Atmospheric soot loadings from nuclear weapon detonation would cause disruptions to the Earth’s climate, limiting terrestrial and aquatic food production. Here, we use climate, crop and fishery models to estimate the impacts arising from six scenarios of stratospheric soot injection, predicting the total food calories available in each nation post-war after stored food is consumed. In quantifying impacts away from target areas, we demonstrate that soot injections larger than 5 Tg would lead to mass food shortages, and livestock and aquatic food production would be unable to compensate for reduced crop output, in almost all countries. Adaptation measures such as food waste reduction would have limited impact on increasing available calories. We estimate more than 2 billion people could die from nuclear war between India and Pakistan, and more than 5 billion could die from a war between the United States and Russia—underlining the importance of global cooperation in preventing nuclear war.

核武器爆炸产生的大气烟尘会破坏地球气候，限制陆地和水生食物的生产。在这里，我们使用气候、作物和渔业模型来估计平流层烟尘喷射的六种情景所产生的影响，预测战后每个国家在储存的食物被消耗后可用的总食物卡路里。在量化远离目标区域的影响时，我们证明，在几乎所有国家，大于 5 Tg 的烟尘喷射将导致大规模食物短缺，并且牲畜和水产食品生产将无法弥补作物产量的减少。减少食物浪费等适应措施对增加可用卡路里的影响有限。我们估计超过 20 亿人可能死于印度和巴基斯坦之间的核战争，