Frozen Planet.S1.E7 ∙ On Thin Ice
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TVTranscript
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00:30This white wilderness, this emptiness is the North Pole. I'm standing in the middle of a frozen ocean
00:41beneath my feet and for over 500 miles in every direction there are several meters of ice
00:50but something significant is likely to happen here at the North Pole soon. Chances are that sometime
00:59within the next few decades, perhaps even as soon as 2020, there will be open water here
01:07for the first time in human recorded history.
01:13The Arctic and Antarctic are changing. Enormous masses of ice that have been
01:18frozen for thousands of years are breaking apart and melting away.
01:37Ice scientists are going to extremes to find out exactly what's going on. For them these are
01:44exciting times but the transformation that's being seen here will be felt far beyond the
01:50polar wilderness. In this program I'll be trying to understand what these changes mean
02:03not just to the wildlife and people that live around the poles but to the whole planet.
02:14I'm starting my journey in the Arctic, the far north of our planet.
02:29It's still very cold outside by most people's standards
02:33but the Arctic has been warming fast, twice as fast as the rest of our planet.
02:38My first mission is to find out what effect that's having on the animals,
02:43although first we have to find them. It's April in Svalbard. We're a thousand miles
02:51north the Arctic Circle in search of the region's top predator.
02:57We need to travel away from the land and out over the frozen sea.
03:18There's some tracks right beneath us.
03:27Over there.
03:31I'm with a Norwegian team which is giving the polar bears of Svalbard their yearly health check.
03:41She's under us now. I'll come around for a clean shot.
03:48The team works together to give an anaesthetic injection from a dart gun
03:54without hurting the bear. It takes tremendous skill.
04:04Ah, you've got it!
04:10I'll just back up until she's free.
04:18Nobody likes to see a magnificent animal like a polar bear lolling about unconscious on the ice,
04:32but it's only by darting them in this way and keeping check on them year after year
04:37that we can be sure we know what is happening to them and the population of polar bears as a whole.
04:44Over the last 30 years, many teams have been seeing the condition of their local bears deteriorate,
04:51although not every bear is suffering it.
05:03How much? 96 here and 102 here, so that's 197.
05:1097. Is that good? It's not too bad, it's a bit above average.
05:17So she's bearing a good condition for Svalbard to be. The trouble is that if this was underweight
05:25she would be in trouble, not only from her own point of view but from the point of view of her
05:30cubs, because an underweight female gives birth to underweight cubs and underweight cubs have a
05:37great problem of surviving their difficult first year in these circumstances.
05:44It can be minus 40 degrees centigrade when polar bear cubs emerge
05:49at the start of the arctic spring from their dens where they were born.
05:53This mother hasn't eaten for half a year.
06:11She and her cubs need to fatten up fast over the next few months
06:15and their chances of survival depend on what's happening beneath their feet.
06:23These polar bears aren't walking on land, they're roaming across the frozen surface of the sea.
06:34And the bear's food lives under the ice.
06:40Ring seals are hunted by polar bears. In fact in some parts polar bears eat almost nothing else.
07:01So it's fairly understandable that this mother ring seal was looking at me now.
07:10She'd be a little apprehensive.
07:15That pup of hers is only about three or four days old
07:22and the pup won't be able to swim for another two or three days.
07:28Seals have good reason to be nervous around their holes.
07:33They need the holes to breathe when the sea is frozen but this makes them easy to find.
07:41Polar bears can sniff out seal holes even if they're covered in snow.
07:52Spring is the best hunting season.
07:57This mother's found a food store under the snow that was probably made by an arctic fox.
08:05It's a time of plenty now but the bear family need to make the best of it
08:09because the good times are about to come to an end.
08:18As the weather warms the ice beneath the bear's feet starts to break up
08:23and then melt and as the ice dwindles so do the bear's chances of a successful hunt.
08:33Most of the ice is lost over the shallow coastal waters where most of the seals live.
08:40It's now summer and these bears have a choice.
08:48Take their chances on the shrinking ice flows or make for the safety of the land.
08:58It's a case of sink or swim.
09:01Bears have always gone hungry in the summer but the length of time when there's enough
09:05ice for them to go hunting is getting shorter and shorter across much of the arctic.
09:14This is hitting cubs particularly hard because they can't survive for as long
09:20without feeding as their mother.
09:21Cubs that were born underweight are at the greatest risk.
