evidence: The best way to understand how 20th century solar changes affected the climate system is with global climate models. [...] Using the same physics, climate models are able to include observed changes in direct solar forcing over the 20th century. To do this, they use a number of different estimates of solar forcing from different research teams. [...] Some of the patterns of change associated with solar forcing are similar to greenhouse gas driven changes, such as more rapid warming of the Arctic. However when the pace of change is also factored in, solar changes have been far too small to explain the dramatic warming of the Arctic that has been observed.