For this theoretical physicist here it seemed actually very simple. It’s a conservation law. If you take carbon out of the ground and you put it into the system it will stay there unless you take it back out. From a societal perspective, this is much much more complicated because as we fix it there will be winners and losers.
Solar geoengineering rests on a simple idea that it is technically possible to make the Earth a little more reflective so that it absorbs a little less sunlight, which would partly counteract some of the risks that come from accumulating carbon dioxide in the atmosphere. When I say technically possible, it appears that at least doing this in a crude way is actually easy, in the sense that it could be done with commercial off-the-shelf technologies now, and it could be done at a cost that is really trivial, sort of a part in a thousand or a part in ten thousand of global GDP.