The following references are from the Green Press Initiative:
- An average book of 250 pages, selling 1 million copies requires 12,000 trees!
- On average, the US book industry uses less than 10% recycled fiber for its paper.
- Deforestation accounts for 25% of human caused CO2 emissions.
- Over the course of its lifecycle, post consumer recycled fiber requires 30-40% less energy than virgin fiber.
- Paper accounts for nearly 40% of the waste stream.
- In 2006, an Opinion Research Corporation poll revealed that 80% of readers are willing to pay more for books printed on recycled and environmentally responsible paper.
- Globally, over 40% of the industrial wood harvest is used to make paper.
- When the goals set forth in the Book Industry Treatise on responsible paper use are realized, over 5 million trees will be preserved each year.
And here is the most wonderful understanding of the roles of trees via an excerpt from Gaia's Garden by Toby Hemenway, http://www.chelseagreen.com/blogs/the-many-roles-of-a-tree/
As far as digital readers being more sustainable...not yet, for many reasons. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3908467/