In 1946, American consumer goods manufacturer Procter & Gamble rolled out a new product that, little known to its inventors at the time, would one day be proposed as a key geological component delineating mankind’s overwhelming influence on Earth’s ecosystem: Tide.
Tide, pitched to American consumers as the world’s first heavy-duty detergent, was a synthetic agent designed specifically for machine cleaning and by 1949 was being sold throughout the United States. Tide was hardly alone; it was just one of a vast number of synthetic compounds pouring out from plants and factories around the world after the second world war.
Now, a team of scientists based in Switzerland has proposed that this enormous flood of pollutants that emerged in the middle of the 20th century — including industrial chemicals, pesticides, pharmaceuticals, and personal care products like shampoos and lotions — was so vast, it should be considered a fundamental marker for the time period of humanity’s profound impact on Earth’s natural systems.
The proposal sets down a new point of reference in the debate over whether the Earth has entered a new geological epoch — known among scientists as the Anthropocene, or “the age of humans.”
“We humans have made a lot of changes to the Earth,” Aurea C. Chiaia-Hernández, an author of a paper published in the American Chemical Society journal Environmental Science & Technology, told Seeker. “We are now influencing so much that there’s a big debate about whether a new epoch, the Anthropocene, has begun.”
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Geologists agree that an epoch known as the Holocene began about 11,700 years ago, when the planet emerged from the last ice age. Yet some argue that the rise of humanity has brought such profound disruption to Earth’s ecosystems that the Holocene should now be declared finished.
If so, when should the Anthropocene be said to have begun: with the first explosion of an atomic weapon in the mid-20th century, the onset of the Industrial Revolution in 18th century and the rise in atmospheric concentrations of carbon dioxide that it kicked off, or even earlier with the biological exchanges between the New and Old Worlds in the 15th and 16th centuries?
The new study suggests one of the hallmarks of the Anthropocene could be the vast, post-WW2 outpouring of man-made, organic contaminants.
The researchers looked at sediment layers at the bottom of two Swiss lakes and found a dramatic uptick in the amount of human-produced, organic (meaning, materials that contain carbon) pollutants during the 1950s — so much so that the authors suggest that, judging from those samples, the Anthropocene could be said to have begun in exactly the year 1950.
While the Industrial Revolution has been proposed as the event that kicked off the Anthropocene, it has the disadvantage of being localized to western, developed nations, said Chiaia-Hernández, a chemist at the Swiss Federal Institute of Aquatic Science and Technology.
The rise of organic manmade contaminants after World War II, by contrast, was a more global phenomenon.
Chiaia-Hernández and her team used a technique known as high-resolution mass spectrometry, which measures the masses within a sample to determine its exact chemical makeup.
“Of course we can look for known compounds, but using this new technology, we can scan for anything [man-made],” she said. “We can see thousands of compounds just by looking by masses.”
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The researchers examined one-meter-long cores from each lake bottom, capturing the past 100 years of sediment layers.
According to their analysis, the lake sediments contained few synthetic contaminants prior to 1950. But during the 1950s, concentrations of industrial chemicals began to appear, thanks to the boom in industrial activity post-World War II.
The researchers say this record clearly demonstrates the beginning of large-scale human impact on the environment.
As the new epoch evolves, new pollutants are finding their way into surface waters to be discovered.
“The increase of chemicals entering into the market is so big, sometimes we can’t even keep up,” Chiaia-Hernández said.
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