Slate considers the canard that e-book readers are way more bad for the environment than real books.

Apple's iPad generates 130 kg of carbon dioxide equivalents during its lifetime, according to company estimates. Amazon has not released numbers for the Kindle, but independent analysts put it at 168 kg. Those analyses do not indicate how much additional carbon is generated per book read (as a result of the energy required to host the e-bookstore's servers and power the screen while you read), but they do include the full cost of manufacture, which likely accounts for the lion's share of emissions. (The iPad uses just three watts of electricity while you're reading, far less than most light bulbs.) If we can trust those numbers, then, the iPad pays for its CO2 emissions about one third-of the way through your 18th book. You'd need to get halfway into your 23rd book on Kindle to get out of the environmental red.

There are many cases you can make for books as physical objects, but saying they're greener doesn't quite work. This game is pointless, anyway: The environment would be better off if we stopped making books and iPads. And my bookshelves serve as insulation—keeping heat in and keeping sound out—and that's an environmental benefit that iPads can't compete with on any meaningful level.