So let's see.... suspending particles in the atmosphere with no tested long-term effects, possible medical consequences, possible food chain consequences, perhaps they stay aloft for decades or centuries blocking sunlight, an actual solar minimum occurs to (along with suspended particles) create unendurable winters, possible drought, possible famine....

And the Deep Thinkers (Billy Gates included) conclude, "SURE, why not give it a go?"

I'm reminded of the words of H.L. Mencken: The urge to save humanity is almost always only a false-face for the urge to rule it. Power is what all messiahs really seek: not the chance to serve. This is true even of the pious brethren who carry the gospel to foreign parts.

― H.L. Mencken