Reducing Trapped Radiation: Albedo Modification from Space
A second set of albedo modification proposals tread somewhat in the realm of science fiction. These proposals would reflect radiation from space rather than from within the earth’s atmosphere. The idea is that a fleet of reflective shields (basically like mirrors) would be deployed in low orbit. The shields would increase the earth’s albedo by ensuring that some amount of the sun’s radiation never makes it into the atmosphere in the first place. These ideas are highly speculative and almost certainly very expensive – in the hundreds of billions of dollars at least – but on the other hand, we do have lots of experience with launching satellites and other devices that sit successfully in the earth’s orbit.
Also in the highly-speculative realm of albedo modification strategies would be to increase the reflectivity of the oceans in certain areas through the transportation of icebergs (ocean ice has roughly six times the albedo of the ocean as a whole). Oceanic albedo could also be increased by placing reflectors on the ocean surface (similarly to space-based reflectors), but in practice, this would be difficult and would have some undesirable environmental side effects.