Expected improved air quality

Phoenix is grappling with severe urban heat problems. As the city continues to grow, it is expected to experience a rise in temperatures of three to five degrees on average in the coming years. This makes urban heat a significant concern, especially for vulnerable populations. Phoenix’s extensive urban sprawl, combined with a lack of green space, has exacerbated the urban heat island effect, where cities become significantly hotter than surrounding rural areas due to the high concentration of concrete, asphalt, and infrastructure. In 2022, Nick Lodato, the principal of Emerson Elementary School, wanted to mark the school's 100th anniversary in a meaningful way. He decided that planting trees would be the perfect way to celebrate this milestone while also benefiting the community. The tree planting event not only symbolized the school's strong sense of community but also represented an investment in its sustainable future. Prior to the project, Emerson had only 9% tree canopy cover, which was far below what is necessary to address some of the pressing environmental challenges Phoenix faces.
Tree cover has become critical infrastructure for heat mitigation. Trees provide natural shade and help cool the environment by reducing surface temperatures, which in turn lowers energy consumption and promotes better public health. In addition to offering shade, the native, drought-tolerant trees and plants planted at Emerson will also contribute to carbon sequestration, purify the air, and improve mental health by creating more green spaces for relaxation and outdoor activities.
To complete this project, Emerson Elementary partnered with the Arizona Sustainability Alliance (ASA), a local nonprofit. Together, they planted over 100 trees and plants across the school’s campus, with approximately 125 people attending the event. Volunteers included students and their parents, Tau Psi Omega fraternity members, APS employees, neighbors, former Emerson students and teachers. (1-3)

The municipality of Ciudad Juarez, in collaboration with UN-Habitat, has drafted a redevelopment strategy for an area known as "Paso de Oñate." This intervention falls within the broader framework of "Vision Ciudad Juarez 2040." The plan involves constructing a forested green belt along the southern edge of the Rio Grande (/Bravo) in the northwest part of Juarez, bordering the USA.
Currently in the planning stage, the project aims to restore the ecological function of various degraded areas along the Rio Grande, transforming them into a continuous, green, walkable, and recreational space. The strategy includes allowing vegetation to recover, introducing native plant species, and increasing tree cover to rehabilitate unmaintained parks, derelict areas, and degraded riverbanks. These areas will be equipped with new features and integrated with existing parks, schools, and playgrounds. The envisioned green corridor will enhance walking conditions, improve the perception of safety, offer recreational opportunities for all age groups, and deliver valuable ecosystem services such as temperature regulation, improved air quality, and water retention.
In addition to its ecological goals, the project has a historical and geographical dimension. It aims to incorporate cultural heritage elements, such as the monument of the New Citizen, Paso de Oñate, Turtles Park, and the beginning of the Acequia Madre. It will also connect with other green space initiatives, including the Mega Park "El Chamizal" and the "Corredor Cultural," which runs through the city center.
This intervention is being prioritized due to the area's ongoing social and ecological decline. Paso de Oñate is a critical border crossing point, which negatively affects mobility and air quality. The area also suffers from a high concentration of vacant housing, which contributes to the residents' perception of insecurity. (Ref. 1, 2, 3, 4)

Maya’s Farm is a small, CSA (Community Supported Agriculture) sustainable urban farm located in Phoenix, Arizona, where urban development has limited farmland availability. In 2020 alone, Phoenix lost nearly 200 acres of farmland to urban sprawl, putting farms like Maya’s at risk. The farm faced potential closure until the City of Phoenix intervened, providing funding through the Farm Preservation Program, which established the city's first urban agricultural conservation easement. Maya's Farm strives to inspire a local appreciation for sustainable food and to bring renewed value to local food systems.
The farm’s mission is to provide accessible, fresh, locally grown produce to the community while promoting awareness of healthy, sustainable food practices. Through its CSA program, members receive a weekly produce box and have opportunities to come together, honor food traditions, and share stories over locally harvested food. As a CCOF (California Certified Organic Farmers) certified organic farm, Maya’s Farm is committed to organic practices that exclude GMOs, nurture the soil, foster biodiversity, and innovate growing systems. These methods result in healthy soil and cleaner air, contribute to carbon sequestration, and support critical wildlife habitats.
To broaden educational outreach, Maya’s Farm offers several programs that promote sustainable food practices, including its CSA program, an edible classroom series, and a partnership with Arizona State University (ASU). Through this ASU partnership, students gain hands-on experience by participating in daily farm operations.
Building stronger community connections is another cornerstone of Maya's Farm’s work. The farm collaborates with local restaurants, farmers' markets, and community groups to expand its impact. Maya’s Farm, ASU, and Arizona Sustainability Alliance launched an agrivoltaics project with solar-shaded crops. (2, 9, 11, 13, 15)

