New assessment suggests Anthropocene started in the 1950s

A team of Earth scientists from the Center for Marine Environmental Studies, the University of Tokyo, The Australian National University, Matsuyama University, Kyoto University, and Shimane University, has found, via a new assessment, that the 1950s is the strongest candidate for the start of the Anthropocene.

In their paper published in Proceedings of the National Academy of Sciences, the group describes how they compared the three top contenders, and why they chose the 1950s, as the most likely marker.

In 2002, Nobel laureate Paul Crutzen suggested that the Holocene had ended and that a new era in planetary history had begun—the Anthropocene. The new era, he suggested, was one dominated by changes to the planet that had occurred because of human behaviors.

Since then, planetary scientists have debated the issue, with some suggesting that there is more than enough evidence to declare the start of a new era, and others claiming there is not yet enough. In this new study, the research team began with the belief that there is enough evidence to support the start of the Anthropocene, and because of that there must be a point at which it began.

In looking at available evidence, the researchers suggest that there are three good candidates; the first being the late 1800s. It was during this period, they note, that the Industrial Revolution began. They also point out that it was a time during which levels of lead began to be spread across major land surfaces, along with stable isotope ratios and changes in the balance of nutrients.

The second candidate they suggest was the early 1900s, which saw changes in pollen across the globe, major increases in black carbon and widespread changes in stable isotopes.

The third candidate, the middle of last century, saw the most measurable global and permanent changes. This was when organic pollutants began showing up all over the world, along with plastics and microplastics. It was also the start of the nuclear age, with evidence of test blasts found everywhere on Earth—and finally, it was the beginning of major impacts resulting from global warming.

After comparing the global impact of all three candidates, the research team concluded it was the third that most likely should be considered as the true start of the Anthropocene. They suggest it shows the most easily seen and measured global changes—changes that would likely take thousands, if not millions of years to change back to Holocene levels, should humans depart the scene.

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