Category: Cities

Sea levels are rising fastest in big cities – here’s why

Sea levels are rising fastest in big cities – here’s why

By Sally Brown and Robert James Nicholls

It is well known that climate-induced sea level rise is a major threat. What is less well know is the threat of sinking land. And in many of the most populated coastal areas, the land is sinking even faster than the sea is rising.

Parts of Tokyo for instance sank by 4 metres during the 20th century, with 2 metres or more of sinking reported in Shanghai, Bangkok, and New Orleans. This process is known as subsidence. Slow subsidence happens naturally in river deltas, and it can be accelerated by the extraction of groundwater, oil or gas which causes the soil to consolidate and the surface to lose elevation.

Subsidence leads to relative sea level rise (sea level rise plus land sinking). It turns croplands salty, damages buildings, causes widespread flooding and can even mean the loss of entire coastal areas.

Subsidence can threaten flooding in low-lying coastal areas, much more so than rising sea levels, yet scientists are only just realising the global implications of the threat with respect to coastal cities.

In fact, while the average coastal area experiences relative sea level rise of less than 3mm per year, the average coastal resident experiences a rise of around 8mm to 10mm per year. This is because so many people live in deltas and especially cities on deltas that are subsiding. That’s the key finding of our new research, where we analysed how fast cities are sinking across the world and compared them with global subsidence data including less densely populated coastlines.

Map showing relative sea level rise in 23 coastal regions around the world.
When weighted by population, relative sea level rise is worst in south east Asia, followed by south and east Asia, and the southern Mediterranean. Nicholls et alCC BY-SA

Our finding reflects that people often choose to live in river deltas, floodplains and other areas that were already prone to sinking, and in doing so will further enhance subsidence. In particular, subsiding cities contain more than 150 million people in the coastal zone – that’s roughly 20% of people in the world who live by the sea. This means relative sealevel rise will have a more sudden and more severe impact than scientists had originally thought.

Here are a few of the most affected cities:


The Indonesian capital Jakarta is home to 10 million people, and is built on low-lying land next to the sea. Groundwater extraction caused the city to sink more than three metres from 1947 to 2010 and much of the city is still sinking by 10cm or more each year.

Subsidence does not occur evenly, leading to uneven risks that make urban planning difficult. Buildings are now flooded, cracks are appearing in infrastructure which is being abandoned.

Jakarta has built higher sea walls to keep up with the subsidence. But since groundwater pumping continues, this patching-up policy can only last so long before the same problems occur again. And the city needs to keep pumping since groundwater is used for drinking water. Taking water, the very thing that humans need to survive, ultimately puts people at risk from inundation.

The battle against subsidence is slowly being lost, with the government proposing in 2019 to move the capital to a purpose-built city on the island of Borneo more than 1,000km away, with subsidence being one of many reasons.


Developing rapidly in the past few decades, and now with a population of 26 million, Shanghai is another sinker. The city has maximum subsidence rates of around 2.5cm a year. Again this is mostly caused by lowering groundwater levels, in this case thanks to drainage to construct skyscrapers, metro lines and roads (for instance Metro Line 1, built in the 1990s, caused rapid subsidence).

Body of water in front of lots of skyscrapers.
Shanghai is found where the river Yangtze meets the sea. John_T / shutterstock

If no additional protection is built, by 2100 this rate of subsidence and sea level rise mean that a storm surge could flood around 15% of the city.

New Orleans

In New Orleans, centuries of embankments and ditches had effectively drained the city and sunk it, leaving about half of it below sea level.

Map of New Orleans with shaded areas below sea level.
Much of New Orleans is below sea level (red) and relies on sea walls to stay dry. The Data Center, New OrleansCC BY-SA

When Hurricane Katrina breached the levees in 2005, the city did not stand a chance. The hurricane caused at least US$40 billion (£29 billion) in damage and particularly took its toll on the city’s African American community. More than 1,570 people died across the state of Louisiana.

If the city had not subsided, damage would have been greatly reduced and lives would have been saved. Decisions that were made many decades or more ago set the path for the disasters that are seen today, and what we will see in the future.

There are no simple solutions

So what can be done? Building a sea wall or dike is one immediate solution. This of course stops the water coming in, but remember that the sea wall is sinking too, so it has to be extra large in order to be effective in the long-term. In urban areas, engineers cannot raise ground easily: that can take decades as buildings and infrastructure are renewed. There is no simple solution, and large-scale urban subsidence is largely irreversible.

Some cities have found “solutions”. Tokyo for instance managed to stop subsidence from about 1960 onwards thanks to stronger regulations on water pumping, but it cannot get rid of the overall risk as parts of city are below sea level and depend on dikes and pumps to be habitable. Indonesia’s bold proposal to move its capital city may be the ultimate solution.

Increased urbanisation especially in deltas areas and the demand for freshwater means subsidence will remain a pressing issue in the coming decades. Dealing with subsidence is complementary to dealing with climate-induced sea level rise and both need to be addressed. A combination of rising seas and sinking lands will increasingly leave coastal cities at risk.

This article was originally posted on The Conversation.
Photo by Mika Baumeister on Unsplash
Climate Resilience Needs Community Roots

Climate Resilience Needs Community Roots

Maintaining food, protection, homes for wildlife, and improved air quality is our gift to future generations. These acts of preservation are apt metaphors when thinking about the impact our actions have on the climate around us.

The trees we wander past each day provide us with many more benefits than we give them credit for. Take a walk through any city, and you’ll see that trees can sprout anywhere at any time.

The problem is that unless a city cultivates deep roots of community and citizen participation and sets the right conditions for young shoots to emerge, or tends to plants as they mature, then the city will not develop a dense, strengthened canopy for sustained climate futures.

Just like the tree, cities and regions also need to create spaces for climate resilience to take root.

Inclusive spaces, where opinions from a diverse range of actors can be meaningfully heard, and complex challenges that governments cannot tackle alone can be collectively addressed.