For a Forest in Your Neighborhood" is an afforestation campaign by the DDOR insurance group, launched in 2022 as part of their Environment, Society, and Governance (ESG) commitments (Ref. 1). Site selection was based on online votings, with thousands of votes being casted from 188 towns across Serbia (Ref. 2). In the end, the fifteen most popular cities were selected for project implementation. As a result, hundreds of trees were planted, including 25 trees along the promenade of Belgrade’s Ušće Park in 2023 (Ref. 3). Ultimately, the initiative aims to create and enhance urban green spaces, to improve air quality and living conditions in Serbian cities (Ref. 5). The success of the campaign encouraged DDOR to extend the campaign in 2024, financed through their eco-insurance schemes (Ref. 4)

The Urban Forestry Plan for Cartagena, led by EPA Cartagena, outlines a comprehensive strategy for enhancing the city's green infrastructure. The plan focuses on selecting suitable tree species, planting, and management to achieve several goals: reducing heat through shade, creating microclimates, protecting against climatic events such as coastal erosion and windstorms, enhancing food security, and enhancing the landscape's beauty. Over 10 years, the plan aims to establish at least 100,000 additional trees, increase overall tree cover, enhance accessibility to green spaces, and build a main ecological structure based on natural resources and biodiversity. It also emphasises the importance of local knowledge and resources (ref 1).
Formulated with community input, the plan commenced in 2013 and involved a detailed assessment of existing urban vegetation and climate conditions, utilising tools such as iTree. The development included international conferences and expert consultations to ensure a robust and informed approach (ref 1).

In the city of Ciudad Juárez, the municipality, in collaboration with UN-Habitat, aims to design and create a park that encompasses the yards and unmaintained areas surrounding the railway station, transforming these spaces into an accessible and safe public area. This project covers over 500,000 square meters and addresses not only degraded areas but also several public squares. Described as "a coordinated urban recycling strategy," this initiative seeks to repurpose existing public squares and rehabilitate neglected spaces into vibrant green areas that feature universal accessibility, native vegetation, and urban furniture designed to enhance safety. The project also aims to provide increased recreational opportunities, improve permeability, and introduce additional shaded areas. A key component of improving permeability involves the restoration and incorporation of acequias—traditional historical irrigation systems that absorb and manage excess rainwater, thereby reducing the likelihood of flash floods.
Additionally, the project focuses on the restoration and promotion of significant historical buildings, such as the old railway station and the whiskey factory, integrating them into a larger cultural and sports facility area at the municipal scale. The overarching goal is to revitalize the site through effective coordination with the relevant authorities responsible for the spaces adjacent to the railway station, stretching from Plaza Misión de Guadalupe to Blvd. Municipio Libre. This collaborative effort aims to accommodate both sports and cultural facilities while also creating a green corridor.
Furthermore, the project intends to reforest, redesign, and enhance Plaza Misión de Guadalupe, Plaza Monumento a Benito Juárez, and other residual public spaces and gardens. This initiative aligns with its Public Space Strategy, which emphasizes the development of gender-inclusive and resilient public spaces.(Ref 1, 3, 4).

The Silk District is a real estate project by Prime Kapital in partnership with MAS P.L.C., integrating green spaces into its urban design (1-10). It focuses on regenerating a brownfield site, an abandoned industrial area left undeveloped in one of Iasi's neighborhoods (1). The project aims to revitalize the area, improving its aesthetics, reducing pollution, and repurposing it into a commercial and residential space (1). A key feature of the project is the incorporation of green spaces throughout its design (1).
The development spans 101,000 square meters, with 40,500 square meters (combined) dedicated to green spaces and "car-free" open areas (1, 2, 6, p.2). These green elements are designed to offer spaces for relaxation, recreation, and social interaction, while also contributing to environmental benefits such as air filtration, temperature regulation, rainwater drainage, and soil erosion prevention, all promoting better health for residents (1, 2, 4, 6, p.12). The landscape design includes “green islands” and vegetation-covered roofs for parking structures (4).
Launched in 2021 after receiving municipal approval, the project is ongoing and has already made significant progress, with over 10,000 perennial plants and 401 trees planted (4, 9). Upon completion, the landscape will feature 7,100 square meters of perennials, 3,000 square meters of shrubs, and an urban forest containing 2,400 trees (6, p.12).
The total investment in the project is €20,000,000 (7). In 2024, one of the completed office buildings earned a BREEAM green certification, achieving one of the highest possible scores, in collaboration with the consulting firm BuildGreen (5, 8). The landscape design was carried out by the architectural firm Beros Abdul+ (4). Before receiving approval, the project was opened for public consultation, and an independent online survey showed strong support from the community (15, 16).

