Are We in a New Epoch? The Case for the Anthropocene

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The proliferation of concrete on Earth’s surface is one piece of evidence scientists suggest supports the designation of a new epoch called the Anthropocene. (Photo credit: UpperCut Images/Alamy)

The Holocene Epoch began around 12,000 years ago. Are we now in the Anthropocene? In a recent study published in Science magazine, some scientists argue that we indeed have entered a new epoch. The question will be put to the International Union of Geological Sciences (IUGS) later this year. The primary goal of the IUGS is to precisely define global units – including systems series, and stages – that are the basis for the units – periods, epochs, and ages – of the International Geologic Time Scale.

“Humans have long affected the environment, but recently there has been a rapid global spread of novel materials including aluminum, concrete, and plastics, which are leaving their mark in sediments,” Dr. Colin Waters, a principal geologist at the British Geological Survey and lead author, said in a press release about the study. “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.”

According to the study, coauthored by 24 members of the Anthropocene Working Group, humans have altered Earth in ways that can be seen in sediments and glacial ice cores, and these changes justify the official recognition of a new epoch in the geologic time scale.

Evidence that Supports the Anthropocene Epoch:

  • New Anthropogenic Materials – recent deposits contain new minerals and rock types including aluminum, concrete, and plastics. These human-made deposits are the products of mining, waste disposal, construction, and urbanization.
  • Modification of Sedimentary Processes – human activities have drastically altered over 50 percent of Earth’s land surface through activities such as mining, agriculture, drilling, and forest clearing.
  • Changed Geochemical Signatures in Recent Sediments and Ice – human activities have introduced into the sedimentary record increased concentrations of polyaromatic hydrocarbons, polychlorinated biphenyls, and pesticide residues. Increased fertilizer use in the past century has doubled the amount of nitrogen and phosphorus in soils. Runoff of these nutrients into lakes and other waterways has negatively impacted aquatic ecosystems.
  • Radiogenic Signatures and Radionuclides in Sediments and Ice – the fallout from nuclear testing from the mid 1940s through the early 1960s has left a global radiogenic signature, concentrated in the mid-latitudes and highest in the Northern Hemisphere, where most of the testing occurred. 239Pu, which first appeared in 1951, will be identifiable in sediments and ice for the next 100,000 years.
  • Carbon Cycle Evidence From Ice Cores – atmospheric CO2 and CH4 concentrations have exceeded Holocene levels since at least 1850.
  • Climate Change and Rates of Sea-level Change Since the End of the Last Ice Age – an average global temperature increase of 0.6°C to 0.9°C from 1900 to the present, is now rising beyond the Holocene variation of the past 14,000 years. Global sea levels increased at 3.2 ± 0.4 mm/year from 1993 to 2010 and are rising above Late Holocene rates.
  • Biotic Change as an Indicator of the Anthropocene – extinction rates have far exceeded background rates since 1500 and significantly increased beginning in 19th century and continues today.

(Source: Colin Waters et al (2016) The Anthropocene is functionally and stratigraphically distinct from the Holocene. Science.)

 

More to Explore:
The Anthropocene is functionally and stratigraphically distinct from the Holocene
‘Case is made’ for Anthropocene Epoch
Marks of the Anthropocene: 7 signs we have made our own epoch
Human impact has created a ‘plastic planet,’ research shows

 

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