Risk

Beneath one of Italy's most densely populated cities, there is danger brewing.

Pre-modern states and civilisations became more prone to collapse as time passed – a pattern that holds lessons for today's ageing global powers.

Certain personality traits can predispose people to taking more risks on the road – but societal biases also lead to recklessness behind the wheel.

Before he wrote The Lord of the Rings, the author JRR Tolkien coined a word – "eucatastrophe". What did he mean, and why could it relate to humanity's future?

There are a handful of actors who are the most likely to cause a global catastrophe, but their power goes unchecked, says Luke Kemp.

In recent history, a few individuals have made decisions that could, in theory, have unleashed killer aliens or set Earth's atmosphere on fire.

Nerve agents like novichok, sarin and VX can produce symptoms similar to a heavy cold at first, but they kill in minutes and spread fear almost as toxic as the substances themselves.

If you weigh up the long-term impact of catastrophes on future generations, it is hard not to see their prevention as one of our greatest priorities, argues Seth Baum.