It is the diversity of life forms and their interactions with each other and with the rest of the environment that has made the earth a habitable place for humans. Biodiversity provides a range of materials and services that sustain us - from the production of oxygen and nutrients to the purification of wastes.
While human civilization is increasingly dependent on these services, our way of life is also causing the erosion of biodiversity. Our economy and lifestyle based on the unsustainable consumption of resources from plants and animals, which also involves the release of wastes and toxic materials into the environment, contributes to species loss. Species are disappearing at 50 to 100 times the natural rate of extinction and this is expected to rise dramatically during this century. Based on current trends, an estimated 34,000 plant and 5,200 animal species - including one in eight of the world's bird species - currently face extinction.
Agricultural systems have also relied on a broad range of plant and animal species and varieties. This diversity is also shrinking, as modern agriculture focuses on relatively few, highly productive crop varieties and livestock breeds.
While we are often most aware of threats to individual species, such as Whooping Cranes or Burrowing Owls, even more significant is the loss of ecosystem diversity. Vast areas of forests, wetlands, prairies and other ecosystems have been destroyed, degraded, fragmented, or converted to less diverse agricultural systems, forest plantations, or urban areas. Losses of these systems are the biggest threat to species biodiversity. Human-induced global changes like ozone depletion and climate change (link to Climate change issues page) add to this threat.
Each species and ecosystem has intrinsic value. Together, they provide "goods and services" that support life, including human life. Some of these invaluable services include: