Ice Raven - Sub Zero Adventure - Partner site of Ravenlore Bushcraft and Wilderness Skills and Waylandscape. Arctic Exploration, Travel and Photography.
Ice Raven - Sub Zero Adventure - Partner site of Ravenlore Bushcraft and Wilderness Skills and Waylandscape. Arctic Exploration, Travel and Photography.
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Surviving in Extreme Cold.

By. Damian O’ Toole.

Woodsman Bushcraft.

As I sit here writing this article, December is well on its way and as I look out of my window I see the figures passing are bedecked in woolly hats gloves and scarves, and I smile and wonder how they would get on in the truly cold place of the earth. I have traveled quite extensively over the years from hot jungles to arid deserts, but even though England will always be my home, it is the Arctic North I miss the most..

The Arctic like many environments has a uniqueness not found anywhere else on earth and to me is one of the most beautiful, alluring, though certainly quite dangerous places to be, and like so many other extremes it punishes the unwary, the ill prepared, and the foolish harshly. In this article I hope to address the key issues with traveling and surviving in the frozen North (or South) and how you can safely enjoy, what is sadly becoming a shrinking environment.

How the Cold effects your body.

The human body is an amazing creation, I’ve seen it do unbelievable things and feats of endurance far beyond what I would have thought possible; However for all its ability to be tough and adaptable, the human body itself is very delicate. Just the smallest of changes can have the most adverse effects, and cause the hardiest of us to wilt and fall. The body require a fine balance of internal processes to work, and it's this fine balance that suffers the most in the extremes of temperature.

You’re internal organs need to exist in a very small temperature range of 37 Celsius (95F), this is know as your ‘core temperature, and only a small change in this temperature, either up or down and the rest of the body starts to experience problems. To help maintain this temperature warm blood is taken and circulated around the rest of the body, through thousands upon thousands of veins, arteries and blood vessels from the tips of your fingers to the ends of your toes, and used to maintain an even temperature throughout. Many of these paths bring the flow of blood very close to the surface of your skin, such as in your fingers, and toes, and more noticeable in places like your cheeks. when the internal body is hot the ‘arterioles’ which lie just under the skin dilate allowing warm blood to circulate under the skin. Sweat is released that cools through evaporation, and in turn cools the blood, which is returned to the core via the blood network and cools the core down, this is one of the reasons that hot people appear red, and sweat a lot. Alternatively when the core temperature starts to fall, then the arterioles contract to restrict the warm blood from coming into contact with the cold skin, then transferring the cool blood back to the bodies core. The body also has other mechanisms for dealing with the cold, as the surface of the skin cools small muscles at the base of the hairs called ‘arrectores pilorum’ contract causing the hairs on your body to stand erect. These tiny hairs then trap the warm air next to the surface of the skin in an attempt to reduce the loss of surface heat through convection.

Circulatory_System
capillaries

As the surface temperature of the skin drops, the cooled blood eventually finds its way to the deep organs causing the bodies core temperature to fall by a fraction of a degree. This tiny fall in the core temperature in the core, triggers the next stage of the bodies defense against the cold. The body starts to generate heat by contracting muscles rapidly, which exhibits itself as ‘shivering’ the fuel for this process is taken from the bodies fat reserves, Brown fat is converted to produce heat through the a process called Oxidative Phosphorylation (OXPHOS).

The body uses this system to generate heat deep within the muscle tissues in an attempt to maintain the bodies core temperature; Blood supply to the bodies extremities is also reduced and directed to the core to limit the loss of heat at the bodies external surface, this reduction of the blood, leaves the extremities particularly susceptible to cold damage (frost nip, and frost bite) as the new supply of heat is not enough to stop the skin from starting to freeze. Shivering will increase dramatically as the body tries desperately to generate heat in the deep organs.

Hypothermia

Mild (core temperature 37C-32C/ 98F-90F)

As the core temperature continues to drop the body starts going into the early stages of hypothermia the body shivers uncontrollably, and motive actions become impaired, hands and fingers will become painfully still and coordination will be noticeably reduced, as the core temperature drops below 35C the mind is starting to be effected with confusion and the feeling of apathy, slow speech and thought processes, with retrograde amnesia. difficulty in walking, and loss of use in hands and fingers, the body is now burning up fat stores at a rapid rate, and shivering resembles someone having a fit. an increase urge to urinate. As the core continues to cool.

