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00:00The power of the sun drives the seasons, transforming our planet.
00:13Vast movements of ocean and air currents bring dramatic change throughout the year.
00:23And in a few special places, these seasonal changes create some of the greatest wildlife
00:29spectacles on Earth.
00:35Here in the Arctic each summer, the sun begins to melt the winter ice.
00:43Nearly three million square miles of ice will disappear.
00:50Opening up a narrow window of opportunity for millions of animals.
01:04For many, it's their best chance to feed and breed.
01:13But for polar bears, it's the hardest time of the year.
01:18They have to survive the greatest seasonal change on the planet.
01:45Here in the Arctic, the northern lights flicker across the sky.
01:55It's a land of continuous night, where temperatures plummet to minus 40.
02:10Polar bears are in their element, hunting for seals on the frozen sea.
02:18But the long night is coming to an end.
02:21In February, the sun rises for the first time in four months.
02:34In the coming weeks, the strength of the sun will power an enormous change.
02:40For now, its rays offer only a little warmth.
02:57Despite the sun's return, six million square miles of the planet's far north is still cloaked
03:03in ice.
03:08Deep snow covers the mountains.
03:21Even the sea is frozen solid many meters deep.
03:37Groups of ringed seals haul out through holes in the ice to bask in the weak sunlight.
03:45But they're vulnerable and have to keep a lookout.
03:49With the sea still frozen, it's easier for predators to get close, and the seal's greatest
03:54enemy is the polar bear.
04:02A mother bear and her four-month-old cub are hunting.
04:09Seals make up most of the bear's diet, and to find them, she must lead her youngster
04:14out onto the ice for the first time.
04:20Scientists, looking at how a changing climate is affecting bears, have fitted the female
04:28with a radio collar.
04:32The ice here is thinner, and she must spread her weight to avoid breaking through.
04:42For her cub, it's all just a game.
05:04By sticking close to mum, he'll learn how she hunts for seals, a critical lesson for
05:10his future survival.
05:17At this time of year, the frozen Arctic is empty of life, and only a few hardy residents
05:23can survive.
05:27For a female Arctic fox, the winter has been a time of hunger.
05:31Food is scarce, and she's had to wander far and wide, scavenging from the remains of bear
05:36kills.
05:50But her fortunes are changing.
05:53A dead reindeer is a lucky find.
05:58If no other scavengers come along, this could sustain her for the rest of the winter.
06:05With the sea frozen, polar bears are busy hunting.
06:26This bear has caught a seal.
06:28He waited for it to surface through a hole in the ice, and his patience has been rewarded.
06:36He must catch a seal about once a week, and this is the best hunting season.
06:41As long as there's sea ice, the bears won't go hungry, as walking on the ice is the easiest
06:46way for a bear to get close to a seal.
06:55But the ice will soon start to break up, and hunting will get harder.
07:00The calories the bear takes in now will have to see him through hard times ahead.
07:08For polar bears, it's the survival of the fattest.
07:16At this time of year, there are still only five hours of daylight.
07:20And as the sun rises higher, each day lasts 40 minutes longer.
07:32It's March, and with increasing sunlight, the first in a huge wave of migrants are arriving.
07:50Hundreds of seabirds are traveling north to reach the frozen coast.
08:01Huge flocks of little orcs and guillemots fly across many miles of ice from the nearest
08:07open water.
08:17Their destination is the still-frozen sea cliffs.
08:21It's an inhospitable place, but in a few weeks, everything here will change.
08:37It pays to be early, even though the snow has yet to melt.
08:41The first arrivals get the best nesting ledges and a head start.
08:47They have just 50 days from laying their eggs to raise their chicks.
09:00The Arctic's silent wilderness is coming to life.
09:16It's three months since the sun's return, and its power is growing daily.
09:23The air temperature rises slowly, and once above freezing, at long last, the melt begins.
09:53The melting snow feeds freshwater streams, which pour off the land.
09:59In just a few short days, the melt unveils a whole new landscape.
10:14The coastal cliffs now teem with nesting seabirds, and it's not long before they attract
10:38unwelcome attention.
