US President Barack Obama has unveiled what he called "the biggest, most important step we have ever taken" in tackling climate change. The aim of the revised Clean Power Plan is to cut greenhouse gas emissions from US power stations by nearly a third within 15 years. The measures will place significant emphasis on wind and solar power and other renewable energy sources. However, opponents in the energy industry have vowed to fight the plan…The revised plan will aim to cut carbon emissions from the power sector by 32% by 2030, compared with 2005 levels…It sets carbon pollution reduction goals for power plants and requires states to implement plans to meet goals. States have until September 2016 to submit plans, but must comply by 2022…Mr Obama said the new limits were backed up by decades of data showing that without action the world faced more extreme weather and escalating health problems…Power stations are the largest source of greenhouse gases in the US and account for about one third of all such US emissions…