An oil well in Garden City, Texas. With prices plunging, oil companies are laying off thousands of workers. Spencer Platt/Getty Images hide caption

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A functioning oil rig sits in front of the capital building in Oklahoma City, Okla. The oil industry is an important employer in the state, but officials are concerned a technique used to dispose of wastewater from oil extraction is behind a surge in earthquakes here. Frank Morris/KCUR hide caption

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Scientists published the first global survey of the known undersea freshwater reserves. Water is relatively cheap now, but the reserves could be valuable if it becomes scarcer in the future. Olivier Morin/AFP/Getty Images hide caption

itoggle caption Olivier Morin/AFP/Getty Images