Nuclear War Using Less Than 1 Percent of World's Arsenal Would Cause Global Food Crisis 'Unmatched in Modern History'

A nuclear war using less than one percent of the world's arsenal would have negative consequences for global security on a scale "unmatched in modern history," according to a study.

Such a conflict would have a significant environmental impact, causing the planet to rapidly cool while wreaking havoc on the world's food production systems, researchers said.

For a study published in the journal Proceedings of the National Academy of Sciences, a team led by Jonas Jägermeyr—from the University of Chicago and the NASA Goddard Institute for Space Studies—examined the potential consequences of a hypothetical nuclear conflict limited to one region of the globe using climate, agricultural and economic computer models.

"There is a new global nuclear arms race going on, many countries are investing in renewing their arsenals," Jägermeyr told Newsweek. "All treaties controlling nuclear weapons already expired, the one treaty left expires two months after the U.S. presidential election without any effort for renewal. Especially in South Asia tensions are extremely high and have escalated multiple times recently. Pakistan and India, as well as China and North Korea, are fueling a nuclear arms race."

Despite these trends, we don't have a clear understanding of what kind of indirect effects a regional nuclear war would have on food security around the world.

"Now we have the technological capabilities to do a sophisticated revision of earlier Cold War back-of-the-envelope calculations, but in a modern political context," Jägermeyr said. "My background is in climate change impact on global food systems. While we usually study global warming, the question of how sudden cooling would affect crop production and food systems is unresolved and therefore scientifically extremely interesting."

The plausible nuclear conflict scenario that the researchers examined would involve around 100 bombs with around 15 kilotons of explosive power—roughly equivalent to the one that was dropped on Hiroshima during World War II. While this may sound like a lot, it is only 0.7 percent of the global arsenal and around 30 percent of the combined arsenal of India and Pakistan.

According to the researchers, this conflict would result in widespread fires, releasing 5 million tons of black carbon, or soot, into the upper atmosphere. They say this would cause larger shocks to the global climate than those seen after historic volcanic eruptions, such as that of Mount Tambora (Indonesia) in 1815—which led to widespread crop failures, famine and economic hardship.

Notably, the global mean temperature would drop by nearly 2 C and precipitation would be reduced by eight percent for at least the first five years following the conflict.

"In a nutshell, soot emissions from fires will be lofted into the stratosphere where they distribute globally within weeks and once they entered the stratosphere they wouldn't fall out for a very long time—our models suggest 10-15 years," Jägermeyr said.

"Soot would partially block sunlight, which reduces the surface air temperature, and incoming solar radiation, but also changes the precipitation pattern globally, but most importantly in higher latitudes," he said. "All three factors add to losses in crop productivity, but temperature has the largest effect, because it causes crops in higher latitudes to fail to reach maturity and then run into frost events in the fall. Slightly reduced temperature could be beneficial for some crops in the tropics, but the negative effects at higher latitude are much worse."

As a result, even a limited nuclear war has surprisingly significant implications for global food security, according to Jägermeyr.

"Sudden cooling is harmful for crop production in higher latitudes, where our global breadbaskets are located—i.e. the United States, Canada, Europe, Russia and China—causing food losses unprecedented in documented history: around 11 percent on average for five years, exceeding the U.S. dust bowl event and large volcanic eruptions, but also surpassing adverse impacts from global warming," Jägermeyr said. "Global trade dependencies propagate the production shock to importing countries with often poorer populations in the Global South."

The researchers say that while current global food reserves would largely buffer production losses in the first year after the conflict, sustained losses in years two to five would fully deplete these, reducing food availability by more than 20 percent in 71 countries, with a total population of around 1.3 billion.

"This would cause severe health implications and potentially trigger additional tensions and conflicts," Jägermeyr said. "Because global food trade would basically come to a halt, food availability is shown to drop especially in food insecure countries depending on grain imports—for example, Libya, Niger, Somalia, Rwanda and Syria. This supports the conclusion, which is not part of the actual paper, that more people could die outside the conflict areas due to famine than due to the direct effects of the war."

Overall then, the study suggests that the indirect implications of nuclear war are greater than previously expected, in particular the impact on the global food production and trade system.

"There is no such thing as a confined nuclear conflict, 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—i.e., the United States, France, Russia, and China," Jägermeyr said.

Furthermore, he notes that this is the first study to demonstrate that sudden cooling is actually more harmful to global crop production than global warming, for the following reasons:

"Firstly, since the cooling is so abrupt, there is no/little time for adaptation—for example, switch to other crops, roll out new seeds at scale, develop cold-resistant varieties, move cropland to more suitable areas," he said. "Secondly, global warming negatively affects mostly the tropics where little of the overall global production happens, global cooling will affect the breadbasket regions at higher latitudes and thus has a much stronger impact on the global production."

"Thirdly, global warming is caused by higher carbon dioxide concentrations in the air, which has a beneficial effect for crop growth and might offset some of the adverse effects of climate change, global cooling would not have these beneficial effects," he added.