Okay, so Sustainable Graphic Design doesn't exist. We can look at this from a couple of different angles.

If we keep the definition of "sustainable graphic design" as design for the welfare of all life (or maybe maintaining spaceship earth?) then there are some things to think about in this vein...

1. The status quo.

If graphic design maintains the status quo, really in any way, then it just isn't sustainable. We can't help promote or maintain fossil fuels, inefficient energy infrastructure,