The urban heat island effect in Malta and the adequacy of green roofs in its mitigation

Abstract

Urbanisation is a reality of every major western society. The growth of cities, however, often results in major environmental impacts that not only effect the natural world but also humanity as well. One of these impacts is the Urban Heat Island (UHI) a phenomenon that influences the temperature inside built-up areas, often resulting in uncomfortably hot air temperature, especially in summer. However, as global climate change predictions keep forecasting warmer periods for regions such as Malta, UHI has the potential to transform from a nuisance to a deadly reality more often than in the present. This work strives to get an understanding of the poorly studied UHI phenomenon in the Maltese Islands and through foreign literature, look into the potential of green roofs in its mitigation locally. Data collection via a modified vehicular transect has shown that UHI is a reality even in Malta, a small island with a strong marine influence. Even though UHIs are not continuous because of the highly heterogeneous urban-rural areas of Malta, all urban sites investigated show a higher temperature than the surrounding countryside. The highest UHI intensity was of around 1.5⁰C. The presence of vegetation has indicated lower temperatures, even when present in urban gardens. For this reason, this study shows that in Malta green roofs would aid the mitigation of UHIs as a part of an UHI mitigation plan.