The Earth is in the midst of a sixth mass extinction, and it’s picking up speed. The researchers analyzed numbers and distribution of critically endangered species. They determined that 515 species of terrestrial vertebrates have fewer than 1,000 individuals left, meaning they’re very close to extinction. Nearly half of those species have fewer than 250 surviving members, mostly due to human encroachment. The first five mass extinctions in the last 450 million years each destroyed 70% to 95% of animal, plant and microorganism species. Huge changes to the environment, such as asteroids, volcanic eruptions or depletion of oceanic oxygen caused the first five. The sixth, the study finds, is our doing.
— source Stanford News Service, pnas.org
| 2020/05/27