Since Donald Trump was elected President of the United States, late night comedians, liberals, and forward thinkers have warned us against an upcoming nuclear winter. Some speculate that the nuclear winter will stem from the use of nuclear weapons, especially since other world powers still maintain extensive arsenals. As certain political figures continue to anger other world leaders, there seems to be a growing reason for concern.

Many people throw out this idea of nuclear winter but understand very little about how it would impact them and their families. It’s a term thrown around like it’s this only hypothetical scary thing that can happen in your nightmares. Quite frankly, we should be concerned with nuclear winter since it could actually happen.

But what does nuclear winter really mean and what can you expect if it does happen? Scientists, historians, and researchers have some ideas of what’s in store based on past events, such as volcanic winters and what happens after an atomic bomb is used. Here are 20 shocking facts about nuclear winter you should know about before anything too scary happens.

20. It Can Be Caused By More Than Just Nuclear Weapons

Some people have the misconception that only nuclear weapons can start a nuclear winter. This isn’t the case. A nuclear winter refers to the devastating global climatic cooling effect that could happen after a number of firestorms inject soot directly into the stratosphere. It would cool the earth to the point where crops would fail and it would be too cold for a lot of things to happen. However, a nuclear winter doesn’t require a nuclear weapon to happen. Technically, anything with enough scale to drastically reduce temperatures this way would count, such as a lot of severe volcanic activity or other types of fires on a massive scale.

19. 100 Firestorms Could Cause It

When you think of something as drastic as a nuclear winter, you’d think that you’d need a ton of firestorms to cause it. However, scientists and other researchers hypothesize that it would only take around 100 firestorms to cause a devastating nuclear winter. Think about it another way. If each state in the United States, with the exception of Washington, D.C. and U.S. territories had a firestorm, that would be enough. Or perhaps half of the recognized 196 countries in the world had one firestorm, it would also cause a nuclear winter. 100 is a relatively small number when you consider such destruction.

18. Wildfires Can Create Similar Effects

The next time you hear about a wildfire on the radio, you might want to listen. Scientists have found that wildfires can produce similar effects to those needed to create the conditions of a nuclear winter. If there are enough wildfires started because of arsonists, dryer than normal weather conditions, or a lack of funding to firefighting departments, this could be what leads up to an actual nuclear winter. Smokey the Bear might be more convincing in his campaign to stop wildfires if he explained that one of the very real consequences could be the start of a nuclear winter.

17. A Small Nuclear War Could Have Decades Of Impact

In 2006, the American Geophysical Union discovered that even a localized and small nuclear war could negatively impact the earth’s climate for 10 years or longer. This would cause a cooling effect that would make growing crops difficult and the air quality quite poor. Without food supplies, humans would not have access to the food that they need to survive. This would have worse consequences than a major drought. The 2006 study assumed that 50 Hiroshima sized nuclear weapons would be enough to trigger a nuclear winter. However, the size of the nuclear bombs have increased. It would possibly take even fewer nuclear bombs to create devastation that lasts decades or longer.

16. It Causes Massive Ozone Problems

Many people are already concerned with the depletion of the ozone layer and the impacts of climate change. But a nuclear winter would damage the ozone and cause even more issues for the climate than global warming in a fast and immediate way. A nuclear winter would create a near worldwide hole in the ozone layer that would impair human health and cause long lasting environmental damage. The ozone problems would start after the soot is released into the atmosphere. The soot absorbs the solar radiation to heat atmospheric gases, which would lead to destruction of the stratospheric layer of the ozone layer.

15. It’s Followed By Nuclear Summer

Nuclear winter is not the only problem with nuclear winter. The nuclear summer that follows it would be just as troublesome. When the Earth begins to heal and the debris finally falls from the atmosphere, the survivors will have to deal with the damage that the nuclear winter caused. Mainly the ozone damage which will increase the temperatures substantially. Anything that adapted to survive lower temperatures will need to adapt again to survive higher temperatures that would normally kill things before the nuclear winter. So any gains that we make in replacing crops and water sources may be undone by another hard shift in temperatures.

14. The Loss of Other Species

Nuclear winter would result in a major extinction event for most species of plants and animals. The darkening effect that nuclear winter creates would block sunlight for plants. This would starve them as they wouldn’t be able to photosynthesize anymore. The animals that rely on these plants for oxygen creation and food would also starve. Humans would likely starve to a large extent because of the loss of animal and plant-based food sources. Unless we can invent a synthetic food source or find a way to grow food without sunlight, the loss of food sources would be a major issue.

13. Running Out of Oxygen

As the wide range of carbon dioxide breathing plants begins to die off from a lack of sunlight, the amount of carbon dioxide in the air will increase. The remaining people and animals will contribute to an increasing amount of CO2 without an effective way of replenishing the amount of oxygen in the world. True, there is technology to circulate oxygen and remove carbon dioxide from the air that we breathe, but not on a global level. So, unless we invent terraforming technology, we will likely have an major oxygen shortage on a global scale that we’ve never seen before.

12. Light Shortages

While it may not be immediately obvious, the resulting light shortage is a bigger problem for people than you may think. Aside from the effect on the food sources that we rely on, not having normal sunlight is a major health concern for human. Sunlight causes the absorption and production of vitamin D which humans need to stay healthy. Going out in the sun is how we get a big amount of our vitamin D. Unfortunately, the dust clouds in a nuclear winter will decrease the amount of light at the brightest point of the day by up to 66%. To survive, we will need a new source of vitamin D. We will also need to adjust to living in a darker climate which is not always good for our eyes wither.

