Peru’s ancient water systems can help protect communities from shortages caused by climate change


Mount Hount Huascarán, Cordillera Blanca, taken from Hauashao village. Credit: Susan Conlon

Water is essential for human life, but in many parts of the world water supplies are under threat from more extreme, less predictable weather conditions due to climate change. Nowhere is this clearer than in the Peruvian Andes, where rising temperatures and receding glaciers forewarn of imminent water scarcity for the communities that live there.

Peru holds more than 70% of the world’s tropical glaciers. Along the 180 kilometre expanse of the Cordillera Blanca (“white mountains”), more than 250,000 people depend on glaciers for a year-round supply of water. Meltwater from the glaciers supplies rivers, offering a vital supplement to rainwater so that locals can continue irrigating food crops throughout the dry season, from May to October.
But Peruvian glaciers have shrunk by 25% since 1987, and the water supply to rivers during the dry season is gradually decreasing. While national and regional governments and NGOs are responding to the threat of water scarcity with modern engineering solutions, there are growing concerns among the communities affected that such efforts are misplaced.

Modern day misfires

Take, for example, the village of Huashao. Nestled between the highest peaks of the Cordillera Blanca, Huashao is a typical farming village of the region. Glacier meltwater feeds the Yurac Uran Atma canal, which supplies irrigation water to families in Huashao. In 2011, a municipal government project transformed this canal from a rustic irrigation ditch to a modern PVC pipeline, with lock-gates to regulate the flow of water and ensure equal distribution throughout the village.
The village of Huashao. ConDevCenter/Flickr.CC BY-NC-ND
Governments and NGOs commonly promote modern measures to capture and conserve water for irrigation – for example, by lining irrigation canals with concrete, to prevent leakages. While it’s important to conserve water to safeguard food supplies, these kinds of measures have been criticised for their lack of flexibility and sensitivity to local needs.
While the pipeline in Huashao provided security and reduced the amount of time people had to devote to distributing water where it was needed, Conlon’s ongoing ethnographic research in the village found that local women were concerned about its effect on the local puquios (springs) – a valued source of irrigation and drinking water.
Noticing less water in puquios, they blamed the canal lining for stopping water from filtering into the local geology. Local communities see this process as an integral part of water distribution, but authorities often refer to it as “leakage”.
What’s more, the local people responsible for maintaining and operating the new canal found that not everything worked as planned. They were particularly worried when a problem caused water to overflow the canal walls, and blamed the design of the lock–gates.
Here, the government’s preference for modern engineering meant that it missed an opportunity to engage with traditional technologies and local knowledge. This is hardly surprising – ancient know-how has been routinely dismissed as inferior by state authorities and well-meaning (but badly briefed) NGOs. Yet traditional technologies, like the puquios, have been providing flexible ways to manage water in Huashao for hundreds of years.
In Huashao, the local people are coming to realise the limitations of modern engineering. But across the Andes, many other communities are still seduced by the promise of quick fixes offered by concrete, steel and PVC pipelines. Unfortunately, initial, costly investments of aid and expertise are rarely followed up, and since communities often lack the necessary knowledge and funds to maintain these systems, they eventually break down.

Ancient married with modern

Slowly, a push back is starting. There has been renewed interest in what society can learn from traditional irrigation systems. A recent international workshop held in Trujillo, Peru, brought together social scientists, geographers and climate scientists to discuss how to tackle issues around water use and scarcity.
It seems likely that the best solutions will be found by combining old and new knowledge, rather than dismissing one in favour of the other. For instance, parallel to the Cordillera Blanca is the Cordillera Negra (“black mountains”), which faces the Pacific Ocean. Without the benefit of glaciers, the ancient inhabitants of this area learned to harness rain water to see them through the dry season.
These pre-Colombian cultures instigated millennia-long engineering projects, resulting in large dams and reservoirs placed along the slopes of the mountains. These structures controlled water and soil erosion, feeding underground water deposits and providing water for crops and livestock.
An ancient dam in the Cordillera Negra. Kevin Lane.Author provided
Disuse over the last few centuries means that few are still functioning, but those that are, are a tribute to the ancient expertise. By contrast, modern concrete micro-dams have a functional life of 40 to 50 years, often curtailed by seismic activity to between 15 and 25 years.
Fortunately, plans are afoot to revisit these old technologies. Solutions rooted in respect for community and local knowledge, and allied to flexible modern engineering – such as better water retainment technology – are exploring ways in which we can shore-up the effectiveness of these ancient dams.
Throwing money and resources into engineering projects does not always guarantee success when trying to combat the effects of climate change and protect vulnerable communities. But the marriage of ancient and modern technologies offers promising solutions to the threat of water scarcity in Peru, and places like it all across the world.
This blog is by Cabot Institute member Dr Susan Conlon, Research Associate at the University of Bristol, and Kevin Lane, Senior Researcher in Archeology at Universidad de Buenos Airies. The article is republished from The Conversation under the Creative Commons licence. Read the original article
Dr Susan Conlon

