Human Systems and Earth Systems Are One

by Julia Adeney Thomas

Rat snakes have died from eating their own tails. Suicide by self-devouring may seem preposterous, something no creature would do, but it happens, and not only with rat snakes. Our species too seems hell-bent on destroying ourselves and taking much of the web of life with us. Since the mid-twentieth century, we have been devouring at ever increasing rates the biogeochemical Earth System of which we are now the dominant part. With each passing year, our jaws close closer to our skulls. The annual cycle of overconsumption, like the circle of the snake, tightens. Last year, by July 28, human beings had consumed all that Earth could replenish biologically in 2022. As the month of August unfurled in a hum of vacations in the northern hemisphere and the gradual warming of spring in southern half of the globe, we started going over-budget, consuming the sustenance of future years. Global human consumption of Earth's biocapacity topped out at 1.75 planets worth by December 2022.

"Earth Overshoot Day,” as it's called, has generally come earlier every year since 1971 when the eponymous organization started calculating dates. In 1971, we fell just short of making it to New Years, hitting Earth Overshoot Day on Christmas. Since then, things have mostly gotten worse. The Covid pandemic caused a momentary hiccup in the hunger, but our voraciousness has now returned. Earth Overshoot Day "is computed by dividing the planet’s biocapacity (the amount of ecological resources Earth is able to generate that year), by humanity’s Ecological Footprint (humanity’s demand for that year), and multiplying by 365, the number of days in a year."1 This gives us a global average, but of course the consumption rate is unequal across the globe. America feasts at the rate of approximately four Earths’ worth per year, and by March 13, 2023, we hit our Earth Overshoot Day for this year. Qatari citizens (minus the guest workers straining in the heat of construction sites and kitchens) are even more insatiable. Their style of life if maintained everywhere would require about six Earths, and in 2023 they crossed the line on February 10.

The idea of a self-devouring serpent, known as an ouroboros, popped up independently in many places from ancient China to ancient Egypt and South America. In those earlier millennia, it's unlikely that the ouroboros was a premonition of our current conundrum; it seems instead to have suggested infinity. But infinity is precisely not what it suggests today. In fact, the ouroboros is a pretty accurate symbol of the Anthropocene as discussed by Jan Zalasiewicz et al in this issue.

Ouroboros - The snake that eats it’s own tail

Drawing by Birgitta Jansen


The Anthropocene ouroboros is us and our planet, the planet we now dominate and overwhelm: in other words, the human-and-nature system driving towards self-destruction. Since our activities are an integral part of the Earth System, it's important not to think of ourselves as a snake in a larger landscape over-using some of its bounty. To frame the challenge that way focuses our minds on single resources such as fossil fuels, and allows people to speak of "climate change" separately from the land-use crisis, the population crisis, the water crisis, the democracy crisis, the biodiversity crisis, growing inequality, and other dangers. More accurately, the Anthropocene framework presents human systems and Earth System as inseparable; when we use any of our resources, we're now munching on ourselves. We literally eat and breathe our plastics and meet ourselves coming over the horizon as megacities meld. We move so much soil and rock that the "Anthropocene sediment load" as geologists call it "exceeds 300 billion tons (Gt) per year," a mass flux that includes only a very "small (<6%) contribution from natural processes."2 Human-made things (anthropogenic mass) exceed the mass of all living things.3 Our "domesticated mammals now outweigh wild land mammals 30 to 1."4 Were we to crowd all people together and weigh ourselves on a giant scale, our clawless, furless, thin-skinned species would decisively exceed the poundage of all wild creatures from elephants to mice combined.

How do we transform this self-devouring Anthropocene ouroboros back into something like the ancient symbol of infinity that it once was? How do we reverse the snake's voracious frenzy, and get it to release its hold, expanding into a more ample "o"? Researchers propose many avenues, but here I will speak of the three "r"s: reduce, recycle, relax.


According to scientists, the Anthropocene is caused not by one factor, but by the systemic, interacting factors of "overpopulation, overproduction, and overconsumption."5 Our overshoot means that overall growth in human demands is no longer possible. Growth in one sector will mean degrowth in another. Many people misunderstand this issue. Take energy. In many quarters energy is framed as a siloed problem of moving away from fossil fuels. Change the energy source to something such as nuclear reactors or lithium batteries, and the problem will be solved, after which growth can continue. French President Emmanuel Macron exemplifies this attitude with his recent claim that "climate adaptation is also a growth agenda."6 Rarely is there any mention that this increase in energy will be used for further altering of Earth's crust, moving mountains, digging ports, tunnels, and mines, more destruction of biodiversity, building more transport to provide ever more goods for more people, powering ever greater demands on our time and attention. More energy, less of everything else. With this "green solution," the snake just goes on masticating itself, focusing on another of its internal organs. Relying on lithium batteries, for example, would greatly exacerbate the fresh water shortage. The real question is how to reduce the amount of energy we use.

In the past seventy years, our overall energy use has been shockingly high, higher than in the preceding 12 millennia combined. To be exact, "human energy expenditure in the Anthropocene, ∼22 zetajoules (ZJ), exceeds that of the prior 11,700 years of the Holocene (∼14.6 ZJ) . . . ."7 Policies need to keep the goal of less energy use in mind: more walking; fewer cars; local food; less travel; fewer people; less consumption; tighter communities. American historian Mike Davis's advocacy of dense, livable urban areas is one place to find hope. Carlos Moreno's "15 Minute City" concept underscores planning that puts work, schools, grocery stores, doctors, libraries, and shops all within an easy walk or bike ride. Actual cities such as Tokyo already do this; Paris is well on its way; Seattle is trying.