Moderate (core temperature 32C-28C / 90F-82F)

Shivering start to subside then stop as the body can no longer maintain the energy to continue, the joints become stiff and the body can no-longer support itself to walk or stand, confusion extends into incoherence, with bouts of irrationality, the pupil of the eyes start to dilate and breathing becomes shallow and indistinct, before finally lapsing into semi consciousness, the heart starts to beat more slowly, and becomes harder to detect.

Severe (core temperature below 28C/82F)

Breathing and heart rate are now difficult to detect, the body falls into full unconsciousness, as the body has no reserve left to keep basic function alive, the skin takes on a pallid tone, blood is no longer providing oxygen to the main organs and body starts to shut down until at around 25C and below, the heart stops beating and shortly afterward followed by death....

Preventing the above

To remain safe and reduce the possibilities of cold based problems, First the individual needs to understand the mechanisms involved in the loss of heat from the body. Secondly how to address these factors, and thirdly how to minimise the exposure of the body to environmental factors. So firstly lets look at the main four factors that are responsible for temperature loss.

Radiation

Evaporation

Convection

Conduction

Radiation

Our bodies radiate heat, most of which is in the form of infra-red radiating from our warm bodies and is our biggest form of heat output, and our largest form of heat loss. The heat is exchanged directly with the surrounding area, and the colder the area the greater the heat loss. Radiative heat loss is also the hardest to protect against as clothing does not stop this form of heat loss, as your body heats the material which in turn is exposed to the environment and is lost to the outside world. Clothes do however reduce the amount of heat loss through radiative heat loss, and especially layered clothes, as these produce micro-climates between the layers and because the layers are very close in temperature to each other, the amount of thermal transfer is less than it would be on a single layered garment. Heat is still lost through the outer layers, but this is now in much smaller quantities which, in a healthy body can easily be replaced through normal bodily processes. The best form of protection from radiative heat loss is to provide protection from the environment itself, or limit the amount of exposure This can only be done through the creation of a shelter which can be heated to create an enclosed area that limits the differences in skin temperature and the air contained within. The science behind this in basic terms says that a hot body will radiant heat in an environment that is colder than itself, and absorb heat in an environment that is warmer than itself; The greater the differences in temperature the greater the rate at which the temperature is either radiated or absorbed.

Human-Thermal Image

The human body will start to radiate heat to its surroundings when the surface of he body is exposed to temperatures less than 28C/82F this is the temperature when a naked body is said to be in a state of thermo-neutrality, the body neither looses heat to the environment or gains heat. The addition of clothes to the equation lowers the radiative effect and means that depending on the materials used in the clothes, and the thermal properties of these; that a body at rest in an environment slightly below the 28C mark can easily produce enough heat through normal bodily heat generation to be in a comfortable thermal state.

In temperatures higher than the thermoneutral point then the body starts to absorb heat, and this is just as dangerous as heat loss, however this I intend to cover in a different article on extreme heat environments.

Evaporation

The human body is mainly water, about 50-65%, in fact; it is essential for our survival, and almost everything our bodies do, relies somewhat in the water our bodies crave. To maintain a healthy working body, fluid lost during the operations of the body needs to be replaced, these operation are things such as waste, digestion, and breathing. In extreme cold climates the moisture normally found in the air (relative humidity) has become frozen and removed from the area in a form that our bodies can use. Every time we breath the incoming air needs to be both warmed to body temperature and hydrated to 100% humidity, as we breathe out this warm hydrated air is lost to the surrounding environment, and the process repeats. This process of warming and hydration accounts for approximately 20-30% of the heat lost from the body. Two thirds of this is lost at the surface of the skin, not from radiation, but by the natural release of minute amounts of perspiration, that occurs even in very cold climates. effective and practical systems to reduce this have little or no effect at extreme low temperature,  membrane systems quickly become blocked as the tiny moisture particles freeze instantly on contact with the freezing air so really nothing can be done to limit this lost of bodily heat and attempts in the past to produce successful barriers that can be used have largely met with little success, usually leading to producing effects that cause even more problems due to saturation of clothing as a result. The best way to deal with this is not through prevention but simply through acceptance. The body will and needs to hydrate and warm the air coming into the body, and this warm wet air needs to be exhaled, as a result the body does loose heat and moisture, which needs to be replaced. So in simple terms, you need to replace the fluid you lose by drinking and provide the body with energy it can convert into heat by eating. With the perspiration the best system is to frequently change items like socks, and applications like antiperspirants and talc in areas where moisture tends to collect.

