They won't listen. They have their heads too deeply buried. I sent them a song from Monty Python's "The Meaning of Life"; happy, joyful and sung just before a building sailed off the edge of a flat Earth.
I don't think any of them noticed. I wasn't surprised.
http://www.mwscomp.com/sounds/mp3/accntsh.mp3
Slowly, slowly enough people are taking their heads from the sand and starting to make a difference.