Most importantly, cities and regions need to create environments with strong collaboration roots and where citizen participation can bloom and, just like the trees, improve a city’s long-term climate resilience, creating a healthy, clean future for everyone.

However, the problem is that sometimes you need to take a pretty long walk, through several cities, to find such well-rooted collaboration.

A new Democratic Climate Model highlights how democratic principles can lead cities and regions to respond differently to climate change.

The Model is underpinned by meaningful participation and legitimised by continuous community consent. A vital feature of the Model is that it strengthens democratic institutions in the long term through citizen participation.

Herein lies the democratic climate conundrum.

Despite this type of famed citizen participation, it is currently on a distant and abstract level, with very few citizens involved.

Participation is still a very long, long walk away from most interested citizens and their daily lives.

The UN and the EU are famed for leading the way to include citizen voices during climate negotiations.

From the 1992 Rio Declaration to the 2020 European Climate Pact as part of the European Green Deal, citizens have had some form of a voice in climate-related decision-making.

What about involvement closer to home?

The good news is that cities and regions are mostly aware of the importance of addressing climate change. City leaders are starting to reimagine city life without chronic congestion, polluting buildings, and shrinking green spaces.

The bad news is that too many cities and regions have their efforts hampered by low-levels of citizen participation.

Dialogue, however, is fading away, critically when residents need to adjust to new climate laws, and more importantly, have a say in shaping legislation.

The call for greater citizen participation in climate decision-making processes is far from a new suggestion.

What we see now, though, is a massive disconnect between the enthusiasm of climate-opinionated residents and the engagement of such communities in participatory processes that can create more climate-friendly ways of living, working, and playing in a city.

Why is there a disconnect?

In short, it seems that the old ways of working, through narrow dialogues, a homogeneity of voices, and technocratic, short-term solution-based thinking, are stunting the process.

Citizens are fatigued by being told what to do by those in power and want agency and ownership over decisions that impact their quality of life. They wish to do away with top-down decisions where citizen participation is an afterthought or box to tick.

Cities and regions are coming around to this idea and want increased community acceptance and support for climate measures. They are also aware that investments in this process will yield new insights based on lived experience, local knowledge, and expertise. However, the road is not easy.

Meaningful participation requires the transformation of the usual systems to create lasting structures that address complex challenges, such as climate change.

Citizen participation for climate resilience is needed now.

EIT Climate-KIC Healthy, Clean Cities Deep Demonstrations

Along with several design partners, Democratic Society took up the challenge of inspiring cities to experiment with new approaches to citizen participation as part of the EIT Climate-KIC Healthy, Clean Cities Deep Demonstrations project consortium.

Democratic Society also wanted to use this experience to develop a scalable model that could be experimented with in any city, anywhere.

The project brought together experts from financing, innovation, carbon accounting, and citizen participation to design and conduct strategic work programmes with cities.

Crucially, Democratic Society also employed Local Connectors in each city, skilled practitioners with expertise in policy and civic engagement, social innovation and design for sustainability, and locals in the cities they worked in.

They collaborated with city leaders and consortium design partners and joined the dots between the diverse actors involved. They worked towards a good transition that included government bodies, civil society organisations, grassroots groups, journalists, and businesses.

The locations for these programmes? The 14 European cities of Amsterdam, Edinburgh, Kraków, Križevci, Leuven, Madrid, Malmö, Maribor, Milano, Niš, Orléans, Sarajevo, Skopje and Vienna.

With the facilitation in place, the Deep Demonstrations were then designed to achieve systematic change in a range of climate resilience priority areas.

These were mobility, logistics, housing, building environment, waste and the circular economy, energy, and urban greening.

The participatory elements of the Deep Demonstrations as led by Democratic Society utilised the concepts of community placemaking conversations, hyperlocal governance, climate assemblies, opportunities for co-production and co-ownership, different models of collaboration between city governments and citizens, and embedding participation in transition governance. 

Learnings about meaningful collaboration

Looking back at 18 months of reimagining quality of life in 14 European cities, a lot is to be learnt.

One message is clear: city leaders can better address climate challenges by embedding democratic principles, such as collaboration, power-sharing, and transparency in their climate resilience work.

More in-depth and broader citizen participation can help to reimagine life in cities and generate buy-in for policies.

Introducing our Climate Democratic Model

Here we present the first iteration of a Democratic Climate Model based on our learnings from the Deep Demonstrations project. We would also like to invite you to provide your feedback and engage us in a discussion.

The Model is illustrated through the tree analogy. While trees come from seeds, the seeds themselves do not contain the resources needed to grow them.

Instead, the seeds that sprout from the conditions around them and the roots that provide the tree with a sound footing to draw in nutrients create stability and grow towards the surface.

The nodes of connectivity between the roots broaden the possibilities of a nurtured and nourished canopy above. Just like the tree, climate resilience needs deep roots in communities that policies serve.

The Model features three parts: Rooted vs. Weak collaboration, The City Canopy, and an Actor Framework.

Rooted vs. Weak Collaboration

Rooted vs. Weak Collaboration visualises the degree to which strong or weak collaboration roots unlock climate resilience in cities, now and for future generations.

Rooted collaboration

‘Rooted collaboration’ shows the benefits of cultivating deep roots of community and citizen participation so that cities develop a dense, strengthened canopy for sustained climate futures.

Weak collaboration

Conversely, ‘Weak collaboration’ is what happens without firm roots, where lack of citizen participation risks collapsing the city into a non-inclusive and non-sustainable climate future.

The City Canopy

The ‘City Canopy’ is a tool for mapping the scales of climate resilience developed through rooted collaboration.

In this model, the denser the canopy that covers a city, the more likely its structures and processes support rooted collaboration, shifting the city or region towards strengthened citizen participation and climate policy governance that will stand the test of time.

Our findings across the 14 Deep Demonstrations cities suggested that four elements are central to ensuring a city can progress towards climate resilience: 1) Diversity of actors; 2) Participatory culture; 3) Subject matter expertise; 4) Resources. Each of these elements has several characteristics that we use to calculate a City’s Canopy.

