Who is sensitive to these changes, at what time, and in which locations become central questions of spatial planning, with a view to fostering sustainable cities, good health, well-being, and decreased inequalities, in line with the United Nations’ Sustainable Development Goals. An integrated assessment of climatic and demographic indicators by TU Dortmund University (Technische Universität Dortmund), described in a companion article, reveals two major spatial patterns for Germany: urban growth in warmer climate types and high vacancy and the dismantling of settlements in drier climate types (Schulze Dieckhoff et al. 2018). In both cases, an extreme change in population volume and structure takes place in parallel with rising temperatures and the increasing presence of urban heat islands.  This leads to a need for specific, small-scale adaptation strategies to ensure resilience.
Spatial planning and adaptive capacity
Spatial planning has been identified as essential to climate change adaption (IPCC 2008; Stern 2007; European Commission 2009; Wilson et al. 2010; Schulze Dieckhoff et al. 2018), in particular because of its regulation of land uses. Using various strategies and a set of informal and formal tools, spatial planning may enhance the adaptive capacity of a city if it fosters collective learning and self-organization, encourages and motivates action in the face of uncertainty and complexity, mediates between rationality and intuition, and enables gradual and adaptive adjustment (Wiechmann 2008). The key challenges are: developing political and collective conviction; facilitating equitable processes and outcomes; and transforming planning systems from passive to proactive (Hurlimann et al. 2012, pp. 483–484). Alongside these challenges, spatial planners face scarce financial, human and land resources.
Here, we introduce two extreme cases in order to focus on the potential of contextual adaption strategies. Our cases take place in cities that have similar warming due to climate change, but different demographic circumstances: both have aging populations, but one city is growing while the other is shrinking.
The case of Sindelfingen
Sindelfingen is a medium-sized city in Baden-Württemberg, in southern Germany, with 64,000 residents. Located in the Speckgürtel (affluent commuter belt) of Stuttgart and home to the largest production plant of Mercedes-Benz worldwide, the city is characterized by continued population growth, mainly due to international migration. Current forecasts project additional growth of 4,000 inhabitants by 2030. Despite its heterogeneous population and ongoing in‑migration, Sindelfingen’s population is aging. These developments lead to growing demand for age-friendly design and mobility infrastructure (e.g. ramps instead of stairs, safer sidewalks, better access to public transport, and strategically placed benches).
Climate projections indicate a continuous warming of the temperature as well as more hot days and tropical nights in the near future. A dense building typology, along with persistent soil sealing  resulting from new development, induces higher surface temperatures and fosters urban heat islands within the inner city. The microclimatic effects of the Mercedes-Benz plant further exacerbate these conditions. As the most heat-exposed area (Figure 1), the downtown of Sindelfingen is also the most heat-sensitive area as a result of its dense building typology and an aging and growing population. Figure 2 shows specific locations in which population growth and/or concentrations of older adults make heat sensitivity a particularly critical issue. Especially in these areas, remaining fresh-air corridors and inner-city climatic compensation areas are of great ecological and social value to residents.
Source: based on ALKIS by the city of Sindelfingen and Esri, Digital Globe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA,USGS, AeroGRID, IGN and the GIS User Community.
Source: based on database by the city of Sindelfingen (December 31, 2015) and Esri, Digital Globe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN and the GIS User Community.
Conflicting demands—ecological, social, economic—lead to land scarcity. Potential densification areas are needed for microclimate compensation; areas for ecological offset are missing. The most recent residential development in Sindelfingen is located in an important fresh-air corridor. Commercial space is no longer available. The key questions regarding spatial planning in Sindelfingen are: How can we sustainably manage land scarcity? What indicators and thresholds should be used when deciding on the densification of urban areas? And what are the natural growth limits for a city that aspires to achieving the UN’s Sustainable Development Goals?
Sindelfingen traditionally supports green structures and energy efficiency. For example, a vision statement supporting a green Sindelfingen has been in force since the 1990s. A climate mitigation concept, addressing energy efficiency in public buildings, has been in effect since 2013 (Hertle et al. 2013). Formal planning tools also questions such as walkable cities, roof greening, and multifunctional land uses. Sindelfingen’s spatial planning activities are greatly supported by innovative data management (e.g. by compiling a Klimaatlas, or climate atlas), networking, and the transport planning system of the Verband Region Stuttgart (Greater Stuttgart Region).
However, linear planning strategies and tools have been criticized by leading experts in the spatial planning department, as demographic projections were mostly wrong in the past. In the face of these demographic and economic uncertainties, the planning department chose to focus on collective learning and inclusive coalitions through regular dialogue and cross-office workshops at various scales.
Regular cross-office workshops initiated by Sindelfingen’s planning department encourage collaboration on integrated assessments and strategies to deal with uncertainty, and form the basis for political and collective positions. In addition to internal expertise, external knowledge is integrated into the processes—for example, through participatory research projects and coalitions with universities. For example, the improved climate impact assessment that we undertook, and its implications for demographic and climatic interrelations in Sindelfingen (Figure 3) were broadly discussed in cross-office workshops. The final results of the research project are currently being prepared for political processes that embed climate-change adaptation into the political agenda. The planning department is aiming for parametric governance (e.g. a resolution on climate adaption that includes binding criteria for politicians), but also targeting economic and civic actors.
