I like to compare climate change with fire insurance - most people have fire insurance on their house because they *really* don't think it's going to burn down. BUT, the financial risk is so great you can't afford to chance it and the cost of insurance isn't that great. Same with climate change - most of the world's scientists say there's something to worry about, so I say let's take out some insurance. Maybe it's a waste of money - but the consequences if the scientists are right are pretty dire, so it's worth insuring against it.
But unfortunately climate change deniers are not rational....