Consensus Science: Anthropocene Edition

Guest “This would actually be science by voting” by David Middleton

In my most recent post addressing the Anthropocene, one commentator became obsessed with the fact that in order for it to be adopted as a geological time period, at least three groups would have to approve it.

From Finney & Edwards, 2016.  “Workflow for approval and ratification of a Global Standard Stratotype Section and Point (GSSP) proposal. Extensive discussion and evaluation occurs at the level of the working group, subcommission, and International Commission on Stratigraphy (ICS) Bureau. If approved at these successive levels, a proposal is forwarded to the International Union of Geological Sciences (IUGS) for ratification. This process is also followed for other ICS decisions on standardization, such as approval of names of formal units, of revisions to the units, and to revision or replacement of GSSPs.”

Science by voting. How come they use 60% instead of 97% ?

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I never did figure out this commentator’s point. The voting is on whether or not to adopt a new subdivision in the geological time scale. It’s not voting on the science. The Anthropocene Working Group (AWG) will have to make a geologically coherent case that the Holocene Epoch has ended and an Anthropocene Epoch has begun. So far, they don’t even have a 97% “consensus” within the AWG.

Results of binding vote by AWG
Released 21st May 2019
Following guidance from the Subcommission on Quaternary Stratigraphy and the International Commission on Stratigraphy, the AWG have completed a binding vote to affirm some of the key questions that were voted on and agreed at the IGC Cape Town meeting in 2016. The details are as follows:

No. of potential voting members: 34 No. required to be quorate (60%): 21 No. of votes received: 33 (97% of voting membership)

Q1. Should the Anthropocene be treated as a formal chrono-stratigraphic unit defined by a GSSP?

29 voted in favour (88% of votes cast); 4 voted against; no abstentions

Q2. Should the primary guide for the base of the Anthropocene be one of the stratigraphic signals around the mid-twentieth century of the Common Era?

29 voted in favour (88% of votes cast); 4 voted against; no abstentions

Both votes exceed the 60% supermajority of cast votes required to be agreed by the Anthropocene Working Group as the official stance of the group and will guide their subsequent analysis.

Anthropocene Working Group

Key Phrases & Abbreviations

  • International Union of Geological Sciences (IUGS)
  • International Commission on Stratigraphy (ICS)
  • Subcommission on Quaternary Stratigraphy (SQS)
  • Anthropocene Working Group (AWG)
  • Global Boundary Stratotype Sections and Points (GSSP’s, AKA “Golden Spikes”)
  • INTERNATIONAL CHRONOSTRATIGRAPHIC CHART (Geological Time Scale)

The Anthropocene Working Group

The AWG is populated by climate change zealots, like Naomi Oreskes…

The AWG logo is a Mannian Hockey Stick!

It’s kind of surprising that after 10 years, they couldn’t come up with a 97% consensus. The AWG was formed in 2009. It took them 10 years to decide if they should put the base of the Anthropocene in the mid-20th century. I think this would be the first unit of geological time for which the decision of when it occurred preceded its geological basis.

Once they pick their representative marker, researchers working with the AWG need to gather enough evidence from around the world to convince the governing bodies of geoscience that they have found a truly reliable signal for the start of the Anthropocene. But some scientists argue that human activity has been shaping the planet for thousands of years, and that the working group has settled too quickly on the 1950s for the start of the proposed epoch. Erle Ellis, a geographer at the University of Maryland, Baltimore County, and an AWG member, has criticized the committee’s plans for designating the start of the Anthropocene. “The AWG decided the timing of the boundary before deciding on the marker, not the other way around,” says Ellis.

Hard evidence
In the end, it will be the rocks that have the final say.

Nature

AWG’s December 2020 newsletter outlined some of the sites they are considering for the Anthropocene’s “Golden Spike.” I may write up a post, exploring these in more detail… However, if “it will be the rocks that have the final say,” there aren’t a lot of actual sedimentary rocks that are less than 70 years old. Many of the Pleistocene sandstones in the Gulf of Mexico, aren’t truly “rocks” and they are quite a bit older than 70 years.

The AWG’s Appeal to Consensus

The AWG has analyzed a wide range of aspects of the Anthropocene concept, with the broad range of evidence being summarized by Zalasiewicz, Waters, Williams, et al. (2019). However, the AWG’s primary task is to assess the Anthropocene as a potential geological time (chronostratigraphic) unit, following the elaborate protocols stipulated by ICS and its parent body, the International Union of Geological Sciences (IUGS). The AWG is therefore progressing toward a proposal for a formal definition of the chronostratigraphic Anthropocene and has agreed that its isochronous base would be defined by stratigraphic signals associated with the Great Acceleration of the mid-twentieth century (Anthropocene Working Group, 2019).

