The symbol is composed of an hourly glass (the two triangles) surrounded by a circle (representing the Earth.)
Will Homo Sapiens and world-wide capitalism destroy our planet?
Daniel Smith has written an excellent book review in the May 2014 edition of Harper's Magazine. The name of the book is The Sixth Extinction: An Unnatural History by Elizabeth Holt, 352 pages. Henry Holt and Company.
I have already ordered my copy.