Are We In The Anthropocene? No.

ResearchBlogging.org
Proposals to give the latter part of the present geological period (the Holocene) a new name … the Anthropocene … are misguided, scientifically invalid, and obnoxious. However, there is a use for a term that is closely related to “Anthropocene” and I propose that we adopt that term instead.

The pithy title of the paper making this proposal is “Are we now living in the Anthropocene” (sic: no question mark is included in this title, enigmatically).

It is not an entirely stupid idea. The paper argues that there are major changes of the type often used to distinguish between major geological time spans that are unique to the present day, so maybe there is an argument for a named period. The paper more specifically argues that these features are largely anthropogenic.

A case can be made for its consideration [of the Anthropocene] as a formal epoch in that, since the start of the Industrial Revolution, Earth has endured changes sufficient to leave a global stratigraphic signature distinct from that of the Holocene or of previous Pleistocene interglacial phases, encompassing novel biotic, sedimentary, and geochemical change. These changes, although likely only in their initial phases, are sufficiently distinct and robustly established for suggestions of a Holocene-Anthropocene boundary in the recent historical past to be geologically reasonable.

Why is this scientifically invalid? There are several reasons. The Anthropocene is minimally as scientifically valid as the Holocene, the bit of geological time that would be trimmed to make room for the Anthropocene. and the Holocene is not scientifically valid. The Holocene is a non-glacial period distinct from the previous Pleistocene because the Pleistocene is a glacial period. Or at least, that is more or less (I’m oversimplifying a bit) how things were conceived when these periods were defined. It turns out, however, that the Holocene is almost certainly just another interglacial during a longer epoch of periodically repeating and increasingly severe glacials.

This means that we are not in the Holocene, but rather, in the Pleistocene. Therefore, the proposal to call the present (and going back a short period of time) something different would rest on he argument that the defining factors of the Anthropocene are more determinative of geological epochal identity than the defining factors of the Pleistocene. And they are not. Glacial cycles are big powerful things that change every aspect of the biota, carve up huge areas of the earth, deposit enormous loads of sediment globally that would not otherwise (in the absence of glacial action) be deposited, change sea levels dramatically, and so on. The geological and biotic markings of the present century and the last … all the mucking around that humans are doing … is not demonstrably greater than, or even nearly equivalent to, the great changes wrought by glaciation.

Then, there is the scale problem. Geological periods are defined by changes that can not only be viewed from a great distance in time, but can’t be missed from so far away. It should be as reasonable to define a geological epoch as it is to note the existence of a mountain chain from many kilometers away. It might be that anthropogenic changes to the biota and the landscape are sufficiently blatant and long lasting to create a such a distinct distance, or they may not. The Holocene itself is invalid because it is too near-sighted (in time) of a concept, considering a mere several thousand years and calling it a distinct period. And we (well, they, I wan’t even born yet) got that totally wrong. How does a few centuries of observation translate into a valid geological periodization? It does not. It is possible that we can define a new period that begins about now (plus or minus in geological time). But those proposing the Anthropocene are several million years premature. They need to be more patient.

Finally, while anthropogenic effects cannot be used to define a new geological period, they have already, in my view, met or exceeded the minimal requirements to be considered a geological “event.” In particular, an extinction event, and in addition, a major biogeographical event. Never before has there been such a massive transfer of species … in all the Kingdoms of life … across otherwise separated continents. This massive, multi directional invasion, as well as the widespread harvesting of the plant life of certain major biomes (such as forests), have caused a mass extinction. Some of the prior mass extinction events have been much more severe than the present one, but perhaps not all. There is evidence that the present mass extinction event is only getting started. But unlike geological periodizaiton, which requires the perspective of millions of years to really evaluate, the reality and validity of a mass extinction event can be observed and verified in much less time.

Mass extinction by invasion and steady habitat loss, as opposed to mass extinction by massive volcanic eruption or extraterrestrial object impacts, will be very slow as mass extinction events go, but the relevant comparison here is between days or months on one hand to centuries on the other. We see that more vulnerable, or more targeted, biomes are well into the range of the highest levels of extinction rates. In Polynesia, about 90% of endemic bird species have gone extinct (varying greatly across the region) in the last 400 years. Birds are going extinct at an alarmingly high rate globally. I believe that there are entire biomes that have been wiped out long enough ago that the numerical contribution of these losses to the overall event are uncountable (this includes European temperate forests and seasonally dry African tropical forest).