Convection

The air directly above the skin (usually only 1-2mm at maximum), is warmed to the same temperature as the skin by means of thermal radiative heating. If the body were for instance put inside a sealed box, thats walls were thermally inert. Then eventually the air inside the box would be heated to the same temperature as the body within until they are both in thermal balance or no-longer exchanging heat in any direction. However if we were to then replace that warm air with cool outside air then the process begins again, and so forth. In convention the heated air just at the surface of the skin is replaced by cooler air moving across the skins surface, which increases the difference in temperature and causes the skin to radiate more heat to repeat the process, this is why wind speeds play a vital role in the way environmental temperature effects how we experience the temperature. For instance if you were to stand outside on a winters day and the temperature was 0C with no air movement at all. Your body would react to the temperature of 0C because thats the temperature that it is currently feeling. If however we then increased the wind movement from 0-5Kph (3.1mph), event though the ambient temperature has not changed, its still 0C, the cooling effect the wind has through convection and dispersion makes us feel that the temperature has now dropped to -2C, as the warmed surface air around our bodies is being constantly removed and replaced with cool air. The following chart gives an example of how our feeling of temperature changes with airspeed.

Temperature C (F)

 

0 (32)

-5(23)

-10(14)

-15(5)

-20(-4)

-25(-13)

-30(-22)

-35(31)

-40(-40)

-45(-49)

-50(-58)

Wind speed (kph)

What temperature we feel

5

-2(28)

-7(19)

-13(9)

-19(-2)

-24(-11)

-30(-22)

-36(-33)

-41(-42)

-47(-53)

-53(-63)

-58(-72)

10

-3(27)

-9(16)

-15(5)

-21(-6)

-27(-17)

-33(-27)

-39(-38)

-45(-49)

-51(-60)

-57(-71)

-63(-81)

15

-4(25)

-11(12)

-17(1)

-23(-9)

-29(-20)

-35(31)

-41(-42)

-48(-54)

-54(-65)

-60(-76)

-66(-87)

20

-5(23)

-12(10)

-18(0)

-24(-11)

-30(-22)

-37(-35)

-43(-45)

-49(-56)

-56(-69)

-62(-80)

-68(-90)

25

-6(21)

-12(10)

-19(-2)

-25(-13)

-32(-26)

-38(-36)

-44(-47)

-51(-60)

-57(-71)

-64(-83)

-70(-94)

30

-6(21)

-13(9)

-20(-4)

-26(-15)

-33(-27)

-39(-38)

-46(-51)

-52(-62)

-59(-74)

-65(-85)

-72(-98)

35

-7(19)

-14(7)

-20(-4)

-27(-17)

-33(-27)

-40(-40)

-47(-53)

-53(-63)

-60(-76)

-66(-87)

-73(-99)

40

-7(19)

-14(7)

-21(-6)

-27(-17)

-34(-29)

-41(-42)

-48(-54)

-54(-65)

-61(-78)

-68(-90)

-74(-101)

45

-8(18)

-15(5)

-21(-6)

-28(-18)

-35(31)

-42(-44)

-48(-54)

-55(-67)

-62(-80)

-69(-92)

-75(-103)

50

-8(18)

-15(5)

-22(-8)

-29(-20)

-35(31)

-42(-44)

-49(-56)

-56(-69)

-63(-81)

-69(-92)

-76(-105)

55

-8(18)

-15(5)

-22(-8)

-29(-20)

-36(-33)

-43(-45)

-50(-58)

-57(-71)

-63(-81)

-70(-94)

-77(107)

60

-9(16)

-16(3)

-23(-9)

-30(-22)

-36(-33)

-43(-45)

-50(-58)

-57(-71)

-64(-83)

-71(-96)

-78(-108)

65

-9(16)

-16(3)

-23(-9)

-30(-22)

-37(-35)

-44(-47)

-51(-60)

-58(-72)

-65(-85)

-72(-98)

-79(-110)

70

-9(16)

-16(3)

-23(-9)

-30(-22)

-37(-35)

-44(-47)

-51(-60)

-58(-72)

-65(-85)

-72(-98)

-80(-112)

75

-10(14)

-17(1)

-24(-11)

-31(-24)

-38(-36)

-45(-49)

-52(-62)

