by Andrea Wulf
On 7 February 1800, Humboldt, Bonpland and José, their servant from Cumaná, departed from Caracas on four mules, leaving behind most of their luggage and collections. To reach the Orinoco, they would have to head south on an almost exactly straight line through the huge emptiness of the Llanos – vast plains the size of France. The plan was to go to the Rio Apure, a tributary of the Orinoco about 200 miles to the south of Caracas. There they would procure a boat and provisions for their expedition at San Fernando de Apure, a Capuchin mission. First, though, they would go west, on a 100-mile detour to see the lush valleys of Aragua, one of the wealthiest agricultural regions in the colonies.
With the rainy season over, it was hot and much of the land through which they rode was arid. They crossed mountains and valleys, and after seven exhausting days, they finally saw the ‘smiling valleys of Aragua’. Stretching west were endless neat rows of corn, sugarcane and indigo. In between they could see small groves of trees, little villages, farmhouses and gardens. The farms were connected by paths lined with flowering shrubs and the houses shaded by large trees – tall ceibas clothed in thick yellow blossoms with their branches plaited into the flamboyant orange blooms of coral trees.
In the midst of the valley and surrounded by mountains was Lake Valencia. About a dozen rocky islands dotted the lake, some large enough to pasture goats and to farm. At sunset thousands of herons, flamingos and wild ducks brought the sky alive as they flew across the lake to roost on the islands. It looked idyllic but, as the locals told Humboldt, the lake’s water levels were falling rapidly. Vast swathes of land that only two decades earlier had been under water were now densely cultivated fields. What had once been islands were now hillocks on dry land as the shoreline continued to recede. Lake Valencia also had a unique ecosystem: with no outflow to the ocean and only small brooks running in, its water levels were regulated by evaporation alone. The locals believed that an underground outlet drained the lake, but Humboldt had other ideas.
Lake Valencia in the Aragua Valley (Illustration Credit 4.3)
He measured, examined and questioned. When he found fine sands on the higher levels of the islands, he realized that they had once been submerged. He also compared the annual average evaporation of rivers and lakes across the world, from southern France to the West Indies. As he investigated, he concluded that the clearing of the surrounding forests, as well as the diversion of water for irrigation, had caused the falling water levels. As agriculture had flourished in the valley, planters had drained and diverted some of the brooks that fed into the lake to irrigate their fields. They had felled trees to clear land, and with it the forest’s undergrowth – moss, brushwood and root systems – had disappeared, leaving the soils beneath exposed to the elements and incapable of water retention. Just outside Cumaná, locals had already told him that the dryness of the land had increased in tandem with the clearing of ancient groves. And on the way from Caracas to the Aragua Valley, Humboldt had noted the dry soils and bemoaned that the first colonists had ‘imprudently destroyed the forest’. As the soils had become depleted and fields had yielded less, the planters had moved west along a path of destruction. ‘Forest very decimated,’ Humboldt scribbled in his diary.
Just a few decades previously, the mountains and foothills that surrounded the Aragua Valley and Lake Valencia had been forested. Now, with the trees felled, heavy rains had washed away the soil. All this was ‘closely connected’, Humboldt concluded, because in the past the forests had shielded the soil from the sun and thereby diminished the evaporation of the moisture.
It was here, at Lake Valencia, that Humboldt developed his idea of human-induced climate change. When he published his observations, he left no doubt what he thought:
When forests are destroyed, as they are everywhere in America by the European planters, with an imprudent precipitation, the springs are entirely dried up, or become less abundant. The beds of the rivers, remaining dry during a part of the year, are converted into torrents, whenever great rains fall on the heights. The sward and moss disappearing with the brush-wood from the sides of the mountains, the waters falling in rain are no longer impeded in their course: and instead of slowly augmenting the level of the rivers by progressive filtrations, they furrow during heavy showers the sides of the hills, bear down the loosened soil, and form those sudden inundations, that devastate the country.
