1. It's irreversible.
2. Change is inherently bad.
3. Humans are incapable of adapting.
We don't need all of these assumptions to be wrong. If just one of them is wrong, then we aren't "doomed."
We have a long track record of being terrible at predicting the future. We also routinely predict negative outcomes and then move on to a new reason to hand wring when our prediction turns out to be wrong.
When the Kuwaiti oil wells were lit on fire, it was predicted they would burn for years and be a global environmental catastrophe. When crack teams converged on Kuwait, invented new techniques and put them out in six months, this was not celebrated. It was a minor footnote in more dramatic stories.
Y2K was supposed to cause a global financial meltdown. We look back on that and remember the folks who prepped for the Y2K Apocalypse as loonies. No one (but me)* gets up every day and goes "Thank God! We aren't living in the Y2K Post Apocalypse and my ATM still works!"
We certainly need to work on resolving some things. We also are working on it.
If you're scared, then give up your car, eat less meat, etc. You can be part of the problem or part of the solution. Your choice.
* Technically, not even me. I only do that occasionally, not daily.