Three history lessons to help reduce damage from earthquakes

Earthquakes don’t kill people,’ the saying goes. ‘Buildings do.’
There is truth in the adage: the majority of deaths during and just after earthquakes are due to the collapse of buildings. But the violence of great catastrophes is not confined to collapsed walls and falling roofs. Earthquakes also have broader effects on people, and the environments we live in.

The United Nations Economic and Social Commission for Asia and the Pacific (ESCAP)’s second Disaster Resilience Week starts in Bangkok on 26 August 2019. Practitioners and researchers have achieved great progress in reducing disaster risk over the past few decades, but we must do more to save lives and protect livelihoods.

Can history help?

Building against disaster

Buildings are a good, practical place to start.

Material cultures offer paths to resilience. A major example is traditional building styles that reduce the threat from seismic shaking. A building is not only a compilation of bricks and stones, but a social element that reflects the cultural life of a community. This is the powerful point made by the Kathmandu-based NGO, National Society for Earthquake Technology (NSET), in a recent report on traditional Nepalese building styles.

NSET, and others working in the field, have identified features of traditional building styles that limit damage during shaking. For example, diagonal struts distribute the load of a roof and limit damage during earthquake shaking.

Historic building with diagonal struts at Patan Durbar Square, Kathmandu, Nepal. Photo: Daniel Haines, 2017

This is important because parts of falling buildings often kill people.

Nearby, in the Himalayan kingdom of Bhutan, the royal government is investigating the earthquake-resistant features of traditional rammed-earth buildings.

An old (c. 400 years?) rammed-earth residential building near Paro, Bhutan. Photo: Daniel Haines, 2017

In fact, seismically-appropriate building styles have evolved along similar lines across a huge Eurasian arc of tectonic unrest, from Italy to Kashmir.

But in most countries, population pressure and the use of cheap, unreinforced concrete construction in growing towns and cities has crowded out traditional construction methods.

Reducing disaster risk always means weighing costs in the present against potential protection in the future. Recovering or encouraging traditional methods is potentially cheaper than enforcing modern seismic engineering.

Long-term health impacts

Focusing only on buildings, though, neglects other important aspects of large earthquakes. These shocks do not only shake buildings down, but can dramatically re-shape landscapes by causing huge landslides, changing the level of water in rivers and leading to flooding.

History shows that these changes can hurt people for months or years after the rubble of buildings have been cleared and reconstruction has begun.

For example, a giant (8.4 Mw) earthquake struck northeast India in 1897. Its epicentre was near Shillong, in the borderlands between British India and China. Luckily, the quake happened in the afternoon, so most people were out of doors. The official death toll – the number of deaths that the colonial government attributed directly to the earthquake – was around 1,500.

Yet officials also thought the poor health conditions that followed the earthquake and the substantial floods that it caused were largely responsible for a major cholera epidemic which killed 33,000 people in the Brahmaputra Valley during the same year. That is twice as many as the previous year.

From the available evidence, it is not yet clear how directly the earthquake and the cholera deaths were linked, but other examples saw similar scenarios. In 1934, another major (8.0 Mw) quake devastated parts of Nepal and North India.

This time, the official death toll in India was around 7,500, but again many more people died from related health complications over the following years. In one district in northern Bihar province, an average of 55,000 people died of fever every year over the next decade. In other areas, malaria was unusually prevalent over the same period.

Government reports held secondary effects of the earthquake responsible for the high death rate.
Events that happened long ago therefore demonstrate the complexity of earthquakes’ impacts, even on the relatively straightforward question mortality. Studying them highlights the need to focus present-day disaster responses on long-term health implications.

