Face it: Most of us are fossil-fuel junkies, and that's not gonna change anytime soon. Enter Columbia University physicist and engineer Klaus Lackner, of Tucson-based Global Research Technologies, who's currently developing a "carbon air trap" system, the idea being to outfit vast rural fields and other places with large filters that would gather carbon in the air, pump it into subterranean reservoirs, and sell it. Critics charge that costs for such a setup would be enormous and that energy requirements are unrealistic. But Lackner counters that governments may put a price on captured carbon and that new technologies could allow the carbon to be pumped to factories where it would be converted to synthetic fuel, closing the carbon loop. A pre-prototype filter has been built, and GRT plans to have a working field up within the next few years. Says Lackner, "This is not an idea you can prove except by doing."

1. VEXING ISSUE: The average U.S. car spews about 6,000 pounds of CO2 into the atmosphere annually. Roughly 40 percent of the 51.7 trillion pounds of CO2 emitted globally every year comes from big polluters like transportation and agriculture, the rest from point sources like power plants, where CO2 could easily be captured before leaving the smokestack.

2. REMOTE ACCESS: Carbon-capture devices need not be in close proximity to polluting sources. A field in west Texas could capture emissions from, say, a Rio-to-Paris nonstop, traffic in Jakarta, and a Beijing steel factory. It's all in the mix.

3. SUCKING WIND: Surfaces coated with a sorbent will trap CO2 in the air. Water running past will wash the mixture to a tank, where the sorbent can be separated from the CO2 by electrolysis and then recycled. After separation, the CO2 will be piped off to be compressed and pumped down into sealed reservoirs miles below—and put on the market.