We're trying to find better frameworks, and one of the ones we've been considering is not to worry at all about talking about the size of our users' footprint, but rather to talk about the benefits of various types of changes in consumption if they were widely adopted. That way the negative situation presented isn't some confusing, oversized and hypothetical scenario, but simply the one we think is happening; and the benefits of one's changes aren't hypothetical, but potentially part of some larger (if unlikely) movement.
We're looking for the best way of presenting information about this issue and the benefits of actions people can take. If you or anyone reading this have any ideas about you'd want to see someone do this, we'd love to hear them.