Nature-Based Solutions on the Rise to Protect Cities from Environmental Hazards

Jul4,2024
Nature-Based Solutions on the Rise to Protect Cities from Environmental Hazards


Faced with an ever-increasing risk of flooding and wildfire, São Paulo, Brazil, is embracing nature-based solutions at a “breathtaking” pace, expanding its public green space this past spring by 11% with a stroke of a pen.

Recent floods that displaced half a million people in Brazil have been a “crushing reminder of the deadly impact of polluting our atmosphere” writes C40 Cities Executive Director Mark Watts in a recent post on LinkedIn. However, he adds, the initiative by the country’s largest city to expand and protect the climate-buffering power of public green spaces offers “lots of reasons for hope.”

São Paulo is far from alone in using the power of nature to combat environmental hazards in urban areas. It’s part of an international network of 41 cities that have pledged to increase their use of nature-based solutions (NBS), including Montreal and Toronto. The approach is on the rise in other Canadian cities, as well.

But São Paulo is earning accolades for the scale of its commitment. Back in February, Mayor Ricardo Nunes signed decrees declaring 32 private parcels of green space a public utility. Taken together, the newly public lands encompass 16,531 hectares, almost 11% of the city’s territory. Nunes’ move means 26% of São Paulo is now under environmental protection.

The scale of the land acquisition is “breathtaking,” writes Watts. “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.”

The “transformative” expropriation was undertaken to buttress the innate climate resilience of the city’s abundant green spaces, since natural ecosystems are permeable and less prone to flooding. While São Paulo escaped the May floods that ravaged the state of Rio Grande do Sul, 1,000 kilometres to the southwest, it has often experienced severe flooding in the past, according to a January, 2015 article in the journal Habitat International, and the risk of future flooding is high.

A deliberate effort to protect native forests and local springs will also deepen biodiversity protections.

Expanding São Paulo’s public green space will also mean new employment. “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,” Watts writes.

Nunes’s move is also a win for environmental justice, Watts adds. The additional public parklands mean “thousands of people gaining access to green space for the first time.”

One of 41 cities that have signed up to be part of C40’s Urban Nature Accelerator, São Paulo has committed to significantly “enhancing nature within [its] urban environment” by one or both of two pathways by 2030.

The first pathway, focusing on “quality total cover” (to mitigate both flooding and extreme heat) pledges to ensure that 30-40% of the “total built-up city area” is either green space (street trees, urban forests, parks) or permeable space (equipped with permeable pavements, swales, infiltration trenches). The second pathway, focusing on “accessibility and connectivity,” commits that 70% of a member city’s population will live within 15 minutes on foot, by bike, or via transit of a “fit for purpose green or blue space.”

Other cities that have signed the Urban Nature Accelerator pledge are Amman, Austin, Athens, Barcelona, Berlin, Bogotá, Buenos Aires, Chennai, Copenhagen, Curitiba (Brazil), Delhi, Dhaka North, Dhaka South, Durban, Freetown, Guadalajara, Haifa, Karachi, Lima, London, Los Angeles, Medellín, Milan, Montreal, Mumbai, New Orleans, Paris, Quezon City, Quito, Rio de Janeiro, Rome, Rotterdam, Salvador, San Francisco, Seattle, Stockholm, Sydney, Tel Aviv, Tokyo, and Toronto.

Efforts to grasp—and share—the intricate business of using NBS to help solve some of humanity’s biggest problems, especially urban ones, are accelerating in Canada.

Published in March, a review by the International Institute for Sustainable Development (IISD) cites Nelson, B.C.; the Halifax Regional Municipality; and the City of Edmonton’s EPCOR as three “bright spots” of best practice in using NBS (also known as natural infrastructure) to deliver services traditionally associated with so-called “grey” infrastructure, such as storm drains, dams, and water treatment facilities.

The review is a product of Natural Infrastructure for Water Solutions, a five-year initiative led by IISD to scale up natural infrastructure across the Canadian prairies. It shows how leveraging local bylaws, embedding the concept of natural infrastructure across multiple levels of policy and planning, taking a hybrid approach that combines natural infrastructure and grey infrastructure to reduce risk, and normalizing the idea of natural infrastructure through interdepartmental collaboration will be critical to success.

In April, the Natural Assets Initiative, in partnership with the Greenbelt Foundation and the Municipal Finance Officers Association of Ontario, published a guidebook advising local governments on NBS best practices. The guidebook draws on the experience of several municipalities in Ontario, as well as Saskatoon, Edmonton, Calgary, and Saanich, B.C. It reviews existing regulations and standards, advises on how to take a natural assets inventory, and explains how to determine the “level of service” provided by a natural asset.

Other efforts include a recent webinar co-hosted by the Tamarack Institute, Climate Caucus, Climate Reality Project Canada, Clean Air Partnership, and the David Suzuki Foundation. Key takeaways included the critical importance of Indigenous knowledge in protecting, restoring, and utilizing natural infrastructure.