My hunch on the science side (take this with a grain of salt, I’m a computer scientist in climate informatics, not a climate scientist) is that there will surely be undesired effects. I’m working on method development for identifying all of the downstream impacts, but it’s low TRL. I think we’ll end up needing to weigh the negative with the positive impacts unless we find some miracle silver bullet. Intervening in a system as complex as our climate makes it a good bet there will be undesirable impacts.
My guess is we’re ~10 years from confident estimations of what is/isn’t a good idea. Then we have to convince governments to act. That’s really slow. The marginally good news is, perhaps the right intervention can cool the earth fast enough (possibly at the cost of something like Ozone).
That said, we are already intervening in the climate with greenhouse gases. The safest intervention from here is to just stop/slow that. We know what the world is like with less GHG. We only get one shot at a habitable Earth, so while it is scary to try fixing it, it’s more scary to continue breaking it in my opinion. No one wants to act hastily though, we’re working on the science to make sure we know what we’re doing.