And I do use the crimes against humanity line quite a lot. Problem is, a crime is a "socialized" label.
Slavery, genocide, etc may have been moral atrocities all along but it's a relatively recent thing to call them crimes. We can work to make ecocide a crime, but crimes are defined by authorities. Authorities are established to keep power status quos, and therefore trail power shifts, not lead them.
There's been great pieces on Medium lately regarding global warming; including discussions on mindset a and communication and some short climate fiction pieces for those so inclined.