The Blue-Green Dream

In 2009, the Copenhagen City Council decided that climate change was real. About time: the same year, close to 115 world leaders gathered there as part of the United Nations Climate Change Conference to say as much—and to sign the Copenhagen Accord, which set a worldwide goal of limiting rising temperatures to 2 degrees Celsius above preindustrial levels. For the city, climate change was also becoming more personal; faced with the prospect of extreme flooding burying low-lying cities like the densely populated Danish capital, Copenhageners decided that it was time to preempt Mother Nature.

Denmark is distinctly flat. Its highest point is a mere 171 meters above sea level. That never much seemed like a problem; for centuries, Danes had managed to build an increasingly prosperous society despite occasional flooding. But suddenly, low elevation mattered a great deal.

That’s why the Copenhagen City Council decided that unless they started adapting their city for a rising sea level and regular extreme-weather events, it would become uninhabitable. As the European Commission noted in a 2010 report, “precipitation in Copenhagen is expected to increase by 30 to 40% by 2100, while water levels around the city are likely to rise by 33 to 61 cm over the next decade.” With each flooding would come impassable streets, ruined houses, and a disabled underground system. And every time, after the weather crisis had passed, all those things would have to be repaired at great expense. And so the city’s climate-change adaptation plan was developed, with the aim of making the city livable for the long term—and carbon neutral to boot.

“Drainage systems will be significantly improved,” the planners promised, “so that they are capable of coping with major downpours.” A range of new infrastructure would be created “for better rainwater management—such as rain and sewage reservoirs, and sustainable urban drainage systems. Contaminated run-off from the city’s roads will also be treated.” The council went further to promise “pocket parks,” green roofs, and green walls.

It sounded nice. But in 2011, before these projects had even gotten off the ground, a catastrophic cloudburst—extreme flooding—hit the city; it drowned large parts of Copenhagen under a meter of water and left the nation with one billion dollars in expenses. For the planners, the lesson was that new drain systems and walls wouldn’t be enough. They would have to work with nature rather than against it, and so to the plans were added the creation of new meadows, miniature hills and valleys, and parks that could also serve as rain basins—call it “blue-green” development for the combination of water and vegetation, as opposed to the usual gray.

It was all going to be expensive, but city decision makers and officials compared it to the cost of doing nothing: 60–90 million dollars each year for the rest of this century. They also knew that creating appealing solutions, not merely functional ones, would be necessary; policy makers believed that taxpayers would be happier paying for climate change adaptation—and CO2 reduction—if doing so also resulted in a more habitable city.

Finally, some five years later, in 2016 the plans came to fruition. The city was building its first climate change-adapted neighborhood. St. Kjeld, as the neighborhood is called, saw much of its omnipresent asphalt torn up and replaced with pocket parks—hilly meadows separated by elevated walking paths—and so-called cloudburst boulevards lined by elevated sidewalks. The blue-green solution was not just more attractive than the massive sewers that would otherwise have been needed; it also cost less. In adopting this solution, the architects and city planners went against decades of urban design practice by not removing little elevations to create a perfectly level area on which concrete could be poured, but by instead creating, with natural means, little hills and valleys. “It’s a huge amount of water that we’ll have to redirect when the next cloudburst hits,” Flemming Rafn Thomsen of Tredje Natur, the Danish architecture firm chosen for the project, told me at the time. “We looked at St. Kjeld and thought, ‘That’s a lot of asphalt with no function. We can use some of that space for water.’” And so the boulevards were designed to collect rainfall and lead it to parks or the harbor while allowing locals to safely move around on elevated sidewalks.

Nearby, in the Copenhagen neighborhood of Sydhavnen, South Harbor, city planners likewise decided to kill two birds with one stone by beautifying a large dead-end street while turning it into an emergency water reservoir. “We created a raised boardwalk and eight sunken gardens, each with their own theme,” Lykke Leonardsen, Copenhagen’s head of resilient and sustainable city solutions, told me in September. “One is, for example, a butterfly garden. Each of these gardens can be filled with rain, but the gardens have also turned the street into an inviting place when it isn’t pouring out. You always see people walking on the elevated sidewalks. And you never see any garbage! You might think that eight big holes would invite garbage. But people appreciate this space.”

In Vesterbro, a third Copenhagen neighborhood, the city turned a depressing former sports field in a park into a sunken area—now attractive-looking and suitable for sports—surrounded amphitheater-style by rows of seating areas and strips of grass. When Copenhagen next floods, the area will function as a reservoir. The water will be kept and used for municipal purposes, including fountains and watering plants in city parks. “But the good thing is, if you’re walking in the park, you can’t tell that you’re walking in a water reservoir,” Leonardsen said to me. “You’re just walking in a nice park. We want to create places that also work when they’re dry and make these neighborhoods attractive and livable.”

So what’s not to like?

