The Doomsday Clock, which has been used to examine the world’s vulnerability to global catastrophe for nearly a century, has moved one second closer to midnight. On Jan. 28, the Bulletin of the Atomic Scientists announced that the Doomsday Clock was set at 89 seconds to midnight,

Atomic scientists on Tuesday moved their "Doomsday Clock" closer to midnight than ever before, citing Russian nuclear threats amid its invasion of Ukraine, tensions in other world hot spots, military applications of artificial intelligence and climate change as factors underlying the risks of global catastrophe.

The Doomsday Clock now stands at 89 seconds to midnight, the closest to catastrophe in its nearly eight-decade history. Here's a look at how — and why — it's moved.