IPCC digital references
Some of the IPCC AR5 reports were written in LaTeX, some in MS Word. You will not be able to get the .bib files for those reports written using MS Word because Word does not use BibTeX.
Working Group I did use LaTeX, and you can get the .bib files for their report, on a chapter by chapter basis, here.
Working Group II apparently used Word, but they have released a set of bibliographies in both .csv and .xml format. I used &quot;apparently&quot; because I am getting errors galore for any page under ipcc-wg2.org. Apparently IPCC Working Group II has not updated their subscription, and some expletive deleted online gambling company has bought rights to that domain.