Updated: Jul 16
Keywords: Sustainability; Paleontology; Climate; Carrying Capacity; Overpopulation
“The deeper I go into myself the more I realize that I am my own enemy.” ― Floriano Martins
As the groundwork is laid for the inception of my PhD dissertation, one cannot help but be overwhelmed with questions, wrestle with apprehension and be swamped with uncertainty, as the ensuing 4 years will be dictated by what sort of hypothesis and abstractions are flowing through this doctorate candidate’s mind at this point in time. As my interests converge around the impending viability of not just our civilizational apparatus but also of our existence and interaction with the Earth and its non-humans passengers, I am drawn to ponder on the most straightforward problem of all, the one holding it all together:
The Nature of Life
Scientists can’t determine the exact point in time when life ‘appeared’ (the term is debatable in itself. Did the first lifeform arise? Evolve?), however, the oldest known fossils of the earliest lifeforms have been dated to have formed between 4.2 and 3.8 billion years ago (Dodd et al, 2017; Mojzsis et al, 1996). Regardless of the exact date, it is accepted that by 3.5 billion years ago, life was already widespread and advanced enough to appear more frequently in the fossil record (Altermann & Kazmierczak, 2003).
A few billion years later and innumerable humans more, Homo sapiens felt the need to conceive of a term that would capture the vast and gargantuan testimony of deterioration that the natural world was facing. The most prescient individual of this species to produce such a concept was Hans Carl von Carlowitz, who saw that natural resources (specifically forests) needed to be mindfully harvested so that the supply wouldn’t be exhausted (World Ocean Review, 2019). Von Carlowitz named it ‘sustainability’ (von Carlowitz, 1713).
Lamentably, the term has up to the present time, been subject to profound metamorphoses as well as been hijacked to suit different narratives and intentions. The modern pervasive application of the concept sustainability has meant that its core meaning has become ambiguous and unintelligible (World Ocean Review, 2019).
Nevertheless, the crux of sustainability remains unchanged, and I would offer a better description here than the one intoned by the devotees of ‘sustainable development,’ known as the “development that meets the needs of the present without compromising the ability of future generations to meet their own needs” (Basiago, 1995). It would sound something like: the state in which the inherent environmental degradation caused by one or more lifeforms of a single species or a multitude, isolated or interacting with each other end up outstripping the natural regeneration capabilities of a given segment of the biosphere, leading to a loss of resilience, and eventually, collapse.
In effect, this proposed definition of sustainability is similar to that of carrying capacity, offered by the American sociologist William R. Catton Jr in his book Overshoot: The ecological Basis for Revolutionary Change (1982) and eloquently re-stated in the book Life on the Brink: Environmentalists Confront Overpopulation (2012), where Catton affirmed:
“Carrying capacity limits, too often unrecognized, mean that in any environment there is a rate or amount of resource use that cannot be exceeded without reducing the subsequent ability of that environment to sustain such use.”
As a result, carrying capacity can be surmised as the means of a population of a given species, on a specific environment, to be supported indefinitely, which is to say, without causing habitat deterioration that would dwindle that environment’s future life-supporting capacity. Correspondingly, we could even assert that such a population might or might not be in a sustainable state relative to its environment, thus rendering the term utterly dependent on the characteristics and activities of the beings sheltered by given environ.
Consequently, the question that has been building up until now is the following:
Can life ever be sustainable?
At first glance, the question appears to be at variance with itself. How could life notbe sustainable, one might ask? Could sustainability even make sense without life? Can we describe an extra-terrestrial planet or other celestial body without traces of life as being in a sustainable state?
If we were to consider Life through the lens of what James E. Lovelock (1972) coined as the Gaia hypothesis, then we would recognize life (as a combination of the interaction of both living organisms and inorganic elements, that is to say, biota influencing aspects of the abiotic world) as a self-regulating and complex system that has the ultimate goal of perpetuating itself, therefore requiring the sustainability of the entire structure to be maintained, so as not to risk turmoil which might jeopardize its continuance (Lovelock, 2010). Equally important, as posited by the Gaia hypothesis there’s another concept that is analogous to sustainability, and that is the existence of a planetary homeostasis, which seeks to keep optimal conditions for life and is maintained by a sort of ecological competition (Watson & Lovelock, 1983), leading to the self-regulation of processes such as global surface temperature, oceanic salinity, concentration of oxygen in the atmosphere or the processing of CO2.
Despite this seeming state of equilibrium, one glance at the paleo climatic record is enough to undermine the notion that life always has its best interest in mind. Surely, the history of the planet provides us with enough antithetical examples in which life wasn’t in a state of sustainability while spiralling out of control, thus, profoundly changing the habitability of the Earth. Markedly, one major cataclysmic events jump to mind. The Great Oxidation Event (GOE) (Bekker, 2014) was likely the most serious extinction episode occurring on Earth, even more catastrophic than the ‘Great Dying’ (Dorado et al. 2010).
