Nuclear war expert explains why Australia and New Zealand may be the last places left standing after WW3

If World War III were ever to break out, where on Earth would actually be safe? It’s the kind of uneasy question that slips into public consciousness during missile alerts, diplomatic stand-offs and late–night doomscrolling. With Russia’s invasion of Ukraine reshaping European security, China openly signalling moves toward “reunification” with Taiwan, Iran–Israel tensions simmering, and North Korea firing ballistic tests like flares in the dark, fears of a major global conflict are no longer hypothetical, they are ambient.

In that atmosphere, nuclear planners and climate modellers have long run simulations of a full nuclear exchange. But few people outside that world know how such scenarios play out minute by minute. One person who has tried to make that grim future legible for ordinary readers is Annie Jacobsen, the US investigative journalist whose reporting suggests that, if the worst unfolds, billions would die within just over an hour. And in that world, she argues, only a handful of places, most notably Australia and New Zealand, might realistically sustain human life on a meaningful scale.

Her case is not rooted in “prepper lore” or online survivalist fantasy. It rests on launch trajectories, presidential decision windows, firestorm physics, ozone depletion, and nuclear-winter food modelling. What emerges is not a dramatic movie reel, but a slow, horrifying logistics problem: 72 minutes of cascading missile launches… followed by years of cold, radiation exposure and agricultural collapse, starvation, and ultimately...

Who Annie Jacobsen is, and why anyone listens to her

Annie Jacobsen is not another armchair doom-poster. She has spent years reporting on the US national security state: secret weapons, covert programmes and how militaries think about the future.

Her 2015 book The Pentagon’s Brain: An Uncensored History of DARPA, America’s Top Secret Military Research Agency was a Pulitzer Prize finalist, with Columbia University’s awards committee calling it a “brilliantly researched account” of the Pentagon’s most experimental arm. She now serves on a Columbia University prize committee and has written multiple books on intelligence, black programmes and war planning.

Her latest book, Nuclear War: A Scenario, takes that reporting to its logical extreme. It is a minute-by-minute narrative of a hypothetical nuclear exchange, built from declassified documents, technical studies and interviews with physicists, missile experts and former Pentagon figures. The scenario itself is fictional, no one knows exactly how a real crisis would unfold, but every parameter inside it is real. That is why Jacobsen’s conclusions have landed with such force.

Seventy-two minutes to catastrophe: how her war begins

In Jacobsen’s scenario, the trigger is North Korea. A leader in Pyongyang decides to launch a surprise nuclear attack on the United States: an intercontinental ballistic missile aimed precisely at the Pentagon, and a submarine-launched missile targeting a major nuclear reactor in California. The “why” is left deliberately vague. The point is not the politics of one sudden crisis but the machinery that inevitably springs into action once any nuclear launch is detected.

From there, the clock is brutal.

Speaking to Politico, Jacobsen notes that the key physics have barely changed since the early Cold War. “It takes 26 minutes and 40 seconds for a ballistic missile to get from a launchpad in Russia to the East Coast of the United States,” she said. That was true when nuclear physicist and Pentagon adviser Herb York first ran the numbers in 1959–60, and it is true now. From North Korea to the US, she adds, “Pyongyang is 33 minutes because it’s a little bit different geographically.”

As soon as early-warning systems detect launches, US command protocols snap into place. Satellites and radar confirm this is not a glitch. The president is moved to safety. The “nuclear football,” the briefcase containing strike options, is opened. From the first warning, the decision window is measured in minutes.

“Part of the terrifying truth about nuclear war,” Jacobsen told Politico, “is the insane time clock that was put on everything from the moment nuclear launch is detected… the president has only six minutes, that’s the rough time to make this decision. And in that time, the Black Book gets opened; he must make a choice from a counterattack list of choices inside the Black Book.”

In the book’s scenario, the president authorises a massive retaliatory strike against North Korea’s nuclear and military infrastructure – including 82 targets in total. Those American missiles suddenly arc over Russia. Russian systems, seeing a swarm of US ICBMs inbound and unable to get the US president on the phone, interpret this as an attack on them. They launch immediately back. Within just over an hour, three nuclear-armed states have sent enough warheads to kill billions.

On Steven Bartlett’s Diary of a CEO podcast, Jacobsen describes the first detonation in almost clinical detail. The opening weapon, she says, is “a one megaton thermonuclear bomb” over the Pentagon. Drawing on US Defence Department documents and interviews with defence scientists, she describes “the initial flash of thermonuclear light – which is 180 million degrees, which catches everything on fire in a 9 mile diameter radius,” followed by blast waves flattening buildings, fires feeding more fires and radiation killing people “in minutes and hours and days and weeks if they happen to have survived”.



By minute 72 in her scenario, she says, “a thousand Russian nuclear weapons land on the United States”, producing overlapping 100–200 square-mile firestorms. At that point, the immediate death toll is in the hundreds of millions. But the longer-term damage, she argues, is worse.

After the fire: nuclear winter and five billion dead

Jacobsen’s book doesn’t stop at blast zones and mushroom clouds. It leans heavily on work by climate scientist Professor Brian Toon and colleagues, including a 2022 paper with researcher Ryan Heneghan that models nuclear winter and the collapse of food systems.

The mechanism is straightforward and horrifying. City-scale firestorms throw vast quantities of soot and smoke into the upper atmosphere, where they block sunlight for years. Average temperatures fall. Growing seasons shrink. Rainfall patterns change. Major grain belts in the mid-latitudes – including regions like the American Midwest and Ukraine – become, in Jacobsen’s words, “just snow for 10 years.”

