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Water:
Hundreds of thousands of tons of it,
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lying frozen on the world's mountains.
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It covers not only the poles,
but caps great peaks on the equator.
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00:01:31,121 --> 00:01:36,354
Water molecules, distilled from the sea
by the sun's heat, condense in the sky.
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As they fall through the air,
they pack together into shapes
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that echo their six-fold symmetry
and form infinitely varied crystals of ice.
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They settle on the high mountains
and compact into snow and ice
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that is, chemically, almost pure water,
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much purer than the sea from which it came.
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On Mount Rainier in the United States,
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permanent snow begins at 7,000 feet.
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00:02:05,322 --> 00:02:11,022
You might think that this was one of
the most inhospitable places on earth for life.
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After all, no vegetation grows
on these snowfields,
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so there can be no animals that feed on it,
like marmots or mice or rabbits,
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and if there are no herbivores, there can't be
any predators like hawks or weasels.
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But in fact,
there is a surprising amount of life here.
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There is some life
actually within this snowfield itself,
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because this snow is not white, but red.
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The colour comes from microscopic plants:
Algae.
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The redness is produced
by light reflected from their cell walls,
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and is almost invisible when,
under the microscope, light shines through them.
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Internally, they're green with chlorophyll.
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00:03:02,746 --> 00:03:07,513
With its aid, they convert
carbon dioxide and water into sugars.
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These, and the minerals
dissolved in the melt water,
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are all the algae need to grow and reproduce.
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The winter snow will bury them feet deep,
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but in spring, when the surface melts,
they divide, develop tiny beating hairs
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and swim up towards the sunshine.
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As they age and the minerals are used up,
they change colour,
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forming huge smears of red
in snowfields all over the world.
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Eventually, the snow algae produce spores
as fine as dust
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and in that form they are blown
from one snowfield to another.
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But other, bigger animals,
also brought up by the wind,
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blow across the snows of Mount Rainier.
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Ladybirds. Thousands of them.
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Nobody knows why they come up
in such numbers and assemble like this.
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But in late summer they fly up from the valleys
up to these high peaks
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and here assemble in the rocks.
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When the winter snows come, the ladybirds
remain underneath the snow in the rocks,
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and then in the spring, as now,
the snow melts and the sun warms the ladybirds,
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and they become active
and fly off back to the valley to feed on aphids.
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The ladybirds are only temporary residents
of the Mount Rainier snowfields.
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Other insects manage, almost unbelievably,
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to live all their lives
in this seemingly inhospitable snow.
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The best time to find them is at night.
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A whole community lives here,
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feeding on pollen grains and the bodies
of dead insects blown up on the wind.
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Some, like this primitive relation
of the cockroach, a grylloblattid,
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have a body chemistry
so well adjusted to low temperatures
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that if you pick them up,
your hand's warmth will kill them.
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Permanent snow lies directly on bare rock,
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but lower down, where it comes and goes,
there can be a little vegetation to be grazed.
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Mountain sheep. These on Mount McKinley
are the kind known as Dall Sheep.
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Little ground squirrels live up here too.
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Unlike the sheep,
which retreat to lower altitudes in winter,
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the squirrels are permanent residents,
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insulated in their burrows from the frosts
by the cover of snow.
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There are sheep like these in mountains
all through North America, Asia and Europe.
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All carry big horns,
and the senior males, in autumn,
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00:06:42,799 --> 00:06:45,632
indulge in the most alarming courtship battles.
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00:07:28,645 --> 00:07:31,808
It's hard for plants to grow on steep, high slopes
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The warming by day and freezing by night
makes the gravelly soil slip downwards,
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so it's difficult for plants to keep a hold.
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With few plants, grazing animals are rare,
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though there may be more
than there appear to be at first sight.
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These, in the Himalayas, are blue sheep,
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so nimble and sure-footed they can reach
almost any vegetation on the steep slopes.
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But if these are rare, rarer still is the animal
that preys on them, the snow leopard.
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In summer it stays
at between 12,000 and 15,000 feet,
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hunting small rodents and birds
as well as mountain sheep.
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Snow leopards have been seen
as high as 18,000 feet in summer.
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But with winter's heavy snowfalls,
it retreats to the valleys.
