Iranian President Mahmoud Ahmadinejad waves in Pakdasht, southeast of Tehran, Nov. 23. Ahmadinejad on Wednesday said he was surprised at European moves to isolate Tehran's central bank. HO/Reuters/Landov hide caption

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A drilling rig looms behind a barn in Tioga County, Pa. Scott Detrow/StateImpact Pennsylvania hide caption

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SolarCity has received financing from Bank of America Merrill Lynch to install solar electricity systems on houses on military bases, like one here at Soaring Heights Communities at Davis Monthan Air Force Base outside Tucson, Ariz. Lend Lease hide caption

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DJ Patil explains a visualization of a person's LinkedIn network, where different groups of contacts are illustrated by different colors. Patil developed big data projects for LinkedIn — like algorithms to determine whom you might know. He now recruits mathematicians for a venture capital firm. Joi Ito/Flickr hide caption

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Key provisions of the Kyoto Protocol expire in December of 2012, and experts say there's no real global framework in place to replace the treaty that was supposed to be the first step toward ambitious actions on climate change. Above, a coal-fired power plant in eastern China. China is now the leading carbon dioxide emitter in the world. AFP/Getty Images hide caption

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The U.S. is second only to China in emitting gases that cause global warming. Above, the smoke stacks at American Electric Power's Mountaineer power plant in West Virginia. Saul Loeb/AFP/Getty Images hide caption

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The compact car-sized Mars Science Laboratory is due to land on the red planet on Aug. 6, 2012. It is equipped with a suite of instruments to study rocks and soils, and take other measurements. NASA/JPL-Caltech hide caption

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