0:00:29 > 0:00:34This white wilderness, this emptiness, is the North Pole.
0:00:35 > 0:00:39I'm standing in the middle of a frozen ocean.
0:00:40 > 0:00:45Beneath my feet and for over 500 miles in every direction,
0:00:45 > 0:00:48there are several metres of ice.
0:00:49 > 0:00:52But something significant is likely to happen here,
0:00:52 > 0:00:54at the North Pole, soon.
0:00:56 > 0:00:59Chances are that some time, within the next few decades,
0:00:59 > 0:01:05perhaps even as soon as 2020, there will be open water here
0:01:05 > 0:01:09for the first time in human recorded history.
0:01:11 > 0:01:16The Arctic and Antarctic are changing.
0:01:16 > 0:01:20Enormous masses of ice that have been frozen for thousands of years
0:01:20 > 0:01:22are breaking apart and melting away.
0:01:35 > 0:01:40Ice scientists are going to extremes to find out exactly
0:01:40 > 0:01:41what's going on.
0:01:41 > 0:01:44For them, these are exciting times.
0:01:45 > 0:01:48But the transformation that's being seen here will be felt
0:01:48 > 0:01:50far beyond the polar wilderness.
0:01:57 > 0:01:58In this programme,
0:01:58 > 0:02:03I'll be trying to understand what these changes mean, not just to the
0:02:03 > 0:02:08wildlife and people that live around the Poles, but for the whole planet.
0:02:19 > 0:02:24I'm starting my journey in the Arctic, the far north of our planet.
0:02:28 > 0:02:31It's still very cold outside by most people's standards,
0:02:31 > 0:02:34but the Arctic has been warming fast,
0:02:34 > 0:02:37twice as fast as the rest of our planet.
0:02:37 > 0:02:41My first mission is to find out what effect
0:02:41 > 0:02:43that's having on the animals.
0:02:43 > 0:02:46Although first, we have to find them.
0:02:46 > 0:02:49It's April in Svalbard.
0:02:49 > 0:02:52We are 1,000 miles north of the Arctic Circle,
0:02:52 > 0:02:55in search of the region's top predator.
0:03:04 > 0:03:10We need to travel away from the land and out over the frozen sea.
0:03:17 > 0:03:19There's some tracks right beneath us.
0:03:25 > 0:03:26Over there.
0:03:29 > 0:03:32I'm with a Norwegian team,
0:03:32 > 0:03:36which is giving the polar bears of Svalbard their yearly health check.
0:03:40 > 0:03:41She's under us now.
0:03:42 > 0:03:44I'll come round for a clean shot.
0:03:50 > 0:03:53The team works together to give an anaesthetic injection
0:03:53 > 0:03:56from a dart gun without hurting the bear.
0:03:58 > 0:03:59It takes tremendous skill.
0:04:04 > 0:04:05Ah, you've got it.
0:04:10 > 0:04:13I'll just back off until she's asleep.
0:04:23 > 0:04:26Nobody likes to see a magnificent
0:04:26 > 0:04:30animal like a polar bear lolling about unconscious on the ice,
0:04:30 > 0:04:33but it's only by darting them
0:04:33 > 0:04:35in this way and keeping check on them
0:04:35 > 0:04:38year after year, that we can be sure we know
0:04:38 > 0:04:42what is happening to them and the population of polar bears as a whole.
0:04:43 > 0:04:47Over the last 30 years, many teams have been seeing
0:04:47 > 0:04:50the condition of their local bears deteriorate.
0:04:50 > 0:04:52Although not every bear is suffering.
0:05:02 > 0:05:05- How much?- 96, there.
0:05:05 > 0:05:10And 102 here, so that's 197, yeah.
0:05:10 > 0:05:11Is that good?
0:05:13 > 0:05:16It's not too bad, it's a bit above average.
0:05:16 > 0:05:19So she's a bear in a good condition for Svalbard.
0:05:19 > 0:05:25The trouble is that if this was underweight, she would be in trouble.
0:05:25 > 0:05:30Not only from her own point of view, but from the point of her cubs,
0:05:30 > 0:05:34because an underweight female gives birth to underweight cubs
0:05:34 > 0:05:38and underweight cubs have a great problem of surviving
0:05:38 > 0:05:41their difficult first year in these circumstances.
0:05:43 > 0:05:48It can be minus 40 degrees Centigrade when polar bear cubs emerge
0:05:48 > 0:05:50at the start of the Arctic spring,
0:05:50 > 0:05:52from their dens where they were born.
0:06:05 > 0:06:07This mother hasn't eaten for half a year.
0:06:10 > 0:06:14She and her cubs need to fatten up fast over the next few months and
0:06:14 > 0:06:18their chances of survival depend on what's happening beneath their feet.
0:06:22 > 0:06:25These polar bears aren't walking on land.
0:06:25 > 0:06:29They're roaming across the frozen surface of the sea.
0:06:33 > 0:06:35And the bear's food lives under the ice.
0:06:49 > 0:06:53Ringed seals are hunted by polar bears.
0:06:54 > 0:07:00In fact, in some parts, polar bears eat almost nothing else.
0:07:00 > 0:07:05So, it's very understandable that this mother ringed seal...
0:07:06 > 0:07:10..who's looking at me now, should be a little apprehensive.
0:07:14 > 0:07:18That pup of hers is only about three or four days old...
0:07:20 > 0:07:25..and the pup won't be able to swim for another two or three days.
0:07:28 > 0:07:32Seals have good reason to be nervous around their holes.
0:07:32 > 0:07:35They need the holes to breathe when the sea is frozen,
0:07:35 > 0:07:37but this makes them easy to find.
0:07:39 > 0:07:45Polar bears can sniff out seal holes, even if they're covered in snow.
0:07:51 > 0:07:53Spring is the best hunting season.
0:07:56 > 0:07:59This mother's found a food store under the snow
0:07:59 > 0:08:02that was probably made by an Arctic fox.
0:08:04 > 0:08:06It's a time of plenty now,
0:08:06 > 0:08:09but the bear family need to make the best of it
0:08:09 > 0:08:12because the good times are about to come to an end.
