Based on our record of environmental interventions; SO2 sounds suicidal. But it only lasts a few days in the atmosphere so maybe it has an in built off switch.
Note that is for the stratosphere, not the atmosphere.
The mechanism is well known from volcanic eruptions, and it only lasts (from memory) 1-2 years in the stratosphere, so if something goes wrong, it can easily be tapered off.
The mechanism is well known from volcanic eruptions, and it only lasts (from memory) 1-2 years in the stratosphere, so if something goes wrong, it can easily be tapered off.