The presence of these four elements are mapped to three layers: Foundational, mobilising factorsEmerging shifts, and the scale of Future possibilities in the city to increase the density of their canopy for climate resilience.

Actor Framework

The Actor Framework helps us explain the types of actors involved in the Democratic Climate Model, what roles they play, and how their roles must evolve to bring about just and sustainable climate futures. Types of actors include artists, activists, researchers, grassroots groups, civil society, companies, governments, and journalists.

In every city and region, different actors participate to different degrees. How much and how actors come together has a bearing on the degree of rooted collaboration for climate resilience. We also use the actor framework to calculate the diversity of actors element in the City Canopy.

Like all parts of the Democratic Climate Model, this framework will continue to evolve. We invite your feedback.

Field notes

Let us take a closer look at how the Deep Demonstrations played out in Orléans Métropole, France. This city saw the opportunity to bolster its participatory culture and question old ways of working.

Read the Orléans Métropole case study

The vision

The vision for our Democratic Climate Model is that it can be used to inspire more collaborative engagement, more profound thought about who and what we value, and embed democratic principles for just climate transitions in thousands of cities and regions.

The ultimate goal is for an interconnected, international network of climate-resilient cities and regions – liveable areas, where citizens are engaged and live their best lives within vibrant, inclusive, and socially-just communities.

If there is one message you should take away from this article it is this:

Yes, cities and regions need to find new ways to involve citizens in climate decision-making. Still, they cannot do this without city leaders, funders, and active citizens in the climate space, reflecting on how they need to act differently.

The Democratic Society can help with that.

Democratic Society, through strengthening governance, participation, and civil society, can help you make the best use of the Model outlined in this article.

Read the original article here.

Poorest people will suffer worst from cities’ heat

Poorest people will suffer worst from cities’ heat

By Tim Radford

As ever, the poorest people will most feel the heat in a hotter world. But a green growth initiative could help them.

As the summer thermometer soars, and the cities of the US Southwest are caught up in extremes of heat, the poorest people who live in the least prosperous districts may find their streets as much as 3°C hotter than those of the wealthiest 10%.

And in Los Angeles, one of the richest cities in one of the richest states of the world’s richest nation, citizens in the most heavily Latin-American districts could be as much as 3.7°C hotter than their white, well-heeled neighbours.

Excess heat is linked to heat stroke, exhaustion, respiratory and cardiovascular problems and of course death: one US group has identified 27 ways in which heat can kill, and several sets of researchers have independently established that potentially lethal heat waves are becoming more likelymore extreme and more widespread.

Californian geographers report in the International Journal of Environmental Research and Public Health that they mapped summer temperatures in 20 urban centres in California, Nevada, Utah, Arizona, Colorado, New Mexico and Texas.

“The study provides strong new evidence of climate impact disparities affecting disadvantaged communities”

They looked at the data for median household income, and for ethnic origin, to identify the ratio of Black, Latin and Asian populations in each.

They also took into account education levels. And then they looked at satellite data for radiant and atmospheric temperatures on the warmest summer days and nights.

The greatest disparities in street temperature were in California. But on average the poorest 10% of neighbourhoods in a conurbation would be 2.2°C hotter than the wealthiest 10% both on average summer days and during extremes of heat.

There is a term for this: the inner city becomes a heat island. As global temperatures rise, crowded cities become increasingly inhospitable. Paved streets and car parks absorb and retain the sun’s radiation.

Ending ‘thermal inequity’

The suburbs and the high-amenity residential districts will have tree-lined streets, private gardens, parks, flower displays, lawns and even fountains or pools, all to help lower the local temperatures.

Using the constrained language favoured by science journals, the authors write: “The implication would be that programs to increase vegetation within disadvantaged neighborhoods and reduce or lighten pavements and rooftops could help reduce thermal disparities between neighborhoods of different socio-economic characteristics.”

The researchers can hardly have been surprised by their own results: a look at published research had shown them that other groups have found evidence of what they call “thermal inequity” in Hong Kong, New York and Chicago, as well as in Santiago, Chile and in the crowded cities of Britain’s West Midlands.

“The study provides strong new evidence of climate impact disparities affecting disadvantaged communities, and of the need for proactive steps to reduce those risks,” said John Dialesandro, of the department of human ecology at the University of California Davis, who led the research. “There is a strong need for state and local governments to take action.” − Climate News Network

This article was originally posted on The Climate News Network.
Cover image by bantersnaps on Unsplash.
Fragile cities are being inundated with people fleeing the impacts of climate change. How can they cope?

Fragile cities are being inundated with people fleeing the impacts of climate change. How can they cope?

By Ambika Chawla

When the rains never arrived in the East African nation of Somalia in 2016, nor in 2017, hundreds of thousands of rural residents were forced to abandon their lands and livelihoods due to one of the most severe droughts in decades. Then, in 2019, from September to December, heavy rains led to severe flooding there, displacing hundreds of thousands of people from their homes in rural areas and towns in the districts of Belet Weyne, Baardheere and Berdale.

These climate migrants traversed barren and dusty landscapes, or traveled through torrential rains, in search of food and shelter. Many ended up in refugee camps in urban areas such as Badbaado, a sea of makeshift tents on the outskirts of Mogadishu that is now home to tens of thousands of internally displaced persons.

The challenges they face are profound, says Ben Mbaura, national emergency response and disaster risk reduction coordinator at the International Organization for Migration (IOM), including inter clan conflict, poor sanitation, limited education and insufficient access to food. On top of that, many “do not have the necessary skills to match labor market needs, which also results in high levels of unemployment and exclusion,” Mbaura notes.

The response to internal displacement like this has long been to provide emergency or short-term assistance. In recent years, however, with so many internally displaced persons living in protracted displacement, humanitarian organizations have increasingly recognized the need to empower them to move toward greater self-reliance. As a result, in 2016 the U.N. and the government of Somalia created the Durable Solutions Initiative (DSI) as a way to introduce long-term solutions for internally displaced persons in Somalia. The DSI gives these people a voice in decision-making processes that shape their future — and offers a model for other cities that are, or soon will be, in similar circumstances.

