0:00:22 > 0:00:27Antarctica, the continent of the penguins.
0:00:27 > 0:00:29Busy little Adelis.
0:00:29 > 0:00:33Stately Emperors.
0:00:33 > 0:00:37And their close relatives, the King penguins.
0:00:41 > 0:00:45Summer is already giving way to the long winter night.
0:00:52 > 0:00:55The first storms of autumn are a warning.
0:00:55 > 0:00:58Penguins head for the warmer north.
0:01:06 > 0:01:08The Emperors alone stay put.
0:01:09 > 0:01:14In 90mph winds, and temperatures of 50 below, they lay their eggs.
0:01:23 > 0:01:28How do these birds cope with such extreme weather?
0:01:28 > 0:01:33And as the climate starts to change, what lies ahead for the penguins of the Antarctic?
0:01:41 > 0:01:46Ice, thousands and thousands of miles of ice.
0:01:49 > 0:01:52On both the sea...
0:01:52 > 0:01:55and the land.
0:01:55 > 0:01:58Antarctica's mainland is larger than Europe.
0:01:58 > 0:02:01But it lies under an ice cap two miles thick.
0:02:01 > 0:02:05In late autumn, there is no life here at all.
0:02:05 > 0:02:10Except at a few places where the frozen land meet the frozen sea.
0:02:10 > 0:02:14This dot on the north-west coast is one of them,
0:02:14 > 0:02:17an Emperor penguin colony.
0:02:17 > 0:02:24The world's most gruelling winter is on its way, so how have the Emperors prepared for it?
0:02:24 > 0:02:26By starting new families.
0:02:26 > 0:02:32They've courted, mated and their eggs are laid, one per pair.
0:02:33 > 0:02:37The mothers won't brood it though, the father will.
0:02:37 > 0:02:41And one of the most precarious parts of the whole process is the handover.
0:02:43 > 0:02:48Too many seconds on the ice, and the egg will freeze.
0:02:49 > 0:02:54So it's quickly on to the father's feet, and snuggled under a fold of skin.
0:03:00 > 0:03:03The mothers need to go to sea.
0:03:03 > 0:03:06Producing such a big egg has taken a lot out of them.
0:03:06 > 0:03:09They have to eat now. And they'll be back in the spring.
0:03:13 > 0:03:17After a short hike, they reach a break in the ice, take a gulp of air,
0:03:17 > 0:03:20and enter the element where they are most at home.
0:03:29 > 0:03:33As for the fathers, they get a lingering sunset.
0:03:33 > 0:03:37It is the last sunshine they'll see for more than two months.
0:03:37 > 0:03:40And the end of the last iota of warmth.
0:03:47 > 0:03:51Now they have darkness, savage winds, nothing to eat,
0:03:51 > 0:03:55and nothing to do but take their turn at the edge of the huddle
0:03:55 > 0:04:00and shuffle along on their heels as they keep their eggs off the ice.
0:04:07 > 0:04:10There is no sun, but they may get some comfort
0:04:10 > 0:04:15from the moon and the stars and the dancing southern lights.
0:04:15 > 0:04:17There is an inner comfort too,
0:04:17 > 0:04:20the instinctive confidence that the sun will return,
0:04:20 > 0:04:22and with it, their mates.
0:04:27 > 0:04:30Further north, other penguins have other concerns.
0:04:32 > 0:04:36If there are no islands around, they try to board icebergs.
0:04:48 > 0:04:51These are Chinstrap penguins.
0:04:51 > 0:04:54They, and the other small penguins,
0:04:54 > 0:04:58won't return to Antarctica until spring, their time to breed.
0:05:12 > 0:05:16Icy footholds are irrelevant, of course, to birds that fly.
0:05:16 > 0:05:19Storm petrels and fairy prions can simply rest
0:05:19 > 0:05:22on the unremitting southern winds.
0:05:26 > 0:05:29A wandering albatross rides the gale.
0:05:38 > 0:05:42There are a few battered islands, including South Georgia.
0:05:46 > 0:05:49The second largest penguins, the Kings, breed here.
0:05:52 > 0:05:55The chicks have already hatched.
0:05:55 > 0:05:59They huddle together, waiting for their parents to bring them food.
