{1}{1}25.000
{1665}{1724}Winter in Antarctica.
{1726}{1825}The temperature has dropped|to minus 70 degrees centigrade,
{1827}{1889}and winds of 120 miles an hour
{1891}{1946}blow across the desolate icescape.
{2028}{2121}The centre of Antarctica|is in continuous darkness.
{2123}{2202}0nly its fringes see the bleak winter light.
{2204}{2283}The sea freezes over for hundreds of miles,
{2285}{2361}effectively doubling the size of the continent.
{2391}{2477}In winter, the Antarctic is a very lonely place.
{2479}{2535}As the temperature plummets
{2539}{2587}and the sea ice forms,
{2591}{2715}most of the wildlife that came down here|to take advantage of the brief summer season
{2717}{2780}is forced to retreat north again.
{2782}{2842}Practically nothing stays.
{2844}{2953}To survive in the deep south|at its most bitterly hostile
{2955}{3071}requires a very special animal|with very special adaptations.
{3073}{3157}Such a creature is the Weddell seal.
{3209}{3281}No other mammal lives throughout the year
{3283}{3332}as far south as this.
{3342}{3441}These seals|are just 800 miles from the pole,
{3443}{3512}and they stay here winter and summer.
{3516}{3560}Like all Antarctic seals,
{3562}{3629}they have a thick layer of blubber|to insulate them from the cold.
{3631}{3720}But the real key|to their success in surviving here
{3722}{3812}is their ability to keep open holes in the ice
{3814}{3898}so that they have|access to the sea the year round.
{3927}{4056}These holes are the only things|that break the white monotony
{4058}{4126}over hundreds of square miles of sea ice.
{4130}{4206}The seals, with no escape to the open ocean,
{4208}{4269}are forced to stay near the holes.
{4271}{4322}Each is a gateway
{4324}{4383}to and from the underwater world
{4385}{4465}in which the seals hunt and find shelter.
{4496}{4623}Underwater, the temperature|never drops below minus 1.8 degrees.
{4627}{4724}The seals retreat down here|during the worst winter storms
{4726}{4800}and so keep comparatively warm.
{5061}{5116}When you dive beneath the ice,
{5118}{5226}you enter, within seconds,|a totally different world.
{5228}{5282}Here, within a foot or so
{5286}{5366}of the gale-swept,|savagely cold wilderness above,
{5368}{5482}illuminated only by the dim blue|light filtering through the ice,
{5486}{5568}there is stability, peace,
{5570}{5637}and an eerie, unforgettable beauty.
{6616}{6682}Animals need special adaptations
{6684}{6755}to live in water that is below zero centigrade.
{6786}{6869}Most fish would explode|if they touched this glacier wall.
{6873}{6960}Crystals would immediately form in their cells.
{6962}{7089}These survive because their tissues|are loaded with anti-freeze.
{7226}{7278}Life beneath the ice,
{7280}{7333}compared with the white desert above,
{7335}{7392}is extraordinarily rich.
{7394}{7447}There are all kinds of invertebrates,
{7449}{7507}including giant jellyfish.
{8187}{8242}It's a very sheltered place,
{8244}{8300}for the permanent sea ice overhead
{8302}{8353}provides year-round protection
{8355}{8401}from waves and storms.
{8403}{8461}But food is scarce,
{8463}{8535}and many of these creatures|have become scavengers.
{8539}{8640}These starfish make a meal of seal faeces.
{8739}{8860}Weddell seals can dive|to 750 metres, possibly more,
{8862}{8897}in search of food.
{8899}{8963}At these depths, in permanent darkness,
{8965}{9064}they encounter a world|dominated by stalk sponges.
{9151}{9224}Growing extremely slowly in the cold,
{9226}{9330}the Antarctic invertebrates become giants.
{9520}{9569}Returning from depths
{9571}{9622}where a human would be crushed,
{9624}{9729}seals surface suffering none|of the effects of deep diving
{9731}{9794}that can cripple human swimmers.
