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31 cities commit to green infrastructure targets

13 July 2021

by Sarah Wray

Thirty-one mayors have signed the C40 Cities Urban Nature Declaration, pledging to invest in green spaces to improve air quality and bolster protection against climate impacts such as extreme heat, flooding and drought.

The signatory cities, which include Athens, Copenhagen, Los Angeles, Paris and Tokyo, have committed to deliver on one or both of two key targets. By 2030, 30 – 40 percent of city surface area should consist of green or blue infrastructure. This includes street trees, urban forests and parks, as well as sustainable urban drainage systems and permeable pavements. With a focus on equitable distribution, the Declaration sets a target for 70 percent of a city’s population to have access to green or blue public spaces within a 15-minute walk or bike ride by 2030.

“Supporting and protecting cities’ natural ecosystems is one of our most important tools for building resiliency against the climate crisis and creating the healthy, inclusive urban communities we deserve,” said Mark Watts, C40 Cities Executive Director. “Throughout the COVID-19 pandemic, we were reminded that accessible, green spaces are essential for liveable, climate-ready and crisis-prepared cities. As we seek to deliver a green and just recovery, investing in and implementing nature-based climate solutions will be imperative to public health and well-being, as well as the success of global efforts to tackle the climate crisis.”

Green infrastructure plans

Examples of cities’ plans to achieve these targets include:

  • In Guadalajara, 67,000 new trees will be planted across 70 green corridors, and over 50 new public gardens will be introduced to cool down the city and provide shade and leisure space. The city is funding courses to train gardeners and tree technicians, and providing 400 workshops for residents on caring for trees and gardens.
  • Under Toronto’s Urban Forests Grants and Incentives programme over 13,000 trees and shrubs will be planted, and citizens will be involved through planting events, educational workshops and youth programming.
  • In Mumbai, the Maharashtra government is making amendments to the ‘Tree Act’ to protect and conserve old trees and prevent felling of trees.
  • Through the Green Roofs Competition, Barcelona is subsidising 75 percent of the cost of new green rooftops for winning projects to create urban allotments and space for renewable energy generation, rainwater collection and composting.
  • The Transformative Riverine Management Programme in Durban (eThekwini) aims to improve resilience and create thousands of green jobs.

Giuseppe Sala, Mayor of Milan, said: “In Milan, we are committed to plant 3 million trees by 2030, to use nature-based solutions to increase resilience and protect citizens from the climate crisis, to refresh our neighbourhoods with green areas and water, and to regenerate the urban environment in a sustainable manner. Our commitment is to the people and the planet at once.”

Within two years, the 31 cities will make their nature goals public and report annually on progress.


C40 cites several studies which highlight the benefits of green and blue infrastructure.

For example, in Medellín, temperatures have reduced by 2°C as a result of planting more than 10,000 trees for the city’s Green Corridors project. Researchers in Portland, Oregon found the city’s urban trees cut nitrogen dioxide levels resulting in significantly fewer respiratory problems, valued at US$7 million in healthcare savings annually.

The full list of cities that have signed the Urban Nature Declaration are: Athens, Austin, Barcelona, Berlin, Bogotá, Buenos Aires, Copenhagen, Curitiba, Durban, Freetown, Guadalajara, Haifa, Lima, London, Los Angeles, Medellín, Milan, Mumbai, New Orleans, Paris, Quezon City, Rio de Janeiro, Rome, Rotterdam, Salvador, Seattle, Stockholm, Sydney, Tel Aviv, Tokyo and Toronto.

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