Hello All, I think this is an interesting and seemingly authoritative observational study, with some so far limited modelling support.It will be valuable to ascertain whether the findings - at the moment limited to low clouds over the NE Pacific - are reproduced globally, and confirmed in other models..
If we assume that they are, it is pertinent to ask what the implications are vis-a-vis solar radiation management geoengineering schemes. If, as with our cloud albedo enhancement scheme, the idea is - as far as possible - to stabilise the Earth's average surface temperature, probably at current values, by varying the cooling in concert with the warming, the cloud cover / temperature positive feedback relationship would not come in to play. If, for any reason, we wished to produce an overall smallish cooling - for example to cool ocean waters in order to try to reduce the energy of hurricanes that subsequently form in those regions - the positive feedback should reinforce the geo-engineered cooling. So Steve should not sigh too deeply. All Best, John. Quoting Alvia Gaskill <agask...@nc.rr.com>: > > From reading the paper, it seems that the reason for less clouds with higher > SST due to CO2 forcing is due in part to a much quieter ocean, i.e., less > wind and less waves. The way that CCN from DMS from marine bacteria and > salt particles get into the atmosphere is in part due to breaking of waves. > If you heat the water gently, without disturbing it, you may get more water > vapor into the atmosphere, but without the accompanying CCN. Better put > some big assed propellers on those cloud boats, Salter as your mission may > have just been expanded. > > > ----- Original Message ----- > From: "Tom Wigley" <wig...@ucar.edu> > To: <s.sal...@ed.ac.uk> > Cc: "Climate Intervention" <climateintervent...@googlegroups.com>; > "geoengineering" <geoengineering@googlegroups.com> > Sent: Sunday, July 26, 2009 6:07 AM > Subject: [geo] Re: [clim] Yet another positive feedback > > >> >> The real issue is the total magnitude of feedbacks, as >> characterized by (e.g.) the equilibrium global-mean warming >> for 2xCO2 (DT2x). >> >> The breakdown of the feedbacks is not directly relevant to >> this -- although it is of interest in model validation. >> >> This paper tells us nothing about DT2x or its uncertainty. >> My comment -- so what. >> >> Tom. >> >> +++++++++++++++++ >> >> Stephen Salter wrote: >>> Hi All >>> >>> Science July 24 from >>> http://www.sciencemag.org/cgi/reprint/325/5939/460.pdf has a >>> something about a positive feedback between sea temperature and cloud >>> cover. I had thought that warmer seas would increase evaporation and so >>> cloud cover but drying them out seems to win. >>> >>> Sigh. >>> >>> Stephen >>> >> >> >> >> > > > > > > -- John Latham lat...@ucar.edu & john.latha...@manchester.ac.uk Tel. 303-444-2429 (H) & 303-497-8182 (W) --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