There has, however, been a growing development of alternative and quite different understandings of the Anthropocene by both a small minority of AWG members and among several disciplines outside geology ranging from the natural and social sciences to the arts and humanities (see Ellis, 2018; Horn & Bergthaller, 2020; Thomas et al., 2020). The origin of these alternative understandings may stem back to the title of the Crutzen (2002) publication—“Geology of Mankind” and the by-line often used when referring to the Anthropocene, as “the human age” (e.g., Braje, 2015; Monastersky, 2015) or “Age of Humans” (H. Waters, 2016). This has led many to use the term Anthropocene to encompass the concept of all discernable human impacts on the planet—a much broader concept than Crutzen originally intended. In this broader view, the Anthropocene’s origin is diachronous, that is, time-transgressive and varies regionally, toward the time when Homo sapiens first gained collective capacities to change Earth’s ecology in unprecedented ways. The selection of key events when human societies first began to play a significant role in shaping the planet commonly reflects different disciplinary perspectives, both as regarding contested expertise within the sciences (Robin, 2013) and beyond them. For example, anthropologists and archaeologists may analyse the development of the first urban communities, or the development of agriculture either expressed in the sedimentary record as changing pollen records or inferred from modified atmospheric compositions. In contrast, as a geological task group in chronostratigraphy, the AWG investigates the Anthropocene in accordance with the mandate given to it by the SQS, as a potential geological time unit during which “human modification of natural systems has become predominant” (SQS, 2009), rather than locally or regionally significant.

This paper explores the diverse, but often overlapping, understandings of these “anthropocenes” and contemplates whether there is scope for such diverse meanings for the same term to coexist across disciplines, and how formally defining the Anthropocene as an epoch (in the geological sense) using the standard chronostratigraphic approach could contribute to and facilitate cross-disciplinary understanding.

Zalasiewicz et al., 2020

Translation: We’re having trouble with the geologically coherent reason for an Anthropocene Epoch… But all the cool kids are going full-Anthropocene! So let’s invoke “disciplines outside geology ranging from the natural and social sciences to the arts and humanities.”

Zalasiewicz et al, 2020 included an interesting graphical comparison of the Ediacaran-Cambrian boundary to the proposed Holocene-Anthropocene boundary:

Figure 1 from Zalasiewicz et al., 2020

How do we know Trilobites evolved approximately 521 million years ago? Because the oldest well-preserved Trilobite fossils are about 521 million years old. Any bets on how well-preserved the fossil evidence of our “33 megacities” will be 500 million years after we’re gone?

It’s also important to note that the anthropological, archaeological and cultural items listed to the right of the Neogene-Quaternary time scale were not used to define the subdivisions of the Holocene. The GSSP’s were in the rocks…

A series of votes
Like the stratigraphic record that the researchers are studying, the decision to officially designate the Anthropocene is multilayered. The AWG aims to present a final proposal identifying a mid-twentieth-century GSSP to its parent body, the Quaternary Subcommission of the ICS, by 2021. If approved, the proposal will be voted on by the ICS and will then proceed to the executive committee of the International Union of Geological Sciences (IUGS) for final ratification. Only if it passes all these hurdles will the Anthropocene officially become a new unit of the International Chronostratigraphic Chart, more commonly known as the Geological Time Scale. So far, all 65 GSSPs that have been ratified are from marine environments, except for the one marking the start of the Holocene, which uses a Greenland ice core.

The formal process has moved much more slowly than has popular culture, which has already embraced the Anthropocene and used the term on everything from record albums to magazine covers. But the AWG is clear that its mandate is to make decisions based on the stratigraphic record alone.

Not everyone is convinced it can do that yet. One sore point is that the working group made a decision on when to set the boundary, even though it had not yet settled on a golden spike in the stratigraphic record. “It is an imposition of ideas onto matter, shaping evidence to fit, but it should be the other way around,” says Matt Edgeworth, an archaeologist at the University of Leicester.

Edgeworth is a member of the AWG but voted against the decision to recognize the Anthropocene.

Nature

Glacial ice is a mineral… So, technically, continental ice sheets are rock formations.

A mineral is defined as a naturally occurring, homogeneous solid, inorganically formed, with a definite chemical composition( or range of compositions), and an ordered atomic arrangement. Water does not pass the test of being a solid so it is not considered a mineral although ice; which is solid, is classified as a mineral as long as it is naturally occurring. Thus ice in a snow bank is a mineral, but ice in an ice cube from a refrigerator is not. The only exception to this rule ( there always seem to be one ) is that mercury is considered a mineral (more a result of history – mercury was an important alchemical substance).