09:37This mother and her cubs may well not get another meal until the sea freezes again in winter.
09:43There's not much to eat on land and the fact is that the longer the cubs have to wait until
09:47the ice returns the more likely they are to die.
09:54Longer summers with no ice are probably the main reason why many polar bear populations are dropping.
10:01To help monitor bears into the future this female is being fitted with a radio collar to track her movements.
10:11It's an extraordinary sensation to be able to monitor a bear.
10:15To help monitor bears into the future this female is being fitted with a radio collar to track her movements.
10:29It's an extraordinary sensation to be so close to such a powerful animal.
10:35With luck carrying that collar she will have more years to go yet
10:42and be telling us a great deal about herself and the rest of the race of polar bears
10:49as they face this very uncertain future.
11:00The future of the ice cover on the sea isn't just an issue for the animals.
11:05It's a big concern for the people who live in the arctic and travel across the ice every day.
11:11David Ikakrolu is an Inuit from the village of Clyde River in the Canadian far north.
11:32There are very few roads up here so David and his community like most Inuit people
11:37have always traveled across the frozen sea.
11:42Dog sleds are the safest way to get around because the dogs feel thin ice underfoot
11:48and won't lead travelers into trouble.
11:53Old-timers like David know the ice as well as we know the streets in our local neighborhood.
12:02Every spring cracks have always formed in the same places at the same time.
12:07It's going to be big very soon, after two weeks maybe, will be more open.
12:17But now cracks are appearing where they never did before
12:21so David and his friend Laimiki have taken on a new job.
12:27They are using special GPS units to record the position of new cracks or weak ice.
12:37These findings will be used by locals for their own safety
12:40but they're also being studied by ice scientists
12:43who want to predict how the ice will change in years to come.
12:55The Inuit are keen to know what the future holds too because they've seen with their own eyes
13:01the changes that the scientists have seen from space.
13:04This satellite photo from 1980 shows the Arctic Ocean at the end of the summer
13:09when ice cover is at its minimum.
13:12Since then, there's been a 30% drop in the area covered by ice.
13:19But these images can't tell us about changes to the most important factor,
13:25the thickness of the ice.
13:27Measuring thickness across the whole ocean was beyond scientists for many years
13:32until help came from an unexpected source.
13:57The Arctic Ocean is of huge military importance
14:01as it's the shortest route between North America and Russia.
14:10Since the late 1950s, British, US and Russian submarines
14:15have been patrolling the Arctic Ocean.
14:20But as well as looking out for enemy activity,
14:23they've also been measuring the thickness of the ice.
14:27Critical when looking for a place to surface.
14:33When scientists got permission to look at the submarine crew's records,
14:37they discovered that the ice has been thinning fast.
14:40In fact, it's nearly halved in thickness since 1980.
14:48Across most of the Arctic Ocean, there are now just a couple of metres of ice.
14:57It's so thin that it could melt away almost entirely in the summertime
15:02and that includes the ice at the North Pole.
15:06If current trends continue,
15:08then there will be open ocean here by summer's end,
15:11sometime within the next few decades.
15:16So, the days of the Arctic Ocean
15:18being covered by a continuous sheet of ice seem to be past.
15:23Whether or not that's a good or bad thing, of course,
15:26depends on your point of view.
15:32Nobody has had a better view of the changes to the Arctic Ocean
15:35than the people of Barrow, the most northerly town in Alaska.
15:39The people here have always survived by hunting on the frozen sea
15:43and they celebrate this at a festival every year.
15:48The blanket toss was once the best way to spot distant animals to hunt,
15:52as lifelong resident Lewis Brower explains.
15:55When we throw ourselves up into the blanket, you know,
15:57you get that much more of an awe of seeing further and further out.
16:01So, sometimes you'll jump 15, 20 feet in the air
16:05and hopefully you're being caught right back into the blanket.
16:14But the old way of life is under threat.
16:16When Lewis was young, the sea stayed frozen to the horizon until July
16:21and some ice remained offshore all summer.
16:25But now it's breaking up in June and melting away completely for two or three months.
16:31I used to go out on the ice all the time this time of the year,
16:35but we can't do that anymore because there's no more ice.
16:42Lewis can also see that the loss of sea ice
16:45is affecting the animals he hunts for a living.
16:49Since 2007, something very strange has been happening
16:52on this stretch of coastline close to Barrow.
16:59Mother walruses, confused by the lack of ice,
17:02are crowding onto the land with their pups.