11. Water Shortages

In a nuclear winter, one of the biggest problems for survival would be water shortages. At first, the amount of rainfall would help. The rain would catch some of the soot and force it out of the atmosphere as it rained. However, the increasing amount of soot would result in nearly 75% less rain overall as UV rays and colder temperatures would stop the rain from evaporating and accumulating. Without natural rainfall, most areas on the planet that rely on rain to replenish fresh water resources would begin to dry up. Naturally, this would make survival difficult as only areas with the ability to purify saltwater would avoid the worst of the water shortage. Unfortunately, processing plants would be in short supply, and even the ones that exist would struggle to keep up with the demand.

10. TTAPS Predicted How It Works

A group referred to as TTAPS wrote a paper in 1990 that outlined how a nuclear winter would work. Since there is no evidence of a nuclear winter occurring during the records of human history, much of what we know about nuclear winters is theoretical. Despite that, many people believe that TTAPS’ predictions could be strikingly accurate which gives us a framework to develop prevention and recovery methods. Prevention is by far the best option that we have to avoiding a nuclear winter. Not only can humans avoid being the cause, we have the ability to try to address natural causes when they occur. In short, we can control nuclear winters given the right amount of resources and effort.

9. July Is The Worst Month For Nuclear Winters

The worst start time for a nuclear winter is actually in July. July is usually the hottest part of the year. After July, temperatures naturally drop around the world. Because of this, a nuclear winter beginning in July would cause temperatures to drop much farther than they normally would. The decrease would be enough for water to begin freezing in more areas, and crops that normally grow in hotter parts of the world to begin failing. All of this would lead to some of the worst possible outcomes and make surviving a nuclear winter significantly harder.

8. Hats, Sunglasses And Sunscreen Become Mandatory

In a nuclear winter, the days of going outside without sun protection would be over. The increased amount of UV rays would cause skin and eye damage at an alarming rate. Your eyes could be heavily damaged by UV radiation without you ever realizing it until you have problems with your sight. Every time you went out, you would need skin protection like hats, sunglasses, sunscreen and long clothing. The days of short shorts and no sleeves would be over. Your skin would not be able to handle the sunlight without significant protection. If you didn’t use protection, the chances of getting skin cancer go through the roof.

7. Society Would Have Serious Problems

Another somewhat overlooked but seemingly obvious problem in a nuclear winter is the breakdown of society. Social structures would begin to break down as people fight over food, water, and other essentials. Currency would likely become useless as well making it harder to trade for things that you need. As society begins to crumble, looting, rioting, and other potentially violent events could increase, making cities a more dangerous place. If you’re focused on survival, you may be safest in rural areas where you can produce your own supplies in abundance as well as protect yourself, your supplies, and your family.

6. It May Have Happened Before

While there is no evidence to suggest that a nuclear winter occurred in the fossil records, a similar event may have already happened. The K-T Boundary Extinction Event that killed the dinosaurs is believed to be an impact winter, the result of an asteroid slamming into the Earth. The method of releasing the debris into atmosphere was different, but scientists believe that the results are much the same as a nuclear winter. This also leads many scientist to believe that it could result in another global ice age and population decrease if a nuclear winter ever did happen.

5. People Caused A Small One In 1991

The Persian Gulf War saw the end of President Saddam Hussein’s (Iraq) reign. Before he left, he cause a miniature nuclear winter in Iraq without ever using a nuclear weapon. Instead, he used Iraq’s most valuable resource: oil. Iraq is the home of many of the world’s most prominent oilfields. To prevent UN and US forces from getting the resources from the oilfields as the Iraqi army retreated, Hussein ordered that the oil wells be set on fire. This created huge smoke clouds that had the same effect as a nuclear winter. Temperatures in the area began to drop and the effects were felt long after the fires were put out.

4. Levels Of Nuclear Winter

Scientists that study the possibility and possible effects of a nuclear winter defined several levels to describe the different types of effects. There are six levels in total ranging from a minimal nuclear winter to an extreme nuclear winter. Each level is an order of magnitude worse than the one before. While the lowest level of a nuclear winter can have no effects on the global climate, the immediate area would suffer greatly. By the third level, the effects are global and far reaching. Few people may escape the overall problems that a nuclear winter would bring and nearly all of the planet’s population (animal and plants alike) would be affected.

3. The Southern Hemisphere May Be Safer

One interesting fact is that the location of the cause of the nuclear winter is important. Many of the different theories about a nuclear winter, even the ones that don’t focus on the use of nuclear weapons, have the same thing in common. Nearly all of them believe that the source is in the northern hemisphere. Most of the world’s population lives at or above the equator, so this is a plausible idea. Furthermore, major changes to the climate system in the northern hemisphere may have a smaller change on the southern hemisphere as this system changes at the equator. It could serve as a natural barrier that makes the southern hemisphere less affected and giving mankind a somewhat safer place to retreat to.

2. Computers Cannot Predict The Effects

Predicting the weather is exceedingly difficult. Our planet’s atmosphere is extremely complex and this makes it nearly impossible to predict its movements with any semblance of accuracy. This is made even more apparent when you factor in a major change like adding thousands or millions of tons of debris to it. Even with the most advanced computer modeling software, scientists can only predict several days worth of standard weather patterns, and they are often not as accurate as some would think. Because of this, preparing for a nuclear winter is difficult since we have no idea how it will turn out and how the global climate will accurately change.

1. TTAPS Helped Prevent One

In the 1970s and 80s, Russia and the United States were getting into a consistent conflict that threatened to involve nuclear weapons. Each country had, and still has, thousands of nuclear weapons ready to be fired at a moment’s notice. If they had, it would be more than enough for a nuclear winter. What’s worse is that they were close to using them. Then, TTAPS released its first report in 1983 which outlined the effects of a possible nuclear winter. Many people think that this report help get Russian and the U.S. to back down a bit from using nukes. Both countries reviewed the report and took it seriously which is why many think it helped avert a nuclear winter.