Grist (an environmentalism web magazine) just posted a video about the impact on shaving. It's not long, it's not sophisticated, but it pretty much recommends that everyone switch to a straight. (DEs aren't even mentioned, for some reason.)
Ask Umbra’s video advice on shaving | Grist
Expect a flood (okay, a trickle) of environmental whackos any day now.
-Scott. (is a whacko)