Geologists are looking for a site that best demonstrates how humans have changed the structure of our planet’s surface. This place will best illustrate when a new epoch called the Anthropocene was born and its predecessor called the Holocene came to an end.
The Holocene began at the end of the last ice age 11,700 years ago as the great glaciers that had previously covered the Earth began to retreat. This allowed modern humans to spread across the planet.
Homo sapiens flourished during the Holocene but our expansion had geological consequences. The minerals we mined, the gases we released by burning fossil fuels and the radioactive material we have produced have made significant changes to Earth’s geology.
A key indicator of the impacts that humans have had on our planet’s geology is the presence of aluminum, said geologist Jan Zalasiewicz. “In nature, pure metallic aluminium is rarer than hen’s teeth. It exists only in tiny amounts. Virtually all our aluminium comes from ores in which the metal has formed compounds with other elements.
“Over the past 100 years, we have mined these oxides, hydroxides and silicates, processed them, and extracted around half a billion tonnes of metallic aluminium from them and used it to make everything from pots to airplanes.”
Another example is the presence of the element plutonium. It is extremely rare. Nuclear bombs, tested in the atmosphere, released plutonium which settled on the ground in easily detectable amounts.
Another clear example is provided by the species we have helped spread around the globe, including the Pacific oyster and the zebra mussel.
And of course, a very good indicator is the presence of plastics.
“In the distant future, tens of millions of years from now, advanced species will still be able to detect how we changed the Earth. We need to realize that now,” said Zalasiewicz.