A look back at the environmental destruction left in the wake of humanity’s rise to dominance and how we have reshaped the face of the world, and a look forward at the ways in which we might make amends.
Most of us don’t think that we’re animals or that we’re a part of nature. We people moved out of the wilderness thousands of years ago and named ourselves master over plant, fish, bird, and beast. Because only we have souls, right? And who would want to keep feeding the lions or be limited by the natural world’s ability to nourish us? As we went forth and multiplied, we replaced so much of the natural world with the farms and fields, domesticated plants and animals, cities and roads, and mines and factories that enable billions of people to lead civilized lives. At this point, our conversion of the world into a habitat mainly for humans and the things that we eat is so extensive, most of us have never experienced true wilderness, except on a television or some other screen.
This makes ours a story of success and devastation.
What We’ve Achieved
From time to time, it’s worth pausing to pat ourselves on the back. We’re so busy building new buildings, inventing new things, and expanding our economies that we forget to admire the progress we’ve made that is nothing short of amazing. The art, the architecture, the cultures, and the cuisines that we’ve come up with—and that’s just the start of the alphabet! All of these amazing creations of ours are part and parcel of our growing up of the still growing stock of human beings to more than 8 billion individuals. They wouldn’t have happened without our population growth and our population growth wouldn’t have succeeded so spectacularly without them.
Our population growth is also a crowning achievement. As is the fact that, political, logistical, and financial problems with food distribution aside, we could actually feed all of us and then some. We really are able to produce that much food. That’s how impressive our way with agriculture has become. Meanwhile, with the help of modern medicine, more of us are living to quite ripe old age than ever before.
But All of This Has Come at the Cost of So Much of the Natural World
But here’s the thing. Systems—such as the web of relationships that makes up the biosphere—aren’t generally zero–sum games… for better and for worse. In this case of humanity’s rise and rise, it’s for worse.
In a zero–sum game, there is a fixed amount of a particular resource to go around, be it something like money or food. Any win I make is a loss for my competitors, down to the very penny.
But that’s not what happens in a system as complex as a biosphere made up of interconnected webs of ecosystems. Take just at the food web aspect of it. The food web, in our eat–and–be–eaten natural world, shunts nutrients and energy out to a mind–boggling multitude and diversity of living creatures with literally brutal efficiency. But one species taking a bigger bite out of the food web doesn’t translate into other species getting exactly that much less. There are all sorts of synergistic relationships tied up into the flows of energy and nutrients through the food web that can amplify disturbances with either incredible or disastrous result. For instance, when one species grows amok in an ecosystem (or, in our case, makes a hostile takeover of numerous ecosystems), taking more than its fair share of the food, that ecosystem (or those ecosystems) can choke up and crash.
Case in point–as humanity grew up from 200 million people in the year 1 A.D. (to pick a starting point) to the more than 8 billion we have today, you might expect it would have elbowed the exact same amount of biomass of other animals out of existence. What all that extra biomass of us is eating is what other things are no longer eating. That’s what you’d expect if the food web is a zero–sum game.
But that’s not what happened. Instead—to use a unit of mass that helps us make comparisons across many different types of organisms—humanity’s growth from a mass of 0.0015 billion tons of carbon (plus the mass of all the other elements in our bodies) 2,000 years ago to a mass of 0.06 billion tons of carbon in modern times went hand in hand with the biosphere crashing down from 1,000 billion tons of carbon to 550 billion tons of carbon.
That’s not quite the loss of half of the mass of life on Earth. But at 45%, it’s pretty much close enough that, given the likely errors on the estimate, it might as well be half.
How Do We Know This?
But how do we even know that the biosphere of today is basically only half the shadow of its former self? It’s not like anyone measured how much life there was on Earth 2,000 years ago, before humanity took over like too many ants at a picnic. Or like there’s time machines through which we could dispatch scientists to go make the measurements and then report back to us.
