The paper under discussion is either in press or close to being in press at Climate Dynamics with G Bala as first author.
Because of Clausius-Claperyon, one expects precipitation to increase with heating and decrease with cooling. So you would expect a CO2 induced warming to increase precipitation and a cloud-whitening induced cooling to decrease precipitation. Relative to the 2xCO2 case we do find that cloud whitening reduces precipitation. However, it reduces it preferentially over the oceans, and over land it does not reduce it as much as the CO2 increased it. So, in our simulations with 2xCO2 and unrealistically large and uniform amounts of marine cloud whitening, relative to the 1xCO2 case, there is a decrease in precipitation over the oceans and an increase over land. Significantly, even though, relative to the 2xCO2 case there is a decrease in precipitation over land, there is an even greater decrease in evaporation over land, so on average soils are moister and there is an increase in runoff. So, there does seem to be an error in Erika's story (which could have been entirely the result of my having misspoken). ___________________________________________________ Ken Caldeira Carnegie Institution Dept of Global Ecology 260 Panama Street, Stanford, CA 94305 USA +1 650 704 7212 [email protected] http://dge.stanford.edu/labs/caldeiralab @kencaldeira On Fri, May 28, 2010 at 8:51 AM, Stephen Salter <[email protected]> wrote: > Erika > > In your geoengineering article in Science news due out on 5 June you quote > Ken Caldeira as saying that cloud brightening would decrease rainfall over > land. Alan Robock has collected evidence to show that this has been observed > in volcanic historical eruptions and it has been predicted for stratospheric > aerosols. > > However a paper by Bala and others, including Caldeira, says the opposite > is the case for cloud brightening. Their final paragraph reads > > /In summary, prior studies have suggested that offsetting global warming by > reflecting sunlight to space would result in a drying of the continents. In > contrast, our study indicates that reflecting sunlight to space by reducing > cloud droplet size over the oceans could lead, on average, to a moistening > of the continents. > > /The Bala paper is too big to attach to an email but you can download a > copy from the root of the file below my signature. > > The difference is very important and your article could affect decisions on > research funding. May I ask you to look into the matter? > > Stephen Salter > / > / > > Emeritus Professor of Engineering Design > School of Engineering and Electronics > University of Edinburgh > Mayfield Road > Edinburgh EH9 3JL > Scotland > tel +44 131 650 5704 > fax +44 131 650 5702 > Mobile 07795 203 195 > [email protected] > http://www.see.ed.ac.uk/~shs <http://www.see.ed.ac.uk/%7Eshs> > > > Erika Engelhaupt wrote: > >> >> My feature story on geoengineering is out in the June 5 issue of Science >> News, which you should be receiving a complimentary copy of in the mail. In >> the meantime, here is a link to the online version, where you can also see >> the illustration featured on our cover: >> >> >> http://www.sciencenews.org/index/feature/activity/view/id/59391/title/Engineering_a_cooler_Earth >> >> (A better view of the cover is up on /Science News/’ Facebook site: >> http://www.facebook.com/#!/photo.php?pid=4002108&id=35695491869<http://www.facebook.com/#%21/photo.php?pid=4002108&id=35695491869>< >> http://www.facebook.com/#%21/photo.php?pid=4002108&id=35695491869> ) >> >> >> /Science News/ is now also available on select Barnes & Noble and Borders >> newsstands nationwide, although I’m not sure if they’ve received the new >> issue quite yet. >> >> I hope you enjoy the story and find that I’ve balanced the issues >> fairly—there was much more that I would have liked to have included if I’d >> had more space. >> >> Best regards, >> >> Erika >> >> Erika Engelhaupt >> >> Deputy News Editor >> >> /Science News/// >> >> > -- > The University of Edinburgh is a charitable body, registered in > Scotland, with registration number SC005336. > > -- > You received this message because you are subscribed to the Google Groups > "Climate Intervention" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<climateintervention%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/climateintervention?hl=en. > > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