0:08:17 > 0:08:19As the weather warms,
0:08:19 > 0:08:23the ice beneath the bears' feet starts to break up and then melt.
0:08:23 > 0:08:28And as the ice dwindles, so do the bears' chances of a successful hunt.
0:08:31 > 0:08:36Most of the ice is lost over these shallow coastal waters,
0:08:36 > 0:08:38where most of the seals live.
0:08:43 > 0:08:47It's now summer and these bears have a choice - take their chances
0:08:47 > 0:08:52on the shrinking ice floes, or make for the safety of the land.
0:08:57 > 0:08:59It's a case of sink or swim.
0:09:07 > 0:09:09Bears have always gone hungry in the summer,
0:09:09 > 0:09:12but the length of time when there's enough ice for them
0:09:12 > 0:09:16to go hunting is getting shorter and shorter, across much of the Arctic.
0:09:20 > 0:09:23This is hitting cubs particularly hard,
0:09:23 > 0:09:27because they can't survive for as long without feeding as their mother.
0:09:29 > 0:09:33Cubs that were born underweight are at the greatest risk.
0:09:43 > 0:09:46This mother and her cubs may well not get another meal
0:09:46 > 0:09:49until the sea freezes again in winter.
0:09:49 > 0:09:54There's not much to eat on land and the fact is that the longer the cubs
0:09:54 > 0:09:59have to wait until the ice returns, the more likely they are to die.
0:10:02 > 0:10:06Longer summers with no ice are probably the main reason why
0:10:06 > 0:10:09many polar bear populations are dropping.
0:10:17 > 0:10:21To help monitor bears into the future, this female is being fitted
0:10:21 > 0:10:24with a radio collar to track her movements.
0:10:28 > 0:10:31It's an extraordinary sensation to be
0:10:31 > 0:10:34so close to such a powerful animal.
0:10:34 > 0:10:38With luck, carrying that collar,
0:10:38 > 0:10:40she will have more years to go yet...
0:10:41 > 0:10:44..and be telling us a great deal
0:10:44 > 0:10:46about herself and the rest
0:10:46 > 0:10:49of the race of polar bears, as they
0:10:49 > 0:10:51face this very uncertain future.
0:10:59 > 0:11:02The future of the ice cover on the sea isn't just
0:11:02 > 0:11:03an issue for the animals.
0:11:03 > 0:11:06It's a big concern for the people
0:11:06 > 0:11:07who live in the Arctic
0:11:07 > 0:11:10and travel across the ice every day.
0:11:18 > 0:11:23David Iqaqrialu is an Inuit from the village of Clyde River
0:11:23 > 0:11:24in the Canadian Far North.
0:11:30 > 0:11:35There are very few roads up here, so David and his community,
0:11:35 > 0:11:39like most Inuit people, have always travelled across the frozen sea.
0:11:41 > 0:11:45Dog sleds are the safest way to get around because the dogs feel
0:11:45 > 0:11:48thin ice underfoot and won't lead travellers into trouble.
0:11:52 > 0:11:54Old-timers, like David, know the ice is as well as we know
0:11:54 > 0:11:57the streets in our local neighbourhood.
0:12:01 > 0:12:02Every spring,
0:12:02 > 0:12:06cracks have always formed in the same places at the same time.
0:12:07 > 0:12:12It's going to be big very soon. After two weeks maybe...
0:12:13 > 0:12:16..it will be more open.
0:12:17 > 0:12:21But now, cracks are appearing where they never did before.
0:12:21 > 0:12:25So, David and his friend, Laimikie, have taken on a new job.
0:12:27 > 0:12:30They are using special GPS units to record the position
0:12:30 > 0:12:33of new cracks or weak ice.
0:12:35 > 0:12:37These findings will be used
0:12:37 > 0:12:39by locals for their own safety,
0:12:39 > 0:12:41but they're also being studied by ice scientists,
0:12:41 > 0:12:46who want to predict how the ice will change in years to come.
0:12:46 > 0:12:49THEY SPEAK THEIR NATIVE LANGUAGE
0:12:53 > 0:12:58The Inuit are keen to know what the future holds too
0:12:58 > 0:13:00because they've seen with their own eyes the changes
0:13:00 > 0:13:03that the scientists have seen from space.
0:13:05 > 0:13:08This satellite photo from 1980 shows the Arctic Ocean
0:13:08 > 0:13:13at the end of the summer, when ice cover is at its minimum.
0:13:13 > 0:13:17Since then, there's been a 30% drop in the area covered by ice.
0:13:20 > 0:13:25But these images can't tell us about changes to the most important factor,
0:13:25 > 0:13:27the thickness of the ice.
0:13:31 > 0:13:33Measuring thickness across the whole ocean
0:13:33 > 0:13:36was beyond scientists for many years,
0:13:36 > 0:13:40until help came from an unexpected source.
0:13:57 > 0:14:01The Arctic Ocean is of huge military importance, as it's the shortest
0:14:01 > 0:14:03route between North America and Russia.
0:14:09 > 0:14:14Since the late 1950s, British, US and Russian submarines
0:14:14 > 0:14:17have been patrolling the Arctic Ocean.
0:14:18 > 0:14:23But as well as looking out for enemy activity,
0:14:23 > 0:14:26they've also been measuring the thickness of the ice,
0:14:26 > 0:14:28critical when looking for a place to surface.
0:14:32 > 0:14:35When scientists got permission to look at the submarine crew's records,
0:14:35 > 0:14:39they discovered that the ice has been thinning fast.
0:14:39 > 0:14:42In fact, it's nearly halved in thickness since 1980.
0:14:47 > 0:14:49Across most of the Arctic Ocean,
0:14:49 > 0:14:52there are now just a couple of metres of ice.
0:14:56 > 0:15:01It's so thin that it could melt away almost entirely in the summertime,
0:15:01 > 0:15:03and that includes the ice at the North Pole.
0:15:05 > 0:15:08If current trends continue, then there will be
0:15:08 > 0:15:10open ocean here by summer's end,
0:15:10 > 0:15:12some time within the next few decades.
