It’s quite probable that cities will suffer greatly under the consequences of climate change. Especially coastal cities, however sustainable they may be, have to suffer the rising sea level as visualized by Climate Central. Amongst other ecological difficulties, generally increasing temperatures in conjunction with the urban heat island effect might heat up cities far beyond the envisaged maximum of the well-known ‘two-degree’ objective. According to a new scientific publication, the world’s cities can warm up by 8°C / 14.4F by 2100.
5 Degrees Extra in Cities by 2100 More Likely And Still Problematic
This would lead to even more health-impairing impacts for urban residents and a rising energy consumption for air conditioning in buildings. However, the forecast is based on the most unfavorable case that may occur. But no reason to take the issue far too lightly. The joint project of the Institute of Environmental Studies and the Universidad Nacional Autónoma de México makes clear that temperature increases of less than 8°C, in turn, are more likely due to the higher occurrence probability of the input data.
Cities By 2100 Are Well Advised to Shadow Heat Storages Like Concrete or Asphalt
Fortunately, there is a wide range of mitigation measures of which cities can take advantage. In order to lower urban heat, it is recommended to reduce the air temperature by applying the physical laws of the world we know. Planting lushly trees, for example, belongs to the most useful strategies. They provide shade, whereby pavements, buildings or asphalt roads cannot heat up that much and thus give off less heat to their surroundings in the evening and night. At the same time, the well-known natural cooling mechanism provided by evapotranspiration additionally cares for a lower air temperature. Fountains are a great option, too. The heat which is needed for evaporation is supplied by the air, the water and if necessary also by the environment.
The darker the surface, the more heat is absorbed and released during the night
Other options are white surfaces and fewer heat storages in the form of asphalt, concrete or pavement. Dark asphalt, for example, absorbs much more solar radiation than lighter concrete roads. The asphalt soaks up the energy during the day and keeps it like a heat storage. In the night, the asphalt releases the heat in form of long wave radiation into the urban environment and thus decelerates the cooling process during the night time. The darker the surface and the higher the heat capacity, the more heat is absorbed, stored and released later. In return, this causes higher energy usage associated with air conditioning. Furthermore, common air conditioning systems release additional heat via radiation and ventilation which is generated during the cooling process. A vicious cycle?