Tempelhofer Feld stands as an innovative green solution in the heart of Berlin, addressing several issues of environmental justice, biodiversity, and urban resilience. Within the S-Bahn ring, only one in 20 residents lives in areas well-served by green spaces, and districts like Neukölln, Kreuzberg, and Tempelhof would face even greater scarcity without this vast expanse. Many residents in these neighborhoods lack access to private green spaces such as gardens or balconies. Without nearby parks, people are compelled to travel to other districts, exacerbating the congestion of green spaces and increasing local traffic.
Since its opening in 2010, Tempelhofer Feld has provided Berlin with over 300 hectares of open, green, leisure, and recreational space, making it one of the largest urban open spaces globally. Once the site of bustling air traffic, it is now a sanctuary for activities such as skating, strolling, gardening, picnicking, birdwatching, kiteboarding, and more. These wide-ranging uses showcase its transformation into an accessible, multifunctional green space that serves as a social equalizer, particularly for disadvantaged neighborhoods, a significance amplified during the Covid-19 pandemic.
The field is not just a recreational haven but also a vital ecological refuge. With over two-thirds of its area designated as green space, it hosts diverse ecosystems, including extensive natural meadows, lawns, and protected habitats for birds and other species. Certain areas are closed to the public to preserve these sensitive environments, emphasizing the balance between human activity and ecological conservation. Since 2019, animal landscape keepers, including around 100 resident sheep, have contributed to sustainable land management practices, promoting biodiversity and ecological health (Ref. 2).
Managed collaboratively by political, administrative, and societal actors, the site exemplifies integrated citizen participation in urban planning. (Ref. 3)

The "Line Park" project in Belgrade aims to create a continuous green belt spanning 4.6 kilometres and covering over 48 hectares. As such, the project will revitalize the former railway corridor from "Beton Hala", just below the Belgrade Fortress, to the Pancevac Bridge. Inspired by notable urban parks like New York's "High Line", Moscow's "Zagrađe," and Toronto's "Rail Corridor," it will become a major recreational destination and also help to alleviate the pressures from the city's heavy air pollution and summer heat (Ref. 5, 6).
The park will be divided into ten thematic sections dedicated to aromatic plant and flower gardens, urban gardening and beekeeping, sports facilities, a newly built university campus and more. Additionally, there will be an amphitheatre and facilities for outdoor education. To further integrate green infrastructure, new buildings will have green roofs and walls (Ref. 2,5). Ultimately, the park integrates a number of amenities into the entire city.
The development of the park also introduced innovative co-creation mechanisms in terms of governance and planning. Since Belgrade is part of the multinational CLEVER Cities Initiative, the city's Secretariat for Environmental Protection suggested the use of the site as a pilot test for introducing nature-based solutions in urban planning and with diverse stakeholders' input. Several workshops, focus groups, and consultations took place between 2019 and 2021, which facilitated the diversity of ideas that have been adopted into the official construction plan (Ref. 1, 2). Despite these successes, civil society groups raise concerns over the extraordinary cost of 70 million euros, displacement of Roma communities and the interest of real estate developers that may undermine the project's original cause (Ref. 3, 8).

The "Ruas Verdes+" (green streets) project, implemented in the parishes of Areeiro and Arroios in Lisbon, is part of a broader European initiative, Conexus, aimed at promoting green solutions in highly urbanized areas (Ref 3). The project primarily focuses on creating a tree-lined pedestrian corridor along Carlos Mardel and Francisco Sanches streets, establishing a continuous axis between the Casal Vistoso Urban Park and the Caracol da Penha Garden (Ref 1). This corridor is designed to mitigate urban heat island effects, enhance ecological connectivity, and improve residents' quality of life (Ref 5). The pilot phase includes planting 20 trees on Rua Carlos Mardel and removing a minimal number of parking spaces to balance urban greening with local needs (Ref 1). Additionally, planters are being introduced in the Bairro dos Actores area to test the community’s response to greening initiatives (Ref 1). The project also involves public participation through gardening workshops, encouraging residents to contribute to the greening effort by adding plants to their balconies (Ref 4). This initiative aims not only to enhance the urban environment but also to foster social inclusion and community engagement while addressing the challenges of climate change in Lisbon's densely populated areas (Ref 5).