While it’s the middle of summer right now not many people are thinking about how to survive in cold weather. We are all to busy basking in the sunshine, swatting mosquitoes, and drinking beer at the camp or cottage to worry about the cold. But lets put things in perspective. There were 161 days last year where the temperature was below 0°C.

So what, you say. That leaves 204 days of above 0° temps right? Well it doesn’t take the temperature to be in the minus 20’s in order for someone to die from hypothermia. As a matter of fact most Hypothermia injuries occur at temperatures above the freezing level. All it takes is to head off unprepared.

Hypothermia is the lowering of the body core temperature. The bodies core is maintained right around 37°C. If it gets to hot, like when we have a fever, you get Hyperthermia. When it gets too cold you have Hypothermia. A swing of just 2 to 3 degrees up or down from the normal 37°C is enough to send one into hyper or hypothermia. Hypothermia’s symptoms are what’s known as insidious. They sneak up on you. It begins with your extremities getting cold. Fingers, toes, nose, ears all begin to tingle and get numb. The body shunting warm blood away from the extremities in order to keep the core warm causes this. In effect your body is beginning to shut down. At this stage your body core temperature is probably only down by about ½ to 1 degree from the normal 37°. You are in a stage called the “self help “stage.

The next stage of hypothermia is one where uncontrolled shivering begins. This is the stage where the body uses the muscles to try to generate heat by causing them to spasm. You can’t really control shivering but you can work through it. Body temperature has dropped by 2 degrees to around 35°C. You may find yourself becoming lethargic, have poor coordination and you may have nausea. You’re in the final stages of “self help”

Once shivering ceases you are in second stage hypothermia. The body has recognized that it cannot keep you warm by shivering so it stops trying. You may have violent cramping of muscles, severe coordination problems, incoherence, irrationality and confusion. Your body core temperature is down around 32°C right now. You are into the “buddy help” stage. If you are alone in the woods and have not sorted yourself out by this stage it will be extremely hard to do so. At this point, paradoxically, survivors have told of feelings of extreme warmth and wanting to disrobe. When the body core temp falls to 30°C sever rigidity and unconsciousness sets in. Death occurs at about 28°C.

As your body temp decreased you leave the “buddy help” stage and you go into the “medical help” stage. If you do not get into qualified medical help shortly then it may be too late. Even when late stage hypothermia victims reach medical help there is still a chance that it’s too late. The re-warming process sometimes causes a rush of super cooled blood to go from the extremities to the core causing even further cooling of the core and may cause cardiac arrest. If you come across a hypothermia victim do not rewarm them too quickly as this may happen to them.

There are many things out there that can exacerbate you getting hypothermia. The weather will help speed up heat loss. Improper clothing, getting wet, injury, and lack of tools to build a fire will all speed up this process but the most important things to remember is how the body loses and retains heat.

The body loses heat in 5 major ways: Radiation, Convection, Conduction, Respiration and Evaporation.

Radiation is the fact that as warm-blooded animals we are losing heat at all times when the temperature around us is lower than our body temperature. And in Nova Scotia there aren’t many days per year when the temp is over 37°C.

Convection is the air that moves around us cooling us off. As an example, when the wind is biting cold we put it at our backs it feels warmer on your front that your back. The cold wind is removing heat from your back through convection.

Conduction is when we touch something of a lower temperature than us the cold in that object transmits into our body by pulling heat towards the cold object. As much as we try we will never heat up that rock we are sitting on, it will only serve to suck all the heat from our body.

Respiration speaks for itself. The body takes in cool air and has to warm it before its exhaled.

Evaporation is the loss of heat when water or other liquids on the bodies’ surface are turned into vapor.

The body will try to prevent heat loss involuntarily through decreasing perspiration, shutting down blood flow to the extremities, and thickening of the skin (goose bumps). The body will also try to produce heat in an involuntary manner through shivering.

We can help the body to gain heat by doing semi conscious activity like stomping feet, swinging our arms, and wiggling fingers and toes. We can help prevent more heat loss by voluntary means like physical activity, and eating. We can also help ourselves prevent more heat loss by adding layers of clothing and seeking shelter from the cooling mechanisms.

When considering clothing for your trip into the bush think of it this way: you should dress for the environment, Dress in layers using non-restricting clothing.

The first layer should fit snugly to the body, but not restrict movement. It should have some warmth and have the ability to wick moisture away from the skin before it evaporates. Some of the best fibers for this are polyester, polypropylene or chlorofiber, as these fibers retain almost no water. Do not wear cotton next to the skin as it retains almost 5 times it weight in water.

The middle layer is the heat retention layer, its worn loosely in order to trap air in a “dead air” space around the body. It’s also the layer that is used as the “thermostat” for your body. When you get warm, open or remove this layer. As you cool you can put this layer back on. The best fibers for this are Wool, Fleece or polyester synthetics. Down also is used as a middle layer but beware of Down. If it becomes wet as it quickly looses its heat retention properties.

The outer layer is your wind and water protection. It is used to prevent you from getting wet from the outside while also protecting you from Convection heat loss. This garment should be breathable and may be worn loosely. Nylon is the usually the primary material used and to increase its breathability it might be laminated to membranes like Gore-Tex.

Do not forget the extremities when dressing. 70% of heat loss goes out the body from your neck up. Wear a hat or toque along with a scarf as required. When considering your hands dress in the same manner as above, using the layering principal. Keep your gloves loose on your hands so you have a dead air space to trap heat in.

If you remember to keep your clothing clean, avoid overheating, wear your clothing loosely and in layers, Keep your clothing dry, examine it regularly and repair as required then you will have no problem beating hypothermia.

Remember to always be prepared when you enter the woods.

Have a small survival kit with you.

Use the layering principle

Protect yourself from the wind

Avoid getting wet. (Including excessive sweating)

Avoid contact with cold substances

Avoid excessive respiratory heat loss

Avoid alcohol & nicotine

Use proper clothing for the environment

By Gary Micklethwaite / NovaScotiaHunting.com Field Editor