Extinction also is a lineage termination, which removes a potential ancestor from which other species could evolve. Extinction is a double whammy. Diversification takes a long time to ramp up. Such complexity may also be the reason that the size of the extinction is relatively unimportant in determining the time it takes the ecosystem to recover. Extinction totally alters the ecosystem, making recovery a slow process no matter what the scale.
Life reaches a new but different plateau.
Kirchner notes that their sobering findings don't necessarily imply a stark fate for the Earth. Our future depends on what we choose to do on a national and international level, as a society. Those decisions are critical because they will have very long-lasting consequences. If we deplete Earth's biological diversity, we will leave a biologically impoverished planet, not only for our children and our children's children, but for all the children of our species that there will ever be. The work was supported by grants from the University of California and the National Science Foundation.