lukewarmist

Etymology

From lukewarm + -ist.

lukewarmist means A person who has an indifferent or unenthusiastic attitude. Lexicurio rates it Sui generis — a strength score of 87 out of 100.

noun

A person who has an indifferent or unenthusiastic attitude.
Synonym of lukewarmer (“one who believes that climate change is due to human activity but who does not think it is a serious problem”).