In September Britain’s Royal Society, one of the world’s most sober-minded scientific bodies, released a study on "geoengineering." A few years ago such ideas would have been considered crazy. Geoengineering was the realm of whacked-out paranoids obsessed with "contrails" and propeller-head tech geeks with no grasp of politics or economics. But the changes associated with a warmer world–polar ice melt, desertification and ocean acidification–are happening faster than predicted. At the same time, political efforts at climate change mitigation–such as the Copenhagen talks–are making very little progress. So scientists are rethinking the unthinkable: technological schemes to reshape the earth’s climate, no matter how risky or expensive, are officially on the table.

Typically, geoengineering ideas range from deploying a massive fleet of sun-reflecting mirrors into orbit to filling the oceans with iron shavings that would trigger carbon-eating algae blooms. Scientists have even taken inspiration from the global cooling that followed a 1991 volcanic eruption in which 20 million tons of sun-diffusing ash entered the atmosphere. They are now exploring whether injecting sulfur into the atmosphere could lower the planet’s thermostat.

But of all the ideas that are being considered, carbon capture and sequestration stands out because it might, just might, not be totally nuts. CCS involves a complicated process through which carbon dioxide is removed from fuels like coal and oil–or even from the air–and is then forced into spent oil wells, porous rock formations or under the ocean floor for long-term storage. Already there are a smattering of small CCS projects around the world. Most of them involve oil companies that pump CO2 into active oil wells to help force up more petroleum in a practice known as enhanced oil recovery. A few companies use the CO2 for industrial purposes, like carbonation of drinks.

A combination of available technologies are used to capture CO2 before it escapes into the atmosphere. Postcombustion scrubs CO2 from coal, gas or oil smoke after the fuel is burned; then, through the manipulation of temperature and pressure, the CO2 is absorbed with solvents and recovered for storage. The technology is extremely expensive, but it has proven effective in retrofitted and new facilities. Precombustion capture, also called Integrated Gasification Combined Cycle technology, involves essentially cooking coal into a gas from which the CO2 is easily stripped away and captured. In either case, the capture of CO2 requires huge amounts of additional energy. Coal can also be burned in a process called oxy-fuel combustion, which captures more CO2 than the other options mentioned here but is not compatible with older facilities and can be used efficiently only on new plants.

Also gaining attention is a technology designed to go after CO2 already in the air–with the aid of artificial trees that imitate the carbon-capturing abilities of real ones. Klaus Lackner, a geophysicist at Columbia University, has invented a form of resin that absorbs CO2 when air passes through the material. Initial tests show that this technology is extremely effective at pulling CO2 from the air and that the biomimetic "trees" could be installed anywhere, ideally by the thousands, much like a wind farm. Since there are already such high concentrations of CO2 in the air, these "trees" would not need to be installed near a specific source and would instead capture emissions from airplanes, cars and other decentralized emitters. Lackner believes that each of his devices could remove one ton of CO2 per day, which, he says, is 1,000 times faster than a real tree. The cost per "tree" is estimated at around $30,000 and doesn’t use excessive amounts of energy, says Lackner.

There is also a cutting-edge technology called "mineral storage," which can sequester dangerous CO2 gas into safe, inert solids. Scientists at Columbia University recently discovered that a type of peridotite rock that exists in Oman, New Guinea, California and other places naturally captures vast quantities of CO2 by pulling it from the air and transforming the gas into mineral solids–calcium carbonate and magnesium carbonate. But does enough peridotite rock exist to make a real difference? And how would captured CO2 be delivered to these rocks?

But the real question for any of these methods–beyond who would organize and pay for them–is what to do with the CO2 after it is captured. For one thing, leaks could be lethal–concentrated CO2 asphyxiates. A natural version of this happened in Cameroon in 1986 after a volcanic eruption caused the bottom of Lake Nyos to belch out a cloud of CO2, killing 1,700 people and hundreds of cattle over a range of twenty-five kilometers.

If CCS goes commercial, the storage of this dangerous gas would need to be regulated–a prospect that does not exactly excite energy producers. "What I heard industry saying is that they don’t want to be compelled to do real-time monitoring…and they don’t want a public process," says Lee Sprague, who manages the Clean Energy Campaign for the Michigan chapter of the Sierra Club. He says communities need to become engaged when a CCS project is under consideration and make sure public health and safety officials are prepared for potential emergencies.

Whatever the combination of technologies, CCS on a large scale would be fabulously expensive. And it would have a meaningful impact on the climate only if it were an adjunct to rapid industrial transformation away from fossil fuels toward a clean-energy economy.

The biggest problem with CCS is not so much its expensive, experimental, high-tech aspects but the twisted political discourse surrounding it. These days CCS functions as a canard, a misleading ruse, set afloat by the coal industry to greenwash its image. Billboards around Appalachia read, "Coal: cleaner greener power for the people and protection for the environment." The political class happily falls in line behind the marketing because coal states are swing states. As a result, candidates from both major parties bloviate about their commitment to "clean coal"–a thing that manifestly does not exist. CCS also offers middle-class consumers the salve of hope: it suggests that we can carry on with our profligate ways–that we can have our fossil fuel and burn it too.

