Problem: the number of humans grows constantly on a world of finite space.
Conclusion: eventually, resources will run out, and we will commit ecocide as we try to use technology to provide enough food, water, medicine, air, etc. for our population.
However, people don't want to hear about this. It requires too much thinking.
Solution: invent a symbol for it all called "global warming."
The problem with this is that it's the same strategy anti-drug workshops use. "You better not smoke pot, or you'll end up a homeless bum with a criminal record!"
First time they smoke and that does not happen, they'll assume it's safe.
Global warming proponents have been howling about imminent apocalypse for years, and so have desensitized their audience. This is because their main point is a political symbol, not a reasoned scientific view.