Skeptical Science Studies
Psychology Student and Climate Activist behind the fraudulently named and often discredited Skeptical Science blog, John Cook, did a couple of "Studies" to try to prove the 97% consensus.
- 2013 Cook selected 11,944 abstracts of papers, from pro-AGW journals, then cherry picked 64 papers for their use of sensationalist terms (like "Global Warming"), and found that 63 of those 64 agreed that "most" of the warming was from man: that's where his 97% number came from.
- No credible author, scientist or statistician could look at the methodology and not scoff. Quickly Director of the Center for Climatic Research at University of Delaware, David Legates, did a peer reviewed rejoinder that detailed many of the errors in Cook's methodology, including showing that 23 of the 63 paper’s authors disagreed with Cook’s conclusions that they supported Climate Consensus. Resulting in 41 of 11,944 abstracts agreeing with Global Warming (a 0.3% consensus, not 97%). Thousands of FakeNews sites cite Cook and 97% anyway, without mentioning Legates rebuttal.
- 2016 Cook decided to double-down on his fraud by doing a synthesis study, of adding up the totals of his, Oreskes, Doran, Anderegg studies together: ignoring all of those studies were discredited for the same methodological flaws of his 2013 Study. But now FakeNews outlets could more easily cite his 2016 "study" without mentioning Legates refutation, and only the truly curious would discover that all the studies that made up the 2016 Cook study had been discredited.
2016 Consensus on Consensus -- Synthesis Study - Cook, et al
This study seems to imply that combining enough of disproven studies together, will somehow results in a better conclusion: ignoring the garbage-in = garbage out theorem, or that all the older studies this one is based on, have been discredited (Cook, Oreskes, Doran, Anderegg). Worst of all is evidence that Cook was intentionally omitting evidence (between draft and release), and he then tried to have evidence of that omission removed from Internet archives (to hide what he was doing): proving intent of malice/knowingly distorting results. It's statistical nonsense to show popularity, and not validity -- and will be ignored by anyone with a clue, but it'll get repeated by the media or the participants as proof of something.
2013 Cook paper
"Quantifying the consensus on anthropogenic global warming in the scientific literature”, published in a peer reviewed journal, "Environmental Research Letters”.
This is the most commonly quoted source of the 97% myth today, because that’s the most “reputable” citation they have, before Cook, there was even shoddier “science” to get the 97%. Which is pretty embarassing, since Cook 2013 isn’t really science at all.
John Cook is a climate activist who claims to be a "post-doctoral student", but lacks a degree in Climate Science (he has a B.S. in Cognitive Psychology). He is behind the oft-criticized and fraudulently named Skeptical Science blog, which is dedicated to the opposite of skepticism and driving home the consensus, and obfuscating any factual problems or questions the Church of Climatology, to the point where has a known history of deleting posts of real Climate Scientists who refuted many of his claims. It’s a propaganda site, not a science site, but he tries to throw enough science in (in fragments), while dodging the key arguments, to flim-flam the gullible. While creating this study, he was caught in forums talking about how he was going to “porno” the numbers (his words) to make the study sensational for the Press. And his“study” did that. So we know where his biases are.
Methodology: Cook decided to “prove" the consensus by self selecting 11,944 abstracts of papers, from Journals that were filtering for pro-AGW bias to begin with (from Climate Journals known in the Climate Gate controversy), then he filtered that subset down to 4,014 papers which used terms like “Global Warming” (using sensational terms), which he further filtered to 64 papers (.3%) that explicitly concluded that “most of the warming (>50%) was caused by man”. Of those 64, 63 agreed with his view, and hence the 97% number. 23 of the paper’s authors came forward later and disagreed with Cook’s conclusions (saying he misrepresented their work), so he actually only had 41 papers that fit his criteria, while 10x as many (3% of all papers) claimed there was no human factor in the warming, but they had been filtered out.
- >10x as many directly disagree with warming consensus as agree with it
- 99.7% of Climate Papers sampled had no position or a negative positions on AGW theory, and definitely did not achieve the IPCC standards of “most” or “>90%"
- Only .3% of Climate Papers agree with the IPCC that “most of the warming” was caused by man
- But by the Press/Cook’s reasoning, “97% of the 64 papers we cherry picked to agree with us, agree with us”, if you ignore 35% of those authors disagree with his assessment, and the other 11,880 papers we filtered out 
2013 Legates did a peer reviewed rebuttal paper of 2013 Cook
"Climate Consensus and ‘Misinformation" a rejoiner to Agnotoloy, Scientific Consensus and the Learning of Climate Change” by David. R. Legates, and many others. Published in Springer Scientific.
This explained all these falsehoods, and is generally accepted as disproving Cook’s paper. But the media and climate advocates quote freely from Cook, and ignore Legates rebuttal. Hence the "97%” myth.
- 2013 Refutation: