Cold Wild Weather

As the earth turns and the seasons change, winter grips the planet.

Of all the elements, cold is our deadliest enemy.

From ice storms to avalanches, frostbite to heart attacks, cold is a killer.

I'm Donal MacIntyre. I'm about to follow winter's advance from its home in the Arctic,

as it brings some of the most dangerous weather on the planet.

I'm about to be buried alive, frozen solid and plunged into the lethal, white heart of winter.

This is Wild Weather.

My journey with cold starts here, on the very top of the world.

The Arctic has claimed hundreds of lives, as explorers battled the extreme elements to get here.

But I've chosen a quicker way.

Unconventional, I agree,

but it gives you a bird's-eye view of the top of the WO-O-O-ORLD!

Amazingly, this beautiful and awesome landscape

is the source of all our cold weather in the northern hemisphere. I've come here to find out how winter begins.

The Arctic is the area north of 66 degrees latitude.

Frozen all year round, it's an area of harsh scenery and frozen beauty.

This is the world's largest ice cube.

The scale of this place is breathtaking - 16 million square kilometres of solid ice.

That's bigger than India and China put together.

What is strange is that there is very little weather to speak of.

I expected blizzards and blinding snowstorms.

It's sunny, there's a light breeze and very little snowfall.

It's just like a desert, and in fact it is classed as one,

but a desert that's permanently frozen.

To find out how this place generates our winter weather, we have to know what keeps it in this state.

We think of earth as a blue planet.

But look at it from above and it's white - frozen solid all year round.

That's because the planet is tilted on its axis.

During our winter, the Arctic is turned away from the sun.

It's always night and temperatures plummet as low as minus 50. Winter shrouds the northern hemisphere.

As the year passes, the earth continues its orbit and the North Pole tilts towards the sun.

The seasons change and summer returns to the north.

Up here, the sun shines pretty much 24 hours a day,

which is why it's called the Land of the Midnight Sun. But even this is not enough to break cold's grip.

In the Arctic, as you can see from my shadow, the angle of the sun is so shallow

that its rays simply bounce off the surface, reflecting its energy rather than absorbing it.

This keeps the temperature of the surrounding atmosphere constant

and helps perpetuate the polar climate.

Even at the height of the Arctic summer, temperatures only creep above freezing.

But it's not enough to melt the ice.

Which is just as well, because I'm not standing on solid rock.

A few metres beneath my feet is the Arctic Ocean.

And just to prove it, I'm going to take a look,

because this vast layer of ice holds the key to cold's grip on the poles.

It's spectacular - a layer of ice up to ten metres thick.

And it's all frozen fresh water.

There's about as much salt in it as your own home freezer,

because when sea water freezes, it locks out the salt.

And it's this vast, freshwater ice sheet above me that's the key to winter's energy.

It works like this -

the ice keeps the air immediately above it at almost the same temperature.

Above this layer, warmer air is also sinking down, which forces the colder surface air to slip south.

This shimmering air looks just like a heat haze

but is in fact the first wisps of the polar wind.

This is what carries winter out of its Arctic lair.

This icy blast accelerates the further south it travels.

I'm going to follow the polar wind as it brings the wildest, most destructive weather into OUR world.

This far north, east and west have little or no bearing.

From here, all directions point south,

which leaves me, as it does winter, only one way to go.

Even 1,000 miles south of the North Pole, cold still grips the planet.

And yet even here, faced with the worst extremes of cold weather, people make their homes.

I've come to one of the most northerly inhabited settlements on the planet,

Ittoqqortoormiit in Greenland. It's home to one of the most hardy peoples on earth - the Inuit.

So if they can survive out here, maybe they're different from me.

-Hi. Great to be here.

-Yes. Nice to meet you.

The weather here is among the most extreme on the planet.

In winter, temperatures can drop to minus 40.

Children can only play outside for ten minutes before their skin freezes solid.

But a lifetime's exposure can prepare you for the worst.

How do you survive out here? I've got three pairs of gloves under here AND mitts.

