Hello All, As JohnN says, marine cloud brightening is, in principle, a viable, quantitatively adequate alternative to stratospheric seeding, and I think that possibility should definitely be looked into.
However, Ken Caldeira has suggested an interesting variation, which is that these two geoengineering schemes could perhaps be deployed in concert, the stratospheric scheme providing a general cooling, and the cloud brightening technique providing localised fine tuning, which is possible because not all clouds need to be seeded, and judicious choices as to where to cool can therefore be made. Such a combination (or perhaps cloud brightening alone) could, for the above reasons, possibly ameliorate or eliminate the Amazonian problem. I should add that fully-coupled atomosphere/ocean GCM computations by Phil Rasch and Jack Chen, indicate that the cloud brightening scheme produces its maximum cooling in the Polar regions. Cheers, John. Quoting John Nissen <j...@cloudworld.co.uk>: > > Hi all, > > Recently the geoengineering group discussed the pros and cons of solar > radiation management (aka SRM geoengineering) using stratospheric > aerosols in the Arctic [1]. > > A possible downside of more widespread deployment of stratospheric > aerosols has come to light; it is from decreased rainfall on Amazon > [2]. Some of us were already concerned by possible slight weakening of > monsoons. > > This decreased rainfall is liable to be aggravated by the growing El > Nino. (The last strong one was in 1998.) > > Yet some experts (e.g. Jeff Ridley) are saying that deployment in the > Arctic will not be sufficient to save the sea ice. (And if the sea ice > goes, the methane could come out of permafrost, Greenland ice sheet > disintegrate, etc.) > > And Alan Gadain, from the University of Leeds was warning me, last week > [3], that Arctic deployment wouldn't work, yet on the other hand an > effect of more general deployment would be to cool the Arctic. > > Who is right, and what should we do? > > Could there be a way to protect Amazon and elsewhere from reduced > rainfall, while deploying stratospheric aerosols at a range of latitudes > to produce both widespread cooling effect and specific cooling in the > Arctic? > > We could use marine cloud brightening rather than stratospheric > aerosols, because the risk of undesirable side effects is smaller and > because the technique can be applied locally, but do we have the luxury > of time to develop the technique? The Arctic sea ice is liable to > disappear more rapidly than anyone expected - we just cannot predict > with any certainty. Likewise the Amazon rainforest could perish if > there were consecutive years of drought - which we cannot predict. > > Isn't there an overwhelming case for some kind of experimental trial of > stratospheric aerosols in the Arctic, preferably starting next spring, > before El Nino effects set in? There is so much at stake, wouldn't it > be stupid to delay? > > And shouldn't some significant funding be put into marine cloud brightening? > > Cheers from Chiswick, > > John > > [1] "Balancing the pros and cons of geoengineering" thread: > http://groups.google.com/group/geoengineering/browse_thread/thread/b045b6428fc89a93/95b940c3c3352e35?#95b940c3c3352e35 > > [2] Aerosol effects investigated by Met Office: > http://www.metoffice.gov.uk/corporate/pressoffice/2009/pr20090604.html > > [3] Geoengineering seminar at the House of Commons, 15th July 2009. > > > > > > -- 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 -~----------~----~----~----~------~----~------~--~---