{9986}{10046}0ctober in the far south.
{10048}{10181}Female Weddell seals haul out|on the sea ice to give birth.
{10386}{10511}Imagine the shock of leaving a womb|at plus 37 degrees centigrade
{10513}{10632}and being dropped on the ice|into a world of minus 20.
{11347}{11434}The pup has to suckle|and build a layer of blubber
{11436}{11472}as fast as possible.
{11474}{11558}It usually doubles its weight in ten days,
{11560}{11634}for Weddell milk is 60% fat,
{11636}{11704}one of the richest produced by any mammal.
{11747}{11791}Remarkably, after one week,
{11793}{11844}the pup is ready for a swim.
{11867}{11933}(M0THER L0WS T0 HER PUP)
{12206}{12296}The mother is anxious to get her pup|accustomed to the water
{12298}{12358}before the weather deteriorates.
{12697}{12760}At this time, more than any other,
{12762}{12826}breathing holes are jealously guarded.
{13551}{13624}Weddells have an especially wide gape
{13626}{13695}and long canine and incisor teeth,
{13697}{13758}which enable them to scrape away the ice
{13760}{13858}that is constantly forming|and threatens to close their breathing holes.
{13872}{13962}Their teeth aren't impervious|to this wear and tear
{13964}{14019}and are gradually worn down,
{14021}{14081}so that eventually the seal can't eat.
{14083}{14185}As a consequence,|Weddells die at about 20 years,
{14187}{14266}half the age of other Antarctic seals.
{14286}{14359}A male defends an underwater territory
{14361}{14450}and mates with all the females|that use his breathing holes.
{14452}{14514}It's an effective way of acquiring a harem,
{14516}{14583}because females must have|a refuge below the ice
{14585}{14646}from the extremes of the winter weather.
{14754}{14813}It might seem that there could not be
{14815}{14866}a more harsh existence than this,
{14868}{14940}but the environment here|is comparatively constant
{14942}{15009}and these seals are adapted to it -
{15011}{15067}protected by a coat of dense hair
{15069}{15160}and insulated by blubber|immediately beneath the skin.
{15187}{15306}Indeed, Weddells do far better|than most other seals.
{15310}{15356}If they are sufficiently fattened
{15358}{15410}in the six weeks before they wean,
{15412}{15483}95% of pups will survive.
{15643}{15729}These seals,|the most southerly in the world,
{15731}{15769}live in the shadow
{15771}{15882}of the largest active volcano|in Antarctica - Mount Erebus.
{16001}{16073}Erebus is a mountain of extremes.
{16075}{16212}In the crater, molten lava bubbles|away at 600 degrees centigrade,
{16214}{16254}and yet, on the summit,
{16256}{16351}temperatures rarely rise|above minus 45 degrees.
{16353}{16418}Even here, there is life.
{16420}{16483}The heat of the volcano produces steam
{16485}{16562}that rises to the rim|and melts the snow and ice,
{16564}{16604}leaving bare patches of rock -
{16606}{16686}home to heat-loving bacteria and algae.
{16688}{16744}Another extraordinary example
{16746}{16848}of how life can survive in the most|extreme conditions on Earth.
{17250}{17297}Behind Mount Erebus,
{17301}{17387}the trans-Antarctic mountains|stretch in a long broad band.
{17411}{17487}They are the most extensive range|on the continent,
{17489}{17536}running for some 2,000 miles
{17540}{17629}and separating|the great east and west ice caps.
{17742}{17839}Although many of the peaks|are over 4,000 metres high,
{17841}{17892}most of the range is blanketed
{17894}{17975}by vast glaciers which fill the valleys.
{18405}{18482}Hidden among the trans-Antarctic mountains
{18484}{18552}is one of the continent's greatest surprises -
{18554}{18594}the dry valleys.
{18596}{18726}Here is the largest area|of bare rock in Antarctica.
{18756}{18849}It's so arid|that falling snow soon evaporates
{18851}{18896}and never builds up.
