Monday, May 27

Holocene or Anthropocene?

Could we please just give geologists their scale back? I’m asking nicely. I’m also adding my two cents to the debate as to whether the Holocene has given way to the Anthropocene. Now, don’t get me wrong, I get where it is that climatologists, anthropologists, and all those other ‘ologists’ promoting the use of the Anthropocene as a name for a clearly distinct epoch are coming from. I am also incredibly frustrated due to the number of people referring to the proposed Anthropocene as a period, or even an Era. In fact that is the part that bothers me the most because it reflects a basic ignorance of how the geologic scale is supposed to work… which is why I suspect there are so many people arguing on behalf of the Anthropocene in the first place. I also won’t deny that there are some valid arguments to be made on its behalf, it’s just that I don’t think that dividing geological periods into one week chunks is going to do anything but muck things up here.

But before we go any further, and to address one of my pet-peeves (that would be the people who insist on referring to the proposed Anthropocene as a Period, or even an Era) let’s get a few basic terms straight.

The world’s geological history is divided and subdivided into a series of periods (and I really shouldn’t use that term here, because one of those subdivisions is actually called the Period), which are clearly defined. At the top of that particular hierarchy we have the Eons. Luckily I am yet to find someone who refers to the Anthropocene as an eon, but maybe that’s just because the term is not nearly as familiar. There are four Eons (the Hadean, the Archean, the Proterozoic, and the Phanerozoic). The Archean, Proterozoic, and Phanerozoic (but not the Hadean), are further subdivided into a series of Eras. These follow a mostly straightforward naming pattern with the Eoarchean, the Paleoarchean, the Mesoarchean, the Neoarchean, the Paleoproterozoic, the Mesoproterozoic, the Neoproterozoic, the Paleozoic, the Mesozoic, and, just to mess with curious minds, the Cenozoic (in other words, still no Anthropocene here). I’m guessing you can figure out which Eras belong to which Eon on your own. Next in line come the periods. I won’t list them all, as their names are not as logical as those of the Eras, and frankly there are just way too many of them. Among the better known ones we have the Cambrian, the Permian, the Triassic, and the Jurassic. It is worth noting that there are no periods in the Archean, and that with the relative exception of the last two periods of the Neoproterozoic (the Cryogenian and the Ediacaran), the names of the Proterozoic periods are not commonly used, except for the most specialized literature. It is only in the Phanerozoic, when the emphasis shifts from geology to biology as multicellular organisms, along with their fossils, burst into the scene, that these names come into their own. It is also starting in the Phanerozoic that we see the Periods being broken down into Epochs. The Quaternary (that would be the current Period of the Cenozoic Era) is officially subdivided into the Pleistocene (starting roughly two and a half million years ago) and the Holocene (which begins at the end of the last Ice Age, roughly 11,600 years ago). Epochs are then further subdivided into Ages, but unless you work on a related field you are unlikely to find those in the wild. Anyway, it is at the Epoch level that the proposed Anthropocene would come into play.

Now, if your head isn’t spinning, let’s go back a couple of steps to the question of what to do with the Anthropocene in the first place. While the term keeps being tossed around, the fact remains that to this day none of the organizations that act as the gatekeepers of the scale has officially endorsed it, though they are seriously considering it. To me that is not necessarily an argument against the concept itself, but it does serve to complicate matters, as it means that we don’t even have a clear-cut definition of what we mean by Anthropocene in the first place. The concept was popularized back in 2000 by a Nobel Prize winning atmospheric chemist named Paul Crutzen, though he did not coin the term, and in a way it makes sense.

The changes undergone by our world since the advent of the Industrial Revolution are undeniable, they are easily measurable, and they are also unquestionably attributable to our species, the problem is that what we are talking about here is a period of at most a couple of centuries, and to me that falls into the realm of history, not geology, not to mention that humans have been having a noticeable impact on the biosphere since long before that. It is just that the change has become faster and far more noticeable in recent times. That is why others have proposed that the term be extended back by a few millennia, either to the beginning of the Agricultural Revolution, or even to the megafaunal extinctions at the end of the last Ice Age. That makes a little more sense, at least it would fit within the timescale we usually associate with geology… except for the fact that the end of the last Ice Age already marks the beginning of the Holocene. Which brings us to the proposal that, to my mind is the most sensible one of the lot: that the Holocene simply be renamed the Anthropocene, as that name is far more evocative, and easier to grasp. The problem is that the only thing that would require us to do is replace one word in a whole bunch of books, without changing one thing in the process, and that would reduce the whole charade to a serious case of much ado about nothing.

And then there is the obvious question, the one we are reluctant to ask: ‘does any of this really matter?’ and the truth is that I don’t know. We humans love to name and categorize things, but these are our categories. Nature does not particularly care, and while the fact that we are in the midst of an anthropogenic mass extinction is undeniable, whether it is termed a Holocene or an Anthropocene mass extinction would only matter if, when all was said and done, there were someone left to actually use those terms. The odds are not in our favor.

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