By using a scale framework, we examine how cross-scale interactions influence the implementation of climate adaptation and mitigation actions in different urban sectors. Based on stakeholder interviews and content analysis of strategies and projects relevant to climate adaptation and mitigation in the cities of Copenhagen and Helsinki, we present empirical examples of synergies, conflicts and trade-offs between adaptation and mitigation that are driven by the cross-scale interactions. These examples show that jurisdictional and institutional scales shape the implementation of adaptation and mitigation strategies, projects and tasks at the management scale, creating benefits of integrated solutions, but also challenges. Investigating the linkages between adaptation and mitigation through a scale framework provides new knowledge for urban climate change planning and decision-making. The results increase the understanding of why adaptation and mitigation are sometimes handled as two separate policy areas and also why attempts to integrate the two policies may fail.

Recently, considerable focus, e.g., in the fifth IPCC (Intergovernmental Panel on Climate Change) Assessment Report (2014) has been trained on why adaptation and mitigation have not been developed more than at present, with relatively few local government actions taken compared with, for example, more discursive policy agreement on the importance of the issue of climate change. Going beyond a focus on general limits and barriers, this comment suggests that one important issue is that climate change has not yet been sufficiently integrated into the state regulative structure of legislation and policy-making. A comparison between three cases suggests that local developments that are not supported in particular by binding regulation are unlikely to achieve the same general level of implementation as issues for which such regulative demands (and thereby also requirements for prioritization) exist. This constitutes an important consideration for the development of adaptation and mitigation as policy areas, including on the local level.

The local level and private actors play an important role in the implementation of climate change adaptation. The engagement of the private sector and citizens has received increasing attention in recent years. Local authorities' choice of policy instruments, the distribution of responsibilities and the benefits of adaptation as a public or a private good have a bearing on the involvement of private actors. Based on interviews and documents from Copenhagen and Helsinki, we analyse how public authorities' choices, to whom and how they shift responsibilities, can foster transformational, participatory or market-oriented elements of adaptation. The results indicate that local authorities play a dominant role in providing adaptation. Public authorities steer where the private sector and citizens are expected to take responsibilities. This mix of top-down steering, market mechanisms and citizen involvement might reduce the advantages that a shift of responsibilities towards private actors could provide for the handling of climate change adaptation.