The Anthropocene, Geologic Event or Geologic Epoch? Event, Says the Subcommission on Quaternary Stratigraphy

     Recognition of the Anthropocene as a geological epoch to be included on the geological time scale was rejected in March 2024 by the Subcommission on Quaternary Stratigraphy (SQS) after 15 years of lobbying in favor of that recognition by the Anthropocene Working Group (AWG).

     While there is no doubt that humans have been changing the biosphere, including the geosphere, for millennia, and with population growth that influence has grown exponentially, at this point in time it is just an event. My own argument for keeping it as an event rather than an epoch at this time is simply that on a geological time scale, we have not been influencing the biosphere very long and have especially not been the dominant influence for very long at all. After 1900 but mostly since 1950, less than a mere century ago, our influence increased dramatically. At some point, we may be able to ascribe the Anthropocene as a geologic epoch, but that time is not now. Maybe in another 100 years? I don’t know really. That’s my quickly assembled argument. Better arguments follow.

     Apparently, there are some who want the designation of an Anthropocene Epoch not for strictly scientific reasons but seemingly for political reasons. The question has been asked whether this designation is really useful or important to science in one way or another. I would say probably not. Those who want it designated epoch to support their policy arguments are not really interested in the science of it, I would argue, but only in getting what they see as policy endorsement.

     AWG proposed that an Anthropocene epoch began in the mid-20th century when nuclear weapons tests began to leave radioactive fallout across the globe. The Quaternary geologic period began 2.6 million years ago and the SGS is charged with deciding whether there should be any changes in the framework. Some at the SGS thought that the proposed epoch was too limited since humans have been affecting the biosphere for much longer than the mid-20^th century. The AWG selected Lake Crawford in Canada as the type-geologic site for the Anthropocene based on an analysis of lake sediment cores. Microplastics, evidence of fossil fuel combustion, and a measure of radioactive plutonium from nuclear weapons tests can be found in the sediments.

 

 

     AWG picked 1952 as the starting point of the Anthropocene based on nuclear fallout from hydrogen bomb tests. The AWG will continue its work to promote that the Anthropocene should be deemed a geologic epoch. The International Union of Geological Sciences (IUGS), of which the SQS is a part, explained the AWG stratigraphic proposal as follows:

 

“The proposal was that the Anthropocene should indeed be a new chronostratigraphic unit; that it should be of series/epoch status; that it should begin not in the mid-18th century but rather in the 20th century (~1950) where a range of proxy indicators marked a significant increase in human impact (the ‘Great Acceleration’); and that it should be underpinned by a GSSP. A GSSP or a Global Stratotype Section and Point indicates the internationally-recognised base of a chronostratigraphic unit, marked by a ‘spike’ in a succession, usually of rock, and is the start of geological time for that unit”

 

     Breakthrough Institute’s Alex Trembath suggested in an article at the end of June that several advocates of an Anthropocene epoch carried an ‘ideological slant’ that did not take kindly to someone from Breakthrough saying that there were good parts to the human age as well as bad. People such as Naomi Oreskes, a Harvard science historian and climate advocate, journalist Elizabeth Kolbert, and soil scientist and planetary boundaries pioneer Johan Rockstrom are either members of the AWG or advocates of its positions. Kolbert, whose book: The Sixth Mass Extinction I reviewed here, describes herself as an Anthropocene partisan. The AWG started out as strictly as a small group of geoscientists but later grew to include members from geography, ecology, archaeology, the humanities, and the legal community, eventually including over 30 members. The SQS decided to acknowledge the Anthropocene as a geologic event. I agree with this designation as probably do most of the Breakthrough Institute folks. Trembath writes:

“This was the right decision. As the ecologist and Breakthrough Senior Fellow Erle Ellis, a former member of the AWG, has explained for years, the Anthropocene is better thought of as a geologic “event,” similar to the Great Oxygenation Event that occurred over 2 billions years ago. What’s more, as Ellis and many others have pointed out, the very debate about the Anthropocene revealed the impossibility of establishing a hard stratigraphic demarcation of humanity’s footprint. The proposed inciting incidents for the Anthropocene spanned, literally, a million years, from homo sapiens’ unique mastery of fire to the dawn of agriculture (which coincides with the start of the Holocene) to the Columbian Exchange to the Industrial Revolution to the dispersion of radioisotopes and microplastics in the postwar twentieth century.”

