spaceSpace and Physics

What Would Happen If Every Single Nuke In The World Went Off At The Same Time?


Robin Andrews

Science & Policy Writer


The mushroom cloud of one of the French military's nuclear weapon tests above the atoll of Mururoa in 1971. Galerie Bilderwelt/Getty Images

Have any of you seen the movie Dr. Strangelove (Or How I Learned To Stop Worrying And Love The Bomb)? It’s a classic film, one that satirizes the nuclear arms race in the Cold War. Spoiler alert: A chain of unfortunate events ends up causing every single nuclear weapon around the world to detonate, leaving humanity pretty screwed.

With Trump’s recent and terrifying comments about boosting the US nuclear arsenal and not ruling out using any of these weapons in the Middle East or Europe, we felt it best to work out – for your horror – what would happen in the event of a nuclear apocalypse. What would happen if every nuclear weapon in the world today was fired and detonated?


In short, nothing good. Here’s the rather grim mathematics and science behind the end of the world.

From Russia With Love

No fighting in the war room. liberalartist6 via YouTube

First, let’s have a look at what various countries have in their nuclear arsenal.


As per the Federation of American Scientists’ 2017 data, there are 14,900 nuclear warheads in the world. The US has 6,800 and Russia 7,000, making up the vast majority of the world’s city killers. The UK has 215, France 300, China 260, India 120, Pakistan 130, Israel about 80, and North Korea roughly 10.

The yields of each of these vary considerably. The US and Russia, for example, have hyper-powerful thermonuclear weapons, whereas North Korea can barely get past an old-school plutonium fission-style device.

One of the most powerful weapons in the US arsenal is the B83, which has an explosive yield equivalent to 1.2 megatons of TNT. This equates to about 5 quadrillion joules of energy, or 5 Petajoules – or 79 Hiroshima “Little Boy” atomic bombs’ worth of energy.

Say one of these B83s went off in Moscow, because President Trump lost a Twitter war with President Putin and everything escalated rather quickly. If it detonated at the surface, it would leave a crater 420 meters (1,378 feet) across and 92 meters (300 feet) deep, according to NukeMap by nuclear historian Alex Wellerstein.


Almost instantly upon detonation, a gigantic fireball would appear, 5.7 square kilometers (2.2 square miles) in size and reaching temperatures up to 83.3 million degrees Celsius (150 million degrees Fahrenheit).

Using up 50 percent of the entire warhead’s energy, it would also be accompanied by a huge pressure wave. All buildings within a 16.8 square kilometer (6.5 square mile) area would be totally flattened.

Thanks to the thermal radiation – which uses 35 percent of the explosive's energy – everyone within a 420 square kilometer (162 square mile) region will receive third-degree burns, which will only be painful for a fraction of a second as their nerve endings will be completely destroyed.

Then there’s the ionizing and fallout radiation. Assuming there’s no wind at the time, we can assume that an area of 20.6 square kilometers (8 square miles) will be so heavily irradiated that 50 to 90 percent of people in it will die from radiation sickness.


A nuclear weapon detonation - test Baker - conducted by the US military just offshore Bikini Island. US Army

We’ll Meet Again

Ok, so now let’s destroy the world.

In order to get a very rough explosive yield for all the world’s nukes, we’ll only include the US and Russia’s, but assume they are each as powerful as the B83. That’s 13,800 thermonuclear bombs, altogether producing about as much energy as the entire US does in an entire year.


Each of these devices will hit land and detonate at the surface. Assuming they’re evenly spaced out across the world’s cities and towns, and maybe a village or two, this will annihilate 94 kilometers (23 cubic miles) of land immediately – but that’s nothing compared to what happens next.

232,000 square kilometers (90,000 square miles) of infrastructure will be blown away by the air blast. That’s about 295 metropolises the size of New York City turned to dust.

A fireball 79,000 square kilometers (31,000 square miles) will vaporize literally anything it touches, and anyone within a 5.8 million square kilometer (2.2 million square miles) area would get third-degree burns. So everyone in the same space as 3,700 cities the size of London would be scorched.

Lastly, the fallout and ionizing radiation would contaminate an area of the world about 284,000 square kilometers (110,000 square miles) in size and give most of the initial survivors radiation sickness. Of course, a lot of this fallout would reach the lower atmosphere and spread across the world, so casualties would be far higher in the long term.


So at the very least, hundreds of millions, perhaps billions, will die within the first hour. This is awful enough as it is, but what happens next?

Winter is Coming

Nuclear winter is a hypothetical phenomenon that is somewhat like a volcanic winter. During the most epic of eruptions, plenty of aerosols and fine particulate matter is produced. They are incredibly reflective, and if they manage to get into the upper atmosphere, the net result is that they cool the planet.

Historically, humans have witnessed volcanic cooling for several years at a time. Before we existed, there were several mass extinction events driven partly by volcanic effusions that – while also warming it with a huge expulsion of carbon dioxide – cooled the world for many hundreds of years at a time, perhaps longer.


A nuclear winter is essentially the same, except that the world will only cool and the particulate, ash-like matter will be radioactive. Breathe enough of this in and you’ll quickly die. So how many nuclear fireballs are needed to initiate a powerful enough nuclear winter?

One study suggests that 100 Hiroshima-style blasts will produce enough black carbon soot to cause a “small” nuclear winter. This would reduce the global average temperature by roughly 1°C (1.8°F), offsetting the recent bout of man-made global warming – problem solved, then?

If every single one of the world's nukes went off, then, there will be a near-100 percent reduction in solar radiation reaching Earth’s surface for several years, meaning the planet would be shrouded in perpetual darkness for that time. Light would creep in increasingly, but slowly over the next few decades or even centuries.

Video games have often looked into possible post-apocalyptic futures. Bethesda Softworks via YouTube


Suffice to say, this would all but stop photosynthesis. Only the hardiest of plants would not die out, which would lead to a collapse in the global food chains. There would be a mass extinction event – including perhaps our own species – and the survivors would have to fend for themselves in an irradiated landscape.

So yeah, not great. Let’s hope President Trump doesn’t treat the nuclear button as impulsively as he fires off tweets.


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