10:41The fox's white winter coat has disappeared with the snow.
10:46Her new camouflage will allow her to change from scavenger to hunter.
10:52The short summer will be her best chance to raise a family.
11:10The snow may be disappearing from the land, but the sea ice has yet to melt.
11:27The coastline is still locked in ice.
11:36The islands of the Arctic are surrounded by thousands of miles of white frozen ocean.
11:44Because the sea ice is so thick, it won't begin to break up until the temperature stays
11:49above freezing for a number of days.
11:53Until then, few creatures can penetrate this icy barrier.
12:03The sun reflects from the white frozen sea, creating a desert of icy mirage.
12:24The bear can still walk on the ice to hunt for seals, but not for much longer.
12:30It's getting warmer by the day.
12:54The bear's world is about to melt away.
13:13It's now June, and the sun beats down 24 hours a day.
13:18The temperature remains constant above freezing.
13:22The frozen sea begins to melt.
13:27Pools form across the surface, absorbing more of the sun's heat, speeding the thaw.
13:43Sunlight penetrates the frozen surface, illuminating a strange world beneath the ice.
13:56The frozen barrier has split.
14:07Mysterious voices echo against the icy ceiling.
14:16And cracks or leads form at weak points, creating a pathway for new arrivals.
14:36Narwhal.
14:55Known as the Arctic unicorn because of their strange spiral tusks, narwhal are some of
15:01the most secretive and elusive animals in the world's oceans.
15:06The leads provide passage for thousands of these mysterious whales.
15:13Each summer, they travel 600 miles north, navigating through the ice to reach rich fishing
15:19grounds.
15:24More whales travel along the edge of the ice, where it meets the open sea, to search for
15:29the openings of leads.
15:44It's a hazardous journey.
15:46As mammals, they need air to breathe.
15:49And if the ice closes above them, they could suffocate.
16:14They're looking for holes in the ice where they can surface.
16:26A single breath will last them for 15 minutes.
16:32The further they travel, the harder it becomes to find holes in the ice.
16:45They snatch a breath and then travel on.
16:51But ahead, the ice forms an impenetrable barrier.
17:14The narwhal use their heads and their long tusks to break the ice and enlarge the breathing
17:20holes.
17:29For now, they've reached a dead end and must wait.
17:33The ice will need to melt further if they're to continue.
17:38All across the Arctic, the sea ice is beginning to retreat.
17:45The leads widen, forming tracts of open water.
17:48Wind and ocean currents shift the loosening ice, breaking it up.
17:56As the ice melts, thousands of miles of open ocean become accessible, providing a bonanza
18:03for millions of seabirds.
18:14In just four weeks, a colony of guillemots can devour one and a half million tons of
18:21Arctic fish.
18:29As the ice melts, their journey to their feeding grounds in the open sea shortens by the day.
18:41They gather at the edge of the retreating ice and dive to hunt for Arctic cod and capelin.
19:02The shoals are found 250 feet down in the murky depths, and the guillemots must hold
19:08their breath for nearly two minutes.
19:20With their crops stuffed with fish, they return to the colony to feed their hungry youngsters.
19:35With 24 hours of daylight, they go on fishing around the clock.
19:53Warmed by the sun and driven by winds and currents, the sea ice is now fragmenting.
20:05That is a big problem if you need the ice to hunt from.
20:11A polar bear can smell a seal from over a mile away, but the prey he depends on is hard
20:22to find in this constantly moving landscape.
20:33He must take to the water to navigate through the drifting maze of ice.
20:39Bears are excellent swimmers, but he's no match for a seal.
20:46As the ice melts, finding seals gets harder, and with more open water, it's easier for
20:52the seal to escape.
21:08The melt has caused a shift in power.
21:12Now it's advantage sealed.
21:25The bear's chance has slipped away, and his hunger grows.
21:39With the ice barrier broken, strange marine visitors begin to arrive.
22:03They've swum 600 miles to get here, and with the ice gone, they can make their way into
22:09the shallows of freshwater estuaries.
22:26Beluga whales.
