Few scientists question that biodiversity is disappearing across the earth faster than it can be replaced. Although it is difficult to put a number on species loss when not all species have been identified, projections, trusted by the scientific community, show that up to 50 percent of Earth's animals and plants could be on the path to extinction. (Morell, 1999)

Earth's five past extinctions. Graph from Conserving Earth's Biodiversity.

Nearly all biologists believe we are currently in a state of mass extinction - a period of extreme species loss which puts life on Earth in jeopardy. Although extinction is a normal biological process, it does not usually occur so quickly for so many species.

Although there have been five mass extinctions since the beginning of the Earth, none of them have occurred as rapidly as the species loss scientists estimate today. Also, unlike the other mass extinctions that were caused by natural phenomenon, most biologists believe this extinction was initiated by a single species - humans. (Conserving Earth's Biodiversity, 2000)

For this reason, biologists today consider the loss of biodiversity the chief environmental concern, above ozone layer depletion, global warming, pollution and contamination. (American Museum of Natural History, 1998)

Read about the one dissenting statistician.