At a conference in Mexico, one scientist’s outburst launches a global quest.

Hannah Fry follows a group of researchers on the hunt for a ‘golden spike’: the boundary, marking a shift into a dramatic new geological period dominated, not by volcanoes and asteroids, but the influence of humans.

From plastics and concrete to nuclear fallout, the data they uncover reveals a planet profoundly changed. But can these scientists persuade their colleagues - and the world?

Producer: Ilan Goodman