I always suggest Spencer Weart's 2008 history of climate change, published by the Center for History of Physics of the American Institute of Physics at http://w

I always suggest Spencer Weart's 2008 history of climate change, published by the Center for History of Physics of the American Institute of Physics at http://www.aip.org/history/climate/index.htm http://www.aip.org/history/climate/index.htm (also available as a book). It provides a lot of technical detail and shows how, for example, climate models were improved over time. Reading it resolved the question for me: global warming's theory and observations developed over time, much like any other scientific field.