Of course, this says nothing of earthquakes’ less concrete, but very important, impacts on social structures, community life, governance or the economy.

History in action

In some cases, historical researchers are contributing directly to initiatives to reduce risk from natural disasters.

Hurricane Katrina showed in 2005 that low-lying New Orleans is terribly vulnerable to storm surge and flooding. Craig Colten, a historical geographer at Louisiana State University, is working with a team of scientists to find solutions by raising the height of the ground in parts of the city while adding forested wetlands on its north shore. Colten is studying analogous historical efforts in other American cities – flood-control measures in nineteenth-century Chicago and responses to hurricanes in Galveston, Texas, around 1900 – as well as examining previous proposals for creating buffers between New Orleans and the sea.

These historical examples provide evidence of what works and what does not. They also highlight the politics of decision-making that help determine whether local communities will support landscape engineering projects.

The international frameworks governing disaster risk reduction such as the Sendai Framework for Disaster Risk Reduction and the Sustainable Development Goals understandably focus on the present, not the past. Historians need to join the conversation to show practitioners that lessons from the past can help build resilience in the future.

This blog is written by Cabot Institute member Dr Daniel Haines, an environmental historian at the University of Bristol.

Dr Daniel Haines



Turning knowledge of past climate change into action for the future

Arctic sea ice: Image credit NASA

It’s more helpful to talk about the things we can do, than
the problems we have caused.

Beth Shapiro,
a molecular biologist and author of How To Clone A Mammoth, gave a hopeful
response to an audience question about the recent UN report stating that one
million species are threatened with extinction.

I arrived at the International Union for Quaternary Research (INQUA) 2019
conference, held in Dublin at the end of July, keen to learn exactly that: what
climate scientists can do to mitigate the impact of our rapidly changing
climate. INQUA brings together earth, atmosphere and ocean scientists studying
the Quaternary, a period from 2.6 million years ago to the present day. The
Quaternary has seen repeated and abrupt periods of climate change, making it
the perfect analogue for our rapidly changing future.
In the case of extinctions, if we understand how species
responded to human and environmental pressures in the past, we may be better
equipped to protect them in the present day.

Protecting plants and polar bears

from the University of Finland and colleagues are using the fossil
record to better understand how polar bears adapt to climate change. The Arctic
bears survived the Holocene thermal maximum, between 10,000 and 6,000 years
ago, when temperatures were about 2.5°C warmer than today. Although rising
temperatures and melting sea ice drove them out of Scandinavia, fossil evidence
suggests they probably found a cold refuge around northwest Greenland. This is
an encouraging indicator that polar bears could survive the 1.5°C
warming projected by the IPCC to occur sometime
between 2030 and 2052
, if it continues to increase at the current rate.
Protecting animal species means preserving habitat, so it’s
just as important to study the effects of climate change on plants. Charlotte
from the University of Southampton studies the diversity of plants
during times of abrupt climate change, using Russian lake records. Her results
show that although two thirds of Arctic plant species survived the same warm
period which forced the bears to leave Scandinavia, they too were forced to
migrate, probably moving upslope to colder areas.


If we understand how ecosystems respond to climate change,
we will be better prepared to protect them in the future. But what will future
climate change look like? Again, we can learn a lot by studying the past.

The past is the key to the future

To understand the impact of anthropogenic CO2
emissions on the climate, we must disentangle the effect of CO2 from
other factors, such as insolation (radiation from the Sun reaching the Earth’s
surface). This is the mission of Qiuzhen Yin from UC
Louvain, Belgium, who is studying the relative impact of CO2
on climate during five past warm interglacials
. Tim Shaw, from
Nanyang Technological University in Singapore, presented work on the mechanisms driving
past sea level change
. And Vachel
from the University of Utah is using charcoal as an analogue for
past fire activity
in the Rocky Mountains. By studying the pattern of fire
activity during past warm periods, we can determine which areas are most at
risk in the future.

The 2018 fire season in Colorado was one of the worst on record.

So Quaternary scientists have a lot to tell us about what
our rapidly changing planet might look like in the years to come. But how can
we translate this information into practical action? ‘Science as a human
endeavour necessarily encompasses a moral dimension’, says George Stone from Milwaukee
Area Technical College, USA. Stone’s passionate call to action is part of a
series of talks about how Quaternary climate research can be applied to
societal issues in the 21st Century.

