Nuclear Winter Could Devastate Global Food Production

Nuclear winter and global food production

It is tempting to think that nuclear war would affect only people near enough to witness its most horrifying cloud. In fact, the destruction could extend across the entire planet.

New research illustrates how severely global food production could suffer under a range of nuclear winter scenarios.

Nuclear winter is a catastrophic climatic effect predicted to follow a major nuclear conflict. Nuclear detonations and the firestorms they trigger could send vast quantities of soot and dust into the atmosphere. This would limit the sunlight reaching the ground for years, killing many plants and animals – including those on which people depend for food.

Corn used to model agricultural losses

A new study led by researchers at Pennsylvania State University in the US modelled the effect of nuclear winter on worldwide food production. As the most widely cultivated grain globally, corn (Zea maize) served as a 'sentinel' crop, enabling the researchers to estimate the wider consequences for agriculture.

"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.

Predictably, the findings were bleak. A localised nuclear war that released 'only' 5.5 million tonnes of soot into the atmosphere would still lower global corn production by 7 percent. A worldwide conflict releasing 165 million tonnes, by contrast, could reduce crop production by 80 percent.

Ozone loss could worsen crop damage

The most extreme scenario carries an additional damaging effect: 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 researchers calculate that UV-B radiation would reach its highest level six to eight years after a nuclear war, cutting corn production by a further 7 percent. That would mean an alarming total reduction of 87 percent in crop production, creating a global food crisis.

The models indicate that worldwide corn production could need between 7 and 12 years to recover from nuclear winter, depending on the conflict's severity. In general, recovery would be quicker in the Southern Hemisphere than in the Northern Hemisphere, and faster nearer the equator than nearer the poles.

Agricultural resilience kits for recovery

People could nevertheless take steps to accelerate recovery. Replacing corn with varieties better suited to cooler temperatures and shorter growing periods could cut the loss of crop productivity by up to 10 percent. While that could offer some help, avoiding a nuclear winter altogether would plainly remain preferable.

Should it become necessary, however – and the present state of global politics makes this prospect more likely than at any point since the Cold War – the team recommends preparing "agricultural resilience kits." These would contain crop seeds selected as the best regional match for projected climatic conditions.

"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 is asked: nuclear winter would not offset global warming.

The study was published in the journal Environmental Research Letters.