Stephen (or John, or Phil, or anyone else) have any of your modellings of cloud brightening looked at this effect? If you were to brighten clouds under a dark aerosol (eg Asian Brown Cloud or equivalent off west africa) might you not be trading warming at the surface for warming at the dark aerosol layer above the cloud, and thus a) getting less of an effect in terms of overall cooling and b) contributing to an increased stability in the amtopsheric column that would suppress convection (thus perhaps having an effect on the clouds themselves?) Doesn't seem obvious how this would net out -- if warming the atmosphere above made the clouds more stable i suppose this might increase the cooling for a given seeding. Is it something you've looked at?
On Oct 28, 5:37 pm, David Keith <david_ke...@harvard.edu> wrote: > 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+White... > > 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-... > > 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 > 195www.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 > athttp://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.