Minsocam

Rocks are composed of one or more minerals. A mineral is a naturally occurring, homogenous, inorganic substance having a definite chemical composition and fixed crystal structure. So, any naturally occurring ice, the crystalline form of water (H2O), can be considered a mineral. Now coming to the concept of glaciers, the glacial ice, like granite, can be considered a rock. Well, not exactly like granite which is an igneous rock (a rock formed by solidification of molten magma or lava), but more like a quartzite, a mono-mineralic metamorphic rock (a rock formed by alteration of a pre-existing rock) (Fig.2). The mineral in this case is ice.

Geoscience Education

Although, the choice of an ice core for a GSSP is probably not a good idea. As ice continues to accumulate on the Greenland Ice Sheet, the Pleistocene/Holocene boundary will soon (geologically) be deformed and eventually discharged. The Holocene Epoch shouldn’t even be an epoch.  It should be an interglacial stage within the Upper Pleistocene, rather than an epoch of equal stature to the Pleistocene. The Pleistocene-Holocene boundary, so clear in the NGRIP ice core, loses all of its uniqueness in Antarctic ice cores, which capture multiple Late Quaternary glacial-interglacial transitions.

If the Holocene Epoch is a mistake, the Anthropocene Epoch would be a joke…

The Anthropocene Is a Joke
On geological timescales, human civilization is an event, not an epoch.

PETER BRANNEN AUG 13, 2019

Humans are now living in a new geological epoch of our own making: the Anthropocene. Or so we’re told. Whereas some epochs in Earth history stretch more than 40 million years, this new chapter started maybe 400 years ago, when carbon dioxide dipped by a few parts per million in the atmosphere. Or perhaps, as a panel of scientists voted earlier this year, the epoch started as recently as 75 years ago, when atomic weapons began to dust the planet with an evanescence of strange radioisotopes.

These are unusual claims about geology, a field that typically deals with mile-thick packages of rock stacked up over tens of millions of years, wherein entire mountain ranges are born and weather away to nothing within a single unit of time, in which extremely precise rock dates—single-frame snapshots from deep time—can come with 50,000-year error bars, a span almost 10 times as long as all of recorded human history. If having an epoch shorter than an error bar seems strange, well, so is the Anthropocene.

[…]

The idea of the Anthropocene is an interesting thought experiment. For those invested in the stratigraphic arcana of this infinitesimal moment in time, it serves as a useful catalog of our junk. But it can also serve to inflate humanity’s legacy on an ever-churning planet that will quickly destroy—or conceal forever—even our most awesome creations.

[…]

Perhaps, someday, our signal in the rocks will be found, but only if eagle-eyed stratigraphers, from God knows where on the tree of life, crisscross their own rearranged Earth, assiduously trying to find us. But they would be unlikely to be rewarded for their effort. At the end of all their travels—after cataloging all the bedrock of the entire planet—they might finally be led to an odd, razor-thin stratum hiding halfway up some eroding, far-flung desert canyon. If they then somehow found an accompanying plaque left behind by humanity that purports to assign this unusual layer its own epoch—sandwiched in these cliffs, and embarrassed above and below by gigantic edifices of limestone, siltstone, and shale—this claim would amount to evidence of little more than our own species’ astounding anthropocentrism. Unless we fast learn how to endure on this planet, and on a scale far beyond anything we’ve yet proved ourselves capable of, the detritus of civilization will be quickly devoured by the maw of deep time.

[…]

Even worse for our long-term preservation—long after humanity’s brief, artificial greenhouse fever—we’re very likely to return to our regularly scheduled programming and dive back into a punishing Ice Age in the next half-million years. 

[…]

But what would we leave on the seafloor, where most sedimentary rock is made, where most of the fossils are, and where we have a slightly better chance of recording our decades-long “epoch” in the rocks? Well, many marine sediments in the fossil record accumulated, over untold eons, from the diaphanous snowfall of plankton and silt, at a rate of little more than a centimeter per thousand years. Given this loose metric (and our current maturity as a species), a dozen centimeters of muck seems an optimistic goal for civilization.

A dozen centimeters is a pathetic epoch, but epoch or not, it would be an extremely interesting layer. It’s tempting to think a whisper of atomic-weapons testing would remain. The Promethean fire unleashed by the Manhattan Project was an earth-changing invention, its strange fallout destined to endure in some form as an unmistakable geological marker of the Anthropocene. But the longest-lived radioisotope from radioactive fallout, iodine-129, has a half-life of less than 16 million years. If there were a nuclear holocaust in the Triassic, among warring prosauropods, we wouldn’t know about it.