-My fingers are still cold. How can you keep so warm?

-When I was young

and begin to hunt, I freeze very much.

But I learn to use my hands even when they're very cold.

It's...it's training.

So the Inuit are no different from me.

We are simply not designed for cold because we evolved in the tropics.

Even after thousands of years of Arctic weather,

the Inuit have remarkably few physical adaptations to the cold.

It's our inventiveness, not evolution, that keeps us alive - clothing, shelter, heating.

Only a madman would challenge the Arctic cold without any kind of protection.

So, in order to see what it does to me, I've come here to a controlled environment

to find out just what happens when the body is exposed to extreme cold.

Not the best place to be in your underwear!

According to cold expert Dr Frank Golden, most people can only stand this kind of cold for half an hour.

I'll be constantly monitored and, unlike the real Arctic, I can walk out of here any time.

-Good luck to you.

-Thank you very much.

The temperature here is minus 18. It's bloody freezing! Not the best place to be without any clothes on.

But at least it's getting my temperature down quickly for my body to react.

Our bodies keep our vital organs at a stable 37 degrees Celsius. It's called the core temperature.

I'm going to have to work overtime to try and maintain it.

He's not long in the cold, but he's beginning to shiver.

He's shivering to try and produce more heat.

Notice the way he keeps his arms and his elbows close to his side and his arms across his chest.

He's trying to shut down the surface area through which heat is being lost.

The only way to try and keep warm is just to try and move.

He's not sure what to do with his body.

But he knows he can't generate enough heat by shivering alone,

so he's not sure whether he should exercise harder to produce more heat.

His temperature's just falling. There's nothing he can do about it.

After a very short time, my body simply can't generate enough heat

and my temperature is on the way down.

My core temperature has fallen two degrees, which means I am now hypothermic -

my muscles are stiffening and my brain is cooling. If I lose my wits, I'll have no chance.

Even shivering stops, as the muscles slow down. And now, a little test.

Can you count down from 100, taking a seven away each time?

100 minus 7...

100 minus 7, OK... Uh...

100...100 minus 7...93.

Minus 7.

Uh...

8...100...

HE LAUGHS

86.

CHATTERING I feel like I've got the flu.

As all the vital organs start to cool, the whole body starts to shut down. This is the critical stage.

Then he would...he'd become tired and he'd just like to go to sleep.

But to survive, he'd have to fight through that phase and keep determined to keep alive.

But eventually, no matter how determined he is, the conditions will overcome him.

His temperature will fall to a level where he'll lose consciousness and eventually he'd die.

If my body temperature drops by six degrees I'll lose consciousness

and death is inevitable.

-He's in pain now.

-Oh, God!

I don't want to be here.

The time has come to pull him out now. He's had enough.

Come on, Donal, you've had enough. How are you feeling? God, you're bitterly cold, aren't you?

-I...

-Are your muscles stiff?

-My toes feel as though they're going to fall off.

-Your muscles are stiff?

-You can hardly talk.

-Oh, God.

-Oh!

-Come on, let's get you warmed up. Let me check you out.

In the real world, we need our brains to survive.

So if I can't last 40 minutes in minus 18, how am I going to survive out here at minus 30?

Erik Bruin and Mads Vadel must know. They have the most extreme tour of duty in the world.

For three months at a time,

the Danish Sirius Patrol travel the icy wastelands of north-eastern Greenland,

with only their training and a dog sled for protection.

For the next 24 hours, I'm going to join them to find out how they survive in nature's freezer.

-Hi.

-Hi, I'm Donal.

-Erik.

-Erik, hi.

-My partner, Mads.

-Mads, hi.

-Welcome to Greenland.

-These are your dogs?

-Yes.

-Beautiful! They don't bite?

-No.

'It's time to go.'

SHOUTS COMMAND Hup! ..It didn't work that time!

LAUGHTER

So...that's how you start?

It's a good idea to learn to ski before you become a member of the Sirius Patrol!

Let's go!

It was the weather that first brought them here.