22:35As more and more belugas arrive, a strange annual ritual begins.
22:43For belugas, this is a very special event.
22:56Violent thrashing against the riverbed loosens their year-old skin and rids them of unwelcome
23:02parasites they may have picked up on their journey.
23:18In fresh water, warmed by the strengthening sun, and with the smooth pebbles in the shallows
23:23to rub against, the whales whistle with pleasure.
23:52But the ice-free summer will be short.
23:55The whales can only enjoy their arctic spa for two weeks.
24:00Soon, the belugas must leave the shallows and make the most of what's left of the summer
24:06to hunt the shoals of arctic fish.
24:16It's early July, and at the bird cliff, the fox has caught a nesting former.
24:27She has a family now, eight tiny mouths to feed, and one bird is not enough to go round.
24:44The cubs bicker over their dinner.
24:46They're only three weeks old, and in just another two weeks, they'll have to be ready
24:51to fend for themselves.
24:58The winter ahead will be so harsh that only two of these eight cubs are likely to gain
25:04enough weight to survive.
25:07Their lives depend on every mouthful.
25:14When food is scarce, the most dominant cub will feed, and the smallest will go hungry.
25:32The seabirds have been working round the clock to keep their chicks fed and to prepare them
25:38for the first big challenge of their lives.
25:40If they're to escape the winter, they'll have to leave the cliffs right away and get far
25:45out to sea.
25:48But it's only been twenty days since they hatched, and their wings are still too weak
25:53for them to fly.
25:55So far, their feet have never left the ground, and there's only one way down to the safety
26:00of the sea, a thousand feet below.
26:20Reluctantly, the chicks take a few nervous steps towards the edge.
26:33Encouraged by a gentle nudge, he leaps into the unknown.
26:51Dad follows right behind him, reassuringly calling to his chick.
27:08He's made it.
27:32The landings may not be stylish, but at least they're on target.
27:52It's easy to misjudge the distance, and some fall short of the water.
27:57But even now, Dad sticks close by.
28:05He encourages his chick to take the last few steps towards the safety of the waves.
28:11But some chicks land a long way from the water.
28:23They're sturdy enough to survive the fall, but this is no place to be left alone.
28:41For the mother fox, it's easy pickings.
28:55With so many free meals falling from the sky, she runs from one kill to the next.
29:17The chicks will be jumping for only three days, so she must make the most of this bonanza.
29:24The survival of her own family depends on it.
29:55With more chicks than she can possibly carry, the mother fox has to be clever.
30:07What her family can't eat now, she buries.
30:10For the days ahead, she'll have a well-stocked larder, enough for all eight of her cubs.
30:25Their bellies now full at last, the cubs can relax in the sun.
30:42For the guillemot chicks that survive, the ordeal has only just begun.
30:47They must retreat south 600 miles beyond the reach of winter.
30:53But the youngsters can't fly yet, their wings aren't strong enough.
30:57So led by their parents, they'll have to swim.
31:15At the height of summer, even the permanent ice caps are touched by the power of the sun.
31:26Meltwater, channeled down from high on these ice caps, pours over a precipice where the
31:32ice meets the ocean.
31:35Along this 200-mile wall of ice, a thousand freshwater cascades plummet into the sea.
32:00As July draws on, the Great Melt reaches its peak.
32:11The greatest seasonal change on the planet has taken place.
32:29The sea ice that once extended all the way to the horizon is now open ocean.
32:38In just three months, the sun has won its battle with the ice.
32:46Over two and a half million square miles of ice has melted away, uncovering thousands
32:52of islands surrounded by open ocean.
32:55But in recent years, the scale of this melt has been growing.
33:02And for one animal, this is a critical issue.
33:22A mother bear and her adolescent cub rest on a fragment of sea ice.
33:29With the melt, they're forced to swim ever greater distances to hunt for seals.
33:39Their Arctic home is increasingly vulnerable to a changing climate, and this year there
33:44has been even less ice than normal.
33:53If future melts are as extreme as this one, bears like these may starve or drown, lost
34:00at sea.