I don’t think it is reasonable to define a new era called the Anthropocene. But I do think it is entirely scientifically valid to define an event that could be called the Anthropogenic Extinction.

I started out saying that the proposal of the Anthropocene is both scientifically invalid but also obnoxious. Well, it could be obnoxious simply because it is scientifically invalid. But there are other reasons. The main reason is that it is anthropocentric. “But wait,” you say, “It might not be a valid period, but the stuff the authors of that paper are talking about are human-caused, so why not call it ‘anthro-whatever whatever.’” But that, dear reader, would be yet another anthropocentric misconception.

To the extent that the events of the modern era, including over harvesting major biomes and global warming, are cause by human activities, it also has to be recognized, from a strictly evolutionary and biological point of view (as opposed to a human-centric point of view) that this is not a human event, but a multi-species event. Viewed from the perspective of a sentient being from another planet that has absolutely no human-like preconceptions and no way to directly relate to the point of view of any Earthling species … say a sentient being evolved from silica dust particles that that exist as dust-sized individuals organized in eusocial metabeings that are several Jupiters in size and that do not perceive light … humans are certainly not the only thing, or even the most common thing, in this picture. The authors of this paper argue, for instance, that human population size has skyrocketed in the last several thousands of years. But how? Why? Our little/big silica-beings would view this very differently. They would see the emergence, some 10,000 years ago, of fewer than a half dozen different forms of grass as dominant species, spreading across the planet at the expense of many other life forms. The spread of these grasses (rice, corn, wheat, etc.) is associated with, possibly facilitated by (but wait, these silica beings might not be adaptationists, so we should not put ideas in their dusty little brains) four and two legged, mobile warm-blooded things that tend the grasses, and in return, are fed by the grasses.

This may sound funny, but I’m not joking. Not even a little. Modern human societies do not exist outside of biology, and some of the most important aspects of our energetics as a species derive from very tight knit co evolutionary relationships with a variety of grasses, microbes, and a few other plants, and some animals. All this talk about recent, and possibly accelerated, human evolution all about this co-evolutionary relationship.

But I suppose I would not expect geologists to be keyed into that way of thinking.

But, obviously, while we may agree that there is an extinction event going on now, the same reasoning that tells us to avoid the anthropocentric terminology should caution us to not call this event the “anthropogenic extinction event.” So we need another name.

Most of the plants involved in this extinction event are either grasses or other Monocots (such as plantains). So this could be the Monocot Event. But since the rise of grasslands per se is actually a Miocene event, perhaps this could be the Monocot-Anthropoid Event. Clearly, more work is needed on coming up with a suitable term. Suggestions are welcome!


Zalasiewicz, J., Williams, M., Smith, A., Barry, T.L., Coe, A.L., Bown, P.R., Brenchley, P., Cantrill, D., Gale, A., Gibbard, P., Gregory, F.J., Hounslow, M.W., Kerr, A.C., Pearson, P., Knox, R., Powell, J., Waters, C., Marshall, J., Oates, M., Rawson, P., Stone, P. (2008). Are we now living in the Anthropocene. GSA Today, 18(2), 4. DOI: 10.1130/GSAT01802A.1

See also:

Pimm, S. (2006). From the Cover: Human impacts on the rates of recent, present, and future bird extinctions. Proceedings of the National Academy of Sciences, 103(29), 10941-10946. DOI: 10.1073/pnas.0604181103

This paper is also being discussed here:

Do we need a new geological epoch?

Just a blip of the geologic radar

Comments

  1. #1 Jason Failes
    January 31, 2008

    “Therefore, the proposal to call the present (and going back a short period of time) something different would rest on he argument that the defining factors of the Anthropocene are more determinative of geological epochal identity than the defining factors of the Pleistocene.”

    Yes, because we are certainly about to go right back into another severe glacial period (Is it inappropriate to insert an eye-rolling emoticon in a scienceblogs comment?)

