Q. Why publish this book now?

A. Because a lifetime of research has magnified my perception that we are in a crisis with reference to the living part of the environment.We now have enough measurements of extinction rates and the likely rate in the future to know that it is approaching a thousand times the baseline of what existed before humanity came along.

http://www.nytimes.com/2016/03/01/science/e-o-wilson-half-earth-biodiversity.html