Fragile Cities

Every year, millions of people around the world are forced to abandon their lands, livelihoods and communities due to the effects of climate change. And the rate of climate-induced migration is increasing — with most taking place in the form of rural-urban migration within countries.

According to a recent World Bank report, “internal climate migrants” could number more than 143 million by 2050, mainly in sub-Saharan Africa, Latin America and South Asia. If the past is any indication, most will be forced from their homes by extreme weather events. Others will move from rural areas to cities due to slow-onset climate-related events, such as desertification.

Humanitarian experts predict that the current trajectory of climate change will displace millions of people in the Global South. Source: Kanta et al. 2018. Groundswell: Preparing for Internal Climate Migration. Washington, D.C.: The World Bank.

Pablo Escribano, a specialist on migration and climate change in Latin America for the IOM, says this migration will create “urban hot spots” where displaced persons converge in search of shelter, food and jobs.

Climate migrants who arrive in cities are likely to move to informal settlements, and many of these hot spots will occur in rapidly expanding cities in low- and middle-income countries with weak governance and limited capacities to provide social services and infrastructure.

“In Asia, recent estimates of the increase in sea-level rise have strong implications for cities like Jakarta, Bangkok and Dhaka,” Escribano says.

In Latin America, he says, Rio de Janeiro, Lima, La Paz and Mexico City will experience migration pressure from sea-level rise, melting glaciers and other climate-change effects. “Fast-growing cities in Africa, such as Lagos, Luanda and Kinshasa are also considered to be city hot spots,” he adds.

Urban development expert Robert Muggah has dubbed these urban settings as “fragile cities.” As the co-founder and research and innovation director of the think tank Igarapé Institute in Brazil, Muggah developed 11 indicators that determine urban fragility, including crime, inequality, lack of access to services and climate change threats.

Ani Dasgupta, global director for the Ross Center for Sustainable Cities at the World Resources Institute (WRI), says fast-growing cities face multiple threats that increase the vulnerability of new arrivals.

“As cities expand, many municipal governments are overburdened. They are not able to keep up with increasing demand for basic services, like housing, jobs, electricity and transport,” he says. “The climate crisis is an additional challenge on top of this. Flooding, heat waves, water shortages and more powerful storms tend to affect new migrants and already vulnerable populations most severely.”

Move Toward Self-Reliance

The goal of the DSI is to strengthen the ability of government at all levels — local, state and federal — to help internally displaced persons integrate into society. It has mobilized funding from donors such as the World Bank, U.N. agencies and the Peacebuilding Fund (the U.N.’s financial resource for supporting peace in areas experiencing or at risk of conflict) to support initiatives that allow internally displaced persons to present their ideas for community infrastructure projects along with strategies to become self-reliant.

Teresa Del Ministro, the DSI coordinator for Somalia, says the DSI is a response to a growing global awareness of the limitations of traditional humanitarian approaches to deal effectively with internally displaced persons. “With that trend increasing worldwide, it appeared that multi-stakeholder partnerships are needed at all levels,” she says.

The DSI is considered particularly innovative because it lets internally displaced persons articulate the kinds of solutions they need to move toward self-reliance.

“A participatory, locally owned approach is one of the programming principles for the DSI,” says Isabelle Peter, the DSI’s coordination officer.

One example is the Midnimo I project supported by the Peacebuilding Fund with the IOM and UN-Habitat as partners.

With support from Midnimo I (“midnomo” means “unity” in Somali), climate migrants and other displaced persons in southern and central Somalia met with representatives of their host communities, along with city and national government officials, to develop creative solutions to the many challenges they face. Among other things, the initiative sought to help communities define and drive their own recovery — most prominently through community action plans (CAPs), documents that lay out local priorities for community-driven recovery.

As part of Midnimo I, the IOM trained Somali government representatives to engage displaced persons in visioning exercises to help them articulate their short-term needs and present ideas on strategies to move toward greater self-reliance.

Ali Hussein camp on the outskirts of Burao, Somaliland, is home to numerous families displaced by conflict and drought. Photo courtesy of Oxfam East Africa from Wikimedia, licensed under CC BY 2.0

Midnimo I was implemented in the cities of Kismayo and Baidoa, home to more than 450,000 internally displaced persons.

“Together they would come up with priorities for infrastructure investments or other types of investments. If a project didn’t have funding for these priorities, the government would convene other actors and ask for their support,” says Del Ministro.

According to an evaluation report by the IOM, the Midnimo I project created short-term employment opportunities, led to the construction of community infrastructure projects and contributed to the establishment of a land commission and to improved relations between authorities and displaced communities. Nearly 350,000 people directly benefited from the Midnimo I project as a result of constructing or upgrading community-prioritized schools, hospitals, water sources, police stations, prisons, airports and more, according to the IOM’s Mbaura.

The DSI in Ethiopia

The DSI also has been implemented in Ethiopia, where a drought that began in 2015 left millions dependent upon emergency food aid. The government of Ethiopia, with support from U.N. agencies, governments, donor agencies and non-governmental organizations, launched its own DSI in December 2019. As in Somalia, the focus is on long-term self-reliance.

“The scale of the displacement surprised many in the international community, and there was recognition that collectively we needed to support Ethiopia,” says Hélène Harroff Atrafi, the DSI coordinator in the U.N. Resident Coordinator’s Office. “In doing so, we looked at international good practices, including in neighboring Somalia.”

At this point, the governance structure for the DSI is being established with the government of Ethiopia in the lead. “We have agreed on the vision forward, we have brought together all of the partners who want to work together. Now the operational rollout must begin,” says Atrafi.

In the Somali region, one of 10 regions of Ethiopia, the DSI is now at the stage of detailing the options that internally displaced families have: urban and rural relocation, return to the location of origin, and potential integration in the settlements where the displaced individuals currently reside.

