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Surprising Science

Humans Are Making an Alien Earth

Will homo sapiens define a geological period in the way dinosaurs—and their vanishing act—helped mark the Jurassic and the Cretaceous? Yes, say scientists, for better or worse. 

What’s the Latest Development?

When scientists gathered recently at the British Geological Society in London, many argued that humans are leaving an indelible mark in the Earth. Should aliens come to visit the planet in 10 million years, they would be able to discern our human period from future evidence in the fossil record. This period of human influence on the Earth is called the Anthropocene. Since the mid-19th century, when man’s engineering influence began to rage, humans have been altering Earth’s chemical composition: “The burning of fossil fuels has altered the composition of the atmosphere, pushing the concentration of carbon dioxide to levels unseen at least for 800,000 years, perhaps for three million.”

What’s the Big Idea?

The question becomes how long the Anthropocene will last and whether our species will prove resilient and resourceful enough to weather the changes to the Earth we are currently causing. “We are sculpting the surface of the Earth,” said James Syvitski, a professor at the University of Colorado, who points to two centuries of industrial-scale mining, damming, deforestation and agriculture. “To validate the Anthropocene, all these changes will be measured against the range of variation in our current geological period—the Holocene epoch—which began some 12,000 years ago as Earth emerged from the last ice age.”


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