The assumption that humans are the single most significant cause of climate change is unsupported by the available science.
It is now quite popular in certain sets to describe our current age as the “Anthropocene.” This Age-of-Mankind label is credited (often by himself) to Paul Crutzen, who defines it as the “human dominance of the chemical, biological, and geological processes on Earth.”
The human dominance, lest there be any doubt. Depending on how exactly one wished to define it, this assertion might be arguable in some empirical sense, but the issue seems to be more about epistemics than empirics—calling it the “Anthropocene” does two things: first, it gratifies our aching human desire to believe in our own centrality. Second, it opens the lid to a Pandora’s box of political controls—a field where dominance has more than abstract relevance.
I have a copy of a Dutch map from 1660 showing the Sytema Mundi of Ptolemy juxtaposed with the Systema Secundum of Copernicus. The fact that this juxtaposition was even a thing, more than a century after Nicolas Copernicus published his heliocentric model, shows that letting go of humanity’s central, universal role was a big ask in the early modern period. I frankly doubt we are all that much more sophisticated today—the predilection for viewing ourselves as decisive agents of dominion is just too old a habit. Believing that humanity is the dominant factor in the “chemical, biological, and geological processes of the Earth” requires some rather grand assumptions about both ourselves and the nature of the planet we inhabit.
The question isn’t really whether or not we’ve altered our natural surroundings—all living organisms do, and to do so is part of the definition of life itself. The question is whether human impacts differ in kind or extent from other natural phenomena. Has this wise ape altered the chemical composition of the atmosphere? To be sure. Atmospheric nuclear testing alone has altered carbon-14 isotope ratios to an extent that the “bomb pulse” will be detectable far into the geological future. Has humanity altered the biosphere and its processes? Indubitably. Even a cursory glance at the history of global deforestation (and, perhaps more tellingly, afforestation) attests to this. Has mankind altered the geology of the terrestrial globe? Clearly—just look around you.
But the act of alteration is a far cry from “domination.” Would our self-aggrandized title hold if we applied the same standard to other species? Has the “lower” form of cyanobacteria altered the chemical composition of the atmosphere? Sure. As the great oxidation event demonstrated, the toxic off-gassing of trillions of organisms entirely altered the globe and shaped life as we know it. Iron-bearing bedrock turned blood-red, the newly oxygenated atmosphere allowed the first licking flame to ignite, catch, and sustain itself, and many argue it jumpstarted the prokaryotic/eukaryotic evolution. The move from essentially zero oxygen to around 210,000 ppm was a far more significant “domination” of chemical processes than humanity’s role in the move from 280 to 400 ppm of carbon dioxide. This immense chemical, biological, and geological change was brought about by the scum we try to flush out of our aquariums. Yet we do not call it the “Cyanobacterene”? Why not?
Perhaps because it is not politically convenient. The crises that plague our environmental sensibilities today tend, teleologically, to promote our own sense of centrality and to justify coercive top-down controls. Lost in the breathless rush to do something is a comparative perspective—our “unprecedented” impacts must be reined in by our governors, and quickly, there’s no time to lose. In addition to helping assuage our sense of yawning insignificance, assuming that humanity is the Earth’s prime-mover justifies a veritable constellation of state-mandates. Yet the evidence for our unequaled magnificence is slim: Sea level rise? The IPCC’s worst-case projections are dwarfed by the 400-foot rise since the last glacial maximum. Temperature change? The miniscule Azolla freshwater fern had a mightier influence, on the order of a 20 to 30-degree increase (compared to our modeled, “catastrophic” 1-3 degrees). Our vaunted “built footprint”? All of our cities, highways, dams, and constructions since Ur are pitiable compared to even one range of limestone hills created by calcium carbonate shell deposits (estimated to make up around 10% of the sedimentary crust). Our exploding population? As a species, we barely register on the biomass scale, not even cracking the 1% threshold.
You might argue this long-scale geologic perspective ignores the startling rapidity that humans, as a biological organism, have altered the globe. While not be trivialized, this fact too hardly grants us status as primary geo-agent. In just a few months, another Pinatubo-scale eruption would completely cancel out our projected century-long warming inputs. Some argue the Hiawatha asteroid impact triggered the Younger Dryas, the rapid cooling event in the late Pleistocene. Regolith ejecta from a 10 kilometer impactor could potentially do the same, on the order of just days. Despite these humiliating truths, words like “catastrophic,” and “irreversible” dominate the discourse about humanity’s impact on global ecosystems. It’s worth asking why.
The narrative of humanity’s dominance persists and grows. As one of my students put it on her final exam: “humanity has doomed the planet.” Yet are we really so very much different from other biological and geological agents of change? Is our transforming capacity really so unprecedented, so extraordinarily potent to warrant its own distinct geologic epoch? I don’t wish to sound like an all-is-well Pollyanna (it isn’t), but it doesn’t seem reasonable or even particularly helpful to use grandiosity to describe ourselves. In fact, to the extent that we need to tackle real environmental problems with cool-headed creativity, our self-absorbed rhetoric may actually hinder our efforts: in the frenetic push to present climate alarmism as a doomsday apocalypse, we may be giving up on the very forces of prosperity generation and technical prowess that can help us out of some of our self-generated pickles.
And this may be the relevant rub: calling it the “Anthropocene” is a powerful political instrument. If humans are the agente perniciosius, then the obvious conclusion is that we must mend our ways, conform to the proper order of things, and discard our wayward excesses. We are central and must therefore behave as such. Those touting the term Anthropocene waste little time establishing the list of penances: Crutzen recommends (“first and foremost”) we cease of eating “industrially produced meat” and changing from “private vehicles to public transport.” The list goes on, bending predictably toward an attack on capitalism itself and the liberty of individuals more generally in favor of sweeping coercive mandates.
We are at an odd moment of self-reflection for the species. Calling it the “Anthropocene” means we matter and lauding our “unparalleled” capacities for global change may help to re-center our place in the universe. Strange as it may seem, collective misanthropy may be in its way quietly comforting: we may have eaten from the fruit of the tree of knowledge but this proves we are at the center of Eden. The Copernican revolution was a cosmological reboot—not only was humanity pushed from the center of the physical solar system, but perhaps out of the center of the celestial universe as well. This discomfited not a few, as my Dutch map bears witness. Perhaps we never really got over it—perhaps we never really will.