SIGNS OF THE ‘HUMAN AGE’

Apr 18, 2016 by

 

By NICHOLAS ST. FLEUR  NYTDOT

 

Welcome to the “Anthropocene” — a new epoch in our planet’s 4.5 billion year history. Thanks to the colossal changes humans have made since the mid-20th century, Earth has now entered a distinct age from the Holocene epoch, which started 11,700 years ago as the ice age thawed. That’s according to an argument made by a team of scientists from the Anthropocene Working Group. Scientists say an epoch ends following an event – like the asteroid that demolished the dinosaurs and ended the late Cretaceous Epoch 66 million years ago – that altered the underlying rock and sedimentary layers so significantly that its remnants can be observed across the globe. In a paper published Thursday in Science, the researchers presented evidence for why they think mankind’s marks over the past 65 years ushered in a new geological time period. Here are a few examples:
or the Anthropocene

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Soybeans harvested at a farm in Tangara da Serra, in western Brazil. Credit Paulo Whitaker/Reuters
Modern Agriculture

In the last century, fertilizers used in crop production doubled the amount of nitrogen and phosphorus in the soil. Signals of these chemicals found within lake strata are now at their highest levels in the past 100,000 years.
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Aluminum parts for a 2015 Ford F-150 truck going through the assembly line at the Ford Dearborn Truck Plant. Credit Bill Pugliano/Getty Images
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Rarely found in its native form before the 1800s, global production of aluminum has increased by 98 percent since the 1950s.
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A large concrete structure on the beach in Highlands, N.J. Credit Mel Evans/Associated Press
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Pervasive since World War II, concrete is now the world’s primary building material. The amount produced in the last 20 years is enough to cover each square foot of the planet with three ounces of concrete.
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Crushed bottles at a recycling center. Credit Paul J. Bereswill for the New York Times
Plastic

The amount of plastic produced each year weighs roughly as much as all humans on Earth combined. Some is recycled, but most gets discarded to landfills or ends up in the ocean. Plastics, along with aluminum and concrete, decay very slowly and will leave behind identifiable fossils, called “technofossils,” in the geological record.
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A file picture from 1971 shows a French nuclear test in the south Pacific atoll of Mururoa. Credit Agence France-Presse — Getty Images
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Fallout from thermonuclear weapons detonated in the mid-20th century generated clear signals of carbon-14 and plutonium-239 across the globe that will be detectable in sediments and ice for at least 100,000 years.

A garbage dump site in Nonthaburi province on the outskirts of Bangkok. Credit Rungroj Yongrit/European Pressphoto Agency
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Materials disposed in landfills and used in construction and mining have introduced the greatest number of
Overpasses in Chengdu city, one of the fastest-urbanizing cities in China. Credit Justin Jin for The New York Times
Urban Structures

Humans have transformed more than half of Earth’s land surface with buildings, roads, mines, farms and landfills, among other uses.
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The Friant Dam forms Millerton Lake in California. Credit Max Whittaker for The New York Times
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In the past 60 years, large dams have been constructed worldwide at a rate of one per day. Each will last for 50 to 200 years, interrupting the flow of sediments to the ocean and disrupting the formation of rock layers.

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