Improved air quality

Martinique is a biodiversity hotspot, home to over 1,500 endemic plants, 70% of which are under threat from human activities. In response to these pressures, the Péyi Vert [Green Country] initiative was launched to plant endemic trees and strengthen the island's biodiversity. Beyond simply preserving species, these trees are crucial in maintaining healthy ecosystems, as they provide essential services such as carbon sequestration, shade, food for human consumption, soil decontamination, pollination, and protection against coastline erosion.
Launched in June 2020 by Entreprises et Environnement (EE), a not-for-profit business association representing 80 Martinican companies, the Péyi Vert initiative aims to plant 1 million native trees (either Martinican or Caribbean) over five years. It can be seen as a Martinique-wide strategy to adapt to and mitigate climate change. Péyi Vert facilitates connections between people who want to plant trees and Martinican companies that serve as financial sponsors. The initiative emphasizes conserving natural heritage by planting endangered species, as well as promoting native species that, while not necessarily threatened, provide valuable ecosystem services or contribute to biodiversity restoration.
Between 2020 and 2023, EE reported planting 50,000 trees (Refs 1, 4, 6, 7). Although individuals can make donations, Péyi Vert primarily seeks funding from companies looking to offset their carbon emissions or enhance their Corporate Social Responsibility (CSR). To achieve its goals, the initiative mainly collaborates with municipalities, companies, and farmers (Ref 3).

Rainwater management in Gdańsk presents significant challenges due to the city's hydromorphological conditions, including high groundwater levels and steep terrain. These factors, coupled with the periodic inefficiency of the storm sewer system and the intensification of extreme weather events such as heavy rainfall, have necessitated innovative solutions. Gdańsk has responded by implementing a climate change adaptation policy that promotes the use of open drainage systems, including small retention facilities like rain gardens. These gardens help mitigate the risks associated with excessive rainfall while enhancing urban sustainability.
The first rain garden in Gdańsk was established in the Stogi district at the Flood Control Warehouse on Kaczeńce Street. This facility collects and utilizes rainwater from nearby paved surfaces, aiming to manage rainfall of at least 30 mm during intense, short-term downpours. Utilizing a variety of perennials such as marsh marigold, common loosestrife, comfrey, hemp agrimony, common calamus, and arrowhead, the garden retains and filters rainwater naturally, increasing efficiency and ecological benefits. Rain gardens absorb water up to 40% better than traditional lawns. They reduce rainwater runoff, mitigate flood risks, filter pollutants, improve biodiversity, and enhance urban air quality while lowering temperatures.
The garden was created as part of a broader investment in the Flood Control Warehouse in Stogi, a facility opened in 2017 at a cost of over PLN 5 million. Strategically located near the Sucharski Route and the Martwa Wisła tunnel, the warehouse supports rapid response to flood emergencies, storing over 100 types of equipment, from shovels to large generators. This combination of infrastructure and green solutions demonstrates Gdańsk's commitment to urban resilience and environmental sustainability. (1-4)

The Torre Sevilla is a commercial building complex with extensive green roofs. The green roofs cover 11000 or 12000 m2 (different sources report different numbers) and aim to contribute to thermal isolation and energy efficiency of the building, improve air quality and provide an urban green space for relaxation and recreation [Ref. 1-3]. The green roofs include a mosaic of different vegetation types and about 60 mostly native plant species. There is a rainwater recovery system that allows the gardens to be irrigated in a sustainable way [Ref. 1-3, 6]. The building finished construction in 2017 and the gardens were initially not available to the public. In 2023, the owner applied for a permit to host events in the gardens, which will allow the public to visit on occasion [Ref. 1, 3-5].