In the Second World War,

the Danish had to defend Greenland from the Germans,

because if you know the weather here, you can predict the weather in Europe.

Today, the biggest threat to their patch is from the seals and, of course, amateurs like me.

But still, highly trained professionals like Erik, Mads and me are vigilant.

Out here, blizzards and snowstorms can strike without warning, and the cold is a constant threat.

Temperatures regularly fall below minus 40.

The thing about being out in the cold is that absolutely everything freezes,

including, in this case, my left eyelid.

The guys have told me that if your eyelid freezes closed,

use your hand to warm it up, then it melts and you can open it. It's dangerous to pull it open.

Yeah, I can feel it melting.

That's a good thing...

Now I can truly say I feel as cold as I probably look.

Oh! It just...

It just shows you, you've got to be careful. The cold's a killer.

As night falls, the temperature plummets. There's only one tent, so what happens to me?

I'm about to be buried alive.

Digging a hole deep into the snow can offer life-saving shelter - or so I'm told!

-What do we have to do?

-Well, we start making an entrance.

-Then we dig in and make it as long as you are, in this direction.

-A kind of ledge, OK.

-You will lay about here. So I will dig in and start.

-OK.

-So, that's my home.

-That's your home.

Try going in.

I can look forward to the night alone as the temperature drops below minus 30.

I have to say, I'm a bit apprehensive about being buried alive out here.

All I'll have to help me survive is a sleeping bag and some candles.

It's about a metre and a half high

by two and a half metres long...

and...

about...

..a metre and a half wide.

My entrance is there. There's always a gap for oxygen to come through.

An emergency link with the Sirius Patrol if anything goes wrong,

if this starts to cave in, but it shouldn't do cos it's well built.

Hi, guys. It's Donal here, just to say - no worries and see you in the morning. Over.

OK.

I'll see if they respond. If not, well...

I just hope they'd be listening if something DID go wrong!

OK...

It's...the middle of the night here. It's about minus 30 outside.

There's one big problem here in the Arctic -

any bit of exposed skin is liable to get frostbite after a few minutes.

Which brings me to the problem of going to the toilet! I don't think so.

Amazingly, the temperature inside the hole stayed 25 degrees warmer than outside.

The snow works as a surprisingly good insulator.

So, I spent the night in what, for the Arctic, was a cosy minus five degrees!

-Morning, Donal.

-Morning.

-Morning, guys.

-How are you?

-Good. Good.

-Do you want to go have a cup of coffee?

-That's a great idea.

The Sirius Patrol are trained to cope with the severe Arctic weather,

but when it hits the places we least expect it, the consequences can be horrific.

This isn't Greenland.

This is New York State in early spring 1993.

Four feet from us, our tracks were gone. We couldn't even find where we just came from.

The wind blew us down and our eyelids froze. You had to hold your hands up here so it wouldn't sting.

The 12th March 1993 saw the entire east coast of the US gripped

by one of the wildest winter storms in history.

The latest satellite shows a huge storm system coming up the coast. Very heavy snows for our region.

12 to 24 inches for the Capital Region by midday tomorrow.

In upstate New York, Geoff Smock and Bill Simons were relaxing after work.

Several hundred miles away, the storm was growing and heading their way.

Outside it started to snow. But that wasn't unusual for the time of year.

As they set off home,

they had no idea that they were about to be overtaken by a blizzard that would change their lives for ever.

Full-blown blizzard conditions are over the Capital District and western New England.

High winds and dangerous cold...

The snowfall was extraordinary. Bill and Geoff ground to a halt half a mile from home.

They decided to walk the last leg. That's when their nightmare began.

You couldn't go forwards or backwards. There was no place to go.

It was like ploughing through five foot of snow. You get to a certain point and you're exhausted.

You'd look up and you're in a hole.

Our original thought was we'd stay at the tree to wait for the wind to calm down

and then start heading home. But...lo and behold, the weather just kept getting worse and worse.

By now, the winds were gusting at 145mph,

temperatures had plummeted way below zero and the snow was drifting as high as ten metres.

All over the state, the blizzard was tightening its grip.

