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In time, huge solar mirrors five or more miles in diameter may be used to reflect radiation of the sun to specific areas on earth to increase evaporation and to prevent crop-killing frosts.
Wayback Machine 1958: Geoengineering
We have shown quite a few wild and crazy geoengineering ideas before, but it appears that they go way back. Fifty years Arthur Radebaugh proposed it for heating, not cooling: