Humans have had an enormous impact on the Earth. Some scientists think our actions merit the start of an entirely new epoch on the geological time scale, and it's called the Anthropocene.
A group of specialists called the Anthropocene Working Group are trying to get the new epoch formally recognized. They argue that since the 1950s, humans have left a measurable mark on the planet by disrupting the carbon cycle, contributing to climate change and sea level rise, aiding in species invasion and leaving behind a geological record of materials like plastic.
"Many of these changes are geologically long-lasting, and some are effectively irreversible," according to a release from the University of Leicester.
The Anthropocene would mark the end of the Holocene epoch, which began after the last major ice age.
Where does the Anthropocene start?
Right now the AWG is working on finding evidence in the geological record that will act as the starting point of the Anthropocene, AWG geologist Jan Zalasiewicz explained in an email.
They'll have to meticulously look through things like ice cores, ocean sediments and coral samples. For example, some geologists think that traces of plutonium left over from bomb testing will be found in ocean sediments or ice layers, according to the BBC. Others think preserved particles of plastic that never break down will be a good starting point. Still others think a sharp spike in carbon dioxide would serve as a good starting point.
Whatever the starting point is, the AWG scientists all agree they should be searching for a point around the 1950s when human impact on the Earth started rapidly accelerating.
The team has a lot of work ahead of them now, Zalasiewicz said. If they find a good starting point for the Anthropocene with lots of geological evidence backing it up, they'll submit a proposal to international geology committees where the members will decide whether or not to make the Anthropocene an official epoch.
"The Geological Time Scale is pretty well the backbone of geology, and is meant to be as stable as possible," Zalasiewicz explained. "The stratigraphic bodies that govern it are reluctant to change it, and will only do so with a very carefully, scrupulously prepared case with lots of 'classical' stratal evidence (the work that we are about to do) — and even then not always."
The idea of the Anthropocene is very new, so it'll take a lot of convincing to get it recognized, Zalasiewicz said.
"Our spadework will have to be very good," he said.