Taken from the Article
As my colleague Tim McDonnell explained back when the NAS study was released:
Albedo modification would [use] airplanes or rockets to deliver loads of sulfate aerosols into the stratosphere, where they would bounce sunlight back into space. But if the technology is straightforward, the consequences are anything but.
The aerosols fall out of the air after a matter of years, so they would need to be continually replaced. And if we continued to burn fossil fuels, ever more aerosols would be needed to offset the warming from the additional CO2. [University of California-San Diego scientist Lynn] Russell said that artificially blocking sunlight would have unknown consequences for photosynthesis by plants and phytoplankton, and that high concentrations of sulfate aerosols could produce acid rain. Moreover, if we one day suddenly ceased an albedo modification program, it could cause rapid global warming as the climate adjusts to all the built-up CO2. For these reasons, the report warns that it would be "irrational and irresponsible to implement sustained albedo modification without also pursuing emissions mitigation, carbon dioxide removal, or both."
This is exactly what I mentioned earlier. There is no doubt that the world is warming, however, cloud seeding with chemicals such as the aerosol stuff would more than likely cause more/other problems. It is simply a huge risk that may or may not actually help the earth, this is a final solution in case of a huge heating phenomenon that I don't even think would happen in our life time, not to mention the earth could get even hotter during this cloud cover initially from all the C02 staying in the atmosphere. I still do not think one stream would cause anything to change on a global perspective. The earth pollutes trillions of C02/water vapor/methane not only from plants and our oceans, but from volcanoes as well. Humans only make up roughly 2-3% or less of the total C02 emissions. While humans may cause the earth to be warming a little faster. The only true thing we could actually do is lower emissions and cease the release of harmful chemicals into the atmosphere. Cloud seeding on a grand scale would either have very harmful effects, or it wouldn't do anything at all.
The earth does what the earth does. Mother nature is a force not to mess with. The earth works in crazy ways and I simply do not believe any man made proposals, besides cutting down emissions, will actually do anything to stop the earth from going through cycles. Global Warming is not an easy thing to stop. look at 10,000 years ago during an ice age. First the earth had to go through massive global freezing, and then go through a massive global warming. Humans weren't even contributing to that one bit. This cycle lasted over a thousand years. You have to consider that the earth goes through cycles just like everything else. It has been through global freezing and cooling for millions of years. A single stream of aerosol isn't going to effect that very much.