It's already too late. There has been permanent, irreparable damage to the planet, as a direct result of humanity. Denying that is ludicrous.

We are in the midst of a mass extinction that if we were to end immediately, would still be one of the earth's biggest catastrophes, in all of its billions of years of existence. Think about that, if all of humanity were to cease to exist all at once, the damage has already been done. It'd be geological record that we destroyed a significant amount of biodiversity in a few decades. 

And we just keep driving the planet to the brink. The future of humanity is really, really, really, really bleak.