, ,

No dam way: Will climate change kill Chile’s controversial Alto Maipo hydro project? / MSc

A Carbon Management MSc investigation, Edinburgh Geo Sciences

The small mountain refugio fell silent. It was dark outside in the Cajon del Maipo canyon. 6000metre mountains cut pitch-black silhouettes across a deep mauve sky.  Lucas, a 20 year old local kayak instructor, had just finished talking to a group of visiting university students. This morning, the dentists, engineers, doctors and geologists in training  had bussed 100km from Santiago, following the Maipo River upstream. Tonight, the nearby Alto Maipo dam construction project at the head of the valley was the subject of Lucas’ talk.

Dogged by criticism of the partiality of its environmental impact assessment –– the 531 MW Alto Maipo dam has been a highly controversial  project since its inception. Plans to syphon the electricity it will produce for mining rather than domestic use has deepened divisions. Perhaps most controversial is the substantial diversion of water flow that Alto Maipo’s 67km run-of-river tunnelling will divert from agriculture and touristic activities – essential to the communities the university students drove past this morning – before returning the water for domestic use on the outskirts of Santiago.

Polemics aside (problems perhaps left for the the social scientists, activists, NGOs and soon to be out of work kayak instructors), little attention has been given to the physical processes in the surrounding mountains that will keep the turbines churning.

Fig1. Alto Maipo hydroelectric project

The run of river project will collect water from three Andean rivers that converge in Cajon del Mapio valley to make the River Maipo, instead diverting it 39km through underground tunnels to the 275MW terminal at Central Alfalfal. Further water is collected here from the river Rio Colorado, flowing another 28km  before reaching the 267MW terminal at Central Las Lajas. Finally the water will be returned to the River Maipo river for domestic use in Santiago.  At least, that’s the plan.

Glacier melt is a key contributor of drinking water for the city of Santiago (Bodin, Rojas and Brenning, 2019). Turn on the tap, and you fill your glass with a liquid that just a few days before belonged to a millennial body of ice. Yet glacier retreat in the central Chilean Andes (in the zone of the Alto Maipo project) in the last 51 years is estimated to be as high as 20% (Magrin et al., 2014). Rising temperatures in the Andes means the zero degrees isotherm moves higher. This has two effects. Firstly, low-angled glaciers are being gobbled up. (Steeper glaciers that cross more isotherms are more resilient to rising temperatures). Secondly, rain during winter months is falling higher on the mountains where snow once accumulated. The cumulative effect of these melting phenomena in the central Chilean Andes  is the current hydrological event known as “peak water.”

Whilst water levels are currently high, ever increasing global CO2eq emissions mean we will soon have little or no long-term glacier mass left to tide us over in the summer months. Nor will there will be sufficient seasonal snow melt from the previous winter. So whilst the rivers are at peak water today, current flow rates should not be extrapolated to predict the water supply for tomorrow. Analysis of river flow across the border in neighbouring Mendoza province shows a reduction of river flow of up to 11% once the glaciers are gone (Schwank et al., 2014). Ice, and more temporal seasonal snow, are the major sources of water for Santiago (Le Quesne et al., 2009). Yet in the Alto Maipo Environmental Evaluation, this blogger could not find the words cambio climático (climate change) used once. The AES GENER Alto Maipo project leader, with their slogan energía confiable “energy you can trust” – might just need to rethink that tagline.

Additionally, Alto Maipo’s own construction project work may even be adversely affecting the glaciers they will rely on for energy generation. Dust raised from construction and drilling at the 2500m elevation construction site, as well as black carbon emissions from the lorries working at altitude, are transported by thermal air currents and can be deposited on glaciers. Like a white t-shirt in the sun, bodies of ice are usually good at reflecting heat. But by darkening the surface – even with microscopic contaminants – we are lowering the albedo of glaciers, and increasing their melt rate.

Figure 2. The blogger practices black carbon snow sampling on the approach to the 6108m Cerro Marmolejo summit sampling site. Photo ©Jon Lawn.

