Decreasing Albedo in European Cities

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Earth is currently in transition from a mostly rural to a mostly urban planet. In 2030 the urbanized areas will be nearly tripled compared to 2000 (Seto et al. 2012). The use of dark building materials, such as asphalt and concrete, leads to a lower albedo in urbanized areas than in natural environment. Lower albedo increases ambient and global temperature. Inversely, the substitution of rooftops’ membranes and pavements’ traditional materials with bright ones and a wise planning of future urban development can increase albedo and support climate stabilization efforts. Here we investigate the potential effect of the increase in albedo on the instantaneous change in radiative forcing in a representative set of European cities. We find a distinct but surprising geographical variation of the potential. Southern European cities have highest albedo mitigation potential; but Scandinavian cities demonstrate equal potential to northern-central European cities. While the realistic global mitigation effects remain negligible, local reduction in heat stress justifies policy interventions. The IPCC Working Group I Fourth Assessment Report informs that since pre-industrial times up 2005, the increase in Earth’s albedo by Land Use and Land Cover Change (LULCC) led to a decrease in radiative forcing (RF) of 0.2 [± 0.2] W m-2 (Salomon et al. 2007). The magnitude of the LULCC-induced decrease in RF is considerable. It is comparable to the effect of some anthropogenic long-lived greenhouse gases in the atmosphere (e.g., nitrous oxide). The effect of the LULCC on RF is mainly ascribable to the increase in Earth’s albedo due to deforestation and modification of land for agricultural use (Foster et al. 2007). However, it includes the effect of urbaniz... ... middle of paper ... ...a global climate model. Geophysical research letters, 37, L03701, doi:10.1029/2009GL042194 (2010) 20. PIK, 2013. The Climate Impacts: Global and Regional Adaptation Support Platform. ci: grasp 2.0. Retrieved on November 2013 from: 21. Fischer, E.M., Schär, C. Consistent geographical patterns of changes in high-impact European heatwaves. Nature Geoscience 3, 398 – 404 (2010) 22. IPCC. Climate Change 2007. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA (2007) 23. Joos, F., Prentice, I.C., Sitch, S., Meyer, R.H., Platter, G., Gerber. S. & Hasselmann. K., Global warming feedbacks on terrestrial carbon uptake under the Intergovernmental Panel on Climate Change (IPCC) emission scenarios. Global biogeochemical cycles, No. 15 (4) 891 – 907 (2001)
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