The online Urban Dictionary defines a warmenist as:
"Gullible, scientifically (sic) illiterate, unthinking acolyte and
zombie-fired propagandist of the Religion of Anthropogenic Global
Warming. One who takes direct orders from High Priest King of Idiocy, Albert J.
Gore. One who puts the "mental" in environmentalism. Historical
inheritors of those who believed that King Canute could hold back the
tides and that the wolf would eat the moon unless their first-born
daughter's virginity was sacrificed to the local shaman."
From the online Urban Dictionary :
"Somebody who believes in and tries to convince others of the notion of global warming."