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00:09:06,943 --> 00:09:12,848
Game is now so scarce that there's barely
enough to support more than one leopard,
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so this animal hunts alone.
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Its thick, dense fur is now paler.
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It has a thick, woolly undercoat
and cushions of hair under its paws
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which prevent it from sinking in the snow.
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The mountains of Africa, although so near
the equator, are permanently snow-capped.
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00:09:49,319 --> 00:09:53,119
Kilimanjaro, 19,000 feet high, is a volcano.
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00:09:53,523 --> 00:09:59,758
Mount Kenya, also volcanic,
is 2,000 feet lower but still has its own glaciers
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Each has its own animals and plants
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specially adapted to life at low temperatures.
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Here, at about 13,000 feet,
grow some most beautiful and dramatic plants:
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Giant groundsels and giant lobelias.
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At these altitudes, plants like these
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have to face two totally conflicting problems
every 24 hours.
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Every night the temperature falls so low
that they're in danger of freezing solid.
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00:10:27,957 --> 00:10:32,326
And every day the sun beats down so strongly
in this very thin air
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that it threatens to rob them of their moisture
by evaporation.
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00:10:37,534 --> 00:10:40,628
But look how this lobelia
deals with those problems.
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This little pond of water in the leaf rosette
freezes over every night,
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and this shield of ice
prevents the water beneath from freezing,
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so that it acts as a liquid jacket, preventing
the frost from reaching the heart of the plant.
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But as the day wears on and it gets warmer,
this water is in danger of evaporating
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00:11:04,794 --> 00:11:08,093
and the plant of losing
its night-time insulation.
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But it isn'tjust rainwater
that's accumulated in this rosette.
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It's been secreted by the plant itself
and it's slightly slimy.
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It contains pectin, a colloidal substance
which greatly reduces evaporation.
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But there's another kind of lobelia
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which deals with these two problems
in a quite different way.
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This one grows very tall
and has extremely long leaves,
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each fringed with tiny hairs
which act like an animal's fur,
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trapping air between them,
insulating the stem from chills.
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They also prevent the wind
from robbing the plants of moisture.
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00:11:52,308 --> 00:11:55,300
Each group of lobelias
is owned by a pair of sunbirds
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which collect the insects the plants attract.
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They keep themselves warm
with fluffed-up feathers.
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00:12:02,752 --> 00:12:05,243
And among the rocks are hyrax.
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The reason these little creatures are so tame
and I can get so close to them
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is just because they're living so high up.
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Up here, there are few creatures to prey on them.
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An occasional leopard may come up
and hunt them, but apart from that, nothing.
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And so they can come out
during the few brief hours of sunshine
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and bask on the rocks without any fear,
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just as they're doing now.
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Hyrax also live down on the hot plains below,
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but these, in response to the cold,
have developed particularly long fur.
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Despite their shape,
they often climb trees to crop leaves.
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But at these altitudes,
there's only grass and lobelias,
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and they share it with the little furry-eared rat.
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Mount Kenya, like its neighbours
Kilimanjaro and Ruwenzori,
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is an isolated patch of snow and ice
surrounded by the baking hot African plains.
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But the great mountains of South America,
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like Cotopaxi, 19,000 feet high, are very differen
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These volcanoes, some active, some dormant,
are not isolated peaks
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but part of a continuous range
that runs the length of the continent
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and is surrounded
by the high, cold plains of the altiplano,
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so their flanks support
a large and varied population of animals,
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all adapted to life
at high altitudes and low temperatures.
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Here lives a wild South American camel,
the vicuna.
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Its coat is fine, silky
and protected so well from the cold,
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that it has, paradoxically,
led to its near-extinction.
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Men have recognised that vicuna wool
has an unexcelled softness and warmth
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and hunted the animal for it
until it's close to extinction.
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The people of the Andes have domesticated
another wild camel, the guanaco,
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to produce heavy-fleeced versions
which produce excellent wool
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and serve as beasts of burden.
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Here, in Ecuador and Peru, near the equator,
wild camels live at around 14,000 feet.
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00:14:39,976 --> 00:14:44,970
But as you travel south down the Andes,
the snowline gets lower.
