A lot of sources are accessible, as well as the data:

http://www.realclimate.org/index.php/data-sources/?wpmp_tp=1

The models are all numerical simulations. But even if you are skilled in numerical calculations you'd need a lot of energy to learn and understand the domain too.

Here's one university elementary-introduction-level course about that:

http://www.cs.toronto.edu/~sme/CSC2602/

and one book with the real formulas:

http://www.climate.unibe.ch/~stocker/papers/stocker14icm.pdf