A few years earlier, when working as a mining inspector, Humboldt had already noted the excessive clearing of forests for timber and fuel in the Fichtel Mountains near Bayreuth. His letters and reports from that time were peppered with suggestions on how to reduce the need for timber in mines and ironworks. He had not been the first to comment on this but previously the reasons for concern had been economical rather than environmental. Forests provided the fuel for manufacturing, and timber was not only an important building material for houses but also for ships which in turn were essential for empires and naval powers.
Timber was the oil of the seventeenth and eighteenth centuries, and any shortages created similar anxieties about fuel, manufacturing and transport, as threats to oil production do today. As early as 1664, the English gardener and writer John Evelyn had written a bestselling book on forestry – Sylva, a Discourse of Forest Trees – in which he addressed timber shortage as a national crisis. ‘We had better be without gold than without timber,’ Evelyn had declared, because without trees there would be no iron and glass industries, no blazing fires warming homes during cold winter nights, nor a navy to protect the shores of England.
Five years later, in 1669, the French Minister of Finance, Jean-Baptiste Colbert, had outlawed much of the communal right to use the forests in villages, and had planted trees for the navy’s future use. ‘France will perish for the want of wood,’ he had said on introducing his draconian measures. There had even been some lone voices in the vast lands of the North American colonies. In 1749 the American farmer and plant collector John Bartram had lamented that ‘timber will soon be very much destroyed’ – a concern echoed by his friend Benjamin Franklin who had also feared the ‘loss for wood’. As a solution Franklin had invented a fuel-efficient fireplace.
Now, at Lake Valencia, Humboldt began to understand deforestation in a wider context and projected his local analysis forward to warn that the agricultural techniques of his day could have devastating consequences. The action of humankind across the globe, he warned, could affect future generations. What he saw at Lake Valencia he would see again and again – from Lombardy in Italy to southern Peru, and many decades later in Russia. As Humboldt described how humankind was changing the climate, he unwittingly became the father of the environmental movement.
Humboldt was the first to explain the fundamental functions of the forest for the ecosystem and climate: the trees’ ability to store water and to enrich the atmosphere with moisture, their protection of the soil, and their cooling effect.1 He also talked about the impact of trees on the climate through their release of oxygen. The effects of the human species’ intervention were already ‘incalculable’, Humboldt insisted, and could become catastrophic if they continued to disturb the world so ‘brutally’.
Humboldt would see again and again how humankind unsettled the balance of nature. Only a few weeks later, deep in the Orinoco rainforest, he would observe how some Spanish monks in a remote mission illuminated their ramshackle churches with oil harvested from turtle eggs. As a consequence, the local population of turtles had already been substantially reduced. Every year the turtles would lay their eggs along the river’s beach, but instead of leaving some eggs to hatch the next generation, the missionaries collected so many that with every passing year, as the natives told Humboldt, their numbers had shrunk. Earlier, at the Venezuelan coast, Humboldt had also noted how unchecked pearl fishing had completely depleted the oyster stocks. It was all an ecological chain reaction. ‘Everything,’ Humboldt later said, ‘is interaction and reciprocal.’
Humboldt was turning away from the human-centred perspe
ctive that had ruled humankind’s approach to nature for millennia: from Aristotle, who had written that ‘nature has made all things specifically for the sake of man’, to botanist Carl Linnaeus who had still echoed the same sentiment more than 2,000 years later, in 1749, when he insisted that ‘all things are made for the sake of man’. It had long been believed that God had given humans command over nature. After all, didn’t the Bible say that man should be fruitful and ‘replenish the earth, and subdue it: and have dominion over fish of the sea, and over fowl of the air, and over every living thing that moveth upon the earth’? In the seventeenth century the British philosopher Francis Bacon had declared, ‘the world is made for man,’ while René Descartes had argued that animals were effectively automata – complex, perhaps, but not capable of reason and therefore inferior to humans. Humans, Descartes had written, were ‘the lords and possessors of nature’.
