Climate-Related Hazards

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].

In the bay of Fort-de-France, mangroves cover nearly 1,300 hectares, representing about 70% of the total mangrove area in Martinique. This plant formation, characteristic of tropical marine environments, is essential for the ecological balance of the bay. Mangroves act as filters, purifying marine and river waters, protecting the coastline against erosion, and providing habitat for various marine flora and fauna.
However, this fragile ecosystem is threatened by wave-induced erosion, urbanization, the spread of invasive species, and pollution. In response to these challenges, the French Coastal Protection Agency (Conservatoire de l'espace littoral et des rivages lacustres, CELRL) and its partners have launched an initiative to restore several mangrove areas as part of the “Contrat de la Grande Baie de Martinique" which is a collaborative initiative aimed at the sustainable management and restoration of the coastal and marine environment of the Greater Bay of Martinique. This contract typically involves partnerships between various stakeholders, including government agencies, local municipalities, environmental organizations, and community groups. The project identified several sites totaling 3.81 hectares in the Greater Bay area that require reclamation.
The project aims to restore mangrove populations by creating favorable conditions through actions such as clearing invasive species and trash, followed by replanting with white, black, or red mangrove seedlings, depending on the environmental characteristics of each site. Additionally, the initiative seeks to engage the public and youth through volunteering days and awareness campaigns (Refs 1-9).

The Ringsend Open-Air Laboratory project in Dublin, Ireland, is part of a broader effort to adapt urban areas to increasing climate change risks. This initiative focuses on installing green roofs and deploying a network of environmental sensors to enhance urban resilience. Launched in 2018 under the Horizon 2020 OPERANDUM project, the effort seeks to find nature-based solutions for climate change impacts worldwide. Led by the University of Bologna, OPERANDUM involves over 20 partners, primarily in Europe, working together to address environmental challenges like flooding, drought, and coastal erosion through the establishment of ten "Open Air Laboratories" globally.
In Dublin, the project aims to bolster flood resilience in Ringsend, a critical economic area near the city’s tech district, which faces substantial flood risks due to its low elevation and proximity to the Dodder River. This river, which flows through both rural and urban areas before meeting the River Liffey near Ringsend, has caused property and infrastructure damage from extreme rainfall and combined river and tidal flooding.
Green roofs play a key role in mitigating urban flood risks in this project. These rooftop gardens absorb large volumes of rainfall before it reaches the streets, easing the load on existing flood prevention systems like storm drains and gullies and reducing the need for additional "grey" infrastructure. Based on community insights and recommendations, construction has begun on a green roof on top of the CHQ building in Dublin’s Docklands, in partnership with Dogpatch Labs.Complementing this, over 100 sensors have been deployed in recent research trials across Dublin. OPERANDUM researchers are now building on this foundation to create a denser, more reliable, and cost-effective sensor network, with data from earlier low-cost sensor trials made publicly accessible via Dublinked, Dublin’s open data platform, and exploring the use of LPWAN for environmental sensing. (1-5, 7)

Torslanda School is a newly built elementary school (years 0-6) where the schoolyard includes innovative ways to manage rainwater. The school was initially part of the Rain Gothenburg project, which aims to make the city, and this school, the best in the world when it rains. It was also a pilot project within the city's "equal building" initiative, aiming to make indoor and outdoor environments accessible and attractive to everyone regardless of gender identity, functional diversity or age [Ref. 1]. The main element of the schoolyard is a "river" to which water will be led when it rains, combining stormwater management with opportunities for play and education. The system will retain about 310 m3 of water and treat it before releasing it to a recipient. The river will be used to teach the children about climate, ecology, biodiversity and the water cycle. The river and schoolyard are connected to a natural wetland [Ref. 3, 4]. The school is run by the City of Gothenburg, who initiated the project, employing an architecture firm and a construction company to design and build the school and schoolyard [Ref. 3-5].

The "Mangle Verde" project is a community-led intervention aimed at reforesting mangrove areas in Cartagena, particularly around the Ciénaga de la Virgen and Ciénaga de Juan Polo. Initiated by Gloria Sánchez and other members of the Villa Gloria community, this project is a response to the environmental degradation caused by urban development, including the construction of a viaduct, and the damages inflicted by invasive settlements and pollution​(ref 1,4). The primary goal of the project is to restore the mangrove ecosystems, which are essential for maintaining water quality, preventing coastal erosion and supporting marine biodiversity conservation (ref 4). In addition, this initiative provides socio-economic benefits by fostering ecotourism and increasing fish populations, which directly benefit the local fishing economy​(ref 1). The "Mangle Verde" project emerged as a grassroots response to compensations granted by the Concesión Costera for the damage caused by infrastructure projects in the region. Local residents of Villa Gloria, recognizing the importance of the mangrove ecosystem, established nurseries in their homes where they cultivate three types of mangroves (ref 2,4). So far, the initiative has planted over 26,860 mangrove saplings and is committed to continuing the reforestation efforts, which also include cleaning and maintaining the canals around the mangroves​ (ref 1). Beyond ecological restoration, the project also addresses key environmental risks in Cartagena, including coastal flooding and habitat degradation, driven by both natural phenomena (e.g., tides) and human activities such as urban sprawl and illegal dumping (ref 6, 7).

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 Institute of Physics at Humboldt University of Berlin is an outstanding example of ecological urban development and a global pilot project integrating rainwater management with building cooling through greening. A key feature is the cooling system, which relies on air circulation processes supported by green roofs, facades, and an artificial wetland/pond incorporated into the building's exterior and courtyard.
Rainwater is collected in cisterns and used to irrigate the green façade, enabling evaporative cooling in air conditioning systems. Excess water is either evaporated in the inner courtyard through a pond or allowed to seep away. (Ref. 1; Ref. 4) The greening of the façade is directly linked to energy optimization. During summer, the green façade provides solar shading against extreme heat, while in winter, sunlight passes unobstructed through the glass façade. Additionally, evaporative cooling improves the microclimate inside the building and its surroundings. (Ref. 3)
Berlin, as a densely built city, faces challenges like urban heat and high energy demands for cooling. This project offers a research-driven solution. Monitoring measures water usage for various plants, evaluates evaporative cooling effects, and assesses impacts on the building's energy balance and overall economic and ecological performance. The findings aim to create a foundation for the long-term implementation of innovative, cost-effective technologies. This process is conducted by multiple regional universities. (Ref. 1)
The project was initiated and financed by the state of Berlin and implemented after the building's construction. (Ref. 4; Ref. 5) It serves as a benchmark for sustainable urban development and a research model for similar initiatives worldwide.

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).