Science

"Nuclear winter" would starve billions, but some countries may be spared

Modeling estimates five billion people would die of hunger due to global food supply disruptions following a serious nuclear conflict
Modeling estimates five billion people would die of hunger due to global food supply disruptions following a serious nuclear conflict

If a nuclear war were ever to break out, it probably wouldn’t last long. For a few days, perhaps a week, nuclear weapons would be fired between several countries and catastrophic losses would be swift. But what happens next?

For decades researchers have been modeling the after-effects of nuclear conflict. One of the most globally devastating outcomes from a nuclear war is the possibility of a prolonged climactic cooling event referred to as “nuclear winter.”

“In a nuclear war, bombs targeted on cities and industrial areas would start firestorms, injecting large amounts of soot into the upper atmosphere, which would spread globally and rapidly cool the planet,” researchers explain in a new study. “Such soot loadings would cause decadal disruptions in Earth’s climate, which would impact food production systems on land and in the oceans.”

Although the term “nuclear winter” was coined in the 1980s, the idea is as old as nuclear weapons. As far back as 1947 science fiction author Poul Anderson speculated about the prospect of a global nuclear war triggering a new ice age in his iconic post-apocalyptic story Tomorrow’s Children.

Recently, as climate modeling has become more sophisticated, researchers have been able to run more complex simulations to explore what kinds of effects a possible nuclear winter would have on environmental conditions around the world. This new study offers the most detailed modeling to date, investigating how nuclear war could effect global food supplies.

The study simulated six nuclear war scenarios, each producing varying levels of soot in the stratosphere. Five scenarios modeled different scales of nuclear conflict between India and Pakistan, while the sixth model simulated a global nuclear war between the US and Russia.

Each model estimated the climate effects from soot being kicked up into the atmosphere. These climate changes were then fed into agriculture models designed to calculate reductions in major crop productions, such as wheat, rice and corn. Ultimately, the study translated those crop reductions into total losses of calories produced, meaning the researchers could then estimate how many people would hypothetically succumb to famine in the months, or years, following a nuclear war.

The worst-case scenario modeled in the study looked at the effect of 150 million metric tons of soot being injected into the stratosphere following a week of global nuclear conflict. While around 360 million direct fatalities could be estimated from the acute dropping of nuclear bombs, the climate effects from the weapons would result in a nearly 90% drop in global calorie production. Two years after the nuclear conflict the modeling estimates around five billion people would die from famine around the world.

“Although the likelihood of such a war is low, a 14.8 °C (26.6 °F) global cooling (an ice age) would ensue within one to two years after the nuclear blasts,” explained Deepak Ray, an environmental scientist commenting on the new modeling. “Even if half the livestock feed calories were diverted and consumed as human food, and all food wastage was also consumed, the authors calculate a shortfall in calories of close to 74% in this extreme 150 Tg scenario.”

However, the modeling does indicate not all countries will face similar experiences of food insecurity following nuclear conflict. In the most extreme nuclear scenario the model predicts all international trade of food would cease, leaving each country relying on its own ability to produce calories for its people.

The one country seemingly most protected from the global catastrophe predicted in the modeling is Australia. The researchers estimate wheat production in Australia to be largely unaffected by nuclear-related climate changes, leaving the country able to effectively produce enough calories to sustain its population. Neighbor New Zealand was also modeled to be relatively secure in the most extreme scenario modeled.

Of course, the study does point out this wouldn’t mean Australia is completely protected if a scenario such as this ultimately played out. The researchers speculate countries with consistent food supplies, such as Australia and New Zealand, would likely experience significant influxes of refugees from nearby Asian nations facing famine.

The researchers behind the new study are well-aware of the limitations in this kind of modeling. The scenarios simulated focus solely on the impact of nuclear winter on current caloric crop production. While this calorie deficit cannot be offset by livestock or increases to aquatic farming, the researchers do speculate on the potential for alternative food sources being introduced, such as pivoting to producing food requiring little to no sunlight.

Ultimately, study co-author Alan Robock, who has been modeling the climate effects of nuclear war for decades, said there is no simulation that isn’t incredibly damaging to global stability. He said billions of people would likely die in the aftermath of nuclear war due to food insecurity, and this is why these weapons must be banned.