But scientists are all about trying to figure these sorts of things out, generally by creating models—more mathematical and theoretical than tangible—that help us answer questions we can’t get at with direct measurements. In other words, it’s all about making reasonable estimates based on what information we can get our hands on.
Some Numbers Concerning Our Takeover of Earth
At this point, between mapping on the ground and mapping using the view from satellites and airplanes, we have an excellent idea how much land area Earth has: 13.4 billion hectares. From decades of work from ecologists, we also know what kind of ecosystems Earth has and how much carbon they tend to contain per square bit of area. We also know what kinds of ecosystems you’d expect to find in various different places, based on their location and their local climate regime.
We also know that by 2008, we’d covered 0.2 billion hectares of Earth with our cities, roads, and residences. Plus, we’d covered up 5 billion hectares of land with farms and fields, with 70% of that agricultural land being pastureland used to raise animals. That’s a removal of nearly 40% of the biosphere’s land area! Doing the math brings you to the conclusion that we’re using 26% of Earth’s land area as pastureland for livestock.
When you put this all together, the number you come up with for the current mass of the biosphere is that 550 billion tons of carbon mentioned earlier. Most of it, by the way, consists of woody vegetation. There is, to put it bluntly, a lot of carbon in tree trunks.
But if you fill in that 40% of the Earth that we slashed, hacked, and burned through to make room for our farming and ourselves, with the ecosystems you’d expect to find there based on the various climate regimes, terrains, and soils, that’s where the value of about 1,000 billion tons of carbon for the biosphere of 2,000 years ago comes from.
That is an unfathomable amount of prairie, forest, jungle, desert, chapparal, savannah, fen, bog, reef, moor, swamp, and woodland… and all their inhabitants… that is no longer there.
We’ve Forgotten How Savage—and Amazing—the Food Web Is
This is sad for the plants and animals and other organisms who’ve lost their habitats and died out. But it’s also sad for us. We don’t know the nature of nature anymore. We have no idea how it works nor what it is exactly that we’ve lost.
Over the last 15,000 years, as we’ve increasingly developed our practice of agriculture, we’ve broken ourselves out of the delicate web of relationships by which energy and nutrients flow through the food web. Today, instead of appreciating how effectively the food web shunts energy and nutrients out to a dazzling array of organisms, we’re horrified by its barbarity. Who could have invented something so cruel as a world where to survive, most things have to eat something else? And yet, how else could you distribute the energy and nutrients that all these creatures need to survive?
And yet, despite our outrage, we don’t actually grasp how truly almost everything on Earth is born to die—generally quite young—feeding something else.
Consider, for instance, a pair of trees that tend to reproduce sexually instead of cloning themselves by shooting out shoots from their roots. No matter how long the typical lifespan of those two trees—be it 30, 300, or 3000 years—together, they only need to successfully produce two new adult trees that go on to successfully reproduce to do their part in maintaining the numbers of their kind. The rest of the seeds and baby trees they create, eaten by birds, goats, deer, beavers, and other seed–eaters and browsers, are just grist for the food web’s mill.
The case is similar for a pair of sparrows that might hatch 30 chicks over the short course of their lifetime. Only two of those chicks need to survive long enough to successfully reproduce before also becoming someone’s lunch to keep up the population of sparrows.
This sort of math used to be true for humans, too. Out of the eight, ten, or twelve children a woman gave birth to, she needed two to survive to adulthood to have done what was needed to stop the human population from diminishing. For the longest time in human history, between war, accidents, disease, and malnutrition, a woman was indeed lucky if two of them did make it to the point where they were having kids of their own.
That sort of thing was hard on a heart. Not to mention on a body! That’s a lot of birthing to live through and a lot of mouths to feed, if at least briefly.
It also brings up an interesting point. These days, we think of survival of the fittest in terms of the occasional individual doing something stupid and dying. But what the survival of the fittest actually calls for is a staggering number of an individual’s offspring—80%, 90%, 95%, or even more than 99%, in some cases—to succumb to the food web instead of reproducing. This includes the weak, the sick, and the not clever enough, but it also includes the not quite fast enough, not quite strong enough, the otherwise slightly less than optimized, and even the physically and mentally top–notch but unlucky. Wiping out all but the best and luckiest of the best before they can pass on their genes is what survival of the fittest really means. This extreme weeding out is how species stay honed and it is how the food web sees to it that enough of the great diversity of organisms on Earth get fed to maintain that great richness of life.