17:06This very tight crowding isn't normal
17:09and it's caused many youngsters to be crushed to death.
17:12Many Arctic animals are threatened by the changing conditions
17:15and that's also bad news for the traditional hunters.
17:19But the ice loss could be good news for some people.
17:28There are trillions of dollars worth of oil and gas under the Arctic Ocean.
17:33But the only way to get to them until now
17:35has been by building expensive artificial islands.
17:38But if the sea ice goes,
17:40it will be much easier to drill for the huge riches below.
17:44So the countries that surround the Arctic are scrambling to stake their claims.
18:00This daring attempt by the Russians to take over the Arctic Ocean
18:05This daring attempt by the Russians
18:08to claim the disputed seabed at the North Pole in 2007
18:13caused fury among the competing countries
18:15and it's unlikely to be the last such dispute.
18:21The Arctic has never been so important
18:23and not just because of its resources.
18:29The Northwest Passage,
18:30a legendary sea route around the north of Canada and Alaska,
18:34cleared of ice in the summer of 2007
18:37for the first time since records began.
18:40This promises a much faster and cheaper shipping route
18:44between the Atlantic and Pacific Oceans.
18:50And some wildlife could benefit from an ice-free Arctic too.
18:55Bowhead whales are one of just a few whales
18:58that can live year-round in the Arctic
19:00because they have no dorsal fin.
19:04This means they can come up for air in small spaces
19:07and travel easily under the ice.
19:11Their unique body shape used to mean
19:14that the Arctic whales had the seas to themselves for most of the year.
19:18But now, some customers say,
19:20Killa whales are now a much more common sight in the Arctic.
19:25Their tall fins make it difficult for them to travel under ice,
19:29but the longer summers mean they can travel much farther north
19:32and make the most of the rich Arctic seas.
19:38The Arctic is a great place to live.
19:40It's a great place to live in the Arctic,
19:42and it's a great place to live in the Arctic.
19:44It's a great place to live in the Arctic,
19:46and it's a great place to live in the Arctic.
19:49For animals and people,
19:51it will be those who can adapt who will thrive in a changing Arctic.
20:05But the loss of sea ice isn't just an issue for the Arctic
20:08because the state of the ice affects the climate of the whole planet.
20:14The Arctic is a great place to live in the Arctic.
20:16The Arctic is a great place to live in the Arctic
20:19because the state of the ice affects the climate of the whole planet.
20:25Because it's white, the ice reflects up to 90% of the sun's energy.
20:30This is called the albedo effect,
20:33and it's why we often see heat haze in the Arctic,
20:35even when the air feels cold.
20:38The frozen Arctic Ocean acts as a huge reflector,
20:42bouncing back the sun's heat into space.
20:45Throughout history, that has helped to cool the planet.
20:49But when the ice melts, it's a different story.
20:58Because seawater is dark, it absorbs most of the sun's heat.
21:04In the Arctic, this can trigger a chain reaction
21:07as the warming water melts more ice,
21:10exposing more water to the sun's heat.
21:18This cycle of warming, as huge areas start to absorb rather than reflect heat,
21:23is the main reason why the Arctic, a region the size of North America,
21:27is warming twice as fast as the rest of the Earth.
21:35So, melting sea ice is a big issue,
21:38but there's another kind of ice
21:39that could have an even more dramatic impact on our world.
21:44The ice that is found on land.
21:49This is freshwater ice,
21:51formed from thousands of years of accumulated snowfall.
21:56This is the front of a glacier, quite a small one, believe it or not.
22:02Glaciers are like rivers of frozen fresh water
22:05flowing across the surface of the land.
22:08This one, like most polar glaciers,
22:11is flowing down from a vast inland ice sheet.
22:16And it's very, very cold.
22:18It's a very, very cold glacier.
22:21It's flowing from a vast inland ice sheet.
22:25And it's what happens to those ice sheets
22:28that could radically alter the face of the planet.
22:33The Greenland ice sheet is by far the largest in the Arctic.
22:36It's two miles thick in places
22:39and six times the size of the United Kingdom.
22:43Every summer, some of the surface of the ice sheet melts,
22:47forming sapphire-blue lakes of meltwater.
22:52More and more of these lakes have been forming
22:55as Greenland has warmed over the last 20 years.
22:59This lake has grown over several weeks,
23:02and now it's overflowing,
23:03carving a deep channel through the ice.
