n. A person who believes that the current global warming trend is the result of man-made factors.
2009
The road to Copenhagen has proved to be a rocky one. This past fortnight, ahead of the climate-change summit that starts in the Danish capital on Monday, the air has been thick with pejorative cries of "warmist" and "denier". The former are those who subscribe to the view that the increase in the Earth's temperature in recent decades is the fault of man's profligate use of the planet's fossil fuels; the latter may or may not dispute that the temperature is rising, or that it is in some way man's fault, but are certainly not convinced that dramatic remedial action is required.
2009
Some kind of deal is expected because while most countries accept that the earth is getting warmer, the debate as to what extent it will change our climate and impact on our lives has not been settled. 'Warmists' (those who believe) and 'deniers' largely agree on the basic science.
1989 (earliest)
Among climatologists, global warming is just one scenario for the unusual atmospheric changes that have been observed throughout the world. Those who accept the global-warming theory are said to take the warmist position. … To complicate the issue, other climatologists believe both warmists and coldists fail to take into account the possibility that warming and cooling factors could balance each other, resulting in a more or less static climate.
As the earliest citation shows, the term warmist started out its linguistic career as an essentially neutral label for scientists with a particular point of view (i.e., that the globe is gradually getting warmer). That began to change about 10 years ago, and now warmist is used almost exclusively as a pejorative (hence the term's inclusion in Word Spy's insults category), either directly (by a global warming opponent — a coolist or denier) or indirectly (by a neutral observer tsk-tsking at all the epithetic bombs being tossed back and forth in the ongoing global warming debate).