OK, rather than being Plan B I certainly agree that activities like sulfate injection should be Plan Y or Z for climate relief.
I think you’re missing the best plan, though, for removing excess CO2 from the atmosphere — the time-tested natural process of photosynthesis. One of the ways we’ve generated that CO2 is by oxidizing the organic matter and microbes in the soil through deforestation, plowing and burning land, filling wetlands and generally running roughshod over the verdant earth we once inherited. In addition to raising CO2 levels, we have dehydrated the earth by this destruction. Now the soil is so lifeless and compacted that rainfall on land in drought as in Texas can’t soak in, but just runs off as a flash flood. What a tragic irony!
Repairing landscapes to hold more carbon in the soil, and to hold water with healthy vegetation, is a win-win. Doesn’t it deserve mention as a practical and proven method of “geoengineering”?