The fourth assessment report of the Intergovernmental Panel on Climate Change was released in 2007. It's a long, complex document. But now there's an online guide to help you dig deeper into the science. It includes links to the primary literature cited in the reports, data on the journal cited (titles and numbers of citations), and data on authors cited in the reports.
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The guide is not for the faint of heart. It's for those who really want to dig into the science, but it's great to have this resource available.
If you're interested in a shorter version, take a look at the Synthesis Report for Policymakers.