0:06:01 > 0:06:06They're kept warm by thick downy coats, so unlike their eventual adult feathers,
0:06:06 > 0:06:11that the first explorers here thought they were a new species, the woolly penguin.
0:06:17 > 0:06:21Sometimes, the King penguin parent will turn up with food.
0:06:21 > 0:06:26But these chicks, the albatross chicks, generally do without.
0:06:26 > 0:06:29This young albatross, high up on a cliff,
0:06:29 > 0:06:32has been alone and unfed for three months now,
0:06:32 > 0:06:34while its parents travel the southern seas.
0:06:44 > 0:06:49Many miles south, and many degrees colder,
0:06:49 > 0:06:53the Emperor fathers are still in darkness.
0:06:57 > 0:07:02Then, as the southern hemisphere starts to tilt back towards the sun,
0:07:02 > 0:07:06there is a hint of a new year in Antarctica.
0:07:07 > 0:07:11The sun seems also shy in its reappearance.
0:07:11 > 0:07:15It won't come clear at the horizon, but skims along it for a few hours,
0:07:15 > 0:07:19bringing very little light and no warmth.
0:07:20 > 0:07:23The temperature is still 30 below.
0:07:23 > 0:07:25It is still deep winter.
0:07:29 > 0:07:33As if the sun has sent a signal, it is now that the eggs hatch.
0:07:33 > 0:07:37There is now a bird, a hungry one.
0:07:37 > 0:07:39Only the mother can do anything about that.
0:07:42 > 0:07:44TWEETING
0:07:47 > 0:07:50If the mother doesn't bring food in a few days,
0:07:50 > 0:07:54the father, who is himself starving, will have to head for the sea
0:07:54 > 0:07:56and leave the chick to die.
0:08:03 > 0:08:07From somewhere out there, the mothers are coming.
0:08:51 > 0:08:55When they left for the sea, it was only a short walk away.
0:08:55 > 0:08:58Since then, the winter has extended the sea ice,
0:08:58 > 0:09:01and the trek back can be as far as 40 miles.
0:09:16 > 0:09:20Leopard seals and killer whales were waiting for them,
0:09:20 > 0:09:25but the injured keep going with the same determination as everyone else.
0:10:03 > 0:10:06Each mother calls for her mate.
0:10:28 > 0:10:33The pair celebrate their survival, their reunion and their chick.
0:10:48 > 0:10:52When the greeting ceremony is over, it's time to transfer the chick.
0:10:52 > 0:10:55But the father's been through hell with this baby,
0:10:55 > 0:10:59and doesn't always find it easy to let go.
0:11:14 > 0:11:16Eventually, he does.
0:11:22 > 0:11:23The chick eats at last.
0:11:23 > 0:11:30A meal of fish and squid caught a mile underwater, and carried 40 miles over ice.
0:11:30 > 0:11:34Now the fathers will finally go, and get to eat too.
0:11:37 > 0:11:41Not all the mothers have come back. A chick finds itself abandoned.
0:11:41 > 0:11:43And then adopted.
0:11:43 > 0:11:47Not all the surviving mothers have been able to find their mates.
0:11:50 > 0:11:54In fact, demand is greater than supply.
0:11:55 > 0:11:59And females will actually fight over orphans.
0:12:03 > 0:12:08In the end, there is no chance that one female can raise a foundling by herself
0:12:08 > 0:12:11and almost all abandoned chicks are abandoned again.
0:12:18 > 0:12:22One parent is needed to keep the chick warm, while the other goes for food.
0:12:22 > 0:12:28And for the next nine months, the successful fathers and mothers will do this in shifts,
0:12:28 > 0:12:32making and remaking the long slog over the sea ice.
0:12:36 > 0:12:39In the early spring, it is at its greatest extent.
0:12:39 > 0:12:43Sometimes, there are pit stops, thanks to Weddell seals
0:12:43 > 0:12:47which use their teeth to keep breathing holes open.
0:12:47 > 0:12:49Whales make holes too.
0:12:49 > 0:12:54The seals wear down their teeth, and end up toothless and starve.
0:12:57 > 0:13:03The temperature of the water under the ice is below zero, but is kept liquid by the salt content.
