If you take a walk through the Sawmillers Reserve, north of Sydney Harbour, Australia, you may notice a mosaic of juxtaposed rounded concrete modules installed on the man-made walls that separate land from sea. Each panel is shaped like an enormous biscuit, roughly half a meter in diameter and just over 10 centimeters thick. The modules feature five types of relief on the side facing the water, including holes, recesses, and grooves of varying sizes. The mosaics of panels, dubbed living walls, are designed to imitate the complex texture of natural rocky coastlines, in contrast to the straight, smooth lines of artificial seawalls.
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Studies carried out in this area of Sydney indicate that the number of marine species, such as algae, crustaceans, and other invertebrates, has increased by more than a third more in places where living seawalls are installed than in locations with conventional artificial walls. An article published in Philosophical Transactions of the Royal Society in 2022 found that after two years of monitoring, there was a greater proliferation of species near the living walls, which feature holes and textures that encourage the formation of tide pools, where temperatures are milder.
Living walls are one of the interventions proposed under the field of eco-engineering, which includes nature-based solutions (NbSs)—innovations, constructions, and strategies that aim to increase the adaptability and resilience of urbanized areas against risks associated with climate change, in addition to often promoting social, environmental, or economic benefits. At the 29th United Nations Climate Change Conference (COP 29), held in Baku, the capital of Azerbaijan, between November 11 and 22, biologist Ronaldo Christofoletti of the Federal University of São Paulo (UNIFESP) shared a scientific guide to NbSs that could be applied in Brazil.
In the document, titled “Blue Cities,” marine eco-engineering is one of the recommended measures for coastal environments, alongside two others: the restoration and protection of natural habitats, such as dunes, mangroves, and coral reefs, and coastal realignment, a technique that redefines the coastline, usually with a managed retreat, to control erosion and flooding. The guide also highlights eight other NbSs that can be used in both coastal and inland cities. The document was produced by the Brazilian Alliance for Ocean Culture, managed by UNIFESP, the Brazilian Ministry of Science, Technology, and Innovation (MCTI), and UNESCO, in partnership with the Boticario Group Foundation.
With funding from FAPESP, Christofoletti and Rafael Pileggi, a materials engineer from the University of São Paulo (USP), will test the impact of living seawalls made in Australia and installed on the coast of São Paulo as part of a joint project with researchers from the University of New South Wales (UNSW) in Sydney. They are establishing a partnership with the Port Authority of Santos and the city government to finalize a plan in early 2025. “We will begin practical tests at the largest port in Latin America, and then in the Santos region, whose coastline is extremely hardened,” explains Christofoletti.
Coastal hardening is the name given by scientists to the process of replacing the natural coastal landscape with manmade infrastructure, such as marinas, dikes, ports, piles, and seawalls. These interventions reduce the complexity and richness of marine habitats, replacing complex environments with smoother, more homogeneous surfaces.
Christofoletti was one of the authors of an article published in the journal Anthropocene Coasts in June 2024 that assessed the extent of artificial structures on the São Paulo shoreline and the occupation of low-lying land up to five meters above sea level. Using aerial images, he observed that the most central part of the state, especially Santos, Guarujá, and São Vicente, is most affected by the urbanization process, followed by the northern coastline and then the southern. “The less hardened the shoreline, the more resilient the city is to climate change,” says the biologist.
The holes and recesses in the living walls provide shelter with a milder climate for marine species that live near the coast. “A micro-habitat is formed in these compartments, with temperatures up to 10 degrees Celsius lower than on standard walls without eco-engineering,” explains Brazilian biologist Mariana Mayer-Pinto of UNSW Sydney, one of the leaders of the Australian study. “With regard to climate change, this means that in times of extreme heat, species are able to better protect themselves on living walls.”
Another positive aspect is that the embossed panels can be tailored to a specific objective, such as to encourage the proliferation of marine plants that capture carbon and help regulate the climate. The living walls, which have an expected lifespan of 20 years, began being installed in Sydney in 2018 and are now being used at 11 locations in Australia, as well as in Singapore and Wales.
