> I say it's both. Just like it's not transportation vs. power, or
> temperate grasslands vs. tropical forests. If we're going to keep
> ourselves from baking and/or drowning, every CO2 molecule must be
> squeezed!
I went to a talk the other day by an oceanographer who had gone into the geoengineering business, I forget what flavor. A commonly cited study of carbon reduction wedges manages to balance economy-wide savings from unexploited efficiencies with expenses from more active approaches like carbon sequestration. Everything is supposed to be enough to keep CO2 down enough to restrict global average temperature rise to 2C. Thing is, CO2 outputs seem to be exceeding the BAU scenarios, and it's beginning to look like greenhouse gas targets will have to be lower to avoid a system flip. So there might have to be bigger and more wedges for a happy ending. Granted that she has a dog or two in the fight, but it's consistent with what I've been picking up.
She pointed out that most geoscientists dislike talking about geoengineering. We have a shaky grasp of what's already been going on, so trying to direct the outcome by adding more variables feels ill-considered, to say the least. But we might have to at least research the possibilities.
There was a sort of "Oh, hell" air among the grad students at the reception.
-- Andy