Nick Moran, who made the above graph, disses the notion that the planet benefits from iPads:
[M]ost eReaders are used for only two years before being discarded, replaced, lost or broken. That eReader, then, accounts for an initial carbon footprint 200-250% greater than your typical household library, and it increases every time you get a new eReader for Christmas, or every time the latest Apple Keynote lights a fire in your wallet. … If you live in a household with multiple eReaders — say, one for your husband and one for your daughter, too — your family’s carbon emissions are more than 600-750% higher per year than they would be if you invested in a bunch of bookshelves or, better yet, a library card.
NatGeo pushes back:
The amount of paper used for books in one year was estimated at 1.5 million metric tons, and each book produced gave off an estimated 8.85 pounds of carbon dioxide. Study groups have found that the carbon released from eBooks is offset after people read more than 14 eBooks. For the life cycle of a device for reading books, the carbon emitted is offset after the first year.