Don't worry, Ana. The people behind the Doomsday Clock have an agenda. The point is to frighten you into cooperation with that agenda. OK, that's sort of terrifying in its own right, but... BIG DEEP BREATH.
Governments aside, if you give people the tools to change (and stop jamming it down their throats), most people will change. They're more likely to do it if it's a choice, and one that can be made without a whole lot of painful forced adjustments very quickly.
So what do you do?? Make every effort you can to live as conservatively (in terms of resources, not politics) as you can. If you're a young, single female (or male, for that matter) your choices are just about limitless. Show others (stodgy old materialists like my hubby) that it can be done, that it can be fun, that it can be comfortable and beautiful. TEACH.
As far as us destroying the Earth goes-- Honey, BREATHE. Gaia was around before we were ever thought of, and she'll be around long after we're gone. If we get too far out of line, we'll turn on each other and destroy, not the Earth, but the human race. We'll kill ourselves off until we learn to live in balance...
...or we'll kill ourselves off to below a sustainable population base and be gone. In our absence, the Earth will recover and go merrily on until a giant asteroid smashes it to bits or the Sun goes supernova.
She'll shake us off like a dog shaking off fleas. I promise.
Now, personally, I AM a believer in ACC. I think we're screwing it up, and screwing ourselves in the process, with the good old American Material Fantasy and all the rest of it. I like to see us STOP.
But I don't trust any government to MAKE us stop. They're human too, they have power-hungry, greedy ulterior motives. Our leaders aren't pure and good-- hell, they're not even leaders. It's going to have to be a CHOICE that people make, one person at a time.
Live the choice. Teach the Way. You can do this.
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"Alas, our dried voices when we whisper together are quiet and meaningless, as wind in dry grass, or rats' feet over broken glass in our dry cellar." --TS Eliot, "The Hollow Men"