Alexandria is one of the world’s most climate-vulnerable cities, facing serious environmental challenges that threaten its landscape, culture, and livability. The city is grappling with rising sea levels, pollution, extreme fluctuations in temperature, and the intensifying urban heat island effect, all of which are worsened by climate change. The past decade has seen a steady decline in Alexandria’s parks and green areas, a trend that has raised significant concerns among environmentalists and the public. The shrinking green spaces are largely due to rapid urban expansion and the development of commercial projects, which are gradually pushing Alexandria's environmental balance and cultural heritage to the edge.
In recognition of these pressing issues, Egypt launched the "100 Million Trees Initiative" in 2022 as part of its Egypt Vision 2030, a national plan for sustainable development. The initiative aims to increase the per capita share of green space throughout the country, with objectives that include improving air quality, enhancing public health, countering the urban heat island effect, and reducing greenhouse gases. The initiative is also focused on improving the beauty and cultural value of Egypt's urban areas, aligning with broader goals to build sustainable and climate-resilient cities. Alexandria, being a coastal city that is both environmentally sensitive and culturally significant, has been a focal point of these efforts.
As part of this national campaign, the Governor of Alexandria was tasked with overseeing the enhancement and expansion of green spaces across the city, focusing on both the aesthetics and cultural aspects of the urban landscape. In 2023, these efforts took root in the Al-Muntazah 2 neighborhood, where 596 trees were planted as a contribution to the 100 Million Trees Initiative. This project included the Al-Samad Preparatory and Secondary Schools campus as one of its primary planting sites. (1-5)

The initiative consists of an afforestation campaign promoted by the local government of La Paz, with the objective of planting 10,000 trees and shrubs (1 & 2). Carried out between 2023 and 2024, the campaign included plantations across all the macrodistricts of La Paz (1). To ensure the campaign's success, the municipality encouraged the participation of volunteers from various institutions, such as public services, environmental groups, schools and universities, neighborhood associations, church groups, and even Army and Navy units (1 & 2). The trees play specific roles in mitigating climate change, improving air quality, reducing odors from nearby landfills, and decreasing the risk of landslides and soil erosion (3 & 4). Furthermore, the campaign aims to foster environmental awareness among citizens and replace trees lost due to illegal deforestation (1).

The species selected for planting were provided by EMAVERDE, the public company responsible for managing green spaces in the city. The selection included primarily native species, along with a few introduced ones, all chosen for their resilience to La Paz's varying climate conditions (1, 2 & 4). Given the challenging climate and difficult soil conditions, the municipality informed volunteers about the importance of maintaining the saplings, particularly during drought periods, to ensure their proper growth (1 & 2). The campaign also supported the municipality’s urban development plan (Plan Territorial de Desarrollo Integral "Para Vivir Bien") and the "Plan Integral de Recuperación de la Tormenta a la Esperanza," the latter developed in response to extreme rain events and floods that occurred during the campaign months (5).

The Alexandria Governorate is especially susceptible to the impacts of climate change, a vulnerability exacerbated by its dense coastal communities and rapidly growing population (2). Both demographic shifts and urban development intensify how climate phenomena affect the people and infrastructure of Alexandria (1). Buildings, roads, and other concrete structures absorb and release solar heat, significantly contributing to the urban heat island effect, which is causing temperatures in the city to rise faster than in less developed areas (1). Despite Alexandria’s growing need for cooling green spaces, they currently make up only 0.25 percent of the total area within the Governorate, highlighting an urgent need for environmental interventions (3-6).
In response, Ahmed Gaber, chairman of the Alexandria Water Company, initiated a public awareness campaign in 2023 focused on the numerous benefits of planting green roofs (3-6). Green roofs serve multiple purposes: they extend the longevity of buildings, lower energy consumption, improve air quality, increase biodiversity, manage rainwater runoff, and mitigate the urban heat island effect (3). Furthermore, Gaber has emphasized the visual appeal of eco-friendly roofs, noting that green roofs offer an aesthetically pleasing option that enhances the urban landscape while serving critical environmental functions (4).
This initiative by the Alexandria Water Company marks a pioneering step among governmental organizations in the region, as they lead efforts to address climate and environmental challenges actively. The company has begun planting green roofs across its facilities, including the new Al-Mashishya water station, where green spaces atop buildings are set to bring lasting environmental benefits to Alexandria. Through these efforts, the Alexandria Water Company is working to set an example for public and private sectors alike (3-6).

Alexandria is a city with a special charm, known for its beaches and gardens that act as the lungs through which the city breathes, and are considered a haven for its people (1). Unfortunately, in the last ten years, there has been a decrease in green space due to urban expansion and the establishment of Commercial and profitable projects (1). To address the lack of green space in the city, The Governor of Alexandria has stressed the continued efforts to develop, beautify and plant the squares and turn them into attractive civilized facades, as part of Egypts 2030 vision which aims to move towards a greener city and reduce the effects of climate change. (2). To encourage redevelopment of public green spaces, The Governor launched the “Alexandria shines with its squares” competition in 2023, where the top three neighborhoods with the best redeveloped squares would receive a prize of up to EGP 50,000 [928.45 EUR] (6). The First Al Montazah neighborhood participated in the competition by redeveloping Sidi Bishr Mosque Square (2-5). The 700 meter square was completely upgraded with solar energy, a new irrigation system to conserve water, modifications to the sewer network, and planting the garden with plants that suit the environment (3). The greening activities included planting 400 sticks of various crops in the upgraded square (4).