23:07A network of channels criss-crosses the ice sheet,
23:10but many of them come to an abrupt end.
23:24Huge amounts of water flow through the ice sheet,
23:27and the ice sheet is so thick,
23:29it's almost impossible to see the bottom of the ice sheet.
23:34Huge holes like this can open up quite suddenly,
23:38draining the meltwater away.
23:51Alan Hubbard is a glaciologist,
23:54studying the enormous power of these waterfalls,
23:57which are known as moolands.
23:59We've got this amazing mooland going on here today.
24:03The water's overflowing from the lake,
24:05which is beginning to drain.
24:07Tons of water cascading down this pipe
24:11that is effectively plummeting to the depths of the ice sheet
24:15through over a kilometre of vertical ice.
24:20Alan is here to study where the meltwater goes
24:23and what effect it has on the remaining ice.
24:26To do that, he needs to find a mooland
24:29that has recently run dry.
24:37Just a week ago, there was a three-mile-long,
24:4010-kilometre-wide mooland.
24:43The ice was so thick,
24:45just a week ago,
24:47there was a three-mile-long, 10-metre-deep lake here.
24:51The weight of all that water cracked the ice beneath
24:55and the lake drained in just a few hours with incredible force.
25:04Thousand-tonne ice boulders were tossed about like dice.
25:15Alan's team have found the hole down which the lake disappeared
25:19and they want to have a closer look.
25:21It's not a job for anyone with a fear of heights.
25:30As you can see, it's dry up here, but if you listen,
25:33you can hear the thunder of...
25:35There's a lot of water entering it at some depth.
25:39Alan wants to place a sensor deep into the mooland
25:43to discover how much water is flowing through the ice.
25:52As they drop, they travel back in time.
25:5730 metres down and they reach ice formed from snow
26:01that fell 10,000 years ago in the last Ice Age.
26:07When this lake drained and the plug got pulled
26:11and the whole lot flushed down through here,
26:14this ice sheet, it rose by a metre
26:18as that water accessed the bed and force-jacked up the ice sheet.
26:22So we know that the water in this whole plumbing cavity system down here,
26:28we know that shoots straight through that ice
26:31and actually hits the bed of the ice sheet.
26:34We've hit the water. I can see the water now.
26:37Great. Nice work.
26:42This daring experiment is measuring how the water flowing under the ice sheet
26:47affects the speed with which the glaciers flow from it down to the sea.
26:52The theory is that the water is acting as a lubricant,
26:55so the more water there is, the faster the glacier flows.
27:01To the naked eye, glaciers don't appear to move at all,
27:05but move they do.
27:08These unique time-lapse images were captured over the last four years.
27:24Through long observations,
27:26we now know that Greenland's ice is flowing down to the sea
27:30twice as quickly as it was 20 years ago.
27:35The speed of the glaciers affects our sea levels
27:38because when they reach the water, they break apart into icebergs.
27:43Occasionally, a real megaberg is born.
27:55This is the Storr Glacier in May 2010.
28:05The ice sheet is melting.
28:08The ice sheet is melting.
28:11The ice sheet is melting.
28:14The ice sheet is melting.
28:17The ice sheet is melting.
28:20The ice sheet is melting.
28:23The ice sheet is melting.
28:26The ice sheet is melting.
28:29The ice sheet is melting.
28:32The ice sheet is melting.
28:5675 million tonnes of ice
28:59sitting on land for thousands of years has broken away.
29:08Events like this have become increasingly common
29:11as Greenland's glaciers flow faster into the sea.
29:16Every single one of these icebergs
29:19raises the sea level a small amount.
29:23Scientists monitoring the ice sheet
29:25predict that Greenland might add as much as a half metre
29:28to world sea levels by the end of the century,
29:31enough to swamp many of the world's low-lying islands.
29:36The ice sheet is melting.
29:38The ice sheet is melting.
29:41The ice sheet is melting.
29:44Everything in the Arctic hates the low-laying islands.
30:09Ninety-nine per cent of the Arctic's freshwater ice
30:12is in Greenland.
30:13It's a big ice sheet, but it's just a drop in the ocean
30:16compared to that at the southern end of our planet.
30:28In Antarctica, there is ten times more ice,
30:33by far the largest concentration of ice on Earth.
30:37Our exploration of the Antarctic only began a little over a hundred years ago.
30:48The study of ice retreat here was unwittingly begun
30:52on an expedition led by the great early explorer, Ernest Shackleton.
