No one's ever completely broken. It's just a matter of how much has to fall apart before the ember of life is exposed to air.
I think people become environmentalists through experiences of beauty and grief. There was that pond that you visited when you were a child, and there were frogs and turtles. You go back there and it's dead now. The forest you went to, now there are bulldozers, now it's a strip mall. These experiences of beauty followed by grief affect us more than learning that CO2 levels are now 400 parts per million.
I am certainly not proposing that we wait passively for the people in power to change their minds. I think we need to be confrontational, to expose the truth in ways that are uncomfortable and that, yes, require courage. What I caution against is using hateful rhetoric to inspire action, and I see a lot of that today. We strengthen the underlying field of hatred, dehumanization, and conquest. It certainly doesn't engage what allows people to do courageous things and to commit deeply, which is the experience of beauty, love, grief.