    “Viewed from the perspective of a sentient being from another planet”…they would see one species clearing huge tracts of land and replacing it with uniform crops, herds, cities and other structures. If someone digs up this era in a few million years, it will read as a completely distinct era, not just in terms of direct contamination with heavy metals, synthetic chemicals, and naturally occurring substances in otherwise unnatural proportions, but also the telltale signs of what looks to be a severe climate change event currently on our horizon.

    I do agree that it is too soon to label, but why would human-level intelligence (and whatever comes later) have less of an effect over time?

  2. #2 Greg Laden
    January 31, 2008

    why would human-level intelligence (and whatever comes later) have less of an effect over time?

    1) human “intelligence” is not demonstrably the cause of the agricultural revolution. That is a self serving teleological anthrpocentric view held, I admit, by a lot of people, but not correct.

    2) It remains to be seen if humans will remain a factor after their own extinction, the exact timing of which is uncertain!

    I understand the political relevance of calling the present the Anthropocene, because it brings home the point and is supportive of self reflection as a species. I support that. But I think calling our effect an extinction event rather than a geological period serves that purpose much, much better. Don’t you think?

    What would an eye-rolling emoticon look like?

    %~)

  3. #3 Ian
    January 31, 2008

    Forget the Anthropocene – when does the Obscene start?!!

  4. #4 Ahcuah
    January 31, 2008

    I think you are right on with the “Anthropogenic Extinction” distinction.

    If the Anthropocene folks were consistent, they would also demand that we rename the Paleocene the “Chicxulubene”. (Or maybe the “Deccantrapsene”.)

  5. #5 BrianR
    January 31, 2008

    you say: “and the Holocene is not scientifically valid”

    Why? Just because it’s just an interglacial? Doesn’t matter. Look at the geologic time scale and all the divisions we break out have shorter durations the closer to the present. This is because we have better chronologic resolution, more context of paleo-conditions…basically, more information. I don’t think it’s a problem at all. For those doing Quaternary geology, it is extremely valuable to break out the time period since de-glaciation. We know way more about the current interglacial than any of the others. The time periods are NOT defined by how long they are. They are a function of resolution. The Holocene is 11 kyr, the Pleistocene is ~2 my, the Pliocene is ~4 myr, the Miocene is >15 myr, and so on. And they are all Epochs. Are those all scientifically invalid?

    You say: “But those proposing the Anthropocene are several million years premature. They need to be more patient.”

    Why several million years? Why is that the magic number? The Eocene Epoch is ~20 my long … should we wait that long?

    The boundaries for the distinct time divisions we’ve broken out are based on big changes in the record of the Earth’s history. It’s NOT based on how long they are.

    Like any historian, those that study Earth history have more information in the most recent time…I think it is not only valid but helpful to further subdivide if you have more information. We discuss the history of human civilization a few thousand years ago by century, but we break out the 20th century into smaller bits, essentially by decades. Is this invalid?

    The Holocene is perfectly valid…your argument for why it is invalid doesn’t hold up. Now, whether or not the last couple hundred years of changes deserves their own time division is another issue. I’m not completely sold on that just yet.

  6. #6 Greg Laden
    January 31, 2008

    Brian,

    You’ve assaulted my argument on the basis of length. Put that aside for a moment. The Pleistocene is a period of glacials and interglacials. We are in an interglaical of the Pleistocene. That is my main argument, and as a person who works in the middle-upper Pleistocene and Holocene, I can say with confidence that most people in the biz recognize that the Holocene is silly. You’re just not there yet.

    But, even if one wanted to consider length, the situation is the opposite of what you are indicating. I’ve not been precise in my use of terminology, but I’d better start now to make this clear. The major periods have varied in estimated length not because we have more resolution of the more recent times, but because we have an increasing resolution, and in fact a fairly even resolution at the level of major transitions, of earlier times. This has resulted, for instance, in a surprisingly long Paleozoic and a significantly shortened, even to the point of absurdity, Pliocene. And don’t even talk about the Villafrancan and what happened to that.

    Retaining the Holocene is convenient, and I have not actually proposed that we dump it. I merely propose that we see it for what it is … utterly silly. It exists by a definition that is utterly different than anything we use to define either the beginning of the Pleistocene or the sub divisions of the Pleistocene. It’s like telling people who live in unit 14B of a large apartment building that they live in a different house and expecting them to believe it!