34:09This is one of the last pieces of ice now adrift in the open ocean.
34:14The polar bear's icy world has melted away.
34:29For many others, the open water provides the greatest feast of the year.
34:35The narwhal have made it through the ice.
34:38They gather in bays where they can hunt for Arctic cod and squid.
34:55Here, they are joined by other ocean migrants.
35:03Bowhead whales.
35:07These 100-ton giants feed on millions of tiny plankton that flourish in the sunlit waters.
35:25The lugers have come for the rich fishing and rest on the surface between dives.
35:37Even on the seabed, there is plenty on the menu.
35:52Two tons of pulsating blubber forages for clams in the sediment.
35:59Walrus are year-round residents of the Arctic, following the ebb and flow of the ice.
36:07In the open summer waters, they can reach huge areas of the ocean floor,
36:11rich feeding grounds for these giant seals.
36:17They hoover up clams with their rubbery lips.
36:20A single walrus can eat up to 4,000 clams in one 10-minute dive.
36:27Bellies full, they come up for air.
36:46With the sea ice gone, the walrus haul out on dry land to rest.
36:53They're used to huddling together to keep warm,
36:57and even now that it's 12 degrees above freezing, they prefer to stick close together.
37:03In the warmth of the sun, the walrus begin to shed their old skin,
37:07and they spend hours scratching.
37:13Some places are harder to reach than others.
37:17These irritations make them bad-tempered, and arguments often break out.
37:38Spitting, stabbing, and bellowing, the walrus can be a threat.
37:44Spitting, stabbing, and bellowing aren't out any disagreements.
37:54All disputes settled, a peace of sorts returns once more.
38:06Digesting a belly full of clams generates a lot of wind,
38:11making walrus colonies very fragrant places.
38:34Fed by the abundant supply of guillemot chicks,
38:39all eight fox cubs seem to have boundless energy.
38:43Soon they will be ready to face the world without their mother.
38:57In just five weeks, she's raised her cubs, making the most of the short summer.
39:09The mother fox has won her race against time.
39:18Between June and July, the Arctic is the land of the midnight sun.
39:23An empty wilderness has been transformed.
39:39The once-frozen ocean is now bursting with life,
39:43as all the animals enjoy the summer feast.
39:47The once-frozen ocean is now bursting with life,
39:51as all the animals enjoy the summer feast.
40:17But polar bears aren't so fortunate.
40:23With no sea ice to hunt on, they're now trapped on dry land.
40:31A hungry bear will eat any food it can get its paws on,
40:35but polar bears are not so fortunate.
40:40A hungry bear will eat any food it can get its paws on,
40:44but for a meat-eater, a few scraps of dry lichen won't go far.
40:55It may have been four months since his last kill,
40:59and he won't find any seals here.
41:04If the yearly increase in the scale of the meadow
41:07If the yearly increase in the scale of the melt continues,
41:11more bears will starve.
41:13Two-thirds of the world's polar bears could vanish by 2050.
41:21The Great Melt has always been difficult for bears,
41:25but soon, surviving the summer may become impossible.
41:32The scale of the summer melt has changed over the last 30 years.
41:372007's melt broke all records.
41:42400,000 extra square miles of ice disappeared,
41:46the greatest melt ever recorded.
41:50The latest predictions suggest that the Arctic
41:53may be entirely ice-free in summertime within 20 to 40 years.
42:00By September, the sun's power begins to ebb.
42:04The summer comes to an end, and the Arctic empties of life.
42:10The last seabirds begin their long journey south,
42:13leaving only a few hardy residents behind.
42:21The fox cubs now face the changing season alone.
42:26Already, the first snow is beginning to fall.
42:30The full Arctic winter is just six weeks away.
42:45For hungry bears, safety is paramount.
42:50For hungry bears, six weeks may be too long to wait.
42:56The sea ice will not freeze properly
42:59till it reaches two degrees below.
43:02For now, it's still too warm.
43:06This ice is no use to the bears.
43:09They can't walk on it to hunt.
43:13The normally unsociable bears gather in groups,
43:16trapped on the shoreline.
