The Sixth Mass Extinction, the Environmental Crisis and the Future of Humanity

In the history of life on Earth, there have been five mass extinctions – episodes where large numbers of species became extinct in a short time. All previous mass extinctions stemmed from natural catastrophes, such as volcanic eruptions, depletion of oxygen in the oceans, and meteorite impact. The ongoing sixth mass extinction is different, as it is caused by human activity. According to a natural, physiological extinction rate, one would expect to lose two species for every 10,000 species present every 100 years. Current figures show that 477 species have become extinct in the last 100 years. Under a natural extinction rate, we would have expected to have only nine extinctions; in other words, there were 468 more extinctions than would be expected in the last century! This evidence is dramatic and tragic. At this pace, we may lose a large proportion of vertebrates, including mammals, birds, reptiles, amphibians, and fishes, in the next two to three decades. Losing them has many consequences. Those species are essential to maintain ecosystem services, which are all the benefits that we get for free from the proper function of nature. The combination of the atmosphere's gases, the quality, and quantity of water, soil fertilization, pollination are ecosystem services. By losing species, we are eroding the conditions of Earth that are essential for human well-being. Habitat loss due to agriculture, forestry, mining, urbanization, overfishing and overhunting, pollution, greenhouse gas emissions, and human overpopulation are the leading causes of the ongoing mass extinction. We still have time to avoid the most tragic consequences of the sixth mass extinction: saving endangered animals is the only way humanity has to save itself.