Sensors in trees in Ibirapuera Park to measure carbon dioxide absorptionGiuliano Locosselli
In the context of climate change, the word resilience means the ability of a system to recover and maintain its functioning after a disaster or disturbance. One way to increase resilience is to implement adaptive measures designed to reduce the impacts of climate change. An October 2024 review article published in the journal Science of the Total Environment by researchers from the State University of Rio de Janeiro (UERJ), the Federal University of Rio de Janeiro (UFRJ), and independent organizations suggests that NbSs can double the resilience of cities.
“However, before implementing an NbS, we have to consider future climate scenarios predicted by the Intergovernmental Panel on Climate Change [IPCC],” says oceanographer Aline Martinez, one of the coordinators of the scientific guide, who is currently doing a postdoctorate at UNIFESP. “The new law 14,904, of June 2024, which establishes guidelines for city plans on adapting to climate change, makes this warning.” This includes, for example, considering rising sea levels and average global temperatures when designing an urban intervention.
These instruments need to exist before an NbS can be included in a municipal plan. According to data from the 2023 Basic Municipal Information Survey by the Brazilian Institute of Geography and Statistics (IBGE), only 370 of Brazil’s 5,570 municipalities have specific legislation or plans to mitigate or adapt to climate change. The MCTI’s AdaptaBrasil platform indicates that around 3,600 municipalities have low or very low adaptive capacity to deal with geohydrological disasters, such as floods and landslides.
“Adaptation essentially occurs in the local territory,” says agronomist Jean Ometto of the Brazilian National Institute for Space Research (INPE), a member of the AdaptaBrasil team. According to Ometto, mapping the risks and vulnerabilities of a city is not a simple task, and this type of concern was recently incorporated into the country’s public management after the creation of the National Policy on Climate Change in 2009.
“An adaptation plan must prioritize two major fronts. The first is to reduce the vulnerability of specific groups in society: women, children, Black people, and the elderly,” says Ana Toni, national secretary of climate change at the Ministry of the Environment and Climate Change (MMA). “The second is to prepare for an increasingly warmer world. In this regard, NbSs are of great importance.” The MMA says the Adapta Cidades (“Adapt Cities”) plan is set to be launched in the coming months, helping more than 240 municipalities prepare their adaptation plans in 2025.
“Smaller cities with fewer resources are lacking action plans and at the same time, NbSs need to be designed for cities that are more vulnerable to the climate emergency, such as those on the coast,” says architect and urban planner Deize Sanches, who is doing a postdoctoral degree at the School of Architecture, Urbanism, and Design of the University of São Paulo (FAU-USP).
“Brazil is very late in addressing the issue of adaptation,” says civil engineer Denise Duarte, also from FAU-USP. “Both in terms of scientific development and the implementation of ideas and solutions.”
Duarte is investigating thermal and environmental comfort with a focus on adaptation to heat. “Nothing can replace a tree planted in the ground,” says the engineer. “Any initiative to restore and manage existing green areas, or even the creation of new ones, is welcome.” The researcher is part of the EU Conexus project, which was started in 2020 with the aim of bringing together Latin American and European cities to encourage studies and implementation of NbSs. São Paulo represents Brazil in the initiative.
One of its projects was carried out in two large green areas in the city: Ibirapuera Park and the Fontes do Ipiranga State Park. “We installed sensors in trees to measure how much carbon dioxide [the main greenhouse gas] these parks absorb and how much they can cool the atmosphere,” explains Giuliano Locosselli, a biologist from USP’s Center for Nuclear Energy in Agriculture (CENA) and one of the members of the initiative. The monitoring program is not yet complete, but the plan is to use the data to create public policies with the aim of designing functional forests for the city. These forests would be optimized to provide the most appropriate ecosystem services for local needs, such as carbon capture and temperature cooling.