43:22This is the time of year the male bears spar.
43:32The male bears are the most active in the Arctic.
43:37Only the biggest bears have the energy reserves to fight.
43:41After a summer without food, the bear systems are in low gear.
43:45These aerobics help warm them up
43:48in readiness for the winter hunting ahead.
43:51This is the time of year the male bears spar.
43:54Only the biggest bears have the energy reserves to fight.
43:57After a summer without food, the bear systems are in low gear.
44:00These aerobics help warm them up
44:03in readiness for the winter hunting ahead.
44:21How are you?
44:45It's late October, but still the sea hasn't frozen.
44:49For every degree rise in the average temperature,
44:54the summer melt is extended by a whole week.
44:57That's more bad news for polar bears.
45:10Smaller, younger bears don't have the energy of the big males.
45:14Each day they are without food, they lose nearly two pounds.
45:19Some have lost half of their body weight.
45:24These hungry bears must now rest in the snow and conserve energy.
45:30All they can do is wait.
45:44At last, the wind changes,
45:47blowing from the cold north across the sea.
45:51The air temperature plummets to 20 degrees below.
45:56It's now cold enough for ice crystals to form in the ocean.
46:00They knit together, forming a greasy layer of surface ice.
46:06This thickens into plates, which bump and collide in the swell,
46:10forming pancake ice.
46:18These pancakes lock together to form a continuous surface.
46:29At long last, the sea has frozen.
46:37Only now can the bears head out onto the sea ice to hunt for seals.
46:43But the new ice has a surprise in store.
46:47SEA ICE
47:03This season, for the first time ever recorded,
47:07even the winter ice is thinner.
47:10SEA ICE
47:15The ice here is too thin to climb out on,
47:18and he struggles to free himself.
47:39SEA ICE
48:03At last, safely on the firmer ice, he rolls in the snow to dry his fur.
48:10SEA ICE
48:23In November, the sun sets over the frozen north.
48:28It will not appear again for four months.
48:31SEA ICE
48:36The summer melt provides opportunities for millions of animals,
48:40but has now become a threat to the polar bear's very survival.
48:47This season, the bear has survived the greatest melt yet recorded,
48:53and made it through to the Arctic winter.
49:01SEA ICE
49:19The frozen Arctic Sea is one of the most demanding of all environments,
49:24and the location for a rarely seen spectacle.
49:28The nature's great events team wanted to film the annual migration
49:33of the elusive Arctic narwhal.
49:37To do so, they would have to live on, dive beneath and fly over the ice
49:42during the climax of the great melt.
49:45SEA ICE
49:55The quest for the narwhal started at the height of the melt in July,
49:59when the sea ice was at its most dangerous.
50:02This made the task of first finding the whales a tough prospect.
50:11This is rough ice.
50:15And we're stuck.
50:18Narwhal are so elusive and the conditions working on the ice so difficult
50:22that the crew allowed a month to track them down.
50:26The plan was to get to the edge of the ice
50:29in the hope of finding the whales at the beginning of their migration.
50:37The melt was in full swing, and the team were in the thick of it.
50:43With 24 hours' sunlight,
50:46the leads along which the narwhal migrate were getting wider every day.
50:59After three weeks of searching,
51:01the whales were living up to their secretive reputation.
51:13The crew couldn't see the narwhal,
51:16but there was evidence that they were not far away.
51:19A sensitive hydrophone enabled them to eavesdrop on the whales under the ice.
51:29I am hearing what could be cetacean whistles and clicks,
51:33so it could be narwhal.
51:35It's very distant, and the sound travels one way underwater,
51:38so these guys are probably still far away, but it's a good sign.
51:43They could hear the whales, but would they be able to see them?
51:49By now, the cracks had opened wide enough for them to dive to search for them.
51:56Ice diving is dangerous at the best of times,
51:59but in such a remote location, days away from the ocean,
52:04they had to be especially careful.
52:11Even though it was the height of the summer,
52:13the icy seawater was still a chilly 30 degrees.
52:18So the team needed not only specialist equipment,
52:21but specialist attitude.