31:00In 1916, the expedition was launched into the Antarctic.
31:05In 1916, after their expedition boat was crushed and sunk by ice,
31:10Shackleton and two companions set off to summon help in a tiny boat.
31:19They sailed over 800 miles across the Southern Ocean
31:22to the island of South Georgia, on the edge of the Antarctic.
31:30Near starving and dressed in rags,
31:32the three men walked across the ice sheet at the centre of the island,
31:36knowing there was a whaling base on the opposite coast
31:39where they could summon help.
31:48This team of Royal Marines is retracing the steps of that journey
31:53in tribute to Shackleton and his men.
31:57But for all their efforts, they can't exactly copy the Great Walk
32:01because the ice is not as it was.
32:07A number of South Georgia's glaciers were photographed by Shackleton's cameraman.
32:13Frozen planets saw a dramatic change when they returned 94 years later.
32:31Most of South Georgia's glaciers have shrunk since Shackleton's time.
32:36And most of that has happened
32:38since I first went to the Antarctic 30 years ago.
32:43I've been to South Georgia several times
32:45and seen how greatly the glaciers there have changed.
32:54This photograph of a glacier reaching right down to the sea
32:58This photograph of a glacier reaching right down to the sea
33:01was taken just six years before I first visited in 1981.
33:07Now that glacier has retreated by 400 metres away from the beach.
33:18Temperatures in South Georgia have risen sharply,
33:21but the Southern Hemisphere's most dramatic warming
33:24has happened a little further south.
33:28In recent years, stronger winds blowing over the Southern Ocean
33:32have brought warmer air to the 800-mile-long finger of land
33:36that forms the northern extremity of the Antarctic continent.
33:46Here on the Antarctic Peninsula,
33:48the changing wind patterns have driven temperatures up
33:51by nearly three degrees centigrade over the last 50 years,
33:55ten times the average rate of the rest of the planet.
34:05The rapid warming is having a big effect on the bird life.
34:25The Adelie penguin is the most southerly nesting of all penguins.
34:33And like the polar bear up in the north,
34:36their lives are dependent on the sea ice.
34:41Adelies spend their whole lives near ice.
34:45These birds have spent the winter feeding at the ice edge,
34:48but now it's spring and they've started a long trek
34:51over the frozen sea towards land.
34:56They're heading for areas of exposed rock
34:59where they gather to breed in colonies that can be over 100,000 strong.
35:26But it seems that Adelies don't find the conditions on the peninsula
35:31to their liking anymore.
35:35Seventeen years ago, when I was last in the Antarctic,
35:38there were large colonies of Adelie penguins
35:41all along the Antarctic Peninsula.
35:45Now, warming temperatures have meant less sea ice
35:50and Adelie penguin numbers are in decline.
35:55ADELIE PENGUINS
36:02Many colonies have been emptied fast.
36:09It may be that penguins are starving
36:12or it may be that they're heading south to colder climes
36:15where there's still plenty of ice on the sea.
36:26But, as in the Arctic,
36:29while ice-loving animals are feeling the heat,
36:32animals that like it a bit more cosy are moving in.
36:43The bright orange beaks of Gentoo penguins
36:46are a much more common sight on the peninsula these days.
36:50I always used to know them as residents of the slightly warmer islands
36:54north of the Antarctic, but they've moved south in numbers.
37:00There are thought to be ten times more Gentoos on the peninsula now
37:03than just 30 years ago.
37:14The peninsula has warmed a great deal,
37:17but the same is not true further south.
37:25The Antarctic continent is smothered by the world's greatest ice sheet.
37:31One and a half times the size of Australia and up to three miles thick.
37:38A staggering 75% of the Earth's freshwater is locked up in this ice.
37:49Global sea levels would rise by some 60 metres
37:52if all this was to melt.
37:58But what chance is there of that happening here
38:01in the coldest, most hostile place on Earth?
38:10The ice beneath me, up here on top of the ice cap,
38:14is so thick that I am short of breath
38:18simply because of the altitude.
38:20This is midsummer,
38:23and the average temperature is some 20 degrees below freezing.
38:29And I can tell you, it feels much lower than that.
38:34And even the worst predictions don't suggest
38:38that the air is going to warm enough to melt the ice.
38:43But now scientists are asking a different question.
38:47Could the speed at which the Antarctic ice flows off the land
38:52be increased by a warmer ocean?
