Social vulnerability assessment of the Cologne urban area (Germany) to heat waves: links to ecosystem services.

More than three-quarters of the European population live in urban areas and this proportion is increasing, leading, in some cases, to increased vulnerability of cities to environmental hazards. The health impacts of heat waves are aggravated in cities due to the high density of buildings, the fragmentation of green areas and the higher concentrations of air pollutants. Ecosystems can provide important benefits that mitigate the impacts of heat waves but at the same time can themselves be affected by the hazard, thus limiting their services. The objective of this study was to assess the vulnerability of the Cologne urban population to heat waves, taking into consideration a range of social and ecological variables. Based on the MOVE framework, indicators were developed and GIS applications were used to spatially assess the relative vulnerability of the 85 districts of Cologne to heat waves. The insights gained were integrated and corroborated with the outcomes of stakeholders' interviews. As environmental factors play a major role in this assessment, it is suggested that ecosystem management in Cologne and its surroundings be improved. In addition, though vulnerability is higher in central districts, attention needs to be paid to the periphery where the most susceptible groups reside.