How to read the Doomsday Clock (2024)

The Doomsday Clock depicts how close humanity is to armageddon – but where did it come from, how do you read its time, and what can we learn from it? Existential risk researcher SJ Beard explains.

I first became aware of the Doomsday Clock at school in the mid-1990s when a teacher introduced it to me. She told my class about the grand sweep of history, explaining that if everything that had happened on our planet was compressed into a single year, then life would have emerged in early March, multi-cellular organisms in November, dinosaurs in late-December – and humans wouldn't arrive on the scene until 23:30 on New Year’s Eve. Then she contrasted this great swathe of history with how short our futures might be, and told us how a group of scientists in the US thought we may only have a few metaphorical minutes left until midnight.

It's a powerful story, and for many years I thought this is what the Doomsday Clock meant: that its hands represented the time we have left before the end. However, that's not quite accurate.

Every year, the scientists responsible for the Doomsday Clock at the Bulletin of the Atomic Scientists publish their annual judgement of how close its hands sit to midnight. In January 2024, they did it for the 76th time. On each occasion, the announcement highlights the complex web of catastrophic risks facing humanity, including weapons of mass destruction, environmental breakdown and disruptive technologies. In 2020, the Bulletin's president, Rachel Bronson, solemnly announced that its hands had moved closer to armageddon than ever before – only 100 seconds. It remained at that position in 2021 and 2022 only to move 10 seconds closer in 2023, where it stayed in 2024. But to understand what that really means, you need to understand the story of the Clock, where it came from, how to read it, and what it tells us about humanity's existential predicament.

Setting the Clock in motion

The speed and violence with which nuclear technology evolved was breathtaking, even to those closely involved in its development. In 1939, world-renowned scientists Albert Einstein and Leo Szilard wrote to the US president about a breakthrough in nuclear technology that was so powerful, and could have such tremendous battlefield consequences, that a single nuclear bomb, "carried by boat and exploded in a port, might very well destroy the whole port". It was a possibility too significant to ignore. This letter led to the establishment of an enormous scientific, military, and industrial collaboration, the Manhattan Project, that a mere six years later produced a bomb much more powerful than the one imagined by Einstein and Szilard, capable of destroying an entire city and its population. Only a few years after that, nuclear arsenals were capable of destroying civilisation as we know it.

The first scientific concern that nuclear weapons might have the potential to end humanity came from the scientists involved in the first nuclear tests. They were concerned that their new weapons might accidentallyignite the Earth's atmosphere. These worries were quickly dismissed and, thankfully for all concerned, proved false.

Still, many who worked on the Manhattan Project continued to have strong reservations about the power of the weapons they helped to produce. After the first successful controlled nuclear chain reaction at the University of Chicago in 1942, the team of scientists working on the Manhattan Project dispersed, with many moving to Los Alamos and other government laboratories to develop nuclear weapons. Others stayed in Chicago undertaking their own research, many of whom were themselves immigrants to the US and keenly aware of the intertwining of science and politics. They began actively organising in an attempt to keep the future of nuclear technology safe. For instance, they helped advancethe Franck Reportin June 1945, which foresaw a dangerous and costly nuclear arms race, and argued against a surprise nuclear attack on Japan. Of course, its recommendations were not accepted by decision makers at the time.

This group went on to establish the Bulletin of the Atomic Scientists of Chicago (the Bulletin), whose first issue was published a mere four months after the atomic bombs were dropped on Hiroshima and Nagasaki. With support from the University of Chicago president, and engaging with colleagues in international law, political science, and other related fields, they helped kick off and support a global citizen-scientist movement able to affect the global nuclear order. For instance, it proved remarkably successful at establishing a "nuclear taboo" – in private conversations, the US Secretary of State complained that the "stigma of immorality" prevented the US from using nuclear weapons.

In choosing to remain based in Chicago, the founders signalled their intention to focus on engaging with their fellow scientists and members of the public about the political and ethical challenges of nuclear technology, rather than focusing on the political and military leaders who had been so dismissive of their concerns thus far. They argued that public pressure was key to political responsibility, and education was the best channel to ensure it.

Two years after its founding, the Bulletin chose to switch from a printed newsletter to a magazine format in order to engage a wider readership. It was at this point that they engaged landscape artist Martyl Langsdorf to design a symbol for their new cover, for which she produced the first Doomsday Clock. Married to a Manhattan Project scientist, Langsdorf understood the urgency and desperation her husband and colleagues felt about managing nuclear technology. She created the Clock to draw attention both to the urgency of the threat they faced and also her belief that responsible citizens could prevent catastrophe by mobilising and engaging – the message of the Clock was that its hands might tick forwards or be set backwards.

In 1949, the USSR tested its first nuclear weapons, and in reaction to this the Bulletin’s editor moved the hands of the Clock from seven to three minutes to midnight. In doing so, he activated the Clock, turning it from a static to a dynamic metaphor. The Clock would evolve into a symbol that, according to Kennette Benedict, former executive director of the Bulletin, is a warning to "the public about how close we are to destroying our world with dangerous technologies of our own making. It is a metaphor, a reminder of the perils we must address if we are to survive on the planet".

In 1953, the Clock moved forward yet again, to two minutes to midnight, after the US and Soviet Union detonated the first thermonuclear weapons. This was the closest to midnight the Clock was ever set in the 20th Century.

Reading the Clock

But what do these times and movements really mean? While it’s easy to interpret the Doomsday Clock in the way my schoolteacher did, as a prediction of the time humanity has left, that would be very hard to predict and is of little use if your intention is to prevent doomsday rather than merely predicting it.