{18930}{18998}The valley below me is the driest place on Earth.
{19000}{19067}It hasn't snowed or rained here for centuries.
{19069}{19169}In winter, the temperature falls|to minus 52 degrees centigrade
{19171}{19259}and the ground is permanently frozen|to a depth of half a mile.
{19263}{19330}Conditions are so extreme
{19332}{19461}that when scientists came to design|a vehicle to work on the surface of Mars,
{19463}{19532}they brought it to this valley|in order to test it.
{19534}{19631}A clue to the factor|that creates these conditions
{19633}{19710}lies in the extraordinary shape|of these boulders.
{19740}{19796}Although they are solid granite,
{19798}{19928}they have been carved by savage winds|that scream down off the ice cap.
{19957}{20046}These winds are so dry|that they instantly absorb
{20048}{20089}any moisture in the air,
{20091}{20184}and by doing so desiccate|and preserve organic tissues.
{20186}{20311}This mummified crabeater seal,|70 miles from the sea,
{20313}{20357}has probably been lying here
{20359}{20432}for 3,000 years or more.
{20465}{20503}You might suppose
{20505}{20617}that a place that can freeze-dry|seals' bodies for centuries
{20619}{20701}would be totally without life.
{20703}{20804}But even in these extreme conditions,
{20806}{20863}life does exist.
{20865}{20914}Pick the right sort of rock -
{20916}{20985}this is a light porous sandstone -
{20987}{21037}give it a hit...
{21101}{21184}...and there, a millimetre|beneath the surface,
{21188}{21248}within the actual fabric of the rock,
{21250}{21334}a band of green, the colour of life.
{21355}{21456}It is lichen that has managed|to penetrate and colonise
{21458}{21543}the microscopic spaces between|the grains of the porous rock.
{21545}{21613}It's the only place where it can survive
{21615}{21674}in these arid, desert-like conditions.
{21754}{21800}Above the dry valleys,
{21802}{21867}held back by the trans-Antarctic mountains,
{21869}{21935}stretches the ice cap itself.
{21937}{22002}This is the Antarctic plateau,
{22004}{22053}3,000 metres high.
{22265}{22410}There can be no more forbidding,|hostile, desolate places to be
{22412}{22492}than up here on the Antarctic plateau.
{22494}{22606}It's not just that human life|here seems insignificant -
{22609}{22660}it seems totally irrelevant.
{22703}{22827}A few spots of lichens|may grow on boulders
{22829}{22911}to within 200 miles of the South Pole,
{22913}{22954}and, in the summer,
{22956}{23059}maybe one or two|particularly adventurous snow petrels
{23061}{23140}will come up here to try and nest.
{23142}{23195}But come the winter,
{23197}{23268}absolutely nothing living
{23270}{23373}moves up here on the Antarctic plateau.
{23480}{23560}Even in summer, it is always winter here,
{23562}{23628}with temperatures averaging minus 30.
{23637}{23702}1.5 times the size of Australia,
{23704}{23808}this is the largest area|of lifeless wilderness in the world.
{23830}{23920}Snow petrels,|brief visitors here in summer,
{23922}{23989}are forced to spend the winter|hundreds of miles
{23991}{24077}to the warmer north,|at the edge of the frozen sea.
{24233}{24321}This is the frontier|between life in the ocean
{24323}{24411}and a desert of ice|where almost no animals dare go.
{24413}{24479}But one creature has to cross it -
{24481}{24516}the Emperor penguin.
{24824}{24929}In May, when the freezing waters|and cold winter temperatures
{24931}{25021}force other animals|to retreat to the warmer north,
{25023}{25103}Emperor penguins head south.
{25406}{25513}They make their way to a number|of traditional nesting sites.
{25515}{25625}In this one alone, there may be 25,000 birds.
{25714}{25774}Emperors are unique.
{25776}{25869}They are the only birds|to lay their eggs directly on ice.