0:13:03 > 0:13:06No unprotected human could swim under here and survive.
0:13:06 > 0:13:12But for Antarctic animals, it's like a warm bath compared to conditions above the ice.
0:13:13 > 0:13:18Wwhile the top of the ice is bleak and barren, just a few feet down
0:13:18 > 0:13:21there is a busy living world.
0:13:25 > 0:13:31Shrimp-like krill, a staple food in the Antarctic, come here for the winter growth,
0:13:31 > 0:13:36relatively safe from penguins and seagulls, at least until the ice melts.
0:13:40 > 0:13:44This is a world that humans have only recently been able to explore.
0:13:44 > 0:13:48And nearly every day, something new is discovered down here.
0:13:48 > 0:13:53In 2005, for instance, scientists showed that the abundance of krill
0:13:53 > 0:13:57depended largely on the amount of winter sea ice.
0:14:01 > 0:14:05The extent on the ice is affected my climate change,
0:14:05 > 0:14:09something many scientists have come here specifically to study.
0:14:16 > 0:14:21One thing they have also established, is that the winter storms around Antarctica are getting more severe.
0:14:21 > 0:14:25The sea is becoming more treacherous for penguins, such as the Chinstrap.
0:14:37 > 0:14:43On South Georgia, these King penguin chicks are on the verge of starving.
0:14:43 > 0:14:49Very occasionally, parents turn up with food, but mostly the chicks have been living off their fat.
0:14:51 > 0:14:58As spring gets closer, the wandering albatrosses begin to make regular visits to their nest.
0:14:58 > 0:15:00They can range over 700 miles a day,
0:15:00 > 0:15:05gathering food for their chick, now the size of a swan.
0:15:09 > 0:15:15When spring does come, it comes to these outer islands first.
0:15:28 > 0:15:33After a season at sea, the King penguins return.
0:15:33 > 0:15:38Millions of animals will come ashore on these outlying Antarctic islands.
0:15:39 > 0:15:44King penguins, relatives of Emperors, prefer warmer climates.
0:15:44 > 0:15:49Does climate change mean that some day, the Kings will oust the Emperors?
0:15:57 > 0:16:01Among the arrivals are the three-ton bull elephant seals.
0:16:01 > 0:16:03They've come to fight.
0:16:07 > 0:16:10Winners will have as many as 50 mates.
0:16:10 > 0:16:12Losers won't have any at all.
0:16:23 > 0:16:25Waves of penguins arrive.
0:16:27 > 0:16:28Chinstraps.
0:16:30 > 0:16:32Macaronis.
0:16:35 > 0:16:38Gentu penguins.
0:16:42 > 0:16:46And they all head for high ground.
0:16:50 > 0:16:54The flamboyant Macaronis are the noisiest and the most numerous.
0:17:00 > 0:17:05They're here for the same reason as all the others - to produce chicks.
0:17:11 > 0:17:1680,000 King penguin chicks have been surviving on their fat.
0:17:16 > 0:17:19Their parents had been fishing in a warmer waters.
0:17:21 > 0:17:25Sometimes as far north as Australia and South Africa.
0:17:25 > 0:17:30Now they are back on South Georgia to carry on with the chicks' year-long upbringing.
0:17:34 > 0:17:38In fact, raising a King penguin chick takes longer than a year,
0:17:38 > 0:17:45which means that while some of the adults are still being parents, some non-breeders are moulting.
0:17:49 > 0:17:54And some are courting, performing the penguin pasa doble.
0:18:41 > 0:18:45It's easy to tell which ones are still being parents.
0:18:45 > 0:18:49Not only are they not moulting or dancing, they are doing a lot of fishing.
0:18:49 > 0:18:53Looking for lantern fish and squid miles to the north
0:18:53 > 0:18:57where the Pacific, Atlantic and the Southern Oceans merge.
0:18:59 > 0:19:02In the opposite direction, at the coast of Antarctica,
0:19:02 > 0:19:07the sea is slowly warming, and the sea ice is breaking up at its edges.
0:19:11 > 0:19:14There is a lot of ice left, though.
