The Sixth Extinction Crisis Loss of Animal Populations and Species

Today the number of species is the largest in the history of life; however a considerable proportion of that biodiversity is endangered and many species have suffered anthropogenic extinctions. Species and population extinctions are natural phenomena, and massive biodiversity declines have occurred five times in the remote geological past. However, the current extinction episode, the “sixth extinction wave,” may prove to be the most rapid and devastating. To assess the seriousness of this wave, we analyze the present extent of life’s diversity, the number of species that have gone extinct in historic times, the current rates of species extinction, and the extent of population losses. Estimates of the likely number of eukaryotic species vary from 5 to 100 million, but we are now in a “new age of discovery.” There is an explosion of descriptions of new species even in previously “well-known” groups such as mammals, suggesting that previous estimates of the magnitude of biodiversity may be too low. Based on the 2008 IUCN evaluation of the status of world´s species, we estimate that extinctions caused by human activities are occurring at a rate thousands of times higher than the background rate.

Keywords: biodiversity, extinction vertebrates, new species, population losses, sixth extinction crisis

Ceballos G., A. García, and P.R. Ehrlich. 2010. The Sixth Extinction Crisis Loss of Animal Populations and Species. Journal of Cosmology 8:1821-1831.