From 2000 until 2030 the urbanized areas will be nearly tripled1 because of the demographic transition from rural to urban. The use of dark building materials, such as asphalt and concrete, leads to a lower albedo in urbanized areas than in natural environment2, fostering local and global warming. In turn, the increase in urban albedo might support climate stabilization efforts3. Here, we investigate the potential effect of the increase in albedo in a representative set of European cities relying on instantaneous radiative forcing (IRF), urban cooling and the consequent effect on mortality, ozone formation and energy use. Apart from any geographical distinction, cities show that the increases in albedo in compact cities have a cooling potential and may provide better living conditions being motivating for local governments. Besides, wide cities may have a better potential on IRF contributing to purse global common good. Altogether, stratified and multilevel policies might be applied to mitigate global and local climate according to the level of the potential deriving benefits and co-benefits.
The contribution of cities to global climate change mitigation and energy use gains increasing attention4. As progress in addressing climate change remains stuck in complicated negotiations5 on an international level, cities might be the appropriate spatial scale to address multi-faceted challenges such as climate change6. Cities’ decision-makers successfully implement local climate-change mitigation measures to pursue co-benefits and cost-savings6 but reluctantly react to top-down imposed mitigation and adaptation plans7. However, as the efforts of climate change mitigation remain local, any single city will hardly leave measurable benefits on global scale, showing the importance of a collaborative approach.
Since pre-industrial times up 2011 land use and land cover change, mainly ascribable to deforestation and modification of land for agricultural use8, decreased radiative forcing (RF) by 0.15 [± 0.1] W m-2 9. Cities – because of the lower albedo compared to the natural environment – counteract the increase in Earth’s albedo contributing to urban-induced warming both on a local and global scale2,10 (e.g., heat waves and urban heat island (UHI)). The increasing regional and local temperatures may affect human health and energy use influencing, in turn, climate change. Because of the rapid ongoing urbanization1, urban albedo may progressively become an important driver for climate change.
Here, we focus on albedo increase, as a low-to-zero cost option on municipal level for counteracting urban-induced warming (e.g.,11,12). Since most of rooftops and road areas are located in Europe and in northern America13, we evaluate the effect of albedo modifications in a comprehensive sample of European cities to deliver information for the delineation of local and regional science-based climate-mitigation and adaptation policies. Relying on previously established...