0:19:14 > 0:19:17Near the coast, the sea is as solid as ever,
0:19:17 > 0:19:22the sun is low and the midday temperature is 10 below.
0:19:22 > 0:19:27At the Emperor colony, spring has made life easier.
0:19:27 > 0:19:33The edge of the ice is nearer than it used to be, and getting food for the chicks is that much quicker.
0:19:35 > 0:19:39On the other hand, the chicks are growing fast and are a lot more demanding.
0:19:41 > 0:19:47The parents are in a constant relay race, to keep young stomachs filled.
0:19:48 > 0:19:53As the sea ice melts a little more each day, so each day the trip is shorter.
0:20:04 > 0:20:08The Antarctic is a strange upside-down at sort of place,
0:20:08 > 0:20:11with nothing much on the surface...
0:20:11 > 0:20:14and an abundance below it.
0:20:16 > 0:20:21Sometimes it's easy to forget that penguins are birds, but they are.
0:20:21 > 0:20:23And they are flying birds too.
0:20:23 > 0:20:26It's just that they live on top of their sky.
0:20:30 > 0:20:34They hunt fish and squid like swallows catching insects.
0:20:40 > 0:20:44No other birds fly faster under water.
0:20:44 > 0:20:48Emperor penguins can hold their breath for 20 minutes.
0:20:48 > 0:20:52They can dive beyond the reach of sunlight a mile down.
0:20:54 > 0:21:00They hunt in an ocean that, at this time of year, gets an explosion of new food.
0:21:00 > 0:21:05It happens here under the crumbling ice of the nursery for fish and krill.
0:21:05 > 0:21:11Their refuge is melting and they aren't safe any more from the penguins, seals and whales.
0:21:15 > 0:21:21The ice is also releasing a boost of minerals, in particular, iron.
0:21:21 > 0:21:28The sun, shining through the ice, sparks a growth of green algae which feed the krill.
0:21:28 > 0:21:31Their ice home disappears.
0:21:31 > 0:21:36Suddenly, krill have to take their important place in the wider world
0:21:36 > 0:21:41and, seeking safety in numbers, they gather in colossal swarms.
0:21:41 > 0:21:45The sheer mass of the Antarctic krill is greater than the mass
0:21:45 > 0:21:49of the total weight of any other animal on earth.
0:21:49 > 0:21:56Mammals and birds come from all over the world to transfer some of that weight to themselves.
0:21:56 > 0:21:59Including animals that are already among the largest.
0:21:59 > 0:22:04It's krill in fact that makes the biggest whales even possible.
0:22:12 > 0:22:15Chinstrap penguins eat almost nothing but krill.
0:22:15 > 0:22:17And there are about 15 million of them.
0:22:17 > 0:22:23One way of assessing the health of the krill is to keep an open eye on the Chinstraps.
0:22:23 > 0:22:27Chinstraps could also be indicators of climate change.
0:22:27 > 0:22:33Seas get warmer, and krill are concentrated further south, so Chinstraps go further south to breed.
0:22:35 > 0:22:40They've colonised this place, Zavodovski Island,
0:22:40 > 0:22:43just off the Antarctic coast.
0:22:43 > 0:22:49It's perfect for them, covered in bare rock, exactly what Chinstraps need for breeding.
0:22:49 > 0:22:54Of course, being close to Antarctica, it should be covered in snow and ice,
0:22:54 > 0:22:59but it isn't, because Zavodovski is a hot active volcano.
0:22:59 > 0:23:04So, the penguins have their own centrally-heated island
0:23:04 > 0:23:06with easy access to krill.
0:23:12 > 0:23:14Two million breed here.
0:23:14 > 0:23:18It's the largest Chinstrap colony in the world.
0:23:26 > 0:23:30The penguins that breed the furthest south,
0:23:30 > 0:23:34actually on the Antarctic continent, are the Adelis.
0:23:34 > 0:23:40And between them and their colony, are miles and miles of spring sea ice.
0:23:40 > 0:23:44Which means weeks of walking.
0:23:44 > 0:23:49The trip is longer than many the Emperors have to make, perhaps 60 miles.
0:23:49 > 0:23:54Nevertheless, in white bib and black tails, they set off.
