In the decade from 1998 to 2009 heat waves was the most prominent hazard in Europe causing more than 70 000 excess deaths during the extreme summer of 2003. In August 2003, for 9 consecutive days, the Paris metropolitan area experienced an extreme heat wave that caused 4867 estimated heat-related deaths. Exposure to climate change is relevant for identifying the potentially affected populations and the subsequent risk. Extreme temperature events are normal features of inter-annual temperature variability, but their frequency and intensity have increased both in Western and Central Europe as well as in Mediterranean regions. Deeper analysis of the 2003 heat wave, using longer time series, comes to the conclusion that it can be regarded as extremely unusual under the dominant European climate conditions of the twentieth century, while under conditions of climate change it might become more frequent. Heat waves have a major impact primarily on human health and socio-economics.

    Heat wave hazard varies within a metropolitan area due to specific characteristics such as topography, land cover/ land use, meteorological conditions and the presence of the Urban Heat Island phenomenon. On the other hand, population vulnerability to heat waves varies with age- primarily the elderly and also the infants being more vulnerable to high temperatures, and it is higher in urban areas due to higher population numbers and density. Health condition, poverty and isolation are also influential factors. From the above, it is expected that heat wave risk, being the combination of heat wave impact and probability of occurrence, is high in large cities. However, timely preventive measures can reduce the risk. A key problem is to prioritise the areas (districts/ boroughs) within the metropolitan area to target long-term planning.

    At the moment heat wave risk estimations rely on data (usually) from a single, centrally-located weather station in each city and they are broadly applied to entire urban areas or rely on short-term weather forecasts lacking however any explicit spatial dimension. Appraisal and quantification of spatially distributed heat wave risk currently and in the future are required to develop innovative tools and services for the subsequent design of targeted measures and strategies. Taking all the above into consideration, TREASURE- for the first time- integrates the expertise of epidemiologists, climatologists, Earth Observation scientists and IT developers into intelligent heat wave risk assessments for authorities and personalised tools for citizens all in accordance to Hyogo and UNISDR international initiatives. TREASURE will issue guidelines and disseminate its results via targeted actions. The approach will be applied and tested originally on two Mediterranean cities with different characteristics, and will set the grounds for application to any other European city together with the development of urban heat wave resilience strategies. Our vision is to make TREASURE a point of reference for Civil Protection mechanisms at European level.