Abdi Koracle is one of countless Ethiopians who have been forced by conflict or climate to migrate to fragile cities. Photo courtesy of Pablo Ferrández | Internal Displacement Monitoring Centre

According to the World Bank report “Groundswell: Preparing for Internal Climate Migration,” the number of climate migrants in Ethiopia could close to triple by 2050, with Addis Ababa set to become an urban hot spot for climate induced migration. Smaller cities, such as Jigjiga and Deri Dawa, are also expected to receive increasing waves of climate migrants.

In February 2020, Ethiopia ratified the African Union Convention for the Protection and Assistance of Internally Displaced Persons (IDPs) in Africa, a legally binding instrument for protecting internally displaced persons in Africa. There is hope this will bring greater awareness about the need to support innovative, participatory initiatives for internally displaced persons there.

Looking Forward

Around the world, fragile city governments can partner with international humanitarian organizations, NGOs, research institutions, the private sector, U.N. agencies and other city governments to strengthen their capacities to tackle challenges at the intersection of urbanization, climate and migration.

For the Internal Displacement Monitoring Center (IDMC), a think tank based in Geneva, multi-stakeholder partnerships play a crucial role in gathering information about internally displaced persons.

“We start with the people affected — internally displaced persons and host communities — and from there, we build up the agenda, collaborating with national governments, U.N. agencies, NGOs, academia and research centers,” says Pablo Ferrández, a research associate with the IDMC.

Andrew Fuys, senior director for global migration at the nonprofit Church World Service, says that one of the priorities for research is to identify how the risks climate migrants face are similar to, or differ from, those of other internally displaced persons in cities so that organizations can provide the appropriate services for climate migrants.

This article was originally posted on Ensia.
Cover photo by ssadikgulec on
How climate change threatens a Peruvian city with ‘glacial flood’

How climate change threatens a Peruvian city with ‘glacial flood’

By Rupert Stuart-Smith and Gerard Roe

The worldwide retreat of mountain glaciers is one of the most visible impacts of climate change. In the wake of receding glaciers, thousands of lakes have formed and expanded. These lakes threaten the communities living below them with tsunami-like waves known as “glacial lake outburst floods”.

One such lake, Palcacocha, sits high in the Peruvian Andes and is notorious as one of the world’s greatest flood risks. It threatens tens of thousands of people living downstream.

This looming catastrophe has raised questions about the role of climate change in creating this flood hazard.

Our new study, published in Nature Geoscience, is the first to assess the role of climate change in changing an outburst flood hazard. By establishing this link, our research provides new evidence for an ongoing legal case brought against RWE, which aims to hold the German utility firm responsible for its historical contribution to climate change.


As the Palcaraju glacier in the Andes has melted, Lake Palcacocha has expanded rapidly – approximately 34-fold by volume since 1990 (pdf). The meltwater is gradually filling the valley vacated by the retreating glacier.

Labelled by the media as a “deadly flood timebomb”, the risk to downstream communities persists despite the efforts of local authorities to drain and dam the lake.

The view that Lake Palcacocha poses a serious flood risk is well supported by scientific research. These studies show that were an outburst to occur – most likely triggered by an avalanche – flood waters would reach Huaraz, a downstream city of 120,000 people.

Census data suggests that 22,500 inhabitants live in the path of a potential flood within 80 minutes of an outburst.

Palcaraju is just one of thousands of glaciers around the world that are retreating as the climate warms. The characteristics of each individual glacier, along with the local climate, will determine how it responds to Earth’s rising temperatures.

In our study, we accounted for these factors and considered all steps of the causal chain – from emissions of greenhouse gases to the present-day flood risk.

Quantifying the role of climate change

To assess the human influence on the flood hazard from Lake Palcacocha we considered in turn: 

  1. The role of greenhouse-gas emissions in the change in temperature around Palcaraju glacier.
  2. The influence of this change in temperature on the retreat of the glacier.
  3. The impact of the resultant expansion of Lake Palcacocha on the flood hazard to which the people of Huaraz are exposed.

Previous research has established that virtually all global temperature rise since the mid-19th century is the result of greenhouse-gas and aerosol emissions from human activity. Given spatial variation in temperature trends, we first tested whether this relationship between human influence and warming held true in the region around Palcaraju glacier.

Applying methods used in the Intergovernmental Panel on Climate Change (IPCC) special report of global warming of 1.5C, we established that 95% of the observed temperature change around the glacier is the result of human-caused climate change.

We then considered what role this temperature change has played in the retreat of Palcaraju glacier and, therefore, in the expansion of Lake Palcacocha.

Our results show that the observed retreat would not have happened without human-caused warming. Further, our central estimate is that 100% of the retreat is due to the temperature trend since 1850. In other words, in the absence of climate change, it is as likely that the glacier would have lengthened as it is that it would have retreated.

Having established the role of climate change in the dramatic expansion of Lake Palcacocha, we considered how this has changed the outburst flood threat posed by the lake.

Applying two independent “outburst flood hazard” ranking indices, the smaller lake of the 19th century is categorised as having a “medium” hazard. Subsequent growth has raised the lake to the highest hazard level. In response, local authorities have been compelled to implement hazard mitigation measures (pdf).

These findings establish a direct link between greenhouse gas emissions and the growing flood hazard to which Huaraz is exposed. The need to implement protective measures now –  as well as any potential damages caused by flooding in future – can, therefore, be linked to climate change for the first time.

Early climate change impacts

The people of Huaraz have experienced the deadly threat posed by Lake Palcacocha once before. In 1941, a devastating outburst flood from the same lake destroyed one-third of the city, causing at least 1,800 fatalities and possibly as many as 4,000.

Our research shows that the emergence of human-induced climate change in the early 20th century initiated the retreat of Palcaraju glacier and the expansion of Lake Palcacocha, giving rise to the dangerous setting depicted in the photographs.

Our results indicate, therefore, that this mid-20th century event was one of the earliest fatal impacts of climate change to have been identified.

Setting a legal precedent?

Our findings offer new evidence relating to an ongoing lawsuit in the German courts.

