Laelaps

Just a blip of the geologic radar

[Note: For fuller and more technical summaries of the Anthropocene and why it just doesn't fit (at least not yet), please read Chris' and Greg's posts. Likewise, naming new periods of time for perceived changes in our species or our impact in the world isn't anything new, i.e. the older concept of the noosphere (which I will write more about soon)]

Every few years it seems that the concept of the “Anthropocene” rears its ugly head again, the general idea being that we are now in a new geologic epoch defined by changes that our species has inflicted on the earth. The term is essentially tied to the Industrial Revolution, so from the perspective of Deep Time we’ve really only just begun to change things (and this, as I’ll argue, is why our impact on the environment is better understood as an event rather than an epoch). I first encountered the term last semester when I took a “Soils and Society” course in which the professor really tried to drive home that we were now in the Anthropocene, and even though I knew it didn’t quite fit I valued my test score high enough to just go along on the exams. (Is it just me or do many of the main proponents of making the Anthropocene a valid geologic epoch appear to be soil scientists?)

While the attachment of the moniker to our current age might be alluring given the ecologic havoc we’ve inflicted on the planet, in all I think it’s a bad move (more of a PR stunt than a rigorous scientific idea). How long is the hypothetical Anthropocene going to last? A million years? (And that’s being generous.) If anything our effect on this planet is probably going to appear more as a quick geologic event when the geologists of the future (if such creatures there be) look at the strata, so the concept of the Anthropocene epoch just doesn’t fit in with the way the geologic timescale is constructed. Indeed, geologists construct and debate the geologic timescale based upon evidence from the geologic record (including fossils), so while we might eventually be able to mark the beginning of an Anthropocene we certainly can’t do it now. If our destructive powers are as great (or greater) than we’ve feared, the Anthropocene might only last a few centuries before we destroy ourselves (remember, the starting point isn’t marked by a more distant event like the Pleistocene mass extinctions but rather by the Industrial Revolution), so naming an epoch for such quick destruction does not fit in with how the geologic time scale is constructed and understood.

The problem, as Brian points out at his blog Clastic Detritus, is that oftentimes get the association between geologic ages and the phenomena that signal transitions confused. The end of the Cretaceous is marked by the extinction of many varieties of organisms; the organisms did not reach some temporal limit and went extinct because their time was literally up. Will Cuppy, in the book How to Become Extinct humorously pointed out this fallacy with the line “The Age of Reptiles ended because it had gone on long enough and it was all a mistake in the first place.”

When viewed the right-way-around, though, naming our current epoch the Anthropocene is a bit presumptuous and smacks of hubris. (Just to clarify an issue that one of the comments brought up, even if it was in an arrogant manner, I’m not suggesting that the researchers who favor the idea of the Anthropocene are trying to underpin our glory or importance. It appears that they are driven by ecological concerns for our increasing effects on global ecology and feel that present evidence justifies their position. Still, the idea that we should mark an epoch based upon quick, catastrophic changes our species has induced upon the planet does not seem justified given our present position temporally. Whether I’m right or wrong will only be known at a far off future date when I’ll likely be a fossil myself.) We have no idea what changes in ecology we may have already triggered, and there is something of a tacit acceptance of the idea that we’ll somehow make it through and be around to identify the root of the problem. We might not be; the future is contingent on factors that have already occurred and have yet to happen, so for now I think it’s best to leave the Anthropocene on the shelf until our species can take in the long view.

The news did remind me of a passage from Mantell’s Medals of Creation (which was copied from Lyell’s Principles of Geology), though;

“I passed one day by a very ancient and populous city, and I asked one of its inhabitants how long it had been founded? ‘It is, indeed, a mighty city,’ replied he; ‘we know not how long it has existed, and our ancestors were on this subject as ignorant as ourselves.’ Some centuries afterwards I passed by the same place, but I could not perceive the slightest vestige of the city; and I demanded of a peasant, who was gathering herbs upon its former site, how long it had been destroyed? ‘In sooth, a strange question,’ replied he, ‘the ground here has never been different from what you now behold it.’ ‘Was there not,’ said I, ‘of old a splendid city here?’ ‘Never,’ answered he, ‘so far as we know, and never did our fathers speak to us of any such.’

“On revisiting the spot, after the lapse of other centuries, I found the sea in the same place, and on its shores were a party of fishermen, of whom I asked how long the land had been covered by the waters? ‘Is this a question,’ said they, ‘for a man like you? this spot has always been what it is now.’

