A study by a group of American researchers shows that Sweden would be one of the countries hardest hit by a nuclear war between the US and Russia. According to a simulation of such a scenario, 99% of Swedes would not survive, not because of the bombing itself, but mainly because of the global mass starvation that would follow.

In the study, published in Nature Food, the researchers assume that the nuclear war in question would be directed at cities, causing firestorms that would in turn produce huge amounts of soot in the upper atmosphere, blocking sunlight and cooling the planet. They conclude that a week of such warfare would reduce crop yields by 90%, even four years after the war had ended.

– Even countries far away from conflict regions are put at risk by nuclear conflict, says Lili Xia, co-author of the study.

In the researchers’ “nightmare scenario”, more than five billion people worldwide could starve to death after a nuclear war between the United States and Russia – but even a smaller nuclear conflict, for example between Pakistan and India, is estimated to destroy global food production and lead to up to 2.5 billion deaths. According to the study, food shortages would cause far more deaths than nuclear weapons themselves.

– The data tells us one thing: We need to prevent a nuclear war from ever happening, says climate scientist and study co-author Alan Robock.

What nuclear war looks like from space based on data from peer-reviewed science papers. A Nature Food paper today suggests that over 98% would starve to death in the US, Europe, China & Russia. pic.twitter.com/J0dtegXen4

— Future of Life Institute (@FLI_org) August 15, 2022

The war in Ukraine and the escalation over Taiwan have raised global fears of a nuclear conflict, and scientists say the whole world would be severely affected by such a scenario.

They also point out that wars, conflicts and coronavirus policies have already disrupted and negatively affected global food production, with almost 200 million more people facing food shortages than before and countries such as India and Malaysia restricting food exports. The fear of global conflict itself could also very likely lead to further export restrictions or bans and more countries choosing to keep all food for themselves.

– The psychological impact could be greater than the real damage, says food scientist William Chen, who believes that to cope with global instability, countries need to start focusing on more food sources, such as mushroom farms, large-scale indoor farming – and microalgae and insects.

– These do not require much space. They can be grown in your kitchen or underground and are less affected by an environment exposed to nuclear war, he argues.

‘Would cause unprecedented climate change’

It is estimated that there are between 12,000 and 13,000 nuclear weapons in existence today. According to the Stockholm International Peace Research Institute, Russia has 5,977 nuclear weapons and the US 5,428. China is thought to have around 350 nuclear weapons, France 290, the UK 225, Pakistan 165 and India around 160. Israel and North Korea also have nuclear weapons – 90 and 20 respectively, according to the Peace Research Institute’s own count.

– A full-scale nuclear war would cause climate change unprecedented in human history… In a US-Russian nuclear war, more people would starve to death in India and Pakistan alone than in the countries actually fighting the war, says Mr Robock.

The immediate effects of nuclear war have been widely recognised since the US dropped the ‘Little Boy’ bomb on Hiroshima in 1945. It killed an estimated 140 000 people in five months and destroyed two-thirds of the city’s buildings.

But it was only in the late 1980s that the long-term effects began to be studied in earnest, and in the worst-case scenario it is believed that radioactive dust and smoke would block out much of the sun’s light, causing temperatures to plummet and much of the world’s crops to simply die off – the same fate that is estimated could befall billions of people around the world.

In the worst-case scenario, a nuclear war between the US and Russia would cause the Earth’s surface temperature to drop by as much as 16 degrees Celsius – a huge impact on almost all life. The researchers behind the study also note that, in addition to starvation and disruption of social functions, large parts of the water system would become radioactive and unsafe to drink.

It is also estimated that the fires caused by the bombs release 100 to 1000 times the energy of the bombs themselves. When the huge amount of smoke is blown into the stratosphere, it cannot be dispersed because it does not rain there, and it stays there for years.

‘Banning nuclear weapons is the only long-term solution’

Since the end of the Cold War, the number of nuclear weapons has decreased, but the number of countries possessing nuclear weapons has increased. China is also estimated to be planning to quadruple its arsenal to over 1,000 nuclear weapons by the end of the decade.

“All nuclear-armed states are expanding or modernising their arsenals, and most are also intensifying their nuclear rhetoric and the role of nuclear weapons in their military strategies”, writes the Stockholm International Peace Research Institute.

– When nuclear weapons exist, they can be used, and the world has come close to nuclear war several times. Banning nuclear weapons is the only long-term solution, says Robock, adding that the nine nuclear-armed countries need to listen to science and the rest of the world.

Seth Baum, executive director of the US think-tank Global Catastrophic Risk Institute, calls the climate models ‘excellent’, but says there are many factors and uncertainties in exactly how humanity would respond to a global catastrophe of this magnitude, making the estimated death toll in the various scenarios difficult to assess

Martin Goliath, a nuclear weapons researcher at the Swedish Defence Research Agency, calls the study ‘interesting’ but says that the amount of soot formation is uncertain and that several of the scenarios are unlikely.