U.N. General Assembly President Nassir Abdulaziz Al-Nasser, United Nations Secretary General Ban Ki-Moon, Brazilian President Dilma Rousseff, Brazil's Secretary of the Conference Luis Figueiredo Machado and Rio+20 Secretary General Sha Zukang attend the closing ceremony of the Conference on Sustainable Development in Rio de Janeiro on Friday. Andre Penner/AP hide caption

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Shell says it hopes to never need to use its new 300-foot-long, $100 million oil recovery ship named Nanuq for anything other than drills and training. Richard Harris/NPR hide caption

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United Nations Secretary-General Ban Ki-moon speaks during a news conference on June 7 at the United Nations headquarters in New York City. Ban wants to focus on making energy available to the poorest populations of the world. Andrew Burton/Getty Images hide caption

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When a raindrop hits a mosquito, the mosquito and drop join together, and the mosquito rides the drop for about a thousandth of a second before its wings, which act like kites, pull it out of the water. CDC Public Health Image Library hide caption

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A Tokyo sushi restaurant displays blocks of fat meat tuna cut out from a 269kg bluefin tuna. Yoshikazu Tsuno/AFP/Getty Images hide caption

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Researcher Hans Roy opens a core sample taken from the bottom of the Pacific Ocean. A core sample like this one contained bacteria that settled on the seafloor 86 million years ago. Bo Barker Jorgensen/Science/AAAS hide caption

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Layers of earthquake-twisted ground are seen where the 14 freeway crosses the San Andreas Fault near Palmdale, Calif. The San Andreas Fault, like the kind that caused the huge earthquake off the coast of Indonesia, is a strike-slip fault, where the tectonic plates slide past each other. David McNew/Getty Images hide caption

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The statue of Freedom, atop of the U.S. Capitol Building, is pictured against a "supermoon" on March 19, 2011. Jewel Samad/AFP/Getty Images hide caption

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Researchers studying Greenland's ice say it is melting more slowlyl than previously thought. Here, ice travels down a relatively small outlet glacier into the sea. Ian Joughin/Science/AAAS hide caption

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Germany plans to take all of its nuclear power plants offline by 2022, which means coal-fired power plants like the Kraftwerk Westfalen, in Hamm, Germany, will be a key component of the country's energy infrastructure. Lars Baron/Getty Images hide caption

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In this undated picture, Mount Everest, the world's tallest mountain at 29,029 feet, stands behind the Khumbu Glacier, one of the longest glaciers in the world. Nepal has more than 2,300 glacial lakes, and experts say at least 20 are in danger of bursting. Subel Bhandari/AFP/Getty Images hide caption

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A robotic arm breaks off a chunk of mineral-rich rock deep underwater. Nautilus Minerals of Australia hopes to develop and expand undersea mining by extracting copper, gold, silver and zinc from the seafloor. Nautilus Minerals hide caption

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Researchers have analyzed the fossil imprints of of raindrops, like the ones shown here, to study the atmosphere of the Earth, as it was 2.7 billion years ago. The rule at the top is 5 centimeters, or about 2 inches, long. W. Alterman/University of Pretoria hide caption

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A drilling rig sits on Oooguruk Island off the coast of Alaska's North Slope. The 6-acre island was built by Pioneer Natural Resources so it could drill for oil on the Arctic Ocean. Steve Quinn/AP hide caption

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F. Sherwood Rowland, pictured here in 1989, was one of three chemists who shared the 1995 Nobel Prize for chemistry for work on discovering chemicals that deplete the Earth's ozone layer. University of California/AP hide caption

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