Cost analysis of stratospheric albedo modification delivery systems
> We conclude that (a) the basic technological capability to deliver material to the stratosphere at million tonne per year rates exists today, (b) based on prior literature, a few million tonnes per year would be sufficient to alter radiative forcing by an amount roughly equivalent to the growth of anticipated greenhouse gas forcing over the next half century, and that (c) several different methods could possibly deliver this quantity for less than $8B per year. [1]
Benefits, risks, and costs of stratospheric geoengineering
> Using existing U.S. military fighter and tanker planes, the annual costs of injecting aerosol precursors into the lower stratosphere would be several billion dollars.
[0] https://en.wikipedia.org/wiki/Climate_engineering#Costs
[1] https://iopscience.iop.org/article/10.1088/1748-9326/7/3/034...
[2] https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/200...