38:57Where the ice sheet meets the sea,
38:59scientists are going to extreme lengths to find out.
39:02Firing!
39:04Firing!
39:15Andy Smith works for the British Antarctic Survey.
39:20What we have here is one kilogram of pentahyte explosive.
39:24We're going to use this to generate a shockwave
39:27and record the echoes that come back from underneath the ice.
39:30Firing!
39:34Andy is particularly interested in mapping the underside of the ice
39:39around the coast.
39:42Because here it isn't resting on land.
39:45It's floating on seawater.
39:47So if sea temperatures rise just a little,
39:50it can be melted from below.
39:55Around the coast of Antarctica,
39:57the glaciers have flowed out across the sea
39:59to form immense masses of floating freshwater ice
40:03called ice shells.
40:09These freeze to the land around them,
40:11sticking fast and acting like bath plugs,
40:14holding back the flow of the glaciers into the sea.
40:20On the Antarctic Peninsula, a one-degree sea temperature rise
40:24has helped to break apart seven major ice shelves in the last 30 years.
40:30This is the Larsen B ice shelf,
40:33three times the size of Greater London, breaking apart in 2002.
40:40Afterwards, the glaciers it had been holding back
40:43started flowing up to six times faster.
40:49In 2008, a much larger ice shelf
40:52at the southern end of the peninsula started to break up.
40:56It's an enormous event that's never been filmed before.
41:03Andy Smith is flying down the peninsula to study this phenomenon firsthand.
41:09We're flying to a place called Wilkins Ice Shelf.
41:13It's an ice shelf that, over the last couple of years,
41:16has showed a very sudden and dramatic breakup.
41:21The Wilkins Ice Shelf is a two-hour-long flight south from his research base,
41:26but Andy can start to see the evidence of ice shelf breakup
41:29a long way before he gets there.
41:32As we're heading further south,
41:34we can see more and more icebergs in the ocean,
41:36and most of the big ones will be ones that have broken off the ice shelves
41:40in this area.
41:42Once we cross the mountains, we should be able to see Wilkins Ice Shelf,
41:45and then it's not far then to the ice front here where it's collapsing.
42:00As Andy's team reaches their destination,
42:03they're faced with the challenge of how to get to Wilkins Ice Shelf.
42:07As Andy's team reaches their destination,
42:11the scale of what's been happening soon becomes clear.
42:14Here, for thousands of years, an area the size of Yorkshire
42:18has been covered by a sheet of ice 200 metres thick.
42:26But now, over half of that has broken apart.
42:37WILKINS ICE SHELF
42:44Andy has been studying Antarctic ice for 25 years,
42:48but even he is blown away by what he's seeing.
42:52Now, that is pretty awesome.
42:55That is remarkable.
42:57The edge of the ice shelf has just kind of disintegrated.
43:01Some of the big pieces look like they could be a mile or more in size.
43:07It's almost like a sort of a slow-motion explosion.
43:11It all pushes outwards very quickly.
43:21Every one of these huge icebergs will slowly drift out to sea.
43:31To study how fast that happens, Andy needs to get closer to the action.
43:37We're going to look around and see if we can find a place where we can land,
43:41but if we can, we'll be able to put on an instrument
43:43that will help us monitor the big icebergs that are breaking off
43:47as the ice shelf breaks up.
43:57Landing on an iceberg is another first for Andy's team.
44:07WILKINS ICE SHELF
44:15This satellite transmitter will help to track the continued breakup
44:20of this colossal ice shelf.
44:21WILKINS ICE SHELF
44:34The remainder of the Wilkins looks set to break apart soon.
44:42It's the latest ice shelf to disintegrate
44:45in a wave that's been travelling southwards,
44:48playing a major role in the loss of ice from the peninsula.
44:52Next in line, and already weakening in places,
44:57are the ice shelves that hold back Antarctica's gigantic continental ice sheet.
45:04And it would only take a small corner of this to slide into the sea
45:08to have major global consequences.
45:14We've only started to see changes in the Arctic and Antarctic recently,
45:18so it's hard to predict exactly what impact these changes will have,
45:23but we can see for ourselves that these places are changing
45:26and on a scale that is hard to ignore.
45:32The poles, north and south, may seem very remote,
45:37but what is happening here is likely to have a greater effect upon us
45:42than any other aspect of global warming.