In this case, Saúl Luciano Lliuya, a farmer and mountain guide from Huaraz, sued RWE – a German energy utility and Europe’s largest carbon dioxide emitter – seeking compensation for a portion of the costs of measures to reduce the flood risk from Lake Palcacocha.

The lawsuit argues that RWE is liable for part of the costs of building flood defences, in proportion to their contribution to historical greenhouse gas emissions. As such, the case hinges on the existence of a causal relationship between climate change and the need to build flood defences.

The lawsuit is now in an evidence-gathering phase, in which scientific evidence about this causal relationship may be considered.

Lawyers have previously heralded climate change attribution science as a fundamental source of evidence for climate-related lawsuits.

And, although evidence from attribution research has not yet entered widespread use in climate lawsuits, climate scientists now possess the tools to provide evidence about the role of greenhouse gas emissions in causing specific impacts.

For example, scientists previously published a study investigating the role of climate change in Japan’s 2018 summer heatwave. The research found that a heatwave as intense as that of summer 2018, in which over 1,000 people died, could not have occurred without climate change

Such studies add to the growing body of evidence that lawyers have at their disposal on which to base legal claims for compensation.

Ongoing threat

Glacial lake outburst floods are already a major hazard as mountain areas. The ongoing retreat of glaciers will threaten growing numbers of communities. Our findings provide clear evidence that the threat to life from Lake Palcacocha is a direct consequence of human-caused climate change.

Even as the impacts of climate change continue to accumulate globally, there remains no comprehensive assessment of what the climate change impacts experienced to date are.

Understanding which events are the consequence of human activity has assumed growing significance and research on this topic may inform litigators and the courts, support policymakers in prioritising adaptation measures, and refine estimates of the economic impacts of climate change.

This article was originally published on The Carbon Brief. TCC BY-NC-ND 4.0

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NUS researchers develop new urban planning GIS tool to improve urban climate resilience

NUS researchers develop new urban planning GIS tool to improve urban climate resilience

Singapore has warmed notably since the mid-1970s when rapid urbanisation took place, at a rate of 0.25 degrees Celsius per decade according to the Meteorological Service Singapore. The rate is higher than the global average rate of 0.17 degree Celsius per decade since 1970, based on data from the United Nations Intergovernmental Panel on Climate Change. If the current urban development approach remains unchanged, local warming will lead to a rise in electricity demand for cooling and the risk of residents suffering from heat stress.

To help Singapore stay cool and improve urban climate resilience, Presidential Young Professor Dr Yuan Chao from the Department of Architecture at the NUS School of Design and Environment led a team to examine the heat balance in the street canyon – where the street is flanked by buildings on both sides – and developed a user-friendly Geographic Information System (GIS) tool to estimate the impact of urban planning on anthropogenic heat dispersion.

“The weak removal of anthropogenic heat is caused by stagnated airflow at urban areas. It is crucial to investigate the effect of urban morphology on anthropogenic heat dispersion to make high-density cities more resilient to future challenges such as an intensive urban heat island effect,” Dr Yuan explained.

In their findings published in the scientific journal Energy and Buildings, Dr Yuan Chao, Dr Mei Shuojun, Dr He Wenhui and Ms Zhang Liqing investigated the transient street air warming procedure and developed a practical GIS-based model to estimate how much and how fast the air temperature will be increased by anthropogenic heat.

By applying this novel model, the impact of urban morphology on anthropogenic heat dispersion was mapped. The dynamic air temperature increment caused by daily heat emissions was visualised in residential areas of Singapore. The maximum temperature increment with normal wind conditions could be about 0.45 degrees Celsius, which has a significant impact on both thermal comfort and public health.

Dr Yuan observed, “The air temperature increment in residential areas could be even higher in the future due to rapid global warming and urban development. It could increase the risk of residents in tropical cities suffering from more frequent and intensive long-term heat stress and short-term heatwaves.”

Feasible planning tool to deal with future uncertainty

The development of the new GIS-based analytical model starts from urban planning indices, and thus avoids the complicated fluid dynamics calculation used in Computational Fluid Dynamics (CFD) simulation and wind tunnel, both of which are time-consuming especially for modelling at the urban scale. This model is a cheaper and faster alternative for urban planners to estimate the impact of urban planning and design on anthropogenic heat dispersion.

“Due to the huge uncertainty caused by urbanisation and global warming, the new GIS-based analytical model is a feasible tool to deal with numerous microclimate scenarios to help Singapore stay cool,” shared Dr Yuan.

Beyond applications in Singapore, this practical model can be easily adopted in cities overseas. By seamlessly connecting this model with global and regional scale models, city-level findings can also be used to tackle anthropogenic heat problems globally. As the next step, the team will explore collaborating with researchers working on global and regional scale models. Air pollution as another important urban climate issue will also be integrated into this GIS tool.

The GIS-based model is developed in collaboration with the Future Resilient Systems project at the Singapore-ETH Centre (SEC) that is supported by the National Research Foundation, Prime Minister’s Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) programme, as well as the National Supercomputing Centre Singapore.

Read the original story here.
Resilient Urban Infrastructure – Helping Cities Find the Right Blend of Finance

Resilient Urban Infrastructure – Helping Cities Find the Right Blend of Finance

By Max Lohmann

There is a wealth of options to consider when financing urban infrastructure. Some of these include but are not limited to: public-private partnership models; user fees or other domestically mobilized resources; loans from commercial or multilateral development banks; grants from facilities like the Green Climate Fund; or contributions from local businesses. Raising large investment volumes often requires a blend of these options. To build a financing model, cities need the capacity to identify and evaluate different sources of finance as well as present a convincing business case to financing partners. Especially for private investors, incentives do the trick––ranging from clear revenue streams to corporate social responsibility or insurance against the effects of extreme weather events.

One of the key challenges faced by cities is to develop a business case for projects that lack a clear revenue stream. This is usually the case with infrastructure projects addressing climate resilience, where the ideal financing blend may be hidden within the interests of complex stakeholder landscapes. The C40 Cities Finance Facility (CFF) has partnered with eThekwini Municipality (Durban) in South Africa to assist the city to overcome this challenge.

