Environmental Framework for Mitigating High Temperatures in Global Cities Exploiting Urban Greening: Two Case Studies: Cairo, Egypt, and Rome, Italy

Urban heat islands (UHIs) and extreme high temperatures (EHT) are manifested in cities globally and caused severe impacts and multiple risks to citizens. This chapter presents an environmental framework for mitigating high temperatures through urban green coverage (UGC) application in two global large cities: Cairo city, Egypt; and Rome, Italy. The study aims at prioritizing urban areas for UGC implementation by correlating land surface temperatures (LST) with socio-economic data of the vulnerable groups in the selected case studies (Cairo and Rome) to determine high risk areas that need intervention. Results show that in Cairo city, the highest risk was depicted in five districts (Al-Basatin, Tura, AlMokattam, Helwan, and Madinat Naṣr-1), while in Rome, the highest risk was observed in three municipalities: municipality V (Prenestino/Centocelle), municipality VI (Roma Delle Torri), and municipality VII (Appio-Latino/Tuscolano/Cinecittà). A simulation was conducted using ENVI-met program to examine the effect of climate change (CC) on the selected areas by comparing air temperatures in the baseline case in Cairo city with the expected scenarios in 2050 and 2080. The CC weather scenarios for 2050 and 2080 were generated using CCWorldWeatherGen based on the IPCC Third Assessment Report. Moreover, the cooling benefit of the proposed UGC (trees, vertical greening, and green roofs) was tested to assess its role on the urban micro-climate in offsetting 2080 CC impacts in Cairo, Egypt. In addition, a comparative analysis was conducted between the two case studies (Cairo and Rome) to determine the effect of using street trees in mitigating EHT in 2022. Finally, the chapter highlights the recommendations for UGC applications to mitigate UHIE in large cities.