Climate change mitigation

Around 90% of Guyana’s population lives in an area that is below sea level, with many inhabiting flood-prone areas along the coast. The coastal plains are also home to about 75% of the country’s economic activities, including almost all of Guyana’s agricultural production. Over the years, degradation and loss of mangrove forests have resulted in increased coastal flooding and saltwater inundation of agricultural land. Mangroves contribute substantially to sea defence in Guyana by damping wave action and reducing wave energy, trapping sediments and stabilizing shoreline substrates while playing an important role in carbon sequestration.
The Guyana Mangrove Restoration Project was executed during 2010-2013 under the National Agricultural Research & Extension Institute. Following completion of the Project phase and given the importance of mangroves to Guyana’s coastal defences, mangrove restoration and management were integrated into NAREI (the National Agricultural Research and Extension Institute), a national institution that promotes climate-smart agriculture and resilient citizens. (1,2)

The Democratic Republic of the Congo’s coastal zone stretches 40 km and comprises the towns of Muanda, Banana and Nsiamfumu. The problem of coastal erosion has intensified since 1980 with the significant retreat of the coast in the Banana-Muanda segment, this retreat has been estimated as much as 2,300 meters. According to the report of the second national communication on climate change (2010), the Democratic Republic of Congo’s coastal zone, with a coastline of about 40km, is facing coastal erosion due to a combined effect of topography, sandy nature of the soil and ocean dynamics (height and direction of the swell, tide height, current velocity, storms etc.). With the rate of shoreline retreat that is likely, it is expected that the road between Banana-Muanda will be completely lost between 2050 and 2100. The proportion of lands lost to encroaching sea will double (200 m around Nsiamfumu and 100 m between Muanda city and Banana). In total, DRC can expect to see the reach of its coastal zone reduced from 50-100 m by 2100. To respond to some of these complex challenges the Department of Environment, Nature Conservation and Tourism, Democratic Republic of Congo implemented the present intervention partnering with the United Nations Development Programme (UNDP) and the Global Environment Facility (GEF). (1,2)

Douala is the economic capital of Cameroon and one of its largest cities. The city is located on the banks of the Wouri River (hence a port city) and its climate is tropical. The marine and coastal biodiversity of Cameroon is rich and diverse, and it is highly endangered because of human activities including artisanal and industrial fishing and pollution generated from industries, accidental loss of crude oil in transit or during loading or unloading. In Douala, thousands of inhabitants have settled in and around the mangrove swamps, destroying the mangrove ecosystem and endangering biodiversity including snakes, birds, fish, trees and frogs. Biodiversity studies are rare, and even if they exist, they are done in part and do not give an overview of the real state of biodiversity in the city. The city of Douala is full of many ecosystems of various natures (micro-ecosystems), each of which has species adapted to the environment. Besides this, Douala confronts itself with seasonal flooding and high temperatures due to climate change. In response to some of these challenges, a local entity, the Association of academics and researchers for Biodiversity conservation, initiated in 2020 an action that focused on environmental education and biodiversity conservation. The initiative also provides a framework for reflection and exchange on biodiversity issues. (1,3,4)

In 2019, in the city of Ulan-Ude, the most comprehensive and large-scale action "Green City" was launched [2,3,4,5,12], with the goal of creating an efficient and sustainable greening system in Ulan-Ude [1,7]. Nowadays, according to the city's norms, there are two times fewer green spaces per resident than is customary [7]. According to this program, by 2024, the provision of the population with public green spaces should be 10 sq. m per person [1,8]. Within the framework of the project, effective technologies for greening are already being introduced, and all green spaces growing in the city are being monitored [3,5,6]. Planting of green spaces is carried out under the guidance of the Scientific and Technical Council for the Integrated Greening of the City, which includes Buryat scientists and specialists from the City Administration [2].

Ecuador is considered one of the most biodiverse countries in the world (one of the 17th most diverse), due to the high diversity of their natural species. The country has around 23.056 taxonomic species of animals and plants reported, which constitutes the 6,1% of all species reported worldwide. (6) Quito, the country's capital makes no exception and is considered a biodiversity hotspot. In recent years, urban expansion has had a detrimental effect on the environment and the city’s ecology. All of these actions exacerbate the stresses on the different ecosystems, contaminate water sources and networks, and put the city’s capacity to supply ecosystem services at risk. To respond to many of these challenges the municipality of Quito initiated in 2020 a nature-based solution program under the EU framework of Clever Cities. (1) The project intends to position nature-based solutions as a means to improving public health, social cohesion, citizen security and increasing economic opportunities in those areas. (3)

