Species Extinctions

An article discusses the impact that humans are having on other species. As one might guess, it isn't positive. The Center for Biological Diversity writes:

We're in the midst of the Earth’s sixth mass extinction crisis. Harvard biologist E. O. Wilson estimates that 30,000 species per year (or three species per hour) are being driven to extinction. Compare this to the natural background rate of one extinction per million species per year, and you can see why scientists refer to it as a crisis unparalleled in human history.

The current mass extinction differs from all others in being driven by a single species rather than a planetary or galactic physical process. When the human race — Homo sapiens sapiens — migrated out of Africa to the Middle East 90,000 years ago, to Europe and Australia 40,000 years ago, to North America 12,500 years ago, and to the Caribbean 8,000 years ago, waves of extinction soon followed. The colonization-followed-by-extinction pattern can be seen as recently as 2,000 years ago, when humans colonized Madagascar and quickly drove elephant birds, hippos, and large lemurs extinct.

The first wave of extinctions targeted large vertebrates hunted by hunter-gatherers. The second, larger wave began 10,000 years ago as the discovery of agriculture caused a population boom and a need to plow wildlife habitats, divert streams, and maintain large herds of domestic cattle. The third and largest wave began in 1800 with the harnessing of fossil fuels. With enormous, cheap energy at its disposal, the human population grew rapidly from 1 billion in 1800 to 2 billion in 1930, 4 billion in 1975, and over 7.5 billion today. If the current course is not altered, we’ll reach 8 billion by 2020 and 9 to 15 billion (likely the former) by 2050.

Humans’ impact has been so profound that scientists have proposed that the Holocene era be declared over and the current epoch (beginning in about 1900) be called the Anthropocene: the age when the "global environmental effects of increased human population and economic development" dominate planetary physical, chemical, and biological conditions.

• Humans annually absorb 42 percent of the Earth’s terrestrial net primary productivity, 30 percent of its marine net primary productivity, and 50 percent of its fresh water.
• Forty percent of the planet’s land is devoted to human food production, up from 7 percent in 1700.
• Fifty percent of the planet’s land mass has been transformed for human use.

Large animal extinctions are not mostly due to hunting any more. Instead, those extinctions mostly arise from loss of habitat and human-caused climate change. Assuming there is a will to act, those are things we can actually do something about.