An elaborate plan to use Antarctican conditions to suck CO2 out of the air has been proposed, using the high winds to create wind power, which would power giant freezers. In the freezers, pressurized air would press CO2 into a liquid that would then sublimate into snow when ejected. The wind turbine's power wouldn't be very useful for other things, since maybe 200 scientists live in Antarctica. As time went on, this freezer and compressor would suck the carbon from the air, and leave it locked forever in the snow.
Of course, being who I am, I couldn't help but imagine a potential improvement in this plan. Snow falls very slowly in Antarctica on account of it being technically a desert. What little snow does fall remains as ice for a millennia, so I could use this to lower the ocean. To our wind-freezer system, we add a desalinization plant. Ocean water is pumped through huge pipes up from the ocean, using wind power. Under intense pressure, fresh water accumulates on the other side of semipermeable membranes. This fresh water is then sprayed towards the pole. In the freezing conditions of Antarctica, even boiling water tossed into the air will quickly solidify into snow. Thousands of years worth of snow will fall every single day, preferably on top of the dry ice snow that we were creating. As this accumulates, the sea level slowly drops, saving countless low elevation communities around the globe.
Of course, Slashdot poster gman003 found a minor rub with the whole thing:
The only thing I see stopping it is politics. In particular, America and China. Europe seems to at least recognize the need for action, and they're willing to work together to try things. China is generally too selfish and shortsighted to worry about the environment, but you could probably convince them if you could make it somewhat-profitable for them (just have the wind turbines and such made in China, that should satisfy them).
But then it falls on to America. And you're going to need America at least not fighting this plan, because if the US decides to actively fight it, it's not happening. Period. You'd also need them to at least chip in a good chunk of the funding if you're going to do the full plan, make a serious dent in CO2. Problem is, denying the very existence global warming is a political requirement for half the country. They'll fight it just on principle, and I can't see the rest of the country fighting back for a project that doesn't have any immediate gains for the US specifically. While some sort of "compromise" could probably pull it off, or with luck it could be swept under the rug and never become a political issue, that's not guaranteed.
Still, it's the best plan I've seen so far.
There's no need for it to necessarily be government funded though, and I could definitely see American green charities paying for it, European engineers designing it, and Chinese engineers physically assembling it in place.