Welcome to the Anthropocene: Humankind's layer on the Earth
Sunday, February 27, 2011 at 08:29PM 
TokyoWelcome to the Anthropocene. Man’s impact on the planet is now believed to be so great geologist are considering creating a new geological epoch. What factors are driving such a substantial impact on the planet? What will cause the geological record to mark our presence? If we are in the Anthropocene, when did it begin?
According to Elizabeth Kolbert writing in the March issue of National Geographic, Paul Crutzen coined the term “anthropocene” while attending a scientific conference. When the chairman kept using the term Holocene to describe the current epoch, Crutzen exclaimed “'Let's stop it, we are no longer in the Holocene. We are in the Anthropocene.' Well, it was quiet in the room for a while." That quiet has since led to a lot of thinking and scientists now considering the possibility that a new geological epoch has begun.
Stratigraphers are geologists that study the Earth's strata, the layers you can see at a roadside cut. Kolbert observes:
Stratigraphers … take the long view—the extremely long view—of events, only the most violent of which are likely to leave behind clear, lasting signals. It's those events that mark the crucial episodes in the planet's 4.5-billion-year story, the turning points that divide it into comprehensible chapters.
So it's disconcerting to learn that many stratigraphers have come to believe that we are such an event—that human beings have so altered the planet in just the past century or two that we've ushered in a new epoch: the Anthropocene. The record of our impact leaving “may look as sudden and profound as that of an asteroid”
If we are depositing Earth’s latest layer, what will the layer consist of when studied in the future? A number of possibilities have been suggested:
- Cities - Not likely. These may only leave “transient” marks on the geological record.
- Farming - Agriculture now covers about “38 percent of the planet's ice-free land.” However, its impact may be hard to detect and is more likely to come “from the pollen record—from the monochrome stretches of corn, wheat, and soy pollen that will have replaced the varied record left behind by rain forests or prairies.”
- “Massive” soil erosion - May be hard to detect since dams “are holding back sediment that would otherwise be washed to sea.”
- Destruction of forests - “Loss of forest habitat is a major cause of extinctions, which are now happening at a rate hundreds or even thousands of times higher than during most of the past half billion years.”
- Alteration of the atmosphere - Kolbert notes that alteration in the composition of the atmosphere is “probably the most significant change, from a geologic perspective” and “could push global temperatures to levels that have not been seen for millions of years.” "The consequences of burning billions of tons' worth of coal and oil are likely to be clearly discernible." As our oceans are acidified, coral reefs will disappear. This “reef gap” will be visible as are the ones that “marked each of the past five major mass extinctions.”
When did the proposed Anthropocene begin? Was it during the agricultural revolution when Homo sapiens began to increase the CO2 content of the atmosphere? Or, during the late 18th century when “carbon dioxide levels began what has since proved to be an uninterrupted rise.” Or, in “the middle of the 20th century, when the rates of both population growth and consumption accelerated rapidly.” Kolbert also notes:
Some scientists argue that we've not yet reached the start of the Anthropocene—not because we haven't had a dramatic impact on the planet, but because the next several decades are likely to prove even more stratigraphically significant than the past few centuries.
Over the next few years, the International Commission on Stratigraphy (ICS) will be debating whether to officially name our current epoch the Anthropocene, and if so, when it began. Whether it started 10,000 years ago, or is just about to start, humankind is changing the planet dramatically and in a short geological timeframe. Future geologists will see our mark in those stripes of stone we see in roadside cuts or in the mountains as we travel our fair planet.
Source: Enter the Anthropocene—Age of Man. Elizabeth Kolbert, National Geographic, March 2011.
Reader Comments (2)
Paved roads. If we disappeared today, our roads would still be detectable millions of years from now.
A few thoughts on what would mark the anthropocene: What individual objects would indicate past intelligent life on a barren earth, found in a sedimentary layer? Faceted diamonds, both natural and industrial. High tech ceramic artifacts, such as tooling. Stainless steel objects, perhaps. Fossilized skeletal remains, arranged in vast, orderly arrays. Fossils indicating advanced surgical repair and use of artificial components, and indications that individuals far outlived massive skeletal damage rendering them invalid. Bones showing extreme damage capable of being caused only by high velocities or high energies (gunshot, explosions, crashes).
Where would a visiting alien scientist look (and with what technologies)? The vast sedimentary buildup in the artificial lake above China's Three Gorges Dam, seeded with centuries of human artifacts and abandoned villages, perhaps including gold and silver jewelry or coins. Would they recognize the fracking (?) of shale formations as an artificial phenomenon, or discover such durable evidence carved into solid rock itself, such as mineshafts, oil wells, quarries, and fortifications (also capable of protecting skeletons and durable artifacts).
To what extent do the world's oceans already protectively cover the most durable components of naval and air weaponry, such as the propulsion components of sunken nuclear submarines? Or the nuclear waste buried at sea in the 1950's. Does enough of the Chernobyl footprint remain to indicate nuclear energy production; are nuclear waste disposal sites discovered that show intentionally shaped materials? Did the atmospheric testing of nuclear weapons create an ineradicable global trace layer revealing (some of) the activities of man? Will the alien scientist's suspicions be confirmed by excavation of underground nuclear bomb test sites?
I think its safe to say we've abundantly seeded the ground for far future stratigraphers, with the alteration of and manufacture of geologically durable materials. Something as common as the diamond of a wedding ring will survive intact, yet a single discovery will indicate intelligent, tool-using life. Other indicators will, I believe, be rightly linked to these indicators of industrialization, now of global scale and presence, including mass erosion based on mass agriculture, and possibly land subsidence from petroleum extraction and vast projects like 3 Gorges.
Clearly, our activity on earth is something qualitatively new. We are disrupting and altering natural geological structures that have remained intact for hundreds of millions of years. We don't find signs of eons past excavations of the sort we perform; there are no tunnels and well boreholes through 250 million year old rock other than those we have made; the fossil record shows no indication of medical repairs until the emergence of man, or of the creation of durable, intelligently designed materials until very recently.
Final thought: Past epoch marking events have been catastrophic. This one may prove different, simply because it reflects the emergence of directed large-scale intelligent activity. Our progress is driven by specialization on the intellectual plane within the species, not the specialization through speciation such as that of dinosaurs. Our technological prowess is growing in all technological and scientific disciplines (and across disciplines), pointing to near-future transformational technologies that have the potential to enable continued rapid improvement to the quality of life. (I'm thinking of highly distributed, ultra-efficient, low-cost solar energy, for example). It's necessary to remind oneself how different and improved life is (in advanced societies) compared to 150 or 200 years ago. If unimpeded, and if supported by economic prosperity, what great improvements are possible not just for advanced societies but all of mankind? So let me leave you with a question: what would a geological strata marking mankind's success look like?