45:45If the Arctic sea ice continues to disappear,
45:49it will drive up the planet's temperature more quickly,
45:53and the melting ice sheets could contribute to a sea level rise of a metre,
45:58enough to threaten the homes of millions of people
46:01around the world's coasts by the end of the century.
46:06We've seen that the animals are already adapting to these changes,
46:11but can we respond to what is happening now to the frozen planet?
46:42THE CHANGES THAT WILL HAPPEN TO THE ICE
46:54The increasing unpredictability of the ice
46:57was a big issue for the Frozen Planet team,
47:00who spent three years working on top of it.
47:02THE CHANGES THAT WILL HAPPEN TO THE ICE
47:10Whether on sea, land, lake or river,
47:13the state of the ice was the first concern for most filming crews.
47:23Unexpected break-ups left many a cameraman in need of a swift rescue.
47:28Sometimes help came by boat and sometimes by air.
47:33THE CHANGES THAT WILL HAPPEN TO THE ICE
47:39I had a chance to see the changing ice conditions for myself
47:43when I visited the North Pole.
47:48I flew with the team to a temporary camp
47:51that is set up every year in the centre of the frozen Arctic Ocean
47:55to support expeditions to the pole.
47:57THE CHANGES THAT WILL HAPPEN TO THE ICE
48:02I had never visited the North Pole before,
48:04so this was a great highlight for me.
48:08But it was hard going in temperatures of minus 40,
48:11so as soon as filming finished, we flew south.
48:16Little did we know that we had made it out just in time.
48:21We got back from the pole camp last night
48:25and I've just bumped into the Russian commander,
48:28who's just heard from the camp.
48:30And the news is that a little crack which I'd seen in the ice
48:34between our tent and the airstrip,
48:38which was no more than an inch or so wide,
48:40has overnight widened to 20 metres.
48:45Temporary break-ups caused by stormy weather and strong winds
48:49have happened before,
48:50but they've been getting more and more frequent over recent years
48:54as the ice has got weaker.
49:00It was only swift action by the staff
49:02that prevented a lot of valuable equipment going in the drink.
49:13The biggest concern was that the ice airstrip might break apart,
49:17but luckily it held
49:18and everyone was able to evacuate when the weather improved.
49:25The Frozen Planet team's clearest demonstration
49:28of the power and unpredictability of breaking ice
49:31came when they went to film the melting of a frozen Canadian river.
49:35Producer Mark Linfield and researcher Matt Swarbrick
49:38have travelled to the far north of Canada.
49:41Matt, when was the last time we saw a car?
49:43I don't know, about three hours ago?
49:48They've driven through the vast Northwest Territory
49:50on a mission to film the melting of the ice.
49:54It's the moment when this frozen waterfall breaks apart.
50:00The break-up, when the frozen river above the waterfall thaws
50:04and masses of water start to flow again,
50:06can be a spectacular event,
50:09but predicting exactly when it's going to break
50:11is the big challenge if Mark and Matt want to get the best shots.
50:18And they're not the only ones who want to know.
50:21When the waterfall breaks,
50:22it can flood the town of Hay River just downstream
50:25with millions of tonnes of water and ice.
50:29Mark is taking advice from the scientist Faye Hicks,
50:32who has the job of predicting when the ice will break.
50:36What happens is you get ice jams form upstream
50:38and they start to dam up the water and it builds and builds and builds
50:41and that can let go and that's a much bigger wave of water
50:45than just the normal flow.
50:47So it just depends upon how dramatically it unfolds.
50:51Faye takes her research helicopter
50:53to monitor the situation upstream of the waterfall.
51:06Just ten miles upriver, the ice is starting to break.
51:12The locals are concerned because huge amounts of water can build up
51:15if these ice chunks dam the river
51:17and that can lead to devastating flooding in the town.
51:21When the dams burst.
51:22Sound limits moving through there now.
51:25Yeah, I got you. I'm on your six.
51:26Using cameras and sonar to assess the state of the river,
51:30Faye makes her best guess of when this breakup will hit the waterfall
51:33just above the town.
51:34So now, guys, I think we have about 48 hours to go.
51:39Faye's prediction of the 24th of April is exciting news for the team.
51:47Upstream from here, it's already starting to melt
51:50and Faye thinks that we may only have another one or two days
51:54before this whole thing goes,
51:56which is almost impossible to imagine looking at it now,
51:59but that's what she says.
52:02With the breakup seemingly imminent,
52:04the team set up their cameras in anticipation.
