well, it's this, this is the alan robach point. once deployed, the effects of solar radiation management on the earth would be difficult to isolate from the effects of natural variability and, indeed, from the effects of human-induced global warming. it would take, it's estimated or guessed, at least a decade of full deployment of sulfate aerosol spraying before enough data became available to judge confidently whether the solar field was working at planned. if alan robach is right in this objection, i think this fact would drive a dagger into the heart of of david keith's ramp-up scheme which, as i said, aims to slow warming by a fraction of a degree centigrade. if it would take a decade to generate the data needed to assess the impact of full deployment of sulfur aerosol spraying, it would take much longer or with david's proposal to start slowly and go halfway. so with no decipherable information coming in, we would be flying blind for a very long time. and so i think the scheme that david proposes in his new book fails the thir