> Registered to present their own opinion.

You don't have to register as a registered lobbyist in USA to present your own opinion. You have to register as a registered lobbyist to represent somebody's else opinion.

The vast majority of registered lobbyists in the USA are paid professionals, usually from the legal field. Several major law companies run large lobbyist for hire departments.

Now Michael Shellenberger may be one of the pro-bono lobbyists (admittedly I haven't yet found out either way), but this would put him in the minority of registered lobbyists in the USA.

I will note that he was at one point a paid lobbyist for Hugo Chavez. Was he presenting his own opinion then?