Nuclear Winter - What does it mean?

With the recent events surprising quite a lot of us, anxiety about a third world war skyrocketed. Especially after the thread of a nuclear attack, everyone heard the term “nuclear winter”. What does this mean? Would it be the end of humanity?

After the thread of Putin that he would use nuclear weapons if a country decides to step into this war with Ukraine I started to hear the term “nuclear winter” quite often. Since I wasn’t sure what this means I started to investigate it a little bit.

What is a nuclear winter?

Because of the extreme destructive power of a nuclear bomb the climate will change if enough of the bombs will explode in a short enough time frame. Nuclear winter is the word for a such an event.

When such a bomb goes off it will burn everything in a certain area. Houses, cars, trees and everything else. This things will burn with such a high temperature that the soot will rise high up in the atmosphere. When enough of this soot accumulates there it will block enough direct sunlight so that the temperature here on the ground will drastically decrease. Some researchers are suggesting that the average temperature will decrease about 6 - 8 K or up to 20° in Europe US and China, depending on the numbers of nukes dropped.

When would a nuclear winter happen?

A nuclear winter doesn’t happen when “just one” bomb goes off. According to a study, if nukes with a combined power of 5000 megatons explode, thiw would make sure that a nuclear winter would happen. For comparison the bomb that exploded in Hiroshima, called “Little Boy”, had a power of 13 Kilotons. This is still normal for small nukes. But big Intercontinental Ballistic Missiles often have above one million megatons explosive force on its own, quite often they have about 10 MT. So, just a few of those and we would have a garanted nuclear winter.

What would it mean for humanity?

The decrease in temperature would course a massive famine because of the crop freezing and therefore dying. Because of the extended period this whole “winter” is taking this could go on for decades so a huge number of survivors of a nuclear war would most likely starve to death. Since many areas of the big crop growing regions would be hit especially hard this famine could be the worst famine ever.

Are there any chances that a nuclear war wouldn’t trigger a nuclear winter?

Well, it’s hard to say. There are some physicists who are rebuking the idea of a nuclear winter because they find the science lacking. Famously, William R. Cotton who supported this idea in the 1980’s reversed his position in a book published in 2007. In this book he is arguing that rain would wash out enough soot so that the consequences wouldn’t be this drastic.

Whatever it is, let’s hope that we don’t find out!