Nuclear Winter: Definition & Theory

Instructor: Amanda Robb

Amanda has taught high school Biology & Physics for 8 years. She received her M.Ed. from Simmon's College and M.S. from Tufts in Cellular and Molecular Physiology.

In this lesson, we'll explore the concept of nuclear winter, and examine some of the environmental and societal catastrophes that would occur under such a scenario.

What Is Nuclear Winter?

Imagine a world filled with frost and ice-cold wind. The landscape has shifted from lush forests, teeming with life, to a charred terrain, with only the remnants of trees remaining. Animal carcasses have been incinerated. In the cities, cars are torched and buildings have crumbled. There are few traces of human society, such as gas masks littering abandoned buildings.

In a nuclear future, civilization lies abandoned.
chernobyl gas mask

Although this may sound like a scene from an apocalyptic movie, this is what scientists predict a nuclear winter would look like. Nuclear winter is an extreme theoretical climate change that would result from nuclear war. Although this hasn't happened yet, there is some important evidence predicting what the bleak results of a full on nuclear war would look like.

The consequences of intense fire, heat and blast damage, and radiation have been known to scientists since the development of nuclear weapons. However, it was only in the 1970's that scientists began exploring the drastic climate changes that would result from nuclear war. Through these studies, scientists realized that the effects would be long lasting. Frost and famine would eventually wipe out billions of people that were nowhere near the blast site.

Climate Change

First, there would be a devastating drop in temperature from the dust released during the explosions. It would rise into the atmosphere, carried by winds, and create a belt around the globe. The dust would block out the sun, our source of heat. As a result global temperatures would drop drastically. Also, fuel, plastics and other harmful chemicals in the cities would be ignited by the explosions and fire storms, releasing toxic chemicals into the air. All of these different chemicals could damage the ozone layer, which shields us from the sun's harmful radiation.

Winds carrying these chemicals would affect the entire globe, not just the targeted area. The result of these chemical and dust clouds would be a drastic cooling of the Earth. A recent study suggested that even in summer months, temperatures in North America could drop by 34 degrees Fahrenheit every year, for as long as a decade.

The debris and radiation poisoning from the atomic bomb dropped on Nagasaki caused massive destruction.
nuclear explosion

Food Sources

The drastic temperature change, along with the high levels of radioactivity and fire, would devastate any agricultural production. Grains, vegetables and farm animals, as well as natural forests, would cease to exist. The poisons released from burning chemicals, radiation levels, and climate change would make most of the earth inhospitable to crops and livestock. Our oceans would also be poisoned with radioactivity, and fish would no longer be edible.

Forests would look as if they had suffered severe acid rain, crumbling under the radioactivity and fire.
dying trees


Civilization across the world would cease to exist. Trains, buses, airports and roads in major cities would be destroyed by the blast and its after-effects. There would be little transportation throughout the country, and people would need to rely on local food and water sources, instead of the cross-country food sources available now. Infrastructure would also be wiped out. Local government buildings would crumble under the explosions. Healthcare and hospitals would no longer be available, and disease would eventually wipe out human settlements. There would be no more water treatment facilities to produce clean water, or power plants for electricity, leaving the cities in cold darkness.

An abandoned hospital corridor destroyed in a nuclear explosion.
hospital corridor

In the scenario of nuclear war, only 300 missiles targeted on American cities are necessary to produce this scenario. However, nine nations possess nuclear warheads, and the total number of warheads is estimated to be over 16,000.

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