The Anderson Road Quarry, once a vacant 40-hectare site is getting transformed into a sustainable residential neighbourhood while ensuring climate resiliency and low environmental impact in Hong Kong. The site will supply housing for 25,000 people. In addition to this, the city is employing a wide array of adaptive and resilient approaches including saving around 3,000 metric tons of CO2 annually, helping the city live up to its 65% to 75% carbon reduction goal by 2030 set in Hong Kong Climate Action Plan. [1]

As a result of a ReefFix Project, an Integrated Coastal Zone Management (ICZM) Coral Reef and Mangrove Restoration and Watershed Management Demonstration programme, the Three Bays Marine Protected Area (MPA) and associated Integrated Coastal Zone Management (ICZM) Plan have been established in Haiti (Refs. 4, 5 and 7). Only the second MPA to be established in the country, the Three Bays MPA includes the bays of Limonade, Caracol and Ft. Liberté (the administrative capital of the Nord-East department of Haiti), as well as the Lagon aux Boeufs. As summarised by Ref. 8, the establishment of the MPA and ICZM "will help protect the mangroves, eel grass beds, reefs and habitats housing important fisheries that are crucial for providing livelihoods to nearby communities. It will also help protect the area from storm surges and provide local communities with ecosystem services such as carbon sequestration, tourism value and more". Additionally, the MPA will afford protection to numerous threatened species, "including sea turtles, whales, manatees and migratory birds" (Ref. 8).

Medellin is the second-largest city in Colombia. The city used to be one of the most dangerous in the world, as Pablo Escobar founded here the Medellin cartel. After the death of Escobar, the city's homicide rate has decreased by 95% and extreme poverty by 66%, thanks in part to a string of innovative mayors who laid out plans to integrate the poorest and most violent hillside neighbourhoods into the city centre in the valley below. The same innovative mayors realised that Columbia and its cities are very vulnerable to climate change being located in a tropical zone and is influenced by El Niño and the La Niña. In Medellin, the municipality has built upon a tradition of planning to become an urban lab for the construction of public life with the aim of inclusive, peaceful and sustainable development. As such starting in 2008 Medellin began implementing a green strategy whose goal was the creation of a green belt around the city as well as waste control. The intervention discussed in this case is one initiated in 2014 when the municipality carried out planting and reforestation projects for the protection of the eastern slopes of the city. (1,2,3)

Touted as a long-term solution to flooding of Mandaue City, establishment of a mangrove eco-park has begun, having received funding from the Department of Budget and Management (DBM) (Ref. 1). Through establishment of mangroves, the eco-park will "perform a significant role in shoreline protection, acting as a buffer against strong winds and waves", which is considered particularly important in light of the anticipated effects of climate change (Ref. 6).

A total 17-hectare plot is to be rehabilitated, as identified in the Mandaue City Government's Comprehensive Land Use Plan (Ref. 3). At present, it is unclear whether nature-based solutions (including mangrove restoration) are to be implemented across the entire 17ha of the site, but initial efforts have been focused on the restoration of a 5-ha section of mangrove forest (Ref. 2). Due to the lack of data on how exactly the remainder of the 17-ha area will be restored, the total NBS area for this project has only been recorded as 5-ha (5000m2) within this case study, rather than the entire 17,000m2 which is encompassed within the site.

The site is situated at the outfall of the Butuanon River which frequently overtops as a result of heavy rain and has been considered "biologically dead" since 1992 (Ref. 7). The site itself comprises a former dumpsite which had been "left derelict and filled with piles of trash", hence in addition to reducing flood risk, its rehabilitation will serve as green space in which "the residents of Mandaue City [can] gather and enjoy a breath of fresh air" (Ref. 2). The eco-park is considered to bring the added benefit of filtering water as it enters the Mactan Channel, in addition to reducing greenhouse gas emissions through carbon dioxide absorption (Refs. 1 & 6).

The Porsuk Stream divides the city of Eskişehir into two with a green corridor running along the shores of the stream. The Porsuk Stream served provisioning services and acted as a recreational area in the first half of the 20th century, however with increased industrial activities discharging untreated wastewater into the river, rapid urbanisation in the city and other settlements, and increased fertilisers and pesticides in the groundwater originated from agricultural practices (upstream of the Porsuk River), it became highly polluted and its ecosystem degraded severely (1,2,4,5). The Organization for Security and Cooperation in Europe (OSCE) identified the stream as one of the highly dangerous rivers in terms of pollution and health, where no living beings except viruses live (1).
Within the framework of the 'Eskişehir Urban Development Project' the 'Natural Disaster Loss Reduction Project (Porsuk Project)' has been initiated focusing on the ecological restoration of the stream, improving water quality, increasing the resilience of the city against natural disasters (as earthquakes and floods) while also reestablishing the stream's environmental and social role in the city (1). A network of natural infrastructure was created along the Porsuk by expanding public green spaces and link the entire corridor with a sustainable public transport network. (4,5)