Mark Lynas is an author, campaigner, and speaker. He is science advisor with the the Climate Vulnerable Forum, an alliance of 74 developing countries and small island states. He is also policy lead with WePlanet, a pro-science environmental advocacy network active in over 20 countries. He has co-authored peer-reviewed papers on vaccines, climate and GMOs, written for the Guardian, New York Times, and Washington Post among many other media outlets; and appeared in the films Pandora’s Promise, The Age of Stupid, and The Island President. His climate book Six Degrees won the Royal Society science books prize in 2008 and was translated into 22 languages. He is based in the UK on the Welsh borders, where he volunteers locally to support rewilding.
What’s the big idea?
It’s tough to imagine and unpleasant to even consider, but ignoring the catastrophic risk of nuclear war is no solution. We live with nukes all around the globe that are a hair-trigger away from detonation during a time of severe geopolitical instability. There is no winning a war like this, and the only way to make sure our worst nightmares become impossibilities is to attain global zero: no nuclear weapons whatsoever.
Below, Mark shares five key insights from his new book, Six Minutes to Winter: Nuclear War and How to Avoid It. Listen to the audio version—read by Mark himself—in the Next Big Idea App.
1. We are living at a particularly dangerous time.
Nuclear war is a real possibility due to the geopolitical instability of our times. We are now as close to the brink as at any stage since, perhaps, the Cuban Missile Crisis in 1962. The risk of nuclear war fluctuates but has been calculated at 1 percent per year, given near misses and ongoing superpower brinkmanship. One percent may not sound like a lot, but it adds up to a cumulative probability of approximately two-thirds over a century. Given that nuclear weapons were invented and first used in 1945, our children therefore might have a less than 50/50 chance of living to 2045 without a nuclear Armageddon.
Virtually all the old arms control treaties dating from the Cold War have collapsed. The final one, the New START treaty, will expire next February. Meanwhile, China is aiming for nuclear parity with the U.S. and Russia. They have about 500 warheads now and are planning for 1,000 by 2030. Hardened missile silos are appearing across the deserts of northern China. Iran is probably going to get a bomb within months—or weeks if the U.S. and Israel attack their nuclear sites. Russia showed clearly in Ukraine that nuclear weapons are still useful for wars of aggressive conquest, even if you don’t actually use them, because their deterrent effect reduces pushback from the rest of the world. India and Pakistan are again close to war over Kashmir, and both have nuclear weapons collectively numbering in the hundreds.
The most crazily dangerous aspect of all this is that we have thousands of nuclear weapons on hair-trigger alert. In the U.S., the President has sole launch authority, which means that he does not need to consult anyone, and no one in the chain of command has the authority to refuse a direct presidential launch order. He only has an estimated six-minute decision window to decide whether to launch a retaliation if an enemy attack is detected. This means six minutes to decide whether to unleash a nuclear war that will destroy the human race and much of the biosphere. This hugely raises the possibility of a catastrophic error, and indeed, such near-misses have happened several times over the decades due to faulty software, personal misinterpretations, and computer glitches.
“This means six minutes to decide whether to unleash a nuclear war that will destroy the human race and much of the biosphere.”
Perhaps the scariest near-miss was during the Cuban Missile Crisis itself, on Black Saturday, October 27, 1962. The American Navy forced a Soviet submarine to surface near the exclusion zone President Kennedy had declared around Cuba. The Americans didn’t know that this sub had a nuclear-tipped torpedo, and when they harassed it with depth charges and machine gun fire, the Soviet captain decided to dive and launch the device—which would have initiated nuclear war. Fortunately, the signaller became stuck in the conning tower, and a superior officer who was also on board was delayed long enough to see that the Americans were signalling an apology. They called off the launch. That was a close call.
2. Nuclear war would be almost unthinkably bad.
Imagine a zombie apocalypse, but worldwide and for real. In a nuclear exchange between America and Russia, most of the cities in the northern hemisphere would be burned, and an estimated 700 million people would die in the initial blasts and firestorms. These are people who are mostly burned alive or vaporized on the spot, if they are lucky. It includes another few tens of millions who die from fatal radiation poisoning in the next few days and weeks. Their hair falls out, and their gut lining shears off, leading to septicemia and multiple organ failure.
But that’s just the beginning. What happens next is far worse. Nuclear winter was a concept first proposed in the 1980s, when scientists realized that soot particles from burning cities would end up in the stratosphere, above the weather-generating layer of the atmosphere, and therefore would block out the sun for years. Recent climate models have shown that nuclear winter is a reality, and that food production would shut down overnight as a period of near-total darkness led to ice age temperatures for the best part of a decade. Photosynthesis would stop, and our breadbasket food-producing areas would freeze solid. This would cause a nuclear famine, and whole populations of the combatant nations would starve.
