How would the world react if one nation launched a photo voltaic geoengineering challenge to chill the planet with out the permission of others? Would the sky change color based mostly on the kind of particles injected into the higher environment? Even when international common temperatures cooled in response, how would rainfall change over Africa? These are simply a few of the questions on photo voltaic geoengineering scientists grappled with at a December assembly of the American Geophysical Union (AGU) in Washington DC, they usually…