Biological Extinction and Climate Change

Abstract

What are the current dimensions of biological diversity? Taxonomists have described approximately two million species of eukaryotic organisms. Many more remain unknown, and the global total may approximate 12 million species or more. Generally, for the past 65 million years, the rate of extinction of these species appears to have been ~0.1 extinctions per million species per year. Now, however, as a result of human activities, it has increased by about 1000 times, to ~100 species per million per year. We are losing species at about 1000 times the rate at which new ones are evolving. Many species are local and particularly liable to extinction, with climate change and increasing human-related pressures of all kinds pushing very strongly on life as it exists. Most of the species cannot be saved by forming parks and protected areas or away from their natural habitats unless human pressures are lessened by general action among nations, a prospect that is not being well realized at present. The strong call for the preservation of biodiversity in the encyclical Laudato Si’ represents the kind of ethical responsibility that must be adopted if there is to be any hope for the survival of our civilization.