Guest “geologizing” by David Middleton
The Anthropocene Working Group (AWG) was established in 2009 to see if there was a way to geologically differentiate an Anthropocene Epoch from the Holocene Epoch. The notion has always been preposterous because the only true difference between the Holocene and the preceding Pleistocene Epoch is the impact of humans on the planet. Otherwise, the Holocene has just been a run of the mill interglacial stage, geologically indistinct from the prior Pleistocene interglacial stages. After thirteen years, the AWG is finally prepared to present a recommendation for an official Global Boundary Stratotype Section and Point (GSSP), also known as a “golden spike.” GSSP’s are stratigraphic markers that define the beginning and/or end of a geologic time period.
Scientists say they’ve found a site that marks a new chapter in Earth’s history
By Katie Hunt, CNN
Published 1:31 PM EDT, Tue July 11, 2023
CNN —
Scientists have identified the geological site that they say best reflects a proposed new epoch called the Anthropocene — a major step toward changing the official timeline of Earth’s history.
The term Anthropocene, first proposed in 2000 to reflect how profoundly human activity has altered the world, has become a commonly used academic buzzword uniting different fields of study.
“When it’s 8 billion people all having an impact on the planet, there’s bound to be a repercussion,” said Colin Waters, an honorary professor…
[…]
The AWG, a group currently comprised of 35 geologists, has been working since 2009 to make the Anthropocene part of Earth’s official timeline. The group determined in 2016 that the Anthropocene epoch began around 1950 — the start of the era of nuclear weapons tests, the geochemical traces of which can be found around the world.
[…]
Birthplace of the Anthropocene
For the Anthropocene, the proposed golden spike location is sediment cored from the bed of Crawford Lake that reveals the geochemical traces of nuclear bomb tests, specifically plutonium — a radioactive element widely detected across the world in coral reefs, ice cores and peat bogs.
[…]
The AWG will present a proposal to make the Anthropocene official to the Subcommission on Quaternary Stratigraphy later this summer. If the subcommission’s members agree with a 60% majority, the proposal will then pass on to the International Commission on Stratigraphy, which will also have to vote and agree with a 60% majority for the proposal to move onward for ratification. Both bodies are part of the International Union of Geological Sciences, which represents more than 1 million geoscientists around the world.
A final decision is expected at the 37th International Geological Congress in Busan, South Korea, in August 2024.
[…]
The odds of the Anthropocene being ratified as a geologic epoch are slightly lower than…
Stan Finney, an actual professor of geology, and Secretary General of the International Union of Geological Sciences summed it up best…
He also feels that the push to officially recognize the Anthropocene may, in fact, be more political than driven by on-the-ground geology. The term was coined in 2000 not by a geologist but by the late atmospheric chemist and Nobel laureate Paul Crutzen — apparently in off the cuff remarks at a conference.
Finney said it’s more accurate to describe humanity’s profound impact on Earth as an ongoing geological event rather than a formal epoch with a precise global start date. It’s also possible, he said, that stratigraphers may decide that the Anthropocene doesn’t rise to the level of epoch, but it could be the fourth age of the Holocene — the much less catchy Crawfordian Age.
Finney and Edwards outlined many of the misleading, if not outright false, statements that Anthropocene proponents have made in this GSA article, particularly noting the political nature of their advocacy.
Political Statement
When we explain the fundamental difference of the Anthropocene from the chronostratigraphic units established by the International Commission on Stratigraphy to proponents for its recognition, they often reply that the human impact on the Earth system must be officially recognized, if for no other reason than to make the public and governmental agencies aware of that impact. Or, as the editorial in Nature (2011) argued, official recognition would encourage cross-disciplinary science and a “mindset” to understand and to take control of the current transformation. However, it is political action that is required to meet the ultimate goals of ameliorating human impact, which raises the question of the ICS making a political statement. Pope Francis has spoken out about the human-induced impact on the Earth system—so too have leaders of many nations, the United Nations, and numerous non-governmental organizations. In California, Governor Jerry Brown has initiated and promoted many legislative actions with the goal of ameliorating human-induced impact. Is the role of the ICS to make such a political statement? Would official recognition of the term Anthropocene as a unit of the ICS Chart realistically have any effect on promoting cross-disciplinary science or recognizing that we are in the driver’s seat as Nature editorialized? Or, is that not already the case?