The CFF currently works with 17 cities in Asia, Africa, and Latin America, to prepare and finance infrastructure projects that build climate resilience, reduce emissions in public transport, or strengthen renewable energy generation. With a contribution by USAID, the CFF was able to strengthen its focus on climate resilience. In addition to projects in Dar es Salaam and Dakar, the CFF is working with the eThekwini Municipality in Durban, South Africa, on a water and waste management project.

Over the past decade, floods in eThekwini Municipality have increased in frequency and intensity, resulting in the loss of lives and damage to infrastructure. The flood risk in some of the city’s most vulnerable and disadvantaged communities is exacerbated by an increase in solid waste creation and the limited capacity for its collection and disposal. In response to this situation, the city piloted the ‘Sihlanzimvelo’ stream cleaning program in 2017. The initiative has reduced flooding—as well as crime and diseases—and removed waste and alien vegetation from 300 km of the city’s rivers and streams. Despite its success, the programme could not be scaled up due to a shortage of financial resources.

With CFF support, the city was able to engage local communities, businesses and NGOs to expand the pilot into a city-wide Transformative River Management Programme (TRMP). By aligning interests of local stakeholders, the program will create hundreds of community co-operatives to clean and maintain riverbeds. As per the current project scope, these cooperatives will employ up to 4,000 people. To finance the annual operational expenditure, the city has developed a cost recovery approach. By forecasting disaster relief and repair costs avoided through the TRMP, this system captures savings generated by investments in flood management programs. As such, the business case allows the city to establish an annual budget line to cover a large share of recurring operating costs. Contributions from residents and local business—in the form of river management fees—will complement these funds. Hard infrastructure elements, such as drainage systems, elevated bridges, and riverbank reinforcements, will be financed through debt and grants with the help of development banks and grant facilities. With this model, the 300 km pilot can be upscaled to 3,000 km of city rivers, with a potential for further extension up to 7,400 km in the medium term.

Aside from the technical preparation and financial modelling, the CFF has also worked with Durban to strengthen the municipality’s knowledge of topics such as transformative adaptation and financing resilience projects. Additionally, an intensive knowledge exchange has helped leading municipalities in the Central Kwa-Zulu-Natal Climate Change Compact, an effective exchange platform of municipalities across the South African province of Kwa-Zulu-Natal, to produce their own TRMPs. This will enable cities across the region to make the case for investments in ecological infrastructure to strengthen urban resilience.

In tandem with USAID, the CFF is also supported by the German Ministry for Economic Cooperation and Development (BMZ), the UK Government and the Children’s Investment Fund Foundation. Over the last year, mobility projects in Mexico City and Bogotá have been successfully linked to finance, leveraging an investment volume of $210 million and reducing 640,000 tons of CO2 emissions by 2050. In 2021, the CFF will enter its next phase of operations, aiming to further upscale its support to cities interested in resilient climate action projects.

This article was originally posted on Climate Links.
Cover photo by Tran Phu on Unsplash.
UCCRTF city of Sialkot amongst those hit by new “smart lockdown strategy” to fight COVID-19

UCCRTF city of Sialkot amongst those hit by new “smart lockdown strategy” to fight COVID-19

By Tassadaq Shah

COVID-19 cases have been rapidly increasing in Pakistani cities in recent weeks. The rate of infection became so high that, on June 13th, Prime Minister, Imran Khan, announced that a “smart lockdown” strategy would be imposed on certain hot spots across the country.

Khan emphasized that the country’s precarious economic situation, meant that a nationwide lockdown was impossible. The smart lockdown strategy aims to curb the spread of the coronavirus and helps to balance the lives of citizens with their livelihoods. The strategy is designed to contain the disease in high risk areas which are reporting large numbers of coronavirus cases negating the need for countrywide restrictions.

The National Command and Operation Centre (NCOC) undertook a comprehensive review of potential COVID-19 clusters and, on June 15, identified 20 cities in the country that were “high risk areas”, which are reporting large numbers of COVID-19 cases. These areas were then targeted for limited locality-based. The cities that were identified as having a “likely increase in speed of infection” required restrictive measures for containment of COVID-19. A testing, tracing and quarantining (TTQ) strategy is also being employed as part of the containment strategy.

Starting from June 16, smart lockdowns were implemented through provincially issued orders and regulations. The province of Punjab has announced that it has decided to impose a lockdown in areas with potential COVID-19 hotspots in seven cities of the province namely, the cities of Lahore, Rawalpindi, Faisalabad, Multan, Gujranwala, the UCCRTF city of Sialkot.

The following day, 904 further lockdowns were imposed in Punjab; 26 in Sindh; 572 in Khyber Pakhtunkhwa; 29 in Azad Kashmir; 10 in Islamabad; and 5 in Gilgit-Baltistan. Around the country, authorities are attempting to ensure compliance with health guidelines, particularly in workplaces and in industrial sector and transport markets and shops.

Although the absolute impact of the improved strategy is not known, there are early signs of improvement in some parts of the country. For instance, in Islamabad 771 cases of coronavirus were reported on June 1st, a number that has since fallen to 25 cases as of the 5th of September 2020. After reporting its first cases on February 26, Pakistan has so far officially registered nearly 213,470 confirmed cases and 4,395 deaths. Of those infected, more than 100,802 have recovered.

This article was originally posted on ADB’s Livable Cities blogsite.
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Integrated Coastal Management for a sustainable future in Dong Hoi

Integrated Coastal Management for a sustainable future in Dong Hoi

By Hoang Nhat Do and Rob van den Boomen

Viet Nam’s marine resources deliver huge benefits to the country’s economy, as well as providing countless ecosystem services to its large coastal zone. However, coastal zone management is becoming increasingly difficult, as a result of impacts related to climate change such as sea level rise, coastal erosion, and sand dune degradation.

