Ecosystem-based adaptation. Green and blue infrastructures Cities are not closed systems or self-contained. They are open systems, in constant interaction with their hinterlands. Surrounding ecosystems supply energy, food, and water, they also provide shelter and protection, which help adaptation to climate change and increase resilience of urban areas. Ecosystem-based adaptation (EbA) is increasingly recognized as an important player to prevent, protect from, resist to and mitigate natural hazards consequences (Xxxxxx et al., 2013). Concrete example: In tropical countries, restoring or conserving mangrove forest and coastal marshes has been shown to buffer storm surges and help protect coastal communities (Xxxxxx, 2008). One case study has shown that EbA could be more cost- effective than hard interventions. In the Maldives facing powerful tropical storms, building sea walls would cost about US$1.6-2.7 billion (Xxxxxx and Rönnbäck, 2003). In contrast, preservation of natural reefs, would have an initial set up cost of US$34 million and maintenance costs of US$47 million per year. Investment into natural infrastructure restoration and protection would maintain critical protection services and could generate up to US$10 billion per year in co-benefits (Xxxxxxx et al., 2009). In Europe, the Green and Blue Space Adaptation for Urban Areas and Eco Towns project (GRaBS) aims at integrating climate change adaptation into regional planning and development. XXxXX has compiled a database of 33 cases studies mostly from Europe and the US (Xxxxxxxxxxx and Xxxxxx, 2010) and several examples illustrate the breadth of interest of this approach (see also Chapter Error! Reference source not found.): The cooling influence of green spaces and roofs is used to reduce the urban heat island effect in many cities, for example: In Seattle, maintenance and restoration of vegetation is used to limit the hazards of landslides Conservation and restoration of wetlands as a buffer zone between the coast and the city of New Orleans Creation of sustainable urban drainage systems, including ditches, retention ponds, green roofs and green spaces in Malmö (see Xxxxxxxxxxx and Xxxxxx, 2010). There is now good evidence for the effectiveness of these "natural approaches" which have proved to provide flexible, cost effective and broadly applicable alternatives for reducing impacts of climate change (Xxxxxx et al., 2013). They also achieve multiple policy objectives by providing options for climate change mitigation, envi...
