"But the trees used to cut that poster and the glue used to put it up, along with the lighting needed to make it visible at a distance would incur unforgiveable costs on this planet..."

It IS a poster with a backlight that was already there.

This isn't BP throwing out a million dollar PR campaign to improve their image after polluting the ocean, this is a university putting out a PSA to drum interest about sustainable ways of using our digital devices.

They printed a poster and rented an illuminated poster board that was already there to do so. It's the same contradiction as using a diesel train to attend Friday for Future's rally. Sometimes you have to just have to use the most practical medium to get your message out