0:24:46 > 0:24:50At least Adelis don't have to walk to their colony in winter.
0:24:50 > 0:24:53This is spring.
0:24:53 > 0:24:55Eventually they reach it.
0:24:55 > 0:25:00A patch of bare rock and pebbles on an Antarctic hillside.
0:25:00 > 0:25:03It's windswept too, but that's to the good.
0:25:03 > 0:25:08The sweeping wind, hurricane force sometimes, keeps the rocks free of snow.
0:25:10 > 0:25:12The summer this far south is short.
0:25:12 > 0:25:16Most families will be ready to leave in three months.
0:25:16 > 0:25:18Most of them.
0:25:18 > 0:25:22The breeding ground is also a graveyard for last year's chicks that didn't make it.
0:25:25 > 0:25:28Adelis live just inside the margins of possibility.
0:25:28 > 0:25:33Any unseasonably bad weather, and a whole generation can be lost.
0:25:38 > 0:25:40Breeding works this way.
0:25:40 > 0:25:45Males get there first, pick out nesting spots and court the females as they arive.
0:25:45 > 0:25:49A wave of the flippers, and a gutteral gossip is all they have time for.
0:25:51 > 0:25:55Most find their old partners and re-pebble their nests.
0:26:01 > 0:26:03The females lay two eggs.
0:26:03 > 0:26:08For at least the first fortnight the males incubate,
0:26:08 > 0:26:09then they take turns.
0:26:11 > 0:26:17The chicks hatch after a month and are fed for another two months in constant rush-hour relays.
0:26:41 > 0:26:46As the summer progresses, and days get longer, the Ice Age comes closer to the shore,
0:26:46 > 0:26:50which is convenient because the chicks are hungrier than ever.
0:26:56 > 0:27:00The 12ft Leopard seals are hungry too.
0:27:00 > 0:27:04The Adelis have to find ways of dodging them or sneaking by.
0:27:15 > 0:27:20By the time the days are 24 hours long, so are the fishing expeditions.
0:27:20 > 0:27:24The sun just goes around and around.
0:27:27 > 0:27:30There is little time for sleep.
0:27:37 > 0:27:42Melting icebergs roll through the water like drunken hillsides.
0:27:51 > 0:27:56Everything rushes to make the most of summer.
0:27:56 > 0:27:58Macaronis do rock-hopping.
0:28:02 > 0:28:05They charge back and forth for food.
0:28:19 > 0:28:23The Emperor penguins are on the 24-hour commute too.
0:28:41 > 0:28:44It's been six months since this chick's midwinter hatching
0:28:44 > 0:28:49and now it's demanding its bodyweight in food every week.
0:28:49 > 0:28:53For parents, there are simply no moments of peace.
0:29:13 > 0:29:18As soon as the chicks are fed, it's time to go hunting again for more.
0:29:22 > 0:29:26Sometimes Emperors fish as far north as South American and New Zealand waters,
0:29:26 > 0:29:31but usually they don't go beyond Antarctica's scattered islands.
0:29:31 > 0:29:35It's an area that is also the krill fishery of the Chinstraps.
0:29:41 > 0:29:45They nest high in this island's hills.
0:29:45 > 0:29:52And between the sea and the nests is a penguin superhighway, going up and coming down.
0:29:52 > 0:29:56The first seals which breed on the beach keep an eye on the traffic.
0:30:00 > 0:30:04From shore to nest is an hour's walk not counting setbacks.
0:30:06 > 0:30:09This one involves a torrent from a melting glacier.
0:30:30 > 0:30:34Never mind, Chinstrap penguins are seabirds after all,
0:30:34 > 0:30:37and very tough ones too.
0:30:37 > 0:30:41First they're deep sea divers, then they are mountaineers.
0:30:41 > 0:30:47This isn't a stroll up a hillside either, it is real climbing.
0:30:47 > 0:30:51And with the use of only two feet and a stiff supporting tail.
0:30:55 > 0:30:57It's volcanic ash up here,
0:30:57 > 0:31:02exposed because the strong winds have blown all the snow away.
0:31:02 > 0:31:05The parent who has just arrived will feed the chick,
0:31:05 > 0:31:10the other, who hasn't eaten for a couple of days will go down and fill up with krill.
