1. A model is not an empirical test. The claim in Science is about the latter not the former.
2. The analogy is the interstate system is not apt - these are examples of modular or encapsulated phenomena that can be tested in relative isolation, just in the way a medication can be tested on a human subject in isolation from other humans. For more on this distinction and its implications see my article in the edition of ERL (which you co-edited): http://dx.doi.org/10.1088/1748-9326/4/4/045104 . MB From: [email protected] [mailto:[email protected]] On Behalf Of Ken Caldeira Sent: Monday, September 27, 2010 10:11 AM To: [email protected] Cc: geoengineering Subject: Re: [geo] Can solar radiation management be tested? Robock et al (Science, 2010) made a categorical statement which is false: "geoengineering cannot be tested without full-scale implementation." This statement has no more validity than "the interstate highway system cannot be tested without full-scale implementation". Full-scale implementation provides the most complete test, but it is not the only test. Your comments below seem to recognize not only the ability to test in models, but the potential of improving the reliability of these tests. On Mon, Sep 27, 2010 at 10:00 AM, Martin Bunzl <[email protected]> wrote: As you well know, the reliability of our current climate models at the local level needs improvement. As such any such claims should be approached with healthy skepticism. Point 2 below is consistent with adopting such a skeptical attitude. The only way to short cut the timetable on low density insertion would be to massively invest in improvements in the power and accuracy of our climate models at the local level. From: Ken Caldeira [mailto:[email protected]] Sent: Monday, September 27, 2010 9:52 AM To: [email protected] Cc: geoengineering Subject: Re: [geo] Can solar radiation management be tested? But didn't Robock et al claim to gain knowledge about untoward local precip effects from tests using climate models? Robock, Alan, Luke Oman, and Georgiy Stenchikov, 2008: Regional climate responses to geoengineering with tropical and Arctic SO2 injections. J. Geophys. Res., 113, D16101, doi:10.1029/2008JD010050. In the light of this, what is the meaning of phrases such as: "We argue that geoengineering cannot be tested without full-scale implementation." Robock is busy testing geoengineering in his day-to-day work. Obviously, testing the thing itself yields more information than testing something other than the thing itself, but the statement (of which you are co-author) is false as it stands, because there are tests that can be (and have been) performed without full-scale implementation. On Mon, Sep 27, 2010 at 9:15 AM, Martin Bunzl <[email protected]> wrote: 1. Almost nobody disputes the value of technical experiments to see for example, how to deliver SO2 and the like. 2. Almost everyone agrees that short of planetary wide insertion, it would be very hard to gain knowledge about untoward local effect (especially in re precip.) 3. Some people suggest that we could get reliable planetary-wide data re point 2. if we did a low intensity insertion for long enough - say 30 years. Martin Bunzl From: [email protected] [mailto:[email protected]] On Behalf Of Ken Caldeira Sent: Monday, September 27, 2010 9:00 AM To: geoengineering Subject: [geo] Can solar radiation management be tested? 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 "The 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] 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.