The silence lingered long in the packed refugio after Lucas finished speaking. With any climate and energy conundrum, the need for medium-to-long term climate mitigating renewable energy production on a national and international level; needs to be carefully weighed against consideration of immediate impact on local ecosystems, livelihoods and fresh water access. This blogger would add to these nested issues the careful consideration of the lifespan of a project, especially when its effects are so far reaching for third parties.

To break the silence, Alto Maipo needs to demonstrate clear understanding of models of changing hydrological scenarios for  future water supply and engage in candid conversation with the Cajon del Maipo community about how this affects the viability of their project.


Bodin, X., Rojas, F. and Brenning, A. (2019). Status and evolution of the cryosphere in the Andes of Santiago (Chile, 33.5°S.).

Le Quesne, C., Acuña, C., Boninsegna, J., Rivera, A. and Barichivich, J. (2009). Long-term glacier variations in the Central Andes of Argentina and Chile, inferred from historical records and tree-ring reconstructed precipitation. Palaeogeography, Palaeoclimatology, Palaeoecology, 281(3-4), pp.334-344.

Magrin, G.O., J.A. Marengo, J.-P. Boulanger, M.S. Buckeridge, E. Castellanos, G. Poveda, F.R. Scarano, and S. Vicuña, 2014: Central and South America. In: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part B: Regional Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Barros, V.R., C.B. Field, D.J. Dokken, M.D. Mastrandrea, K.J. Mach, T.E. Bilir, M. Chatterjee,
K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1499-1566.

Schwank, J., Escobar, R., Girón, G. and Morán-Tejeda, E. (2014). Modeling of the Mendoza river watershed as a tool to study climate change impacts on water availability. Environmental Science & Policy, 43, pp.91-97.

, , , , , ,

Analysis of Chile’s Decarbonisation / Reuters

SANTIAGO, June 8 (Thomson Reuters Foundation) – Chile’s new climate change plan, unveiled by President Sebastian Piñera this week, puts the host of this year’s U.N. climate conference on track to play its part in meeting globally agreed goals to limit warming of the planet, researchers said.

Continue reading

, , , , , ,

Andean plane mystery / Geographical

How do you engage people on a big scary issue like climate change?

This February filmmaker I headed into the Andes with two other British mountaineers to try and find the 1947 crashed plane Star Dust. In 2019 it’s emerging from the glacier-ice on 6570m Tupungato due to global warming. Told for the June 2019 issue of Geographical. 

“So you want to travel to the Lancastrian?” From a mid-winter Bristol suburb, my call has rung through to the Refugio Plaza military base, high in the mountains southwest of the Malbec-growing hills of Mendoza, Argentina. Sergeant Casado of the 11th Mountain Regiment listens to my request.

Continue reading




, , , , ,

Search for Star Dust / Rab

In February 2019 I led a three man 15-day expedition into the central Argentinean Andes. We were on the search for the crashed 1947 plane Star Dust. Discovered in the year 2000, nobody it seemed had been back since. Our expedition sought to reach the aircraft at the foot of 6570m Cerro Tupungato’s glacier and record any new evidence emerging from the ice due to climate change. 

Rab equipment were on board from the outset of the expedition; agreeing to outfit, sponsor and carbon offset the adventure. I wrote this piece for their blog on a cold night close to 4000m. Accompanying pictures from trip videographer Jimmy Hyland.


Link here to Rab blog (opens in new tab)


Accommodating informality in the global south

A summary of recent literature re. win-wins of low-carbon transition from informal “campamento” settlements in Chile to formal housing. Previously completed for MSc Carbon Management study at Edinburgh University, published March 5th 2018.


A prototype home in a previous “campamento” slum district in Lo Barenechea, Santiago, Chile (with energy saving and climate mitigating solar panels + space for vertical development and pedestrianised communal streets) – PH. blogsuc.cl

Cities simultaneously hold both the key as well as the door shut to effective climate change mitigation. “Account(ing) for only two per cent of the global land mass, cities…are responsible for 70 per cent of global CO2 emissions,” said Edmonton Mayor Iveson in his opening remarks to the IPCC Cities and Climate Change Conference this week in Edmonton, Alberta. Focused, well-informed climate mitigation efforts can have significant gains in these densely built environments.

