The Millennium Ecosystem Assessment

Its findings provide a state-of-the-art scientific appraisal of the condition and trends in the world’s ecosystems and the services they provide: 

The Millennium Ecosystem Assessment found that:

Over the past 50 years, humans have changed ecosystems largely to meet rapidly growing demands for food, fresh water, timber, fibre and fuel. This has resulted in a substantial and largely irreversible loss in the diversity of life on Earth.

Gains have been achieved, but at  growing costs to the ecosystem services. Unless the issues are addressed, future generations will benefit less. It is possible to reverse the degradation of many ecosystem services over the next 50 years, but the changes in policy and practice required are substantial and not currently underway.

Extinction is a natural event and, from a geological perspective, routine. We now know that most species that have ever lived have become extinct. The average duration of a species is 2-10 million years (based on the last 200 million years).