'The death toll from the blizzard of '93 is mounting. Seven people reported dead...'

Back at the tree, the storm was getting worse. Geoff and Bill had been stuck here for eight hours.

I couldn't walk. Maybe about ten feet from the tree, my feet just gave out.

I tried to stand up and couldn't. I had to crawl back here.

-That's when I said, "Bill, no-one's looking for us."

-Nobody knows we're here.

-Right.

They were trapped. As the night wore on, the temperature fell even lower,

hitting Arctic extremes of minus 40 degrees, and still the storm raged around them.

By the time morning came, Bill and Geoff had spent 18 hours exposed to Arctic conditions.

Amazingly they were still alive.

Geoff managed to struggle through the snow and raise the alarm.

It was another six hours before the rescue services could get to Bill.

But the cold had left a devastating legacy. They had both suffered winter's vicious touch.

I tucked my hat in my shirt...

and it pulled up the back of my clothes and exposed my back and the top part of my buttocks.

I got severe frostbite. There's no feeling

and the nerves are gone. They did skin grafts.

Two surgeries.

My feet, my hands, my butt...

My knees had gotten it. The calves of my legs had it because of the way I was sitting on the ground.

My hands were blistered, as huge as softballs.

Deep frostbite is a one-way process.

The cold literally freezes the skin tissue. Ice forms in the fluid in and around the cells.

The tiny blood vessels freeze solid and no oxygen is delivered.

But worse is to come. With no blood supply, the cells can't fight infection.

Gangrene sets in and the affected area becomes black and starts to decompose.

Then there is no option left but to amputate.

After his ordeal in the freezing cold, both Geoff's feet were severely frostbitten.

I ended up getting skin grafts done on my hands, on my butt, my legs...

but I lost both of my feet from about four inches above the ankles. Both of them.

A wild weather event like this is rare, unexpected,

which is why the cost is so high.

The key to survival is to be prepared.

But even the professionals can get caught out.

In the last 50 years, the Sirius Patrol have lost six men under the ice.

Severe frostbite is always a problem,

but they know the risks and their love of this awesome landscape far outweighs the dangers.

Today, as the Sirius Patrol travels north into this wonderful wilderness,

I'm on a different journey,

travelling south with the cold, as it brings winter to the peoples of the northern hemisphere.

I'm going to a place that gets the first blast of winter's icy grip.

All that polar wind screaming south is about to crash into the warmer air from the equator.

When they meet, all hell breaks loose.

And the place right on the front line

is the Mount Washington weather station in north-east America.

It's here that the battle between hot and cold begins. But for now at least, all is quiet.

Mount Washington is the highest point in the north-eastern United States.

Although not all that high on a world scale, it's commonly known as the home of the world's worst weather.

'This morning, the temperature outside is down to minus nine degrees

'with wind from the north-west at 48mph.'

Forecast for the summit today is snow showers and winds of 40 to 60mph.

But don't hold your breath, because yet another system is approaching from the Great Lakes this afternoon.

So how does a sun-kissed mountain like this get such a bad reputation?

Well, the summit lies in the path of the principal storm tracks and air mass routes

that affect the weather in the north-east,

which makes it the perfect place to discover what happens when wind and cold combine.

Good morning. Welcome to the summit of Mount Washington, the home of the world's worst weather.

-Great to be here. The mountain's been very good to us today.

-You should've been here yesterday.

Just my luck - I came here to find the worst winds in the world and the weather was perfect!

But I didn't have to wait long. A few hours later, I saw why this place gets its reputation.

Within minutes, the blue skies turned to grey and the winds kicked up.

The highest wind ever recorded was here at Mount Washington -

a staggering 231mph.

The wind now is gusting at 60mph, and already I'm getting tossed about.

It's very difficult to stay up.

The first thing you notice when the wind gets going is that it feels much colder.

This effect is called the wind-chill factor.

So, in winds of 50mph, minus five feels like minus 38.

Wind and cold together multiply the deadly effects of winter,

which is why the Mount Washington observatory is the best place to study the extremes of winter weather.

