Readers may have missed this engaging opinion piece in Sunday's New York Times: How Green Is My Ipad?
Granted, a true environmental audit of the life-cycle of either a printed book, or an Ipad, is presently an inexact science. The authors present a plausible analysis, but it contains several asssumptions or unknowns, and given its length can't begin to get into the technicalities of print book production: illustrations? acid-free paper? binding type? size of the volume? etc. --details which do matter in this context.
Still, very rough figuring in the world of libraries:
One e-book reader has the approximate impact of 100 printed book circulations (each circulation counting as one use, which is a debatable assumption). Given the impact of individuals going to a library to get a book (on foot on campus, or using an automobile? or public transportation in a city? or a bicycle?), one might err generously and say that the approximate impact upon global climate change and human health would add up:
one e-book reader = 150 paper book circulations
but even that might be too generous. Then must be figured in the cost of storage, retrieval, processing, and repair of printed books, which is a practically incalculable per-piece figure in an academic library with perhaps many hundred thousand volumes --some of which will remain in the collection for centuries or decades, while others are ephemeral.
A very general conclusion: the positive environmental impact of e-book readers is often overerestimated, and the positive impact of many printed volumes is usually under-estimated. In fact, paper is not a bad storage medium, in bulk. It is expensive and time-consuming to handle. On the other hand, the impacts on human health and global climate change of e-book readers and changing electronic formats cannot be over-looked in a pundits' rush to proclaim the death of the library.