0:31:10 > 0:31:15One reason the nests are in such a precarious place is to avoid predators.
0:31:19 > 0:31:22Something that is harder to do once they reach the water.
0:31:26 > 0:31:31A Leopard seal can eat penguins at the rate of six an hour.
0:31:31 > 0:31:35In a whole summer it can down thousands.
0:31:35 > 0:31:40It is possible, if very rare, for a penguin to be caught and get away.
0:31:44 > 0:31:49Despite the torments of skuas, it soldiers on.
0:31:54 > 0:31:58A Leopard seal, like any other predator, captures the animals
0:31:58 > 0:32:04that are easiest to catch, and this penguin was probably already in poor condition before it was attacked.
0:32:07 > 0:32:13In fact, the animals on the islands around the Antarctic peninsula are, to some extent, struggling.
0:32:13 > 0:32:20By 2005, most of the fish were gone, scooped up by the huge Antarctic fishing fleet.
0:32:20 > 0:32:24And shrinking sea ice has reduced krill by 80%
0:32:28 > 0:32:31This penguin has been particularly unlucky.
0:32:31 > 0:32:34But what's in the future for all the penguins?
0:32:42 > 0:32:46Climate change, as elsewhere in the world, is having mixed effects.
0:32:46 > 0:32:48The Antarctic peninsula,
0:32:48 > 0:32:53which stretches out towards South America, has warmed dramatically.
0:32:53 > 0:32:57The assumption was that the same was happening on the mainland,
0:32:57 > 0:33:01and that aerial and satellite surveys would confirm that.
0:33:05 > 0:33:07Not so.
0:33:07 > 0:33:11The surveys have shown that more snow than usual is falling on Antarctica,
0:33:11 > 0:33:14and that the ice cap is actually thickening.
0:33:23 > 0:33:30Around the peninsula, though, temperatures have risen five times faster than the world average.
0:33:30 > 0:33:33The ice is breaking up.
0:33:38 > 0:33:43Ice shelves the size of small countries have floated away.
0:33:43 > 0:33:48Antarctica is building up in the middle, and crumbling at the edges.
0:33:58 > 0:34:02It appears that the continent with virtually no pollution or people,
0:34:02 > 0:34:07is the one affected by changes in the atmosphere the most.
0:34:07 > 0:34:11Scientists still need to know precisely what the effects are.
0:34:11 > 0:34:17To help, they've looked more intently at what may already be the best studied sea bird in the world,
0:34:17 > 0:34:19the Adeli penguin.
0:34:19 > 0:34:22Adelis live in a world of ice.
0:34:22 > 0:34:27They feed under pack ice and rest on ice floes.
0:34:29 > 0:34:32Nowadays, though, the ice is unreliable.
0:34:39 > 0:34:42Adelis famously can put up with hardship.
0:34:42 > 0:34:44But these problems are new.
0:34:44 > 0:34:48Where there used to be ice, now there is open water.
0:34:48 > 0:34:53And the air is the warmest it has been since the last ice age.
0:34:54 > 0:34:58Chicks wait for their parents on what used to be frozen ground.
0:34:59 > 0:35:03But it is now as muddy as a pigsty.
0:35:12 > 0:35:17This colony used to be the most southerly outpost. It's not any more.
0:35:17 > 0:35:22Other Adelis are setting up colonies even further south.
0:35:22 > 0:35:29By following the Adelis' redistribution, scientists can trace the effects of the changing pack ice.
0:35:29 > 0:35:32The Adelis keep having new experiences.
0:35:32 > 0:35:34Invaders, for instance.
0:35:34 > 0:35:41Chinstrap penguins which avoid pack ice, do better in places where the Adelis are suddenly uncomfortable.
0:35:44 > 0:35:47Fur and Elephant seals are turning up too.
0:35:52 > 0:35:55The Adelis can't move. Not this year, anyway.
0:35:55 > 0:35:58Not before their chicks are grown.
0:35:58 > 0:36:01So they're stuck in the mud.
0:36:01 > 0:36:05As the long twilights turn into actual sunsets and short nights,
0:36:05 > 0:36:09the parents have to go further away for pack ice and food.
