4.2 Suitable Locations
Given the potential advantages from surface albedo enhancement, what are the suitable areas that could be modified to obtain beneficial effects on a scale large enough to offset some or all of the additional radiative forcing due to GHGs and the higher temperatures that are expected?
Several proposals have been made to increase surface albedo to reduce radiative forcing effects. These include using both the ocean and land as well as existing polar ice. In our opinion, the ideal candidate location(s) for albedo enhancement must satisfy all of the following criteria:
4-3
(1) It must be a land mass. Oceans and other watery bodies have the lowest albedos on the planet, but are too unstable to support any kind of covering. Thus, proposals to cover parts of the ocean (10% for a doubling of carbon dioxide from pre-industrial levels to 550 ppmv) with floating reflective solids or spheres are not practical (17, 53). The cover materials would probably wash ashore, damage sea life and eventually become covered with algae or bacteria that would darken them and reduce their reflectivity. Other proposals to apply a film or foam to the surface (111) or to haul icebergs to warmer waters are equally impractical.
(2) It must be largely uninhabited so as not to interfere with human life.
(3) It must have no significant potential for crop production, grazing, mining or development of other natural resources, since the land beneath the covering cannot be exposed. Thus, croplands, grasslands and forests are unsuitable. Increasing the albedo of existing or new vegetation by horticulture or spray-on coatings with clays is impractical on the scale needed (17).
(4) Related to (3) above, the location must be largely devoid of all vegetation and relatively biologically unproductive to avoid interference with removal of atmospheric carbon dioxide by trees and other land plants.
(5) It must have a low year-round albedo. Ideally, this would be 0.1- 0.3 to yield the maximum gain in reflected solar radiation from covering with an artificial reflective surface. This rules out areas seasonally or permanently covered by snow such as the polar regions and the Arctic tundra.
(6) It must have a high flux of solar radiation and few cloudy days to maximize the effectiveness of the surface covering. Such areas are found near the equator. Desert areas receive almost twice as much solar radiation as humid regions at the same latitude and due to the lack of cloud cover, lose (re-radiate) almost twice as much heat by night (112).
(7) The air above the location must have as low a water vapor content as possible to minimize absorption of downwelling solar radiation.
(8) The location must be a relatively flat and stable surface. This excludes for the time being mountains and sand dunes.
