Scientists analysed six possible scenarios involving nuclear-armed countries that have the firepower to trigger worldwide suffering and deaths. They found that besides deaths from the atomic exposions themselves, such conflicts would also impact the global climate and famine.
These grim findings come at a time when the threat of a full-blown nuclear war is greater than at any time since the Cold War, with open conflict in Europe between Ukraine and Russia, and mounting tensions between the US and Russia as well as the US and China.
Scientists considered a hypothetical situation where a war broke out between India and Pakistan, and both targetted urban centres in the opposing coutry with 250 100-kiloton nuclear weapons. Such a scenario would kill 127 million people in South Asia alone due to explosions, fires and radiation, the study by researchers at Rutgers University found.
A full-scale war between the US and Russia – the worst-case scenario – would wipe out well over half of humanity.
“It’s really a cautionary tale that any use of nuclear weapons could be a catastrophe for the world,” said climate scientist and study author Alan Robock, a distinguished professor in Rutgers’ Department of Environmental Sciences.
Such conflicts would slash crop yields around the world because nuclear weapons would trigger firestorms that release sun-blocking soot into the atmosphere, researchers found.
The latest study marks the first time scientists have calculated the extent of deaths from famine and sunlight-blocking soot in the atmosphere, which are far greater than immediate casualties caused by atomic blasts.
A nuclear war between India and Pakistan, perhaps over the decades-long dispute over the Kashmir region, would release an estimated 37 million tonnes of soot into the atmosphere, causing temperatures across the planet to plunge by more than 5C – down to figures last experienced during the Ice Age.
It would also obliterate the production of major crops and fisheries by up to 42 per cent. Famine would kill two billion people across the world, the study showed.
A bigger war between Russia and the US, the powers that hold more than 90 per cent of the world’s nuclear stockpile, would kill an estimated five billion people.
However, any of the other nine nuclear-armed nations, including China, North Korea, France, Israel and Britain, have enough destructive capacity at their fingertips to cause immense worldwide suffering and deaths, sending soot covering the skies, triggering cooling and famine, the study noted.
The disruption of the global food supply in even a small-scale scenario would decrease global average caloric production by 7 per cent within five years of the conflict, marking the largest anomaly ever recorded, it said.
The study used “state-of-the-art climate, crop, and fishery models” to calculate how the availability of food could change in the world under various nuclear war scenarios.
It comes months after UN secretary-general Antonio Guterres warned that “the prospect of nuclear conflict, once unthinkable, is now back within the realm of possibility”.