"If nuclear weapons exist, they can be used, and the world has come close to nuclear war several times," Robock stressed. "Banning nuclear weapons is the only long-term solution. The five-year-old UN Treaty on the Prohibition of Nuclear Weapons has been ratified by 66 nations, but none of the nine nuclear states. Our work makes clear that it is time for those nine states to listen to science and the rest of the world and sign this treaty."

The new study was published in the journal Nature Food.

Source: University of Rochester

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16 comments
anthony88
Yes, Australia would survive because major cities (where about 95% of the country's population lives) with military infrastructure nearby would be destroyed and their populations decimated. The largest ICBMs have around 5 MIRVs. If I were targeting the naval infrastructure on Garden Island, Cockburn Sound, I'd put one on the base, one on the nearby industrial area in Kwinana. I'm now left with 3 MIRVs. Where am I going to put them? If it's possible to spread MIRVs out far enough, I'd put one on Pearce Airbase. Between Pearce Airbase and Garden Island is the administrative hub of the country's biggest industry, the mining industry, Perth CBD. I'd spare the largely undefended mine sites to the north so I could plunder them. The last one would go to either Swanbourne Barracks, Fremantle Harbour, or Perth Airport. I'd probably spare Perth Airport and Fremantle Harbour for the rapid deployment of a small invasion force that would quickly be able to subjugate a remaining shellshocked populace that was suddenly left without the ability to go to the local coffee shop and get their morning latte. If they thought lockdowns and mask mandates were bad, something tells me they won't like WWIII. Do you want my thoughts on what I'd expect the targeting plan is for Sydney? (Hint: It doesn't involve a couple of mini-subs.) None of this is fun. If we don't strive for peace now and the total removal of nuclear weapons, our future and that of future generations is uncertain.
Ric
Um, am I the only one thinking there must be a way to use this phenomenon as a way to initiate a minor cooling event to buy us a few more decades to prevent the melting of the polar ice caps and permafrost (and dial back all the severe weather events) while we get our carbon levels down? Is there a pitfall I’m missing??
JeremyH
Someone is going to conclude that this could be the swiftest way to restore the natural balance which has been so distorted by our species...
hijack
About 45 years ago, an American Professor moved to Tasmania, deeming it the safest place on the planet.
Another learned gentleman, (maybe David Suzuki), concluded if all trade were to cease worldwide, Australia/New Zealand & Canada would be the only places on the planet to survive as they were capable of feeding their population without importing food.
MrB
Ric & JeremyH: What about the huge amount of radioactive pollution you would also inject into the atmosphere? How would you determine what patch of land to 'carbonise', hold a worldwide lottery, winner gets flash vaporised? You couldn't pick any point on the planet where you could 'safely' detonate anything big enough to the create the effect anyway (the early nuclear tests were obviously nowhere near big enough or we wouldn't be in this pickle), and I doubt you could convince a country to volunteer itself 'for the good of humanity'.
That said, given the situation in Ukraine, we may not need to choose one soon...
martinwinlow
@ anthony88 - No, thanks... and what's a MIRV anyway?

@ Ric - Yes. And Yes... the pitfall is the small issue of the elimination of 6B people not to mention 95% of the rest of the planet's flora and fauna.

@ JeremyH - Well, maybe.... Putin? But do you 3 all know each other or something?

Meanwhile, bang goes the plot to Nevil Shute's 'On the Beach'...
Brian M
5 Billion perish, so that still leaves about 3 billion of us so planet won't be quite free of us yet.

The death toll in the following years will mount of course with the increased levels of radiation due to the world wide fall out.
How that will impact on the population not sure, but some of those survivors may not be able to reproduce due to radiation and not all will be of
reproductive age. But I suspect there will be enough to continue the human species.

If nothing else global warming will no longer be an issue and nature will adapt, it always does, its just whether we as a species are part of it.
wowlfie
Well, nuclear winter would be a great way to quickly solve the global warming problem heh?
Captain Obvious
Putin's thinking, this is the way to get rid of Ukraine and get the Nobel for Physics too.
Mark Markarian
Have you noticed how gingerly we've been involved in the Ukraine / Russian War? That's because nobody wants it to escalate to nuclear. Nuclear weapons are the reason peace broke out in the 2nd half of the 20th Century and continues to this day. Yes, I know Korea, Vietnam, 9/11 and other wars have broken out, but nothing in the World War realm. That's because everyone knows WW3 will be a war without winners.

So don't expect it to come, but we must always be vigilant in preventing it's start.