http://www.futurismic.com/2006/10/new_column_jamais_cascio_on_th.html
This is a swell Jamais Cascio article on doing terrible things to the atmosphere in an attempt to avert the terrible things we've already done to the atmosphere.
Any society that would set off hydrogen bombs in the atmosphere (which we're already done, repeatedly) would be willing to try something like this – if things got hairy enough. In fact, it wouldn't even take a "society" to do it – you get a few ultra-rich computer moguls with private space programs, and they could salt the stratosphere with sulfur out of the petty cash.
