Greener, Greater Cities


  • What should a “green” city look like? Should it resemble Copenhagen, with its high rates of bicycle commuting and recycling? What about Curitiba, the capital of Brazil’s Paraná state, with its pedestrian-centered planning? Or perhaps Ethiopia’s capital, Addis Ababa, which is powered entirely by renewable energy?
  • With more than 50% of the world’s population now living in urban areas – a share that is rising fast – the answer to this question will shape our collective future.

Sustainable infrastructure and smart urban planning:

  • Nature is the world’s original infrastructure, and nature-based solutions can help cities address some of the biggest planning challenges they face, such as air and water pollution, water scarcity, and extreme heat, all of which are now being exacerbated by climate change.

Nature-based solutions:

  • As planting trees along streets demonstrate, such solutions do not have to be complicated.
  • Street trees, research shows, can help reduce air pollution – the single biggest threat to human health, especially in urban areas, according to the World Health Organization – by filtering fine particulate matter, such as that emitted by internal-combustion engines. They are also highly effective at combating the “urban heat island effect,” which can result in dangerously high summer temperatures.
  • Moreover, planting trees in lower-income, under-resourced neighborhoods, which often have less canopy cover, can help to mitigate environmental inequality. 

Major urban challenge is water management:

  • The materials that compose modern cities are mostly impermeable, so they cannot absorb rainwater.
  • As a result, during heavy storms, the runoff overloads drainage systems, causing pollutants to run through city streets and into local ecosystems.
  • Rain gardens – small pockets of native vegetation planted in natural depressions and low points – can resolve this problem by collecting and filtering rainwater, so that it can be reabsorbed by the Earth, resulting in recharged aquifers and increased biodiversity.
  • In Chinese “sponge cities” such as Shenzhen, rain gardens, together with green roofs and artificial wetlands, are already being used to manage storm water, aided by permeable paving materials that allow water to filter through to the substrate.
  • Natural interventions beyond a city’s borders can also help to address water-management challenges.

Nature-based solutions may not be sufficient:

  • Nature-based solutions may not be sufficient to solve all of the challenges facing a particular city.
  • Urban areas may also need well-designed, sustainably built infrastructure to manage air and water, and integrated clean-energy systems and efficient public-transit options to help reduce pollution and carbon emissions.
  • But nature-based solutions – if sufficiently funded and implemented in an equitable manner – offer benefits that we can no longer afford to ignore.
  • The technology and infrastructure that have allowed cities to flourish in the past carried high costs, from pollution to flooding to biodiversity loss.
  • As climate change reshapes our planet, these threats are growing and shifting, compounding the challenge further.


  • We cannot solve the problems created by concrete and turbines with more concrete and turbines. We need flexible solutions that can make our cities more resilient, sustainable, and adaptable, without undermining the urban dynamism and prosperity on which we rely. Nature itself can offer such solutions and be a catalyst for healthier, more vibrant neighborhoods, driving investment and making cities more successful by any measure.

Source: Project Syndicate

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