0:36:11 > 0:36:16When a parent comes back, its chicks recognise its call and are led away
0:36:16 > 0:36:22on a long steeplechase over the rocks, to a place where they can be fed in peace.
0:36:22 > 0:36:29Adelis usually have two chicks each and the most aggressive one is always fed first.
0:36:29 > 0:36:32As the pack ice shrinks, food is scarce now.
0:36:32 > 0:36:36Skuas are particularly alert to weak chicks that have not been fed.
0:36:43 > 0:36:47Sometimes, strong chicks are attacked as well.
0:36:47 > 0:36:53A frightened penguin often regurgitates its krill, and the skuas gratefully eat that too.
0:37:05 > 0:37:11The tension between skuas and penguins increases as summer nears its end.
0:37:11 > 0:37:17Both know it's important to fatten up before they leave for the winter.
0:37:19 > 0:37:22Until a few years ago, this was solid ice.
0:37:22 > 0:37:27Now, it's just broken ice floes and the water is warmer and salty.
0:37:41 > 0:37:46The Emperor penguin colony is nearer than it's ever been to the open sea.
0:37:50 > 0:37:53The chicks this year are very healthy.
0:37:53 > 0:37:58They are seven months old and already as big as adult Adelis.
0:37:58 > 0:38:03Being right next to the sea means their parents have quick access to fish and squid,
0:38:03 > 0:38:07and can feed them more frequently. That's the good news.
0:38:07 > 0:38:13The bad news is that the ice is still melting badly
0:38:13 > 0:38:16and the chicks don't have their swimming feathers yet.
0:38:16 > 0:38:19It's possible that the whole colony will disappear into the sea.
0:38:25 > 0:38:30There's trouble at Emperor colonies on several parts of the Antarctic coast.
0:38:30 > 0:38:34Many are getting smaller, some where they can, are moving further south.
0:38:37 > 0:38:42It's not known if a lot of chicks have been drowning, but that's possible too.
0:38:49 > 0:38:54On South Georgia, though, 1,000 miles to the north, the King penguins are flourishing.
0:38:56 > 0:39:02They breed on land and are used to warmer waters, so climate change has made little difference to them.
0:39:04 > 0:39:09100 years ago, they almost went extinct, hunted for skins and meat.
0:39:09 > 0:39:16But now, as other penguins decline, they could march south into new territories.
0:39:16 > 0:39:19Kings are definitely on the up.
0:40:03 > 0:40:05A new generation goes to sea.
0:40:07 > 0:40:11In changing times, there are also winners.
0:40:11 > 0:40:16The albatross chick is a year old and still growing, but is old enough
0:40:16 > 0:40:20to start learning to do what albatrosses are famous for.
0:40:26 > 0:40:29It spent its first winter on the nest.
0:40:29 > 0:40:32It will spend its second on the wing
0:40:32 > 0:40:36as a new generation is starting again.
0:40:36 > 0:40:40For albatrosses, the end of summer is the beginning of the year.
0:40:42 > 0:40:45The new chick will be fed throughout autumn,
0:40:45 > 0:40:49and will then be abandoned to spend winter alone.
0:40:52 > 0:40:54This time next year,
0:40:54 > 0:40:58it too will finally graduate to almost perpetual flight.
0:41:00 > 0:41:03Early in autumn, the sea ice is at its minimum.
0:41:03 > 0:41:09With each year warmer than the last, this is the minimum of the minimum.
0:41:12 > 0:41:16The Emperor penguins' colony is gone.
0:41:16 > 0:41:17Only some swimming birds are left.
0:41:17 > 0:41:23There is no way of knowing how many of the chicks born nine months ago in midwinter actually survived.
0:41:27 > 0:41:32There's more to this story though than just warmer seas and melting ice.
0:41:38 > 0:41:44Because the effects of global warming are so evident in the Antarctic, the handful of scientists
0:41:44 > 0:41:48who were working here 30 years ago have been joined by thousands of others.
0:41:48 > 0:41:53What they are finding is a lot less predictable than a gentle warming up.
0:41:53 > 0:42:00For a start, the increase in snow over the continental ice cap is making it colder.
