We're living in 'The Anthropocene', the epoch in which humans have the biggest impact on the condition of the globe. The environment is in bad shape. Three of the nine 'planetary boundaries' have been exceeded. Climate change seems unstoppable, the level of nitrogen emission is way too high and there is so much biodiversity loss that some are talking of the sixth mass extinction. How did we get to this point? What are the root causes? And what do we have to do to turn the tide? Environmental scientist Prof Sarah Cornell (Stockholm Resilience Centre) and sustainability consultant Gerard Roemers (Metabolic) investigate our planetary boundaries.