John The Met. Office statement at
http://www.metoffice.gov.uk/corporate/pressoffice/2009/pr20090604.html did not mention that the Jones Haywood Boucher results were based on treating just 3.3 % of the earth's surface. One of the the areas treated in the South Pacific off Chile and Peru. It would be interesting to know if treating the other side of the Pacific would produce the opposite effect and if a judicious balance between the two could achieve any desired beneficial result. It was unfortunate that this was not done. Perhaps it soon will be. Because of the log term in the Twomey effect we get much better cooling for a given spraying effort with a lower dose over a large area than with the high local concentration used in their paper. While it may be scientifically interesting to model an extreme case it would not have been possible to confine the spray to such an extent. Even so, the predicted cooling for treating the small area was equivalent to the cancellation of all damage since pre-industrial times. The Met. Office statement did not mention the prediction by Jones et al. of increased precipitation in drought-stricken regions of sub-Saharan Africa, northern India and eastern Australia. Stephen 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 John Nissen wrote: > 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. > > > > > > > -- 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 "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 -~----------~----~----~----~------~----~------~--~---
