The disturbing imagery of blocking the sun to slow climate change aside, geoengineering faces serious practical concerns. The Economist looks at the ups and downs of this radical solution. "Increasingly, the question asked about any scheme to alter the climate in a way that acts to counter greenhouse warming—by scattering sulphates in the stratosphere to cut down incoming sunlight, for example—has been 'whose hand will be on the thermostat?' The assumption has been that while geoengineering schemes might help some people and places they will harm others, and that this will lead to inequity and conflict."