US needs to cut its nukes by 98% if the world is to avoid a nuclear winter

There are currently around 15,000 nuclear weapons dotted across the globe, mainly split between the US and Russia, with 6,550 and 7,010 respectively. That’s a lot of bombs – more than enough to punt the earth into a nuclear winter and decimate life on our planet.

US needs to cut its nukes by 98% if the world is to avoid a nuclear winter

Researchers at Michigan Technology University argue that a less self-destructive figure would be 100 per nation. That figure would still be enough to destroy millions living in cities, and millions more through starvation, but would be small enough that the nation firing them doesn’t suffer a major blowback.

The grim reading, published in the journal Safety, looks to find a “pragmatic safety limit” for nuclear weapons. The number, they argue, is the amount needed to balance being an effective deterrence, with not destroying the planet to the extent that the aggressor faces unmanageable environmental repercussions.     

Their argument hinges on the idea of a “nuclear autumn” being less severe than a nuclear winter. In both, the destruction of cities would send large quantities of soot into the upper atmosphere, which would linger, block sunlight and decrease precipitation, in turn devastating crops and causing famine. The idea is that a nuclear autumn would still result in millions of deaths but not as many as a full-blown nuclear winter – and, for the nation firing weapons, there’s less of a chance that it will have an impact on their population.

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“With 100 nuclear weapons, you still get nuclear deterrence, but avoid the probable blowback from nuclear autumn that kills your own people,” says Joshua Pearce, professor at Michigan Technological University. “Defense expenditures post-9/11 show we care about protecting Americans. If we use 1,000 nuclear warheads against an enemy and no one retaliates, we will see about 50 times more Americans die than did on 9/11 due to the after-effects of our own weapons.”

In their model, the researchers calculated how much burnable material would be destroyed in a nuclear attack, and how much would result in soot being sent into the upper atmosphere. This was used to run crop simulations, predicting how food supply would be affected by reduced sunlight and rainfall, and how this would ripple into starvations.

According to this model, if the US fired 100 nuclear weapons on China’s most populated cities, more than 30 million people would be killed by the initial blasts. Sunlight would be reduced by between 10 and 20%, which could have an enormous impact on the already crippled country, but would not cause any US citizens to starve.


(Credit: Joshua Pearce and David Denkenberger)

Domestic fallout

A key part of all this is, as Pearce mentions, is the assumption that no one retaliates, and that domestic infrastructures continues to chug along unimpeded by the active nuclear war. The researchers admit that this is a pretty unrealistic set of requirements for their model, especially given how chaotic the circumstances would need to be for all of a nation’s nuclear weapons to be fired at once.

“We should be clear this analysis represents a severe underestimate on the number of dead Americans,” Pearce says. “We assume severe rationing, which is the best way to keep the most people alive when there is this level of food shortage. It means anyone who would die of starvation is immediately cut off from food.

“I don’t think rationing would go overly smoothly,” he adds. “A lot more people would die in violence internally than what we estimated based on lack of calories.”

All the same, the researchers use their model to argue for an enormous reduction in nuclear arsenals. If each nuclear nation were to have only 100 weapons, that would bring the current figure of 15,000 down to 900 or fewer. Even this drastically reduced number would be enough to destroy millions upon millions of people, and any more would likely harm the aggressor as much as the target.

“It is not rational to spend billions of dollars maintaining a nuclear arsenal that would destabilise your country if they were ever used,” says Pearce. “Other countries are far worse off. Even if they fired off relatively few nuclear weapons and were not hit by any of them and did not suffer retaliation, North Korea or Israel would be committing national suicide.”

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