Humans have only been on Earth for a minute fraction of the time the planet has existed. Yet everywhere you look, we have left a trace of our presence.
We’ve reshaped the landscape by clearing forests and building new islands, altered the makeup of the atmosphere by driving cars and running factories, and even modified the types of rocks that will be found millions of years from now.
According to a recent study, our impact has been so extreme that it makes the appearance of oxygen — an event that geologists call the Great Oxidation — look trivial.
Scientists call our geologic epoch the Anthropocene — it began around the time we detonated the first atomic bomb and coated the planet with radioactive particles.
“If the Great Oxidation … was a ‘punctuation event’ in Earth’s history, the rapid and extensive geological impact of the Anthropocene is an exclamation mark,” Robert Hazen, a mineralogist and astrobiologist at the Carnegie Institution for Science’s Geophysical Laboratory, told Business Insider.
While there is plenty of evidence of humans’ impact on the planet that we can easily observe — the construction of cities, a changing global climate, the extinction of other species — one of the most dramatic effects is invisible to most people.
Disturbing the Earth’s surface
Hazen helped write a recent paper that catalogued for the first time the hundreds of new minerals that humans have left behind. The scientists’ work suggested that humans are responsible for roughly 4% of all the minerals on Earth — the most new materials to show up in the geologic record since oxygen appeared more than 2.2 billion years ago.
These materials will be visible for millions or even billions of years and will “mark our age as different from all that came before,” said Edward Grew, a professor of earth and climate sciences at the University of Maine and one of Hazen’s co-authors.
Human activities are responsible for at least 208 brand-new minerals. Many of those have formed along the walls of mines, where cool, moist air reacts with sooty particles of iron ore.
“When one looks at a mine, it’s really a disturbance of the Earth’s surface,” Grew said.
In a mine, dozens of activities can give rise to new minerals — including the dumping of large amounts of iron or copper ore, the build-up of water along mine tunnel walls, and even fires inside mines.
Some of the new minerals that have resulted from human activity are eye-catchingly beautiful. On a copper mining tool at the Rowley Mine in Maricopa County, Arizona, Hazen and his colleagues found a glowing, sea-coloured mineral called simonkolleite.
“You’re just stirring a pot in a way, exposing ores to a different environment and getting these new minerals to form,” Grew said.
In addition to creating new minerals, humans are also moving around existing ones and shifting how they are distributed globally.
Minerals like abhurite, which are essentially the result of corrosion that happens after a shipwreck or another human-made disaster, can be found across the planet. Hazen and his colleagues found a piece of abhurite from the wreckage of the SS Cheerful, which sunk in 1885 near Cornwall, England.
“What we’re seeing…these are things that will persist in the geologic record that a million years from now people will find,” said Hazen. “It’s this incredibly rapid pulse caused by human activity.”
Hazen’s log, while extensive, still doesn’t cover all of the mineral-like materials that humans have created. These additional materials include magnets, alloys, and building materials like bricks and concrete. Hazen estimates that there are hundreds or even thousands more of these materials that researchers have yet to officially classify.
“We’re talking about a pervasive layer of Earth’s surface which humans have changed in fundamental ways,” said Hazen.