The Humboldt Current
Reflections at the origin of industrial agriculture
If you look at a map of ocean currents in the South Pacific, one of the first things you’ll notice is a strange, serpentine tongue of water curling up the western coast of South America. When current from the South Pole reaches the tip of Cape Horn, a portion of it peels away from the south and begins shaping a path to the north. This new current–the Humboldt current, so named for the nineteenth-century German scientist, Alexander Von Humboldt, the first European to “discover” it–runs parallel to the continent until it comes alongside Peru’s border of Ecuador, four degrees shy of the equator. As if shy of the tropical clime it wandered into, the current tacks to the west, where it quickly disappears into the warm waters of the unimaginatively named Pacific South Equatorial Current.
You’d be forgiven if, like me, you supposed that the Humboldt Current’s isolated path represents a kind of attenuation of oceanic power. On the map, it looks as if the mighty, counter-clockwise circuit of saltwater near the South Pole would slow down when it makes contact with the South American continent. The current’s northward drift seems forced, as if the ocean itself were pushing up against the grain of the continent. Compared to other currents, the Humboldt Current is indeed very slow. It moves a tremendous amount of water, up to 700 million cubic feet per second, but it does so at a fairly leisurely pace: eight or nine miles-per-hour, tops. However, the secret of the Humboldt Current isn’t its size or speed so much as what is happening to it on top: the wind.
In her 2023 book, The Blue Machine: How the Ocean Works, the physicist Helen Czerski asks us to imagine a stack of clean, white copy paper on top of a desk. If you place your hand on top of the stack and push the paper to one side, the top sheet moves about as far as you decide to move your hand. Some of the papers below will move, too. The friction between the lower pages allows the top sheet to pull them along with it. But the force isn’t strong enough for all of them to travel the same distance as the top sheet. Instead, the pieces fan out below, each one travelling a little bit less than the other, until the paper that is furthest from your hand barely moves at all.
Czerski explains that this is more or less what happens whenever wind blows on the surface of the ocean. The warmer surface layers of water get pushed about in different directions, generating most of the planet’s major ocean currents. When this surface water moves, it takes some of the lower, colder layers with it. But like the stack of paper, the further down the water column you go, the less these lower layers tend to move. At the bottom of the ocean, the water barely moves at all.
The same phenomenon happens in the Humboldt Current, but on a different order of magnitude. Trade winds blowing off of the Andes perform a constant stripping away of the warmer layers of water that extend horizontally several hundred miles offshore. A staggering amount of ocean, two hundred meters all the way down, is displaced by the wind. The earth’s rotation causes the water to swerve to the north instead of west with the wind (the so-called Coriolis Effect). And the wind doesn’t just stop: it keeps pushing this column of warm water hundreds of miles up and then out to the Pacific. In its place, frigid, nutrient-dense water from the depth surges to the surface in a mechanism ocean scientists call “upwelling.” “Cold, nutrient-rich water has escaped from underneath the warm lid,” Czerski writes, “and as it comes up to meet the sunshine, all the ingredients for life are there in huge quantities.” Bathed in sunlight and a rich broth of nutrients, the phytoplankton “gorge themselves silly on sunlight, stashing away solar energy on a monumental scale.”
“Monumental” undersells it. The explosion of phytoplankton in the Humboldt Current supports the most productive fishery in the world. In a body of water that makes up roughly .05 per cent of the ocean’s surface, the Humboldt Current consistently generates 15 to 20 percent of the global fish catch every year. The majority of this catch is made up of the Peruvian anchoveta, a small, foul-smelling anchovy that is edible, but not palatable, to humans. Once caught, the anchoveta are processed, dried, pulverized, and shipped all over the world in the form of fishmeal. It’s not uncommon for harvests to reach 5 or 6 million metric tons annually. The two fishing seasons in 2024 combined to haul in nearly 8 million tons.
