I'm a researcher, working on renewable energy for a prominent technology development organization. I have to say we missed the boat as far as climate change goes; our present energy infrastructure (and the developing energy infrastructure of China and India) make vast and continuing emissions of CO2 inevitable in the next 50 to 100 years. It is not realistic to assume that any practical approach will allow us to continue the extremely rapid growth of economies in Asia and South Asia while simultaneously reducing emissions. Really, in order for that to occur, China would have to be commissioning one nuclear plant per week, instead of the coal-fired power plants they are currently commissioning on a weekly basis.

It is possible, however, that we can control further heating of the planet by driving dust into the stratosphere. Stratospheric winds travel around the planet at speeds in excess of 100 miles per hour, and naval artillery shells or rockets could be used to propel payloads of combustible material up into this atmospheric layer. The amount of mass needed is small, relative to the effect produced, since small solid particulates, only a few nanometers or microns across, tend to nucleate the formation of water droplets, which can be much larger than the particles themselves. This cloud of dust and droplets would reflect a measurable and predictable amount of the sun's light. A similar effect was documented after the eruption of Mount Pinatubo, though the effect only lasted for about one year. This is a technically-feasible approach, and should be seriously investigated by the US and other industrial nations.