Books form an integral part of daily life, but few people are aware of the CO₂ emissions resulting from the manufacture of books. Here, the entire life-cycle CO₂ (LCCO₂) emissions for books, including book distribution, are calculated in terms of realistic scenarios. The life cycle is divided into three segments-upstream, midstream, and downstream-and each is examined carefully. We find that a large part (three-quarters, in fact) of the environmental load originates in the upstream segment, which mainly involves paper procurement mainly. The negative environmental impacts are quite significant across production, delivery, and recycling when considering a business model wherein 40% of the books are expected to remain unsold. Drastic reductions in the CO₂ emissions can be realized by replacing a certain portion of the paper-based market with electronic books. Although such a drastic change in the existing business model may impose a significant economic burden on incumbent publishers, the advantages for the consumers are that books can be made available at lower prices and new publishers will find it easy to enter the market because of the lower operating costs. A rapid shift to electronic book is important from the standpoint of both the consumer and service provider. The shift to electronic books is necessary to meet the global warming reduction targets set for 2020. And continuous efforts are necessary to reduce CO₂ emissions by not less than 25%.