What is done with this abundant harvest of marine life? A tiny percentage of Peruvian anchoveta is pressed into fish oil, which is pumped into pills and sold as a dietary supplement for humans. The rest–ninety-eight per cent of every anchoveta harvest–is destined for animal feed, primarily farmed fish and hogs. So dependent has modern agriculture become on the Peruvian anchoveta that, in 1972, when the anchoveta fishery collapsed, the price of bacon in the UK doubled instantly. In the US, the price jumped by one third.
After reading Czerski’s book, I checked my feed labels. It’s true: the twelve hogs I tend two hundred miles from the coast have a little bit of the ocean, perhaps even the Humboldt Current, inside of them. It’s likely that my chickens do, too. (According to trade groups, Peru accounts for 20 per cent of global fishmeal and fish oil supplies). I’m embarrassed to say that I hadn’t noticed the ingredient before. When piglets are weaned, they are fed a special ration that contains fishmeal. Once they get to fifty pounds, their protein needs shift, and they switch to a feed without fishmeal. I’m told by my ‘feed guy’ that hogs fed on fishmeal their whole lives have an unpleasant fishy smell. Call it the revenge of the anchoveta.
Animal feed is big business. It’s been big business for as long as agriculture has been conducted on an industrial scale. Very large numbers of domestic animals require very large amounts of food. One source of cheap protein is fishmeal; another is soy. Like fishmeal, the majority of soybeans (77%, roughly, according to the UN) produced around the world go to animals like pigs and chickens, not humans. In the US, over a third of corn goes to feed non-human animals. There are, right now, three quarters of a billion hogs alive on earth. Half of them live in China. That’s quite the evolutionary coup for a species that, not very long ago, humans once tended in very small numbers, in their backyards and or woodlots, to graze tree mast and utilize kitchen waste.
From one perspective, then, the Humboldt Current’s role in the global agricultural economy makes a certain kind of sense, which is to say that it makes as much sense as the human appetite for swine flesh does. Agricultural systems reflect human appetites. By looking in the mirror, we can see very quickly that what we want is cheap meat and sugar–and that most of us don’t want to do the work of raising our own food. Certain crops or animals or marine ecosystems lend themselves to industrial-scale exploitation because they can, with careful study or technological tweak, withstand it. They are cheap precisely because they can be grown and harvested or managed at scale.
Czerski’s book isn’t much interested in these systems and the role the ocean plays (or has played) within them. That’s fair, I suppose; her job in the book is to explain the physics of oceans in ways that people like me, people who are bad at math, can understand. What’s odd, though, is how the history of these systems seeps into the language she uses to describe the oceanic mechanisms that make biotic life possible on the planet. Her metaphors for the ocean revolve almost obsessively around the steam engine, the distinctive invention–and engine–of industrial capitalism. It’s not that the metaphor of ocean-as-engine doesn’t work, but that it works too well. The ocean is a machine of life; the ocean is a machine of industrial capitalism. Chapter one opens in a technology park on Kona, in Hawaii, where technology start-ups are trying to figure out how to use temperature differential in the ocean to generate cheap energy. By the end of the book, it’s sometimes hard to know where one machine begins and the other ends:
Earth’s blue is closely connected to the other global components: atmosphere, the ice, life and the land, and all five work together as a single system. But the ocean is the big beast in Earth’s planetary machinery. The engine that is Earth’s ocean takes sunlight and converts it into giant underwater currents and waterfalls, hauling around the ingredients for life: nutrients, oxygen and trace metals like potassium and iron, shaping our coasts and transporting heat. This isn’t just another engine, it’s the grandest one of all: an engine the size of a planet. It’s got all the elegance of the most ingenious human-built engines but the mechanics here are more subtle and intricate. Instead of a nice tidy piston, we’re faced with a flow of water that merges into the water on either side of it; it’s definitely up to something, but it’s hard to say where this pushes on that. But it is absolutely still an engine, converting light and heat into movement in myriad different ways.
Subtle and intricate, but where the tidy pistons and or shiny brass widgets would be, we get water, wind, underwater current, and hidden waterfalls. Each subtlety of current or variance in temperature adds up to “an engine the size of a planet.” (Is this phrase about the ocean or scifi dystopia?) However, in the conclusion, we find out that this metaphor, which seemed so elegant and straightforward, isn’t. The ocean is not a self-contained hydraulic machine for biological life. In fact, precisely because we’ve been acting as if the ocean were a machine that supplies us with endlessly renewable resources that the ocean may soon turn around and start dominating us.
Czerski explains that for the last hundred years, the ocean has been softening the blow of climate change by absorbing excess heat from the atmosphere. But its ability to do so is coming under strain: “the addition of extra heat at the surface is reinforcing the layered structure and therefore acting as a brake on the vertical turning over of the blue machine.” Putting a break on the oceanic machine means drastic changes in weather patterns and the intensification of storms.1 It also means that life in the ocean regenerates more slowly than before. Because of overfishing, the sea, is now devoid of ninety per cent of the largest class of creatures that once called the ocean home (whales). Sixty per cent of creatures with a biomass over ten grams has also disappeared.2 It’s difficult to imagine how these numbers could rebound within any of our lifetimes without drastic, immediate intervention.
Appropriately, the language in this section of the book abandons machines and engines and embraces interdependence and ecology. The implication is that, if we simply make more tweaks to the machines we do in fact control, the machines of global capitalism, then the oceanic engine can recalibrate itself and go on sustaining life in all its human and non-human plenitude. “We have to be very careful about what we do in the ocean, because it’s easy to be blind, either deliberately or accidentally, to the full picture.”3 But who exactly is included in the “we” who operate the levers of capitalism? Is it reasonable to assume that we can attain the full picture of the ocean from within an economic system that is designed to abscond matter from one place and consume it on the other side of the world?
Europeans first came to the Humboldt Current because of the massive deposits of guano, or bird shit, on a chain of islands called the Chinchas that sit in the middle of the Current. Czerski mentions this, but what she doesn’t say is that this discovery utterly transformed the way Europeans did agriculture.
For thousands of years, ocean-going birds have feasted on the seemingly miraculous numbers of fish swimming in the Humboldt. Pelicans, boobies, and cormorants all make their nests on the Chinchas. There’s no rain to wash the excrement away, so it dries and accumulates. The current’s extremely cold waters, coupled with the rain shadow effect of the Andes, keeps this region among the driest on earth. The Atacama Desert in Chile, just inland of the Current, is the most arid non-polar desert in the world.
When Von Humboldt first travelled to the Chincha Islands, he recorded layers of the acrid-smelling stuff three meters deep. Because of the courses he took in chemistry, he knew it had to contain lots of ammonia. But he rejected the explanation that indigenous people gave him (that the guano mounds came from the birds) and surmised that the pungent substance was left behind after some prehistoric cataclysm. In any case, Humboldt shipped back samples to his colleagues all over Europe. The English chemist, Humphrey Davy, a close friend and companion to Samuel Taylor Coleridge, published one of the first chemical analysis of guano in 1813. He instantly realized the value of the substance. Guano, he wrote, was chock full of uric acid, phosphoric acid, lime, and potassium salt. It could be a boon to capitalist farmers, who were experiencing declining crop yields and infertility. To Davy, Peruvian guano demonstrated beyond the shadow of a doubt that God Himself had set down “the modification of the soil, and the application of manures [...] within the power of man, as if for the purpose of awakening his industry, and of calling forth his powers.”4 The guano of the Humboldt Current and the exhausted soils of Europe were two pieces of a puzzle God intended humans to solve. And solve it they did.
Davy’s Elements was translated into a number of languages, including Spanish and Hungarian. His and other popular reports about the potency of Peruvian guano kicked off a bonanza of military expansion to the South Pacific. Numbers help clarify the scale of what unfolded in the decades that followed. During the 18th century, when the Dutch East India Company controlled the South Asian nitrate trade, around 100 tons of guano were imported annually into Europe. By 1800, the British East India Company had supplanted their rivals, hauling in approximately 1,000 tons per year. However, as the historian Gregory T. Cushman notes, “Peruvian nitrate imports immediately dwarfed these numbers, rising from an average of 2,500 tons per year in the 1830s, to 17,000 tons in the 1840s, to 42,000 tons in the 1850s.”5 By the 1890’s, Peru was exploring around a million tons of nitrates from the Chinchas Islands and the Atacama all around the world. Peruvian guano was quite literally feeding the industrialization of the Northern hemisphere.