“The purpose of the stratigraphic Anthropocene, to its partisans, was explicitly to advance an anti-consumerist and anti-industrial ecological politics…”

     It was atmospheric chemist, Paul Crutzen who first proposed the Anthropocene in 2001. AWS was founded in 2009 to promote the idea of changing the geologic designation. An explanation by the International Union of Geological Sciences (IUGS) gives three critiques of recognizing an Anthropocene epoch. The first is that it is not an accurate start point since our influence started hundreds of thousands of years ago. The second is that the time interval is so small, similar to my argument, just a blip in geologic time. The third is that designating the Anthropocene as an epoch does not meet the stratigraphic definition requirements. IUGS explains:

 “A third cause for concern is that the human effects on global systems are time-transgressive and are also spatially and temporally variable, so that their onset cannot be adequately represented by an isochronous horizon as reflecting a single point in time. An alternative narrative has therefore arisen in which the Anthropocene is not considered as a series/epoch (i.e., a chronostratigraphic unit and the corresponding geochronologic unit) but rather as an event, similar to the great transformative events in Earth history such as the Great Oxygenation (2.4-2.1 Ga), the Cambrian Explosion, or the Great Ordovician Biodiversification events.”

“None of these major transformative events in Earth history are represented as chronostratigraphic units, and hence there has been no requirement for formal ratification. If so, the Anthropocene could be considered as an informal non-stratigraphical term.”

Below is a chart of geological and historical timelines including important events and developments.

 

Basically, this whole issue is a one of classification. Whether epoch or event is not really very important but for the sake of an orderly and consistent framework, its designation should be stratigraphically consistent with other designations.

     The SQS is made up of the world’s experts on Quaternary geology. The tallies for the recent vote: 12 votes to reject the Anthropocene as an epoch, 4 votes in favor, 3 abstentions, and 3 non-voters. Thus, the motion was defeated soundly with 75% of SQS votes in favor of rejection.

     Of course, as the IUGS acknowledges the concept of the Anthropocene will continue to be used as before. The only change is that it will not have a precise scientific meaning as a geologic epoch, as proposed by the AWG. Trembath emphasized the political intent of the AWG advocates seeking stratigraphic validation, writing a bit harshly perhaps:

 

“The scholars who advocated a hard end to the Holocene did so relying on shabby science for a transparently political agenda. One or the other might be excused - science is always messy, and never totally apolitical. But the combination gave good reason for the IUGS to reject their recommendation. The rest of us, meanwhile, should breathe a sigh of relief, as this decision marks a break with the long history of outsourcing sociocultural questions of value to the ideological scientism of naturalists, ecologists, and conservationists. Because at the end of the day, the question of whether modern humanity’s existence is a good thing or not—whether we can make a Good Anthropocene—is a question for society, not stratigraphy.”

    

     Apparently, Johan Rockstrom took offence to the decision to reject, going so far as to blame geologists of being on the wrong side of scientific evidence, particularly on climate change. I have critiqued Rockstrom’s planetary boundaries framework and reviewed his 2015 book Big World, Small Planet: Abundance Within Planetary Boundaries.

 

Leigh Phillips’ Evolutionary-Ecological Novelty

     In August 2024 Breakthrough Institute’s Leigh Phillips published a fascinating and thought-provoking article: Moving On from the Anthropocene: ‘Recognizing the Anthropocene as a Geological Event Allows for a Radically Humanist Approach to Climate and the Environment.’ The author considers Ellis’s examples, the Great Oxygenation Event, the Great Ordovician Biodiversity Event, and the Devonian vascular plant conquest of land and compares them to the event of human impacts. Phillip’s quest is premised on an idea of evolutionary-ecological novelty:

“Recognizing the Anthropocene as a geological event prompts a philosophical-scientific framework that transcends mere comprehension of the profundity of what we have wrought to truly reckon with the deep-time novelty of what we are.”

Those geological events of profound change in the past, such as mass extinctions, changes in the atmosphere, on land, and in the oceans, had immensely negative effects. They also shaped us evolutionarily as selection pressures, with both negative and positive results. The Great Oxygenation Event was one of the greatest mass extinctions. However, as oxygen metabolism it became an evolutionary revolution, a change to species that improved capabilities. Phillips refers to it as an “energetic revolution” that “permitted the emergence of multicellularity.”

The author explains the Devonian novelty:

 “…the late Devonian novelty is the vascularization of plants—the development of true roots, stems, branches and leaves, which resulted in break-up of rocks by roots, the first soils, and, as a result, a flood of nutrient “pollution” washing into the oceans. This nutrient flood into the oceans resulted in large algal blooms that triggered the Late Devonian mass extinction. These pulses of die-off amounted to a loss of perhaps three quarters of species. But had this event not occurred, there would be no lush, green terrestrial ecosystems that we humans love and depend on.”

It was life itself that initiated these two events: cyanobacteria initiated the Great Oxygenation and plants initiated the Late Devonian mass extinction event. The third of Ellis’s comparisons, the Great Ordovician Biodiversity Event, was not initiated by life. It was not biotic, but abiotic, being initiated by a massive regional volcanism that filled the atmosphere with greenhouse gases changing the climate as well as selection pressures such as “radically more complex food webs, an increase in predator diversity, and much more competition for resources.”

     Phillips then asks, “What is the evolutionary-ecological novelty of the Anthropocene event?” “What is its new selection pressure?” many in the AWG consider that it was the Industrial Revolution and the coinciding advent of fossil fuels. However, most in the AWG settled on the Great Acceleration, the increase in energy and material consumption after WWII. Others have argued unconvincingly that it was political or economic, with capitalism, modernity, the Enlightenment, or even the impulse to control nature. The author quips:

“If the Great Oxygenation Event’s evolutionary-ecological novelty is ultimately the advent of photosynthesis, and the late Devonian event’s novelty is the advent of plant vascularisation, then it follows that the evolutionary-ecological novelty of the Anthropocene Event is the advent of the advanced sapience of the genus Homo, particularly in the Homo sapiens lineage (but not exclusively).”

The author goes through the biological idea of dual inheritance, genetic and cultural, to arrive at the idea that the novelty is novelty itself, or constant novelty. I was a bit skeptical when I first read this, but it makes more sense to me now. Cultural inheritance gives us the ability to constantly improve our technologies for survival, prosperity, and reproductive opportunity, the key evolutionary goals. This allows us to construct our niche in a process that tweaks our overall survivability. The author suggests that the human collective events such as the use of fire and the emergence of cities and agriculture, are “all mere social epiphenomena atop a deeper evolutionary-ecological novelty.” That novelty is made up of our new knowledge (sapience is the word he uses), dual inheritance, and constant novelty. He quips:

“We can, in principle, through decoupling of economic development from negative environmental impacts, ensure that the evolutionary-ecological novelty of constant novelty does not deteriorate the ecosystem services that we and the species we care most about depend upon.”

We can optimize our impacts on the environment by minimizing them. Therefore, he argues we can use this idea of our evolutionary-ecological novelty as a way to improve ourselves, resulting in an environmental humanism that is sensible and potentially successful, both evolutionarily and ethically.

     In any case, it is a fascinating article well worth a read here that should be considered important.  

 

 

References:

Moving On from the Anthropocene. Recognizing the Anthropocene as a Geological Event Allows for a Radically Humanist Approach to Climate and the Environment Leigh Phillips. The Breakthrough Journal. August 8, 2024. Moving On from the Anthropocene - The Breakthrough Journal (substack.com)

Geologists reject the Anthropocene as Earth’s new epoch — after 15 years of debate. Alexandra Witze. Nature. March 6, 2024. Geologists reject the Anthropocene as Earth’s new epoch — after 15 years of debate (nature.com)

Long Live The Good Anthropocene: A victory for science over scientism. Alex Trembath. The Breakthrough Journal. June 28, 2024. Long Live The Good Anthropocene | The Breakthrough Institute

Scientists Reject Proposal to Define the Anthropocene, a Geological Age Marked by Human Activity. Will Sullivan. Smithsonian Magazine. March 6, 2024. Scientists Reject Proposal to Define the Anthropocene, a Geological Age Marked by Human Activity | Smithsonian (smithsonianmag.com)

The Anthropocene. International Union of Geological Sciences. March 20, 2024. Celebrating 50 Years of Earth Science for the Global Community (iugs.org)