using solar geoengineering to offset carbon dioxide levels of five hundred and sixty parts per million—levels that could easily be reached later this century—determined it would change the appearance of the sky. White would become the new blue. The effect, they noted, would cause “the sky over formerly pristine areas to look similar to the sky over urban areas.” Another, more felicitous result, they observed, would be glorious sunsets, “similar to those seen after large volcanic eruptions.”