Cushman proposes calling the period of global history from 1802 to 1884 “the age of shit.”6 He means the phrase literally and figuratively. Haunted by Thomas Malthus’s grim pronouncement that population growth regularly exceeds agricultural production, many of the leading minds of Europe were interested in agricultural productivity and the possibility of turning political economy into a formal object of study. They became obsessed with the properties of animal dung–particularly guano. “Rather than improving the world’s food supply,” Cushman writes, “Peruvian guano mainly served northern consumers of meat and sugar.” And instead of “inaugurating an epoch of peace and prosperity,” rapacity for guano and nitrates inspired some particularly vicious conflicts: the Chincha Islands War (1865-1866), which granted Peru’s independence from Spanish rule, and the War of the Pacific (1879-1884).
To the chagrin of abolitionists in the United States, the search for guano encouraged the seizure of new lands and the expansion of slavery. In 1856, the US passed the Guano Act, which allowed US citizens to lay claim to any uninhabited island that had guano on it. The authors of this legislation reasoned that these islands were effectively a public commons, and therefore could be taken at will by anyone who “demonstrated” need. (Of the sixty-six islands US citizens seized, nine remain in US possession.) However important slaves were to the American capitalists who harvested the nitrates they found in the South Pacific, the new global industry of nitrate production found different ways of adapting to life without the peculiar institution. When Peru achieved independence in 1826 and Great Britain abolished slavery (1833), British capitalists pivoted and perfected the infamous “coolie” system of labor by importing hundreds of thousands of bonded Chinese workers into Peru and Chile. These people labored under some of the most extreme conditions imaginable. One contemporary English eyewitness described that these workers,
[...] besides being worked almost to death, [...] have neither sufficient food nor passably wholesome water. Their rations consist of two pounds of rice and about half a pound of meat. This is generally served out to them between ten and eleven in the morning, by which time they have got through six hours’ work. Each man is compelled to clear from four to five tons of guano a day. During the last quarter of 1875, it is reported that there were 355 Chinamen employed at Pabellon de Pica alone, of whom no less than 98 were in the hospital. The general sickness is swelled legs, caused, it is supposed, by drinking condensed water not sufficiently cooled, and by a lack of vegetable diet. The features of this disease are not unlike those of scurvy or purpura.7
Around the same time, the US consul to Peru noted in a letter that the suicide rate of the Chinese workers who dug guano was so high that the British had to put armed guards “around the shores of the Guano Islands, where they are employed, to prevent them from committing suicide by drowning, to which end the Coolie rushes in his moments of despair.” Guano workers in the early twentieth century reported that they still found bones and the tattered garments of Chinese workers scattered around the islands.
Perhaps the greatest irony of the age of shit is that the importation of guano ended up ruining the soils that it was intended to improve. (It also ruined nations: DNA sequencing suggests that the Peruvian guano trade may have been responsible for the arrival of the P. infestans strain that led to the Great Famine.) Initial returns in Europe and America were good, really good. On both sides of the Atlantic, large landowners touted stupendous crop yields in journals and newspapers addressed to the gentleman farmer. By the 1840s, slaves and sharecroppers in the US were pooling resources to import guano together. Over time, however, farmers found that guano tended to cause soil productivity to decline. This is because plants aren’t able to absorb nitrates unless there is a minimum of other necessary compounds available to them in the soil. (It has also been shown that excess soil nitrogen inhibits the bloom of biological life in the soil. The same is true of modern synthetic fertilizers.) The so-called “law of the minimum,” first articulated by the German chemist Justus von Liebig [1803-1873], brought the guano craze to a sudden halt. In Letters on Modern Agriculture, Liebig spared no British or American farmer for misusing guano. While the Americans were guilty of the worst land abuse–an “open system of [soil] robbery,” he called it–the British practiced a “more refined system of spoliation”: “Good fortune kindly sent guano to rescue them in their utmost need,...but in their fatal hands, this blessing actually turned into an instrument for impoverishing the land in the course of time more completely.”8 Many others joined Liebig’s complaint. But none of the polemic did anything to curtail modern agriculture’s addiction to off-farm inputs.
