The first Earth Day, held April 22, 1970, was designed to draw popular attention to environmental causes and the need to protect nature. It succeeded. At age 46, Earth Day continues to focus our minds on preserving the natural world, if only for a brief moment each year.
But what if a basic assumption about our planet, one that we all make on Earth Day and every other day, is wrong? What if, in 2016, we no longer inhabit the Earth we once did? What if the nature we seek to protect has already been profoundly altered - by us? Would that undercut the logic of Earth Day?
Many scientists and scholars wonder if the Earth has entered a new epoch in its 5 billion-year history. They are debating whether we should officially declare the end of the Holocene, the geological epoch that began 11,700 years ago, and the start of what they are calling the Anthropocene. The Holocene was great for our species. The climate was remarkably stable, helping us prosper as never before in humankind's 200,000-year history. The Anthropocene concept, as the root of the term suggests, rests on the notion that human activity has created a new version of an old planet.