That is, if the instruments don't ice up!

When the wind and a cold fog like this meet an object, something truly amazing happens.

The fog that surrounds me is made up of billions of water droplets.

The strange thing is

that they are all way below the freezing point but remain in liquid form called "supercooled",

but when they hit an object, they freeze solid.

These beautiful feathers of ice are called rime ice. It's as tough as nails.

This remarkable ability of water to remain a liquid way below zero

is the cause of one of the most extraordinary weather events on the planet - an ice storm.

And one of the worst ice storms in history hit eastern Canada with a vengeance.

This was the most destructive storm in Canadian history.

We have over a century and a half of weather-keeping in Canada and there was nothing to match this.

Ice storms are not unusual in Canada, coating the landscape with a beautiful shroud of ice.

But in January 1998, Canada was hit by a storm that was anything but usual.

At first, the ice storm of '98 was just as magical.

It was really more of an exhilaration. People were not too...

disrupted by that. School was cancelled, businesses closed,

but it was a winter wonderland.

It gives you that enchanted wonderland where the landscape looks so beautiful.

On the evening of the 4th of January, winter was still on the attack.

A bank of freezing polar air sat like a blanket over the north-east of the country.

At the same time, a mass of warm, moist air from Texas moved in above the polar air,

forming a wedge and trapping it beneath - perfect conditions for an ice storm.

But in the middle of the wedge,

rain from the warm air above doesn't have enough time to freeze solid on its way down,

so it falls as supercooled rain.

What happens is that the raindrop will fall through that wedge of cold air.

The liquid raindrop begins to cool but it doesn't get quite frozen.

It freezes to the point that it's "supercooled" - it's below freezing point, but it's still liquid.

Because the object that it hits is below freezing, it's almost shocked.

It makes that perfect transformation from the liquid to the solid.

It spreads out and freezes into a little veneer of ice

which is the toughest and most adhesive ice nature can produce.

Ice storms can be lethal, but usually the misery only lasts a few hours.

But the ice storm of January 1998 was different. It arrived in waves.

For two days, the freezing rain just kept coming.

This ice just kept building up.

And the wires kept getting bigger and all the trees around were building up with ice.

Look at the thickness of this ice compared to my hand.

You could have maybe four inches of ice around a small twig,

and, of course, that twig, that's part of a branch which is also encased in ice,

will, all of a sudden, have a different weight and it will break.

This condition kept up for hour after hour.

Gradually we started to hear the trees coming down and then the lines started coming down.

The trees were falling on the lines and the lines were falling down on their own because of the ice.

By the evening of the third day, the rain stopped, but the icy conditions continued.

Then satellites monitoring the storm saw another wave hit.

Thousands of square miles came to a virtual standstill.

Life was almost impossible.

'The freezing rain won't let up.

'If you do not have to go out, do not, unless it is absolutely necessary.'

On the Friday, what we call

the Black...the Dark Friday or the Cold Friday,

we suddenly realised that this was more than a usual ice storm.

Then we lost power for more than half of the province.

The lines of cables and huge transmission towers were crumpled to the ground like paperclips.

When you saw an electrical pylon suddenly buckle in front of your eyes,

you knew these were major problems.

If you can imagine, you're looking down this whole pile of poles

and you see them coming down one after another,

then you see the fireballs as the electricity is being cut off.

It looked like a war zone, really, it was so devastated.

The ice struck at the very heart of modern life.

Every house, factory and office in an area of half a million square miles was blacked out.

Without power and communications Montreal hit crisis point.

A centre was set up to co-ordinate emergency efforts.

An ice storm that's been called the worst weather crisis eastern Canada has dealt with.

Without electricity, millions had no heating, fresh water or sanitation.

It was fast getting out of control.

Emergency services couldn't cope and the government was at a loss about what to do next.

We saw desperation in people's eyes.

Temperatures plummeted to minus 15, minus 18.

Even after the ice storm passed, it took three weeks to restore power and get the city back to normal.

For four million people,

this ice storm was the weather event of their lifetime.

