The idea of reflecting sunlight in order to a lower the planetary temperature is not new. The idea is sound, though it would be an incomplete solution to the problem of global warming if carbon emissions remain as they are: sure, the temperature might decrease, but the carbon dioxide would still chemically alter the environment. The oceans would continue to acidify, for instance. And if the temperature issue is abated by reflection, the drive to decarbonize would drop, so the Chinese and Indians would continue to crank out coal plants, and the US would continue to fail to build nuclear powerplants.
Still, adding reflecting aerosols to the upper atmosphere or even glitter out in space would be useful at a certain level. There are negatives with each approach: one of the easiest, adding sulfur dioxide to the upper atmosphere by spraying it from jetliners, would result in some amount of acid rain. But something I see all too often: “the attempt to reflect sunlight will result in a new ice age.” This is, of course, nonsense. The amount of sunlight that would need to be reflect would be *vast,* while any attempt to reflect that much would start at a far lower level and sloooowly ramp up to that level. The effects, both positive and negative, would take a long time too accrue, and the process could be adjusted to account for things.
Some reflection ideas seem not only easier but more practical than others. In regions that are much more beset by summer heat than winter cold, simply painting black roofs white would not only aid in the cooling of the planet but the cooling of the building directly. Alternatively, cover black roofs with black solar panels: you don’t affect reflection, but you reduce the need for solar farms elsewhere that would replace bright dirt with dark solar panels.
Additionally, ground-level reflection strategies that cover anything but asphalt had better be done at sea. From space, the darkest areas of Earth are asphalt and deep oceans; covering the sea, especially near the equator, with reflective stuff would be more effective than covering lighter dirt, rock or especially sand in higher latitudes. I’ve even seen people float the idea of adding reflectants (like vast white insulating blankets) to high latitude glaciers. While that might add some small benefit for the glacier, that same white blanket would do far better work spread out over the surface of the Pacific near Indonesia.
A program to do enough of this sort of thing to effectively counter global warming would need to be a multi-national effort. The US going about it alone would be not only unlikely to be terribly effective, it would be an economic hit to the US, leaving the actual big polluters off the hook. but on the other hand, I’m less than thrilled about the idea of Chinese aircraft spraying crap into the air.