The Atlantic

“Perhaps, someday, our signal in the rocks will be found”… Maybe the dreaded Plutonium, an evil man-made element.

242Pu, with its half-life of 375,000 years, decays into 238U, the most common naturally occurring Uranium isotope.

 Years  242Pu  238U
                             – 100.0% 0.0%
                 373,000 50.0% 50.0%
                 746,000 25.0% 75.0%
              1,119,000 12.5% 87.5%
              1,492,000 6.3% 93.8%
              1,865,000 3.1% 96.9%
              2,238,000 1.6% 98.4%
              2,611,000 0.8% 99.2%
              2,984,000 0.4% 99.6%
              3,357,000 0.2% 99.8%
              3,730,000 0.1% 99.9%
              4,103,000 0.0% 100.0%

It will be undetectable in less than 5 million years, replaced by “the most common isotope of uranium found in nature.”

Maybe cement and brick… What do you think cement and brick will weather into?

 Portland Cement
 Lime (CaO)  60 to 67%
 Silica (SiO2)  17 to 25%
 Alumina (Al2O3)  3 to 8%
 Iron oxide (Fe2O3)  0.5 to 6%
 Magnesia (MgO)  0.1 to 4%
 Sulphur trioxide (SO3)  1 to 3%
 Soda and/or Potash (Na2O+K2O)  0.5 to 1.3%

Brick
Silica (sand) – 50% to 60% by weight
Alumina (clay) – 20% to 30% by weight
Lime – 2 to 5% by weight
Iron oxide – ≤ 7% by weight
Magnesia – less than 1% by weight

What do you think the Earth’s crust is made out of? All of the raw materials in cement and brick came from the Earth’s crust.

In the end, it will be the rocks that have the final say.

Two years ago, the AWG was aiming to present a GSSP proposal by 2021.

The AWG aims to present a final proposal identifying a mid-twentieth-century GSSP to its parent body, the Quaternary Subcommission of the ICS, by 2021. If approved, the proposal will be voted on by the ICS and will then proceed to the executive committee of the International Union of Geological Sciences (IUGS) for final ratification. Only if it passes all these hurdles will the Anthropocene officially become a new unit of the International Chronostratigraphic Chart, more commonly known as the Geological Time Scale. So far, all 65 GSSPs that have been ratified are from marine environments, except for the one marking the start of the Holocene, which uses a Greenland ice core.

Nature

Now the AWG is shooting for 2024…

ICS statutes indicated that by the end of the current cycle the AWG would need to dissolve and at the invitation of the new SQS Chair to reassemble for a further four-year term. It was a great honour to be asked to step up from the groups’ position as Secretary to the role of Chair at this critical time of GSSP analysis, which is anticipated to be completed within this term and a proposal be formulated in time for IGC 2024. In preparation for this, the group reassembled with voting members (those with chronostratigraphic expertise suitable for voting on the GSSP proposals) and advisory members, who will continue our work on investigating the stratigraphic and wider meaning of the Anthropocene.

AWG December 2020 newsletter

If I didn’t know better (/SARC), I might be inclined to think they are waiting for Dr. Stanley Finney to step down from his post. In 2021, Dr. Finney began his second four-year term as the Secretary General of the International Union of Geological Sciences (IUGS), which would have to ratify an Anthropocene Epoch.

The utility of the Anthropocene requires careful consideration by its various potential users. Its concept is fundamentally different from the chronostratigraphic units that are established by ICS in that the documentation and study of the human impact on the Earth system are based more on direct human observation than on a stratigraphic record. The drive to officially recognize the Anthropocene may, in fact, be political rather than scientific.

Finney & Edwards, 2016

A modest proposal

No… Not that modest proposal. Let’s get rid of the Holocene Epoch. Demote it to an Age/Stage of the Pleistocene Epoch and call it the Anthropolitan: The fabulous age of metropolitan humans. Just don’t blink your eyes on your drive through geologic time… You’ll miss it.

‘Habitus’ (2013 – ongoing) is an art installation by Robyn Woolston (robynwoolston.com), commissioned by Edge Hill University, which announces the Anthropocene epoch, Vegas-style. AAPG Explorer.

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

Zalasiewicz, J., Waters, C. N., Ellis, E. C., Head, M. J., Vidas, D., Steffen, W., et al. (2021). The Anthropocene: Comparing its meaning in geology (chronostratigraphy) with conceptual approaches arising in other disciplines. Earth’s Future, 9, e2020EF001896. https://doi.org/10.1029/2020EF001896

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July 9, 2021 at 04:08AM

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