Nuclear war is a nightmare, but the explosions are just a prelude to something worse—decades of irradiated land and possibly dramatic climate change. If a nuclear powered country launches enough of the deadly weapons, it’s possible to screw up the planet badly enough to trigger a nuclear winter and starve its own population. When it comes to nuclear war, nobody wins.
The effects of a nuclear attack on the aggressor nation and the resultant agricultural fallout is the subject of a new study published in the academic journal Safety called “A National Pragmatic Safety Limit for Nuclear Weapon Quantities.” According to the researchers, any country holding on to more than 100 nuclear warheads and planning to use them is asking for trouble.
Lots of studies have looked at the effects of nuclear weapons, but few have considered what would happen to the country that used them. There’d be political consequences, for sure, but researchers Joshua M. Pearce and David. C. Denkenberger argue that the environmental impact could be far worse. “Using more than 100 nuclear weapons by any aggressor nation even with optimistic assumptions would cause unacceptable damage to their own society,” the study said.
It all comes down to nuclear winter and nuclear autumn. This is the idea, backed by numerous scientific studies, that any large scale detonation of nuclear weapons as might happen in a thermonuclear war between superpowers would cause radical changes to climate. The bombs themselves would throw soil in the atmosphere, but the resultant firestorms would be worse. “These fires would produce a thick smoke layer in the Earth’s atmosphere, drastically reducing sunlight reaching the earth’s surface causing what they called ‘nuclear twilight,’" the study explained.
Pearce and Denkenberger found that even a small number of nuclear weapons, around 100 they say, would have dramatic consequences for the planet. “Even a small regional conflict or a very limited nuclear strike by a single country has the potential to cause mass starvation worldwide through environmental effects—including, of course, in the country of origin of the bombs,” they said.
For the study, the researchers imagined a “best-case” scenario for nuclear war where an aggressor nation launched its nukes and nothing went wrong. In their scenario, there were no accidents, all the nukes hit their targets, and the target country is so totally destroyed that it can’t retaliate.
According to their conservative estimates, 100 nukes hitting their targets would put about 7 trillion grams of soot into the air. “This would be more than sufficient to produce the lowest temperatures Earth has experienced in the past 1000 years,” the study said. “It would result in a 20% drop in sunlight and lead to a 19% drop in global precipitation.”
That radical change to the environment would lead to an agricultural shortfall, a spike in food prices, and panic among the population. The researchers pointed out that America is well positioned to survive such a catastrophe thanks to its large amount of arable land, but would still face increased food insecurity and possible rationing.
Pearce and Denkenberger studied the effects of nuclear war on the food chain after they’d written the book Feeding Everyone No Matter What, which looks at what the world needs to do to feed its entire population. “Our results were mostly good news—it is possible to keep all of humanity alive using alternative foods like growing bacteria on natural gas,” Pearce told me via email. “Oddly, the highest probability of having such a global catastrophe was also the one we have the most control over: nuclear weapons. We knew the use of a large number of nuclear weapons would bring on nuclear winter but were interested in how a relatively small number of weapons would play out on the food supply.”
They wanted to find out what number was the smallest possible number of nuclear weapons any country should have to maintain deterrence without destroying the global food supply should they be used. They settled on 100. The pair poured over older Pentagon studies and were surprised at how few looked at what might happen in the aggressor country in the event of nuclear war. “Given our results, it is pretty clear that the Pentagon had not looked at the potential for what we are call 'nuclear autumn' very closely,” Pearce told me. “This was the first study to look at only a one sided nuclear attack and its effects specifically on the food supply.”
According to the researchers calculations, 100 nukes should be more than enough to prevent anyone from attacking a nuclear superpower. They estimated that 100 typical nukes detonated in China would kill more than 34 million people. “All other potential enemies would be subjecting an even larger fraction of their population to annihilation. Thus, not all 100 would not need to be launched.”
Pearce and Denkenberger’s warning is important and the world has far more nukes in it than 100 per nuclear power. Of the more than 14,000 extant nuclear weapons, Russia and the US have more than 6,000 each with around 1,000 deployed at any given time. North Korea and Israel are on the low end with fewer than 15 and around 80 respectively.
But it’s hard to get politicians to listen to scientists, especially when it comes to the deleterious effects of nuclear weapons. “The results of this paper show that even just focusing on self-interest alone should be enough,” Pearce said. The bottom line is that nuclear war won’t be one sided—the country launching the nukes will get hurt too and the more nukes the greater the negative impact.
For Pearce, it’s about making politicians understand that firing nukes abroad could lead to starving citizens at home. “Politicians would never condone starving potentially millions of their own citizens by firing a large percentage of their nuclear stockpile,” he said. “Continuing to spend billions of dollars to maintain so many superfluous nuclear weapons we would never use because it would destabilize America makes no sense.”