“Agriculture would fail,” she told Bartlett, “and when agriculture fails people just die.”

Toon and Heneghan’s modelling, which she cites in interviews, estimates that around five billion people could die not from blast or radiation but from famine and related effects. Fisheries are disrupted. Global trade collapses because there is almost nothing left to trade, and because infrastructure, ports and insurance systems no longer function. Even countries not directly hit by warheads face cascading shortages.

In that world, Jacobsen says, the survivors are not the lucky ones. She quotes former Soviet leader Nikita Khrushchev’s grim line that, after a nuclear war, “the survivors would envy the dead”.

On Diary of a CEO, she expands on that: with governments destroyed and law and order gone, those who remain are “returning to the most primal, most violent state, as people fight over the tiny resources that remain… they’re all malnourished, everybody’s sick and most people have lost everything and everyone they know.”

Even those with access to bunkers or hardened facilities, she argues, would eventually have to come back up to the surface, into a world where sunlight is weak, food is scarce and social systems have collapsed.

Why her model singles out Australia and New Zealand

Against that backdrop, one line from Jacobsen’s interviews has understandably gone viral: her claim that only two countries stand a realistic chance of keeping large populations alive after a full-scale nuclear exchange.

On Diary of a CEO, she recounts a conversation with Professor Brian Toon. “Only two countries could potentially survive a nuclear winter,” she says he told her – “New Zealand and Australia, who can ‘sustain agriculture’.”

She is not suggesting they would escape unscathed. Instead, she says their odds are less catastrophic than almost anywhere else, for three main reasons.

The first is geographical. Both Australia and New Zealand sit deep in the Southern Hemisphere, far from most likely nuclear targets and away from the densest launch corridors between North America, Europe and northern Asia. They are not immune to fallout or atmospheric changes – nuclear winter is global by definition, but they are physically removed from the primary blast zones.

The second is food. Both countries are major agricultural exporters in peacetime. They have relatively low populations compared with their productive land and surrounding waters. In Toon’s modelling, that surplus capacity gives them a better chance of keeping at least a fraction of their populations fed when global supply chains vanish and crop yields elsewhere collapse.

The third is infrastructure and energy. Australia and New Zealand have established grids, some domestic fuel and, particularly in New Zealand’s case, significant renewable generation. None of that guarantees resilience in a world of wrecked satellites, broken cables and political chaos, but it gives them more room to adapt than states that depend heavily on imported food and fuel.

In practice, Jacobsen still imagines life there as brutally hard. When she says people would be “forced to live underground fighting for food everywhere except in New Zealand and Australia,” the implication is not that the Antipodes would be comfortable. It is that, in a world of ice, darkness and famine, they might still be able to grow crops at all.

In Jacobsen’s terminology, “safest” isn’t absolute safety, but relative survivability, “the last places where life might continue at all.”

What Jacobsen thinks we should take from this

It would be easy to treat all of this as morbid fantasy. Jacobsen is careful to stress that Nuclear War: A Scenario is not a forecast and that no one – including generals and physicists, can know precisely how a real conflict would play out.

But she is also clear about what the exercise is for. Nuclear deterrence as a doctrine rests on an almost abstract phrase: “unacceptable damage”. The threat of mutual destruction is supposed to stop leaders ever pressing the button. By walking through a plausible 72-minute chain of decisions and misread signals, she is trying to put detail back into that abstraction.

Her work also undercuts the comforting idea that there are “neutral” havens. Even in past conventional wars, countries with little interest in fighting have been pulled in or hit by economic shock. In a nuclear exchange of the sort Jacobsen describes, there is no meaningful outside. Soot in the stratosphere, disrupted monsoons and collapsing harvests do not check passports.

So when she says, bluntly, that “five of the eight billion on Earth are likely to die in the first 72 minutes” of her scenario, and that only places like Australia and New Zealand might have the climate and agriculture to support large populations afterwards, she is not handing out relocation advice. She is translating decades of quietly compiled technical work into something ordinary people can understand – and, ideally, into pressure to make sure none of it ever has to be tested.

FAQ

Could a nuclear war really unfold in seventy-two minutes?

Analysts emphasise that no one can script the exact timeline of a nuclear exchange. But missile flight durations, roughly 25 to 35 minutes for most intercontinental launches, are fixed by physics. Once any launch is detected and confirmed, national command systems compress decision-making into minutes. Jacobsen’s seventy-two-minute scenario is not a prophecy; it is an illustration of how quickly events can cascade once the first missile is fired.

Why would Australia and New Zealand fare better than most?

Their advantage is relative, not absolute. Both countries sit far from primary targets and northern-hemisphere missile routes. Both have strong agricultural bases and low population densities, which gives them better odds of producing food even in colder, darker conditions. They would still face shortages, instability and climate disruption, but their starting conditions improve their chances of keeping large populations alive.

Is there anything individuals can realistically do?

In a limited nuclear event, basic preparedness, sheltering indoors, short-term supplies, avoiding fallout, can make a difference. In a full-scale US–Russia exchange, however, the greatest threats come from nuclear winter, agricultural collapse and global economic breakdown. Personal survival plans offer only marginal protection. The only real safeguard is political pressure to reduce nuclear arsenals and prevent escalation in the first place.