They never, in fact, will probably ever endure such an event.

In the end, 50,000 people were forced to leave their homes and take refuge in temporary shelters.

35 people died, and many more were left in a critical condition.

During the storm, 3,000 kilometres of power lines were destroyed

at a cost of over 800 million.

200 years ago, there wouldn't have been a storm.

200 years ago, the ice would have come and the ice would have gone.

People would have had wood in their fires, made muffins on their stoves, and it wouldn't have bothered them.

It now all depends on electricity, so it was devastating.

In our endless battle against the cold, the weather won and our technology was useless.

As my journey with winter continues south,

cold weather becomes far less extreme

but can be even more dangerous.

To prove it, I'm off to the cold-death capital of Europe.

Moscow? Helsinki?

No.

BIG BEN CHIMES London.

CHIMES AGAIN

Just because you can't see the ice and snow doesn't mean that cold isn't a killer.

In Britain, we very rarely experience the extremes that winter can bring, like ice storms and blizzards,

so it may be surprising to learn that there are more cold-related deaths in London than anywhere else in Europe.

In the mild climate we enjoy in Britain,

we don't feel we need to dress up warmly against the cold,

but even these temperatures can be deadly.

Even in water well above freezing, say, ten degrees Celsius, that's 50 Fahrenheit,

some one in six will be dead after just 15 minutes.

Now, it's a cold morning and the water in this lake is nearer five degrees.

Now... HE PANTS

Sorry.

Forgot that line!

The water in this lake is nearer five degrees.

Even a quick dip...

Even a quick...a quick dip...

as this heart rate monitor should show, should be enough to send my body's defences into overdrive.

HEARTBEAT POUNDS

'My body's progress is being monitored by Dr Rosemary Leonard.'

Quick! Here, put the towel around you. You're shivering like crazy.

-How do you feel?

-(I'm freezing!)

Let's just see what's happened to your pulse and your blood pressure.

'The monitor showed my pulse was 50% faster than my normal heart rate.

'Now for my blood pressure.'

160 - that's high.

160 over 100.

What's that reading telling you?

The blood vessels in the outer part of your skin,

and also inside your body, are narrowing down

to try and conserve the heat and the blood flow where it's really needed, round your heart and lungs.

'This is the normal response.

'As the blood vessels in my skin constrict, the blood in the rest of my body becomes thicker and stickier.

'And it's this everyday reaction to cold that can sometimes cause a sudden and painful death.

'It's a story that repeats itself every day across the city.

'A cold winter's morning. A commuter hurries to the station.

'The rush hour has begun. It could be you.'

-Pretty cold this morning.

-Yeah.

'No hat, no scarf, no gloves. So what? It's cold, but it's not snowing.

'As you wait for the train, your body is already shutting down the blood vessels nearest to the exposed skin.

'As you shiver, your blood is starting to thicken and retreat back to your vital organs.

'As it gets thicker and stickier, the nightmare scenario begins.

'A tiny clot starts to form.

'As you worry about being late, the clot is on time to reach your heart.

'That night, you suffer a lethal heart attack and never make that journey again.

'The coroner's report adds you to the statistics -

'death by natural causes.

'The figures show that in London over 3,000 extra deaths happen like this every winter.

'Across the UK, the figure is closer to 20,000,

'all victims of an invisible serial killer - cold.

'The real tragedy is that it could so easily have been avoided.

'My mother was right.

'All you need is a hat and gloves.'

Further south than London, winter's grip is even less extreme,

unless, of course, you go up high, where cold is always with us.

On top of the mountains or high in the clouds, there is always snow, even at the equator.

Wherever you are in the world, there's a good chance that there'll be snow above you.

Most of the time it falls as rain,

but up here, at high altitude, it falls as snow.

It's one of nature's miracles and winter's most distinctive hallmarks.

Snowflakes start life as tiny particles in the clouds.

Water droplets attracted to their surfaces freeze, forming ice crystals.

More water droplets are drawn to the crystal, which grows into a snowflake,

eventually heavy enough to fall to the ground.

