The Doomsday Clock is an imperfect metaphor — but the existential danger is all too real

Every year, the Bulletin of the Atomic Scientists convenes a meeting to decide whether the minute hand of its famous Doomsday Clock will move forward, backward or stay put. Invented in 1947, the clock is a metaphor aimed at conveying our collective proximity to global destruction, which is represented by midnight: doom. Initially set to seven minutes before midnight, the minute hand has wiggled back and forth over the decades: In 1953, the year after the U.S. and Soviet Union detonated the first thermonuclear weapons, it inched forward to a mere two minutes before doom, where it stayed until 1960, when it returned to the original setting. In 1991, following the dissolution of the Soviet Union, which marked an official end to the Cold War, the minute hand was pushed back to a reassuring 17 minutes.

Since then, however, the time has pretty steadily lurched forward, and in 2018 the Bulletin's Science and Security Board once again placed the time at two minutes before midnight, due to growing nuclear tensions and the ignominious failure of world governments to properly address the worsening climate crisis. Two years later, the minute hand moved forward to just 100 seconds before midnight, and this January — the most recent Doomsday Clock announcement — it was, for the first time ever, inched forward to 90 seconds.

But what exactly does this mean? The Doomsday Clock has plenty of critics, and my sense is that even those who like the metaphor agree that it's not perfect. The minute hands of most clocks don't move backward, and the Doomsday Clock, once its minute hand is set, doesn't start ticking forward. Many people on social media dismiss it as "scare-mongering," a way of frightening the public — which is not entirely wrong, as the Bulletin's purpose from the start was, to quote one of its founders, Eugene Rabinowitch, "to preserve civilization by scaring men into rationality." There is, in fact, a long tradition since the Atomic Age began in 1945 of employing what historian Paul Boyer describes as "the strategy of manipulating fear to build support for political resolution of the atomic menace."

One sees this very same strategy being employed today by environmentalists like Greta Thunberg, who declared before an audience at Davos in 2019: "I don't want your hope. I don't want you to be hopeful. I want you to panic. I want you to feel the fear I feel every day. And then I want you to act." Fear can be paralyzing, but it can also be a great motivator. They key is to figure out how to inspire what the German philosopher Günther Anders described as "a special kind" of fear, one that "drive[s] us into the streets instead of under cover." It's hard to know whether the Doomsday Clock does this. It certainly hasn't inspired large protests or demonstrations, although it is taken seriously by some political leaders, and in fact the Kremlin itself reacted with alarm to the announcement, blaming — of course — the U.S. and NATO.

Aside from potential problems with the metaphor and questions about the efficacy of fear, the Doomsday Clock does convey something important: Humanity is in a genuinely unprecedented situation these days, in the mid-morning of the 21st century. The fact is that before the invention of thermonuclear weapons in the early 1950s, there was no plausible way for humanity — much less a handful of individuals with twitching fingers next to some "launch" button — to completely destroy itself. Perhaps everyone around the world could have decided to stop having children, a possibility considered in 1874 by the English philosopher Henry Sidgwick (who said it would be "the greatest of conceivable crimes"). Some people around that time argued that we should do exactly that, arguing that life is so full of suffering that it would be better if our species were extinguished. Consider German philosopher Philipp Mainländer, who after receiving the first copies of his magnum opus on pessimism in 1876, stacked them up on the floor, climbed to the top of the pile and hanged himself.

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Yet even Mainländer acknowledged that persuading everyone to stop their baby-making activities (he advocated for celibacy) would be difficult. Human extinction by choosing not to procreate just isn't realistic. But thermonuclear weapons really could create an anthropogenic extinction scenario. How? The main danger, you may be surprised to learn, isn't from the initial blasts. Those would certainly be catastrophic, and indeed the most powerful thermonuclear weapon ever detonated — the Soviet-made Tsar Bomba, tested just once in 1961 — had an explosive yield more than 1,500 times that of the bomb dropped on Hiroshima, which destroyed much of the city. That's bigger than most of the weapons in our nuclear arsenal, but these can still wreak horrific havoc, as you can see for yourself by testing out different weapons in different cities on Nuke Map.

