-all photography copyright David Pickford / www.davidpickford.com -
Revelling in the sunrise on a cold morning at just over 6000 metres in the Khumbu . With the right clothing and equipment, conditions such as this can be made quite comfortable, but an awareness of the acute risks posed by the cold remains crucial in any mountain or wilderness environment.
1. Cold Injury: The Risks
With good clothing, cold injury should not be a major concern in normal conditions, but there are a number of factors which can significantly increase the risk of cold injury. Being aware of these factors is crucial for all winter climbers and skiers, and for summer mountain adventures in areas where conditions can change rapidly. The factors divide into two broad groups: environmental and individual.
- Air temperature: the colder it is, the greater the rate of heat loss. This is the first factor to consider. Wind: wind increases the rate at which your body loses heat through convection. The stronger the wind, the greater the cooling effect or “wind chill”. Roughly speaking, every 5 km per hour of wind reduces the temperature by 1 oC.
- Damp: a damp body loses heat through much faster than a dry body, especially in windy conditions. Wet cold wet weather is much more dangerous than dry. Excessive sweating into non-wicking fabrics also presents a risk since the body will cool faster. As the diagram shows, the wind-chill effect can be considerable even on quite moderate days. To be warm you must be dry and sheltered from the wind!
- Cold water immersion: through falling into a river or breaking through the ice into a lake presents an extreme risk since the body loses heat very rapidly through convection.
A high camp at 5800 metres in the Khumbu, Nepal. Effective cold management at advanced base camps and high camps in mountain regions can make or break an expedition. The cold risks posed by inactivity whilst at camps should not be underestimated.
- Inactivity: exercise generates heat. Stopping after a period of exercise (on a summit, at a rest stop, or at a climbing belay) will make you much colder. The situation can be made worse if the earlier exercise has caused sweating leaving you damp.
- Hunger, thirst and fatigue: make it harder for the body to produce heat needed to keep you going in the first place. Hypothermia can set in later in the day when tiredness, dehydration and lack of food reduce the body’s defences, sometimes to dangerously low levels.
- Sex and physique: body fat (as well as being a store of energy) acts to insulate the body against heat loss. Skinny people will get cold faster than heavier people. Women tend to be more resistant to cold than men. Equally, children or small adults will be more susceptible to the risks of cold injury since small bodies have a proportionately greater surface area and so tend to lose heat faster.
- Poor or inadequate clothing: your clothing works just like the lagging on a hot water tank. It insulates the body and reduces the rate of heat loss. Good modern clothing is one the most crucial defences against the risks of cold injury.
- Illness or injury: can reduce the body’s ability to resist the effects of cold. Injury combined with inactivity is the reasons why hypothermia can be such a significant factor in other accidents (such as falls) where the victim survives the initial accident only to succumb later to the effects of cold.
2. Improvising Shelter – using a group shelter
When conditions are very bad, or if the group is gong to be inactive for a period of time (perhaps looking after an accident victim), you may need to take shelter. Taking shelter is all about reducing the risk of cold injury by removing the environmental factors (cold, wind, and damp). A group shelter is a brilliant device to carry since it can be set up in seconds and provides an amazing amount of protection.
Using a group shelter is straightforward:
- Everyone removes skis and packs.
- The group (two, four, six or more people depending on the size of the shelter) all stand in a tight circle facing inwards.
- Pull the group shelter over the heads of the group with the bottom dangling down towards the ground.
- At the same time, everyone kneels down sealing the bottom of the shelter against the base of the snow.
It can be a tight fit inside a group shelter but – especially in windy or stormy weather - it will feel amazing warm and beautifully quiet to be out of the wind. In bad conditions, the group shelter can provide an oasis of calm to take a break for some food, wait for slower members of the group, take time to plan a safe route out, or simply use the opportunity to make a go/no go decision in (relatively!) relaxed surroundings.
