If an alien invader with a face were attacking the earth, the difficulties that governments have getting populations to support wars on other humans would be multiplied a thousand fold.
The most common response to officials calling some petty foreign despot "a new Hitler" would shift from "yeah, right" to "who cares?" The people of the world would unite in common defense against the hostile alien.
If only it had a face. And what's a face anyway? Doctors can create faces now. You'd still love your loved ones if they lost their faces. And I hear there's a movie in which a guy falls in love with his faceless computer.
The point is that there is an alien invader attacking the earth. Its name is climate change. And Uncle Sam wants YOU to fight it, as does Uncle Boris and Aunt Hannah and Cousin Juan and Brother Feng. The whole family is in agreement on this one, and we are a family now all of a sudden...