The evolution of vascular land plants and their spread across the continents from late in the Devonian to early in the Permian completely altered Earth’s surface, left a significant stratigraphic record, and dramatically altered CO2 and O2 concentrations in the atmosphere and oceans far greater than humans are projected to do (Berner and Canfield, 1989; Berner, 1998). Yet there is no drive to name a unit in the ICS Chart that formally recognizes that profound and irreversible change to the Earth system. Perhaps promotion of the Anthropocene is anthropocentric as well as political?
The “Atomic Age,” a term coined by The New York Times journalist William L. Lawrence in September 1946, has an identical boundary and content to the Anthropocene proposal of Zalasiewicz et al. (2015). By rights, the Atomic Age has nomenclatural priority. If the Anthropocene is not a political statement, those who value priority should prefer the Atomic Age.
This bears repeating:
If the Anthropocene is not a political statement, those who value priority should prefer the Atomic Age.
The CNN article goes on to note that folks farther to the left than the AWG don’t like the term Anthropocene because only capitalism is to blame for everything bad that has ever happened in human history.
Others object to the term Anthropocene because it implicates all of humanity in the activity that has irrevocably altered the planet. Some researchers say the changes are the doing of a powerful and elite minority and that the epoch would be better named the Capitalocene.
If you want a fast track to a migraine headache, open up the Capitalocene link and try reading the gobbledygook.
These people a certifiably bat schist crazy…
Previous studies of the lake’s sediments revealed two major periods of change: one lasting from the thirteenth to fifteenth century, when Indigenous peoples speaking the Iroquois language lived in the area, and another beginning in the nineteenth century, marking the arrival of European colonists. The biggest number of changes appear in layers from the middle of the twentieth century, a period dubbed the great acceleration3 of human impacts.
Those layers document the rise of radioactive plutonium fallout from nuclear bomb testing; the working group chose that rise as the marker for the Anthropocene’s start. Cores taken at Crawford in 2019 and 2022 showed that plutonium traces increased in the early 1950s, but McCarthy and colleagues have collected an extra core this year to perform a more detailed analysis. Depending on their findings, the year proposed for the golden spike could be 1950 — when several environmental changes accelerated — or 1952, when plutonium levels rose sharply. “The difference is 2 millimetres, but philosophically it matters,” McCarthy says. If 1950 is chosen, the golden-spike core will be the one gathered in 2019, which resides at the Canadian Museum of Nature in Ottawa. If 1952 is chosen, it will be this year’s core.
No more cores
McCarthy does not plan to collect cores at Crawford Lake again. The lake is sentient according to Indigenous groups who live or have lived in the area, and taking samples from the lake violates that personhood.
In the coming months, the working group will submit three ideas to the Subcommission on Quaternary Stratigraphy. First, Crawford Lake should serve as the golden spike for the Anthropocene’s start, with the year to be determined. Second, the Anthropocene should become a geological epoch ending the Holocene; the name of its first age could be the Crawfordian age. And finally, some of the eight sites that didn’t win the golden-spike designation could serve as supplementary sites to help define the Anthropocene across geological environments.
I don’t know which of the following is more laughable:
- Debating whether or not a geologic time period started in 1950 or 1952.
- An Epoch that’s only 6-8 years longer than I’ve been alive.
- Having a “golden spike” that won’t be there in a few million years.
- Declaring the “golden spike” off limits to future evaluation because it would violate the lake’s “personhood.”
- Spending nearly 20% of a geologic time period, looking for evidence that it exists… This is like taking 3.2 million years to find evidence that the Miocene Epoch deserved to be differentiated from the preceding Oligocene Epoch. Geologic time refers to periods of hundreds of thousands to hundreds of million years, not hundreds of years… Much less seven decades.
Plutonium is not forever
The primary basis for starting the proposed Anthropocene Epoch around 1950 is the presence of plutonium in sediments, coral reefs and ice sheets.
Plutonium is a radioactive metallic element with the atomic number 94. It was discovered in 1940 by scientists studying how to split atoms to make atomic bombs. Plutonium is created in a reactor when uranium atoms absorb neutrons. Nearly all plutonium is man-made.
Plutonium predominantly emits alpha particles – a type of radiation that is easily stopped and has a short range. It also emits neutrons, beta particles and gamma rays. It is considered toxic, in part, because if it were to be inhaled it could deposit in the lungs and eventually cause damage.
