Mass Extinction Underway | Biodiversity Crisis | Global Species Loss: "Most of his peers apparently agree. Nearly seven out of 10 of the biologists polled said they believed a 'mass extinction' was underway, and an equal number predicted that up to one-fifth of all living species could disappear within 30 years. Nearly all attributed the losses to human activity, especially the destruction of plant and animal habitats.
Among the dissenters, some argue that there is not yet enough data to support the view that a mass extinction is occurring. Many of the estimates of species loss are extrapolations based on the global destruction of rain forests and other rich habitats."