Adventures in the Anthropocene. Gaia Vince

      Opposition to the dams is based on an aesthetic, the idea of wilderness that cannot be replicated – an idea of untouched nature. Like everywhere on Earth, the influence of humans is already here in the sheep, cattle and burned forests. But in the Anthropocene, when so many wild places have been so dramatically altered, the idea of Patagonia is of increasing value to many. And while environmental activists like Peter may not hold many cards in government circles, wealthy landowners do.

      Peter drives the battered truck into the grounds of a handsome estancia. Sergio de Amesti, an agricultural engineer turned cattle farmer, manages some 3,000 hectares in the Simpson Valley, the most valuable and productive arable land in a region where 85% of the ground is rocky mountain or glaciers. The planned transmission line would run right through his land. Amesti was the regional secretary for the ministry of agriculture under Pinochet’s regime – just the sort of private-enterprise-minded character that the government might have counted on to be in favour of the dam project. But Amesti is not. ‘The main selling point of my meat is that the cattle are reared in a pure, idyllic region – uncontaminated, unpolluted, noise-free and visually pure. Huge pylons would destroy that image and lower the value of my meat and land,’ he says.

      I meet other locals in a worse predicament, including a visibly angry beekeeper, Gabriella Loshner, one of around 200 people whose homes will be flooded by the new reservoirs. Compared to other megadam projects around the world, it is a tiny population – the relatively low social cost of the Patagonian dams is something that the project’s supporters, including government ministers, repeatedly emphasise. (‘There’s no one and nothing there,’ more than one bemused minister has declared about Patagonia.) By comparison, the Three Gorges Dam in China displaced 1.2 million people and flooded thirteen cities, 140 towns and 1,350 villages. Brazil’s proposed dam at Belo Monte in the Amazon would displace 20,000 people, many of them from indigenous tribes. And hydroelectric dams planned on the Mekong in Laos would affect millions of people in the river basin and delta.

      Other Aysén residents are campaigning on behalf of non-human creatures threatened by the proposed dams, including huemal deer, native fish otters and unique cold-water corals at the river’s outlet. During the last glacial period, 10,000–20,000 years ago, the river reversed its direction of flow from the Atlantic to the Pacific, an historical quirk that infused the Baker River system with unique biodiversity. Unlike rivers to its north and south, the Baker contains an endemic population of fish, such as members of a primitive catfish genus and Odentethes hatcheri, a type of silverside.

      Dams on the Baker will prevent fish migration, and even the subtle alteration of nutrients can have far-reaching effects, says Brian Reid, an energetic American limnologist (someone that studies fresh waters), who we visit at the Patagonia Ecosystem Research Centre in Coyhaique. ‘Damming a river turns it into a lake and completely alters its function,’ he explains. Brian is interested in the river’s silica levels, which are an important component of diatoms, a major group of planktonic algae that support a large ecosystem. If the levels of silica go down compared to the levels of nitrates, another group of algae called flagellates are favoured, which are responsible for toxic oceanic ‘red tides’. Diatoms are larger than flagellates, so animals can feed on them more efficiently, making the whole system more productive.

      Brian fears that dams on the Baker River could significantly alter the silica levels downstream. ‘Damming of catchments across Europe has resulted in so much particulate trapping that it has reduced silica levels in the Baltic and Black seas. Production and efficiency of marine organisms there has gone down and it has affected fisheries.’ The head of the Baker River is a pro-glacial lake, producing significant levels of silica. ‘I row the river in a raft when I’m sampling, and you can hear the turbidity, the tiny velocities that keep everything in suspension – it sounds like a bowl of Rice Krispies,’ Brian says. If it is dammed, it will result in a warmer reservoir that would be more productive, but a loss of suspended sediments flowing to the ocean.

      No system on Earth is ever truly isolated from another, which is why the human changes we make to even small parts of the planet can have such enormous consequences. Building a hydroelectric dam hundreds of kilometres inland can affect cod numbers far out at sea. In the Anthropocene, our Earth-changing capabilities are more sophisticated than ever, but we have barely begun to comprehend the complexity of our impact. Until now, this has meant that we address each eventuality as it occurs, in a cascade of reactions to each action. But, as scientists get better at modelling the outcomes of our various interventions, we should be able to fine-tune our geoengineering to benefit people and ecosystems.

      The way that many hydrodams operate, for example, has an unnecessary impact on wetland ecosystems. So-called ‘hydropeaking’ – flooding and draining a reservoir in artificial daily pulses – can be devastating for fish. The dramatic rise and fall of water levels during dam releases – sometimes of several metres – is too extreme for plants and animals to cope with, resulting in dead zones around the shores of reservoirs. Fish that lay their eggs in the shallows among submerged tree roots, for example, may find a few hours later that those sites are high and dry with the eggs desiccated, sometimes with the loss of an entire species. Most dams use hydropeaking because it’s most profitable, releasing most energy at the peak of demand. A less damaging option is a run-of-river design which, instead of relying on a head of water to build up in a big reservoir behind a dam wall, simply allows natural river flow to drive the turbines. Run-of-river dams don’t disturb the upstream ecosystem because no reservoir is created, they don’t get silted up, and they don’t result in the abrupt upstream–downstream temperature difference you can get when a reservoir is drained from its lowest (coldest) layers. They are only suitable where a river has significant drop, which the Cuervo has, prompting campaigners to call for the dam company XSTRATA to change its dam plans there.

      But the Cuervo plan has bigger problems. The proposed dam lies directly above the Liquiñe–Ofqui fault line, on a triple point where the Nazca, South American and Antarctic tectonic plates meet. It means that there is a likelihood of a volcano or earthquake at the site, and yet there has been no study to investigate this, Peter says. In 2007, one month after XSTRATA submitted its report declaring the siting to be on a seismically inactive zone, the area experienced a massive earthquake that dislodged boulders into the fjord below, triggering a tidal wave that killed people on the opposite bank. ‘The government threw out their report,’ Peter laughs. Earthquakes have wrought considerable damage at dam sites around the world, including in April 2010, when a quake at Yushu in China’s Qinghai province killed tens of thousands of people in minutes. The Yushu reservoir, sited on a seismic zone, may actually have triggered the quake due to the weight of the water on the underlying geology. In the Anthropocene, humanity’s dam-building is shaking the Earth.

      There are other dangers too. Patagonia is one of the fastest-melting glacial regions in the world, which has already resulted in catastrophic outburst floods, debris-laden torrents carrying away entire forests. At times, these glacial floods have caused the Baker to rise by four metres and even turn around and run upstream for days at a time. ‘They are preparing to construct dams on what is probably the most unstable river system on the planet,’ Peter says, flinging his arms incredulously.

      Back in town, I visit the offices of dam company HidroAysén. Veronika, an earnest and sweet-natured woman, is adamant that the dams would rescue local people from poverty by providing much-needed employment and helping development in the region. I press her on this vague ‘development’ term, and she describes how she was one of the fortunate few who escaped from her isolated village for a year’s education in Puerto Montt, a small city further north. ‘Most people here have no choices. There are not many restaurants or shopping malls or decent education opportunities,’ she says. ‘It is very difficult even to get to the next village because the roads can be very bad and impassable, especially in winter.’ Dam-building requires improvements to the roads and surrounding infrastructure, and shops, restaurants and other services will be built to serve the workers, she reasons.

      Her colleague, Rodrigo, is also in favour of the dams because he sees them as the only viable energy option for Chile. In 2009, reliance on Argentinian gas led to disaster when a domestic crisis there created a fuel shortage and the country cut Chile off. ‘We can’t rely on another country to provide