The main environmental costs of buying books relate to shipping and transportation. Fuel consumption, packaging, greenhouse gas emissions, air pollutants, and hazardous waste are byproducts of moving things from here to there. Therefore, any actions you can take to reduce miles traveled—for yourself or your book—as well as the impact of the transport mode, will result in a more eco-friendly book purchase.

According to estimates in a study by professors at Carnegie Mellon, the average book sold in a bookstore travels more than 1,500 miles before it reaches its final destination—on a bookshelf, a nightstand, or next to the commode in the "reading" room.

The full accounting of miles traveled includes: transportation from the printer to a national warehouse, the trip from the national warehouse to regional distribution centers, followed by the shipment from the distribution center to the retail store. The customers then travels from their homes to the bookstore, buy the book, and drive home with it.

Because online sellers streamline their delivery processes and eliminate the need for the customer to drive to a retail outlet, books purchased online might travel an average of only 1,000 miles from publisher to consumer. However, most of the environmental advantages gained from saving these 500 miles are negated by the cardboard box and packaging used to ship online orders.

If online orders are shipped exclusively via ground transportation, then books purchased online are slightly more eco-friendly than books bought at a bookstore (assuming you drove two miles to get there—or combined a 10-mile shopping trip with four other stops). But once you get involved with airfreight, you may as well drive an SUV to the mall. Online shipments delivered via airfreight are the least environmentally friendly of all options.

If you’re determined to order online, or are already headed for the bookstore, keep in mind that buying used books is always preferred to buying new books. And because local used bookstores may stock locally collected books, getting a used book from a local bookstore is likely more eco-friendly than buying from an online bookseller.

However, because the environmental costs of driving far outweigh the costs of new book production, it’s actually better to avoid the drive and buy a new book than to spend fuel to buy a used one.

Of course the most eco-friendly book-buyer would be the one who walks, bikes, or takes public transit to their local bookstore to buy a used book—but if that were one of the choices, we couldn’t call it an Eco-Genius Challenge.