United Press International: Paris is planning to introduce a carbon tax — a controversial move that could significantly boost energy efficiency behavior in France. Championed by French President Nicolas Sarkozy, the carbon tax is part of Paris’ plan to slash greenhouse gas emissions, combat climate change and become less dependent on fuel imports. To be placed on transport and household fuels, the tax is due to come into effect next year, with its exact scale under intense debate. Prime Minister Francois …