The anchoveta industry accounts for a much larger proportion of the Peruvian economy than guano does. Guano is still harvested off the coast of Peru and Chile, but the industry is regulated very tightly. Conservationists crisscross the Chinchas every year, ensuring that the harvest of manure doesn’t disturb the populations of sea birds. Since the collapse of the guano industry, global agriculture has pivoted. Nowadays, the majority of fertilizers used in conventional agriculture are produced by artificial means. A byproduct of the munitions industry in World War I, nitrogen fertilizer is made by subjecting atmospheric nitrogen and hydrogen from natural gas to extremely high temperatures and pressures. Rock phosphate is mined below the surface of the earth and then mixed with sulfuric acid to make phosphate fertilizer. One of the largest phosphate mines–in fact, the largest integrated mine and chemical plant in the world, the Aurora Phosphate Mine–lies a hundred miles east of my farm. The mine is located on top of an ancient sea bed that houses the remains of countless prehistoric sea creatures. The phosphorus is in those remains.
Accounting for these changes, it’s still worth asking whether the age of shit has really ended. We’re no longer scanning the globe for large caches of animal manure, but our dependence on the extraction and global distribution of very specific substances from very particular places is every bit as acute as it was during the guano age. If extraction and distribution are what the guano age was all about, then it is hard to believe that we’ve left it. The Humboldt Current is hardly an exception in this history, and it’s not just all about the extraction of fossil fuels (as important as this story is). To take a few of the most salient contemporary examples: the town of Spruce Pine, North Carolina, one of the few places in the world where the pure quartz necessary for computer chips and solar panels can be found. The cobalt mines of the Democratic Republic of Congo, where thousands of modern-day slaves scrape the ground for chunks of blue mineral that go into electric car batteries and rechargeable household devices. Where I live, the soils have been strip mined for so long that the ground is mostly prized for what can go on top of it: data centers, natural gas storage and distribution, conurbation.
Meanwhile, global agriculture is more reliant on off-farm inputs than ever. This is insane: studies suggest that crops absorb about 50 per cent of the nitrogen and phosphate fertilizers that are applied to them. Some residue from the other half leaches into groundwater. The rest finds its way into the ocean, where it creates vast “dead zones” for marine life. One dead zone, in the gulf of Oman, is the size of the US state of Florida. And these zones are growing. A recent study found that the dead zone in the Gulf of Mexico has reached 4,298 square miles, two times larger than the 2035 reduction target.
There are still reasons to believe that small, sustainable farms are the future of agriculture. According to different metrics, small farms still account for a large percentage of global food production.9 Also, small farms are still almost certainly more productive per acre than industrial farms. People like David Schlossberg and Chris Smaje have argued that there is an insurgent politics lying dormant within key sustainability movements (energy, fashion, food). However, despite localized enthusiasm in the US, there’s little evidence of governments taking small farms very seriously, or considering what the future of agriculture might look like beyond the age of shit.
220.
222-3.
230.
Elements of Agricultural Chemistry: In a Course of Lectures for the Board of Agriculture Delivered between 1802 and 1812 (London, 1839), v, 16, 279–80; quoted in The Guano Age, 52.
Guano Age, 66.
74.
Quoted in Still, Larding the Lean Land; See also Watt Stewart, “Chinese Bondage in Peru: A History of the Chinese Coolie in Peru: 1849–1874” (Westport, CT: Greenwood, 1951), 96–98; and Brett Clark, Daniel Auerbach, and Karen Xuan Zhang, “The Du Bois Nexus: Intersectionality, Political Economy, and Environmental Injustice in the Peruvian Guano Trade in the 1800s,” Environmental Sociology 4, no. 1 (2018): 54–66.
Cushman, 66.
https://www.weforum.org/stories/2021/10/fuel-food-work-world-farms-agriculture/