By C40 Executive Director, Mark Watts

I’ve just returned from Brazil, where the nation was responding to the tragedy of climate breakdown-induced flooding which had displaced half a million people in Rio Grande do Sul. It has been a crushing reminder of the deadly impact of polluting our atmosphere, in a nation that will host the G20 this year and critical climate talks next year. However, I also found lots of reasons for hope on this trip, including in Brazil’s largest city, São Paulo, where Mayor Nunes is beginning an expansive new green space programme on a breathtaking scale.

The ambition of the project is extraordinary. Mayor Nunes has signed a decree expropriating 10.9% of the city’s private green area to create a vastly enlarged series of protected forests and public parks. By the time it is complete, the total area of public green space will be the size of Paris and the largest land purchase ever secured by a mayor for green areas within a city. 

Mark Watts is accompanied by Gregor Robertson, and a delegation from C40 Cities and the City of São Paulo. They look out onto the green space currently under expansion.

One of the aims of the project is to support biodiversity, and Mayor Nunes had his team identify the areas carefully, prioritising native forests and watersheds. The initiative will transform the city for those who live there, with thousands of people gaining access to green space for the first time. It is estimated that 10,000 jobs will be directly created through the parks, and many more indirectly through the new services it will inspire, from outdoor pursuits to biomedicine.  

The juxtaposition with the dreadful flooding in the south of Brazil was strong. Following several days of record rains – which scientists say were made twice as likely by the burning of fossil fuels and trees – residents of the southern city of Porto Alegre were left almost entirely cut off by the floods, with an estimated 80% of the population without access to running water.

Increasing green space in urban areas is an effective way to reduce flood risk in cities by increasing permeability. In São Paulo, the new park maintenance staff are being trained as firefighters too, in response to the increasing wildfire risk caused by climate breakdown.

Mayors know that increasing nature in cities is one of the best ways to mitigate the impacts of the climate crisis while improving health and wellbeing for residents, and São Paulo is one of 41 cities that has set ambitious goals for green space as part of C40’s Urban Nature Accelerator.

Last year, Paris welcomed 74 new or renovated green spaces across the city, while Chennai is developing 57 sponge parks to mitigate flooding in low-lying areas. Wuhan has added large-scale greenery along the Yangtze River to act as a ‘sponge,’ which has the additional benefits of increasing the carbon sequestration capacity of the city and alleviating the urban heat island effect. Nature-based solutions are also a great way to create green jobs – Freetown’s initiative to plant more than 1 million trees created over 1,200 jobs in 2020 – 2021. Mayor Aki-Sawyerr is just about to plant the millionth tree. 

I met the Mayor of Addis Ababa after my trip to Brazil and she told me she could top all of this – her city has planted a stunning 40 million new trees in the last decade!

As the impacts of the climate crisis continue to increase in our cities, so does the need to build resilience. São Paulo is a leading example of a city taking transformative action to build a better city for all. 

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