"2040" is not a sophisticated film, nor is it original, the ideas and arguments all having been developed by others. It’s not meant to be either of those things – engaging, persuasive and urgent, it’s an exercise in what you might call muscular hope. Filmamker, Damon Gameau's eco-commentary operates on a knife edge: if you’re critical of government policy, you’re derided as an Eeyore; constructive, you’re a nutty utopian. Gameau dances the middle path, outlining the intractable issue - carbon from transport, waste, farming, energy and ignorance - before focusing exclusively on two surprising solutions that deploy existing technology and address the climate crisis - things that are doable.