Calling All Mad Scientists

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Each tower would extract about one ton of carbon dioxide a day, so it would take an awful lot of towers to scrub the 80 million tons we emit daily. The sheer scale of the problem dwarfs any single solution, but in Broecker and Kunzig's view, Lackner's invention is "the only hope." Their reasoning is simple: the towers can be placed anywhere -- far easier and more practical than attaching a CO2 scrubber to every car and airplane on the planet. And because CO2 disperses quickly through the entire atmosphere, removing it in one spot helps the whole world.

By contrast, say Broecker and Kunzig, collecting CO2 from the flues of power plants would entail transporting the gas perhaps hundreds of miles to a dumping ground. Nevertheless, this too promises to be an important means for steering us from the path of doom, should we manage to make it happen. In January, the Department of Energy scrapped plans for FutureGen, a coal-fired plant that was to collect and dispose of its own CO2 emissions.

The Norwegian oil company Statoil currently captures CO2 from its drilling operations at the Sleipner natural gas field in the North Sea, and it then injects a million tons of the gas each year under the seabed. There are plenty of other places to put the heat-trapping gas. Iceland, for example, is made entirely of basalt, a volcanic rock rich in calcium silicates, which bind with CO2. This fall, Reykjavik Energy plans to begin pumping carbon dioxide half a mile deep into basalt deposits. Vast banks of basalt also exist elsewhere: in the United States, volcanic rock covers more than 60,000 square miles of Washington, Idaho, and Oregon.

Detractors will inevitably dub such schemes misguided or deluded. Tim Flannery, for one, argues in his 2005 book, The Weather Makers, that the volume of carbon dioxide we create is "so prodigious that it seems impossible for Earth to tuck it away without suffering fatal indigestion." The authors of Fixing Climate are not oblivious to the scale of the problem or the expense of the solution. If we choose Lackner's original proposal, then large mounds of carbonate must be piled or buried somewhere. That would transform the landscape, but so would covering hundreds of square miles with solar panels. "There is no free lunch in solving the CO2 problem," Broecker and Kunzig say.

As for Lackner's current proposal to array carbon-capturing towers across the globe, they admit that it sounds utopian. "If the amount [of CO2] the world produced in a single year were spread over Manhattan, it would rise three-quarters of the way up the Empire State Building. On the other hand, if all the wastewater produced in the United States alone were spread over Manhattan, even the radio antenna on top of the Empire State would be far beneath the waves. Yet somehow in the twentieth century we managed to get our sewage problem under control." With our own Great Stink now threatening to overpower the entire planet, we owe it to ourselves and our descendants to consider the merits of such ambitious technological fixes before we suffocate in our own stifling waste.