Because admitting climate change is real means effort and change.

• Effort, because those responsible for causing climate change need to be deposed. Nobody will make that change happen if their sofa is so comfy and there aren't any problems that personally effect them.
• Change, because deposing those responsible for climate change also means getting rid of the system that enables them. If the solution to climate change were a drop-in replacement to something that requires no change whatsoever in daily norms it would have a lot more support.