Legislation has to be passed for action to be taken. And don't get me started on legislation not getting passed.
First of all, no, legislation doesn't have to be passed in order to get change to happen.
And second, your response begs the question. If there was less insult and more focus on approaching things in a way people could rally behind, there could be more legislation. But people -- even people who claim to want the government to take action in response to global warming -- block legislation for political purposes.
So my point stands -- how about less focus on people who deny climate change and more focus on things which would be good policy even for those who won't agree that man-made global warming is something to be alarmed about.
Do people want action or don't they? If they do, then acknowledge that much of what has been tried so far hasn't worked very well and make adjustments.