I think everybody who has thought much about it has similar concerns. I'd propose we start soon, start small, ramp up slowly, and be thorough about the data collection.

As uncomfortable as it is to experiment on the only planet you have, even worse would be to wait too long and then, in a panic, try to do everything that might possibly work all at once and to as extreme a degree as possible.

Iron enrichment of the ocean seems to have fallen in popularity compared to atmospheric aerosolizing, but the iron enrichment seems less risky to me. I agree that it seems better to start now, start small, and collect as much data as possible to understand all the subtle dynamics in play. That seems better than holding off for twenty years and then going big in a desperate hurry.

Once there will be a business around this and people will make money the businesses will maintain a lobby to keep doing it and even increase the operation.