Mother Nature Network: A new proposal from the Environmental Protection Agency (EPA) turns the spotlight on emissions from the energy sector, proposing that power companies reduce their carbon dioxide emissions by 30 percent by 2030, compared to 2005 levels. As Gina McCarthy, administrator for the EPA, explains in the video above, it's an attempt to give states a flexible path to reaching the lofty goal instead of a one-size-fits-all approach. "The flexibility of our Clean Power Plan affords states the choices that...