Winter is coming, and that’s bad news for food security

Two recent papers take different approaches to the potentially disastrous consequences of loading the stratosphere with ash but combined, they act as a warning for the fragility of food security.

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Winter always comes with the turning of the seasons, but what if it doesn’t leave? 1816 was known as ‘the year without a summer‘ after ash spewed by the eruption of Mount Tambora caused cloud cover that dramatically cooled the climate. This week, two papers consider the danger of ash in the stratosphere and the effect it could have on food security.

Lili Xia, Alan Robock, and colleagues published a study of the effects of a nuclear winter in Nature Food. A nuclear winter would be created by firestorms caused by detonations over cities. The gigantic fires caused by the nuclear explosions would cause massive quantities of soot to rise into the stratosphere, reducing sunlight and temperatures.

The authors used six hypothetical wars to model how nuclear exchanges could affect climate, crop and marine production. They write, “The reduced light, global cooling and likely trade restrictions after nuclear wars would be a global catastrophe for food security. The negative impact of climate perturbations on the total crop production can generally not be offset by livestock and aquatic food. More than 2 billion people could die from a nuclear war between India and Pakistan, and more than 5 billion could die from a war between the United States and Russia.”

A gentleman holding a mask looks out from ruins towards a gutted industrial building obscured by falling snow. The photo is in black and white to emphasise the grittiness of the scene.
Artist’s impression of a nuclear winter. Image: Canva.

Crop declines would be the most severe in the mid-high latitude nations, including major exporting countries such as Russia and the U.S., which could trigger export restrictions and cause severe disruptions in import-dependent countries in Africa and the Middle East.

In contrast, the researchers told Nature News that Australia remains viable for wheat. The maps showing the effect of a nuclear war on world hunger show Australia to be green in all cases. Argentina also does well.

However, the results also show that there is no such thing as a good nuclear war. Even a small war between India and Pakistan would result in a global drop in food production of 7% of calories. “The data tell us one thing: We must prevent a nuclear war from ever happening,” said Alan Robock.

Whether or not there is a nuclear war is a matter of choice, but a second paper discusses another winter that may happen whether we want it or not. Michael Cassidy and Lara Mani compare the money spent on early warning of asteroid strikes with the lack of preparation for a colossal volcanic eruption. The eruption in Tonga in January was the largest eruption instrumentally recorded. “The Tonga eruption was the volcanic equivalent of an asteroid just missing the Earth, and needs to be treated as a wake-up call,” said Mani in a press release.

Stop motion satellite photography of the eruption on Tonga. A circular cloud of ash gets bigger as the eruption develops.
The GOES-West satellite captured this imagery of the Tonga volcanic eruption on Jan. 15, 2022. Learn more about this image at NASA Earthdata. Credits: NASA Worldview, NOAA / NESDIS / STAR

Scientists at the University of Cambridge’s Centre for the Study of Existential Risk (CSER) have been examining ice cores for tell-tale fingerprints of past volcanic explosions. By tracking spikes of sulphur concentrations in the ice, they have found that an eruption between ten and a hundred times greater than the Tonga eruption occurs around every six hundred years on average. It would be nice to think that because a big eruption happened in the 1810s, we don’t have to worry till 2400, but sadly this is not the case.

In their nuclear winter paper, Xia, Robock, and colleagues conclude that a combination of reduced light, global cooling and likely trade restrictions would cause chaos for food security after a nuclear war. If a colossal volcano eruption could have a similar effect to a small nuclear war, then it seems reasonable to ask what is being done to prepare for a volcanic winter, which is likely sooner or later.


Cassidy, M. and Mani, L. (2022) “Huge volcanic eruptions: time to prepare,” Nature, 608(7923), pp. 469–471.

Xia, L., Robock, A., Scherrer, K., Harrison, C.S., Bodirsky, B.L., Weindl, I., Jägermeyr, J., Bardeen, C.G., Toon, O.B. and Heneghan, R. (2022) “Global food insecurity and famine from reduced crop, marine fishery and livestock production due to climate disruption from nuclear war soot injection,” Nature Food,

Translations by Google Translate.

Alun Salt

Alun (he/him) is the Producer for Botany One. It's his job to keep the server running. He's not a botanist, but started running into them on a regular basis while working on writing modules for an Interdisciplinary Science course and, later, helping teach mathematics to Biologists. His degrees are in archaeology and ancient history.

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