There are 4 main reasons for denying the global warming problem, ranking from the worst:
1. Those who give a fuck. Because they have not that long time left, or no children.
2. Money - Either they will lose money on enviromental improvements or they can't afford to make it better.
3. Those scared to face the through. Its a common known pshycological behaviour, to ignore it than face it, because it makes them feel better.
4. Those who argue, just because it please them to argue. Internet is perfect for that, including GFY.
So... shut up, face it, and do what u're supposed to do
PS! The 2nd could be the first, but I think its all about starting with ourself