The situation is especially pronounced in coastal cities such as Dong Hoi, which is gaining popularity as a tourism destination. Located in Quang Binh province in the central part of the country, the Dong Hoi’s coastline is changing rapidly, posing a threat to resident’s livelihoods and local economy. Despite the importance of Dong Hoi’s coastal zone for tourism development, the causes and long-term impacts of the region’s coastal degradation are poorly understood by local stakeholders.

With assistance from the Urban Climate Change Resilience Trust Fund (UCCRTF), administered by the Asian Development Bank (ADB), the local government is piloting the Dong Hoi Integrated Coastal Management Project. The project, a component of ADB and Viet Nam’s Urban Environment and Climate Change Adaptation Project, is restoring sand dunes based on evidence generated from scientific surveys and stakeholder consultations.

The pilot is being delivered by an expert consortium of international and national specialists led by Dutch consulting engineers Witteveen+Bos, Hanoi University’s Center for Environmental Fluid Dynamics (Hanoi University), and Van Phu JSC. Since 2018, they have been conducting studies, capacity building activities, and raising public awareness on coastal zone management.

Image: Changes in the shoreline is evidenced by the increasing proximity of the buildings, and the collapse of building foundations.

Technical information and community integration

Exploratory studies that seek to determine the way that the Kien Giang river behaves and moves sediment, and the development and migration of the dune system in Nhat Le estuary are crucial to the design of sand dune restoration. These studies in hydrodynamics, bathymetry and other morphological assessments, provide a detailed picture of how the process of sedimentation in the river mouth contribute to severe flooding upstream, and cause problems for river and marine transport navigation. They also show the impact of annual dredging, which negatively affects the condition of the beach.

The results of these studies and ongoing monitoring and observations have helped to identify actions that can help to sustainably adapt and maintain the river mouth and the coastline. The site for the pilot was chosen in May 2020 with the agreement of Quang Binh Provincial Government. To ensure the project’s success, the initiative has been designed to involve a wide range of stakeholders, including government agencies, local fisherman, and women and children’s groups. Each have been consulted and received customized training courses about sustainable nature conservation.

It is hoped that that by 2021, the flagship project will be well underway and serve as a model of best practice to other coastal towns in Viet Nam and beyond.

This article was originally posted on ADB’s Livable Cities blog.
Cover photo by Clay Gilliland / Wikimedia Commons.
Understanding the economic costs and benefits of urban resilience in UCCRTF cities in Bangladesh

Understanding the economic costs and benefits of urban resilience in UCCRTF cities in Bangladesh

By Matthew Savage

ADB’s Urban Climate Change Resilience Trust Fund (UCCRTF) has begun working on a number of case studies looking at the economic benefits of investment in urban resilience. These studies examine the historical socio-economic vulnerability and exposure of selected cities to a range of climate impacts and stresses such as flooding and cyclone damage. The purpose of the studies is to assess the potential economic benefits of investing in resilient infrastructure and better city-level planning and capacity. It is hoped that a more comprehensive appreciation of the economic value of avoided damages will bolster the case for climate-resilient investment. 

The first case study examines the secondary cities of Bagerhat and Patuakhali in Bangladesh, both of which are located in the low-lying coastal flood plain. These cities have been regularly impacted by large-scale cyclone events, such as Cyclone Sidr in 2007, which affected more than 200,000 people within the city boundaries. The cyclone destroyed roads, buildings, schools, colleges and other infrastructure, and killed more than 4,000 people across the coastal region. [1]

In support of the project preparation work for ADB investments in Bangladesh, UCCRTF financed the formulation of climate resilient integrated urban plans for seven towns, including Bagerhat and Patuakhali. Among the coastal towns, the two were determined to be the most vulnerable to impacts of climate change so the trust fund allocated an additional $6 million to the ADB Coastal Towns Environmental Infrastructure Project (CTEIP) (44212-013) to finance the construction of cyclone shelters, emergency access roads and drains, as well as the preparation of integrated drainage plans (IDP) and fecal sludge management (FSM) and solid waste management (SWM) plans in Bagerhat and Patuakhali.

In May 2020, these investments were put to the test when Cyclone Amphan, the most serious Category IV cyclone since Sidr, hit the Delta. In Bangladesh, the storm impacted more than 2.6 million people. More than 200,000 houses were fully or partially damaged, along with more than 44% of educational facilities. Bagerhat and Patuakhali were among the five worst impacted districts of Bangladesh. [2]

While full assessment work on damage and recovery costs is currently ongoing, what is becoming clear is that many of the most significant impacts of the cyclone in the two cities were able to be reduced, in part thanks to investments in resilient infrastructure and planning by ADB and UCCRTF.

Better early warning systems, comprehensive evacuation plans, and more robust cyclone shelters led to significantly lower levels of deaths and injury, with a total of 26 deaths across the whole of Bangladesh, of which only two were from Bagerhat and Patuakhali districts. This was of a magnitude lower than in previous similar scale events. [3]

Furthermore, an initial review indicates that UCCRTF infrastructure investments remained operational when the cyclone hit.[4] More robust and resilient roads supported the movement of people across the municipal region as part of the evacuation. Investments in higher capacity drainage systems also helped the cities cope better with intense rainfall and coastal or river flooding.

The UCCRTF team is currently engaging with the local authorities in both cities to obtain more detailed insights into the damage incurred as well as the potential avoided damage costs resulting from recent investments in improved resilience. As a result of COVID-19, the economics team have been undertaking remote videoconferences with the mayors and senior engineers in the cities, supported by the project’s Country Resilience Officers on the ground.

The case study, due later this year, will provide more detailed evidence on the socio-economic benefits of investing in resilience in terms of avoided costs and other livelihood and productivity benefits. Wider assessments of the economics of resilience suggest that the benefits of such investments in vulnerable urban environments are at least double the cost, and that improvements in city-level planning and preparedness have the potential to drastically reduce the human cost of climate disasters.

​This will be the first in a series of economics of resilience case studies, with others tentatively planned for Hue in Viet Nam and La Trinidad in the Philippines over the coming months. ​

This article was originally published on ADB’s Livable Cities Blog.
Cover photo from Pikist.