[sfnhltb]

SO2 injection is just such a bad idea it is scary there are still people talking about it. The problem is even if you ignore the nasty side effects, as CO2 carries on rising you have to inject more and more SO2 every year to counter the increased CO2 (especially combined with SO2's much lower residence time in the atmosphere being in the range of a few days/weeks instead of CO2 being measured in centuries).

It would also tie us in - if SO2 stopped being injected into the atmosphere for any reason, all the CO2 is still there and as the SO2 washes out of the atmosphere within a few weeks, the CO2 warming would come back full force immediately - the longer SO2 had been used to offset CO2, the worse it would be.

Offsetting CO2 warming with a seperate cooling effect is risky, the real solutions are either reduction of CO2 output - and even that might not be enough for many countries/cities because of the decades of delays in any meaningful action that have been engineered since we knew what was happening - or some technology to pull CO2 out of the atmosphere.