re: carbon sequestration
Rather than telepathy I relied on the fact that you, Jim, didn't mention carbon sequestration, and one can't have a discussion about AGW here without people falling over themselves to demand a massive nuclear power program that would have to be government subsidized.
As for cost, sequestration seems much more promising than your "exoatmospheric" approach (please tell me that's not solar shades you're talking about, but even solar satellites are pie in the sky). And what the heck is your technological approach to the ionosphere? That's a new one for me.