{26167}{26268}Just hours after the female|has produced her single egg,
{26274}{26325}the male takes it over.
{26327}{26370}The transfer has to be quick
{26372}{26429}if the egg is not to freeze.
{26489}{26544}The male manoeuvres it
{26546}{26615}into a brood pouch lined with blood vessels
{26617}{26712}that keep the egg 80 degrees|warmer than the outside temperature.
{26714}{26777}There, under a flap of skin,
{26779}{26837}it's sealed away for the winter.
{26971}{27044}When the egg is safely|inside the male's pouch,
{27046}{27096}the females are free to go,
{27098}{27206}and they start the long trek back|across the sea ice, to the open ocean,
{27208}{27312}leaving their partners to face|the coldest conditions on Earth.
{27744}{27815}With temperatures of 70 below,
{27817}{27860}and in terrible storms,
{27862}{27933}the penguins huddle tightly together for warmth.
{27935}{28026}No other adult penguins|are so tolerant of one another,
{28028}{28112}but for Emperors this is the key to survival.
{28257}{28313}The co-operation is not random.
{28317}{28399}Those most exposed on the windward side
{28401}{28495}move around the huddle|to the more sheltered side.
{28497}{28597}So every bird gets a fair share|of the warmth in the middle
{28599}{28743}and takes its turn in enduring|the brunt of the Antarctic weather.
{29005}{29060}As midwinter approaches,
{29064}{29123}the sun disappears below the horizon
{29125}{29168}for the last time this season.
{29170}{29265}A month of total darkness lies ahead.
{29465}{29538}Above the huddle, the Southern Lights -
{29540}{29586}the Aurora Australis -
{29588}{29644}blaze across the winter sky.
{29685}{29765}These spectacular displays occur
{29767}{29835}as subatomic particles,|travelling through space,
{29839}{29904}enter the Earth's magnetic field.
{30436}{30525}As winter recedes,|the huddles begin to break up,
{30527}{30634}and heat that was trapped|within them for so long escapes.
{30636}{30752}These males,|who have not eaten for 115 days,
{30754}{30825}are close to death by starvation.
{30883}{30958}(SQUAWKING)
{31174}{31254}As the sun returns|to the southern hemisphere,
{31258}{31293}the female Emperors,
{31295}{31368}sleek and fat from months of feeding at sea,
{31370}{31425}begin the long march back to the rookery.
{31443}{31523}The sea ice is now at its fullest extent,
{31525}{31610}and they may have to walk 100 miles|to reach their colony.
{31861}{31919}By now the eggs have hatched
{31923}{32002}and the tiny chicks|are awaiting their first feed.
{32062}{32119}Each female times her return
{32121}{32181}to coincide with the hatching of her chick.
{32183}{32239}A male, having starved for so long,
{32243}{32297}can give the chick only one meal -
{32301}{32381}no more than a milky secretion|from his gut wall.
{32383}{32428}If his partner doesn't return
{32430}{32479}within ten days of the chick hatching,
{32481}{32598}he will have to abandon it and head|to the sea to find food for himself.
{32817}{32886}(TREMEND0US DIN)
{32970}{33032}It's a noisy time in the colony.
{33034}{33106}The courtship calling|that took place before winter
{33108}{33156}now brings its reward.
{33159}{33220}After a separation of over three months,
{33222}{33306}a bird can still recognise its partner's call.
{33380}{33446}(VARl0US CALLS)
{33750}{33787}When they find one another,
{33789}{33863}the pair perform their greeting ritual
{33865}{33956}to ensure there hasn't been|a case of mistaken identity.
{33958}{34054}Then the female gives their chick|its first proper meal -
{34056}{34105}half-digested fish.
{34347}{34419}She's very eager to take charge of the chick,
{34421}{34529}but the male, having cared for it|for so long, is reluctant to give it up.
{34531}{34635}She has literally to push him back|to get him to release it.
{34852}{34953}The transfer is a tricky manoeuvre|that must be done fast.