One thing scientists can do is try to engage with
policymakers. Geoffrey
of the International Science Council
is hopeful that by partnering with INQUA and setting up collaborations with
Quaternary scientists, it can help them do that. The International Science
Council has a history of helping to integrate science into major global climate
policy such as the Paris

What can we do ourselves as scientists is to portray
scientific results in a way that is visually appealing and easy to understand,
so they are accessible to the public and to policymakers. Oliver Wilson and
colleagues from the University of Reading are a prime example, as they brought
along 3D printed giant pollen grains which they use for outreach and teaching
as part of the 3D
Pollen Project

Given that it’s easier than ever to publicise your own results,
through channels such as blogs and social media, hopefully a new generation of
Quaternary scientists will leave inspired to engage in outreach and use their
knowledge to make a difference.

This blog is written by Cabot Institute member Jen
, a PhD student in the School
of Earth Sciences
at the University of Bristol.

Jen Saxby


Climate-driven extreme weather is threatening old bridges with collapse

The recent collapse of a bridge in Grinton, North Yorkshire, raises lots of questions about how prepared we are for these sorts of risks. The bridge, which was due to be on the route of the cycling world championships in September, collapsed after a month’s worth of rain fell in just four hours, causing flash flooding.

Grinton is the latest in a series of such collapses. In 2015, first Storm Eva and then Storm Frank caused flooding which collapsed the 18th century Tadcaster bridge, also in North Yorkshire, and badly damaged the medieval-era Eamont bridge in nearby Cumbria. Floods in 2009 collapsed or severely damaged 29 bridges in Cumbria alone.

With climate change making this sort of intense rainfall more common in future, people are right to wonder whether we’ll see many more such bridge collapses. And if so – which bridges are most at risk?

In 2014 the Tour de France passed over the now-destroyed bridge near Grinton. Tim Goode/PA

We know that bridges can collapse for various reasons. Some are simply old and already crumbling. Others fall down because of defective materials or environmental processes such as flooding, corrosion or earthquakes. Bridges have even collapsed after ships crash into them.

Europe’s first major roads and bridges were built by the Romans. This infrastructure developed hugely during the industrial revolution, then much of it was rebuilt and transformed after World War II. But since then, various factors have increased the pressure on bridges and other critical structures.
For instance, when many bridges were first built, traffic mostly consisted of pedestrians, animals and carts – an insignificant load for heavy-weight bridges. Yet over the decades private cars and trucks have got bigger, heavier and faster, while the sheer number of vehicles has massively increased.

Different bridges run different risks

Engineers in many countries think that numerous bridges could have reached the end of their expected life spans (between 50-100 years). However, we do not know which bridges are most at risk. This is because there is no national database or method for identifying structures at risk. Since different types of bridges are sensitive to different failure mechanisms, having awareness of the bridge stock is the first step for an effective risk management of the assets.


Newcastle’s various bridges all have different risks. Shaun Dodds / shutterstock

In Newcastle, for example, seven bridges over the river Tyne connect the city to the town of Gateshead. These bridges vary in function (pedestrian, road and railway), material (from steel to concrete) and age (17 to 150 years old). The risk and type of failure for each bridge is therefore very different.

Intense rain will become more common

Flooding is recognised as a major threat in the UK’s National Risk Register of Civil Emergencies. And though the Met Office’s latest set of climate projections shows an increase in average rainfall in winter and a decrease in average rainfall in summer, rainfall is naturally very variable. Flooding is caused by particularly heavy rain so it is important to look at how the extremes are changing, not just the averages.

Warmer air can hold more moisture and so it is likely that we will see increases in heavy rainfall, like the rain that caused the flash floods at Grinton. High resolution climate models and observational studies also show an intensification of extreme rainfall. This all means that bridge collapse from flooding is more likely in the future.

To reduce future disasters, we need an overview of our infrastructure, including assessments of change of use, ageing and climate change. A national bridge database would enable scientists and engineers to identify and compare risks to bridges across the country, on the basis of threats from climate change.

This blog is written by Cabot Institute member Dr Maria Pregnolato, Lecturer in Civil Engineering, University of Bristol and Elizabeth Lewis, Lecturer in Computational Hydrology, Newcastle University.  This article is republished from The Conversation under a Creative Commons license. Read the original article.