To protect the Lomas de Primavera from urban pressure and other threats, the Lomas de Primavera Ecological Association has implemented strategies for its conservation. One of the strategies this organisation has promoted is reforestation activities. Working together with the Municipality of Lima and other interested actors, they have sought to expand Lima's green spaces, improve air quality, enhance flora, and promote tourism, among other benefits (1). Lima's Municipality has supported the project by donating 20,000 trees for reforestation and to prevent land encroachment (1), social organisations and environmental activists have joint efforts to plant more than 250 trees to support the conservation efforts (2, 7).
The Lomas de Primavera Ecological Association leads the project, organizing community management efforts to conserve the Lomas de Primavera sector. This association is based in the Agrupación Familiar Primavera Lomas de Carabayllo community (2). The association's conservation activities involve collaboration with various stakeholders at different levels. Locally, it works with community leaders and organizations. At the district level, it coordinates with the Carabayllo municipality and the NGO CIDAP to improve urban conditions. The metropolitan-level collaboration includes the Municipality of Lima and the ACR 'Sistema de Lomas de Lima' for ecosystem protection and valorization. Nationally, it partners with MINAM, SERNANP, MINAGRI, UNDP, UCV, and the Network of Peruvian Lomas to enhance ecosystem services, restore degraded areas, and conduct research on the Lomas (2).
The preservation and reforestation of these ecosystems is essential, as they have social, cultural and environmental value, including the following ecosystem services: provision of genetic resources, soil formation, pollination, aesthetic services, ecotourism, food, education, and archaeological and historical services (3)

In 2020, the European Fund for the Balkans (EFB) launched the Trees of Friendship project, which plants over 400 trees annually across six Western Balkan capitals, known to be some of the most air-polluted cities in Europe (Ref. 5). Tirana has been involved from the start, having planted over 110 trees in locations such as Great Lake Park in 2020 and Farka Park in 2022 (Ref. 1,2).
The project is carried out with the support of local municipal and civil society partners, including Tirana's Parks and Recreation Agency and the Environmental Territorial Management Institute, along with activists and volunteers (Ref. 1,2). The initiative was planned in 2019 when the EFB board decided to mitigate its CO2 emissions from business-related flights and enhance local and regional cooperation on air pollution (Ref. 3,4,5). Despite challenges in citizen engagement during the COVID-19 pandemic, the Trees of Friendship project continues to raise awareness about the role of trees in mitigating the impact of air pollution on health and well-being (Ref. 2). Its strong and well-established local and regional partnerships have facilitated the project's implementation in the past and continue to benefit in scaling the project (Ref. 1,5).

In 2001, the local municipality of La Paz, in collaboration with the International Union of Architects (UIA), launched a design contest to create a central park within a protected natural area (3). The park's aim was to develop urban infrastructure while connecting nature with the city (3). The winning architectural design envisioned an infrastructure that would harmonize with the existing natural surroundings and minimize interference with the environment (4).
The park's implementation included pedestrian and bike pathways, numerous panoramic viewpoints, facilities for exercise and cultural events, buildings dedicated to science, historically significant monuments, playgrounds, and the rehabilitation and creation of multiple green spaces (1 & 4 to 6).
While most of the project was completed by 2009, the area's exposure to recurrent landslides, droughts, and illegal waste disposal, combined with ongoing degradation, has necessitated afforestation efforts and maintenance actions from the municipality to ensure the protection of the natural area and enhance its benefits (7 & 8). Recently, the park has been part of a national citizen monitoring program for species, which has improved the categorization of wildlife in the area (11 & 12). Additionally, 2,000 trees were planted in the park in 2023 as part of a reforestation campaign, and cleaning and watering maintenance work has been carried out to support their growth (7 & 13). This initiative is part of a larger project to revitalize the park (10 & 13).
Overall, the park aims to protect local wildlife and plant species while acting as a "green lung" for the city, regulating the climate, providing recreational spaces, and improving livability (14).