That’s what I mean when I talk about a zombie apocalypse. Picture the scene of literally billions of shell-shocked survivors, roaming the land in search of food as they gradually starve to death. It’s worse than a horror movie, because this could really happen to all of us, and our families and kids, unless we do something quickly to de-escalate the current nuclear confrontation. I’m asking you to imagine it because it’s the only way to ensure that it never happens.
“It’s worse than a horror movie, because this could really happen to all of us.”
Perhaps the closest analogue for the effects of a full-scale nuclear war is the asteroid that destroyed the dinosaurs and caused a mass extinction at the end of the Cretaceous Period, 66 million years ago. That also caused a worldwide firestorm that deposited so much soot in the atmosphere that it became completely dark at the surface and led to freezing temperatures across the entire globe. There was nothing the dinosaurs could have done to prevent this, but we have a NASA-led program to detect and (if necessary) deflect planet-threatening asteroids. But how clever are we really if we build and design our asteroids and point them directly at our cities in the form of intercontinental ballistic missiles tipped with thermonuclear warheads?
3. Nuclear war is a more catastrophic immediate risk than climate change.
Climate warming is a cumulative problem that will harm the planet over decades as ice caps melt, heatwaves intensify, and food production is harmed. But there is still time to adapt to many of the impacts and lessen their intensity. In comparison, nuclear war can destroy the biosphere and human civilization in a matter of hours, and there are no conceivable adaptations or even survival options for most of the human population.
This makes nuclear war by far our worst and most urgent existential risk. It’s worse than pandemics, which we can hope to control with mitigation measures and vaccines. It’s worse than any negative realistic outcome with AI—the worst thing that anyone can imagine (as was the fictional scenario in the Terminator films) is AI taking control of nuclear weapons and using them to exterminate most of humanity. In which case, we’re back to the real threat of nuclear weapons themselves.
4. Any nuclear war is unlikely to be a limited affair.
If you destroy New York or Shanghai, do you think there would be no retaliation? You always have to punish an aggressor. Our whole moral code depends on it. So, you wipe out two cities, and the national capital for good measure. Then the wounded enemy responds with their full force. The entire process would likely unfold in under an hour, far too quickly for anyone to fully comprehend what is happening.
We have to reduce the current risk of catastrophic miscalculation by taking all nuclear weapons off hair-trigger alert. It doesn’t make sense to ask the U.S. president, or anyone, to decide whether or not to end civilization in a six-minute window. Of course, there is no scenario where the use of nuclear weapons makes sense, which is why we need to get rid of them. Make no mistake: humanity will not survive long term unless we abolish nuclear weapons. It’s either us or them.
“We have to reduce the current risk of catastrophic miscalculation by taking all nuclear weapons off hair-trigger alert.”
All of this is why global zero is the only option. If any country has a nuclear weapon, you need a nuclear weapon too for deterrence. This develops into an arms race, and sooner or later, the human race destroys itself. The only way out of this collective action dilemma is for nobody to have a nuclear weapon. Not one.
5. A lot of people say nuclear war will never happen.
If you do, then you’re rolling the dice with a two-thirds risk of ending the world. I recall a time when it was declared impossible that we would ever take climate change seriously. When I began my first climate book back in 2000, there were no electric cars, solar power was incredibly expensive, wind was a joke, and grid-scale batteries didn’t exist. We now have serious climate targets for most of the world’s big economies, and most experts believe the clean energy transition is already unstoppable. Nuclear weapons involve just nine states, while climate change involves the entire energy basis of modern life.
To achieve abolition, I believe we must recreate the anti-nuclear movement, but in a fundamentally different way. This can’t be a left-wing peace movement. It needs to be politically diverse. After all, no sane person is in favor of collective suicide. It also needs to be anti-nuclear only in the sense of opposing weapons, not nuclear power. Far too many green groups have got this backwards. We need nuclear power stations both to tackle climate change and burn up decommissioned nuclear warheads in their fuel. The resulting energy is carbon-free, so we could be helping solve the climate crisis while we solve the nuclear weapons threat.
It’s already the official policy of the United Nations to have nuclear abolition, thanks to the Treaty on the Prohibition of Nuclear Weapons (TPNW). The TPNW was adopted in 2017 and entered into force in 2021. It has 93 signatories and 70 full state parties. That’s nearly half the world. In its Article 1, each state party undertakes never to develop, test, produce, possess, transfer, use, or threaten to use nuclear weapons under any circumstances.
We can’t stop wars, but we can stop a war that destroys the biosphere. Presidents Gorbachev and Reagan realized this when they met in 1985 and issued a statement saying that nuclear war cannot be won and therefore should never be fought. Logically, if you can’t fight the war, you don’t need the weapons. The only way to fulfill that is to get to total abolition.
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