For these reasons, most radical environmentalists reject CCS technology as unworkable–and a distraction from the real issue of cutting emissions. Greenpeace has been especially ardent in its denunciation. But the Environmental Defense Fund has lobbied on behalf of CCS, and the World Wildlife Fund and Sierra Club remain equivocal. Meanwhile, Energy Secretary Steven Chu is considering its merits. The Energy Department is backing further research and development of CCS with hopes of seeing commercial deployment within the next ten years. Among green luminaries, NASA’s chief climate scientist, James Hansen, is known to have suggested that CCS might have some use, though he remains focused on a larger goal: an international moratorium on coal power.

As the climate shifts and warms, Arctic ice melts–releasing massive amounts of methane, a hugely powerful greenhouse gas that is twenty times more damaging than CO2. This in turn accelerates global warming, which drives the melting in the Arctic. After a certain point, emissions reductions will be unable to counter such fierce positive feedback loops. In light of such sobering facts, CCS has become a topic of increasing interest among those thinking through the climate challenge.

The world’s leading politicians like to say that an atmospheric CO2 concentration of 450 parts per million is the tipping point. But most climate scientists, including Hansen, believe the real threshold is 350 ppm. The really bad news is we are already at 390 ppm and increasing by 2 ppm per year. Because CO2 lingers in the atmosphere for at least 100 years, even a total and immediate cessation of all emissions would not be enough to arrest dangerous warming trends. And the best-case scenario that might come from Copenhagen will not come anywhere close to what we need. As the world’s mitigation efforts plod along, CCS could provide triage, allowing us to adapt to a more chaotic climate, and for high-energy users like the United States and China to make the transition to a low-carbon economy.

For now, the Obama administration is restarting the once canceled public-private partnership FutureGen, which promises near zero emissions from gasified coal in Mattoon, Illinois. Once operational, this $1.5 billion pilot project would be the first commercial-scale CCS facility in the country. As it turns out, a report released by the House of Representatives in March found that "FutureGen appears to have been nothing more than a public relations ploy for Bush Administration officials to make it appear to the public and the world that the United States was doing something to address global warming despite its refusal to ratify the Kyoto Protocol." In other words, whereas the former administration had no interest in CCS except for greenwashing purposes, President Obama is inclined to give it a try. But even if FutureGen 2.0 takes off, it will power only 150,000 homes, which breaks down to a cost of $10,000 per home!

Meanwhile, in 2010 the Energy Department expects to spend nearly $180 million on site selection, permits, community outreach, technological innovation and testing of current CCS technologies, plus $41 million more focused on innovations at existing coal plants using precombustion technologies. In addition, the American Recovery and Reinvestment Act of 2009 provides $3.4 billion for CCS-related programs, including funding for the Clean Coal Power Initiative, carbon capture and energy-efficiency improvement projects, geologic sequestration training and research grants.

In Congress, the Waxman-Markey bill in the House and the Kerry-Boxer bill in the Senate are being referred to as "climate legislation," though each is a confusing mix of green jobs, subsidies to the fossil fuel industry, proposed offsets, weak targets for emission reductions, inadequate support for renewable energy and efficiency measures, and funding for CCS research and deployment. Waxman-Markey would create a quasi-governmental Carbon Storage Research Corporation with a board made up of representatives from rural electric cooperatives, public utilities, fossil fuel producers and nonprofit environmental groups, among others. This body would be charged with initiating CCS demonstration and deployment projects, and promoting its commercial adoption. The bill also proposes a tax on users of fossil fuel electricity that would generate $1 billion annually to be used on CCS projects. The greater goal of the bill is to invest $60 billion in CCS technology by 2025. Waxman-Markey also proposes that any coal plants built between 2009 and 2020 employ CCS as it becomes available. By 2025, all plants built after 2009 would have to be retrofitted to capture at least 50 percent of their CO2 output, with the capture target rising over time. Sounds good–on paper. However, energy companies are unlikely to accept the additional costs associated with retrofitting for CCS, and industry backers are no doubt already hard at work trying to persuade legislators to weaken provisions or kill the bill outright.

If implemented, could Waxman-Markey or Kerry-Boxer or their hybrid really create industrial-scale CCS? If all plants built after 2009 eventually had to sequester half of the carbon they emitted, would that have much impact? A study by the Norwegian NGO Bellona set out to discover the potential of this technology and found that CCS could eventually capture 236 billion tons of CO2–or 33 percent of global emissions– by 2050. Yet much about CCS is speculative, and there may be years of expensive research to do before it will even begin to make good on its promises. For now, the usual suspects remain deeply invested in cheap fossil fuels and the massive subsidies these fuels receive. CCS remains on the horizon, a shimmering, blurry possibility, and a mirage-like suggestion of hope that we can pull back to somewhere below 350 ppm of atmospheric CO2 concentrations before it is too late.

CCS is not the solution to the climate crisis. As one proponent of geoengineering admitted, it "is simply a temporary ‘stay of execution.’ We will still have to work for a pardon." And that comes in only one form: radically and rapidly reducing emissions.