The task of researching, categorizing, and documenting the unfathomably ancient Earth’s timeline belongs to stratigraphers – scientists who study the features of rock strata to learn our planet’s geological history. Stratigraphy might sound like an insulated, esoteric pursuit; dividing Cambrian time into new sections isn’t something that affects the average Joe.
At least that was the case until a team of stratigraphers from across the globe garnered recent news coverage over a proposed change to the Geological Time Scale. The group made a proposition to the International Geological Congress in Cape Town late this summer: according to their research, the Earth has entered a new epoch, called the Anthropocene.
While potentially changing the Geological Time Scale certainly rattles the stratigraphy world, the action’s ripples reach beyond even science observers. It’s an intellectual distinction that can be used as a signal of just how dire our current situation is. In fact, it could be argued that the greatest effect of proposing the Anthropocene is that it serves as a wakeup call for the root cause of the shift: the humans.
Anthropocene Research Origins
The Anthropocene is not yet formally defined as a unit within the Geological Time Scale, but the scientists have been hard at work to evaluate its accuracy and necessity for over a decade. Its origin story is rife with the drama only scientists can produce. The Dutch Nobel prize-winning atmospheric chemist Paul Crutzen was attending a conference in Mexico City in 1999, and was eventually fed up with the conference chairman referring to the “Holocene” as Earth’s present moment. Crutzen allegedly blurted, “’Let’s stop it. ‘We are no longer in the Holocene. We are in the Anthropocene.” The other scientists were quiet, but many were also in agreement. Crutzen co-authored a paper in 2000 formally proposing the term, and “Anthropocene” has since gained steam and scientific followers.
The working group that has researched the Anthropocene question since 2009 (the same that defended its addition to the time scale in Cape Town) defines the Anthropocene as “the present time interval, in which many geologically significant conditions and processes are profoundly altered by human activities.” The evidence for the cataclysmic shift is found in changes in soil, oceans, and the atmosphere—ranging from elevated levels of nitrogen to “dead zones” both on land and in the sea. Such enormous shifts are caused by the human-driven forces of colonization, agriculture, urbanization, and global warming, marking the first time that humans have had such an enormous effect on all aspects of our world.
Understanding Our Epoch
For those who are not geology buffs, the Geological Time Scale is a long timeline broken into large chunks of time with more specific subcategories. Two eons are split into eras. Eras contain periods, which are further broken into epochs, which are further refined as ages. We are currently in the second period of the Cenozoic Era, known as the Quaternary Period.
In the scale of the 4.6 billion-year history of the Earth, our period is small; it began only 2.6 million years ago. The period has been dominated by a series of ice ages, which have caused rapid changes in sea levels and in surviving flora and fauna. So far, there have been two epochs in the Quaternary Period, the Pleistocene and the Holocene Epoch. The Holocene Epoch began about 12,000 years ago, at the end of the last Ice Age. The resulting stable climate fostered the rise of human civilization – at least that is until modern human activity vastly altered the climate with the rise of carbon dioxide emissions.
If the current proposal to include the Anthropocene is accepted, it will date the end of the Holocene and rise of the Anthropocene as occurring in roughly 1950 CE. The radioactive material that entered the soil record thanks to atomic testing in the 1950s and ‘60s is the most widely cited evidence for why a new epoch is needed, but the astonishing increases in carbon dioxide emissions, plastic pollution, deforestation, and nitrogen from artificial fertilizers were other factors the scientists mentioned.
Scientific Debate
Some scientists say that the recent start date creates too short of window for an epoch; after all, epochs typically span millions of years. They suggest that the Anthropocene could be classified as an age within the Holocene epoch rather than as an epoch in its own right. Dr. Jan Zalasiewicz, the chair of the working group, counters with this retort: “One criticism of the Anthropocene as geology is that it is very short. Our response is that many of the changes are irreversible.”
The working group’s 35 members have voted 34 in favor (with one abstention) of the claim that Anthropocene is stratigraphically real. The vast majority of the group members said the hierarchical level should be formalized as an epoch, and identified about 1950 CE as its start date. Due to plutonium fallout
To be approved beyond the group, the members say the term needs to be useful, and needs to be scientifically justified, requiring that the evidence be “sufficiently large, clear and distinctive.” The scientists must now spend time deciding which evidence is the strongest for their case. Specifically, they must decide on a location that demonstrates the division of a new epoch (the Holocene, for example, is shown in the boundary between two layers of ice layers from a core from Greenland), and then submit the to the stratigraphic authorities for review.
Quick Adoption for Rapid Change
Depending on how quickly the working group can collect its evidence and construct an argument, the International Commission on Stratigraphy might be able to ratify the working group’s Anthropocene distinction in as little as three years. That speed is virtually unprecedented in the world of Stratigraphy, where such decisions have previously taken decades, if not centuries, to be finalized. Yet, the breakneck pace is fitting for the rapid change that stratigraphers are trying to capture. Our human understanding of the world must adapt synchronously with the human-driven changes our Earth experiences – and right now that demands an exceptional pace for exceptional change. The quicker we have the terminology to process just how severe our actions are, the sooner we can ameliorate the damage we inflict upon our planet.
If humans are forced to grapple with the idea that we have altered the Earth to such a radical degree as a new epoch, perhaps we will hold ourselves accountable and take necessary actions to heal the harm we have inflicted. Radioactive material can’t be sifted out of the soil, and already-burned fossil fuels can’t be taken back, but our habits regarding plastic and deforestation can certainly be altered to be more sustainable. Our human-made particles may have already settled into the geological record, but it’s up to us how long the Anthropocene will continue, and what shape it will take. Ultimately, we decide how deep the scar we leave in the geological record will be, and our lifestyle choices will dictate whether or not stratigraphers will be around to measure it.
Featured photo by Edwin van Buuringen
