Original title: Impacts of Nuclear War on Human Health from Changed Surface Ultraviolet Radiation
Shu Xu, Lili Xia, Alan Robock, Charles Bardeen +3 · August 2026
A nuclear war would send massive amounts of soot high into the atmosphere. This soot creates two competing effects: it damages the protective ozone layer, which lets more ultraviolet, or UV, rays reach the ground, but thick soot clouds can also block those rays. Researchers used climate models to see how these changes affect human health. In a regional war injecting 5 Tg of soot, ozone loss dominates. This boosts surface UV rays and drastically cuts safe outdoor time, hitting fair-skinned people hardest. It leads to roughly 5,300-9,800 extra skin cancer deaths within 10-15 years, and up to 75,000 extra deaths across the century. However, a massive 150 Tg war creates so much soot that it initially blocks UV light. This leads to around 8,500 fewer skin cancer deaths within 15 years. Extra UV also threatens crops and wildlife, creating a lasting hazard alongside famine.
Imagine you are deciding how long to stay outside on a sunny day. Normally, you check the UV forecast once and plan accordingly. But now suppose the UV level changes depending on whether you wear sunscreen or not, and also on how many clouds are in the sky. In this paper, after a nuclear war, the UV level at the surface is determined by two competing effects: soot in the air blocks some UV, but damage to the ozone layer lets more UV through. Depending on which effect is stronger, you might get more or less UV than usual, affecting skin cancer risk.
Nuclear war is already catastrophic, but this research shows an additional long-term health threat from increased UV radiation. Even a regional conflict could cause tens of thousands of skin cancer deaths over decades. This matters because it highlights that the health consequences of nuclear war extend far beyond the immediate blast and radiation, affecting survivors and future generations.
This study does not account for deaths from the war itself or famine, so the total mortality is much higher. It only considers skin cancer, not other UV-related health effects. The impacts on animals and plants, including agriculture, are not quantified. The scenarios are specific and may not cover all possible nuclear war sizes. The UV changes are based on climate model simulations, which have uncertainties.
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Impacts of Nuclear War on Human Health from Changed Surface Ultraviolet Radiation — Shu Xu, Lili Xia, Alan Robock et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.