Case study

Barcelona: Nature-based Solutions (NbS) Enhancing Resilience to Climate Change

An elevated view across Barcelona.
Start/end date:

p>Figure 1 Barcelona seen from the Collserola Park. Source: City of Barcelona.

 

Challenges

Barcelona is highly populated and one of the busiest tourist destinations in Europe. In 2012, the city fell well short of the European Union’s recommendation on access to green space (6.82 m2 per capita compared to the 26 m2 per capita target recommended by the EU (Laghai, 2012)).

Air quality in Barcelona is poor. It is estimated that 3500 lives could be saved annually in Barcelona by reducing current levels of air pollution to meet WHO standards (Künzli and Pérez, 2007).

The city is also facing rising temperatures as a consequence of climate change, leading to extreme weather events, such as droughts and heat waves.

Barcelona is geographically delineated by the sea to the east, the Collserola hills to the west and two rivers (Besòs and Llobregat) to the north and south. These mountain and river ecosystems have been the subject of restoration interventions. They act as natural borders between municipalities, so managing them requires a supra-municipal approach.

Population density is high and there is a lack of space for urban expansion, with the urban areas extending to neighbouring municipalities (with up to 5 million inhabitants sharing the same infrastructure).

Objectives

The City of Barcelona, with its Green Infrastructure and Biodiversity Plan up to 2020 (City of Barcelona, 2013) is implementing a range of actions to bring nature into the city. The main objectives are to preserve and improve the natural heritage of the city and to conserve its biodiversity. This would ultimately bring environmental and social benefits for local people.

With a similar vision, but with different solutions, the Trees Master Plan 2016-2035 has the overall aim of maintaining a well-managed, healthy and biodiverse woodland to improve green corridors and tackle the urban heat island effect.

Actions

Actions such as the further development of urban green corridors help to increase connectivity between green areas. In particular, the city recognises urban vegetable gardens as an important component of an urban green infrastructure.

A network of street trees is also helping to boost resilience and adaptation to climate change, providing direct benefits to urban people.

To the south of the metropolitan area, the coastal zone includes the delicate ecosystem of the dunes, which is managed by the Metropolitan Administration and provides ecosystem-based adaptation. The peri-urban forest of Collserola, in turn, is managed by the Consorci del Parc Natural de Collserola so as to provide a series of ecosystem services.

While these measures have been planned separately at different times, taken together, they can be seen to have clearly enabled synergies in tackling a series of social challenges by providing key ecosystem services.

Thus, even if not explicitly following a systemic NbS approach from the outset, the cumulative effect of these measures is greater than merely a series of individual projects.

Objectives /Theme

Objectives /Theme

Solutions/Measures		 Enhancing sustainable urbanisation Restoring ecosystems and their functions Developing climate change mitigation Developing climate change adaptation; Improving risk management and resilience Main ecosystem-based approach applied
Street trees Enhancing city attractiveness and wellbeing Creating and improving ecosystem connections CO2 sequestration Limiting rising temperatures; Reducing Urban Heat Island effect; Reducing water runoff Ecosystem-based adaptation (EbA);

Green Infrastructure (GI)
Green corridors Enhancing mobility and cycling; Improving city attractiveness and wellbeing Creating an ecological connection CO2 sequestration Stormwater retention and infiltration; Reducing the chance of combined sewer overflows Green Infrastructure (GI);

Natural Water Retention Measures (NWRM)
Peri-urban forest (Collserola) Providing green public places for leisure and sport activities; Air pollution control Creating and maintaining ecosystems CO2 sequestration Urban Heat mitigation Ecosystem-based adaptation (EbA);

Green Infrastructure (GI)
Hybrid dunes Enhancing the attractiveness of coastal zone Creating ecosystems   Adapting to sea level rise; Flood risk reduction Ecosystem-based adaptation (EbA);

Ecosystem-based Disaster Risk Reduction (ecoDRR)
Urban gardens Providing public green places and food supply; Improving city attractiveness and wellbeing; Restoring vacant and degraded areas; Air pollution control Ecosystem creation; Maintaining soil fertility; Pollination CO2 sequestration Local Climate Regulation Green Infrastructure (GI)

Impacts

The Trees Master Plan (2016) has defined different strategies for tree planting in Barcelona, implemented through 46 actions and a range of associated tasks that have been prioritised for the next few years. These would provide key services of climate regulation and pollution control (ClimateAdapt, 2016).

Several projects are being developed to increase ecosystem connectivity and landscape functions, such as the Urban Green Corridors Programme, connecting green areas in the city centre to other major green areas such as the Collserola Park (see figure 2 and figure 3). In this way, urban green spaces in Barcelona have increased considerably over the last 30 years.

Figure 2 The urban green corridors in Barcelona. Source: City of Barcelona.

For example, Barcelona City Council recently began transforming a major traffic node of the city into a large urban park (13 ha). The Canòpia urbana (urban canopy) project won an international design contest for Barcelona’s Glòries square, going beyond traditional park design by incorporating micro-climate regulation and biodiversity as key design aspects. The new park will feature a dense tree canopy cover in some areas in order to provide substantially cooler conditions inside the park, especially during summer time. The project aims to boost urban biodiversity by creating specific habitat conditions within the park, called ‘biodiversity pearls’ (source: OpenNESS project).

Figure 3 The Ciutadella-Collserola green corridor. Source: City of Barcelona.

