If a plane door drops onto a roof, will anyone hear?

Copenhagen looks at green roofs as it prepares for a changing climate

October 10, 2013


Visualise the world in 2050: convex streets that collect water from superstorms and pocket parks that absorb heat and can be turned into reservoirs. Welcome to Copenhagen, where planners are preparing the city for the effects of climate change several generations from now.

"We've looked at how climate change will affect Copenhagen in the long-term future", says Lykke Leonardsen. "For Copenhagen, the most serious effect of climate change will be increased precipitation, so we've developed a plan that addresses how to catch all the rainwater in the city." Leonardsen, a city planner, belongs to the 10-person team working solely on long-term climate change adaptation, planning ahead to the year 2100.

Like any city located by the sea, Copenhagen will face particular danger as sea levels rise and superstorms hit coastal areas with greater frequency. "In adapting to climate change, cities can choose either grey or green infrastructure," says professor Stuart Gaffin, a research scientist at the Center for Climate Systems Research at Columbia University, who also advises the New York City government on climate change adaptation. "Grey infrastructure means building walls and barriers. In New York's case, we'd lose Long Island if we went for the grey option. The green option, which has growing support, includes green roofs, green streets that will capture storm water, and pavements that allow water to percolate through." That's the option Copenhagen has chosen.

Leonardsen's team envisions lowering the level of a local lake, thereby freeing space around its shores. This space will then be turned into a park, with playgrounds and running paths. When a superstorm hits, the lake and its surrounding park will be used for water storage. And those convex streets? They are main thoroughfares designed by Copenhagen's city planners to capture water from storms and flooding and direct it to the harbour. Copenhagen in 2050 will also feature smaller streets with plenty of trees, which will slow anticipated flooding "so not everything comes bursting into the cloudburst boulevards at the same time", Leonardsen explains. Pocket parks will absorb heat and can be turned into water storage during weather emergencies.

In addition to storms, flooding and rising sea levels, heatwaves are the most dramatic scenario facing cities as climate change worsens. If all goes according to plan, Copenhagen's sustainable climate change adaptation plan – which recently won the Index Design Award – will be completed by 2033. To be sure, Danish city planners operate in an enviable setup, where politicians and local residents alike support sustainable climate change adaptation and are willing to commit the funds required.

Brian Vad Mathiesen, an associate professor of development and planning at Aalborg University, says: "The difference between Copenhagen and other major cities is that they're very concrete in the short term and also look at what they need to do for the very, very long-term future. "But in Denmark, sustainable city planning is not a niche; it's just what we do. And you have to remember that sustainability is not just about the environment. It's also about creating local jobs." Copenhageners, in other words, have realised that doing the right thing for the environment brings jobs – and higher living standards – to the city. "Both from a financial and a sustainability perspective, it makes sense to do as much as possible as early as possible," says Mathiesen. "If you don't build things like pocket parks, you'll have problems with flooding. We can't live with flooding that brings the city to a halt for several days each time."

Other cities are embarking on similar plans. Mayor Michael Bloomberg of New York this year presented a record $19.5bn climate change adaptation plan, with 250 specific projects reaching into the 2050s. Toronto, Rotterdam and Boston, too, have advanced plans with solutions from floating pavilions to terraced levees. Some 20% of the world's cities now have climate change adaptation plans in place. "While governments are mired in negotiations, cities are leaping forward," observes Gaffin. "City populations recognise the threats from climate change." But while pocket parks and cloudburst boulevards sound charming, green infrastructure remains experimental. It's uncertain how effective percolating pavements will be, for example, and the trees in green streets face daily threats from cars. Besides, nobody really knows what the world will look like in 2050, let alone 2100.

But as far as Copenhageners are concerned, sustainable city design is the only answer to climate change. Morten Jastrup, a senior analyst at Sustainia, a Copenhagen-based think tank, says: "These measures will contribute to a higher quality of life in Copenhagen. We have to consider what will constitute a successful city in the future, because we need highly qualified people to come and work here."


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