At the start of every year, the Bulletin of Atomic Scientists announces the "time." The clock stands as reminder of how close the planet is to midnight, a symbol for catastrophe or the end of times. This year, the clock edged closer than it has ever been since the Cold War: it's now only two-and-a-half minutes from midnight, according to a report from The Atlantic.

The history of the clock

Vox put together a video that explained the development of the Doomsday Clock.

Martyl Langsdorf designed the Doomsday Clock for the cover of the Bulletin of the Atomic Scientists magazine, but it quickly popularized and became a worldwide symbol for the deadly and very real threat of nuclear apocalypse.

Although the threat of atomic bombs have ceased, the Bulletin continues to update the Doomsday Clock annually. Existential threats are now taken in consideration, different catastrophes that threaten to devastate or wipe out humanity.

Many acclaimed scientists like Stephen Hawking, Susan Solomon, Lisa Randall, and Freeman Dyson are involved with the Bulletin.

Two and a half minutes until midnight

"This is the closest to midnight the Doomsday Clock has ever been in the lifetime of almost everyone in this room," Lawrence Krauss, a theoretical physicist at Arizona State University and the chair of the Bulletin's board of sponsors, told The Atlantic. "It's been 64 years since it was closer."

The only time it was closer was two minutes before midnight back in 1953, after both the United States and the Soviet Union tested hydrogen bombs. It remained stuck at that time for seven years.

At a press conference earlier this year, the scientists making up the Bulletin revealed that their concern for the words of Donald Trump and Vladimir Putin affected the movement of the clock.

"Nuclear rhetoric is now loose and destabilizing," Thomas Pickering, American diplomat who served under George H.W. Bush and Bill Clinton's administrations, explained. "We are more than ever impressed that words matter, words count.

However, chief of all threats in modern society is climate change, which scientists stressed should be addressed directly by administrations. Other existential risks that were taken into account in this year's time included cyber warfare, biological weapons with the rise of gene-editing technology, and even the dangers of fake news.