Ken, It is clear that the absolute statement from Robock, et al is not literally correct.
But we need to discuss the real issue. There is a need to describe proposed protocols that set forth a defensible sequence of field testing that addresses a) how each stage will provide useful information about potential impacts of subsequent larger scale tests; and b) where each proposed test is accompanied by a rigorous showing that the proposed test is not likely to result in any serious consequences itself. My hunch is that we will be better able to develop such protocols only after more lab scale tests and model based analyses have been performed. Personally, I think funding those initial levels of activity would be sensible as the next step. David From: [email protected] [mailto:[email protected]] On Behalf Of Ken Caldeira Sent: Wednesday, September 29, 2010 7:02 PM To: geoengineering Subject: Re: [geo] Re: Can solar radiation management be tested? Robock et al (Science, 2010): "We argue that geoengineering cannot be tested without full-scale implementation." Fleming (Slate, 2010): "Global climate engineering is untested and untestable..." In summarizing this conversation, it seems universally agreed that flat statements like these are simply untenable, in that everyone acknowledges that there are many tests that can be done (both in the real world and in numerical simulations) that will help improve our ability to predict consequences of deployments of climate intervention systems. (Couldn't someone equally argue that "climate consequences of emissions reductions are untestable" ?) As with all large scale deployments in complex systems (c.f., electricity generation and transmission, highway systems) there is no way prior to full-scale system deployment to be able to predict all consequences of that deployment. Nevertheless, there are a large number of things that can be done to improve our predictive ability. It is clear that we need either good models or lots of time with mid-sized-tests to predict climate consequences of a full-scale deployment with confidence.. This state of affairs makes it clear that we should be working hard to improve and test climate models and to conduct field experiments that can improve process representations in those models. As Stephen Salter points out, there are many things to be tested beside large-scale climate consequences. Alan Robock and co-authors may feel they knows what they meant when they wrote those words, but I think what they meant was not what they wrote. It seems to me that the content of their statement is something like: "If we are unwilling to rely on climate models and are unwilling to spend decades doing mid-sized tests in the environment, then there is no way to test the climate consequences of geoengineering schemes without full-scale implementation." To understand large scale climate consequences of a geoengineering deployment, we will most likely need to rely on climate models, and I think that is what Robock et al meant to say. There are plenty of tests we can do in the field (e.g., testing hardware, tests aimed at improving physical process understanding and improving representations of those processes in the models). We can test climate model performance using a wide variety of observations (e.g., Mt Pinatubo). We can also test various climate intervention proposals in climate models (and our trust in those results of those tests should increase as models improve and are evaluated on a broader range of measures). It is damaging to efforts to conduct these climate engineering tests to have people going around saying things like "geongineering cannot be tested without full-scale implementation" when this statement is clearly wrong as written: there are many valuable tests that can be done, both in the real world and in models. ___________________________________________________ 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 "Marriage cannot be tested without full-scale implementation." -- 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.
