I don't have the link handy, but not too long ago there was an interesting article about that posted to HN. Using reason doesn't actually work well with most people, most of the time.
People get emotionally attached to certain ideologies. It becomes part of their core identity, much like sports team affiliation.
It is often more effective to find emotional arguments instead. Show them pictures of smog in Bejing, for example. Or how the Marshal Islands are sinking under the ocean (well, the sea level is rising).
Annual Arctic ice cap melt increasing.
Bird migration ranges moving poleward, migration times moving winterward.
Animal and plant range moving poleward and upward.
Do you have an explanation for these facts other than climate change aka global warming? If not STFU. If you do, I'd love to hear it.
Trying to wave away statements by alleging ulterior motives or lack of knowledge only empowers the opposition. Debate them rationally, and you'll start to change more views.