In an essay that Edward O. Wilson wrote in 2018 for the Encyclopædia Britannica Anniversary Edition: 250 Years of Excellence, he identified mass extinction as the greatest threat to Earth’s future: “We share the planet with a roughly estimated 10 million other species. They are being extinguished at a rate between 100 and 1,000 times faster than before the arrival of our own species. The effect could be the reduction of Earth’s biodiversity to half its present amount by the end of the century.”