-59(-74)

-66(-87)

-73(-99)

-80(-112)

80

-10(14)

-17(1)

-24(-11)

-31(-24)

-38(-36)

-45(-49)

-52(-62)

-60(-76)

-67(-89)

-74(-101)

-81(-114)

Conduction

The main difference between convection heat loss and heat loss through conduction is that in convection heat is ‘replaced’ and then dispersed into the environment. In conduction heat is directly drawn from the body by direct contact with a conductive cold mass. As remarked above, the conductive process is bidirectional, in other words if the mass has a greater temperature than the body then heat is transferred to the body at the point of contact (if the point is very hot we get burnt!) The mass in question can either be a solid or a liquid, and the better the conductor the faster heat is transferred. In extreme cold environments understanding how heat is drawn from the body by different materials is very important. For instance if we take the air around us as having a conductive rate of 0, then place a body in water of equal temperature, the water will conduct heat from the body 25 times faster than the air. Sitting on Ice will increase the rate the body looses heat at the contact point by approximately. 85-90 times. Whereas sitting on wood the increase will only be 3-5 times as fast. Metals naturally conduct heat very well, and as such should be avoided contact with the body in extreme cold climates, as the rapid conduction of heat can quite literary fast freeze the skin to the surface of the metal. So the old story of not touching your wet tongue to a metal post is quite true, the water on your tongue is quite literary fast frozen in place, and of course the embarrassing questions by passers by and rescuers is always a good incentive not to give this one a go. When considering clothing and shelter materials. Items such as wool which has a relatively low conductive rate, should be considered against nylon which has a relatively high conductive level. Metal in shelters should be given extreme consideration as there high conductive rate will quickly remove valuable heat, whereas wooden shelters loose heat at a much lower rate.

boy_with_stuck_jpg

Health considerations before an Arctic trip.

Before any trip to areas that will be experiencing extreme cold, its always a good idea to look to your own physical health beforehand. Deep snow is very difficult to navigate through, even with the use of snowshoes, While no one is saying that you should be Olympic level fitness, you should however be physically fit enough to cope with the demands of the activities that you intend to engage in; Snow walking is physically extremely strenuous, and even relatively short distances can be tiring.

Poor circulation should be addressed before traveling in extreme cold. The extremities are the first place that the cold attacks and poor circulation in these areas can make an individual prone to cold damage like frostbite and frost nip. It doesn’t mean however that if you do suffer from poor circulation you can’t go, many people have this problem and have no problems at all, they do however take extra precautions with those areas of the body, such as hands and feet, and frequent checking is advised.

If you intend to engage in much wilderness travel, especially in remote destinations, spare a thought to the clothing you are wearing! An increasing number of adventurers, are adopting military clothing as their choice for the Arctic; this clothing while extremely hard wearing and of a high standard, is in fact designed with the soldier in mind and not civilians. Surplus Arctic equipment is usually coloured or patterned to hide the individual within the terrain, while this is excellent for a soldier, it’s not so convenient for a civilian lost in the wilds, and makes location by search and rescue personnel a lot more, and unnecessarily difficult. A person wearing white from head to toes against a white background is almost impossible to see from a search and rescue helicopter or search plane. Again this doesn’t  stop you wearing this kind of clothing, but you should have high contrast clothing such as a tabard that can be put over your Arctic whites should the need arrive.

And Finally.

Our Arctic areas, are sadly disappearing at an alarming rate, they contain some of the planets most wonderful sights and animals, many of which may not be around for our grandchildren to enjoy. So whenever you travel to these lands of ice and snow, be respectful to the environment and take out whatever you have taken in. Even on the High Arctic Peninsular I have come across the garbage of previous travellers.

But most of all, go there, see it, experience it, before it is gone.

Damian

 

Sub Zero Crew - Bushcraft UK
Arctic Expeditions, Equipment and Reviews Extreme Weather, Equipment and Reviews

Unless noted otherwise, all photography, artwork and content on this site is copyrighted. © Gary Waidson 2014 All rights reserved.

The Ice Raven Project promotes sustainable and low impact bushcraft and wilderness skills in Arctic and winter conditions. This includes the use of  tents, tarps  and snow shelters where possible. Fires are only used where safe and where use and collection of firewood will not damage the natural environment. We often travel to locations by public transport and then use snowshoes, sleds, toboggans and pulks to transport our equipment into the wilderness.

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