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Essay / Demographic transition from rural to urban areas
From 2000 to 2030, urbanized areas will almost triple1 due to the demographic transition from rural to urban areas. The use of dark building materials, such as asphalt and concrete, leads to a lower albedo in urbanized areas than in the natural environment2, thereby promoting local and global warming. In turn, increasing urban albedo could support climate stabilization efforts3. Here we study the potential effect of increasing albedo in a representative set of European cities relying on instantaneous radiative forcing (IRF), urban cooling and the resulting effect on mortality, ozone formation and energy consumption. Beyond any geographic distinction, the cities show that increased albedo in compact cities has cooling potential and can provide better living conditions, motivating local governments. Furthermore, large cities could have greater potential through IRF, thereby contributing to the global common good. Overall, stratified and multilevel policies could be applied to mitigate the global and local climate depending on the level of potential benefits and co-benefits that arise. The contribution of cities to global climate change mitigation and energy consumption is receiving increasing attention4. As progress in tackling climate change remains stuck in complex negotiations5 at the international level, cities could provide the appropriate spatial scale to address multi-faceted challenges such as climate change6. City decision-makers successfully implement local climate change mitigation measures to achieve co-benefits and savings6, but respond reluctantly to top-down mitigation and adaptation plans7. However, as climate change mitigation efforts remain local, no single city will leave measurable benefits...... middle of paper ......nts. Ground. Energy doi:10.1016/j.solener.2012.07.00323. Kalkstein, LS & Valimont, KM An assessment of summer discomfort in the United States using a relative climatological index. Bull. Am. Meteorol. Soc. 67, 842-848 (1986).24. Baccini, M. et al. Effects of heat on mortality in 15 European cities. Epidemiol. Camb. Mass 19, 711-719 (2008).25. Sailor, DJ & Dietsch, N. The Urban Heat Island Mitigation Impact Screening Tool (MIST). Approximately. Model. Software. 22, 1529-1541 (2007).26. Susca, T. Improving life cycle assessment (LCA) methodology to include the effect of surface albedo on climate change: comparing black and white roofs. Approximately. Pollute. 163, 48-54 (2012).27. Joos, F. et al. Feedbacks of global warming on terrestrial carbon uptake under the Intergovernmental Panel on Climate Change (IPCC) emission scenarios. Global. Biogeochemistry. Cycles 15, 891–907 (2001).