The list of 500 is available in this document.
The list is grouped by country and starts with:
SCIENTISTS AND PROFESSIONALS FROM BELGIUM
- Rob Lemeire, Publicist on Environmental and Climate Issues, ECD Ambassador
- Eric Blondeel, retired Civil Engineer.
- Emiel van Broekhoven, Emeritus Professor of Economics, University of Antwerp
- Christophe de Brouwer, MD, Honorary Professor of Environmental and Industrial
Toxicology, Former President of the School of Public Health at the Université Libre de
Bruxelles
- Christian Dierick, Lead Expert, Energy Technology Solutions
- Ferdinand Engelbeen, Former chemical process automation engineer, Akzo Nobel
Chemicals
- Samuel Furfari, Professor of Energy Geopolitics at the Free University of Brussels
- Georges Geuskens, Emertitus Professor of Chemistry, Free University of Brussels and
Expert Publicist on Climate Science
- Drieu Godefridi, PhD in Law, author of several books
- Jan Jacobs, Science Journalist Specializing in Climate and Energy Transition
- Raymond Koch, Retired Research director at Lab. Plasma Physics, RMA Brussels and
Fellow Lecturer at UMons.
- Henri A. Masson, Emeritus Professor Dynamic System Analysis and Data Mining,
University of Antwerp
- Ferdinand Meeus, Retired Research Scientist, IPCC expert Reviewer AR6
- Jean Meeus, Retired Meteorologist, Brussels Airport, Author of the Best Seller
Astronomical Algorithms
- Ernest Mund, Honorary Research Director, FNRS, Nuclear Engineering
- Bart Ooghe, Geologist & Geophysicist, Independent Scientist
- Jozef Verhulst, Author
- Jean van Vliet, Retired Specialist in Space Weather
- Appo van der Wiel, Senior Development Engineer
The most are from Italy: 113.
The letter uses the phrasing "more than 500 knowledgeable and experienced scientists and professionals in climate and related fields". Not all are "scientists" as per the title that the OP wrote. As seen above, one person is simply listed as being an "author" and another is listed as "PhD in Law, author of several books".