Further to Alan, presumably perturbing 10,000km^2 is meant top affect a larger area: if cloud seeding only cools the areas where the clouds are seeded, without advective transport cooling other places, it's going to be of very limited use to people who aren'#t sailors....
On Sep 28, 4:52 am, Alan Robock <[email protected]> wrote: > Dear John, > > If you only do it for a few days, how will you detect a signal? And how do > you know that perturbing 10,000 km2 will not affect a larger area? > > Alan Robock, Professor II (Distinguished Professor) > Department of Environmental Sciences > Rutgers University > 14 College Farm Road > New Brunswick, NJ 08901 > > [email protected]http://www.envsci.rutgers.edu/~robock/ > Sent from my iPhone. +1-732-881-1610 > > On Sep 27, 2010, at 11:44 PM, John Latham <[email protected]> > wrote: > > > Hello Alan and colleagues, > > I agree with you, Alan, that mounting a comprehensive field study of the > > climatological ramifications of the deployment of SRM schemes would be a > > mammoth, highly protracted and perhaps impossible endeavour, but I would > > like to make the point that field-testing of the cloud brightening > > geoengineering idea could be undertaken without significant climatogical > > repercussions. > > A limited area (say 100 x 100 km) field experiment designed to assess the > > quantitative viability of this SRM scheme (and at the same time to examine > > aerosol-cloud interactions using advertently generated seawater aerosol) > > could be conducted without climatically damaging effects since the lifetime > > of the generated aerosol in the marine boundary layer is a few days. Such a > > study would be very similar to and no more complex than the highly > > successful international VOCALS field study of marine stratocumulus clouds > > conducted in 2008 off Chile & Peru, and directed by Rob Wood of the > > University of Washington. > > All Best, John. > > > Quoting Alan Robock <[email protected]>: > > > > Dear Ken, > > > > I think you are being rather picky with words. In any case, I never > > > said it cannot be tested. I said it cannot be fully tested in a > > > real-world in situ experiment without full-scale implementation, > > > because the climate signal will be drowned out by chaotic climate > > > variations and because injecting into a pristine stratosphere cannot > > > test injecting into an existing cloud. Of course computers can be > > > used for testing. That is what I do, and I advocate much more of it. > > > The statement below refers to in situ experimentation. > > > > Alan > > > > Alan Robock, Professor II (Distinguished Professor) > > > Editor, Reviews of Geophysics > > > Director, Meteorology Undergraduate Program > > > Department of Environmental Sciences Phone: +1-732-932-9800 x6222 > > > Rutgers University Fax: +1-732-932-8644 > > > 14 College Farm Road E-mail: [email protected] > > > New Brunswick, NJ 08901-8551 USA http://envsci.rutgers.edu/~robock > > > > On 9/27/2010 12:00 PM, Ken Caldeira wrote: > > >> Folks, > > > >> Robock et al and Fleming have both asserted that "geoengineering > > >> cannot be tested". > > > >> Robock et al (Science, 2010): /"We argue that geoengineering cannot > > >> be tested without full-scale implementation."/ > > >> Fleming (Slate): "/Global climate engineering is untested and > > >> untestable.../" > > > >> These statements seem either trivially true or patently false, > > >> depending on interpretation. > > > >> *Trivially true:* /If the only thing that you are willing to > > >> consider a test is the thing itself, then trivially there is no test > > >> other than the thing itself./ > > > >> *Patently false:* /There are many tests that can be done that can > > >> help us understand possible consequences of a geoengineering > > >> deployment./ > > > >> One could imagine someone saying in the United States in the 1950's, > > >> "There is no way you can test the proposed interstate highway > > >> system, because you will not understand all its effects until it has > > >> been deployed." This is true, in the sense that you could not > > >> predict in advance detailed effects that the interstate highway > > >> system would have on the spread of suburbia, traffic jams, the rise > > >> of the SUV, and so on. > > > >> But, in the 1950's they could have tested the concrete, built a > > >> small stretch of road and learned about its construction and use > > >> etc. Would we say "/The interstate highway system cannot be tested > > >> without full-scale implementation?/" Would we say "T/he interstate > > >> highway system is untested and untestable?/" I think we would say, > > >> "There are plenty of tests we can do, but of course we will not > > >> understand the full consequences of our implementation until the > > >> implementation is complete." > > > >> We perform tests to improve our understanding. We never have full > > >> understanding of consequences of our actions before we act. We > > >> hopefully act in ways that will have the greatest rational > > >> expectation of positive outcomes. We do research to avoid having > > >> rational expectations that do not accord with facts on the ground. > > > >> Many people have regarded Mt Pinatubo as performing a natural > > >> experiment of geoengineering -- a test of the idea of solar > > >> radiation management. Like all tests, Mt Pinatubo was not a perfect > > >> test (e.g., the aersols were not maintained in the stratosphere, > > >> etc). Nevertheless, Mt Pinatubo has functioned as a natural test of > > >> some of the concepts underlying solar radiation management. > > > >> In 2003, Alan Robock wrote a paper called "Introduction: Mt. > > >> Pinatubo as a test of climate feedback mechanisms". > > >> (http://climate.envsci.rutgers.edu/pdf/VEAChapter1_Robocknew.pdf). > > >> How is it logically possible that Mt Pinatubo could function as a > > >> test of climate feedback mechanisms, but not of geoengineering (ie > > >> SRM), when those climate feedback mechanisms are central to the > > >> climate system response to any geoengineering effort? > > > >> Furthermore, hasn't Alan claimed to have tested geoengineering > > >> concepts in his climate models and found them wanting? How can you > > >> have it both ways: testing geoengineering concepts and claiming the > > >> concepts are untestable? > > > >> The list of possible useful geoengineering tests could be a long > > >> one, and includes tests of small scale physics, climate model > > >> simulations, observations of climate variability, ecosystem > > >> experiments, observations of behavior of natural or introduced > > >> particles on stratospheric transport and chemistry, small scale or > > >> short-term deployments, etc. (I am not advocating all of these, just > > >> listing them.) > > > >> It seems odd, when there are a number of people eager to perform a > > >> wide range of tests on geoengineering concepts, to have a small > > >> minority claiming that these concepts simply can't be tested > > >> (especially when members of that minority have themselves been > > >> involved in testing geoengineering concepts). > > > >> So, do the people who say that "geoengineering can't be tested" mean > > >> something that is both true and substantive (i.e., couldn't also > > >> have been said of, for example, the development of the US interstate > > >> highway system)? If so, it would be interesting to hear what this > > >> non-trivial interpretation might be. > > >> Best, > > > >> Ken > > > >> ___________________________________________________ > > >> Ken Caldeira > > > >> Carnegie Institution Dept of Global Ecology > > >> 260 Panama Street, Stanford, CA 94305 USA > > >> +1 650 704 7212 [email protected] > > >> <mailto:[email protected]> > > >>http://dge.stanford.edu/labs/caldeirala...@kencaldeira > > >> -- > > >> 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. > > > > -- > > > 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. > > > -- > > 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. 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