This is the year the "dam of denial" will break and the momentum for climate action will become an unstoppable flood. It will be messy, confusing and endlessly debated but with historical hindsight, 2015 will be the year. The year the world turned, primarily because the market woke up to the economic threat posed by climate change and the economic opportunity in the inevitable decline of fossil fuels. That shift will in turn unlock government policy and public opinion because the previous resistance to action argued on economic grounds, will reverse to favour action on economic grounds.