3. Getting shelter – building a snow cave
For longer term shelter - if you are unfortunate enough to get stuck out overnight, or if a big storm comes in and you need to take shelter for a few hours - your best option is to dig a snow-hole or snow-cave. Digging a snow cave is quite a major undertaking, but done right, these can be amazingly warm and comfortable and can protect you for days. There are many different designs, but again (sticking to the principle of this book) getting familiar with one simple technique is almost certainly the best approach unless you are planning to spend a lot of time learning how to dig snow caves!
The best technique for building a snow cave / hole is as follows:
- Choosing a site: choose a site free of any avalanche danger. Look for a drift or bank near ridges or trees where the snow depth is at least 1.5 metres. Arrange the entrance to the cave so that it faces away from the wind.
- Digging the entrance trench: Using your shovel, dig a trench about 2 meters long by 60cm wide at the entrance of the cave. Dig downwards until the trench is as deep as you are tall. As you dig place the snow that is being removed from the trench onto the roof area of the cave.
- Tunnelling in: At a point at about knee level make the entrance. Make the tunnel slightly wider than your body, and tunnel at a slight upward angle so that the cave end is at least a foot above the entrance. This gets you away from the colder sinking air. Dig until the tunnel is the same length as your body then, at the upward end, hollow out a space as large as your body.
- Shaping the cave: The cave walls need to be at least 30cm thick. The thicker the walls the more stable the structure and the better it will insulate. The ceiling and the walls should be dome shaped and smooth and should be large enough for you to sit upright. Try to eliminate any sharp edges or ridges on the walls and ceiling of the cave. Initial shaping can be done with a shovel to do the bulk of the work. Final shaping is best done with a gloved hand. This shaping prevents water dripping as the temperature in the cave rises.
- Finishing touches: A raised sleeping platform is a great addition to your shelter. This allows you to be nearer the warmer air in the upper part of the cave. Another essential feature is a 5cm ventilation hole to keep the air fresh. This hole should be made in the top using a ski pole or ice axe. Check the hole at regular intervals to prevent it from becoming clogged. Leaving a stick or ski pole in the hole is a good idea. To clear the vent hole just wiggle the inserted stick or pole. Others shelves and platforms can be created for gear and equipment. If you have a candle, this can provide light and raise the temperature. The entrance to the cave can be blocked with a snow block, pack or other gear. This will further help to reduce air movement and increase the temperature inside.
- Settle in and wait: Settle down and enjoy the night! Snow caves are never brilliantly comfortable, but if you are caught out at night or in a big storm they can be the difference between surviving and dying of cold injury. At night or in bad conditions, you best bet is to get some rest and continue in daylight or when conditions improve.
The one variation on this technique you might need is if the snow is not deep enough to dig your trench – perhaps on the surface of a glacier with very little fresh snow. In this case, simply use your shovel to pile up a huge heap of snow. Keep adding snow of any kind – lumps, blocks, powder – it does not really matter. Leave the pile to consolidate for an hour or so and then simply tunnel your way in. This can work effectively in snow depths as shallow as ten centimetres.
4. Hypothermia – recognition and treatment
The symptoms of hypothermia can be hard to spot in the early stages, and its onset can be insidious. Unfortunately, treatment becomes harder the longer the situation is allowed to develop so the critical point is to spot the signs early and give the right treatment, or better still provide clothing and shelter before the condition is allowed to develop. Prevention is much better than cure.
The high and very remote wilderness region of central Iceland in midsummer: arctic regions, like the high mountains, are particularly prone to extreme and potentially fatal changes in weather conditions. The key point is - even if the weather is stable as in the photo above - to never go out without adequate clothing and equipment to protect you if conditions should suddenly change.
It is essential to distinguish between mild hypothermia (defined as a body core temperature below 35 degrees C) and profound hypothermia (body core temperature below 32 degrees C) as the treatment is different.
Signs and symptoms of mild hypothermia are:
- The victim will feel cold, shiver and have slowed reactions.