Despite a great effort to advance research and develop solutions, one thing is certain: time is running out for cities to adopt NbSs. According to the latest IPCC report, as the climate gets warmer, the effectiveness of some solutions may decrease. The IPCC therefore recommends that adaptation measures implemented now also include long-term planning. To increase the chances of NbSs being successful, experts make two recommendations: to consider the needs of local communities from the outset and to implement an evaluation system to monitor the performance of the nature-based solution over time.
Alex RamosMost urban interventions inspired by nature-based solutions have been implemented in Europe
On the global landscape of nature-based solutions (NbSs), there is a clear bias: most of the knowledge generated from research and practice is concentrated in the Global North. An article published in Nature Sustainability by Spanish researchers in January 2023 identified 216 of these interventions in 130 cities in 55 countries, finding that 63% of them were implemented in Europe. The Americas accounted for 13% of interventions, mostly in Latin America and the Caribbean. Africa also represented 13%, followed by Asia with 7%, and Oceania with 2%.
A more detailed 2013 report by the European Investment Bank and the European Commission mapped an even larger number of NbS initiatives on the continent, putting the figure at 1,300. The solutions attempt to mitigate problems related to landslides, floods, torrential rainfall, heatwaves, droughts, and coastal hazards.
In Brazil, the Observatory of Innovation for Sustainable Cities (OICS), linked to the country’s Ministry of Science, Technology, and Innovation (MCTI), has recorded a total of 40 solutions, the majority in the Southeast and South regions. However, researchers say this number may be an underestimate.
One of these interventions is the Orla Piratininga Alfredo Sirkis Park in Niterói, in the Metropolitan Region of Rio de Janeiro, inaugurated in September 2024. The local government project covers an area of 680,000 square meters and cost R$100 million. Along a 10.6-kilometer bank, the park uses a mix of NbSs, including wetlands designed to filter water flowing into the Piratininga lagoon. In November, the development was named one of the three best in the Energy and Environment category at the World Smart City Awards, an annual Spanish event.
Other NbSs identified by the OICS were implemented in Buenos Aires, Argentina, and Medellín and Bogotá in Colombia. The vertical garden in the Santalaia residential building in Bogotá city is one of them. The intervention features plant species, generally climbers, on walls, fences, and facades of the building to increase thermal comfort and humidity, and to retain rainwater. In Buenos Aires, there is the Costanera Sur Ecological Reserve in the neighborhood of Puerto Madero. Covering 350 hectares, the space is home to the greatest biodiversity in the city and helps to regulate the climate and retain rainwater.
This report is part of the Climate Change Media Partnership 2024, a journalism fellowship organized by the Internews Earth Journalism Network and the Stanley Center for Peace and Security.
The story above was published with the title “Intervention without attack” in issue 346 of December/2024.
Projects
1. Marine ecoengineering as a solution for increasing urban ecological resilience on the coast of São Paulo (nº 24/02700-4); Grant Mechanism Regular Research Grant; Sprint Program; University of New South Wales (UNSW) Agreement; Principal Investigator Ronaldo Christofoletti (UNIFESP); Investment R$94,196.20.
2. Resilience and adaptation to climate change in cities: Time to act through nature-based solutions (nº 22/08401-3); Grant Mechanism Regular Research Grant; FAPESP Research Program on Global Climate Change (PFPMCG); Agreement National Natural Science Foundation of China (NSFC); Principal Investigator Denise Duarte (USP); Investment R$388,254.44.
Scientific articles
PRADO, H.A. et al. Designing nature to be a solution for climate change in cities: A meta-analysis – ScienceDirect. Science of the Total Environment. Oct. 8, 2024.
PARDAL, A. et al. Urbanisation on the coastline of the most populous and developed state of Brazil: the extent of coastal hardening and occupations in low-elevation zones. Anthropocene Coasts. June 26, 2024.
GOODWIN. S. et al. Global mapping of urban nature-based solutions for climate change adaptation. Nature Sustainability. Jan. 30, 2023.
BISHOP, M.J. et al. Complexity–biodiversity relationships on marine urban structures: reintroducing habitat heterogeneity through eco-engineering. Philosophical Transactions of the Royal Society B. June 27, 2022.
