Should we actively attempt to manipulate the earth's climate?

This Rolling Stone article describes an interesting potential solution to the global climate change problem:

Wood's proposal was not technologically complex. It's based on the idea, well-proven by atmospheric scientists, that volcano eruptions alter the climate for months by loading the skies with tiny particles that act as mini-reflectors, shading out sunlight and cooling the Earth. Why not apply the same principles to saving the Arctic? Getting the particles into the stratosphere wouldn't be a problem -- you could generate them easily enough by burning sulfur, then dumping the particles out of high-flying 747s, spraying them into the sky with long hoses or even shooting them up there with naval artillery. They'd be invisible to the naked eye, Wood argued, and harmless to the environment. Depending on the number of particles you injected, you could not only stabilize Greenland's polar ice -- you could actually grow it. Results would be quick: If you started spraying particles into the stratosphere tomorrow, you'd see changes in the ice within a few months. And if it worked over the Arctic, it would be simple enough to expand the program to encompass the rest of the planet. In effect, you could create a global thermostat, one that people could dial up or down to suit their needs (or the needs of polar bears).

(HT: Crooks and Liars) I seem to recall reading somewhere that during the Cold War, John Von Neumann (inventor of the architecture of the modern computer) proposed that the US should use climatological warfare to cause crop failure in the USSR, and to be ready with countermeasures if they tried to do the same thing to us. I'd much rather see such manipulations done for the benefit of the world, rather than as a form of warfare. But of course such attempts make one nervous.

I think the law of unintended consequences could come into play in a huge way here. Given that the world climate is a chaotic system, who knows what such a manipulation might trigger? But if it looks like the alternative is a 20-foot increase in world-wide sea levels, I'd say try spraying the particles.