But what WE are doing is unsustainable, and we will not be doing it much longer.  So yes, OUR civilization will go, will COLLAPSE--whether we like it or not...

I agree that it isn't sustainable, and I don't expect it to last long by historic standards, or even by human-lifetime standards. Collapse is possible, but what I think more likely is a radical transformation (for better or worse) driven by increasingly powerful technologies. Self-destruction is one possibility, but not quite the same as collapse.

...its capability for harm is at least as great as for good, and depends critically on who studies it and implements it and when.

Yes. My main reason for bringing up this topic is that, a week ago, I realised that there may well be a "who", "when", and "why", and that we need to give this careful thought before it gets much higher on the public radar screen.

...A world thick with smog but kept just barely cool enough by heavy doses of stratospheric SO2, which must be perpetually increased as CO2 loading of the atmosphere continues, until we find effects from precipitating SO2 (acid rain returns) becoming important.

The numbers say that along an endlessly-increasing-fix path, acidity caused by SO2 would always be much less than that caused by CO2. The oceans would still acidify.

...you are wrong to imply that this can be continued indefinitely, and that to oppose it is to be pro-warming.

I'm sorry, I didn't intend to imply that it could continue indefinitely. I do think that, if the facts look as they do now, and if the debate slides in the direction that scares me, the label "pro-warming" could be made to stick.

I suspect there is a good reason to oppose stratospheric SO2 injection intuitively.  And should we find un-intuitive, logical and fact-based reasons?  That is a good idea.

Intense, sceptical evaluation is vital. I think there will be no problem in getting this to happen, however, because I can't imagine anything going forward before climate scientists model it inside-out and critics raise every imaginable objection, both good and bad. So, I recommend calling loudly for study, expecting to get it, and proceeding on that assumption.

What I'm encouraging here is that we consider which advocacy positions will and won't make sense, depending on what the facts seem to be at the time. I see pitfalls here that need to be clearly recognised and avoided.

Words and ideas I offer here may be used freely and without attribution.