Carbon cartel?
Carbonistas?
CarboƱeros?
Carboratchiks?
or more obscurely (yeah right) the tetravalents.
Carbonari has already been taken. Hmmm...
From Reuters:
A growing "carbon army" of environmentalists, bankers and investors has seized on official backing last week for major public spending announced in Britain and the United States....MOREClassic Baptists and Bootleggers (three page PDF by the man who coined the term)
Update: A reader emails that CarboƱeros reminds her of the SUV Marge Simpson drove in the "Last Temptation of Krust" episode:
Canyonero