In the eighteenth century ideas of the perfectibility of nature dominated western thinking. Humankind would make nature better through cultivation, it was believed, and ‘improvement’ was the mantra. Orderly fields, cleared forests and neat villages turned a savage wilderness into pleasing and productive landscapes. The primeval forest of the New World by contrast was a ‘howling wilderness’ that had to be conquered. Chaos had to be ordered, and evil had to be transformed into good. In 1748 the French thinker Montesquieu had written that humankind had ‘rendered the earth more proper for their abode’ – with their hands and tools making the earth habitable. Orchards loaded with fruits, tidy vegetable gardens and meadows grazed by cattle were the ideal of nature at the time. It was a model that would long rule the western world. Almost a century after Montesquieu’s assertion, the French historian Alexis de Tocqueville, during a visit to the United States in 1833, thought that it was ‘the idea of destruction’ – of man’s axe in the American wilderness – that gave the landscape its ‘touching loveliness’.
Some North American thinkers even argued that the climate had changed for the better since the first settlers arrived. With every tree that was cut from the virgin forest, they insisted, the air had become healthier and milder. Lack of evidence didn’t stop them from preaching their theories. One such was Hugh Williamson, a physician and politician from North Carolina, who published an article in 1770 that celebrated the clearing of huge swathes of forests, which, he claimed, was to the benefit of the climate. Others believed that clearing the forests would increase winds which in turn would carry healthier air across the land. Only six years before Humboldt’s visit to Lake Valencia, one American had proposed that felling trees in the interior of the continent would be a useful way of ‘drying up the marshes’ along the coast. The few voices of concern remained restricted to private letters and conversations. On the whole the ‘subduing of the wilderness’, most agreed, was the ‘foundation for future profit’.
The man who had probably done most to spread this view was the French naturalist Georges-Louis Leclerc, Comte de Buffon. During the mid-eighteenth century Buffon had painted a picture of the primeval forest as a horrendous place full of decaying trees, rotting leaves, parasitic plants, stagnant pools and venomous insects. The wilderness, he said, was deformed. Though Buffon had died the year before the French Revolution, his views of the New World still shaped public opinion. Beauty was equated with utility and every acre wrested from the wilderness was a victory of civilized man over uncivilized nature. It was ‘cultivated nature’, Buffon had written, that was ‘beautiful!’.
Humboldt, however, warned that humankind needed to understand how the forces of nature worked, how those different threads were all connected. Humans could not just change the natural world at their will and to their advantage. ‘Man can only act upon nature, and appropriate her forces to his use,’ Humboldt would later write, ‘by comprehending her laws.’ Humankind, he warned, had the power to destroy the environment and the consequences could be catastrophic.
1 Humboldt later put it succinctly: ‘The wooded region acts in a threefold manner in diminishing the temperature; by cooling shade, by evaporation, and by radiation.’
5
The Llanos and the Orinoco
AFTER THREE WEEKS of intense investigations at Lake Valencia and the surrounding valley, Humboldt finished his observations. It was time to turn south towards the Orinoco, but first they had to cross the Llanos. On 10 March 1800, almost exactly a month after leaving Caracas, Humboldt and his small team entered the bleak tussocky grassland of the Llanos.
The land was crusted in dust. The plains seemed to stretch out for ever and the horizon danced in the heat. They saw clumps of dried grass and palms but not much else. The relentless sun had baked the ground into a cracked hard surface. Sticking his thermometer in the ground, Humboldt recorded a temperature of 50ºC. Having left behind the densely populated Aragua Valley, Humboldt felt suddenly ‘plunged into a vast solitude’. Some days the air stood so still, he wrote in his journal, that ‘everything seems motionless’. With no clouds to shade them as they trekked across the hardened soil, they stuffed their hats with leaves as insulation against the burning heat. Humboldt wore loose-fitting trousers, a waistcoat and simple linen shirts. He had a coat for colder climates and always wore a soft white necktie. He had chosen the most comfortable European clothes available at the time – light and easily washable – but even dressed like this, he found it unbearably hot.