“I again returned ages afterwards, and the sea had disappeared. I inquired of a man who stood alone upon the ground, how long ago the change had taken place, and he gave me the same answer that I had received before.

“Lastly, on coming back again, after an equal lapse of time, I found there a flourishing city, more populous and more rich in buildings than the city I had seen the first time; and when I fain would have informed myself regarding its origin, the inhabitants answered me, ‘Its rise is lost in remote antiquity – we are ignorant how long it has existed, and our fathers were on this subject no wiser than ourselves.’”

Comments

  1. #1 Jim Thomerson
    January 29, 2008

    If we are indeed in the midst of making a notable mass extinction, then we can expect that the effects will go into deep time before biodiversity is restored. So, if we include the recovery time of several millions of years, maybe it will be noteworthy. Have you noticed that named segments of geologic time get smaller and smaller as we approach the present day?

  2. #2 someguy
    January 29, 2008

    OK, so maybe we can’t call it an “epoch” until we stick around for a while longer, but that doesn’t make the actual concerns any less valid. I think they’re just trying to be optimistic by assuming that humans will keep doing what we do for a long time to come.

  3. #3 Ian
    January 29, 2008

    The starting point of the Holocene is the end of the last ice age, 10,000 or so years ago. Although anthropogenic effects may one day be as measurable and significant as that, they are not currently, and certainly were not in 1800, when proponents of this plan want to mark the beginning of the Anthropocene. To me, there has to be a meaningful point or event to mark a boundary between geologic periods, epochs, etc. 1800 does not seem to qualify. We may decide to demarcate geologic time this way at some point in the future, but geologists of all people should be a bit more patient. It does seem a bit soft, even if I wholeheartedly agree with the motivation behind it. If we are going to take credit for an entire epoch, why not start earlier, with the rise of agriculture and the real roots of civilization?

  4. #4 SteveF
    January 29, 2008

    Another aspect to this debate is Bill Ruddiman’s recent work, arguing for significant human impacts on the atmosphere for much of the Holocene. It’s an interesting hypothesis, albeit still rather preliminary. The key paper (although he’s written a few now):

    Ruddiman, W.F. (2003) The anthropogenic greenhouse era began thousands of years ago. Climatic Change, 61, 261-293.

    The anthropogenic era is generally thought to have begun 150 to 200 years ago, when the industrial revolution began producing CO2 and CH4 at rates sufficient to alter their compositions in the atmosphere. A different hypothesis is posed here: anthropogenic emissions of these gases first altered atmospheric concentrations thousands of years ago. This hypothesis is based on three arguments. (1) Cyclic variations in CO2 and CH4 driven by Earth-orbital changes during the last 350,000 years predict decreases throughout the Holocene, but the CO2 trend began an anomalous increase 8000 years ago, and the CH4 trend did so 5000 years ago. (2) Published explanations for these mid- to late-Holocene gas increases based on natural forcing can be rejected based on paleoclimatic evidence. (3) A wide array of archeological, cultural, historical and geologic evidence points to viable explanations tied to anthropogenic changes resulting from early agriculture in Eurasia, including the start of forest clearance by 8000 years ago and of rice irrigation by 5000 years ago. In recent millennia, the estimated warming caused by these early gas emissions reached a global-mean value of similar to0.8degreesC and roughly 2degreesC at high latitudes, large enough to have stopped a glaciation of northeastern Canada predicted by two kinds of climatic models. CO2 oscillations of similar to 10 ppm in the last 1000 years are too large to be explained by external (solar-volcanic) forcing, but they can be explained by outbreaks of bubonic plague that caused historically documented farm abandonment in western Eurasia. Forest regrowth on abandoned farms sequestered enough carbon to account for the observed CO2 decreases. Plague-driven CO2 changes were also a significant causal factor in temperature changes during the Little Ice Age (1300 -1900 AD).

    I’m watching a Ruddiman – Maureen Raymo double bill in a few weeks time. Can’t wait!

  5. #5 Thomas R. Holtz, Jr.
    January 29, 2008

    Might as well add my 2 cents (even if it is a repeat from the Vertpaleo and Dinosaur mailing lists…):

    Yeah, I just trashed this in my graduate seminar today, along the following lines:

    1) If the function of the geochronology and chronostratigraphy is to correlate events (which it is), then we can already do so using newspapers etc. for the time frame considered…

    2) What they are describing (the effects of industrial human activity on the biosphere and chemosphere) has far more in common short term stratigraphic events (PETM; the Chicxulub impact & sequelae; environmental effects at the Permo-Triassic; etc.) than it does epochs.