Cities Opt for Nature

October 2021 brought not just fearful messages out of COP26 in Glasgow, but yet another reminder of why climate change adaptation is an urgent task—especially for cities. Early that month, 29.2 inches of rain fell on the Italian town of Rossiglione within 12 hours, the heaviest rainfall ever recorded in Europe. The rain fell so violently that it was easy to see where the word “cloudburst” comes from: it was as if the clouds had exploded and emptied their contents on the town, where streets and sidewalks quickly became unusable. Indeed, even the bottom floors of some homes became deadly traps. A similar tragedy had played out in the northeast United States the month before, when more than 45 had died, some trapped in basement apartments and others in cars, during intense flooding.

The deluges seemed to bear out what an international team of scientists predicted in the respected academic journal The Lancet Planetary Health over the summer: “extreme precipitation patterns are increasing both urban drought and flood risk. Rising sea levels, coupled with other environmental issues in coastal cities, have triggered environmental and social change with no historical parallel.” “Cities in Europe, South America, and Africa face stronger and more frequent droughts,” the scientists warned.

Half the world’s population already lives in cities, and that level is predicted to rise to over 70 percent by 2070. “Cities are where the action needs to take place because most people live there,” Pernille Jægerfelt Mouritsen of Nordic Sustainability, a Danish sustainability consultancy, told me in a telephone conversation this October. “As we saw in Germany this summer,” she warned, “climate change is coming closer.”

What happened in Germany in July was similar to what befell Rossiglione or New York, but multiplied. Within 24 hours, more water fell on the German states of Rhineland-Palatinate and North Rhine-Westphalia than would ordinarily fall during the whole month of July, practically burying the district of Ahrweiler under water. To date, 180 people are recorded as having died in the flooding, but the real figure is likely to be higher, as dozens are still missing months later. For days, Ahrweiler was sealed off from the rest of the world; it could only receive deliveries of food and other vital items thanks to the Bundeswehr, which built a temporary bridge.

All this makes clear that cities do need to prepare for extreme weather, but if they do it in ways that make the city less appealing, they’ll fail. In New York City, the city administration found a flood barrier made of sand bags at South Street Seaport unacceptably ugly and invited local artists to apply to decorate it. What’s more, flood walls may no longer be able to withstand the water coming their way. This September, Hurricane Ida broke through a 22-foot tall and 18-inch thick flood barrier in Pennsylvania.

Perhaps in response to such realizations, as Mouritsen explained to me, “more and more cities are moving away from concrete adaptation to nature-based ones. It’s obviously the right thing to do for the environment, but cities also have to adapt to climate change to make sure they’re beautiful places where people want to live.” Indeed, cities that can combine adaptation with beautification may be ensuring their survival in two ways: staving off environmental destruction, while also making themselves attractive to existing and prospective residents. To be sure, global knowledge workers are not (yet) being polled on cities’ climate change adaptation efforts, but in a 2020 report the real estate company JLL and the consulting firm The Business of Cities pointed out that the factors deciding a city’s success are no longer purely economic ones, but also include aspects such as urban experiences, innovation, and sustainability. As JLL’s research director notes, “cities that are most successful in addressing these areas and embracing new economic models—the innovation economy, the experience economy, the sharing economy, and the circular economy —will be the most future-proof.”

There’s a side benefit as well, as Copenhagen’s leaders surmised: even though city planners, politicians, and the public are increasingly aware of the enormous cost of doing nothing, allocating the money for overarching climate change adaptation is a struggle. That’s why the kind of climate mitigation plans that can actually pass the political process must combine both needed infrastructure and aesthetic improvements that taxpayers like. While no individual climate change measures have been put to a vote in a referendum in Denmark or elsewhere, Copenhageners seem to approve of their city’s handling of climate change and other matters: the same party has led the city since 1938.

And so cities around the world have launched a colorful range of initiatives.

Barcelona’s “superblocks,” areas of some 400 by 400 meters that are pedestrian-only, reduce traffic (cars are routed around the blocks) and increase and enhance space for local residents. They have become so popular with the residents that other cities are adopting the concept. Paris, for instance, is reclaiming city life for pedestrians by pioneering the “15-minute city” concept, which aims to allow residents to find everything they need in local shops.

Meanwhile, Amsterdam has begun recycling construction waste, which it anticipates will lead to a 2.5 percent reduction in CO2 emissions, and Houston is recycling building materials for the same reason. When COVID-19 hit, metropolises including Berlin, Paris, and Mexico City expanded bike lanes or opened new ones to allow more people to travel safely—a move that, of course, both reduces CO2 emissions and may increase the cities’ attractiveness.

Rotterdam—home to Europe’s busiest port, where dozens of megafreighters arrive and depart every day of the week—is another climate-adapting pioneer. The port has begun funneling some of the heat its operations generate to nearby homes and other buildings. It is also starting to use more energy produced at offshore wind farms, and plans to make itself a hub of CO2-neutral hydrogen production. The port is jointly owned by the city of Rotterdam and the Dutch government, and they too consider climate change adaptation not just a burden but an opportunity to increase the attractiveness of their city and country.