But in fact, the greater threat comes from the possibility that nuclear explosions would ignite massive conflagrations called firestorms, so hot that they produce their own gale-force winds. The explosion over Hiroshima, in fact, triggered a hellish firestorm that, along with the initial blast, killed roughly 30 percent of the city's population.The intense heat would catapult large quantities of the black soot produced by these fires straight through the troposphere — the layer of the atmosphere closest to Earth's surface — and into the stratosphere, the next layer up, which you may have traversed if you've ever flown in a commercial jetliner over the poles.

This is an important point, because there are several ways that soot could be removed from the atmosphere. The first is weather: You could think of rain as a kind of atmospheric sandpaper, removing aerosols floating about the air. The second is gravity: if some particulate matter is heavier than the air, it will eventually fall back to Earth. But first of all, there's no weather in the stratosphere, so this mechanism of removing soot won't work. And second, gravity takes a pretty long time to remove stuff like soot, which means once the soot is in the stratosphere, it's going to stay there for a while — potentially years.

That soot would blocks incoming light from our life-giving sun. Without light, photosynthesis can't happen, and without photosynthesis, plants die. Without plants, global agriculture and food chains would collapse, and the surface of our planet would plunge into subfreezing temperatures. So even someone thousands of miles away from any possible ground zero — that is, where the thermonuclear blasts occur — would sooner or later starve to death under pitch-black skies at noon. According to a 2020 study, a nuclear war between India and Pakistan could kill more than 2 billion people, while a war between the U.S. and Russia could result in 5 billion deaths, more than 60% of the entire human population. An all-out nuclear war involving every nuclear power in the world today? Carl Sagan himself wrote in 1983 that "there seems to be a real possibility of the extinction of the human species," although not everyone would agree with this assessment.

So when people complain that the Doomsday Clock announcement is nothing but scare-mongering, spreading alarm for no good reason, they're just plain wrong. The nuclear threat is real, which is why all the nuclear saber-rattling that Vladimir Putin engaged in leading up to the Ukraine war literally kept me up at night. In fact, what caused those sleepless nights wasn't just the thought of Putin detonating a "tactical" nuclear device in Ukraine, although that could easily create a situation that quickly spirals out of control, creating a nuclear nightmare affecting billions.

I was also nervous about the possibility of a miscalculation, error, or accident that could trigger Armageddon. The history of nuclear near-misses is frankly shocking. My advice is not to fall down this particular rabbit-hole before bed. Did you know, for example, that an undetonated nuclear bomb is buried somewhere in the farmland around Goldsboro, North Carolina? It accidentally fell out of an airplane, and was never recovered. Consider the case of Vasili Arkhipov, who was a naval officer on a Soviet submarine during the Cuban missile crisis of 1962. After losing contact with Moscow, the submarine's captain believed that war might have already broken out, and wanted to launch a nuclear torpedo at the U.S. But all three senior officers had to agree to such a launch, and Arkhipov stubbornly resisted. He may well have single-handedly saved the world, quite a legacy to leave behind.

Considering that history, I've wondered how many near-misses there may have been during the Ukraine war, especially since Putin put his nuclear forces on "high alert," that we won't learn about for many years (if we ever do). How close have we come to the brink without realizing it? It remains entirely possible that a mistake, tomorrow or next week or next month, could start World War III.

This is the world we now live in, and it's why the warnings behind the Doomsday Clock are nothing to sneeze at. And we haven't even gotten to climate change, the other major threat that the Bulletin considers when setting the clock's time. Although it's fair to say that climate change is unlikely to cause our complete extinction, the potential harm it could cause will be unprecedented in human history. The future world your grandchildren will live in will be profoundly different, and in many ways worse, than the one we now occupy. If civilization is an experiment, it's failing. The only other single species to alter the biosphere as much as we have, and as we will in the coming centuries, was a single-celled critter called cyanobacteria, which some 2.5 billion years ago flooded the atmosphere with oxygen for the first time. Since oxygen is toxic to anaerobic organisms, that may have initiated a mass extinction event, although it's hard to know for sure because there aren't many fossil remains from that period of Earth's history.

The point is that climate change also poses real, urgent and profound dangers. It will negatively impact the livability of our planet for the next 10,000 years, a significantly longer period than what we call "civilization" has existed. So this is no joke. The Doomsday Clock, for all its flaws, should be taken seriously by every citizen of our planet. Right now, it stands at 90 seconds to midnight, and given that climate change is worsening and there's no end in sight to the war in Ukraine, we can expect the clock's minute hand to keep moving forward.