This article on surviving extreme cold is part of the Science in Sci-fi, Fact in Fantasy blog series. Each week, we tackle medical or technical aspects of science fiction or a historical / world-building topic of fantasy with input from an expert. Please join the mailing list to be notified every time new content is posted.
The Expert: Gideon P. Smith
Gideon P. Smith, MD PhD MPH is a physician-scientist. In an earlier career, he was a geophysicist. In fact, that is what the PhD is in. He spent several seasons working in Antarctica, planting seismometers while tracking whales with the marine biologists on board research cruises in the Drake Passage. He has published over 100 first and senior-author papers in scientific journals including in top-tier journals such as Science. In his spare time, he writes science fiction and epic fantasy and has written for the Science Fiction and Fantasy Writers Association and Black Hare Press. You should check out his blog and maybe follow him on Twitter.
Common Misconceptions About Surviving Extreme Cold
In part 1 of this three-part article, we dealt with the social and evolutionary aspects of cold environments. In this second part, we will touch on the physics of it. We will look at survival in cold environments when suddenly thrown into them.
And we will again look at how these things are often misrepresented in science fiction, and how we might go about getting it right. But first, in order to understand what is wrong in science fiction with the way cold survival is portrayed, we need to understand some facts about cold, and how it affects us. And we also need to bust some of the common myths that trip writers up.
Myth 1: Temperature and cold are the same thing
Fact 1: Humans can actually be in a -454F environment and not only survive, they may not even be ‘cold’
We’ll loop back to the above hard-to-believe fact at the end of this article, but before we get to that, we need to recall some basic physics.
To start, some basic definitions. Temperature is a measurable, quantifiable physical parameter. Cold is a sensation. When my house is 68F I feel unacceptably hot. My family feels this is cold and move the thermostat up to 76F.
Whether you feel cold or not is a combination of 4 factors:
- The actual temperature,
- The rate at which heat is transferred away,
- Your intrinsic metabolism and biologic homeostasis aimed at heat conservation, and
- Your brain.
Two of these are about you, two of these are about your environment.
In this article, we are focused on the environment, and for that, we need to go back to high school physics. Heat is transferred from one place to another by one of three mechanisms: conduction, convection, or radiation.
Heat Conduction, Convection, and Radiation
Conduction is when the substance does not move, but simply transfers the kinetic energy from the heat source, down the heat gradient away from the source. The simplest everyday example is putting a spoon in coffee. Eventually, the spoon handle, which is not in the coffee, will become hot as the heat is conducted along the metal handle.
Convection is where the heat source transfers kinetic energy to something (usually a fluid or gas) with which it is in contact, such as air, or water, and that ‘something’ then transports the heat away e.g. hot air rises and is replaced by cooler air.
Radiation does not require any medium to transport energy. Radiation can occur through the vacuum of space and is how ultraviolet, light, and heat from the sun reach the Earth.
Why is this important? Because it tells us how to survive extreme cold – by controlling these possible heat transfer mechanisms. If the environment is cold, our most valuable resource is our current body-heat. If we are trying to maintain heat, we can do little about radiation, but we can minimize conduction and convection.
The easiest thing to control is convection. Convection as we noted requires you to be in contact with a gas or liquid that is capable of flowing. That is why we dress in layers, not only to allow fine-tuning of temperature as we add or remove layers but because these trap layers of air, preventing convection, thereby retaining the heat.
The same principle applies to any survival shelter you construct. You have to prevent air exchange. In the modern day we do this with double glazing and front doors, but without these modern marvels, how should an ‘emergency’ shelter be constructed? You can just block the door but that prevents coming and going. A practical solution that requires no supplies is to build an entryway that slopes up. Why? Inside is air, hot air rises, and so this design traps the heated air inside.
What about conduction? Well, the walls must be built of something. Steel or aluminum crates may be ready-made, but have high conductivity and often make for cold shelters. Instead, you should create walls as thick as possible with low thermal conductivity. The igloo is a good example of this. Not only are the walls thick, but ice has low thermal conductivity, cutting back on this transfer. You may not even need to construct an igloo, if you dig down and create a survival shelter underground, and in an emergency situation, for one night caught out, this is what you would do. The downside of this is the entry is pointed up, and creates a chimney that allows all of your warm air to convect away. In this design, therefore, you have to block the exit, and ensure air circulation for breathing via some smaller route.
Examples of Problematic Extreme Cold/Exposure. in Science Fiction/Fantasy
Inefficient or ineffective heat conservation
I hate to pick on Star Wars, as I literally grew up on this stuff and it birthed my fascination with science fiction, but one of your most valuable resources in a cold emergency is conserving your body heat. Han could have conserved Luke’s by partially burying him in the snow, by cutting off tauntaun hide and throwing it over him, but one thing that was not wise was getting his layered clothing, which was trapping layers of warm air against his body, soaked through with tauntaun body fluids. It might have provided a small amount of heat temporarily but would have made his clothing completely ineffective in heat maintenance once he was pulled out. And dead animals don’t hold onto their heat long. We know this as this approach with horses was tried in real life in the US wild west, usually with poor outcomes. Maybe I could accept this if he had stripped him like Leonardo DiCaprio did in the Revenant, but even so, while that may conserve his clothes utility, it’s losing those trapped air layers which will have to be rebuilt. And for what? Exactly how long does a tent take to pitch in Star Wars? It can’t be longer than it does in our world now.
Ways to Get Cold Exposure Science Right in Fiction.
Thinking about what we learned above, how can you get the science right, and what might be some cool things to include in your science fiction?
So first, separate the concepts of snow and ice from cold. Ice does not form without moisture. If your heroes are trying to survive, make sure they keep their clothing dry and free of tauntaun guts, have them build a shelter that focuses on the key heat-conservation principles – stop convection with an upsloping entrance, make the walls from low thermal conductivity materials like ice, not metal, and trap the warm air while allowing cooler air exchange for breathing.
Finally, I promised at the beginning we would loop back to the scenario where humans can be in an extremely low-temperature environment and not only survive, they may not even be ‘cold’. I even quoted -454F. The reason I have left it till last is to give you the option not to read it, as it is such a common error in our genre it may ruin many genre works for you. If you don’t want to know, stop reading now.
-454F is the temperature of the vacuum of deep space. Many short stories, novels and movies make the mistake thinking that because the temperature is so low, you will freeze instantly. E.g. Mission to Mars, one of the characters takes off his spacesuit helmet and spontaneously turns to an icy corpse, sacrificing himself so his family won’t waste time trying to rescue him. Heroic. And complete nonsense.
I’m not saying he won’t die. But he’s most likely to die from lack of oxygen, and that’s going to take as long as a breath lasts. He’s no more likely to suddenly turn into a popsicle than he is to explode from the low pressure like Vilos Coohagen at the end of Total Recall. The reason is, in space, there is no air. And without that (remember that high school physics?) not only is there no breathing, but there is no conduction and no convection. So, despite the extreme temperature, he will only lose heat via radiation. Which is quite slow. He will get colder, but it will take hours. So kill your villains by asphyxia, but not from instantly freezing when exposed to the vacuum of space. And I will close by apologizing for having just ruined a whole host of sci-fi for you, because every time you see this, you will cringe now, just like I do.
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