I'm sad and worried that I may not live long enough to see civilization collapse due to climate change
That's odd. Why would you want to live long enough to see civilization collapse?
I'm a complete environmentalist and I think it's my mission to die from climate change.
As an environmentalist you should be working to prevent climate change and the collapse of civilization. Wishing for the complete collapse of civilization is wrong due to the immeasurable suffering collapse would cause. You should learn to be more empathetic towards people and the sanctity of life.
It's the only way to stop climate change.
The purpose of stopping climate change is to save civilization. I understand the frustration with people, but wanting to see civilization destroyed is wrong. You should put that feeling aside and continue working to save the planet.