The easiest way to learn about the science and physics of global warming is to read  Climate Change: Evidence & Causes from the Royal Society an the American Academy of Sciences. This short booklet, which can be downloaded free of charge, summarizes most of the science in a very accessible form.

The Guardian also devotes a lot of space to the issue of global warming. They also publish an ultimate climate change FAQ and an excellent page called Climate Consensus — the 97%.

There is also an excellent history of climate science available on the web.

We would also encourage you to read the report 2 degrees of separation from PwC. It is encouraging to see that commercial organizations and global corporation take the problem of climate change very seriously.