After seven years of deliberation, members of an international working group votedunanimously on Monday to acknowledge that the Anthropocene—a geologic time interval so-dubbed by chemists Paul Crutzen and Eugene Stoermer in 2000—is real.
The epoch is thought to have begun in the 1950s, when human activity, namely rapid industrialization and nuclear activity, set global systems on a different trajectory. And there’s evidence in the geographic record. Indeed, scientists say that nuclear bomb testing, industrial agriculture, human-caused global warming, and the proliferation of plastic across the globe have so profoundly altered the planet that it is time to declare the 11,700-year Holocene over.
As the working group articulated in a media note on Monday:
Changes to the Earth system that characterize the potential Anthropocene Epoch include marked acceleration to rates of erosion and sedimentation; large-scale chemical perturbations to the cycles of carbon, nitrogen, phosphorus, and other elements; the inception of significant change to global climate and sea level; and biotic changes such as unprecedented levels of species invasions across the Earth. Many of these changes are geologically long-lasting, and some are effectively irreversible.
These and related processes have left an array of signals in recent strata, including plastic, aluminium and concrete particles, artificial radionuclides, changes to carbon and nitrogen isotope patterns, fly ash particles, and a variety of fossilizable biological remains. Many of these signals will leave a permanent record in the Earth’s strata.
“Being able to pinpoint an interval of time is saying something about how we have had an incredible impact on the environment of our planet,” said Colin Waters, principal geologist at the British Geological Survey and secretary for the working group. “The concept of the Anthropocene manages to pull all these ideas of environmental change together.”
Indeed, the Guardian compiled more “evidence of the Anthropocene,” saying humanity has:
- Pushed extinction rates of animals and plants far above the long-term average. The Earth is now on course to see 75 percent of species become extinct in the next few centuries if current trends continue.
- Increased levels of climate-warming CO2 in the atmosphere at the fastest rate for 66m years, with fossil-fuel burning pushing levels from 280 parts per million before the industrial revolution to 400ppm and rising today.
- Put so much plastic in our waterways and oceans that microplastic particles are now virtually ubiquitous, and plastics will likely leave identifiable fossil records for future generations to discover.
- Doubled the nitrogen and phosphorous in our soils in the past century with our fertilizer use. This is likely to be the largest impact on the nitrogen cycle in 2.5bn years.
- Left a permanent layer of airborne particulates in sediment and glacial ice such as black carbon from fossil fuel burning.
Now, scientists must commence their search for the “golden spike”—explained in theTelegraph as “a physical reference point that can be dated and taken as a representative starting point for the Anthropocene epoch.” This could be found in anything from layers of sediment in a peat bog to a coral reef to tree rings.
“A river bed in Scotland, for example, is taken to be the representative starting point for the Holocene epoch,” the Telegraph reports.
The Guardian points out: “For the Anthropocene, the best candidate for such a golden spike are radioactive elements from nuclear bomb tests, which were blown into the stratosphere before settling down to Earth.”
However, Jan Zalasiewicz, a geologist at the University of Leicester and chair of the working group, told the paper that while “the radionuclides are probably the sharpest—they really come on with a bang,” humanity has left no shortage of signatures.
“We are spoiled for choice,” he said. “There are so many signals.”
According to the Telegraph, once one or more golden spike sites have been selected, a proposal for the formal recognition of an Anthropocene epoch will be made to a series of commissions, culminating at the International Union of Geological Sciences. The process is likely to take at least three years.
Media note: Anthropocene Working Group (AWG)
Please see the below notice for more information:
This international scientific body (that includes the University of Leicester geologists Jan Zalasiewicz, Mark Williams and honorary chair, the British Geological Survey geologist Colin Waters, and archaeologist Matt Edgeworth), has been active since 2009, analysing the case for formalization of the Anthropocene, a potential new epoch of geological time dominated by human impact on the Earth. The AWG is about to present its preliminary findings and recommendations at the International Geological Congress in Cape Town, at the same time indicating the range of voting opinion within the group on the major questions surrounding the Anthropocene. It will also map out a route towards a formal proposal on formalization, and indicate work that still needs be done to effect this.
Majority current opinion on the group indicates the following:
• The Anthropocene concept, as articulated by Paul Crutzen and Eugene Stoermer in 2000, is geologically real. The phenomenon is of sufficient scale to be considered as part of the International Chronostratigraphic Chart, more commonly known as the Geological Time Scale.
