Signatories are approved for inclusion in the Petition Project list if they have obtained formal educational degrees at the level of Bachelor of Science or higher in appropriate scientific fields. The petition has been circulated only in the United States.

The current list of 31,072 petition signers includes 9,021 PhD; 6,961 MS; 2,240 MD and DVM; and 12,850 BS or equivalent academic degrees. Most of the MD and DVM signers also have underlying degrees in basic science.

All of the listed signers have formal educations in fields of specialization that suitably qualify them to evaluate the research data related to the petition statement. Many of the signers currently work in climatological, meteorological, atmospheric, environmental, geophysical, astronomical, and biological fields directly involved in the climate change controversy.

The Petition Project classifies petition signers on the basis of their formal academic training. Scientists often pursue specialized fields of endeavor that are different from their formal education, but their underlying training can be applied to any scientific field in which they become interested.