The GOE takes us back a few hundreds of millions of years after life had started to swell and stretch throughout the planet, to about 2.4 billion years ago, during the Paleoproterozoic Era (Margulis & Sagan, 1997; Lyons, Reinhard & Planavsky, 2014). At that time, the Earth was mainly populated by anaerobic bacteria thriving on the ocean (Plait, 2014).
Enter the cyanobacteria (commonly known as blue-green algae). These beings were wildly proliferating due to a dual process of evolution by natural selection which benefited them immensely (Marshall, 2015). In effect, these beings evolved multicellularity (Schirrmeister, de Vos, Antonelli & Bagheri, 2013; Schirrmeister, Gugger & Donoghue, 2015) and through photosynthesis, spearheaded a cutting-edge process for the production of energy, while spewing oxygen as a by-product (Marshall, 2015). As a result, the atmosphere started to accumulate oxygen, and even though at first, the natural sinks could keep up with the production (e.g. by being bonded with iron), eventually they became saturated and the anaerobic bacteria started to perish before this unfamiliar and toxic molecule (Plait, 2014), but it doesn’t stop there.
As the cyanobacteria filled up the atmosphere with oxygen, the reactive molecule started to respond to methane, converting it to carbon dioxide. As methane is a more powerful greenhouse gas than CO2, the Earth started to cool. Its consequence was another tumultuous period that still perplexes scientists today. The “Oxygen Overshoot” had started an anaerobic carnage and then unleashed profound glaciations, setting up positive feedback loops (Caldeira & Kasting, 1992), producing ice even in the low-latitude tropical regions, creating the so-called ‘Paleoproterozoic Snowball Earth’ (Kopp, Kirschvink, Hilburn & Nash, 2005; Kirchvink et al. 2000).
For curiosity sake, the Earth was able to break-free from its frigid state due a combination of effects, with the most significant being the same that is disrupting the climate today, the accumulation of CO2in the atmosphere. The main difference to this period more than 2 billion years ago, was that the ocean-atmosphere interaction was mostly severed due to the layer of ice covering an extensive area of the planet. Since atmospheric CO2 and methane (mainly emitted by volcanoes and microbes converting organic matter under the ice into gas) couldn’t be absorbed, these created a powerful greenhouse effect. Eventually (4 to 30 million years) the ice melted, initiating once again a positive feedback (ice-free land has reduced albedo, which absorbs more energy from the Sun) that warmed the Earth (Crowley, Hyde & Peltier, 2001; Pierrehumbert, 2004).
The last stage initiated by the Great Oxidation Event, and possibly the one that most profoundly changed life on the planet and Earth’s history, was an unlikely episode in which the abundant levels of oxygen (which had confined anaerobic bacteria to the deepness of the oceans, and produced abounding lifeforms dependent on the molecule), suddenly (in a geological time anyway) plummeted and exterminated almost all life on the planet (Hodgkiss, Crockford, Peng, Wing & Horner, 2019). This scenario of “feast” to “famine” of oxygen lasted for almost 1 billion years, a lethargic rebound effect unlike any other mass extinction, which thoroughly transformed the make-up of life on Earth (Dapcevich, 2019), as well as its geomorphology (Gross, 2015).
Surprisingly, what makes the Great Oxidation Event so noteworthy even among all the ensuing Mass Extinctions is that its cause was entirely biological (Lyons et al. 2014). There was no interference from celestial bodies crashing into the planet, as was the case with the Cretaceous-Tertiary (K-T) Mass Extinction ~65.5 million years ago with the infamous asteroid that triggered the extinction of the dinosaurs (Schulte et al. 2010). In like manner, there was also no massive ejection of volcanic matter as it appears to be the cause of the end-Triassic mass extinction, roughly 201.4 million years ago (Ruhl et al. 2011), or even a combination of the two, as well as the sudden release of methane hydrate and/or carbon dioxide, which unleashed the Permian-Triassic extinction (aka ‘Great Dying’) around 252.28 million years ago (Shen et al. 2011), wiping out almost as 95% of all species on Earth (Benton & Twichett, 2003).
Ultimately, due to its biological origin, the Great Oxidation Event - and its cascading effects - becomes a suitable candidate to argue that life cannot possibly always act with its conservation, diverseness and perpetuation ‘in mind.’ It isn’t just conceivable but also justifiable to assert that life isn’t intrinsically sustainable, since under its watch the biotic and abiotic world withstood such overwhelming metamorphoses, each of which could have set the stage for irreversible and radical change, rendering the planet inhabitable (Launius, 2012) and much more geologically simple (Gross, 2015) than the Earth we, fortuitously, know today.