The classic six-sided snowflake is the most common, but it's only one of several different types.

This is a plate...

..and here, two plates are joined by a column.

They can combine to form even more complex shapes as they fall.

Needles, columns and plates form the basic building blocks.

Under the electron microscope,

extreme close-ups of snowflakes reveal their almost unbelievable complexity -

the weather's miracle of engineering.

Each different type of snowflake forms a different type of snow...

..all with extraordinary properties.

Some can be as strong as concrete,

which is just as well if you're caught in a storm with Peter Marchand.

Peter is a snow lover,

a winter scientist who spends weeks researching out in the snowy hills of Colorado.

He needs nothing out here except a few feet of loose snow.

Ever since my father got me out on skis as a small child,

I became interested in snow as a material.

When snowflakes fall to the ground they don't remain soft and powdery

but under their own weight bond together into a solid mass.

It's this bonding process that allows nature to make these wonderful snow sculptures -

but it's also what allows Peter Marchand to build himself a shelter.

What I'm doing now is building a snow house. It's called a quin-zhee.

The process is almost magical.

Just piling up loose, powdery snow puts pressure on the surface of the snowflake.

It melts, forming a thin layer of water which sticks the neighbouring crystals together.

Over time the water freezes, bonding the snowflakes together.

There! We'll give it a couple of hours to complete the process of bonding

and we'll come back, dig it out and have ourselves a shelter for the night.

A few hours later, the pile of loose snow has turned into a solid block

that Peter simply hollows out

to form a sturdy shelter against the wildest winter weather.

It's a very strong structure.

It seems to get stronger with time

and can be used over and over again You can move on and come back to them.

It's just really a beautiful material, free of charge.

For as easy as they are to build, they're as easy to walk away from.

You have nothing to fold up, to put on your back or on your pack animals and carry with you.

Mark Twain said of the cold in North America,

"If the thermometer had been an inch longer we'd all have been frozen to death."

We complain, but winter also has its pleasures.

The same bonding effect that built Peter's snow shelter

makes the perfect surface for winter sports.

But when that bonding fails, the results can be terrifying.

THUNDEROUS CRUNCH

Looked left, saw a big crack. Looked right, saw a big crack. "Oh - I'm in an avalanche."

Whilst filming a TV programme,

expert skier Nick Farquit was caught in one of cold's most powerful and frightening killers.

Came up for one breath and got engulfed again...

then hitting the snow at the bottom,

and the rest of the avalanche pounding me down like a hammer - boof, boof, boof!

He was lucky to survive. Each year, many hundreds don't.

Snowfalls usually build up into strongly bonded layers.

But sometimes one layer remains weak.

Even the vibrations from a skier can cause the layer above to slide off.

In seconds, hundreds of thousands of tonnes of snow hurtle down the mountainside at over 100mph.

With so many people visiting ski resorts each year, avalanches are a real threat.

Dedicated teams of Avalaunchers are locked in battle against the weather.

Their job is to seek out potentially dangerous build-ups and overhangs of snow and dynamite them.

Sometimes the unpredictability of the weather can catch us all by surprise.

The little town of Galtur should have been safe from the threat of avalanches.

But a freak combination of weather systems made it the victim of one of the deadliest in the Alps for years.

It had been snowing heavily for several days.

Deep snow was piling up on the mountain above Galtur.

In addition, high winds changed direction and began to lift more snow on top of it.

But what no-one knew was that underneath this huge mass of new snow was an unstable layer.

A few days of warm weather had previously melted the surface, which had turned to ice.

The new snowfall couldn't bond properly to this hard, icy layer.

No-one knows just what triggered it

but, in seconds, over a third of a million tonnes of snow tore down the mountain

at a devastating 186mph.

This monster wiped out everything in its path, and the town of Galtur was crushed under its weight.

38 people died.

It was the worst disaster for 30 years.

Up here in the mountains, the weather has one more trick up its sleeve.

The snow that brings the devastation of avalanches also creates cold's most enduring monument - a glacier.

