> professional climate deniers
Koonin does not deny that the climate is warming, or that humans play a role in it.
Calling him a "professional climate denier" is rather disingenuous, especially if you have not read what he has to say, in depth.
Since you responded though, why would you not want to learn more about the topic, especially from a renown scientist who literally wrote the book on theoretical computer modeling of physical systems (like climate)?