Enjoy oxygen?  Pay attention.

Animal and plant species are becoming extinct at an alarming rate. Because the earth has had five prior periods of rapid and catastrophic extinctions (dinosaurs being the most famous) the term "sixth extinction" has been coined. The one major difference between the sixth extinction and the five previous ones is this one is primarily caused by humans.

ABC-CLIO's Encyclopedia of Biodiversity covers one of the most pressing scientific and social issues facing the planet at the moment – the loss of biodiversity. A monumental reference on the subjects of both ecology and evolution, it's structured around the "four questions" examined in the American Museum of Natural History's "Hall of Biodiversity":

•  What is Biodiversity? – the answer describes the major groups of organisms and types of ecosystems on the planet. It examines biodiversity's fields of study, evolutionary biodiversity, the processes of ecology and geology, and more.

•  Why should we care about biodiversity? – this discussion explains the "uses" of biodiversity, looking at the importance of the world's ecosystems and species to human medicine and agriculture. It addresses vital ecosystem "services," such as production of oxygen, clean air and water.

•  What are humans doing to destroy biodiversity? – this section covers human ecology, direct causes of extinction (habitat destruction) and endangered species (bald eagle, dodo, and quagga).

•  What can we do to preserve biodiversity? – readers explore the relationship between humanity and the natural world, focusing on important topics such as human population growth and the distribution and consumption of natural resources.

In addition to articulate essays discussing biodiversity's critical issues in detail, this up-to-date encyclopedia features an illustrated A-to-Z section boasting 400 entries written by leading scholars in the field. 

Having curated the American Museum of Natural History's "Hall of Diversity" exhibit, the volume's editor Niles Eldredge is keenly aware of how answering its four questions extends and complements education on the basic elements of evolution and ecology and the nature of the world's living species and ecosystems. 

A must-have title for science classes (biology, anthropology, geology) and numerous cross-disciplinary courses in environmental studies and the human social and political condition, the Encyclopedia of Biodiversity also provides an engaging preface, introduction, and detailed general index.

Niles Eldredge is curator of the Department of Invertebrates at the American Museum of Natural History. Most famous for co-authoring (with Stephen Jay Gould) the theory of "punctuated equilibrium" as a method of evolution, Eldredge has written numerous scholarly and popular works on evolution, ecology and biodiversity.