Geo-engineering freaks me out

Via Environmental Capital:

The Copenhagen Consensus, an outfit organized by “skeptical environmentalist” Bjorn Lomborg, just released a bunch of new papers seeking to answer the question: Would a technological fix for rising temperatures be cheaper and easier than the cat-herding that makes up today’s global climate-change talks?

... On paper at least, climate engineering looks fantastically attractive. For a tiny fraction of the cost of curbing global greenhouse-gas emissions, which lead to global warming, scientists could tinker with the atmosphere and avoid the worst effects of climate change.

Just spraying droplets of sea water to make bigger, whiter clouds, for instance, would reflect enough of the sun’s rays to limit future temperature increases—and it would be ridiculously cheap to do, bringing trillions of dollars of future benefits for a trifling investment today.

I must say, the planet is so complex, and the probability of unintended consequences so high, the prospect of geo-engineering is very scary to me. The cost benefit analysis looks promising, but keep in mind we're talking about VERY long tails here.