[topynate]

Space-based geoengineering is technically superior to stratospheric aerosol injection, but the latter is practical almost immediately, and is likely to be much cheaper no matter what. In my view that outweighs concerns about the ozone layer.

It has also been pointed out that launching enough space-shades with chemical rockets would itself deposit a considerable amount of particulate matter in the upper atmosphere, so to be really atmospherically 'clean', one would need to complement geoengineering with a radical new launch technology.