Even a small nuclear war could cause severe global food shortages


Study sounds warning about unstable nations with nukes.


Farmers in the Indian state of Madhya Pradesh separate rice from chaff.

Kevin Krajick/Earth Institute

By Natalie Parletta

As the nuclear arms race unfolds with renewed vigour, researchers have shown that even a limited, regional nuclear battle could cause severe global food shortages and more than a decade of famine exceeding the largest in history.

The treaty on the prohibition of nuclear arms is due to expire early next year, and with US President Trump signalling that he doesn’t intend to renew it in its current form, a Russian official warned recently that it is now too late to do so, reigniting fears of a Cold War.

But while these two countries control nearly 95% of the world’s nuclear warheads, there are grave concerns about escalating conflict in India and Pakistan, nations with significantly smaller arsenals that didn't sign the treaty at all.

Other nuclear-armed regions where tensions are high include China and North Korea, where excessive retaliation could trigger nuclear bombing.

“While this would be a humanitarian catastrophe,” says Jonas Jägermeyr from the University of Chicago and NASA, “the problem is that we don’t know what additional indirect effects even a small nuclear war might have, particularly for global food security.

Average changes in maize yield in the five years following a nuclear war between Pakistan and India.

Adapted from Jägermeyr et al., 2020

“Previous studies are simplistic, incomplete, or are just back-of-the-envelope calculations in the 80s.”

Jägermeyr teamed up with Alan Robock, an expert in nuclear war repercussions from Rutgers University, and a multi-disciplinary team to methodically explore this complex question, reporting their findings in the journal Proceedings of the National Academy of Sciences.

The scientists used state-of-the-art climate models to estimate the effects of soot injections into the atmosphere from 50 Hiroshima-sized nuclear bombs – now less than 1% of the world’s arsenal – then simulated the impacts of these climate anomalies on crop productivity using global crop models.

Extending beyond food production, they also tracked the repercussions of compromised food production on food reserves to get an idea of how food availability in each country would be impacted.

Results showed the firestorms would propel some five million tons of soot toward the stratosphere which would spread globally and remain there for at least five years and block sunlight, causing global cooling and altered rainfall.

“This is harmful for crop production in higher latitudes, unfortunately, where our global breadbaskets are located – US, Canada, Europe, Russia and China,” says Jägermeyr, “causing food losses unprecedented in documented history.”

They estimated that production of the world’s four main cereal crops – corn, wheat, soybeans and rice – would plunge on average by 11 percent over that time, with lingering effects lasting another five to ten years. And the cooling period would not offset global warming, just delay its impact.

Developed nations would likely impose export bans to protect their own populations and by year four after the conflict, 132 of 153 countries – totalling five billion people – would be impacted.

“As horrible as the direct effects of nuclear weapons would be,” says Robock, “more people could die outside the target areas due to famine, simply because of indirect climatic effects.”

It also suggests the cooling effect – a drop of 1.8 degrees Celsius – would be more damaging to global crop production than global warming, as crops will have no time to adapt to the sudden drop in temperatures, and global cooling impacts higher latitudes where the crops are grown.

Added to that, the carbon dioxide emissions that cause global warming can have beneficial effects on crop growth which could offset some of the adverse effects of climate change, says Jägermeyr, while global cooling has no buffering properties.

If nuclear weapons continue to exist at any scale, "they can be used with tragic consequences for the world," says Robock.

“There is no such thing as a confined nuclear conflict,” Jägermeyr warns; “as soon as soot emissions reach the stratosphere, implications unfold globally and hit food production hardest in countries that possess the bulk of the global nuclear arsenal.”

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Natalie Parletta is a freelance science writer based in Adelaide and an adjunct senior research fellow with the University of South Australia.
  1. https://www.armscontrol.org/act/2020-03/focus/one-wins-arms-race-nuclear-war
  2. https://www.nytimes.com/2019/11/01/world/europe/nuclear-arms-pact-expire-russia.html
  3. https://www.thestar.com.my/news/regional/2020/02/18/un-chief-039deeply-concerned039-over-pakistan-india-tensions-in-kashmir
  4. https://warontherocks.com/2019/11/might-india-start-the-next-south-asia-crisis/
  5. https://www.pnas.org/content/early/2020/03/10/1919049117
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