Earlier this month, a team of scientists published a paper in Science providing supporting evidence that the Earth’s natural processes have been influenced by anthropogenic—human-made—factors, and thus, our planet is now in a geological epoch distinct from the Holocene epoch.
This paper, spearheaded by members of a working group on the Anthropocene, comes ahead of the International Commission on Stratigraphy’s decision this year about whether to formally name a new epoch called the Anthropocene, which denotes the moment when human activity first begins to influence rock strata (Earth’s layers on the crust). The International Commission on Stratigraphy, a scientific entity part of the International Union of Geological Sciences, describes its primary objective “to precisely define global units (systems, series, and stages) of the International Chronostratigraphic Chart that, in turn, are the basis for the units (periods, epochs, and age) of the International Geologic Time Scale; thus setting global standards for the fundamental scale for expressing the history of the Earth.” (For a primer on the geologic time scale, see here.)
The Anthropocene has been used informally in its current definition by researchers, scientists, and media since 2000 (the word itself has been used as early as the 1960s by Soviets), when Nobel Laureate in chemistry Paul Crutzen and biologist Eugene Stoermer wrote an argument (formalized into a paper in Nature in 2002) about the increasing role of human activity in transforming Earth’s landscape:
The escape into the atmosphere of NO [nitrogen oxide] from fossil fuel and biomass combustion likewise is larger than the natural inputs, giving rise to photochemical ozone (“smog” formation in extensive regions of the world. More than half of all accessible fresh water is used by mankind. Human activity has increased the species extinction rate by thousand to ten thousand fold in the tropical rain forests and several climatically important “greenhouse” gases have substantially increased in the atmosphere: CO2 [carbon dioxide] by more than 30 percent and CH4 [methane] by even more than 100 percent….Considering these and many other major and still growing impacts of human activities on earth and atmosphere, and at all, including global, scales, it seems to us more than appropriate to emphasize the central role of mankind in geology and ecology by proposing to use the term “Anthropocene” for the current geological epoch.
The formal adoption of the term Anthropocene is up for debate for a number of reasons. Some believe the term has been politicized (and pop-culturized) and that there is strong favor for the adoption of the term whether or not it makes sense. The working group defines the criteria for whether it should be accepted as a formal term or not by whether it is “(a) scientifically justified (i.e. the ‘geological signal’ currently being produced in strata now forming must be sufficiently large, clear, and distinctive) and (b) useful as a formal term to the scientific community.”
It’s also difficult to determine the scientific justification because there is disagreement about when the Anthropocene began and whether there is evidenced impact on the Earth that distinguishes this epoch from the Holocene. Though the working group suggests that the consensus is that the Anthropocene began in 1800 CE (the industrial revolution), a debate remains about whether the Anthropocene began when humans transitioned from hunting to mass-scale farming, when we first started testing atomic bombs (1960), the Industrial Age, or at different times and in different places. Some question whether it’s possible to define a unique point in time when the Anthropocene began or whether the Anthropocene began at “different times in different places because it represents a holistic concept that involves time, place, human cultural attainment and dominance, and a variety of environmental effects,” an argument put forth in 2015 by other researchers.
However, the most recent paper does not debate that there is a difference between the Anthropocene and the Holocene.Its abstract states that a series of “combined signals render the Anthropocene stratigraphically distinct from the Holocene and earlier epochs,” with the combined signals being (1) “the appearance of manufactured materials in sediments, including aluminum, plastics, and concrete,” (2) the fundamental change in carbon, nitrogen, and phosphorus cycles, (3) the “rates of sea-level rise and the extent of human perturbation of the climate system” which “exceed Late Holocene changes,” and (4) species invasions and accelerating rates of extinction.
Despite the uncertainty of this term, the reality is that humans are profoundly changing the environment for the worse. Chair of the working group and a lead on the Science paper Jan Zalasiewicz graphically describes the magnitude of plastic we produce every year in a press release: “We now make almost a billion tons of the stuff every three years….If all the plastic made in the last few decades was clingfilm, there would be enough to put a layer around the whole Earth. With current trends of production, there will be equivalent of several more such layers by mid-century.”
Even more worrisome is the amount of cosmetic microplastic waste in the ocean and the effect of plastic on ocean ecosystems and its long-term ecological effects. “Once buried, being so hard-wearing, plastics have a good change to be fossilized—and leave a signal of the ultimate convenience material for many million years into the future….The age of plastic may really last for ages,” Zalasiewicz added.
As compelling as this semantics debate is, what’s more important is that this evidence drives us to action. Some scientists like James Scourse, professor of marine geology at Bangor University and director of the Climate Change Consortium of Wales, implore the public and fellow scientists to lower priority of this debate and shift their focus to solutions: “And while the anthropocenists rearrange the deck chairs, other scientists are getting on with the business of trying to understand, and do something, about the crisis we face.”