A more plausible reading is that the Clock is meant to indicate the current level of risk facing humanity, and some have indeed tried to assess this. In 2003, Martin Rees, the cosmologist and UK Astronomer Royal, argued that "I think the odds are no better than 50:50 that our present civilisation on Earth will survive to the end of the present century". Nor is he alone, a database of such risk assessments collated by a researcher at the University of Oxford currently contains over 100 predictions by various scientists and philosophers who study the matter. However, useful as these estimates might be they are intended as long-range assessments, not real-time snapshots of the current level of risk.

Instead, dedicated clock watchers like myself interpret the movement of the Doomsday Clock rather differently. Its goal is not to tell us how big the risk facing humanity is, but how well we are doing at responding to that risk. For instance, in 1962 the Cuban Missile crisis is generally agreed to have been the closest the world ever came to nuclear war, but its occurrence did not move the Clock at all. On the other hand, the 1963 Partial Nuclear Test Ban Treaty saw the Clock's hands shifted back from midnight an entire five minutes.

And this makes sense, at least to researchers of existential risk such as myself. Friends often turn to me for information during times of increased global political attention, such as the 2017 diplomatic crisis between the US and North Korea or the collapse of the Iran nuclear deal in 2018. However, I generally have to disappoint them. Events like this simply are not what we spend most of our time studying or worrying about. In fact, they are perfectly normal fluctuations in international politics and diplomacy. What worries people like me is firstly the existence of weapons that leaders could draw on in such a crisis and secondly the inadequate and sometimes dysfunctional institutions and frameworks to stop them doing so. These problems are not created by individual global crises, they are systemic in nature and this is what the Doomsday Clock is trying to measure.

Though I wasn’t fully aware of it at the time, the point at which I first became concerned about the Doomsday Clock in the mid-1990s coincided with the moment of greatest safety humanity has experienced since World War Two. Between 1987 and 1991, the Clock reversed an astonishing 14 minutes in four years, as declining Cold War tensions allowed the great powers to conclude a series of international measures that provided significant protection against the threat of nuclear war. Most notable amongst these were the 1987 Intermediate-Range Nuclear Forces Treaty, which banned all Russian and US land based ballistic missiles with ranges between 500 and 5,500km (312 to 3,416 miles) and saw 2,692 nuclear missiles removed from service, and the 1991 Strategic Arms Reduction Treaty (Start), which would eventually lead to the removal of around 80% of nuclear weapons.

In 2007, the Bulletin formally began to consider climate change alongside nuclear threats in setting the Clock. Of course, these risks are quite different: a nuclear exchange could happen within minutes while climate risk is accumulating year after year. Similarly, responsibility for the world’s nuclear weapons lies in the hands, or at the fingers, of a very few global decision makers, while we are all engaged in climate change and environmental destruction, even if to a very unequal extent. However, the severity of these two risks, both in terms of their potential to cause global catastrophes and their likelihood of doing so, are undoubtedly comparable. For both risks, we need to consider whether or not the current level of global action being taken to combat them is proportional to this severity and the rising urgency of reducing it.

For many years, the pages of the Bulletin have also considered the challenges posed by new disruptive technologies and these now also influence the hands of the Doomsday Clock. These include artificial intelligence, biological weapons, and nanotechnology. As well as specific technologies, our future is also increasingly imperilled by the convergence of disruptive technologies with existing nuclear and environmental threats.

A second factor for the closer position to midnight is that, as the number and variety of threats facing humanity has multiplied, so have the seriousness of the challenges in governing these risks. In 2015, the Bulletin moved its Doomsday Clock from five to three minutes to midnight, noting three key issues behind this move. Firstly, deteriorating relations between the US and Russia, who together possess 90% of the world’s nuclear arsenal, and the undermining of many of the instruments designed to keep those arsenals safe, such as the successor to the Start treaty (New Start). Secondly, every nuclear weapon state was investing massively in its nuclear weapons systems, including replacement, expansion, and modernisation. Finally, the global architecture needed to address climate threats was nowhere in sight.

In 2016, however, it identified two possible bright spots, with the potential to reverse some of these negative trends: the Iran nuclear deal and the Paris climate agreement. However, it also noted that neither had been fully implemented. In 2017, they were forced to conclude that the situation had significantly worsened, with both of these bright spots being dimmed by changes in US domestic politics. This was coupled with growing evidence of a global disparagement of expertise and a recklessness about nuclear language and leadership. They thus moved the Clock to two-and-half minutes to midnight, and in 2018 moved it to two minutes due to the continuing deterioration of international diplomacy.

The time since 2023 – 90 seconds to midnight – has reflected the sheer instability of the global situation, and the failure of international institutions to respond to the ticking clock of existential risk. This included the collapse of the Intermediate Nuclear Forces Treaty that had marked the beginning of the end of the Cold War. While there may no longer be any clear ideological struggle driving international conflict, the scale of disagreement between the great powers and the lack of institutions for resolving these disagreements, both seem to be as bad as they ever were, and yet the ways in which such disagreements could lead to a global catastrophe continue to multiply.

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Even if the Doomsday Clock moves no closer to midnight in the next update, we should not be complacent. Covid-19 could have been a crisis that pulled governments together to make all of us safer, as the Cuban Missile Crisis did 60 years ago, but it was not. It's hard to see how things could improve significantly without yet more crises and disasters to finally spur us into action. However, what we learn from the Doomsday Clock is that our ability to deal with such crises is likely worse than it ever has been. The Clock is still ticking, and if we cannot turn back its hands then the chimes of midnight may not be far away.

* SJ Beard is a researcher at the Centre for the Study of Existential Risk at the University of Cambridge. They tweet@CSERSJ.

This article was originally published on 20 January 2022, but was updated on 23 January 2023, and again on 23 January 2024.

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