I recently discovered this little sticker on a paper towel dispenser in a toilet in New York:

It seems to work:

“Testing shows a “These Come From Trees” sticker on a paper towel dispenser reduces paper towel consumption by ~15%”
official website

It worked for me too, I didn’t use one of the paper towels and decided to let the air do the work. I ordered the large sticker pack, so be aware fast food restaurants and shared flat parties.
Please spread the project, and get a bunch of stickers for your neighborhood!