In the Llanos they encountered dust devils, and frequent mirages conjured up cruel promises of cool and refreshing water. Sometimes, they travelled during the night to avoid the scorching sun. They often went thirsty and hungry. One day they came across a small farm – nothing more than a solitary house with a few small huts around it. Covered in dust and burned by the sun, the men were desperate for a bath. With the landowner absent, the foreman pointed them to a nearby pool. The water was murky but at least a little cooler than the air. Excitedly, Humboldt and Bonpland stripped off their dirty clothes, but just as they stepped into the pool, an alligator that had been lying motionless on the opposite bank decided to join them. Within seconds the two men had jumped out and grabbed their clothes, running for their lives.
Humboldt and his team in the Llanos (Illustration Credit 5.1)
Although the Llanos might have been an inhospitable environment, Humboldt was enthralled by the vastness of the landscape. There was something about the flatness and its daunting size that ‘fills the mind with the feeling of infinity’, he wrote. Then, about halfway across the plains, they reached the small trading town of Calabozo. When locals told Humboldt that many of the shallow pools in the area were infested with electric eels, he couldn’t believe his luck. Since his experiments with animal electricity in Germany, Humboldt had always wanted to examine one of these extraordinary fish. He had heard strange tales about the five-foot-long creatures that could deliver electric shocks of more than 600 volts.
The problem was how to catch the eels given that they lived buried in the mud at the bottom of the pools and thus could not be easily netted. The eels were also so highly charged that touching them would mean instant death. The locals had an idea. They rounded up thirty wild horses in the Llanos and drove the herd into the pond. As the horses’ hooves churned up the mud, the eels wriggled up to the surface, giving off enormous electric shocks. Entranced, Humboldt watched the gruesome spectacle: the horses screamed in pain, the eels thrashed beneath their bellies, and the water’s surface boiled with movement. Some horses fell and, trampled by the others, drowned.
The battle between horses and electric eels (Illustration Credit 5.2)
Over time the strength of the electric shocks diminished and the weakened eels retreated into the mud from where Humboldt pulled them with dry wooden sticks – but he hadn’t waited long enough. When he and Bonpland dissected some of the animals, they endured violent shocks themselves. For four hours they conducted an array of dangerous tests including holding an eel with two hands, touching an eel with one hand and a bit of metal with the other, or Humboldt touch
ing an eel while holding Bonpland’s hand (with Bonpland feeling the jolt). Sometimes they stood on dry ground, at others on wet; they attached electrodes, poked the eels with wet sticks of sealing wax and picked them up with wet clay and fibre cords made from palms – no material was left untested. Unsurprisingly, by the end of the day Humboldt and Bonpland felt sick and feeble.
The eels also made Humboldt think about electricity and magnetism in general. Watching the grisly encounter between eels and horses, Humboldt thought of the forces that, variously, created lightning, bound metal to metal and moved the needles of compasses. As so often, Humboldt started with a detail or an observation, and then spun out to the greater context. All ‘flow forth from one source’, he wrote, and ‘all melt together in an eternal, all-encompassing power’.
At the end of March 1800, almost two months after leaving Caracas, Humboldt and Bonpland finally reached the Capuchin mission in San Fernando de Apure at the Rio Apure. From here they would paddle east along the Rio Apure and through the rainforest to the Lower Orinoco – a distance of about a hundred miles as the crow flies, but more than double that length along the looping river bends. Once they reached the confluence of the Rio Apure and the Lower Orinoco, their intention was to travel south along the Orinoco and across the great Atures and Maipures rapids, deep into a region where few white men had ever gone. Here they hoped to find the Casiquiare, the fabled link between the great Amazon and Orinoco.