Urban expansion takes massive proportions in recent years. In Europe, almost 73 % of the population lives in cities and this is foreseen to overcome 80 % by 2050. The combined effect of global climate change and rapid urbanization is expected to make the residents of urban areas more vulnerable to a range of urban environmental problems, strongly connected with the Urban Heat Island (UHI) effect, a phenomenon that is considered to be one of the most representative and well-documented manifestations of climate modifications due to urbanization.
Urbanization induces significant atmospheric and surface alterations, leading to a modified thermal climate that is warmer than the surrounding non-urbanized areas. UHI has substantial impacts on human health, regional economies and environments. Concerning people’s health, the epidemiological literature has well documented the strong effects of heat within urban areas, especially within densely inhabited deprived areas and where vulnerable subjects (e.g., elderly) live.
Other adverse impacts and urban environmental problems associated with UHI effect include energy consumption, deterioration of air quality and stressful bioclimatic conditions. UHI effects become even more significant as the duration of Heat Waves (HWs) is expected to increase due to climate change. Several research results show that UHIs interact synergistically with HW episodes exacerbating their effects on urban residents. Especially over Europe, the Mediterranean region is projected among the areas most at risk regarding health impacts, in particular in densely populated urban centers. For this, LIFE ASTI project targets the UHI effect and its effects, primarily on human mortality by developing, piloting and validating a set of modeling systems for short-term prediction, as well as for future projection, of the UHI effect in two Mediterranean cities, namely Thessaloniki and Rome.
The two Mediterranean metropolitan areas were chosen to give a representative geographical coverage of the problem, reflecting different environmental conditions, demographic data and socioeconomic factors. In particular, Thessaloniki’s heat island is more pronounced during the summer with the nocturnal UHI intensity being the strongest, while the city’s coastal environment has a significant impact on UHI, as Thessaloniki is exposed to sea breezes frequently. In Rome, UHI is evident in the densely built up areas, i.e. center and east sides, especially during summer when its intensity reaches maximum.