  6. #6 Luna_the_cat
    January 30, 2008

    I would go with the “not an epoch, more a mass extinction boundary event” argument.

  7. #7 bettina
    January 30, 2008

    The designator “Anthropocene” may seem presumptuous or even hubris-laden to you. However, this line of response–indeed, the grand view of your argument–is fraught with intentional fallacy and fails to actually apply to what proponents of the term are saying.

    People who want to begin looking at the current period of time as overwhelmingly human-influenced are, largely, far from smug and proud. They say “Anthropocene” not because they trumpet human achievement–”Look at us, we cause mass extinctions and affect the climate on a scale not seen in millions of years!”–but because they are part of a gaining of awareness, of understanding just how serious our behavior is getting.

    Though we are starting to figure out the dire consequences of our actions, we are not disqualified from observing that the gravity of our effect on Earth is becoming ever more tremendous. In all likelihood, based on our scientific methods, we see that the Earth will take a while to recover–”a while” meaning, yes, geological time.

    So while you nitpick at whether it is appropriate for *humans* to expand *human nomenclature* (see sarcasm), the remainder of the cynical American anti-science crowd can point to you and say “I agree; and who are we, to presume we can have a large impact on the planet?”

    As an alternative, just pretend we called it the Neo-Carboniferous epoch, and the civilizations that discover our remains and what we did five ages from now can rename it the Anthropocene (in their own language) because, hello,
    “Anthropocene” is inherently more descriptive, hence precise. Who the heck cares? It doesn’t matter that you think something “smacks of hubris” invalidates the legitimate (and if you think not, then kindly provide scientific evidence to counter claims of mass extinction, extraordinary changes to ocean and climate, with hard data) idea of the Anthropocene. All that matters is that usually when someone accuses someone else (or, presuming to know too much, a whole group of people) of “hubris” it’s because hubris is present in the other party, the accuser, the one who dreams of hand-me-down glory, to achieve recognition for “taking down” a prominent idea.

    Same goes for that Thomas R. Holtz, Jr. guy who “trashed” this idea in his graduate seminar in a manner that allowed him to feel good about himself enough to proclaim publicly that he is in fact in a graduate seminar, what a smart chap he must be.

    In the end, the delineation of geological time-frames is not something that we can get “wrong”. If contemporary society deems it the Anthropocene, so shall it be, and if we revise it to or from any other name in the future, it’ll be because we decided something else was more suitable. Even in that scenario, no one would be looking back at you and thinking “man, that guy was right, he sure had the foresight to see that we were presumptuous”; they’ll still think you the witless wannabe who tried, with commentary like this, to bring other people’s novel ideas down, but who really didn’t have anything meaningful to contribute.

    Not that I do, either: this reply is even more vapid than your blog entry. Just a good faith effort to free you from feeling self-important.

  8. #8 bettina
    January 30, 2008

    Sorry, just wanted to clarify that I don’t think *you’re* cynical, American, and anti-science, even though it read that way.

  9. #9 Laelaps
    January 30, 2008

    You seem long on vitriol and name-calling and short on ideas bettina, your response to this post being little more than “Aw, gives these guys a break.” The point of the post is that geologists define geologic epochs and such naming requires a long view, a view that we don’t presently have (as I said in the post itself, the idea may well be revived and found useful, but we’re not there yet). Likewise, I used the term “smacks of hubris” rather than “hubris-driven” to denote what I feel is a certain leaning in the idea itself (the actual proponents might feel differently).

    You can take or leave what I say, but working geologists that have commented here and that I have linked to have brought up similar criticisms of the idea. It’s just too soon to tell, and whether it’s best to describe our impact in terms of an event or as an epoch remains to me seen. I’d be making the same argument if someone proposed the Neo-Carboniferous as well, so it’s not just about the moniker.

  10. #10 Greg Laden
    January 31, 2008

    The bottom line is that you can’t name a geological period that you are in, but you can name an extinction event that is utterly blatant, observable, and measurable.

  11. #11 bettina
    February 1, 2008

    Sorry for being so mean :P Was having a bad day and I lashed out intellectually (which should probably be in quotes).