The long-term effect of increasing the albedo of urban areas

Solar reflective urban surfaces (white rooftops and light-colored pavements) can increase the albedo of an urban area by about 0.1. Increasing the albedo of urban and human settlement areas can in turn decrease atmospheric temperature and could potentially offset some of the anticipated temperature increase caused by global warming. We have simulated the long-term (decadal to centennial) effect of increasing urban surface albedos using a spatially explicit global climate model of intermediate complexity. We first carried out two sets of simulations in which we increased the albedo of all land areas between 20 and 45 latitude respectively. The results of these simulations indicate a long-term global cooling effect of 3 10 15 K for each 1 m 2 of a surface with an albedo increase of 0.01. This temperature reduction corresponds to an equivalent CO2 emission reduction of about 7 kg, based on recent estimates of the amount of global warming per unit CO2 emission. In a series of additional simulations, we increased the albedo of urban locations only, on the basis of two independent estimates of the spatial extent of urban areas. In these simulations, global cooling ranged from 0.01 to 0.07 K, which corresponds to a CO2 equivalent emission reduction of 25‐150 billion tonnes of CO2.

[1]  Melvin Pomerantz,et al.  Cooler Paving Materials for Heat-Island Mitigation , 1998 .

[2]  Alexei G. Sankovski,et al.  Special report on emissions scenarios , 2000 .

[3]  Limin Yang,et al.  Development of a global land cover characteristics database and IGBP DISCover from 1 km AVHRR data , 2000 .

[4]  Stephen Sitch,et al.  Global warming feedbacks on terrestrial carbon uptake under the Intergovernmental Panel on Climate Change (IPCC) Emission Scenarios , 2001 .

[5]  H. Akbari,et al.  Cool surfaces and shade trees to reduce energy use and improve air quality in urban areas , 2001 .

[6]  Marika M. Holland,et al.  The UVic earth system climate model: Model description, climatology, and applications to past, present and future climates , 2001, Data, Models and Analysis.

[7]  Ronnen Levinson,et al.  Inclusion of cool roofs in nonresidential Title 24 prescriptive requirements - eScholarship , 2002 .

[8]  Katrin J. Meissner,et al.  The role of land surface dynamics in glacial inception: a study with the UVic Earth System Model , 2003 .

[9]  Gunnar Myhre,et al.  Uncertainties in radiative forcing due to surface albedo changes caused by land-use changes , 2003 .

[10]  M. Winton.  Surface Albedo Feedback Estimates for the AR4 Climate Models , 2006 .

[11]  Ken Caldeira,et al.  Transient climate–carbon simulations of planetary geoengineering , 2007, Proceedings of the National Academy of Sciences.

[12]  R. Betts,et al.  Changes in Atmospheric Constituents and in Radiative Forcing. Chapter 2 , 2007 .

[13]  Robert M. Hamwey.  Active Amplification of the Terrestrial Albedo to Mitigate Climate Change: An Exploratory Study , 2007 .

[14]  Ken Caldeira,et al.  Stabilizing climate requires near‐zero emissions , 2008 .

[15]  Ronnen Levinson,et al.  Evolution of Cool-Roof Standards in the US , 2008 .

[16]  H. Akbari,et al.  Evolution of cool-roof standards in the United States , 2008 .

[17]  Andreas Oschlies,et al.  Future changes in climate, ocean circulation, ecosystems, and biogeochemical cycling simulated for a business‐as‐usual CO2 emission scenario until year 4000 AD , 2008 .

[18]  Hashem Akbari,et al.  Urban Surfaces and Heat Island Mitigation Potentials , 2008 .

[19]  Alicia Palacios-Orueta,et al.  Surface temperature cooling trends and negative radiative forcing due to land use change toward greenhouse farming in southeastern Spain , 2008 .

[20]  M. Friedl,et al.  A new map of global urban extent from MODIS satellite data , 2009 .

[21]  J. Shepherd,et al.  Geoengineering the Climate: Science, Governance and Uncertainty , 2009 .

[22]  T. Lenton,et al.  The radiative forcing potential of different climate geoengineering options , 2009 .

[23]  A. Rosenfeld,et al.  Global cooling: increasing world-wide urban albedos to offset CO2 , 2009 .

[24]  Sensitivity of ocean acidification to geoengineered climate stabilization , 2009 .

[25]  H. Damon Matthews,et al.  The proportionality of global warming to cumulative carbon emissions , 2009, Nature.

[26]  Alvaro Montenegro,et al.  Lifetime of Anthropogenic Climate Change: Millennial Time Scales of Potential CO2 and Surface Temperature Perturbations , 2009 .

[27]  K. Oleson,et al.  Effects of white roofs on urban temperature in a global climate model , 2010 .

[28]  Hashem Akbari,et al.  Global Cooling: Policies to Cool the World and Offset Global Warming fromCO2 Using Reflective Roofs and Pavements , 2010 .

[29]  H. Akbari,et al.  Radiative forcing and temperature response to changes in urban albedos and associated CO2 offsets , 2010 .

[30]  Amadeo R. Fernández-Alba,et al.  Including CO2-emission equivalence of changes in land surface albedo in life cycle assessment. Methodology and case study on greenhouse agriculture , 2010 .

[31]  Thomas Raddatz,et al.  Biogeophysical versus biogeochemical climate response to historical anthropogenic land cover change , 2010 .

[32]  Global and Local Effect of Increasing Land Surface Albedo as a Geo-Engineering Adaptation/Mitigation Option: A Study Case of Mediterranean Greenhouse Farming , 2011 .

[33]  J. Kok,et al.  The physics of wind-blown sand and dust , 2012, Reports on progress in physics. Physical Society.

[34]  M. Jacobson,et al.  Effects of Urban Surfaces and White Roofs on Global and Regional Climate , 2012 .

[35]  H. Akbari,et al.  Global cooling updates: Reflective roofs and pavements , 2012 .

[36]  S. Solomon,et al.  Cumulative carbon as a policy framework for achieving climate stabilization , 2012, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.