Authors: Yaella Depietri, Torsten Welle, Fabrice G. Renaud

More than three quarters of the European population lives in urban areas and this proportion is increasing, leading in some cases to increased vulnerability of cities to hazards. The health impacts of heat waves are aggravated in cities due to the higher concentration 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 affected the by hazard, thus limiting their services. The objective of our study is to assess the vulnerability of the Cologne urban population to heat waves, taking into consideration a range of social as ecological variables. Based on the framework developed during the MOVE (Methods for the Improvement of Vulnerability Assessment in Europe) EU funded project, indicators were designed and GIS applications were used to spatially assess the relative vulnerability of the 85 districts of Cologne to heat waves. The insights gained were then integrated and corroborated with the outcomes of ad-hoc stakeholders interviews. As environmental factors play a major role in this assessment, it is suggested to improve ecosystem management in Cologne. In addition, though vulnerability is higher in central districts, attention needs to be paid to the periphery where the most vulnerable groups reside.