Late year I blogged about the habit of some AGW supporters using the term denier to denigrate their opponents. In that post I referred to the GCR hypothesis for global climate changed. In a nutshell it runs like this, GCR (Galactic Cosmic Rays) when present increase cloud formation, which reflects sunlight back into space before it get to earth, and this cools the planet. When GCR decrease, cloud formation drops and the Earth warms as more sunlight reaches the surface. The Solar magnetic field determines the amount of GCR reaching the Earth, so the solar magnetic field is a principle driver of climate changes on the planet.
The key here is cloud formation, a process not very well understood as the science not stands. The GCR theory is an outlier for cloud formation theory and as such the GCR aspect of global climate changes have been discounted by climatologist in general. (Note: I am not accusing people is hiding or ignoring evidence, some idea takes awhile to become accepted, provided the fact support them and they are falsifiable. To with look at the history of continental drift, once considered a crackpot idea.)
Well the GCR hypothesis for cloud formation has leapt over a major hurdle. The fine physicists at CERN have established with particle accelerators that GCR do play a major part in cloud formation. As current climate models all ignore GCR as a factor in cloud formation, and cloud formation is a critical element of climate modeling, the current models have the be redone. It is possible, perhaps even likely, that all of the climate change we have seen so far is due to increased GCR reaching the Earth as the solar cycle varies.