Extinction Rebellion uses tactics that toppled dictators – but we live in a liberal democracy

XR protesters getting carried away. Image credit: Facundo Arrizabalaga/EPA.

After occupying parts of central London over two weeks in April, Extinction Rebellion’s (XR) summer uprising has now spread to Cardiff, Glasgow, Leeds and Bristol. All these protests involve disruption, breaking the law and activists seeking arrest.

Emotions are running high, with many objecting to the disruption. At the same time, the protests have got people and the media talking about climate change. XR clearly represents something new and unusual, which has the power to annoy or enthuse people. But what led it to adopt such disruptive tactics in its efforts to demand action on climate change?

XR is accused of being an anarchist group in a report from the right-wing think-tank Policy Exchange. To actual anarchists, that is laughable. XR strictly adheres to non-violence, seeks arrests and chants “we love you” to the police. This contrasts starkly with anarchists’ antagonistic relationship to the state and its law enforcement.

The movement claims to practice civil disobedience – but that is also a confusing label. Civil disobedience developed during the 20th century as a way of understanding and justifying law-breaking protests in liberal democracies. Much of this was in relation to the US civil rights movement. Liberal political thinkers like Hannah Arendt and John Rawls explored when and how disobedience was legitimate in a democracy.

The misfit rebellion

In some ways, XR fits with liberal civil disobedience. That disobedience should always be a last resort chimes well with XR’s claim that time is running out and traditional campaigning has proven unsuccessful. The voluntary arrests resonate with the liberal onus on open and conscientious law-breaking that accepts law enforcement.

Non-violent protest in Cardiff, July 2019. Image credit: Neil Schofield/Flickr., CC BY-NC

But on two other crucial points, XR breaks with the liberal civil disobedience tradition. For one thing, civil disobedience is generally aimed at showing the majority of the public that specific laws are unjust. XR does not seem to focus on this majority-building. It does not engage in discussion with climate change deniers, and its disruption antagonises people who do not share its fears and frustration with the inaction of governments.

Instead, XR’s tactic is to get a significant but still small part of the population to participate in disruption. The movement aims to get 3.5% of the population so incensed that they take to the streets. It does not aim to convince 51% that this is the right thing to do.

Liberal civil disobedience maintains an overall “fidelity to law”. In other words, it is considered okay to break certain unjust laws, as long as you respect the state’s laws generally. The aim is then to get the state to have better, more just, laws.

But for XR, the social contract has already been broken. The state has failed to take necessary action on climate change, thereby putting its citizens at risk. Disruption and law-breaking are therefore justified.

Talkin’ ‘bout a revolution

XR’s tactics are not based on how social movements have achieved policy change in liberal democracies. It is based on how dictatorships have been toppled. It draws directly on Erica Chenoweth and Maria Stephan’s book Why Civil Resistance Works, where they argue that non-violence is more effective than violence. The XR tactic is therefore based on how to achieve revolutions, not on how to get governments to respond to the will of the majority.

There are reasons to be sceptical about the relevance of this research, when it comes to addressing climate change. The 3.5% figure applies to such a small number of historical cases that no conclusions can be based on it. More importantly, perhaps, in most cases of regime change, not much else changes. Most in XR see saving the world as incompatible with capitalism as a system that depends on economic growth on a finite planet. Most cases of regime change on the Chenoweth and Stephan list have not resulted in abandoning capitalism – quite the opposite.

There are, however, good reasons for why XR’s radical tactics resonate with so many. People experiencing climate change through hot summers and other extreme weather events increases the sense of urgency. More importantly, perhaps, in an era of political polarisation, more extreme action becomes more likely. The trust in the state and its politicians has eroded on both the left and right across Europe. In the UK, this has been made worse by the politics of Brexit.

Law-breaking then becomes a more likely form of protest. One of XR’s spokespeople wrote on The Conversation that “the chances of … succeeding are relatively slim”. But since many in XR foresee societal breakdown as a result of climate breakdown, the cost of getting a criminal record diminishes. And if they continue to make the protests a bit of a festival, then the chances are we’ll see more disruption from Extinction Rebellion – even if it does alienate many others.
This blog is written by Cabot Institute member Oscar Berglund, Lecturer in International Public and Social Policy, University of Bristol.  This article is republished from The Conversation under a Creative Commons license. Read the original article.

Oscar Berglund