    I totally agree, though, with the part of your comment where you totally agree with me.

  7. #7 BrianR
    January 31, 2008

    You say: “I can say with confidence that most people in the biz recognize that the Holocene is silly. You’re just not there yet.”

    So your argument is that the Holocene is “silly” but you don’t want to get rid of it? Do you want to call it something else? Or, we just recognize it and not do anything about it? I’m sorry if I’m “not there” yet, but as someone who works on both ancient and recent geologic problems, I find the Holocene division very useful. I guess I don’t understand your beef with the Holocene. Would you rather it be an Age of the Pleistocene Epoch? If so, then work towards changing it…simply complaining about silliness won’t change what you think is silly.

    You say: “…we have an increasing resolution, and in fact a fairly even resolution at the level of major transitions, of earlier times.”

    What do you mean “increasing”? Because we are learning more? Which earlier times? Into the Proterozoic? I disagree…we don’t have even resolution at all. But, perhaps i’m simply misunderstanding you.

    You say: “This has resulted, for instance, in a surprisingly long Paleozoic and a significantly shortened, even to the point of absurdity, Pliocene.”

    But, the Paleozoic is an Eon and the Pliocene is an Epoch … they are two divisions apart on the hierarchy (with Period in between). I don’t think it’s fair to compare them like you have in that statement.

    Perhaps I’m being nit-picky, but this is what scientists do…don’t read it as combative :)

  8. #8 llewelly
    January 31, 2008

    Review this article about the ‘long tail’ of carbon emissions (by David Archer).

    My model indicates that about 7% of carbon released today will still be in the atmosphere in 100,000 years

    Review Pleistocene carbon levels . Archer’s findings imply that CO2 levels will remain well above any level found in the last 400kyr, for a long time – possibily long enough to melt the Greenland Ice sheet, possibly enough to melt the West Antarctic Ice sheet. Would there be another glaciation after the meltiing of one or both of those great ice sheets? I agree that it is too early to tell, but those glaciations may well be over.

  9. #9 Greg Laden
    January 31, 2008

    Brian,

    Now, you are being silly. I am not comparing the paleozoic to the pliocene. I also do not need to go on a crusade to eliminate the holocene (well, the conception of the holocene, not the actual holocene) simply because I think it is silly. There are a lot of silly things in our methods of periodization and categorization.

    llewelly: Yes, it is too early to tell, but I personally doubt that the glaciations are over. But maybe. The factors that probably cause the frequent and periodic emergence of glacial cycles are definitely going to go away eventually, but since they are probably mainly things like mountain ranges and the positioning of continents, that is a time scale of tens of millions of years, but the extra carbon (indeed, the existence of humans, possibly) is something on the scale of, well, much less. So maybe we’ll even skip two glaciations.

  10. #10 BrianR
    January 31, 2008

    Hmmm…but…you did compare the Paleozoic and the Pliocene.

    You said:
    “This has resulted, for instance, in a surprisingly long Paleozoic and a significantly shortened, even to the point of absurdity, Pliocene.”

    It’s entirely possible I’m misunderstanding you…I’m just asking for clarification.

    And, the other question was, do you think the Holocene should be an Age within the Pleistocene Epoch? Would that solve the issue?

  11. #11 Greg Laden
    January 31, 2008

    No problem, I can clarify. What I mean is this: The paleozoic has grown in length from its early conception. Also, the pliocene has gotten really short since its early conception.

    Well, the holocene could absolutely be an age in the Pleistocene, but more exactly, I think we should just be using the glacial stages. I think (but I could be wrong about this) that the Holocene is currently arbitrarily set at 10K, so that would not correspond to glacial stage numbering. But yes, not only would that solve the issue, but I think most people working at thousand year time scales in the late Miocene to the present (paleoanthropologists/archaeologists/glacial geologists) already think of it that way.

  12. #12 BrianR
    January 31, 2008

    aahh…okay, i see what you’re saying now re Paleozoic and Pliocene … this short style of e-communication can be difficult sometimes (at least for me).

    I agree…boundary between the Pleistocene and Holocene has always seemed weird to me. I often have to say something like latest Pleistocene to Holocene when trying to communicate about the time since LGM.