so-called Maunder Minimum, a period of supposedly low solar activity. In their eyes, the sun therefore still is a serious candidate to also explain a substantial part of the warming since pre-industrial times.