Loss of Biodiversity

Of the three "tipping points" the authors of «Planetary Boundaries» believe the human race has already passed, the loss of biodiversity is the most dramatic. The Earth is currently in the midst of the greatest mass extinction since the death of the dinosaurs 65 million years ago. As many as half of all plant and animal species that exist today could be extinct by 2100, a rate that is an estimated 1000 times the natural rate of 0.1-1.0 species per million species per year.

This catastrophic loss of biodiversity is already likely to affect the development of life on earth for millions of years to come. Following the largest mass extinction in Earth's history – the Permian-Triassic extinction event that occurred about 251 million years ago – it took 50 million years for land-dwelling species to regain their previous diversity, and more than 100 million years for ocean biodiversity to recover.

The cause or causes of the Permian-Triassic extinction are still unknown, but the cause of the current mass extinction sadly is not. The majority of modern extinctions are directly or indirectly caused by human activity. Habitat destruction, overhunting/overharvesting, competition from invasive alien species, and climate change are a few of the most common causes of extinction.

In addition to an almost unimaginably impoverished world, mass extinction also threatens to lead to the collapse, domino-style, of entire ecosystems, ecosystems that the human race depends on for its own survival. So-called "ecosystem services" are believed to save human societies trillions of dollars every year by performing functions such as the following:

• purification of air and water
• crop pollination
• production of seafood, game, and other wild foods
• pest control
• waste decomposition
• soil creation
• drought and flood mitigation
• and more

Healthy ecosystems perform ecosystem services more effectively than stressed or destroyed ecosystems.