Books such as America's Climate Choices, and more than 4,000 others, are now available for free online, as the National Academies Press has made all PDF versions of its books downloadable to anyone at no charge.

The National Academies Press, which is the publisher for the National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council, has been offering free content online since 1994. Before last week all of its PDFs for books and reports were free to download in developing countries, and 65 percent of its PDFs were available for free overall.

Now, with a few exceptions, all PDF books in its catalog and future titles will be that way. (Printed books will still be sold.)

Our business model has evolved so that it is now financially viable to put this content out to the entire world for free, said Barbara Kline Pope, the National Academies Press' executive director, in a statement. This is a wonderful opportunity to make a positive impact by more effectively sharing our knowledge and analyses.

The NAP said it expects the change to increase its PDF downloads from about 700,000 per year to more than 3 million by 2013. The press publishes more than 200 books each year.

To check out its books, see

Edward B. Colby is the Books section editor of the International Business Times. He can be reached at