Bearing the reflection in mind that life cannot possibly be innately sustainable, one could extend its rationale to more contemporary and menacing predicaments. For starters, the concomitant effect from the rapid growth of the human population, their amplified affluence and both of their enlargement having no end in sight, demands us to inquire on the prospect of reaching a stage in which our species can have a sustainable relation with this planet, in other words, without overshooting carrying capacities. William R. Catton Jr (2012) once again:
“Much human use of planet Earth has been in defiance of this principle, so twentieth-century population growth - and technological advances that enabled some Homo sapiens to develop huge resource appetites and impacts - turned the past human carrying capacity surplus into the present carrying capacity deficit.”
By all means, the unceasing expansion of the human population by about 80 million individuals per year (UNDESA, 2019), on a finite planet, with limited capabilities to harbour not just their basic sustenance requirements but also all their whims and desires calls us to re-evaluate the feasibility of ever achieving a sustainable interaction with the Earth, with ourselves and all other non-human life (Abegão, 2019). Without a doubt, population growth steadily thrusts the repercussions of any degree of collective consumption to a superior level, while contractions in the individual sphere are continuously vanquished by increments to the global population (Engelman, 2009).
Even if we could ignore further population growth as a restriction to fulfilling our pretense of sustainability (Casey, 2019), the fact is that the human population is already severely overpopulated (Dérer, 2018; Vidal, 2012). To be sure, Daily et al. (1994) have defined the optimal population size, which includes goals and targets such as:
“Sufficient wealth, access to resources, universal humans rights, preservation of biodiversity and cultural diversity, and support for intellectual, artistic and technological creativity [for everyone].”
Accordingly, estimates of the amount of energy required to meet these human needs while safeguarding ecosystems, natural resources and wildlife, puts the optimal population size between 1.5 billion and 2 billion people. Comparatively, based on a metric of how much minimal land is required for food production (0.5 hectare per person) and soil conservation Pimentel et al. (1994) have set the upper boundary at 3 billion people. Evidently, these results are strongly contingent on the per capita consumption of the individuals. As a result, Pimentel et al. (2010) considering a European living standard as the baseline for the appropriation of natural resources, constricted the optimal population to 2 billion.
Following from the previously mentioned words of William R. Catton Jr that “[Homo sapiens] turned the past human carrying capacity surplus into the present carrying capacity deficit,” a more recent work from Lianos and Pseiridis (2016) pursued a similar logic in which they calculated an optimal human population that would not deplete Earth’s natural capital. They described this criterion as the ecological footprint-biocapacity ratio (L), respectively, the ecological footprint (Global Footprint Network, 2019) assesses the demand that humanity imposes on the biosphere, while biocapacity appraises its regenerative capacity (Dérer, 2018).
With this in mind, the researchers determined the optimal human population that could use a given maximum gross world product (GWP) (specifically a European level of $11.000) and they concluded that our aggregate cannot be superior to 3.1 billion with that level of affluence. Lianos and Pseiridis (2016) add that if we wish to keep our population in the 7 billion realm, the per capita product must be fundamentally reduced to $4.950, from its current $16.100 (Central Intelligence Agency, 2013). It is worth remembering that as the population continues to increase, austerity will follow, as the pie will have to be cut in ever smaller pieces.
In a final analysis of the optimal human population it is imperative to cite the work of Hatcher (2019), the most meticulous and all-encompassing archive on the subject of carrying capacity. Considering the arguments and the population estimates so far presented, the author takes a more prudent stance by declaring that the human population should not surpass its 1804 CE levels, in detail, when humanity reached its first billion.
Anyone who is struck by the sheer unreasonableness of such a prospect should keep in mind that it wasn’t even a century ago, when the population was just below 2 billion. In fact, it took all of human history for our species to reach that mark in 1927, when it was considered by most of the authors here enunciated to have been the last time humanity was the closest to a state of sustainability. Consequently, nobody will surely argue that the collective existence of our ancestors up until that point was meaningless because they weren’t (conspicuously) breaching ecological limits, if anything, it was more purposeful, as the ‘Great Acceleration’ by way of the “exploding human population and economic growth is driving unprecedented planetary change through the increased demand for energy, land and water” (World Life Fund, 2018).
If on the other hand, the reader is someone who is impermeable to the pressing need to engineer the size of the human populace (Hickey, Rieder & Earl, 2016), please appreciate the observation that neglecting to act compassionately and voluntarily to revert our present growth trend and eventually reduce the human - and livestock - populations will, with a high degree of certainty, result in ecological meltdown and runaway climate change, which will most certainly spell the end of our current civilizational project, and possibly our very existence (Ripple, Wolf, Newsome, Barnard & Moomaw, 2019; Stephen et al. 2018; Ganivet, 2019; Rees, 2019a; Dembicki, 2019; Ahmed, 2019).