52:09Over the next 48 hours, the weather warms to well above freezing,
52:13but there's no sign of the breakup.
52:15The team waits and waits and waits.
52:20The crew return to the town
52:22to get advice from the town's resident, Red McBrien.
52:26Mark is concerned that the crew have to return home soon,
52:29so he heads into town to get the advice of long-term resident Red McBrien.
52:35We just have to live with it and take whatever evasive action we can.
52:40Red has had 50 years of witnessing the power of the river.
52:44We're hoping that she may break up in two or three days.
52:48Oh, no, no, no, no. That's too soon.
52:50Oh, no, no.
52:52Boys, you're looking at seven or eight days before she breaks
52:57of any significance, eh?
53:00And if she breaks, she can jam and hold up.
53:05She can be...
53:07She'd be down here probably around the 5th or 6th of May.
53:13The townspeople are on tenterhooks.
53:16The townspeople are on tenterhooks, waiting for the big day.
53:20But another week goes by before anything starts to happen.
53:36Finally, it seems that things might be happening.
53:38We've just heard some cracks from upstream,
53:40so if we're lucky, we might get some action.
53:45Seven o'clock, which gives us two hours' light.
53:47Two hours' light. If it happens at night, we're going to miss the whole thing.
53:53Sure enough, the town is put on red alert
53:56that the river is about to break in the middle of the night.
54:01They've just called a full evacuation of the island where we're staying.
54:05If we don't move now, we're all going to be underwater
54:07and possibly get trapped here for a few days.
54:10The team have to move out and get up to the waterfall,
54:13hoping that it doesn't break before it's light enough to film.
54:22Luckily, the sun is up before the main event begins.
54:26That is a serious amount of ice coming around the corner.
54:30After weeks of waiting,
54:32sleeping giant of a river, we thought nothing was going to happen,
54:36and suddenly, look at this.
54:38This is what we're here for.
54:40Unbelievable. Absolutely unbelievable.
54:44Holy ****.
54:45How hard is it to stay on the edge of this?
54:48It's a lot harder than I thought it was going to be.
54:50I'm not going to lie.
54:51I'm not going to lie.
54:53It's a lot harder than I thought it was going to be.
54:55It's a lot harder than I thought it was going to be.
54:57It's a lot harder than I thought it was going to be.
55:00The team is used to handling multiple cameras,
55:03but they don't usually have to dodge ten-tonne ice flows at the same time.
55:09You can see it's racing over at an unbelievable speed.
55:13The power, I just... If you were here to feel this,
55:16it's the deep rumbling sound of the river.
55:18I can feel it up through my feet.
55:20The power, I just can't imagine how you can crush a house in no time.
55:24The team takes to the air to witness the destruction that's unleashed.
55:29Huge ice blocks are pushed downstream
55:32on the wave of water released by the breaking waterfall.
55:39This could devastate the town.
55:46But this year, the townspeople's luck is in.
55:49The town has escaped flooding.
55:54Crucially, the ice blocks did not dam the river.
55:59It's running free.
56:01And the date of the break-up? 6th of May.
56:04Red's got it right again.
56:07I don't use any of these here gauges and mechanical assistance.
56:12I just go by what I see on the river as I walk it down.
56:17And I say I walk it down,
56:19I back and forth every day on the river to see what's happening,
56:23and from that, I gauge when it's going to hit here
56:27and what the situation's going to be like when it does get here.
56:31You know, when it went this morning, I said to my students,
56:34guess what the date is? Red told us it's the 6th of May.
56:36And I'm not surprised because we've been here a couple of times
56:39and that's happened.
56:41Ten days, two weeks out, he just looks around and goes,
56:435th of May.
56:45How does he know that? It's incredible.
56:47And it's because he just has lived on this river
56:49and lived this break-up for 50 years.
56:54Ice scientists are improving the accuracy of their predictions all the time,
56:59but in the meantime, the people of Hay River have a remarkable guardian.
57:04Red, you were completely right this year.
57:06Are you right every year?
57:08No, I'm...
57:10I missed the odd one.
57:13Yes. 1985, I missed it.
57:49Yes, I missed it.
57:51I missed it.
57:54I missed it.
57:56I missed it.
57:58I missed it.
58:00I missed it.
58:02I missed it.
58:04I missed it.
58:06I missed it.
58:08I missed it.
58:10I missed it.
58:12I missed it.
58:14I missed it.
58:16I missed it.