Opinion: Human impact creates ‘Anthropocene’

Our earth has suffered five great extinctions. The first occurred 443 million years ago when the climate cooled; the second, a million years later when the climate began warming. Both extinctions only affected ocean life as no land creatures yet existed. The Permian-Triassic Extinction occurred 251 million years ago, wiping out 96 percent of marine species and 70 percent of terrestrial species. The Triassic-Jurassic Extinction took place when 76 percent of marine and terrestrial species died off and dinosaurs outnumbered mammals. The fifth, and best known of the events was the Cretaceous-Paleogene Extinction, which may have been caused by a meteor crashing into the planet, causing the eradication of most life on earth, including most dinosaurs, about 65 million years ago.

Geologic time

Geologists do not measure time with a Rolex. Observable changes to the planet take place over millions of years, and — most recently — decades.

According to Seth Borenstein, writing for the Associated Press, “Geologists measure time in eons, eras, periods, epochs, and ages.” Further, he wrote that we have transitioned from the Holocene Epoch, which started about 11,700 years ago to a new epoch. A subcommittee of the International Commission of Stratigraphy has dubbed it “The Anthropocene.”