So snow/ice cover underneath anthro aerosols increases warming? Have winter relative to summer temps increased because of this? - Greg ________________________________________ From: David Keith [david_ke...@harvard.edu] Sent: Friday, October 28, 2011 10:37 AM To: Rau, Greg; s.sal...@ed.ac.uk; geoengineering@googlegroups.com Subject: RE: [geo] White roof snag
Greg et al There are a number of reasons why white roofs might cause heating that are well explained in the paper. Among them local suppression of convection and the correlation between where the roofs are and absorbing dust particles. The roofs we plan to whiten tend to be in places with dirty air, and so the problem of absorption is much more pronounced than if we scattered the whitening randomly over the planet. Your analogy to large-scale albedo changes is false because both the interaction with convection and the correlation with dirty air are not present in that case. I think it will take more papers to really nail this down but there's nothing impossible about this result and at a glance the paper seems sensible and serious. Http://www.stanford.edu/group/efmh/jacobson/Articles/Others/HeatIsland+WhiteRfs0911.pdf David -----Original Message----- From: geoengineering@googlegroups.com [mailto:geoengineering@googlegroups.com] On Behalf Of Rau, Greg Sent: Friday, October 28, 2011 10:40 AM To: s.sal...@ed.ac.uk; geoengineering@googlegroups.com Subject: RE: [geo] White roof snag ""A worldwide conversion to white roofs," they found, could actually warm the Earth slightly due a complex domino effect. Although white surfaces are cooler, the increased sunlight they reflect back into the atmosphere by can increase absorption of light by dark pollutants such as black carbon, which increases heating. " So by analogy, increased snow/ice cover would "actually warm the Earth slightly" ? I don't think so, but please clue me in. - Greg ________________________________________ From: geoengineering@googlegroups.com [geoengineering@googlegroups.com] On Behalf Of Stephen Salter [s.sal...@ed.ac.uk] Sent: Friday, October 28, 2011 4:22 AM To: geoengineering@googlegroups.com Subject: [geo] White roof snag Hi All See http://www.guardian.co.uk/environment/2011/oct/27/white-roofs-global-warming and Jacobson, M., & Ten Hoeve, J. (2011). Effects of Urban Surfaces and White Roofs on Global and Regional Climate. Journal of Climate DOI: 10.1175/JCLI-D-11-00032.1<http://dx.doi.org/10.1175/JCLI-D-11-00032.1> Stephen Emeritus Professor of Engineering Design Institute for Energy Systems School of Engineering Mayfield Road University of Edinburgh EH9 3JL Scotland Tel +44 131 650 5704 Mobile 07795 203 195 www.see.ed.ac.uk/~shs<http://www.see.ed.ac.uk/~shs> -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to geoengineering@googlegroups.com. To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to geoengineering@googlegroups.com. To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