0:15:15 > 0:15:19So, the days of the Arctic Ocean being covered
0:15:19 > 0:15:22by a continuous sheet of ice seem to have passed.
0:15:22 > 0:15:25Whether or not that's a good or bad thing, of course,
0:15:25 > 0:15:27depends on your point of view.
0:15:30 > 0:15:33Nobody has had a better view of the changes to the Arctic Ocean
0:15:33 > 0:15:38than the people of Barrow, the most northerly town in Alaska.
0:15:38 > 0:15:42The people here have always survived by hunting on the frozen sea
0:15:42 > 0:15:44and they celebrate this at a festival every year.
0:15:47 > 0:15:50The blanket toss was once the best way to spot distant animals to hunt,
0:15:50 > 0:15:55as lifelong resident Lewis Brower explains.
0:15:55 > 0:15:58When we throw ourselves up into the blanket, you know,
0:15:58 > 0:16:02you get that much more of an 'Ahh' of seeing further and further out,
0:16:02 > 0:16:05so sometimes, you'll jump 15-20 feet in the air,
0:16:05 > 0:16:08and hopefully, you're being caught right back into the blanket.
0:16:10 > 0:16:12- I'm OK! - THEY LAUGH
0:16:14 > 0:16:16But the old way of life is under threat.
0:16:16 > 0:16:21When Lewis was young, the sea stayed frozen to the horizon until July,
0:16:21 > 0:16:24and some ice remained off-shore all summer.
0:16:24 > 0:16:26But now, it's breaking up in June
0:16:26 > 0:16:30and melting away completely for two or three months.
0:16:30 > 0:16:34I used to go out on the ice all the time at this time of the year,
0:16:34 > 0:16:39but we can't do that any more, cos there's no more ice.
0:16:41 > 0:16:45Lewis can also see that the loss of sea ice is affecting
0:16:45 > 0:16:47the animals he hunts for a living.
0:16:49 > 0:16:52Since 2007, something very strange has been happening
0:16:52 > 0:16:56on this stretch of coastline, close to Barrow.
0:16:59 > 0:17:04Mother walruses, confused by the lack of ice, are crowding onto the land
0:17:04 > 0:17:05with their pups.
0:17:07 > 0:17:09This very tight crowding isn't normal
0:17:09 > 0:17:12and it's caused many youngsters to be crushed to death.
0:17:15 > 0:17:18Many Arctic animals are threatened by the changing conditions
0:17:18 > 0:17:23and that's also bad news for the traditional hunters.
0:17:23 > 0:17:27But the ice loss could be good news for some people.
0:17:31 > 0:17:33There are trillions of dollars' worth of oil
0:17:33 > 0:17:35and gas under the Arctic Ocean.
0:17:35 > 0:17:37But the only way to get to them,
0:17:37 > 0:17:42until now, has been by building expensive artificial islands,
0:17:42 > 0:17:43like this.
0:17:43 > 0:17:45But if the sea ice goes,
0:17:45 > 0:17:48it will be much easier to drill for the huge riches below.
0:17:48 > 0:17:52So, the countries that surround the Arctic are scrambling
0:17:52 > 0:17:54to stake their claims.
0:18:05 > 0:18:10This daring attempt by the Russians to claim the disputed seabed
0:18:10 > 0:18:14at the North Pole in 2007 caused fury among the competing countries
0:18:14 > 0:18:17and it's unlikely to be the last such dispute.
0:18:19 > 0:18:22The Arctic has never been so important
0:18:22 > 0:18:25and not just because of its resources.
0:18:28 > 0:18:29The North-West Passage,
0:18:29 > 0:18:33a legendary sea route around the north of Canada and Alaska, cleared
0:18:33 > 0:18:38of ice in the summer of 2007 for the first time since records began.
0:18:38 > 0:18:41This promises a much faster
0:18:41 > 0:18:46and cheaper shipping route between the Atlantic and Pacific Oceans.
0:18:50 > 0:18:53And some wildlife could benefit from an ice-free Arctic too.
0:18:58 > 0:19:02Bowhead whales are one of just a few whales that can live
0:19:02 > 0:19:05year-round in the Arctic because they have no dorsal fin.
0:19:08 > 0:19:10This means they can come up for air in small spaces
0:19:10 > 0:19:13and travel easily under the ice.
0:19:14 > 0:19:18Their unique body shape used to mean that the Arctic whales had
0:19:18 > 0:19:22the seas to themselves for most of the year.
0:19:22 > 0:19:25But now, some cousins from down south are moving in.
0:19:32 > 0:19:36Killer whales are now a much more common sight in the Arctic.
0:19:36 > 0:19:40Their tall fins make it difficult for them to travel under ice,
0:19:40 > 0:19:44but the longer summers mean they can travel much further north
0:19:44 > 0:19:47and make the most of the rich Arctic seas.
0:19:54 > 0:19:57For animals and people,
0:19:57 > 0:20:00it will be those that can adapt who will thrive in a changing Arctic.
0:20:10 > 0:20:13But the loss of sea ice isn't just an issue for the Arctic,
0:20:13 > 0:20:17because the state of the ice affects the climate of the whole planet.
0:20:20 > 0:20:25Because it's white, the ice reflects up to 90% of the Sun's energy.
0:20:25 > 0:20:28This is called the albedo effect and it's why
0:20:28 > 0:20:33we often see heat haze in the Arctic, even when the air feels cold.
0:20:39 > 0:20:43The frozen Arctic Ocean acts as a huge reflector,
0:20:43 > 0:20:47bouncing back the Sun's heat into space.
0:20:47 > 0:20:50Throughout history, that has helped to cool the planet,
0:20:50 > 0:20:54but when the ice melts, it's a different story.
0:21:00 > 0:21:05Because sea water is dark, it absorbs most of the Sun's heat.
0:21:05 > 0:21:09In the Arctic, this can trigger a chain reaction, as the warming
0:21:09 > 0:21:14water melts more ice, exposing more water to the Sun's heat.
