Well, I don’t know about “environazis”, but I’ve discussed the subject with many an otherwise nice enough person who is a believer in AGW (as a primary climate driver). I just direct them to this:
http://en.wikipedia.org/wiki/Ice_age#mediaviewer/File:Vostok_Petit_data.svg
and this:
http://en.wikipedia.org/wiki/Ice_age#mediaviewer/File:Five_Myr_Climate_Change.svg
and then ask them if humans were responsible. That usually quiets them.
I can’t get the graphs to post — maybe they are blocked now?