Further away from the city centre, the peri-urban forest of Collserola natural park provides the city with direct and indirect 'ecosystem services'. The forest surrounds the city on the north-western side and, with a surface of 8 300 ha, accounts for about 3.5 million visitors per year (see figure 1). It is managed by the Consorci del Parc Natural de Collserola. A study (Depietri Y. et al., 2016) shows how Collserola Park enhances the liveability of the city of Barcelona itself. In particular, the forest strongly contributes to air pollution removal (+100 % compared with the green areas of the inner city alone). Collserola also contributes to urban cooling, notably through evapotranspiration. Colder air also flows at night into the city in the summer months easing high night temperatures.

Thanks to Collserola Park, Barcelona has very high cooling levels, compared with the European average. The same is true of Montjuïc Park, the largest urban park in Barcelona, and the second largest after Collserola Park. Montjuïc Park is located in the city centre and attracts millions of visitors per year.

Another key ecosystem is the coastal dunes, managed by the metropolitan administration. Here, the hybrid dunes project aims to construct and maintain semi-fixed dunes on heavily used urban beaches to optimise the flows of ecosystem services (Operas case study: Barcelona's hybrid dunes). In doing so, it helps preserve the beach system and protect against sea-level rise. This ecosystem-based adaptation to climate change also has a major positive economic impact on real estate and the tourism-related economy.

With the ‘Pla Buits’ (Empty-Spaces Plan), Barcelona City Council is currently trialling a new policy to promote the creation of urban green space and urban allotments in vacant areas based on civil society engagement.

Currently, two main types of urban allotments exist in Barcelona. The first type, the Xarxa d’Horts Urbans de Barcelona (Network of urban vegetable gardens of Barcelona), consists of vegetable gardens that are formally managed by Barcelona City Council. These vegetable gardens are usually divided into small plots of land that are individually managed by elderly gardeners. The second type consists of self-governed gardening initiatives where land is generally managed collectively.

Multiple Benefits

For example, other than providing and regulating ecosystem services (food supply, CO2 mitigation and urban heat island effect mitigation), urban gardens also offer citizens cultural ecosystem services. Urban gardens provide users with opportunities for restoring physical and cognitive connections with ecosystems, caring and nurturing life, as well as learning and education. Recreational purposes have historically been the main reason for urban policymakers and practitioners to promote urban gardening (Keshavarz N., 2016). These solutions enable Barcelona to become more sustainable and resilient and provide new opportunities for social inclusion.

Ecosystems covered

Urban, coastal, forest.

Key lessons

One particular lesson for Barcelona was enabling enough space for planting street trees. Most street trees have very limited space in the ground for their roots, with very little organic material and a compact soil with deficient nutrition. In most instances, this is because pavements are narrow and tree pits are small. Therefore, in public areas, streets wider than six metres should be designed in a way that provides scope for transforming individual tree pits into continuous pits (Source: ClimateAdapt, 2016).

Stakeholder participation

Barcelona City Council has established the More Sustainable Barcelona (B+S) network. This was created in 2002 with 800 members including schools, businesses, NGOs and universities who were invited to participate in a process that would lead to the drafting of a collective action plan and commitment: Barcelona's Commitment to Climate. This includes two ambitious mitigation and adaptation goals to be achieved by 2030: to reduce per capita CO2 equivalent emissions by 40 % in relation to 2005 levels and to increase the total urban green area by 1.6 km2.

Success and limiting factors

Maintaining joint work across different sectors, as well as high staff motivation are key to successful NbS projects. The creation of a biodiversity department in 2013 and the adoption of the Green Infrastructure and Biodiversity Plan certainly provided the basis for NbS implementation. Municipal governance combining the departments of urban planning, environment and housing, along with long-term commitment at all levels, contribute to the success of NbS initiatives.

While staff shortages can be a challenge, technical and organisational innovation is also a limiting factor as it needs to be understood and accepted by project-related stakeholders and society.

In this sense, training needs and social participation are key elements still to be tackled for a swifter implementation of NbS (Source: Barcelona City Council, 2016).

Financing

The estimated budget of the Trees Master Plan is €9.4 million a year. Of this budget, €8.3 million a year is available for tree management. The difference of €1.1 million/year is used for necessary related investments, mainly in the areas of improved soil and water management (ClimateAdapt, 2016).

Drivers for engagement

Barcelona was one of the case studies of the OpenNESS project, which aims to better integrate the ecosystem services approach into landscape and urban planning processes in the metropolitan region of Barcelona. The city was also part of the URBES project (2012-2014), a three-year research project funded by BiodivERsA that aimed to bridge the knowledge gap on the links between urbanisation, ecosystem services and biodiversity.

Barcelona City Council is a member of several sustainability-related city networks such as C40 and Eurocities. As a member of Local Governments for Sustainability (ICLEI), it was a pioneer participant of ICLEI’s Local Action for Biodiversity Programme.

Monitoring and evaluation

The Green Infrastructure and Biodiversity Plan contains a chapter entitled ‘Strategic lines and actions’, which suggests several programmes for implementation. The plan also contains a catalogue of actions (Green Surge, 2015) — however, proper long-term monitoring and evaluation has not been carried out yet.

Contacts:

Toni Pujol

Barcelona City Council — Urban Ecology — Division of Sustainability

E-mail: tpujol@bcn.cat

Margarita Parés

Barcelona City Council — Urban Ecology — Biodiversity Programme

E-mail: mparesr@bcn.cat

Sources and further information: