Inside Veolia Energy's Plant Three in Baltimore, blue pipes carry chilled water that will be sent out to cool nearby buildings. The green pipes carry condensed water that removes heat from the chilling system, and orange pipes carry a refrigerant. The yellow pipes are for a future cooling system. Mike Ruocco/NPR hide caption

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Retired Coast Guard Adm. Thad Allen testifies Monday before the commission investigating the Gulf of Mexico oil spill. Though Allen was the government's leader of the spill response, he acknowledged it was not always clear to the public who was in charge. Mark Wilson/Getty Images hide caption

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Bayou Bienvenue in New Orleans is an example of south Louisiana’s wetland loss. Fifty years ago, this was a productive freshwater marsh with cypress and tupelo trees. Today, stumps are all that remain, as saltwater has encroached inland. Debbie Elliot/NPR hide caption

itoggle caption Debbie Elliot/NPR

A slice of Hurricane Karl was captured by NASA's CloudSat satellite. The clouds were just over 8 miles high. hide caption

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Wildlife biologist Anthony Fischbach observes a tagged walrus near Point Lay, Alaska, earlier this month. Tens of thousands of walruses have come ashore in northwest Alaska because the sea ice they normally rest on has melted. U.S. Geological Survey/AP hide caption

itoggle caption U.S. Geological Survey/AP

A male Florida panther walks down Jane's Scenic Drive in Fakahatchee Strand Preserve State Park. Before scientists bred the Florida panthers with cats from Texas, they lacked vitality and were near extinction. Science/AAAS hide caption

itoggle caption Science/AAAS

This handout photo from New Zealand's Department of Conservation shows one of 40 pilot whales that died after beaching themselves at Spirits Bay, northwest of Auckland. Department of Conservation/Getty Images hide caption

itoggle caption Department of Conservation/Getty Images