The Bulletin of the Atomic Scientists has now adjusted the minute hand on their famous Doomsday Clock. This is significant because the clock, first created in 1947 to "convey how close humanity is to catastrophic destruction," has only been previously adjusted 19 times across six decades.
As a symbol, I have nothing against the Doomsday Clock. In our individual lives it’s always a good thing to remember we’re all mortal—that one day we will die, meaning we’d better live the best life we can in the time we have left. The same sentiment applies to the fate of our species. It’s a goodness to remember that, despite what the human ego may scream at us, our species has only existed on this planet for a short time and could easily go the way of the dinosaurs (those that weren't the ancestors of birds, that is).
However, as an accurate predictor of how close humanity is to destruction the Doomday CLock leaves much to be desired. For example, the above image from Wikipedia shows how close humanity was to destruction during the clock’s 65 year history. The closest we’ve supposedly come to killing ourselves off was in 1953, when we were at “2 minutes to midnight” after the United States tested the first thermonuclear device, followed nine months later by a similar H-bomb test by the Soviet Union. But while the Doomsday Clock in 1953 warned of our imminent destruction, a study of history shows humanity was actually further away from killing itself than the clock suggested.
Yes, the risk of a nuclear war existed during that time period. But the stockpiles of weapons controlled by the U.S. and Soviet Union in 1953 were not yet sufficient to destroy humanity. That wasn’t, however, the case in 1962, when the Cuban Missile Crisis occurred. In recent years it has been revealed that this incident came extremely close to triggering a nuclear war at a time when there were indeed enough weapons to destroy the world.
But despite this, the Doomsday Clock in 1962 was relatively far removed from doomsday and was about to climb to the "safest" position it has been at any time except for immediately after the end of the Cold War. What I believe this shows is that it’s not true scientific analysis which drives the Doomsday Clock—it is the political perception of the involved scientists. The explosion of the first H-bomb was a startling event for the human psyche. For the first time, we had the ability to create weapons which could—if produced in sufficient numbers—destroy the world. It didn’t matter that there were not yet enough of these weapons to actually do this deed. All that mattered was perception.
The same thing happened in the late 1980s, when numerous arms control treaties were passed and the Cold War ended. The Doomsday Clock was literally behind the times and had to be continually reset to reflect this new reality.
So while the Doomsday Clock is a great propaganda tool for reminding humanity of the harm we could do to ourselves, as a predictor of the actually risks of an apocalypse the clock is as flawed as any other human artifact.