Can coastal cities create resilient prosperity and adapt to climate change by hiding behind seawalls? Some feel they have no choice.

Communities and regions worldwide are realizing that resilient prosperity is fast becoming the most important universal goal.

That goal is both urgent and important for coastal areas. How they plan to achieve it varies widely, from the restoration of living shorelines and other green infrastructure, to hiding behind seawalls. As unattractive and expensive as the latter option is, many cities are feeling like they have no other option. And, in some cases, it might actually be the only viable approach.

In Tanzania’s commercial capital, Dar es Salaam, one of Africa’s fastest growing cities, families come to enjoy the scenic coastline along Barack Obama Drive, gazing out into the vast Indian Ocean.

This would have been impossible a few years ago, when this part of the city’s coastline was near-collapse, battered by increasingly violent waves fed by climate change. Locals can still remember when salt poisoning from the rising seawater killed the line of trees that once flanked the coastal promenade.

With support from the United Nations Environment Programme (UNEP) and the UN Office of Project Services, the construction of a seawall – built to last a century – reclaimed this area of the city. It now thrives as a flourishing business and recreation area, packed with families on holiday and newlyweds posing for photographs. For some, the wall has become a powerful symbol of hope in the face of the climate crisis, which is ravaging communities across the Indian Ocean.

This year’s World Environment Day, which falls on 5 June, marks the four-year anniversary of the official opening of the seawall. “Now opportunities are back again,” said William Buco, a local engineer and father-of-five.

Dar es Salaam is one of a growing number of cities around the world that are racing to adapt to a changing climate. Rising global temperatures, fed by human-made greenhouse gas emissions, are wreaking havoc on finely tuned climate systems everywhere from Mexico to China. Adapting to these changes is widely regarded as one of the biggest challenges of the next century and could cost developing countries alone up to $500 billion USD per year by 2050.

Cities, which are responsible for 70 per cent of our greenhouse gas emissions, are home to over half of humanity, a number projected to hit 68 per cent by 2050. The oncoming age of climate breakdown is coinciding with the largest wave of urbanization in human history, as hundreds of millions of people migrate into cities, of which many are already suffering from climate impacts.

This noxious mix of population density and an unstable climate gives way to a cocktail of urban catastrophes, from water shortages, to mega floods, to heatwaves. The latest Intergovernmental Panel on Climate Change (IPCC) report, produced by 270 scientists and researchers, notes that “an additional 350 million people living in urban areas are estimated to be exposed to water scarcity from severe droughts at 1.5°C warming.

Yet cities also pose major opportunities, not necessarily despite the growing urbanization but in some cases because of it. Although the IPCC report makes clear the threat cities face, it also maps a set of options for urban adaptation. “Global urbanization offers a time-limited opportunity to work towards widespread and transformational adaptation and climate-resilient development.

Cities are both a hotbed of climate threats and a hotbed of climate solutions,” said Jessica Troni, Head of UNEP’s Climate Change Adaptation Unit. “More and more cities are developing adaptation plans, and we’ve seen cutting-edge innovations across the world, from rainwater harvesting systems to green infrastructure. There’s no doubt that the need to adapt to climate change and urbanization can force us to re-imagine how our cities are built – and for the better.”

With that recognition, UNEP has been lending its technical support and helping governments access adaptation finance with a vast network of projects across the world’s major cities.

These projects are tackling an assortment of climate disasters, like droughts, flooding and heatwaves. In doing so, they’re using a collection of strategies, including restoring ecosystems to absorb climate impacts, building weather stations and early-warning networks, encouraging governments to develop city adaptation plans, and investing in rainwater harvesting technologies.

Some of these initiatives are taking place on a massive scale. In Lao PDR, UNEP is supporting a US $11.5 million initiative, financed by the Green Climate Fund, to draw on nature-based solutions in four cities to build resilience towards climate-induced flooding. The project is expected to benefit 700,000 people – 10 per cent of the nation’s population – by restoring urban wetland and stream ecosystems to regulate water flow and reduce flood risk.

Similarly, in cities across Latin America and the Caribbean UNEP is helping governments develop and utilize nature-based solutions to adaptation through a project known as CityAdapt. In San Salvador, for instance, the mountains slopes around the city are being reforested to absorb floodwater and halt landslides that are increasingly destructive for coffee farmers.

In an episode of the Resilience podcast, launched by UNEP last year to explore climate adaptation solutions, a coffee farmer from San Salvador, Hector Velasquez, explained: “This project has helped empower people to see what they can do to prevent or minimize the impacts of climate change.”

Velasquez tells how the water run-off down the slopes surrounding the city leads to major floods down below, “So, the more preventive work we can do at higher altitudes minimizes the risk downstream in the city. We’ve received economic assistance, but I think the most important part of it has been making us conscious of what we do and the impact on the people downstream.

The practice of using ecosystem restoration to tackle climate change is increasingly popular worldwide, as evidenced by the launch of the UN Decade on Ecosystem Restoration. During the last UN Environment Assembly in March, there was a clear interest from member states for these kinds of approaches to climate change – particularly due to their holistic benefits – demonstrated by the new resolution on the universally agreed definition of nature-based solutions.

UNEP’s CityAdapt project is also building roof rainwater harvesting systems in major cities – such as Xalapa, Mexico and Kingston, Jamaica – to increase their water supply. This is considered an essential technique for improving drought resilience. It is also providing guidance to local communities on how and why to establish such systems.

As we are seeing in India today, one of the major climate impacts affecting cities is heatwaves. Under the framework of the Cool Coalition, UNEP and partners have established an urban cooling programme to support Indian cities to take comprehensive action on extreme heat and the rising demand for cooling.

The program will provide technical assistance to 100 urban areas, helping them to incorporate solutions at the city, neighborhood at household scales. The program is drawing on best practices from around the world, many of which are outlined in UNEP’s Beating the Heat: A Sustainable Cooling Handbook for Cities.

Energy-efficient, climate-friendly cooling could avoid as much as 460 billion tons of greenhouse gas emissions over the next four decades, according to the Cooling Emissions and Policy Synthesis Report, demonstrating why the race for sustainable cooling is crucial for both reducing global emissions and building resilience.

The story of how nations tackle climate change will necessarily be a story of how we redesign and rebuild our urban environment,” said Troni. “The more we delay, the bigger the challenge becomes.

A Practical Guide to Climate-resilient Buildings and Communities, published by UNEP last year, shows how buildings and community spaces can be constructed to increase their resilience to heatwaves and a whole host of other climate impacts, be it droughts, floods or wildfire. Whilst many cities are embracing the need to adapt to climate change, UNEP’s Adaptation Gap Report 2021 finds there is an urgent need to do more.

Photo of Dar es Salaam coast courtesy of UNOPS.

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