The IPCC full reports are probably the place to start.

However, before embarking on your own analysis, you should consider what questions you're trying to answer and how to avoid misleading yourself. There are two very important and extremely complex areas: proxies and forcing.

Proxies are the use of data other than temperature measurements to infer temperature, such as tree rings and ice cores.

Forcing is the second-order effects of more CO2 such as causing more water evaporation - whic is itself a greenhouse gas.