52:25You were very quiet there, Tom.
52:26Well, I was just thinking we don't really want the ice to close up
52:29while we're underneath it.
52:31No, closing up would be a bad thing.
52:32It would be a bummer.
52:34And Tom from Florida was taking no chances against the cold.
52:42That feels really good.
52:46See, we've got to do this more often.
52:48Yeah, hurry.
53:01Now they were in the whales' realm.
53:06A vast underworld of frigid water enclosed beneath a ceiling of ice.
53:16This is a world we rarely see.
53:18Sinister, but at the same time, uniquely beautiful.
53:31As the melting ice runs into the open cracks,
53:34it creates an underwater mirage
53:36as the layer of freshwater mixes with the denser saltwater beneath it.
53:47If the ice were to close in on them now, they could get trapped.
53:53As they ventured deeper,
53:55the crew carried a lifeline to the surface
53:57to guide them back to their opening in the ice.
54:22Sadly, there were no narwhal to be seen,
54:25but it was a unique glimpse
54:27of the whales' world.
54:30Sometimes it's a little bit spooky to have a ceiling above your head,
54:34and then when the tank starts breaking through a little bit,
54:37once in a while you think,
54:39it's really an intelligent thing to be doing,
54:41but the shot looked cool, so I think it was worth it.
54:48They had spent over a month on and under the sea ice,
54:53but with still no shots of narwhal,
54:55time and ice were running out.
54:59The edge of the ice was now only six inches thick,
55:03barely enough to support the weight of a man,
55:05let alone a camera team.
55:11You can feel the swell just coming up underneath this ice.
55:13It's pretty trippy.
55:15It's just a gentle undulation all around.
55:18This won't be here tomorrow.
55:25But just as the ice was getting too thin,
55:28their effort was rewarded.
55:31What do you see, Sam? Narwhal.
55:34See where the five guillemots are out there on the water?
55:37Six guillemots.
55:40Tom and his team had found the narwhal.
55:43The whales had arrived at long last.
55:46But, sadly, the ice was now too dangerous to film from.
55:52If they were to stand any chance of continuing to film,
55:56it was Tom and his team who would have to do it.
55:59The ice was too thick,
56:01and the water was too cold to swim through.
56:04The ice was too thick,
56:06and the water was too cold to swim through.
56:09It was time to call for reinforcements.
56:21After being stranded for seven days due to bad weather,
56:24the helicopter crew finally arrived just in time.
56:31There was now one last chance to film the narwhal.
56:35From the air.
56:38Armed with an advanced aerial camera system,
56:41they could zoom in on the action from a long distance away.
56:44This would enable them to find the whales
56:47and even get close-up shots without disturbing them.
56:55As the ice team headed home, the helicopter team took over.
56:59The helicopter could only carry enough fuel for a few hours flying,
57:04and finding the whales in this vast landscape was a daunting task.
57:10But, at last, they caught up with the magical Arctic unicorn.
57:16Yeah, there they are. They're kind of ten o'clock from me.
57:19Just coming under us now.
57:29Yeah.
57:37Nice. That's an amazing image. Beautiful.
57:47Unaware of the helicopter flying high above,
57:52the whales carried on their journey through the ice.
57:55This is the first time the narwhal migration
57:58has been filmed from this incredible aerial perspective.
58:10The plan had worked.
58:12It had taken over six weeks,
58:14but the team had managed to film the amazing journey of the narwhal
58:18in this most harsh and testing of landscapes.
58:23It was a rare and magical insight
58:26into the life of one of our planet's most mysterious creatures.
58:53The Arctic Unicorn
58:56The Arctic Unicorn
58:58The Arctic Unicorn
59:00The Arctic Unicorn
59:02The Arctic Unicorn
59:04The Arctic Unicorn
59:06The Arctic Unicorn
59:08The Arctic Unicorn
59:10The Arctic Unicorn
59:12The Arctic Unicorn
59:14The Arctic Unicorn
59:16The Arctic Unicorn
59:18The Arctic Unicorn
59:20The Arctic Unicorn