0:21:19 > 0:21:23This cycle of warming, as huge areas start to absorb rather than
0:21:23 > 0:21:27reflect heat, is the main reason why the Arctic, a region the size
0:21:27 > 0:21:32of North America, is warming twice as fast as the rest of the Earth.
0:21:37 > 0:21:40So, melting sea ice is a big issue.
0:21:40 > 0:21:43But there's another kind of ice that could have an even more
0:21:43 > 0:21:45dramatic impact on our world.
0:21:46 > 0:21:48The ice that is found on land.
0:21:51 > 0:21:53This is fresh water ice,
0:21:53 > 0:21:57formed from thousands of years of accumulated snowfall.
0:22:03 > 0:22:09This is the front of a glacier, quite a small one, believe it or not.
0:22:09 > 0:22:12Glaciers are like rivers of frozen
0:22:12 > 0:22:16fresh water flowing across the surface of the land.
0:22:16 > 0:22:19This one, like most polar glaciers,
0:22:19 > 0:22:23is flowing down from a vast inland ice sheet.
0:22:23 > 0:22:26And it's what happens to those ice sheets
0:22:26 > 0:22:30that could radically alter the face of the planet.
0:22:31 > 0:22:35The Greenland ice sheet is by far the largest in the Arctic.
0:22:35 > 0:22:37It's two miles thick in places
0:22:37 > 0:22:40and six times the size of the United Kingdom.
0:22:47 > 0:22:51Every summer, some of the surface of the ice sheet melts,
0:22:51 > 0:22:55forming sapphire-blue lakes of melt water.
0:22:56 > 0:22:59More and more of these lakes have been forming
0:22:59 > 0:23:02as Greenland has warmed over the last 20 years.
0:23:04 > 0:23:08This lake has grown over several weeks and now it's overflowing,
0:23:08 > 0:23:10carving a deep channel through the ice.
0:23:17 > 0:23:20A network of channels criss-crosses the ice sheet,
0:23:20 > 0:23:23but many of them come to an abrupt end.
0:23:34 > 0:23:38Huge holes, like this, can open up quite suddenly,
0:23:38 > 0:23:40draining the melt water away.
0:23:51 > 0:23:55Alun Hubbard is a glaciologist, studying the enormous power
0:23:55 > 0:23:59of these waterfalls, which are known as moulins.
0:23:59 > 0:24:04We've got this amazing moulin going off here today.
0:24:04 > 0:24:08The water's overflowing from the lake, which is beginning to drain.
0:24:08 > 0:24:14Tonnes of water cascading down this pipe that is, effectively,
0:24:14 > 0:24:18plummeting to the depths of the ice sheet through
0:24:18 > 0:24:20over a kilometre of vertical ice.
0:24:27 > 0:24:31Alun is here to study where the melt water goes
0:24:31 > 0:24:34and what effect it has on the remaining ice.
0:24:34 > 0:24:38To do that, he needs to find a moulin that has recently run dry.
0:24:44 > 0:24:47Just a week ago, there was a three-mile long,
0:24:47 > 0:24:50ten-metre deep lake here.
0:24:50 > 0:24:53The weight of all that water cracked the ice beneath
0:24:53 > 0:24:58and the late drained in just a few hours with incredible force.
0:25:03 > 0:25:07Thousand-tonne ice boulders were tossed about like dice.
0:25:14 > 0:25:17Alun's team have found the hole down which the lake disappeared
0:25:17 > 0:25:20and they want to have a closer look.
0:25:20 > 0:25:23It's not a job for anyone with a fear of heights.
0:25:30 > 0:25:32As you can see, it's dry up here, but if you listen,
0:25:32 > 0:25:34you can hear the thunder of,
0:25:34 > 0:25:37there's a lot of water entering it at some depth.
0:25:38 > 0:25:43Alun wants to place a sensor deep into the moulin to discover
0:25:43 > 0:25:45how much water is flowing through the ice.
0:25:51 > 0:25:54As they drop, they travel back in time.
0:25:56 > 0:26:0030 metres down and they reach ice formed from snow that fell
0:26:00 > 0:26:0310,000 years ago, in the last Ice Age.
0:26:06 > 0:26:11When this lake drained and the plug got pulled and the whole lot
0:26:11 > 0:26:17flushed down through here, this ice sheet, it rose by a metre
0:26:17 > 0:26:21as that water accessed the bed and forced, jacked up the ice sheet.
0:26:21 > 0:26:24So, we know that the water
0:26:24 > 0:26:28in this whole plumbing cavity system, down here,
0:26:28 > 0:26:30we know that shoots straight through that ice
0:26:30 > 0:26:33and actually hits the bed of the ice sheet.
0:26:33 > 0:26:36We've hit the water, I can see the water now.
0:26:36 > 0:26:38Great. Nice work.
0:26:41 > 0:26:45This daring experiment is measuring how the water flowing under
0:26:45 > 0:26:48the ice sheet affects the speed with which the glaciers
0:26:48 > 0:26:51flow from it, down to the sea.
0:26:51 > 0:26:55The theory is that the water is acting as a lubricant.
0:26:55 > 0:26:58So, the more water there is, the faster the glacier flows.
0:27:00 > 0:27:05To the naked eye, glaciers don't appear to move at all.
0:27:05 > 0:27:06But move they do.
0:27:08 > 0:27:12These unique time-lapse images were captured over the last four years.
0:27:25 > 0:27:29Through long observations, we now know that Greenland's ice
0:27:29 > 0:27:34is flowing down to the sea twice as quickly as it was 20 years ago.
0:27:34 > 0:27:37The speed of the glaciers affects our sea levels
0:27:37 > 0:27:42because when they reach the water, they break apart into icebergs.
0:27:44 > 0:27:46Occasionally, a real mega-berg is born.
0:27:55 > 0:27:58This is the Store Glacier in May 2010.
0:28:55 > 0:28:5875 million tonnes of ice, that had been sitting on land
0:28:58 > 0:29:01for thousands of years, has broken away.
0:29:06 > 0:29:09Events like this have become increasingly common,
0:29:09 > 0:29:13as Greenland's glaciers flow faster into the sea.
0:29:25 > 0:29:31Every single one of these icebergs raises the sea level a small amount.