Well done. You can see where we've got to go, along the white ice here,

then up into the green ice here on the glacier. A long way to go, still.

Mountain guide Russell Bryce is taking me to the source of the Argentiere,

one of the Alps' most impressive glaciers.

To understand how it forms and what it does to the weather,

we have to climb it.

Down here at the base, it SEEMED like a good idea.

The glacier has been here for over 10,000 years.

It takes the ice 500 years to travel from the top to down here.

Way above us lies the source of this great stream of ice.

Surprisingly, it starts life as snow.

Over time, the crystals bond together to form the ice.

As it falls, year after year, layers of snow become crushed

into little ice crystals that fuse together.

The weight of new snow compresses the ice below even more,

eventually turning it to pure, blue, glacial ice.

When the glacier is big enough it starts to move,

and over thousands of years a vast river of ice is formed.

As it flows, it breaks into enormous crevasses.

The glacier is over six miles long and two miles wide.

-It's amazing in here.

-Yep.

It'll be quite hard to get out, though. Look how hard this ice is.

It'll shatter... You see how it's cracked all round here?

-How do you get a grip on that?

-Well, that's what we'll have to do!

What is it that makes this extraordinary thing?

-So smooth, and with all these layers.

-Sheer weight.

The weight of the ice on itself. If you take a handful of snow...

and you squeeze it and squeeze it...

-If you squeeze that really hard, you'll make it ice.

-The amount of pressure that's created that!

How are we going to climb that, now?!

Quite hard ice here at the moment...

Quite delicate, really, isn't it?

Climbing!

-I need a little slack.

-Got it.

-Yeah, that's good.

-It just seems impossible to get a grip.

-That's it!

-Keep me tight.

-Can you get your ice-axe in?

OW!

-You OK?

-TIRED LAUGH

-How are you doing?

-OK...!

Just to the left, there.

-Oh, what a relief.

-Yeah.

-Excellent.

-Not very graceful!

-It's good.

For every 100 metres we climb, the temperature drops half a degree.

It's the mix between the cold air up here and the warm air blown up into the mountains from below

that can make the weather so ferocious.

But it's also what creates the snow which makes the glacier.

'Finally, the peak of the mountain! This is where it all begins.'

Here we are - the old Holy Grail.

-You see the neve in here?

-Yeah.

-This is the collection area.

-This is what actually collects all the ice and snow.

-Where a glacier would actually start.

This is truly one of the most spectacular, beautiful sights I've seen in my work on this programme.

It also is one of the coldest and one of the most terrifying sights.

To see those crevasses down there... How big and how deep are they?

-Those, maybe 50 metres deep.

-If somebody fell in there, you haven't a chance.

You'd die. For sure.

Just...a staggering landscape.

But this wonderful landscape is changing.

Across the whole Alps, almost half the ice has melted, and 100 glaciers have disappeared altogether.

And all this in the last 150 years.

Why?

Global warming. And if it continues,

by 2050, ice cover will be just 20% of what it was a century and a half ago.

All across the world, the story is the same.

From the Andes to the Himalayas, glaciers are on the retreat,

melting faster than the snows can replenish them.

But the real problem is here at the poles.

If the ice - north and south, including the glaciers - all melted,

the sea level would rise by 20 feet, submerging low-lying cities like London, New York and Tokyo.

The irony is that cold, our greatest enemy, is also preserving the world as we know it.

Back up north, in winter's lair, my journey is at an end.

I've learned to respect nature's most powerful weapon.

I've seen the devastation cold brings in all its forms - ice, snow and freezing rain -

and how powerless we are against it.

Like all weather, winter and the cold it brings is uncontrollable and unpredictable.

We must learn to live with it and prepare for the worst it has to offer.

I for one will never take cold for granted again.

'In the next programme, I'll follow the violent journey heat takes

'from the steaming jungles of the equator,

'through the blinding heat of the deserts

'and on into an uncertain future.

'Our world is warming up and our weather is getting wilder.

'I'll try and find out what the future holds.'

Oh, my God!