Educate the public on the hazards of coal and the fact that nuclear power is by far the safest source of electricity available.   This may not seem like geoengineering, but if the average American had understood the truth about coal and nuclear in 1950, coal company propaganda would never have gotten them to reject nuclear in favor of coal and we would not be in a climate crisis now.   Coal contains uranium, arsenic and cancer causing benzene. Nuclear fuel can be recycled.   Please read all of the attachments carefully before dismissing this suggestion.  If you do read the attachments, you will understand that the above is correct.   Nuclear power could have saved us and still can, the only problem is false beliefs caused by coal industry propaganda. Educating the public by teaching them the attached is the most cost effective geoengineering possible.