................................ "Cheaper to fix the cause , than the effect."
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That is the whole question, isn't it? Bjorn Lomborg(amongst others) sees mitigation when and as needed, as being way cheaper than a massive program of dubious effect at horrendous cost to fix a possible non problem.
The problem is that when the money starts lining up behind a story, any story, then the story gets legs. As soon as the first geoengineering contracts are let there'll be no way back.