Are we now entering a mass extinction event? What can mass extinctions in Earth's history tell us about the Anthropocene? What do mass extinction events look like and how does life on Earth recover from them? The fossil record reveals periods when biodiversity exploded, and short intervals when much of life was wiped out in mass extinction events. In comparison with these ancient events, today's biotic crisis hasn't (yet) reached the level of extinction to be called a mass extinction. But we are certainly in crisis, and current parallels with ancient mass extinction events are profound and deeply worrying. Humanity's actions are applying the same sorts of pressures - on similar scales - that in the past pushed the Earth system out of equilibrium and triggered mass extinction events. Analysis of the fossil record suggests that we still have some time to avert this disaster: but we must act now.