- They may become apathetic and clumsy and even undergo a character change. Their speech may become slurred.
Signs and symptoms of profound hypothermia are:
- At about 32 degrees Celcius shivering will stop, and pulse and breathing will slow.
- Further cooling will result in unconsciousness.
If shivering has stopped, you should assume profound hypothermia. The general treatment for mild hypothermia is to prevent further heat loss as the body should then have enough reserves to reheat itself.
- Get shelter out of the wind: using any of the techniques described above or any shelter available, the first priority is to get the victim into shelter and out of the wind to reduce the cooling effect.
- Insulate the victim from the ground: remember that conductive heat loss can increase rapidly if a victim is lying down.
- Change wet clothing for dry: any wet clothing must be removed to prevent further heat loss. Members of the party in good condition may need to give up clothing to the victim, although always being careful not to put more people at risk.
- Get the victim into a bivy sac: putting the victim into a bivy sac allows them to gradually re-warm using their own body heat.
- Offer food and drink (only if conscious!): food and drink can help considerably with re-warming, provided the victim is still capable of swallowing without choking.
- External heat can be applied: from hot drinking bottles if you have a stove to heat up water.
- Do not give alcohol!
With profound hypothermia, there is an increased risk of cardiac arrest so the victim must be handled gently and not allowed to exert themselves. The general treatment in the field is to slowly re-warm the victim as the body will not have sufficient reserves to reheat itself.
- Get shelter out of the wind, insulate the victim from the ground, change wet clothing for dry: exactly as before.
- Check the victim’s ABC: as described in the first aid section [LINK], feeling for the pulse every three minutes and remembering that these can be slow.
- Slowly re-warm the victim:
- Apply hot drinking water bottles, wrapped in a sock to prevent burning, to the neck, groin and armpits.
- Warm the environment, for example by carefully using a stove in your group shelter.
- Do not apply heat to the limbs as this can increase peripheral circulation causing cooled blood in the limbs to flow back into the body core.
- If no pulse or breathing are present, CPR may not be effective and there is a chance of causing cardiac arrest. If CPR is not given, the heart may recover of its own accord as the body is re-warmed.
- No ill effects will be suffered from hypothermia provided it is caught and treated effectively, but vigilance at all times is important to prevent a minor situation deteriorating into a potentially tragic one. Hypothermic victims should in addition always rest for at least 48 hours to allow the body and heart to recover.
Enjoying perfect champagne powder on a freezing February morning high above Courmayer, Italy. To stay safe in the mountains in winter, and to make the most of conditions like this, an awareness of the risks posed the cold, and how to deal with them, is essential.
5. Frostnip and Frostbite – recognition and treatment
Frostnip is the superficial freezing of tissue (often the cheeks). The area will be painless, numb and have a waxy appearance and feel. The treatment is to cover the area with a hand to re-warm it and then cover with clothing to prevent a recurrance. Frostbite is the freezing of deep tissues. Frostbite should rarely be a major concern in most off-piste conditions, provided the symptoms are spotted and prompt action is taken. The danger signs are:
- The body part may feel painful,
- Loss of feeling in hands and feet,
- The area looks pale and white or (in severe cases) purple.
In cases of frostbite, the victim must be removed for hospital treatment as soon as possible, after treatment for hypothermia or any other injuries. The basic steps in the field are:
- Get out fast: if the frostbite is at all serious, the victim must be evacuated immediately since treatment depends on drugs and other processes which you will not have available.
- Do not thaw frozen tissue: if the tissue is badly frozen, it is best to get out before attempting any treatment since, for example, walking out on thawed or thawing foot will do more damage than walking out on a frozen foot and getting treatment at a hospital.
With proper clothing and a degree of care, frostbite should not be a major risk in any off-piste skiing environment. The risks are greater in high altitude mountaineering where the precautions should be stricter, and in particular the need to be able to take shelter from bad conditions is paramount.
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