not only is the signatories’ list full of climatists and environmentalists, it includes;
John P. Holdren, Ph.D.
Teresa and John Heinz Professor of Environmental Policy of Environmental Science,
Harvard University
https://not-binary.org/statement/
there are 33 names with Environmental in their description.
also:
Allison Crimmins, Environmental Scientist in Climate Change, U.S. Environmental Protection Agency