David Attenborough and a panel of influential thinkers on the natural world join Tom Heap to preview this month’s Climate Summit in Paris. Can the world’s leaders come to an agreement to save a warming planet? The director of Titanic, Avatar and Terminator, James Cameron tells Tom that a vegan diet can slash our carbon emissions. Former Australian Prime Minister, Kevin Rudd recalls what went wrong at the last climate summit in Copenhagen and explains why he’s so much more hopeful of real commitments on carbon emissions from the Paris meeting. David MacKay, the government’s chief scientific advisor on energy policy until 2014, tells Tom that Europe’s renewable energy policy is unfit for purpose and David Attenborough raises the thorny issue of our rising population. Producer: Alasdair Cross.