From 100,000 to 10,000 years ago, Foer explains, the average global temperature was seven degrees Celsius lower than it is today. 50 million years ago, the Arctic was a lush tropical paradise (75). Foer concludes after bulleting these two facts, “As with body temperatures, a few degrees can be the difference between health and crisis” (75).

There have been five mass extinctions. 250 million years ago, volcanic eruptions warmed the oceans, killing 96% of marine life and 70% of life on land. The Anthropocene period—which begins at the geological age and ends at the Industrial Revolution—is characterized by human activity. The Anthropocene represents the 6th mass extinction (76). It is the first time climate change is the cause of the mass extinction, as well as the first time a mass extinction has been caused my humans, not a natural event.

Humans represent 0.01% of life on Earth. Since the advent of agriculture, we have destroyed 83% of all wild animals and half of all wild plants (78).