This report provides a concise and forward-looking summary of how a transformative transition towards a more sustainable blue economy could take place in Sweden, and thereby also contribute to a more sustainable development outside Sweden. The report constitutes a basis for analysis of obstacles to and incentives for the opportunities of a sustainable blue economy, and a roadmap for the implementation of Sweden’s Maritime Strategy.

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<p>Globally climate change has increased exposure to multiple hazards. In Sweden, 10-year events of precipitation and streamflow have started to cluster around the summer months for most of the country. However, Sweden's south and west coasts are especially vulnerable to river flooding events caused by extreme sea surges during the winter. This national-level analysis needs to be combined with detailed local assessments to quantify the hazard properly, its potential impacts and cascading effects. In response to this need, we explore the impacts of multiple hydrometeorological (i.e., weather and water) events that happen simultaneously or close together in Halmstad. Furthermore, we investigate the effects of climate change on the intensity and frequency of these hazards by focusing on extreme – low likelihood but high impact – events. Due to its geographical location, Halmstad is particularly vulnerable to flooding risks. Wind and waves combine to make the city vulnerable to flooding and storm surges. That confluence triggers extreme local sea level rise, resulting in high sea levels in Halmstad compared to nearby coastal towns. These compound flooding events in Halmstad are expected to increase in future climate scenarios. We will simulate multiple scenarios of compound flooding events with a two-dimensional hydrodynamic model. The model's values used as boundary conditions will be based on computed joint return intervals for fluvial flooding and extreme sea surge. This study can not only be used to support local adaptation strategies but will also contribute to the body of knowledge on the issue of compound flooding events in a changing climate. Local-scale assessments like this one are necessary for a nuanced understanding of the possible impacts of multiple hazards on society. At the same time, societies' dependency on critical infrastructure and vital societal services is increasing due to growing system complexity and interconnectedness. Together, these shifts will likely increase societal vulnerability and impact adaptive capacity.</p>

The HydroHazards project explores locations, sectors, and vital societal functions exposed to multiple hydrometeorological events. The project devises methods and tools to assess the cascading effects that multiple events may have upon critical infrastructures and social groups. This brief provides an overview of these methods and tools and a summary of their application in a Swedish case study (see Figure 1 for a timeline of activities).

Floods disproportionately affect disadvantaged groups. Social vulnerability assessments are the first step in designing just and equitable flood risk reduction strategies. In Sweden, earlier social vulnerability indices apply top-down approaches. In this paper, we develop and apply a combined bottom-up and top-down approach to assess social vulnerability to flooding at a sub-municipal level in Sweden. We tested an indicator-based climate risk and vulnerability framework, more specifically the impact chain method suggested by the Vulnerability Sourcebook. We involved stakeholders using various participatory methods in three workshops, interviews, and informal exchanges to identify variables and indicators for social vulnerability. The Indicators were aggregated into a composite social vulnerability index using exploratory factor analysis. We thereafter mapped the social vulnerability index scores to uncover spatial injustices. We found that the proposed social vulnerability index captures municipal nuances better than national-level approaches. Our findings indicate an uneven spatial distribution of social vulnerability that mimics the overall patterns of income segregation found in the municipality. Many areas that score low in social vulnerability endure high exposure to floods. The social vulnerability index can support municipalities in designing just and equitable interventions toward flood risk reduction by serving as an input to policymaking, investment strategies, and civil protection.