Volcanic sulfuric acid in the upper atmosphere is not the only known factor that can reduce global average temperatures. Another well known phenomenon is that d

Volcanic sulfuric acid in the upper atmosphere is not the only known factor that can reduce global average temperatures. Another well known phenomenon is that during the ice ages, the sprawling white ice sheets tended to reflect a lot of the solar radiation back into space, causing a positive feedback loop that cooled the planet down even further. The fundamental idea here in both cases, is that the global warming is caused by the blocking of the warm Earth's long-wavelength black body radiation by the greenhouse gases. But the same greenhouse gases aren't as effective at blocking the short-wavelength radiations coming off of the reflective surfaces. If you're going take the absurd route of a planet-wide ecosystem engineering project, why not increase the albedo of the planet instead by covering a portion of its surface with thin, light, semi-transparent, semi-reflective films that we already know how to make? We already cover huge areas with artificial materials like cement, asphalt and paints. Since they just lie around motionless on the ground, they're easy to deploy, easy to maintain, and easy to modify or remove if something doesn't go according to plans. Why instead throw aerosols at huge logistic costs into the stratosphere where the air currents and aerosol dispersion patterns are difficult to predict and even more difficult to manage if something goes wrong? Why do people promote these sorts of unwieldy sci-fi fantasies (high-speed rail vs hyperloop, anyone?), instead of addressing the fundamental cause at the least cost possible? You know, may be convince everyone that dumping so much CO2 into the atmosphere is not a good idea? Climate change is primarily rooted in politics and greed. That would be a good place to start. And if possible at all, find a way to absorb some of the CO2 back? Nature actually has some mechanisms that can absorb and sink CO2 in huge quantities. Getting them to work for us is a challenge. But I don't think it's worse than the hubris of imagining being powerful enough to control the planet altogether.