What happens if nuclear weapons are used?

Nuclear weapons are the most destructive, inhumane and indiscriminate weapons ever created. Both in the scale of the devastation they cause, and in their uniquely persistent, spreading, genetically damaging radioactive fallout, they are unlike any other weapons. A single nuclear bomb detonated over a large city could kill millions of people. The use of tens or hundreds of nuclear bombs would disrupt the global climate, causing widespread famine.

If a nuclear weapon detonates, what happens?

Short-term effects

A single nuclear weapon can destroy a city and kill most of its people. Several nuclear explosions over modern cities would kill tens of millions of people. Casualties from a major nuclear war between the US and Russia would reach hundreds of millions.

It takes around 10 seconds for the fireball from a nuclear explosion to reach its maximum size. A nuclear explosion releases vast amounts of energy in the form of blast, heat and radiation. An enormous shockwave reaches speeds of many hundreds of kilometres an hour. The blast kills people close to ground zero, and causes lung injuries, ear damage and internal bleeding further away. People sustain injuries from collapsing buildings and flying objects. Thermal radiation is so intense that almost everything close to ground zero is vaporized. The extreme heat causes severe burns and ignites fires over a large area, which coalesce into a giant firestorm. Even people in underground shelters face likely death due to a lack of oxygen and carbon monoxide poisoning.

Long-term effects

In the long-term, nuclear weapons produce ionizing radiation, which kills or sickens those exposed, contaminates the environment, and has long-term health consequences, including cancer and genetic damage. Their widespread use in atmospheric testing has caused grave long-term consequences. Physicians project that some 2.4 million people worldwide will eventually die from cancers due to atmospheric nuclear tests conducted between 1945 and 1980.

The use of less than one percent of the nuclear weapons in the world could disrupt the global climate and threaten as many as two billion people with starvation in a nuclear famine in the long-term. The detonation of thousands of nuclear weapons could result in a nuclear winter, which would destroy our fragile ecosystem. 

Physicians and first responders would be unable to work in devastated, radioactively contaminated areas. Even a single nuclear detonation in a modern city would strain existing disaster relief resources to the breaking point; a nuclear war would overwhelm any relief system we could build in advance. Displaced populations from a nuclear war will produce a refugee crisis that is orders of magnitude larger than any we have ever experienced.

Environmental and socio-economic impact of nuclear weapons

The existence of nuclear weapons has a strong impact on the environment. Nuclear war would mean a climate disruption with devastating consequences. The world would fall under a nuclear winter, be subject to a deadly global famine and exacerbated effects of global warming.

The socio-economic impacts would also be terrible, with developing countries and marginalized groups the ones that will suffer the most. Nuclear weapons are also a vacuum for financial support: in their development, maintenance and dismantlement. This is money that could be better spent funding assets such as green technologies and health facilities.

Learn more about how nuclear weapons affect the environment.

What makes nuclear weapons the worst