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Human impact on the planet qualifies as a new geological epoch, say scientists

We've made our mark.

PETER DOCKRILL
8 JAN 2016
 

There's no denying humans have made a considerable impression on our natural environment – not all of it positive, unfortunately – and now an international team of geoscientists says that the impact we've had on the planet qualifies as a distinct geological epoch.

The group argues that the 'Anthropocene', which commenced about halfway through the 20th century, is functionally and stratigraphically distinct from the 'Holocene' epoch that immediately preceded it for almost 12,000 years.

 

According to the researchers, the Anthropocene is marked by a worldwide spread of new materials and gas emissions that have left sufficient measurable signals in the ground so as to justify recognition of a new epoch within the geological time scale.

"Humans have long affected the environment, but recently there has been a rapid global spread of novel materials including aluminium, concrete and plastics, which are leaving their mark in sediments," said Colin Waters of the British Geological Survey. "Fossil-fuel combustion has dispersed fly ash particles worldwide, pretty well coincident with the peak distribution of the 'bomb spike' of radionuclides generated by atmospheric testing of nuclear weapons."

Taken together, the researchers say the impact of these kinds of materials and emissions has produced a range of signals in sediments and ice that weren't in existence during the Holocene.

The Anthropocene, which has been discussed as a varying concept for decades, would not have resulted without the rapid environmental changes stemming from surges in human population and increased levels of consumption that presented in the 20th century, according to the researchers. "We are becoming a geological agent in ourselves," Waters told Alister Doyle at Reuters.

Prior proposals for when the Anthropocene commenced have included the spread of agriculture and deforestation several thousand years ago, the Columbian Exchange of species after 1492, and the Industrial Revolution (1760–1840), but the authors of the current study propose that the proliferation of uniquely human materials such as plastic and concrete in the last 70 or so years provides a more useful definition.

"Not only would this represent the first instance of a new epoch having been witnessed firsthand by advanced human societies, it would be one stemming from the consequences of their own doing," the authors write in their paper, which is published in Science.

The findings will likely be considered by the International Commission on Stratigraphy, the body that formally approves such epoch divisions, when it meets later in 2016.

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