Anthropocene: Should we designate a new epoch? A geologist’s perspective

David Wharton-Street (UK)

Whatever your views, this is a subject that will not go away, and the concept of the Anthropocene is gaining more impetus and consideration as time goes by. In a nutshell, the Anthropocene has been proposed as a new third epoch of the Quaternary Period that directly relates to anthropogenic environmental impact on the Earth’s climate, land, oceans and biosphere, on a globally-recognisable scale. The Anthropocene would begin directly after the termination of the Holocene Epoch, but much debate and controversy currently relates to when exactly that date should be – should it begin thousands of years ago, perhaps relating to when our ancestors began widespread agricultural clearances? Should it begin with the Industrial Revolution or during the Second World War? In fact, some scientists even consider that it should begin as recently as the 1960s.

Interestingly, the term ‘Anthropocene’ only came into being very recently, in 2000, when a Dutch Nobel Prize-winning chemist named Paul Crutzen made an off-the cuff comment at a press conference and, just a few years later, the International Commission on Stratigraphy (ICS) Working Group on the Anthropocene was formed. Paul Crutzen rightly drew attention to mankind’s influence on the planet and the need to guide society through man’s impact (mostly deleterious). The designation of ‘Anthropocene’ as the epoch of ‘mankind’s influence’ is used to enhance the gravity of the way that man is destabilising earth’s natural systems.

However academically satisfying it is to promote a concept, it is quite a different matter to promulgate and enact solutions. The ensuing discussions have not been the prerogative of geologists. In fact, there is a case for geologists to be left out of the equation. There is increasing evidence of the effect man has had on earth during the Holocene; worthy of research and analysis by biologists, zoologists, meteorologists, oceanographers and so on, for the impacts of man lie clearly within these disciplines.

Having studied both geography and geology at Manchester and York Universities, respectively, I would promote the idea that the Anthropocene lies clearly within the all-engulfing discipline of geography. I studied human, historical, industrial and urban geography, geomorphology and soil science, climatology and geopolitics. Economic geography encompassed the challenges of the ‘first’ and ‘third’ world.

So why is there a problem of the Anthropocene becoming a geologist’s ‘cause célèbre’? A geologist researches and analyses the physical development and changes to the Earth over the past 4.6byrs. What has influenced those changes can be subjected to critical tests related to the laws of physics and chemistry, in other words, objective analysis. Many of the geological processes are happening in the present time and this increases the understanding of what has occurred in the past.

For the geologist, the Anthropocene is a case of reversing the discipline by looking into the future. Though analysis of trends into global warming, atmospheric gases, retreating ice sheets, sea level change, oceanic acidification, reduced biodiversity and extinction rates can all be accurately measured, the extrapolation into the future ceases to be objective analysis and becomes subjective judgement.

It is true that the rate of these changes has increased during the Holocene and relates to the effect of man on the environment. This leaves the geologist with two key issues to address:

1. What physical evidence will exist in sediments of man’s presence on Earth?
2. When did the Anthropocene commence, in terms of a GSSP (referred in populist literature as “the Golden Spike”)?

Man’s first presence is seen in widespread deforestation during the Neolithic and Bronze Ages, followed by grazing and the harnessing of plants for food production and man-made fire converted into increased atmospheric CO₂. Evidence is present in lake deposits, increased erosion and pollen analysis of sediments.

The next stage is the presence of “technofossils” – human artefacts in the form of shaped minerals, leather and worked-wood, then developing into bronze and iron products, present in deposits.

There is then a timescale progression of technological development from megaliths, construction of settlements and roads through to the mining and use of fossil fuels on a major scale; initiating the industrial revolution in the ‘first’ world and the creation of large industrial complexes and towns in the nineteenth century. But the significant changes have come in the twentieth century with the development of concrete and plastics, increased carbon, nitrogen and other ‘greenhouse’ gases in the atmosphere, population explosion and resultant sewage and waste products. Finally, there are the atmospheric effects of the atom bomb from 1945 onwards.

The challenge for the future is the degree of petrification of the remains of the above processes. We are not talking about a K/Pg event. So, yes, there is already evidence of microscopic layers of pollution in ice cores. It is probable that there will be isotopic evidence of chemical changes to the atmosphere and oceans. But will there be global evidence of a future eroded layer of man-made structures; and if so, how deep will it be to warrant geological significance. This is where the subjective judgement comes into play.

Gibbard recommends that the Anthropocene is viewed as a ‘cultural’ term (similar to the Neolithic) and not a geological epoch. The second problem for the geologist is to define the commencement of the epoch. From the human developments listed above, there are, and will continue to be, many propositions – all having merit – but unlikely to lead to a definitive solution.

The purpose of using the term Anthropocene goes back to Crutzen’s original concept. It is a means of drawing worldwide attention to what we are doing to our environment. The effects of the presence of man on Earth is a challenge to the enquiring mind, but, I believe, is short on real and achievable solutions in our geo-political world. Countries look after their own needs; as Donald Trump says: “America First”. The ‘first’ world has had its industrial revolution and the ‘third’ world can rightfully argue that it is now their turn.

Hence, economics become a major factor. The felling of vast tropical forests, the pollution of China’s industries and the conversion of virgin land to agriculture to feed the expanding world population are not going to be changed by eco-arguments. Thus, the terms eco-friendly, sustainability and ‘greener’ alternatives do not sit comfortably with either current realities or necessarily lead to beneficial action.

