The world needs to stop emitting carbon: it needs to get to ‘net zero’. The arguments are about how, and by when – but they’re fierce. Environmental groups say we need to get there as quickly as possible and if we have to completely rethink our lifestyles to do it, so be it. Most governments and big businesses agree on the target, but they’re cautious: how do our economies survive? How does society hold together if we try to de-carbonise overnight? In this series Tortoise – in partnership with BP – talks to campaigners, businesses, academics and members of the public about the most important question of our time.