Now and How We Need to Do Better
Still, given all the grief involved, and the personal hunger pangs and possibilities for starvation, you can understand why we decided to break free of the vicious grip of the food web. It’s so understandable that we opted not to remain constrained by nature, but to take over a vast portion of the Earth’s surface and, via farming, divert its productivity straight into our own mouths. You can also see why we’ve also done something with similarly severe effect on the sea. Via monstrously large and mechanized fishing vessels, we’re appropriating a vast amount of the marine food web for our own need to feed. It is, in this case, about the survival of the most.
But now, what about the rest of the world? Will we keep wiping it out until it gets to the point that we rediscover we can’t live entirely disconnected from Earth’s ecosystems? There are “services” they provide—like oxygen and pollinators, to name just the tip of the iceberg—that we can’t survive without. Or, now that we’ve recognized that the natural world is in such shocking decline and it’s our fault, will we decide to go back to sharing more of the Earth with the rest of the biosphere?
When we’re using 26% of Earth’s land area as pastureland for livestock that we’re eating way too much of for our healthy anyway, that gives us plenty of land that we could gift back to the biosphere and still have all the food we need to eat. We wouldn’t even all need to quit eating meat and dairy, just cut back to a more reasonable level of consumption.
We could also give back a good chunk of the fields that are used to grow greenwashing crops, such as for biodiesel (currently a total of 55 million hectares), cotton (and other crops for material use) to feed our overconsumption of clothing, towels, tablecloths, and other textiles (100 million hectares), and grains that we feed to the livestock when they’re locked up in barns (1 billion hectares). We’d still be producing more than enough high quality food for ourselves, if we converted some of these other fields back to use for growing food that feeds us directly and added them to the 260 million hectares of Earth we currently use for this purpose.
The gains, for the biosphere, could be huge. The gains for us would be enormous as well, and not just because we’d slow down or stop the crash of the ecosystems that we depend on for certain vital “services”. Imagine driving out to the countryside. Every field you would see there now that contains cattle or horses or pigs could be a wild, hooting forest instead, teeming to the gills with life from a few feet down in the soils up to the tops of the tallest of trees. That could be the beginning of the end of the devastation of our success.
Some Further Reading
Bar-On YM, Phillips R, Milo R (2018) The biomass distribution on Earth. Proceedings of the National Academy of Sciences, 115: 6501–6511. www.pnas.org/cgi/doi/10.1073/pnas.1711842115
Jering A, Klatt A, Seven J, Ehlers K, Günther J, Ostermeier A, Mönch L (2013). Sustainable use of global land and biomass resources. Umweltbundesamt. https://www.umweltbundesamt.de/sites/default/files/medien/419/publikationen/130617_englisch_lang_web.pdf
Schramski JR, Gattie DK, Brown JH (2015) Human domination of the biosphere: Rapid discharge of the earth-space battery foretells the future of humankind. Proceedings of the National Academy of Sciences, 112: 9511–9517. https://www.pnas.org/doi/full/10.1073/pnas.1508353112
Smil, V (2011) Harvesting the biosphere: The human impact. Population and Development Review, 37: 613-636.
Captions:
As humanity grew from 0.0015 billion tons of carbon (200 million people) to 0.06 billion tons of carbon (8 billion people), the biosphere as a whole decreased from 1,000 billion tons of carbon to 550 billion tons of carbon as we cleared the land to use to grow crop and pasture domesticated animals.
At this point, humanity has cleared 5.2 billion hectares of land area for agriculture and cities, roads, and other structures. The rest of the land area is unfarmable desert or mountain (4.3 billion hectares) and forest (3.9 billion hectares).