0:29:31 > 0:29:36Scientists monitoring the ice sheet predict that Greenland might add
0:29:36 > 0:29:40as much as a half metre to world sea levels by the end of the century,
0:29:40 > 0:29:44enough to swamp many of the world's low-lying islands.
0:30:06 > 0:30:1199% of the Arctic's fresh water ice is in Greenland.
0:30:11 > 0:30:15It's a staggeringly big ice sheet, but it's just a drop in the ocean
0:30:15 > 0:30:19compared to that at the southern end of our planet.
0:30:27 > 0:30:32In Antarctica, there is ten times more ice,
0:30:32 > 0:30:35by far the largest concentration of ice on Earth.
0:30:40 > 0:30:43Our exploration of the Antarctic only began
0:30:43 > 0:30:45a little over 100 years ago.
0:30:51 > 0:30:55The study of ice retreat here was unwittingly begun
0:30:55 > 0:30:59on an expedition led by the great early explorer Ernest Shackleton.
0:31:03 > 0:31:08In 1916, after their expedition boat was crushed and sunk by ice,
0:31:08 > 0:31:14Shackleton and two companions set off to summon help in a tiny boat.
0:31:17 > 0:31:21They sailed over 800 miles across the Southern Ocean
0:31:21 > 0:31:24to the island of South Georgia, on the edge of the Antarctic.
0:31:28 > 0:31:32Near starving and dressed in rags, the three men
0:31:32 > 0:31:35walked across the ice sheet at the centre of the island, knowing there
0:31:35 > 0:31:39was a whaling base on the opposite coast where they could summon help.
0:31:47 > 0:31:51This team of Royal Marines is re-tracing the steps
0:31:51 > 0:31:54of that journey in tribute to Shackleton and his men.
0:31:56 > 0:32:01But for all their efforts, they can't exactly copy the great walk
0:32:01 > 0:32:02because the ice is not as it was.
0:32:06 > 0:32:08A number of South Georgia's glaciers
0:32:08 > 0:32:10were photographed
0:32:10 > 0:32:11by Shackleton's cameraman.
0:32:11 > 0:32:14Frozen Planet saw a dramatic change
0:32:14 > 0:32:17when they returned 94 years later.
0:32:35 > 0:32:40Most of South Georgia's glaciers have shrunk since Shackleton's time
0:32:40 > 0:32:41and most of that has happened
0:32:41 > 0:32:44since I first went to the Antarctic 30 years ago.
0:32:46 > 0:32:49I've been to South Georgia several times
0:32:49 > 0:32:52and seen how greatly the glaciers there have changed.
0:32:56 > 0:32:58This photograph of a glacier
0:32:58 > 0:33:00reaching right down to the sea
0:33:00 > 0:33:02was taken just six years
0:33:02 > 0:33:05before I first visited in 1981.
0:33:06 > 0:33:11Now, that glacier has retreated by 400 metres away from the beach.
0:33:16 > 0:33:21Temperatures in South Georgia have risen sharply, but the Southern
0:33:21 > 0:33:25Hemisphere's most dramatic warming has happened a little further south.
0:33:27 > 0:33:31In recent years, stronger winds blowing over the Southern Ocean
0:33:31 > 0:33:35have brought warmer air to the 800- mile-long finger of land that forms
0:33:35 > 0:33:39the northern extremity of the Antarctic continent.
0:33:45 > 0:33:49Here, on the Antarctic Peninsula, the changing wind patterns have driven
0:33:49 > 0:33:53temperatures up by nearly three degrees Centigrade
0:33:53 > 0:33:54over the last 50 years.
0:33:54 > 0:33:58Ten times the average rate of the rest of the planet.
0:34:04 > 0:34:09The rapid warming is having a big effect on the birdlife.
0:34:24 > 0:34:29The Adelie penguin is the most southerly nesting of all penguins.
0:34:32 > 0:34:35And like the polar bear up in the north,
0:34:35 > 0:34:38their lives are dependent on the sea ice.
0:34:40 > 0:34:43Adelies spend their whole lives near ice.
0:34:43 > 0:34:46These birds have spent the winter feeding at the ice edge,
0:34:46 > 0:34:48but now it's spring
0:34:48 > 0:34:53and they've started a long trek over the frozen sea towards land.
0:35:00 > 0:35:05They're heading for areas of exposed rock, where they gather
0:35:05 > 0:35:09to breed, in colonies that can be over 100,000 strong.
0:35:26 > 0:35:29But it seems that Adelies don't find the conditions
0:35:29 > 0:35:31on the peninsula to their liking any more.
0:35:33 > 0:35:3817 years ago, when I was last in the Antarctic, there were
0:35:38 > 0:35:43large colonies of Adelie penguins all along the Antarctic Peninsula.
0:35:43 > 0:35:49Now, warming temperatures have meant less sea ice
0:35:49 > 0:35:52and Adelie penguin numbers are in decline.
0:36:01 > 0:36:04Many colonies have been emptying fast.
0:36:08 > 0:36:10It may be that penguins are starving,
0:36:10 > 0:36:14or it may be that they're heading south to colder climes
0:36:14 > 0:36:17where there's still plenty of ice on the sea.
0:36:25 > 0:36:30But, as in the Arctic, while ice-loving animals are feeling
0:36:30 > 0:36:35the heat, animals that like it a bit more cosy are moving in.
0:36:43 > 0:36:46The bright orange beaks of Gentoo penguins are a much more common sight
0:36:46 > 0:36:49on the peninsula these days.
0:36:49 > 0:36:51I always used to know them as residents
0:36:51 > 0:36:55of the slightly warmer islands north of the Antarctic.
0:36:55 > 0:36:57But they've moved south in numbers.
0:36:58 > 0:37:02There are thought to be ten times more Gentoos on the peninsula now
0:37:02 > 0:37:04than just 30 years ago.
0:37:13 > 0:37:16The peninsula has warmed a great deal,
0:37:16 > 0:37:18but the same is not true further south.
0:37:23 > 0:37:28The Antarctic continent is smothered by the world's greatest ice sheet.
