(CNN) The Doomsday Clock was reset Thursday to just 100 seconds before midnight -- the closest we have ever been to the complete and total annihilation of the earth (well, at least metaphorically).
Midnight on the Clock symbolizes the end of the world, and each year, the Bulletin of the Atomic Scientists decides what time it is.
"It is 100 seconds to midnight. We are now expressing how close the world is to catastrophe in seconds -- not hours, or even minutes," the Bulletin's President Rachel Bronson said in a statement. "We now face a true emergency -- an absolutely unacceptable state of world affairs that has eliminated any margin for error or further delay."
So what factors determine how close we are to midnight? Mainly, the threat of nuclear weapons and climate change, Bronson said.
When the Clock was created in 1947, the greatest threat to humanity was nuclear war as the US and Soviet Union were headed into a nuclear arms race.
"But in 2007, we felt we couldn't answer those questions without including climate change," Bronson told CNN.
In recent years, the Bulletin's panel of scientists and other experts has started to look at other "disruptive technologies," including artificial intelligence, gene editing, and cyber threats, Bronson said.
While climate change and the nuclear threat remain the main factors, the Bulletin has identified "cyber intrusions and fake news as a threat enabler," Bronson said. "The information environment has become complicated and increasingly difficult to separate out facts from fiction, and that has made all the other threats more significant."
The threats of nuclear destruction and global warming might seem too big for us to handle, but the Bulletin's goal is not to use the Clock as a scare tactic, but to get people talking.
"What we try to do is give the public the ability to talk about the state of nuclear security and to really pressure their leaders to pay attention to that and climate change and show that they're concerned about it," Bronson said.
"In democracies, we try to encourage people to talk to their political representatives that these huge investments that are going into nuclear arsenals might be directed elsewhere. That arms control agreements should be signed to reduce the threats."
In fact, the Clock hand has been moved away from midnight almost as often as it was moved closer, the Bulletin said.
It moved the hand farthest away -- a whopping 17 minutes before midnight -- in 1991, when President George H.W. Bush's administration signed the Strategic Arms Reduction Treaty with the Soviet Union.