Support your planet, package handlers, and delivery man by going digital. I worked for a shipping company couple years back to pay for school and let me tell you, I would literally load up a half truck with 50 pound boxes of books. Now imagine the carbon footprint of that, not just the amount of trees that had to be cut down, but the emissions from the manufacturing of the paper, ink, glue that goes into the book. Then imagine the carbon emissions from the planes, semis, and delivery trucks that go into delivering that book to a bookstore or library or your home.
Libraries are funded from local and municipal taxes so you renting a book from them is not support, and honestly they do offer digital rentals of ebooks so please stop murdering the planet with your physical books. mmkay
You understand that the carbon footprint of a 20 mb book on your computer or the cloud is miniscule compared to physical book productions though, some data centers are actually carbon neutral too.