Climate and social scientists had gathered to discuss the wealth of data as well as knowledge gaps that exist in current research. Inefficient spatial development; consumption trends associated with increased prosperity as well as under representation of informality in urban planning and development were key focus areas. 90% of the 2.5billion people contributing to urban growth by 2050 will be residing in cities in Asia or Africa. What therefore can be done to ensure the necessary “leapfrogging” of traditional carbon intensive development pathways for the urban poor, and a safe landing in a cooler, climate-justice-for-all pond characterised by low capital and operational carbon emissions?

The State of Play

According to a specially commissioned IPCC conference research paper about informality in the built environment, 13% of the world’s population, accounting for one billion people, live in informal settlements. Unable to access higher quality housing, the research describes these settlements as being of poor quality and “outside the rules and regulations on land-use, buildings and infrastructure and service provision.” Basic sanitation is often lacking, but, in the built environment, unpolished appearance should not be conflated with a threat to the climate. Quite the reverse: a paradox is identified by the Lancet Commission on Planetary Health between health, technology and infrastructure on the one hand; and degradation of ecosystems, increased consumption and related emissions on the other.

Informal settlements, according to the aforementioned Satterthwaite paper, typically have a low carbon intensity due to their high population density, coupled with mixed land use and narrow streets permitting only pedestrian and bicycle access. The mixed land in the Villa 31 informal settlement of Buenos Aires, whereby one building in every five holds a business, means residents don’t have to make combustion engine involved journeys to buy necessities. Lack of planning law compliance means that if extra space is needed, the city grows upwards in Villa 31 (rather than outwards), requiring less resources for construction, maintaining the efficient dense urban form.

However, upgrading of informal settlements often mark a transition towards high capital and operational carbon pathways (often due to the misheld belief that mitigative efforts in the built environment would be more expensive). Not only do these represent failures to mitigate against climate change in the built environment, but are failures to alleviate the economic burden on these formalised city dwellers. By not installing energy efficient lighting and insulation, the new “upgraded” home occupants become prisoners to continued economic stress.

Accommodating informality

The pressure to keep prices low when upgrading informal housing has, nevertheless, had a positive impact on green innovation, such as with the Jinga Materials Workshop  project in Uganda. The soil-stabilised interlocking bricks produced by the project are less carbon intensive to produce because no wood needs to be cut to fire traditional bricks.

The upgrade trend for residential campamento (slums) in Chile, has been for complete demolition and rebuilding whilst maintaining dense urban form and the narrow streets that Satterthwaite’s research describes as important for ensuring non motorised spaces for community interaction and improved air quality. An additional climate mitigation benefit of such construction comes from less carbon-intensive road surfacing required, which in turn, by reducing the amount of dark low albedo surfaces may contribute to the micro climate enjoyed by the residents of Villa 31.

Words of caution and of consumption

It would be foolish to assume, and arrogant to expect that residents of informal settlements – whose construction and mobilisation patterns currently have low carbon and climate change impacts – will continue to live by these virtues when opportunities for greater wealth and consumption patterns become available.

Responsibility for sustainable urban growth and improvements in living standards for the urban poor should instead be laid at the door of local authorities. It is their “inability or unwillingness…to plan for future urban growth,” described by Shuaib Lwasa, of Makerere University Uganda at the IPCC conference that creates, “highly ineffiecient spatial forms.” Given the economic argument for low carbon intensity development – failure by local authorities to sustainably develop informal settlements should be seen as squandering of funds available for the urban poor, as much as a failure to mitigate against climate change.

, , ,

Generation Change / Geographical

Words by Matt Maynard

Photos by Robin Loznak


My April 2019 cover story for Geographical magazine, investigated over 18months with the help of many, many inspiring youth climate activists, lawyers and researchers.

Use the zoom icon to navigate within the page. When you are ready, click the arrow to scroll to the next page.

Feature - Climate Youth v2