This week Oxford academic and 80,000 Hours trustee Dr Toby Ord released his new book The Precipice: Existential Risk and the Future of Humanity. It's about how our long-term future could be better than almost anyone believes, but also how humanity's recklessness is putting that future at grave risk — in Toby's reckoning, a 1 in 6 chance of being extinguished this century.

I loved the book and learned a great deal from it (buy it here, US and audiobook release March 24). While preparing for this interview I copied out 87 facts that were surprising, shocking or important. Here's a sample of 16:

1. The probability of a supervolcano causing a civilisation-threatening catastrophe in the next century is estimated to be 100x that of asteroids and comets combined.

2. The Biological Weapons Convention — a global agreement to protect humanity — has just four employees, and a smaller budget than an average McDonald’s.

3. In 2008 a 'gamma ray burst' reached Earth from another galaxy, 10 billion light years away. It was still bright enough to be visible to the naked eye. We aren't sure what generates gamma ray bursts but one cause may be two neutron stars colliding.

4. Before detonating the first nuclear weapon, scientists in the Manhattan Project feared that the high temperatures in the core, unprecedented for Earth, might be able to ignite the hydrogen in water. This would set off a self-sustaining reaction that would burn off the Earth’s oceans, killing all life above ground. They thought this was unlikely, but many atomic scientists feared their calculations could be missing something. As far as we know, the US President was never informed of this possibility, but similar risks were one reason Hitler stopped…

N.B. I've had to cut off this list as we only get 4,000 characters in these show notes, so:

Click here to read the whole list, see a full transcript, and find related links.

And if you like the list, you can get a free copy of the introduction and first chapter by joining our mailing list.

While I've been studying these topics for years and known Toby for the last eight, a remarkable amount of what's in The Precipice was new to me.

Of course the book isn't a series of isolated amusing facts, but rather a systematic review of the many ways humanity's future could go better or worse, how we might know about them, and what might be done to improve the odds.

And that's how we approach this conversation, first talking about each of the main threats, then how we can learn about things that have never happened before, then finishing with what a great future for humanity might look like and how it might be achieved.

Toby is a famously good explainer of complex issues — a bit of a modern Carl Sagan character — so as expected this was a great interview, and one which Arden Koehler and I barely even had to work for.

Some topics Arden and I ask about include:

• What Toby changed his mind about while writing the book

• Are people exaggerating when they say that climate change could actually end civilization?

• What can we learn from historical pandemics?

• Toby’s estimate of unaligned AI causing human extinction in the next century

• Is this century the most important time in human history, or is that a narcissistic delusion?

• Competing vision for humanity's ideal future

• And more.

Get this episode by subscribing: type '80,000 Hours' into your podcasting app. Or read the linked transcript.

Producer: Keiran Harris.