Assuming for a moment that humanity is still in a position to change course (or at the very least cushion some of the worst damage), I can’t help but remain sceptical that H. sapiens can muster the will to engage in a collective effort to tackle both the Population and the Affluence factors in the Impact = Population x Affluence x Technology formula (Tschakert et al. 2018). The fact is, that to alter our path we need to come face to face with some very uncomfortable issues, and so far, most prefer to advocate for the delusion of perpetual growth on a finite planet, while personally being convinced of a ‘technological cornucopia’ (Gardner, 2017). This to avoid facing the reality that neither our current way of life or growth of the population can be maintained, and that we will have to scale back both of them to live as our forefathers once did (hopefully with less infant mortality) (O’Neill, Fanning, Lamb & Steinberger, 2018). Nevertheless, for this to happen, significant changes would have to take place.
It is surely welcome that we campaign in the West and other OECD countries for adjustments in overtly hedonistic and self-indulgent lifestyles, as we are aware that the world’s richest 10% produce half of all carbon emissions, while the poorest 3.5 billion account for 10% (Oxfam, 2015). However, as long as the rest of the world emulates those behaviours and the narrative supports more economic growth, we are at the mercy of some very ‘wicked problems’ (Lönngren & Svanström, 2016; Frame, 2008).
Similarly, as I’ve written or implied before (Abegão, 2019a; 2019b), concentrating the debate solely on emissions might be relevant to the existential risk of climate change, but it neglects other more urgent planetary boundaries being breached (Stockholm Resilience Centre, 2019), as it disregards a very distressing dilemma, the ecological impact of the majority of humanity living in a state of poverty (Hassan, Zaman & Gul, 2015; Watmough, Atkinson, Saika & Hutton, 2016; Estrada et al. 2018) and the resulting impacts from lifting that condition (Hubacek, Baiocchi, Feng, Castillo & Sun, 2017; Hubacek, Baiocchi Feng & Patwardhan, 2017).
To put in another way, as recently argued by Maarten Boudry for Quillette (2020):
“Today our planet hosts 7.7 billion people, and our lives are wealthier and healthier than ever before, but if we all lived like our hunter-gatherer forebears, the planet could support about 100 million of us at most. The main reason why our ancestors didn’t wreak even greater ecological havoc is that they numbered too few and died too young.”
It becomes a hard pill to swallow, but as Boudry (2020) adds:
“Even someone who abides by all the latest rules of an eco-friendly lifestyle—eating strictly vegan, never flying, always buying local—will still be responsible for greenhouse gas emissions, for the simple reason that fossil fuels are everywhere: in steel and aluminum, in plastics and paper, in cement and artificial fertilizer, in housing and agriculture. Eight billion people living like climate saints would still produce billions of tons of carbon dioxide every year.”
With this in mind, we have to consider that the sustainable life we have conceived may be completely at odds with our biophysical reality and the sheer number of people engaging in at least the necessary consumption for survival, and more, if given the opportunity, influence its achievability (Kuhlemann, 2018). Assuming, for the sake of argument that everyone would, willingly (extremely unlikely), adopt a ‘sustainable good life,’ the harsh truth is that the human condition which we envision to be associated with ‘sustainability’ would be deeply different.
The team at the Overpopulation Podcast (2018) set out to comment on the results (made for a population of 7 billion, we are already 7.7 billion, so consider further asperity) of the research published in Nature titled A good life for all within planetary boundaries (O’Neill et al. 2018):
“To cut back on consumption sufficient enough for all of us to live sustainably, it would have to really be a dramatic drawdown. It’s not just not having a swimming pool, its consuming everything about half to one-sixth […] within the bio-physical boundaries chosen by the authors, CO2 emissions, nitrogen, phosphorous, freshwater, land-use change, ecological footprint and material footprint and the nations that have the average below the bio-physical limits are Morocco, Guatemala and the Philippines[…] so these living standards are quite a bit below what most of us in the U.S. and the developed world would see as a good quality of life […] looking at the incomes, all of those countries were between 3-5 thousand/per capita income, while the US is at 55 thousand/per capita, so that’s how unsustainable and how dramatically we would have to reduce consumption to work with these bio-physical boundaries [...]
Taking a look at Chad, which has an ecological footprint close to the 1.7 global hectares/per person (minimum biocapacity required for all humanity to live sustainably right now), the most recent data found portrayed a life expectancy of 56, only 48 percent of urban residents have access to potable water and only 2 percent to basic sanitation, there is one television station in the whole country, 24 percent had cell phones in 2010, more than half the population is illiterate.
It is not exactly the typical eco-village when we think about living sustainably! According to the study, if we were all to live all around the world within planetary boundaries, they found the associated life expectancy of 59 years, not all that different from Chad, sanitation only available to 60 percent, 18 percent would be below 1.90$/per day, this is the kind of world one would have to live in to not exceed any of these biophysical boundaries.”