Indeed, steps taken by the city of Rotterdam itself go even further. Rotterdam is surrounded by bodies of water and faces submersion, with large parts being below sea level. It hopes to “climate-proof” itself by 2025. To do that, the city is reinforcing dikes and flood-proofing buildings and public spaces. But like Copenhagen, Rotterdam is also trying to embrace its water-filled future. In concrete (forgive the pun) terms, this means parks-cum-reservoirs like the Benthemplein water plaza. Previously a nondescript and usually empty square, the Benthemplein plaza now looks like an amphitheater (and can be used as one) and doubles as a basketball court and skateboard park. In case of a deluge, the plaza becomes a gigantic water-storage bowl.

Last year, Rotterdam also completed its first floating street, featuring rows of houses built on barges. “The houses are well insulated, produce their own energy through solar panels, generate heat via a biomass installation, and clean their own wastewater,” the city reports. And since the projects are classed as residential real estate, “banks are prepared to extend regular mortgages to future residents.” Indeed, the floating homes’ architects see considerable potential for more such streets in former industrial areas.

To date, there’s no regular opinion polling on key cities’ climate change adaptation efforts. Positive headlines are, however, a good indicator. Google Rotterdam and climate change, or Copenhagen and climate change, and you’ll get stories describing their impressive initiatives. Google a city like Los Angeles and climate change, and you’ll conclude that living there won’t be very enjoyable as climate change takes hold. Of course, people busy trying to make ends meet will not be googling cities to find the ones with the most attractive climate change adaptation design. Even within the Western world, climate change could thus create yet another have-have not divide, where poorer cities lose high-income workers—who are geographically flexible—to already wealthy cities that can invest in innovative climate change solutions, while residents who can’t move are left behind with only the most rudimentary, visually unattractive, and less livable solutions.

Beyond Beauty

Of course, climate change adaptation and climate change mitigation can be more utilitarian too, as shown in other efforts by Copenhagen, which has pledged to be carbon neutral by 2025. Jørgen Abildgaard, Copenhagen’s executive climate project director, has the bewildering task of rolling out a broad array of new initiatives at the same time. The city is developing carbon-capture installations and is trying to turn more of its waste into energy. Converting waste into energy will, city planners calculate, cut Copenhagen’s CO2 emissions by 300,000 tons per year—only a small share of its total, but a reduction nonetheless. (Copenhagen has asked the European Union for funding.) “Using waste for energy has a double benefit: it reduces CO2 emissions and reduces waste,” Abildgaard told me in September. “We already have a new incinerator plant in place for this energy. It’s absolutely critical for us to become CO2 neutral by 2025.”

Even though Copenhagen has reduced its carbon emissions by more than 57 percent between 2005 and 2018, there is a big chunk left. Both new offshore wind installation and the waste-to-energy plant are scheduled to be completed by 2025. “We’re also planning a 400 megawatt windpower installation in Oresund [the strait between Sweden and Denmark], which will be completed by 2025,” Abildgaard said to me. “Together with onshore wind turbines, it will power Copenhagen. It’s not a radical reduction in CO2 but it’s an important signal.” Meanwhile, to better dispose of carbon dioxide, Copenhagen plans to install capture facilities—another expense. “But not as expensive as other activities that will be required if we don’t act now,” Abildgaard is quick to emphasize. “Carbon capture is a known technology. The challenge is scaling it. It’s important to have cooperation with the right partners—partners who also want to be on the forefront and be standard-bearers of innovation.”

As with its pocket parks attracting new residents, Copenhagen is trying to turn CO2 capture into an asset by recycling the calamitous emissions—for example, as fuel for ships and aircraft. And the Denmark-headquartered pharmaceutical giant Novo Nordisk has teamed up with Danish universities to launch a biosustainability research center outside Copenhagen. “Copenhagen is obviously only a small part of global reduction, but we’re an important facilitator of solutions,” Abildgaard noted.

The problem, of course, comes when needed solutions offer no added beauty or convenience to residents. Consider the devastating effect should a subway system like the New York City Subway, London’s Tube, or Copenhagen’s Metro be flooded. The potential damage from such disastrous events illustrates how the effects of climate change can’t be conjured away merely through innovative city design. To prevent catastrophic subway flooding—which would quickly cause a modern city to grind to a halt—massive amounts of rainwater must be channeled under the ground, out to the harbor. Such pipelines don’t make a city look prettier. And without national legislation, it’s not obvious who should pay. It isn’t obvious either how to get such legislation passed, especially when improvements cost cities and countries a lot of money. Then again, if residents and prospective residents are won over with visually appealing solutions, they may be more amenable to accepting the less glamorous ones that are indispensable if cities are to have a chance of preventing constant disruption and destruction.

We are, of course, in today’s mess because previous generations failed to take precisely such collective and expensive measures. In her speech to the COP26 delegates, Queen Elizabeth II noted that 52 years ago Prince Philip “told an academic gathering, ‘if the world pollution situation is not critical at the moment, it is as certain as anything can be that the situation will become increasingly intolerable within a very short time. If we fail to cope with this challenge, all the other problems will pale into insignificance.’” That is happening, and pretending cities can adapt to climate change through pretty measures alone would be naïve. Fortunately, pioneering cities such as Copenhagen are far beyond that stage. The fact that they began their efforts years ago means other cities can now use their ideas and insights when getting serious about climate change adaptation and mitigation. And that’s a good thing, because they have to hurry up.