0:42:00 > 0:42:06Air, at a temperature of 50 below, spins out of the centre in huge cyclones.
0:42:13 > 0:42:19Storm-force winds and waves then batter the fresh sea ice.
0:42:23 > 0:42:26As well as the animals that depend on it.
0:42:29 > 0:42:35The sea can be cold enough to freeze, but the autumn storms won't let it.
0:42:37 > 0:42:43In the Adeli colony on the edge of the continent, blizzards leave the parents
0:42:43 > 0:42:45hunkered down or stranded offshore.
0:42:48 > 0:42:53But penguins are hardy animals. The real killer is what can happen next.
0:42:53 > 0:43:01The winds can drop, the water calms, and the supercold continental air quickly freezes the sea.
0:43:05 > 0:43:10The adults might make it across, but few of the chicks would survive the trek.
0:43:10 > 0:43:15Unpredictable storms break up and refreeze the sea many times each autumn.
0:43:16 > 0:43:21Adeli chicks are growing waterproof feathers as fast as they can.
0:43:21 > 0:43:24As soon as they can, they follow their parents to the shore.
0:43:30 > 0:43:37The sea is full of heavy jagged chunks of ice, and the youngsters are naturally wary of taking the risk.
0:43:37 > 0:43:40But what's their choice?
0:43:40 > 0:43:42Stay here and starve?
0:43:45 > 0:43:51They can't get very far into the water though, and end up skittering across the broken ice.
0:44:09 > 0:44:13All the clumsy thrashing and hopping brings up another danger.
0:44:13 > 0:44:15A Leopard seal.
0:44:28 > 0:44:33It won't get every chick it tries for, but it knows a good hunting spot when it sees one.
0:44:37 > 0:44:40Finally, the fledglings take their first flight.
0:44:46 > 0:44:51Any youngsters that didn't take the plunge are quickly isolated and abandoned.
0:44:53 > 0:44:58As the south polar cyclones get even colder, they'll freeze.
0:45:07 > 0:45:12As autumn advances, so does the sea ice at an average of a few miles a day.
0:45:12 > 0:45:16And penguins are driven north, ahead of its edge.
0:45:16 > 0:45:21Chinstraps, Adelis and most of the other penguins will spend the winter at sea fishing.
0:45:26 > 0:45:28They cling to icebergs
0:45:28 > 0:45:31and generally wait for spring.
0:45:44 > 0:45:46Only one kind is heading south.
0:45:46 > 0:45:49The Emperors.
0:45:57 > 0:46:01Some Emperors are pioneering new colonies.
0:46:01 > 0:46:06They may be young, breeding for the first time, but they may have lost their home to the sea.
0:46:21 > 0:46:25They are heading further south so the ice won't melt under them.
0:46:27 > 0:46:29It will be colder here in winter too.
0:46:36 > 0:46:42At the same time, under their feet, the fresh sea ice is the roof of an Antarctic nursery.
0:46:43 > 0:46:48In almost total darkness, and safe from penguins, krill are growing again.
0:46:51 > 0:46:55The vital nurseries are changing with the climate.
0:46:55 > 0:47:00And a few feet above them, scientists are trying to work out what's changing, and where.
0:47:05 > 0:47:08Climatologists see an Antarctic in turmoil.
0:47:10 > 0:47:15Biologists say many animals will lose, but some will gain.
0:47:16 > 0:47:20Politicians are "talking about it".
0:47:20 > 0:47:25Some accept the science, others say it's unproven.
0:47:25 > 0:47:29In fact, nobody really knows where we are heading.
0:47:37 > 0:47:41As for the penguins, well, they're tough animals.
0:47:44 > 0:47:47They've coped with Antarctica up till now.
0:47:48 > 0:47:51Perhaps they can adapt to its future.
0:48:00 > 0:48:04Mid-winter, and each Emperor father has his egg.
0:48:09 > 0:48:13Each one is hungry, cold and in the dark.
0:48:16 > 0:48:23In the most extreme place on Earth, the penguins of the Antarctic soldier on.
0:48:41 > 0:48:44Subtitles by Red Bee Media Ltd, 2006
0:48:44 > 0:48:47E-mail subtitling@bbc.co.uk