Interesting stuff. Has anyone looked at plugging in the Biome modelling of Vizy et al into the geoengineered-world GCMs? I'd be very interested to see if geoeng protected, or hastened the demise of the Amazon TRF. We would look a bit silly if we tried to save the world and we torched the Amazon by accident - releasing a few GTC into the atmosphere, and causing a minor mass extinction in the process. Definitely some negative PR potential there. A
2009/7/21 John Latham <[email protected]> > 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 <[email protected]>: > > > > 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 > > [email protected] & [email protected] > > 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 [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 -~----------~----~----~----~------~----~------~--~---
