* * * 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/caldeiralab @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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