To say that human beings need water, and lots of it, is surely an uncontroversial statement. Within three days, dehydration can lead to organ failure and death. Already about 10 percent of people struggle to find enough to drink. According to the United Nations, by 2050 "five billion people, or around two-thirds of the world's population, will face at least one month of water shortages."8 And yet, we’re extravagant with this resource, the very basis of life. Fresh water regenerates naturally at the rate of less than one-hundredth of 1% per year, but we're drawing down water much more quickly, sucking up underground reservoirs for farms and cities as well as depleting above ground supplies.9 We're even polluting some water to the point where it can never be returned to a potable condition by the sun-powered hydrological cycle. Finally, the water we draw from rivers, lakes, and glacial melt for our own use is no longer available for the rest of the aqua-loving web of life.
Thankfully a great deal of water can be recycled artificially by directing it from our sinks, toilets, and gutters back through municipal treatment plants. Singapore is doing this already, "taking the 'waste' out of its wastewater and turning sewage into safe, clean drinking water using an advanced filtration and treatment system."10 This small nation is committed to self-sufficiency in this vital resource to free itself from dependency on neighboring Malaysia. An essential part of its campaign is actively educating citizens on the safety of this microfiltered water. Some American cities are following suit. Fairfax Virginia is taking tentative steps, reusing water for lawns, commercial car washing businesses, and in construction. Other places such as Fountain City in southern California have embraced the full challenge, producing potable water. After all, in the long view, all the water we drink is recycled waste water.


What drives our massive overshoot? What, at root, spurs our self-devouring? Usually we answer in terms of technology, energy use, and the like. While that's true, there's a deeper cause, one more within the realm of social norms than science: the speed of contemporary life. Thomas Hylland Erikson's brilliant study Overheating: An Anthropology of Accelerated Change catalogs the ever faster destruction caused by ever faster modes of life, consuming ever greater resources. Flying, for instance, not only requires more fuel, but aviation emissions released at high altitudes cause more damage than those at ground-level. As a recent article reports, "Aircraft also release nitrogen oxides, oxidized sulphur, water vapor and contrail cirrus – artificial clouds produced when water vapor condenses around soot from the plane’s exhaust at high altitude. This temporarily increases the amount of heat that is trapped in the atmosphere."11 And that's not all. Plastic waste to the tune of six million tons annually is a by-product of passenger flights. $4 billion worth of wasted food is also added to that toll from untouched airline meals.12 Do we really need such tearing haste? In the final instance, the choice is not a matter for individuals to decide but a question of changing social norms.
We simply can't reduce and recycle at high speed. Nor at that pace can we cement the community ties that give us greater resilience. Sociologist Juliet Schor argues for a four-day work week for civic and environmental reasons.13 Political scientist Daniel Aldrich has shown that the Japanese communities that best survived the Fukushima tsunami in 2011 were those where time had been invested in neighborliness for years. In tight-knit communities, people aided each other as the wave (130 feet at its highest point) approached land, even though official instructions warned them to look to their own safety first. Furthermore, the recent spate of happiness studies demonstrate a negative correlation between life in the fast lane and contentment. By slowing down, we not only relax the serpent's bite on our physical well-being but generate safety and satisfaction.


As we confront the Anthropocene, "reduce," "recycle," and "relax" are just a few of the many useful "re" words. "Repair," "regenerate," "renew," and "reflect" might also be added to the list. As this prefix indicates, the crisis we face is non-linear. Thinking of our Human-Earth System as a single integrated cyclical whole can be helpful. Our choice is this: either we continue tightening the self-devouring circle of overpopulation, overproduction, and overconsumption, or we relax our grip and turn the Anthropocene ouroboros back into the symbol of more bounteous (though never infinite) possibilities.

Julia Thomas grew up in the coal country of southwest Virginia. Her sharp interest in environmental questions comes from her love of those mountains. Completed graduate work at the University of Chicago and is currently Associate Professor in the history department at Notre Dame University. Among her most recent published books is Altered Earth: Getting the Anthropocene Right (Cambridge University Press, 2022)


2) Syvitski, J., Ángel, J.R., Saito, Y. et al. Earth’s sediment cycle during the Anthropocene. Nat Rev Earth Environ 3, 179–196 (2022).
3) E. Elhacham, L. Ben-Uri, J. Grozovski, Y. M. Bar-On, R. Milo, "Global human-made mass exceeds all living biomass," Nature 588, 442–444 (2020).
4) Lior Greenspoon, et al., "The global biomass of wild mammals," PNAS (2023) Vol. 120, No. 10, e2204892120,
5) Syvitski, J., Ángel, J.R., Saito, Y. et al. Earth’s sediment cycle during the Anthropocene. Nat Rev Earth Environ 3, 179–196 (2022).
6) Emmanuel Macron, Macky Sall, and Mark Rutte, "The climate is already collapsing in Africa – but its nations have a plan," The Guardian, Friday November 4, 2022.
7) Jaia Syvitski, Colin N. Waters, John Day, et al. "Extraordinary human energy consumption and resultant geological impacts beginning around 1950 CE initiated the proposed Anthropocene Epoch," Communications: Earth and Environment 1, 32 (2020).
8) Daniel Cusick, "5 Billion People Will Face Water Shortages by 2050, U.N. Says, " Scientific American (November 30, 2022)
9) Sandra Postel, " Sustaining Fresh Water and Its Dependents," in The Worldwatch Institute, Is Sustainability Still Possible? State of the World 2013 (Washington, Covelo, London: Island Press, 2013), 52.
10) Johnny Woods, "Singapore has a model for turning sewage into safe drinking water," The Print (4 December 2022)

Singapore has a model for turning sewage into safe drinking water

11) Christopher de Bellaigue, "Will Flying Ever be Green?" The Guardian (April 6, 2023)
13) Juliet Schor, "The Case for a 4-Day Work Week," Ted Talks