A number of critics of the petition questioned the scientific credentials and the authenticity of the names of the signatories.
In May 1998 the Seattle Times wrote:
“ Several environmental groups questioned some of the names in the petition. For instance: "Perry S. Mason", who was a legitimate scientist who shared the name of a TV character. Similarly, "Michael J. Fox", "Robert C. Byrd", and "John C. Grisham" were signatories with names shared with famous people. Geraldine Halliwell was added as: "Dr. Geri Halliwell" and "Dr. Halliwell." This name may have been contributed by a proxy trying to discredit the petition since Ms. Halliwell has never admitted to signing the petition.
Asked about the pop singer, Robinson said he was duped. The returned petition, one of thousands of mailings he sent out, identified her as having a degree in microbiology and living in Boston. "When we're getting thousands of signatures there's no way of filtering out a fake", he said.
In 2001, Scientific American reported:
“ Scientific American took a random sample of 30 of the 1,400 signatories claiming to hold a Ph.D. in a climate-related science. Of the 26 we were able to identify in various databases, 11 said they still agreed with the petition —- one was an active climate researcher, two others had relevant expertise, and eight signed based on an informal evaluation. Six said they would not sign the petition today, three did not remember any such petition, one had died, and five did not answer repeated messages. Crudely extrapolating, the petition supporters include a core of about 200 climate researchers – a respectable number, though rather a small fraction of the climatological community. ”
In a 2005 op-ed in the Hawaii Reporter, Todd Shelly wrote:
“ In less than 10 minutes of casual scanning, I found duplicate names (Did two Joe R. Eaglemans and two David Tompkins sign the petition, or were some individuals counted twice?), single names without even an initial (Biolchini), corporate names (Graybeal & Sayre, Inc. How does a business sign a petition?), and an apparently phony single name (Redwine, Ph.D.). These examples underscore a major weakness of the list: there is no way to check the authenticity of the names. Names are given, but no identifying information (e.g., institutional affiliation) is provided. Why the lack of transparency? ”
To the issue of duplicate names, the Global Warming Petition Project had responded:
“ Thousands of scientists have signed the petition more than once. These duplicates have been carefully removed from the petition list. The list contains many instances of scientists with closely similar and sometimes identical names, as is statistically expected in a list of this size, but these signers are different people, who live at different addresses, and usually have different fields of specialization. Primarily as a result of name and address variants, occasional duplicate names are found in the list. These are immediately removed.