将CO2从空气中分离储存以稳定气候

Emerging techniques to pull carbon dioxide from the air and store it away to stabilize the climate may become increasingly important as the planet tips into a state of potentially dangerous warming, researchers from Columbia University's Earth Institute argue in a paper out this week. The upfront（预付的） costs of directly taking carbon out of the air will likely be expensive, but such technology may well become cheaper as it develops and becomes more widely used, and cost should not be a deterrent（威慑，妨碍物） to developing such a potentially valuable tool, the authors said.

The techniques would address sources of CO2 that other types of carbon capture and storage cannot, and have the potential to even lower the amount of CO2 in the atmosphere -- significant because the world may already have crossed beyond the point where the climate can be stabilized by just limiting emissions.

"The field of carbon sequestration（封存，固定） , the field of capture and storage as a community is too timid when it comes to new ideas," said lead author Klaus Lackner, director of the Lenfest Center for Sustainable Energy. "You cannot rule out new technology simply because the current implementation is too expensive."

Lackner and his colleagues at the Lenfest Center, part of the Earth Institute, summarize the technical and financial obstacles facing direct air capture of carbon in the review paper, "Urgency of development of CO2 capture from ambient air," published in the journal Proceedings of the National Academy of Sciences. Lackner has been working on the problem for more than a decade, and he founded a company in 2004 to work toward commercializing the techniques.

Various methods are being developed to extract CO2 directly from stationary sources such as coal-fired power facilities and steel and cement manufacturing plants, storing the CO2 underground or using it for other purposes, such as feeding algae farms to produce biofuel. But these systems do not address the problem of emissions from mobile sources such as cars, trucks and airplanes.

CO2 in the atmosphere, building up from humans' burning of fossil fuels and other activities, has led to warmer average temperatures across the globe, melting ice sheets and glaciers, raising sea levels and producing more frequent extreme weather events. Nine of the 10 warmest years in the modern meteorological record, since 1880, have occurred since 2000; the first six months of 2012 were the 11th warmest on record, based on land and ocean surface temperature measurements, according to the National Oceanic and Atmospheric Administration and the National Climatic Data Center.