So, Karawynn Long says "97% of world scientists agree that human-caused climate change is increasing." The article she linked to quotes someone as saying, "97 percent of American scientists say that climate change is happening." The article doesn't link to a source for that, but it seems to be a reference to a 2009 poll of scientists (see http://articles.cnn.com/2009-01-19/world/eco.globalwarmingsurvey_1_global-warming-climate-science-human-activity?_s=PM:WORLD
) in the American Geological Institute's Directory of Geoscience Departments (Keane & Martinez), in which only 82% of the scientists polled agreed that human activity had been a significant factor in changing global temperature. The 97% comes from the subset of the poll consisting of climatologists who are active publishers in climate research. The survey invitation was sent out to over 10,000 scientists. The response rate was about 30%, but there was no effort to determine whether the responding sample was representative of the whole group. Nor is there evidence that the scientists listed in the directory are representative of all geoscientists, let along all scientists in the world.
So, one can accurately claim that 97% of climatologists who responded to a web poll and are actively engaged in publishing climate research (a total of 79 people out of the 10000 invited to participate in the survey) agree that human-caused climate change is significant. How one gets from there to "97% of world scientists agree that human-caused climate change is increasing" is left as an exercise for the reader.
Just doing my part to set the record straight with, you know, verifiable facts.