Planning and assessment methods for climate regulating services Ecosystem services to improve natural cooling in metropolitan areas

The paper proposed deals with the role of Ecosystem Services (ES) in urban areas for Climate Change (CC) adaptation. Ecosystems, both natural and managed, could exert a strong influence on urban microclimate and air quality and future management of ecosystems has the potential to modify concentrations of a significant number of Greenhouse gases (GHG). In detail, the paper focuses on phenomena related to the rising of high temperatures in urban areas during summer heat waves (Urban Heat Island - UHI). Urban Heat Island -UHI- is a thermal anomaly affecting large urban areas that show temperatures which are higher than surrounding rural areas. The intensity of this phenomenon can be quantified as the maximum difference between the average temperature of urban air and that of the surrounding rural environment. Compared to the latter, the temperature increase is more pronounced at night than by day; in daylight the temperature difference between urban and suburban areas can range from +1 ° C to +3 ° C, while at night it can reach values ranging from +7 to +12 ° C (Goward, 2009). This phenomenon occurs especially in big cities where there is a widespread overbuilding, the prevalence of paved surfaces on green areas, the use of building materials with low ability to dissipate heat. To these causes other factors are added due to the location of the urban area (local morphology, microclimate features, presence of huge water bodies) and to human activities (emissions from motor vehicles, industrial plants, heating and air conditioning systems for household use). Although the benefits of ES, like green spaces and water basins, in reducing high temperatures are renowned, few efforts have been done to investigate how ES threshold dimensions and optimal morphology within urban areas could maximize these advantages and minimize GHG emissions and energy consumptions. The research introduces a methodology to analyze the links between regulation ES provision (green areas, water basins) and high temperatures phenomenon in a densely built metropolitan area. This methodology has been applied to the metropolitan area of Naples (Italy), one of the largest and most populated in Italy. By processing remote sensing infrared summertime thermography, NDVI map and land use map in a GIS environment, it has been possible to carry out a correlation analysis among urban temperatures, urban planning parameters, green spaces and water. Interesting results have been achieved concerning how green spaces and water could be used in urban planning practices to contrast the increase in temperature, promoting the natural cooling of urban environment. Strong connections between surface extension parameters, typology (of green or water), frequency in the urban context, distance from the core of ES area and urban temperature reduction have been found. Interesting results from the urban planning point of view concern the spatial incidence that ES have on surrounding areas and therefore which should be the best shapes, allocations and density of green and water. Results regard the set up of urban design parameters to reduce the increase in urban temperature with the related threshold dimensions and morphology features. The results obtained are generally applicable in different contexts.