Source: based on Greiving et al. 2015, p. 315.
The economically driven interests of big economic players and individual landowners alike challenge climate-change adaptation in Sindelfingen. Owing to high investment costs, current construction projects still avoid adaptation measures such as roof greening, high-albedo surfaces, and blue infrastructure. The conflicting interests of different age and lifestyle groups also challenge adaptation strategies. Controversy persists, for example, over the question of parking lots versus trees. In addition to the collectively developed and binding criteria mentioned above, the proactive planning department in Sindelfingen relies upon consensus-building and transformation through participation and mobilization: periodic planning talks with big players such as Daimler AG to support and localize social corporate responsibility have been organized and landowners’ conflicting interests have been mediated by reflecting on who decides, why, and about what. While various actors discuss the interrelation of the economic, social, and ecological values underlying different adaptation measures, the implementation of commonly agreed-upon standards is anything but easy.
Therefore, the planning department also employs no-regret strategies (e.g. no heat-sensitive social infrastructure within the inner city and temporary/flexible/multifunctional land uses) as well as landmark projects. Innovative land use and design are able to combine various interests by remaining flexible, and are thus more likely to obtain political support.
The case of Halberstadt
Halberstadt is a medium-sized city in Saxony-Anhalt, in eastern Germany. It is characterized by ongoing population decline, mainly due to low birth rates and the out‑migration of young people. Recent forecasts project an additional population loss of 15% by 2030, to approximately 34,100 inhabitants. These demographic changes lead to a shrinking demand for social and technical infrastructure such as kindergarten classrooms and waste-disposal facilities. However, demand for age-friendly design and barrier-free mobility is growing due to the rapid aging of the population.
Climate projections indicate both an increase in dry days and an increase in heavy rainfall; given the rise in the temperature, scientists project more hot days and tropical nights. The dense building typology and large number of sealed parking lots, especially in the historic parts of the city, generate urban heat islands and floods downtown. As the most climatically exposed areas (Figure 4), the oldest parts of Halberstadt are also the most sensitive owing to both the dense building typology and the growing concentration of older adults (Figure 5). Facing the double urban challenge of climate change and demographic change, many German municipalities—supported by state programs—follow a combined strategy of upgrading the existing building stock and controlled settlement contraction in particularly affected or endangered areas. Accordingly, climate adaptation and demographic adaptation can potentially be linked by measures of managed retreat and urban restructuring. Conflicts are expected regarding the costs of the maintenance of underused infrastructure and a citywide barrier-free design that is more vulnerable (i.e. more likely to be affected by flash floods).
Source: based on ALKIS by the city of Halberstadt and Esri, Digital Globe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA,USGS, AeroGRID, IGN and the GIS User Community.
Source: based on database by the city of Halberstadt (December 31, 2016) and Esri, Digital Globe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN and the GIS User Community.
Informal planning instruments (e.g. urban development concepts, Vision Statement 2020, Sision Statement Social Halberstadt) are up to date and support the socio-ecological development of Halberstadt. The research project by TU Dortmund University further facilitated an information baseline on climate impacts. In joining the research project, the planning department aimed to mobilize political commitment by encouraging a public debate on proactive climate adaptation based on hard facts, and linked the results with the tacit knowledge of local experts in cross-agency workshops. This has already led to a growing consciousness of challenges regarding the uncertainty of demographic and climatic developments and of the importance of integrated adaptive strategies. For example, recent public tenders (e.g. for the new mobility concept) asked that climate changes and impacts be taken into consideration. Owing to a lack of financial and human resources, the planning department focuses on co-production in climate-change adaption processes: (a) participatory mapping, city walks and Reallabore (living labs) to consider emotions, intuitions and tacit knowledge in impact assessments and spatial developments; (b) co-production of climate-change adaptation measures (e.g. the potential future maintenance of the city’s green infrastructure through private sponsorship). To support these processes, the planning department is currently preparing a concept for applying redevelopment funds by adding climate impacts as an urban deficiency. By bringing current knowledge on local climate change and demographic change and resulting conflicts in Halberstadt to the surface, city planners aim to facilitate compromise solutions addressing ongoing urban dynamics.
Spatial capacity planning for resilient cities
Spatial planning strategies and tools in Sindelfingen and Halberstadt show great potential for enhancing the adaptive capacity and, therefore, the resilience of those cities. In the face of demographic and economic growth, spatial planners in Sindelfingen are more likely to rely on strategic navigation along a set of collectively developed goals and to mediate conflicting interests and values, especially addressing global players. In contrast, planners in Halberstadt pursue a dual strategy. On the one hand, they build upon strategies and concepts that have been prepared by external experts with the aim of mobilizing political commitment. On the other hand, they encourage self-organization and self-government to trigger local stakeholder-driven transformation processes in the face of demographic and economic decline. Adaptive capacity is determined by local governance and structural potential, as different strategies and tools are being used. Both cities are still at the very beginning of climate-change adaptation; however, they demonstrate two possible ways of adaptive capacity building through spatial planning: consensus-based in Sindelfingen, and conflict resolution–based in Halberstadt.
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