Situations only change when the consequences affect people directly and, in our consumer society, there is no evidence of ‘pressure for change’.

One should start from the basis of Crutzen’s tenet that “mankind is damaging the natural world and needs to be saved from itself by positive action, now.”

The other sciences have a distinct role to play in supporting this argument. They can present evidence, related to their discipline, to extrapolate historical data and update this on an annual basis. This shows the current trend, which can then be graphically projected into the future.

The discussion then centres on what will be the effect if this trend continues?

Geologists writing about the Anthropocene are, in effect, purely repeating (or high-jacking) the work done by other sciences. So, this raises two further questions:

1. Can geology provide added value to the discussion?
2. Has the geologist a role to play in defining the effects of global warming?

The key role is to present evidence of the effects of past global warming based on the geological record, but few geological papers on the Anthropocene have addressed this aspect. This is unfortunate because the present can learn significantly from the effect on past biota of global warming, particularly relating to the chemical composition of the sea, sea level changes and the effect on biota evolution, distribution and extinction.

The reader on the subject needs to make a decision as to whether there is any importance in evaluating a ‘start date’ for the Anthropocene and whether, in so doing, it adds any value. There are so many competing options for a GSSP that the matter may never be resolved geologically.

It is suggested that the concept and term ‘Anthrotechnic’ be a substitute for Anthropocene. This makes a lot of sense, in that the Holocene is already divided into Mesolithic and Neolithic: both based on technological development within mankind. The ‘Anthrotechnic’ would then become a logical sequence. This errs towards Gibbard’s thinking on the subject.

It also narrows down the period of defining the ‘Golden Spike’, which currently ranges from the period of deforestation in the Mesolithic to the Atom bomb in 1945. So, the next development after the Iron Age must be something significant in terms of technological development. In the geological record, there are traces of atmospheric lead in the Roman Age as a result of smelting. This Age witnessed a technological progress through the development of mining by humans – a factor that, over time, lead to the Industrial Revolution and the resultant significant growth in population.

As mankind’s need for and use of minerals (and thereby isotopes) are at the heart of this suggestion, it would also cover the technological development into the production of the atom bomb. I therefore opt for the ‘golden spike’ being placed during the Roman Age in Britain (earlier in southern Europe and earlier still in the Middle East (the cradle of civilisation), as a ‘diachronous’ boundary.

Whether there is a geological record within the laying down of current ice sheets and sediments adds nothing to the Crutzen’s tenet. It is solely of interest to the geologist, who is in a win-win situation for the following reasons.

1. If the Holocene is another inter-glacial, natural forces will overtake the effect of man, although the actions of mankind, in part, might delay any forthcoming ice age;
2. The world’s countries may adopt the Paris Accord and effect proper action, which would mean that the Anthropocene is a passing phase; and
3. Mankind might destroy itself or become extinct for other reasons.

So, who is going to be around in 20Ma plus to prove whether there is a distinct geological record of mankind’s presence on Earth and what form that record will take?

About the author

David Wharton-Street recently completed the Postgraduate Diploma on ‘The Geology of Yorkshire and northern England’ at the University of York, a two-year part-time programme run entirely online by distance learning: https://www.york.ac.uk/lifelonglearning/geology/. He can be contacted at: 4av9dws@gmail.com.

References

Crutzen, P. J. and Stoermer, E. F. (2000), The “Anthropocene”, Global Change Newsletter, 41, 17-18.

Gibbard, P. L and Walker, M. J. C. (2013). The term ‘Anthropocene’ in the context of formal geological classification, Geological Society of London, Special Publications.

Gibbard, P.L and Lewin, J (2016). Partitioning the Quaternary,

Quaternary Science Reviews, 151, 127-139.

Pearce, F. (2007). Tipping points in Climate Change. Boston: Beacon Press.

Pimm, S. L., et al. (2014). The biodiversity of species and their rates of extinction, distribution, and protection, Science 344(6187), 1-12.

Subcommission on Quaternary Stratigraphy (2016). Working Group on the ‘Anthropocene’. [Online]. Available at http://quaternary.stratigraphy.org/workinggroups/anthropocene/ [Accessed 27 April 2017].

van der Pluijm, B. (2014). Hello Anthropocene, Goodbye Holocene, Earth’s Future, 2, 1-3.

Visconti, G. (2014) Anthropocene: another academic invention? Fis. Acc. Lincei, 25, 381–392.

Waters, C. N. et al. (2016). The Anthropocene is functionally and stratigraphically distinct from the Holocene, Science, 351(6269), 1-26.
Zachos, J., Pagani, M., Sloan, L.,Thomas, E. and Billups, K. (2001). Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present, Science, New Series, 292. (5517), 686-693.

Zalasiewicz, J. (2008). The Earth After Us: What Legacy Will Humans Leave in the Rocks? Oxford: Oxford University Press.

Zalasiewicz, J., Williams, M., Haywood, A and Ellis, M (2011). The Anthropocene: a new epoch of geological time, Phil. Trans. R. Soc. A 369(1938), 835-841.

Zalasiewicz, J., Steffen, W., Leinfelder, R., Williams, M, and Waters, M. Petrifying Earth Process: The Stratigraphic Imprint of Key Earth System Parameters in the Anthropocene, Special Issue: Geosocial Formations and the Anthropocene Theory, Culture & Society, 1-22.