0:37:29 > 0:37:32One and half times the size of Australia
0:37:32 > 0:37:34and up to three miles thick.
0:37:37 > 0:37:42A staggering 75% of the Earth's fresh water is locked up in this ice.
0:37:47 > 0:37:53Global sea levels would rise by some 60 metres if all this was to melt.
0:37:57 > 0:38:01But what chance is there of that happening here in the coldest,
0:38:01 > 0:38:03most hostile place on Earth?
0:38:08 > 0:38:13The ice beneath me, up here on top of the ice cap, is so thick
0:38:13 > 0:38:18that I am short of breath, simply because of the altitude.
0:38:19 > 0:38:22This is midsummer
0:38:22 > 0:38:27and the average temperature is some 20 degrees below freezing.
0:38:28 > 0:38:31And I can tell you it feels much lower than that.
0:38:32 > 0:38:37And even the worst predictions don't suggest
0:38:37 > 0:38:42that the air is going to warm enough to melt the ice.
0:38:42 > 0:38:46But now, scientists are asking a different question.
0:38:47 > 0:38:52Could the speed at which the Antarctic ice flows off the land
0:38:52 > 0:38:54be increased by a warmer ocean?
0:38:55 > 0:38:58Where the ice sheet meets the sea,
0:38:58 > 0:39:01scientists are going to extreme lengths to find out.
0:39:01 > 0:39:02Firing!
0:39:14 > 0:39:17Andy Smith works for the British Antarctic Survey.
0:39:19 > 0:39:23What we have here is one kilogramme of pentolite explosive.
0:39:23 > 0:39:26We're going to use this to generate a shockwave
0:39:26 > 0:39:29and record the echoes that come back from underneath the ice.
0:39:29 > 0:39:31Firing.
0:39:34 > 0:39:37Andy is particularly interested in mapping
0:39:37 > 0:39:39the underside of the ice around the coast.
0:39:41 > 0:39:44Because here, it isn't resting on land.
0:39:44 > 0:39:48It's floating on sea water, so if sea temperatures rise
0:39:48 > 0:39:51just a little, it can be melted from below.
0:39:53 > 0:39:56Around the coast of Antarctica,
0:39:56 > 0:40:00the glaciers have flowed out across the sea to form immense masses
0:40:00 > 0:40:04of floating fresh water ice, called ice shelves.
0:40:08 > 0:40:12These freeze to the land around them, sticking fast and acting
0:40:12 > 0:40:16like bathplugs, holding back the flow of the glaciers into the sea.
0:40:19 > 0:40:24On the Antarctic Peninsula, a one-degree sea temperature rise
0:40:24 > 0:40:28has helped to break apart seven major ice shelves in the last 30 years.
0:40:30 > 0:40:32This is the Larsen B ice shelf,
0:40:32 > 0:40:36three times the size of Greater London, breaking apart in 2002.
0:40:39 > 0:40:42Afterwards, the glaciers it had been holding back
0:40:42 > 0:40:45started flowing up to six times faster.
0:40:48 > 0:40:52In 2008, a much larger ice shelf at the southern end
0:40:52 > 0:40:55of the peninsula started to break up.
0:40:56 > 0:40:59It's an enormous event that's never been filmed before.
0:41:02 > 0:41:04Andy Smith is flying down the peninsula to study
0:41:04 > 0:41:07this phenomenon first hand.
0:41:08 > 0:41:12We're flying to a place called Wilkins Ice Shelf.
0:41:12 > 0:41:15It's an ice shelf that, over the last couple of years,
0:41:15 > 0:41:19has shown a very sudden and dramatic break-up.
0:41:21 > 0:41:24The Wilkins Ice Shelf is a two-hour long flight south
0:41:24 > 0:41:28from his research base, but Andy can start to see
0:41:28 > 0:41:33the evidence of ice shelf break-up a long way before he gets there.
0:41:33 > 0:41:34As we're heading further south,
0:41:34 > 0:41:37we can see more and more icebergs in the ocean.
0:41:37 > 0:41:40And most of the big ones will be ones
0:41:40 > 0:41:42that have broken off the ice shelves in this area.
0:41:48 > 0:41:50Once we cross the mountains, we should be able to see
0:41:50 > 0:41:54Wilkins Ice Shelf and then it's not far then to the ice front, here,
0:41:54 > 0:41:55where it's collapsing.
0:42:07 > 0:42:10As Andy's team reaches their destination,
0:42:10 > 0:42:13the scale of what's been happening soon becomes clear.
0:42:13 > 0:42:17Here, for thousands of years, an area the size of Yorkshire
0:42:17 > 0:42:20has been covered by a sheet of ice 200 metres thick.
0:42:25 > 0:42:28But now, over half of that has broken apart.
0:42:42 > 0:42:47Andy has been studying Antarctic ice for 25 years,
0:42:47 > 0:42:50but even he is blown away by what he's seeing.
0:42:51 > 0:42:55Now, that is pretty awesome. That is remarkable.
0:42:55 > 0:42:59The edge of the ice shelf has just, kind of, disintegrated.
0:42:59 > 0:43:02Some of the big pieces look like
0:43:02 > 0:43:04they could be a mile or more in size.
0:43:06 > 0:43:10It's almost like a, sort of, a slow motion explosion.
0:43:10 > 0:43:12It all pushes outwards very quickly.
0:43:20 > 0:43:25Every one of these huge icebergs will slowly drift out to sea.
0:43:30 > 0:43:34To study how fast that happens, Andy needs to get closer to the action.
0:43:36 > 0:43:40We're going to look around and see if we can find a place where
0:43:40 > 0:43:42we can land. And if we can, we'll be able to put down an instrument
0:43:42 > 0:43:46that will help us monitor the big icebergs that are breaking off
0:43:46 > 0:43:47as the ice shelf breaks up.
0:43:55 > 0:43:59Landing on an iceberg is another first for Andy's team.
0:44:13 > 0:44:17This satellite transmitter will help to track the continued break-up
0:44:17 > 0:44:20of this colossal ice shelf.
0:44:33 > 0:44:38The remainder of the Wilkins looks set to break apart soon.
