In 2004, Naomi Oreskes performed a survey of all peer reviewed abstracts on the subject "global climate change" published between 1993 and 2003. She surveyed the ISI Web of Science database, looking only at peer reviewed, scientific articles. The survey failed to find a single paper that rejected the consensus position that global warming over the past 50 years is predominantly anthropogenic. 75% of the papers agreed with the consensus position while 25% made no comment either way (eg - focused on methods or paleoclimate analysis).
Benny Peiser's rebuttal
Benny Peiser repeated Oreskes survey and claimed to have found 34 peer reviewed studies rejecting the consensus. However, an inspection of each of the 34 studies reveals most of them don't reject the consensus at all. The remaining articles in Peiser's list are editorials or letters, not peer-reviewed studies. Peiser has since retracted his criticism of Oreskes survey:
"Only [a] few abstracts explicitly reject or doubt the AGW (anthropogenic global warming) consensus which is why I have publicly withdrawn this point of my critique. [snip] I do not think anyone is questioning that we are in a period of global warming. Neither do I doubt that the overwhelming majority of climatologists is agreed that the current warming period is mostly due to human impact."