{34955}{35050}A chick left on the ice|for only two minutes will die.
{35669}{35751}The males, after their four-month ordeal,
{35753}{35839}near to starvation and desperate to feed,
{35843}{35930}have to walk 100 miles or so|back to the open sea.
{36008}{36078}Mothers and chicks spend the next few weeks
{36080}{36129}learning each other's call
{36131}{36175}and establishing a strong bond
{36177}{36252}that ensures they will recognise|one another in the months ahead
{36254}{36335}when she returns from feeding trips.
{36577}{36674}It's early spring|and the weather is still variable.
{36706}{36778}(H0WLING GALE)
{36905}{36969}Severe storms are a real threat
{36971}{37012}to the chick's survival.
{37014}{37096}An abandoned one seeks shelter|from passing adults.
{37098}{37150}0ne of them seems interested,
{37152}{37251}but the vital bond between|parent and chick isn't there
{37253}{37336}and eventually the adult walks off.
{37440}{37544}In fact, the adults do have|a strong instinct to protect chicks.
{37546}{37620}So much so that birds|that have not managed to breed
{37622}{37706}will try to take possession|of a stray or abandoned chick.
{37708}{37769}But this fostering never succeeds
{37771}{37876}because the adult has no partner|to help in rearing the waif.
{38519}{38602}These desperate unpartnered penguins
{38604}{38653}will sometimes fight over a chick
{38655}{38701}and crush it to death.
{39076}{39142}Mortality is high.
{39144}{39190}Many eggs don't hatch,
{39192}{39300}and of those that do,|25% die in the first few months.
{39307}{39394}Those that survive|have to grow fast and fledge
{39396}{39481}before the sea ice on which they live|breaks up beneath them.
{40029}{40116}These chicks take five months to rear.
{40118}{40210}0nly by incubating the eggs|through the harsh winter,
{40212}{40292}so that the chicks hatch|at the very beginning of the short summer,
{40294}{40377}is it possible for the Emperors|to breed every year.
{40422}{40517}It was to collect|an Emperor penguin's egg like this
{40521}{40601}that men made the first-ever land journey
{40603}{40686}in the bitter cold darkness|of the Antarctic winter.
{40688}{40785}Bill Wilson, the naturalist|on Captain Scott's expedition,
{40787}{40868}was fascinated|by the evolutionary origin of birds
{40870}{40964}and was convinced|that the embryo in an egg like this
{40966}{41036}would provide conclusive evidence of the link
{41038}{41130}between the feathers of birds|and the scales of reptiles.
{41132}{41229}So, on 12 June, 1911,|in the middle of winter,
{41234}{41289}he and two companions
{41291}{41402}left Captain Scott's hut here on Cape Evans
{41407}{41519}and set out for the Emperor penguin colony|on the other side of Mount Erebus,
{41521}{41563}65 miles away.
{41566}{41666}It was a trip|that became known with some justice
{41668}{41736}as the worst journey in the world.
{41758}{41807}The weather was abominable.
{41809}{41864}Their clothes and harnesses froze solid
{41866}{41924}and all three suffered terrible frostbite
{41926}{42014}as they hauled their sledges|over heavily-crevassed terrain.
{42016}{42119}0n the return journey, they lost|their tent in a violent storm.
{42121}{42243}By a miracle, they found it again|and made it back to the hut alive.
{42257}{42370}They brought back three eggs|and three Emperor penguin skins,
{42375}{42427}one of which is still here in Scott's hut,
{42429}{42479}preserved by the Antarctic cold.
{42494}{42605}Although the connection between|birds and reptiles is no longer in doubt,
{42608}{42700}the eggs did not provide the evidence|that Wilson thought they would.
{42702}{42810}Even so, the journey remains|one of the great epic stories
{42812}{42866}in the annals of polar exploration.
{42868}{42918}In the next programme,
{42920}{43001}we'll look at the history|of Antarctic exploration in more detail
{43003}{43118}and also see how people today|survive life in the freezer.