Ask HN: Objective books on anthropogenic climate change

I belong to a book discussion mini-club and one of the subjects we want to study this year is climate change.

I'd like to find some objective materials that deal with the scientific data rather than the politics, however most of the books I'm finding are written from presupposition, trying to prove or disprove something from the outset rather than rationally examining and discussing the data.

Any recommendations for non-partisan and objective books (or online sources)?