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Is heat becoming a major threat to cities? Following the heat wave in Europe in 2003, which is estimated to have caused the deaths of 70,000 people, municipal authorities began to develop adaptation and mitigation plans and programs. Legal obligations to consider climate change within various development projects have been defined, e.g. by the latest amendment of the EU EIA (Environmental Impact Assessment) Directive (2014/52/EU) and the Federal Building Code (BauGB §1a (5)). However, urban heat hazards have not yet received as much attention as, for example, carbon dioxide emissions as drivers of global warming. Dense urban structures, high buildings, dark surfaces, and high population densities trigger urban heat effects. With about 3/4 of Europeans living in cities, measures to reduce heat-related impacts are needed. This paper evaluates how German cities have implemented measures towards climate change adaptation. The results show that 24 out of 30 cities have developed mitigation and/or adaptation plans, with a majority focusing on mitigating CO₂, indicating less awareness of urban heat hazards. Moreover, we found elaborate and comprehensive examples which might serve as blue-prints for adaptation strategies. Based on the inhomogeneous scope of the different plans and programs, there remains a need for guidance and more knowledge exchange among the cities on mitigation/adaptation options and preferably information on their effectiveness, to further assist cities in tackling heat stress.

Urban and environmental planning plays an important role in climate change adaptation. In this area, most German cities have developed adaptation strategies, inter alia tackling growing urban heat effects. Still in question, however, is how these measures will be implemented at the local level. The goal of this paper is to assess the implementation probability of climate change adaptation measures via local land-use plans using a Bayesian Network approach. Six plans were analysed in-depth. We used expert interviews to estimate the likelihood of implementing climate-adapted measures. Whether a local land-use plan stimulates climate change adaptation depends on a combination of different factors, e.g. the setting of the borough councillor in exchange with an investor, in a next step the willingness of the plans’ creator to implement adaptation strategies as well as an existing environmental report.

Extreme heat is a growing concern for cities, with both climate change and the urban heat island (UHI) effect increasingly impacting public health, economies, urban infrastructure, and urban ecology. To better understand the current state of planning for extreme heat, we conducted a systematic literature review. We found that most of the research focuses on UHI mapping and modeling, while few studies delve into extreme heat planning and governance processes. An in-depth review of this literature reveals common institutional, policy, and informational barriers and strategies for overcoming them. Identified challenges include siloed heat governance and research that limit cross-governmental and interdisciplinary collaboration; complex, context-specific, and diverse heat resilience strategies; the need to combine extreme heat “risk management” strategies (focused on preparing and responding to extreme heat events) and “design of the built environment” strategies (spatial planning and design interventions that intentionally reduce urban temperatures); and the need for extensive, multidisciplinary data and tools that are often not readily available. These challenges point to several avenues for future heat planning research. Ultimately, we argue that planners have an important role to play in building heat resilience and conclude by identifying areas where scholars and practitioners can work together to advance our understanding of extreme heat planning.

The stratification of upper layer of coastal water can be regarded as an unused energy source in summer. In addition, the coastal water has capability to store the urban heat owing to the heat capacity difference to the atmosphere. This study assesses the usage and capacity of coastal water for heat storage. A set of numerical simulations of the urban heat release into coastal zone is performed for Osaka bay of Japan. The estimated urban heat along Osaka Bay is 1 kGJ/h within the distance from 500 m to 5000 m from the coastal line. The urban heat released within 2000 m from the coastal line had little influence on sea surface temperature of Osaka Bay.