There are five “common” isotopes of plutonium, Pu-238, Pu-239, Pu-240, Pu-241, and Pu-242. These are all “fissionable” – the atom’s nucleus can easily split apart if it is struck by a neutron.
The different isotopes have different “half-lives” – the time it takes to lose half of its radioactivity. Pu-239 has a half-life of 24,100 years and Pu-241’s half-life is 14.4 years. Substances with shorter half-lives decay more quickly than those with longer half-lives, so they emit more energetic radioactivity.
Like any radioactive isotopes, plutonium isotopes transform when they decay. They might become different plutonium isotopes or different elements, such as uranium or neptunium. Many of these “daughter products” are themselves radioactive.
239Pu has a very long half-life of 24,100 years. If you start out with 1 gram of 239Pu, in just over 1 million years, you would have a sample that is 99.99999999998% composed of 235U. While naturally occurring uranium-235 is uncommon, it does exist. Over a geologically meaningful time-span, the anthropogenic “fingerprint” would no longer definitively be of anthropogenic origin, assuming the sediment core was lithified and preserved in the rock record. At best, the dawn of the Anthropocene would be represented by an anomalous uranium isotope ratio.
A likely compromise
While the IUGS is unlikely to ratify an Anthropocene Epoch, they do seem to be open to recognizing it as “geological event” rather than a formal geologic time period.
In contrast to the definition of a new Series/Epoch of the GTS, the designation of a geological event has no such formalization procedures nor GSSP requirements. Yet, to designate the Anthropocene as a geological event would not decrease its significance in Earth’s history. In fact, it would place the Anthropocene with other great transformations of the Earth system. Consider the example of the Great Oxidation Event, which occurred roughly 2.4-2.1 billion years ago and demonstrates that humans are not the first organisms to contribute to a global transformation of Earth (Sagan, 2020). Before the Great Oxidation Event, Earth had a weakly reducing atmosphere in which oxidation was prevented. After cyanobacteria began to produce oxygen as the waste product of photosynthesis, atmospheric oxygen levels rose and radically changed the course of planetary development, including the evolution of multicellular life and the colonization of land following the development of an ozone layer (Schirrmeister et al., 2013). Despite its firm basis in stratigraphy (Buick, 2008; Eriksson and Cheney, 1992), the Great Oxidation Event is not used as part of the GTS but is recognized as a major transformative phase of the Earth system. The same is true for the Great Ordovician Biodiversification Event (GOBE), and for the continental invasion by land plants that transformed the Earth system and stratigraphic records during the Devonian Period (Le Hir et al., 2011; Dahl and Arens, 2020). These examples emphasize that geologic events are not points in time: they are significant happenings or occurrences that are heterogeneous over time and across the Earth.
I discussed thieir paper in more detail in this 2021 post.
We already have an Anthropocene. It’s called the Holocene and really doesn’t deserve its status as an Epoch. Apart from the phrase “mass extinctions,” this is a fairly reasonable characterization of the human-related geological event.
The entire discussion is kind of pointless. Even if humans do leave definitive proof in the rock record that we significantly altered the “Earth system”… Proof that outlives us as a species and is preserved in the rock record, long after we’re gone… Who’s going to see it? Space aliens? Whatever lifeforms evolve to replace humans?
But, it’s always enjoyable to ridicule these folks…
There’s also a problem with using the word element, “-cene.” The current naming convention applies “-cene” to Cenozoic Era epochs. Instead of the Anthropocene Event, I would call it, the Anthropolitan Event… Better yet… The Fabulous Anthropolitan Event!
References
Finney, Stanley C. & Lucy E. Edwards. “The “Anthropocene” epoch: Scientific decision or political statement?” GSA Today, 2016; 26 (3): 4 DOI: 10.1130/GSATG270A.1
Gibbard PL, Bauer AM, Edgeworth M, Ruddiman WF, Gill JL, Merritts DJ, Finney SC, Edwards LE, Walker MJC, Maslin M, Ellis EC. A practical solution: the Anthropocene is a geological event, not a formal epoch. Episodes 2022;45:349-357. https://doi.org/10.18814/epiiugs/2021/021029
via Watts Up With That?
July 13, 2023 at 08:56AM
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