Humans have also been a part of this ecosystem, relying almost exclusively on rivers and lakes for drinking, bathing, food, waste disposal and transport. Fresh water is so essential to humans that you can map society by it. River deltas have proved fertile culturally as well as agriculturally – the great religions have rivers as gods, such as the Ganges, or as important parts of their narrative, such as Moses’ journey on the Nile, or Jesus’ baptism in the Jordan. Historically, cities were built in fertile river valleys and at river mouths. Agricultural run-off of sediment, water and nutrients created rich coastal deltas that could support greater food production. This and the good maritime and river connections for trade and transport made deltas ideal places to live. Human civilisation was born on a riverbank. The Tigris, Euphrates, Indus and Nile spawned humankind’s first great experiments in urban living, shifting our species firmly on to the trajectory we have followed ever since.
In the Anthropocene, humanity is draining the world’s rivers and other sources of fresh water. Climate change has altered the global water cycle from Holocene norms, intensifying evaporation and precipitation. There is now greater flooding, worsening droughts and a general loss of predictability that makes planning more difficult for people trying to adapt. Greater water extractions by humans for agriculture, industry and energy mean that many rivers have dried up, while others are now too polluted to use.
Of all the ways we’ve engineered Earth in the Anthropocene, little rivals our audacious planetary-wide replumbing of the world’s waterways. We have straightened and diverted them, buried them, dammed them and drained them for irrigation, filled or emptied them of fish, dug their beds for construction materials, used their flows to drive turbines for hydropower, and even created our own canals to bridge cities and divide continents. Humans now control more than two-thirds of the world’s fresh water. We’ve captured so much water that we’ve redistributed its weight around the world and the globe now spins a fraction slower.
In the past century, we have drained half of the world’s wetlands, built 48,000 large dams and diverted most of the world’s large rivers – only 12% still run freely now from source to sea.1 Major rivers, such as Mexico’s Rio Grande, China’s Yellow River and Australia’s Murray River, frequently no longer reach the sea. Inland seas, such as the Aral or Lake Chad, have dried up with the use for agriculture of their feeder rivers. Dams, diversions and extractions are preventing river sediments from flowing downstream to maintain deltas against erosion. That, combined with groundwater extraction in coastal cities, is causing two-thirds of major deltas to sink.2 Around a quarter of people rely on groundwater that is being extracted faster than it is being replenished, more than 800 million have no safe drinking water at all, while four in five of us live in a place where the water supply is at risk.3 It’s not just humans that get thirsty, all species need water, and ecosystems around the world are suffering from a decline in supply – 30% of freshwater species are now endangered, the highest proportion of any ecosystem.4
And our demands on the planet’s rivers are growing ever greater. Despite all the ways we’ve cosseted ourselves in the Anthropocene against the hazards and unpredictability of the natural world, we remain desperately dependent on rivers for drinking, for agriculture, for fisheries and, increasingly, for our energy.
In many ways, the Anthropocene will be shaped by how we manage our rivers – it’s already proving emotive and political territory in different parts of the world.
The southernmost habitable region of our planet is an untamed wilderness of glaciers and mountain peaks, subantarctic forest and scrub desert, volcanoes and turquoise lakes. Home to condors, puma and blue whales, Patagonia is the tail end of the Americas, one of the last accessible nowhere lands on Earth and the jumping-off point for Antarctica. It contains the Southern Ice Field, the world’s most important reserve of fresh water after Antarctica and Greenland. Forests of Antarctic beech bear testimony to a time when these lands were part of the warm Gondwana supercontinent, while frequent earthquakes and fiery volcanoes are evidence of continuing geological movement.
This extraordinary landscape is the focus of a bitter international battle over plans to build a cluster of hydroelectric dams on three of Chile’s mightiest rivers. It is an issue so divisive, it is tearing apart some of the country’s biggest corporations and risks unseating the president. I went there in the hope of learning whether in the Anthropocene, people will choose the promise of cheap electricity and associated economic development, or the preservation of a natural wilderness that few will ever visit.
Deep in the heart of Patagonia, I find the churning glacial blue of Chile’s most voluminous river, the Baker. The river cuts fast and furious through the mountains here, a tumultuous pulse that roars in defiance of any checks or dams. It is wild, wet and loud. Rainbows flash in the spray and the rocky banks glisten in the wash. I fancy I hear bird call drowned out in the background, but I cannot be sure. Beyond the surging river, all is still and silent. Two large hydroelectric dams are planned for the Baker – a cacophony of concrete, steel and asphalt to tap the river’s immense natural power for city-dwelling humans thousands of kilometres away. I try to picture my surroundings submerged beneath a reservoir, imagine an access road, and the bustle of a large human workforce in this remote location . . . and fail.
Patagonia is desolate. Its very emptiness is part of its charm and it has always drawn those escaping society. Butch Cassidy and his gang sought refuge in these wastelands, as did a variety of Soviet defectors, Welsh Christians and English fortune-seekers. It’s a rainless, inhospitable place, incessantly windy and freezing cold. But the skies are vast, the austral light is incredible and the rocky desert is a palette of extraordinary colours.
Above me soar enormous black condors seeking death in the dusty grasses. In the absence of trees, other birds of prey sit on the road, leaving it until the last moment before taking off in front of my wheels. I see guanacos (a type of llama) and a black and white skunk as I drive for hour upon hour. The desert rolls on in valleys created by glaciers, and the expanse is strewn with large incongruous boulders, called ‘erratics’ because they don’t belong to this rocky ground. They were dragged down from the mountains and dumped here by ancient glaciers.
After almost a day of driving through the vast bleakness, I am relieved to see a sign of human habitation. Poplar trees struggle to protect a lone house, standing small-windowed against the chill. It is one of the region’s estancias – ranches set up by those who pioneered these lands nearly a century ago, clearing the rocks and natives to profit from a booming wool industry. Further on, I come across a bubbling carpet of sheep, herded by gauchos on horseback and their dogs. The scene looks timeless and utterly natural, and yet it’s an illusion – sheep were only introduced to the country in the late nineteenth century.
Eventually, I reach Coyhaique, capital of the Aysén region of Patagonia. In rolling hills at the foot of a basalt massif, it is a compact, ordered town whose folk live mainly by fishing and cattle ranching. For many, life is not dramatically different from that experienced by the pioneers; but graffiti around town reveals a new disquiet. ‘Patagonia Sin Represas!’ (‘Patagonia Without Dams!’) is perhaps the politest of the slogans, reflecting anger over plans for the Baker River, and for several further dams on the untamed Cuervo and Pascua rivers.
Like most hydropower, the energy would be produced by building up a head of stored water behind a dam that can be released in powerful bursts past turbines to generate electricity. To convert the relatively shallow river flows of the Baker and Pascua into deep energy stores means creating reservoirs, and together the dams would flood 6,000 hectares of land. But the biggest opposition is reserved for the accompanying electrical transmission line. Some 6,000 pylons, towering as much as eighty-five metres high, will transport the direct current 2,450 kilometres north to Santiago, Chile’s capital, and on to the energy-hungry mines in the desert beyond. The electricity line alone will require one of the world’s biggest clear-cuttings, a 120-metre-wide