0:44:41 > 0:44:45It's the latest ice shelf to disintegrate in a wave that's been
0:44:45 > 0:44:47travelling southwards,
0:44:47 > 0:44:50playing a major role in the loss of ice from the peninsula.
0:44:51 > 0:44:57Next in line, and already weakening in places, are the ice shelves
0:44:57 > 0:45:02that hold back Antarctica's gigantic continental ice sheet.
0:45:03 > 0:45:07And it would only take a small corner of this to slide into the sea
0:45:07 > 0:45:09to have major global consequences.
0:45:12 > 0:45:17We've only started to see changes in the Arctic and Antarctic recently.
0:45:17 > 0:45:21So, it's hard to predict exactly what impact these changes will have.
0:45:21 > 0:45:25But we can see for ourselves that these places are changing
0:45:25 > 0:45:28and on a scale that is hard to ignore.
0:45:31 > 0:45:36The Poles, North and South, may seem very remote,
0:45:36 > 0:45:40but what is happening here is likely to have a greater effect upon us
0:45:40 > 0:45:44than any other aspect of global warming.
0:45:44 > 0:45:48If the Arctic sea ice continues to disappear,
0:45:48 > 0:45:53it will drive up the planet's temperature more quickly.
0:45:53 > 0:45:55And the melting ice sheets could contribute to a sea level rise
0:45:55 > 0:46:00of a metre, enough to threaten the homes of millions of people
0:46:00 > 0:46:03around the world's coasts by the end of the century.
0:46:04 > 0:46:09We've seen that the animals are already adapting to these changes,
0:46:09 > 0:46:16but can WE respond to what is happening now to the frozen planet?
0:46:53 > 0:46:57The increasing unpredictability of the ice was a big issue
0:46:57 > 0:47:02for the Frozen Planet team, who spent three years working on top of it.
0:47:09 > 0:47:12Whether on sea, land, lake or river,
0:47:12 > 0:47:17the state of the ice was the first concern for most filming crews.
0:47:22 > 0:47:28Unexpected break-ups left many a cameraman in need of a swift rescue.
0:47:28 > 0:47:31Sometimes, help came by boat, and sometimes by air.
0:47:38 > 0:47:42I had a chance to see the changing ice conditions for myself,
0:47:42 > 0:47:44when I visited the North Pole.
0:47:47 > 0:47:51I flew with the team to a temporary camp that is set up every year in
0:47:51 > 0:47:55the centre of the frozen Arctic Ocean to support expeditions to the Pole.
0:48:00 > 0:48:04I had never visited the North Pole before,
0:48:04 > 0:48:06so this was a great highlight for me.
0:48:07 > 0:48:10But it was hard going in temperatures of minus 40,
0:48:10 > 0:48:12so as soon as filming finished, we flew south.
0:48:15 > 0:48:18Little did we know that we had made it out just in time.
0:48:20 > 0:48:24We got back from the Pole camp last night and I've just bumped into
0:48:24 > 0:48:28the Russian Commander, who's just heard from the camp.
0:48:28 > 0:48:33And the news is that a little crack, which I'd seen in the ice
0:48:33 > 0:48:39between our tent and the airstrip, which was no more than an inch
0:48:39 > 0:48:43or so wide, has, overnight, widened to 20 metres.
0:48:43 > 0:48:47Temporary break-ups, caused by stormy weather
0:48:47 > 0:48:50and strong winds, have happened before, but they've been getting
0:48:50 > 0:48:54more and more frequent over recent years as the ice has got weaker.
0:48:59 > 0:49:02It was only swift action by the staff that prevented
0:49:02 > 0:49:05a lot of valuable equipment going in the drink.
0:49:12 > 0:49:16The biggest concern was that the ice airstrip might break apart,
0:49:16 > 0:49:19but, luckily, it held and everyone was able to evacuate
0:49:19 > 0:49:21when the weather improved.
0:49:25 > 0:49:29The Frozen Planet team's clearest demonstration of the power
0:49:29 > 0:49:32and unpredictability of breaking ice
0:49:32 > 0:49:36came when they went to film the melting of a frozen Canadian river.
0:49:36 > 0:49:38Producer Mark Linfield
0:49:38 > 0:49:42and researcher Matt Swarbrick have travelled to the far North of Canada.
0:49:42 > 0:49:44Matt, when was the last time we saw a car?
0:49:44 > 0:49:46I don't know, about three hours ago.
0:49:48 > 0:49:52They've driven through the vast Northwest Territory on a mission
0:49:52 > 0:49:55to film the moment when this frozen waterfall breaks apart.
0:49:59 > 0:50:03The break-up, when the frozen river above the waterfall thaws
0:50:03 > 0:50:07and masses of water start to flow again, can be a spectacular event.
0:50:07 > 0:50:10But predicting exactly when it's going to break
0:50:10 > 0:50:14is the big challenge, if Mark and Matt want to get the best shots.
0:50:16 > 0:50:19And they're not the only ones who want to know.
0:50:19 > 0:50:23When the waterfall breaks, it can flood the town of Hay River,
0:50:23 > 0:50:28just downstream, with millions of tonnes of water and ice.
0:50:28 > 0:50:31Mark is taking advice from scientist Fay Hicks,
0:50:31 > 0:50:35who studies the break-up of Canada's frozen rivers.
0:50:35 > 0:50:38What happens is, you get ice jams form upstream and they start to dam
0:50:38 > 0:50:39up the water and it builds
0:50:39 > 0:50:41and builds and builds, and that can let go,
0:50:41 > 0:50:44and that's a much bigger wave of water, you know,
0:50:44 > 0:50:46than just the normal flow.
0:50:46 > 0:50:49So, it just depends upon how dramatically it unfolds.
0:50:50 > 0:50:53Every spring, Fay travels to Northern Canada
0:50:53 > 0:50:56to study the way that breaking ice can jam rivers.
0:51:05 > 0:51:09The spring break-up is of great significance to the people of the far north.
0:51:10 > 0:51:14When the upper reaches of these rivers melt, huge amounts of water can build up
0:51:14 > 0:51:16behind dams of ice.