• Majority AWG opinion is for assignation as an Epoch/Series. This option is preferred over either a lower rank (e.g. Age/Stage, i.e. as a subdivision of the Holocene) or a higher rank such as a Period or Era. In such a step, and in common with all other geological time units, the Anthropocene would comprise both a ‘pure time’ unit (an Anthropocene Epoch) and an equivalent unit of strata (an Anthropocene Series).
- If the Anthropocene is adopted as an Epoch, this would mean that the Holocene has terminated, but that we remain within the Quaternary Period and Cenozoic Era.
• Human impact has left discernible traces on the stratigraphic record for thousands of years – indeed, since before the beginning of the Holocene. However, substantial and approximately globally synchronous changes to the Earth System most clearly intensified in the ‘Great Acceleration of the mid-20th century. The mid-20th century also coincides with the clearest and most distinctive array of signals imprinted upon recently deposited strata.
• Hence, the mid-20th century represents the optimal beginning of a potential Anthropocene Epoch (and, simultaneously, the base of the Anthropocene Series).
• Changes to the Earth System that characterize the potential Anthropocene Epoch include marked acceleration to rates of erosion and sedimentation, large-scale chemical perturbations to the cycles of carbon, nitrogen, phosphorus and other elements, the inception of significant change to global climate and sea level, and biotic changes such as unprecedented levels of species invasions across the Earth. Many of these changes are geologically long-lasting, and some are effectively irreversible.
• These and related processes have left an array of signals in recent strata, including plastic, aluminium and concrete particles, artificial radionuclides, changes to carbon and nitrogen isotope patterns, fly ash particles, and a variety of fossilizable biological remains. Many of these signals will leave a permanent record in the Earth’s strata.
• The Anthropocene beginning might conceivably be defined by a Global Standard Stratigraphic Age (GSSA), i.e. a numerical age that can be expressed as a calendar date such as 1945. Or more, conventionally it could be defined by a Global boundary Stratotype Section and Point (GSSP), which is more colloquially a ‘golden spike’, and is a physical reference point in strata at one carefully selected place. Majority opinion on the AWG is to seek and choose a candidate GSSP, as this is the most familiar and widely accepted method of defining geological time units.
• The AWG has already begun the process of identification of potential GSSPs, by initial analysis of the general environments in which the best combinations of stratigraphic signals may be found (e.g. undisturbed lake or marine sediments, annually banded coral skeletons, polar snow/ice layers, speleothems and so on).
• This will lead to selection of sites for sampling and further analysis, to provide full descriptions of relevant signals in the strata, a process that we hope will lead to the identification of one or more suitable candidate sites for a GSSP. We would hope to complete this process over the next 2-3 years.
• This would then form the basis for the preparation of a formal proposal, to our immediate parent body, the Subcommission on Quaternary Stratigraphy (SQS), on defining a formal Anthropocene unit. If the SQS recommends this by supermajority vote, the proposal will go on to its parent body, the International Commission on Stratigraphy (ICS) to be voted on, with any vote in favour still needing to be ratified by the Executive Committee of the International Union of Geological Sciences (IUGS).
• If all of these conditions can be fulfilled, then the Anthropocene would become a formal part of the Geological Time Scale.
Results of AWG Vote (35 members):
- Is the Anthropocene stratigraphically real? For: 34, Against: 0, Abstain: 1
- Should the Anthropocene be formalised? For:30, Against: 3, Abstain: 2
- Hierarchical level of the Anthropocene? Era: 2, Period: 1.5, Epoch: 20.5, Sub-epoch: 1, Age: 2, Sub-age: 0, None: 1, Uncertain: 3, Abstain: 4
- Base/beginning of the Anthropocene? ~7ka: 0, ~3ka: 1.3, 1610 Orbis: 0, ~1800: 0, ~1950: 28.3, ~1964: 1.3, Diachronous: 4, Uncertain: 0, Abstain: 0
- GSSA .v. GSSP? GSSP: 25.5, GSSA: 1.5, Uncertain: 8
- What is the Primary Signal? aluminium: 0, plastic: 3, fuel ash particles: 2, carbon dioxide concentration: 3, methane concentration: 0, carbon isotope change: 2, oxygen isotope change: 0, radiocarbon bomb spike: 4,Plutonium fallout: 10, Nitrate concentration / nitrogen isotope change: 0, Biostratigraphic: extinction/ assemblage change: 0, Other (lead, persistent organic pollutants, technofossils): 3, Uncertain: 2, Abstain: 6.