A Nuclear Winter Could Destroy Much of The World's Food Supply

It is tempting to think nuclear war would only harm people near enough to witness that most frightening cloud. In fact, the destruction could ripple across the entire planet.

New research sets out how severely global food production could be hit under a range of nuclear winter scenarios.

Nuclear winter and global food production after nuclear war

Nuclear winter is a catastrophic climate effect expected to follow a large-scale nuclear war, when nuclear detonations and the ensuing firestorms drive vast quantities of soot and dust into the atmosphere. With less sunlight reaching the ground for years, many plants and animals would die off - including the species we depend on for food.

A new study led by scientists at Pennsylvania State University in the US modelled what nuclear winter would do to global food production. Because it is the most widely grown grain worldwide, corn (Zea maize) was treated as a ‘sentinel’ crop, enabling the researchers to infer likely impacts on agriculture more broadly.

"We simulated corn production in 38,572 locations under the six nuclear war scenarios of increasing severity – with soot injections ranging from 5 million to 165 million tons," says Yuning Shi, plant scientist and meteorologist at Penn State.

The projections, as you would expect, are grim. The researchers found that even a regional nuclear war - injecting ‘only’ 5.5 million tonnes of soot into the atmosphere - would still cut global corn production by 7 per cent. At the other end of the scale, a world-spanning conflict releasing 165 million tonnes could slash crop production by 80 per cent.

Ozone loss worsens the worst-case nuclear winter outcome

In the most extreme case, the damage is compounded by the breakdown of the planet’s protective ozone layer.

"The blast and fireball of atomic explosions produce nitrogen oxides in the stratosphere," says Shi. "The presence of both nitrogen oxides and heating from absorptive soot could rapidly destroy ozone, increasing UV-B radiation levels at the Earth's surface. This would damage plant tissue and further limit global food production."

The team calculates that UV-B would reach its peak between six and eight years after a nuclear war, trimming corn production by a further 7 per cent. That would mean an 87 per cent overall collapse in crop production - a level consistent with a global food crisis.

The modelling also indicates that global corn production could take between 7 and 12 years to rebound from nuclear winter, depending on how severe the war is. In broad terms, the Southern Hemisphere would recover sooner than the Northern Hemisphere, and areas nearer the equator sooner than those closer to the poles.

There are, however, actions people could take to shorten the recovery period. Moving to corn varieties better suited to cooler conditions and shorter growing seasons could lessen the loss in crop productivity by up to 10 per cent. That would help - though, plainly, the preferable option is to avoid nuclear winter altogether.

If it happens regardless - and today’s geopolitical climate makes the scenario more plausible than at any time since the Cold War - the researchers suggest assembling "agricultural resilience kits". These would consist of crop seeds selected to match each region under different anticipated climate outcomes.

"These kits would help sustain food production during the unstable years following a nuclear war, while supply chains and infrastructure recover," says Armen Kemanian, lead developer of the simulations. "The agricultural resilience kits concept can be expanded to other disasters – when catastrophes of these magnitude strike, resilience is of the essence."

And, before it comes up: no, nuclear winter would not offset global warming.

The study was published in the journal Environmental Research Letters.