0:51:16 > 0:51:19When these dams burst, a surge of ice and water
0:51:19 > 0:51:23can cause devastation to settlements along the banks.
0:51:25 > 0:51:29Ground-penetrating radar provides information about the thickness of the ice,
0:51:29 > 0:51:32crucial to the study of the break-up.
0:51:32 > 0:51:38But predicting the date of the big day is notoriously hard.
0:51:38 > 0:51:41Fay has warned the team that events could unfold very quickly
0:51:41 > 0:51:43if conditions continue to warm.
0:51:47 > 0:51:52The crew start to prepare. The waterfall appears to be waking.
0:51:54 > 0:51:59There's a lot of work to do if they're to cover the break-up with as many cameras as possible.
0:52:06 > 0:52:09The weather continues to warm, but nothing happens.
0:52:13 > 0:52:18Far upstream, there's been a snowstorm, which is slowing down the break-up.
0:52:20 > 0:52:23The team waits and waits and waits.
0:52:27 > 0:52:30Mark is concerned that the crew have to return home soon, so
0:52:30 > 0:52:32he heads into town to get the advice
0:52:32 > 0:52:35of long-term resident Red McBrian.
0:52:35 > 0:52:41We just have to live with it and take whatever evasive action we can.
0:52:41 > 0:52:45Red has had 50 years of witnessing the power of the river.
0:52:45 > 0:52:49Well, we're hoping that she may break up in two or three days.
0:52:49 > 0:52:53Oh, no, no, no, that's too soon. Oh, no, no.
0:52:53 > 0:52:57Boys, you're looking at seven or eight days
0:52:57 > 0:53:02before she breaks of any significance.
0:53:02 > 0:53:08And if she breaks, she can jam and hold up. She can be...
0:53:09 > 0:53:13She'd be down here probably around the 5th or 6th May.
0:53:15 > 0:53:19The snowstorm has derailed the team's plans,
0:53:19 > 0:53:22and another week goes by before the river starts to move.
0:53:34 > 0:53:37Finally, it seems that things might be happening.
0:53:37 > 0:53:39We've just heard some cracks from upstream,
0:53:39 > 0:53:43so, if we're lucky, we might get some action.
0:53:43 > 0:53:47- Seven o'clock, which gives us two hours of light.- Two hours.
0:53:47 > 0:53:51If it happens at night, we're going to miss the whole thing.
0:53:52 > 0:53:55Sure enough, the town is put on red alert
0:53:55 > 0:53:59that the river is about to break in the middle of the night.
0:53:59 > 0:54:02They've just called a full evacuation of the Eye Inn,
0:54:02 > 0:54:05where we're staying, and if we don't move now, we're all going to be
0:54:05 > 0:54:08underwater and possibly get trapped here for a few days.
0:54:09 > 0:54:11The team have to move out and get up to the waterfall,
0:54:11 > 0:54:16hoping that it doesn't break before it's light enough to film.
0:54:21 > 0:54:24Luckily, the sun is up before the main event begins.
0:54:24 > 0:54:28That is a serious amount of ice coming around the corner.
0:54:39 > 0:54:43After weeks of waiting, the sleeping giant of a river,
0:54:43 > 0:54:47we thought nothing was go to happen and suddenly, look at this!
0:54:49 > 0:54:52This is what we're here for. Unbelievable.
0:54:52 > 0:54:55- Absolutely unbelievable. Holy- BLEEP!
0:54:59 > 0:55:01The team is used to handling multiple cameras,
0:55:01 > 0:55:05but they don't usually have to dodge ten-tonne ice floes at the same time.
0:55:09 > 0:55:11As you can see, it's racing over at unbelievable speed.
0:55:11 > 0:55:15The power, I just, if you were here to feel this, it's a deep rumbling
0:55:15 > 0:55:19sound of the river, I can feel it up through my feet.
0:55:19 > 0:55:24The power, I just can't imagine. That could crush a house in no time.
0:55:24 > 0:55:28The team takes to the air to witness the destruction that's unleashed.
0:55:28 > 0:55:32Huge ice blocks are pushed downstream on the wave of water
0:55:32 > 0:55:34released by the breaking waterfall.
0:55:38 > 0:55:40This could devastate the town.
0:55:44 > 0:55:48But, this year, the residents are lucky.
0:55:51 > 0:55:53There was no serious flooding,
0:55:53 > 0:55:58as the ice blocks didn't badly jam the river near to the town.
0:55:58 > 0:56:01As for the date of the break-up, 6th May,
0:56:01 > 0:56:05Red is right on the nose.
0:56:06 > 0:56:11I don't use any of these here gauges and mechanical assistance,
0:56:11 > 0:56:16I just go by what I see on the river as I walk it down.
0:56:16 > 0:56:21And I say I walk it down, back and forth every day on the river to see
0:56:21 > 0:56:26what's happening, and from that, I gauge when it's going to hit here
0:56:26 > 0:56:30and what the situation is going to be like when it does get here.
0:56:30 > 0:56:31You know, when it went this morning,
0:56:31 > 0:56:34I said to my students, "Guess what the date is?"
0:56:34 > 0:56:36Red told us it was the 6th May and we were, you know, I'm not
0:56:36 > 0:56:39surprised, because we've been here a couple of times and that's happened.
0:56:39 > 0:56:42Ten days, two weeks out and he just looks around and goes "5th May."
0:56:42 > 0:56:45How does he know that?
0:56:45 > 0:56:46It's incredible.
0:56:46 > 0:56:48It's because he just has lived on this river
0:56:48 > 0:56:52and lived this break-up for 50 years.
0:56:53 > 0:56:57Ice scientists are improving the accuracy of their predictions
0:56:57 > 0:56:59all the time, but in the meantime,
0:56:59 > 0:57:03the people of Hay River have a remarkable guardian.
0:57:03 > 0:57:07Red, you were completely right this year. Are you right every year?
0:57:07 > 0:57:09No, I'm...
0:57:09 > 0:57:15I miss the odd one. Yes, 1985, I missed it.
0:57:42 > 0:57:45Subtitles by Red Bee Media Ltd