Each year, the Bulletin of the Atomic Scientists updates its Doomsday Clock – a measurement of the threat posed by nuclear weapons, climate change and other existential threats to humanity. And the news this year was not good. Kennette Benedict, former executive director and publisher of the Bulletin, joins us to talk about why last year we ticked forward another 30 seconds closer to the end of the world – and about if there’s anything we can do to turn back the clock.