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00:14:45,348 --> 00:14:48,476
Half-way down,
2,000 miles south of Cotopaxi,
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the line of permanent snow
has dropped from 16,000 feet to 13,000 feet.
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A thousand miles farther south still,
the mountains are not so high
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but are almost completely covered with snow,
to within a few hundred feet of the sea.
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So, on the southernmost tip of South America,
in Patagonia and Tierra del Fuego,
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the guanaco doesn't live at great altitudes,
but almost at sea level.
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Yet it needs its warm coatjust as much,
for here, even in summer, it's very cold,
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and during the winter
the whole land is snowbound.
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The reason it gets colder nearer the pole
is not complicated.
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The sun's rays strike the earth
at the equator at right angles.
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00:15:51,114 --> 00:15:53,708
But as you travel round the earth,
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the rays become more and more glancing.
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00:15:57,754 --> 00:16:00,484
So a given amount of heat falling on the equator
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is distributed over a much greater area
in the polar regions
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and has to travel through more of the earth's
atmosphere, which weakens it still further.
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So down in Patagonia, the sun's rays are
very much less intense and carry much less heat,
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and the glaciers flow right down to the sea.
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00:16:33,556 --> 00:16:37,652
Farther south still,
across the near-frozen seas off Cape Horn,
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00:16:37,827 --> 00:16:40,625
you reach chains of small volcanic islands
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that run down towards
the Antarctic continent itself:
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00:16:44,801 --> 00:16:46,462
Remote, little-known archipelagos
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such as the South Sandwich
and, here, the South Orkneys.
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There are only two flowering plants that can
manage to survive in this bleak, icy country.
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One is a kind of thrift
and the other is a small, stunted grass.
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And apparently,
no land-living animals of any kind.
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00:17:10,760 --> 00:17:15,459
But when the snows melt in summer,
they reveal that the rocks and the boulders
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00:17:15,631 --> 00:17:20,227
are covered with over 100
different kinds of mosses and lichens,
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some of them rounded green cushions,
others like miniature trees.
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00:17:26,576 --> 00:17:31,172
The capacity of these simple plants
to endure cold is phenomenal.
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00:17:31,380 --> 00:17:35,817
Some species can even survive
being frozen solid for weeks on end.
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00:17:41,691 --> 00:17:47,186
Within this miniature tangled jungle
lives a whole menagerie of tiny animals.
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Primitive creatures
little bigger than pinheads
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00:17:51,667 --> 00:17:57,128
manage to survive by slowly chewing away
at the lichens and mosses during summer.
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00:17:57,506 --> 00:17:59,701
In winter they almost grind to a halt,
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00:17:59,876 --> 00:18:04,939
yet they survive unfrozen
because their blood contains a kind of antifreeze
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and remains liquid
even when the temperature falls well below zero.
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00:18:14,724 --> 00:18:19,252
The majority are vegetarians,
but there are also carnivorous mites among them
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which clamber around the grazing herds,
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picking off individuals as they fancy.
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00:18:26,502 --> 00:18:30,495
In this extreme cold,
the processes of life are greatly slowed down,
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00:18:30,673 --> 00:18:35,337
not only those of growth,
but those that lead to old age and death.
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So such tiny creatures,
which elsewhere might live for merely months,
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survive for two or three years
within the green mossy carpets.
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00:18:46,522 --> 00:18:50,458
The seas around these Antarctic islands
are strewn with ice.
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00:18:50,927 --> 00:18:54,055
The pack ice that litters the surface
is frozen sea water,
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00:18:54,230 --> 00:18:56,994
and in winter forms a solid cover to the sea.
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00:18:57,333 --> 00:18:59,062
The icebergs are different.
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00:18:59,235 --> 00:19:04,070
They're made of fresh water and have
broken away from glaciers flowing into the sea.
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00:19:06,275 --> 00:19:10,371
This is the source of those bergs:
The edge of a glacier.
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00:19:11,347 --> 00:19:14,908
Beyond it, the continent of Antarctica.
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00:19:16,218 --> 00:19:18,686
It's huge, bigger than the whole of Europe,
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and, for the most part,
it seems totally devoid of life.
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00:19:25,728 --> 00:19:28,925
But not all of Antarctica is snow-covered.
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00:19:29,165 --> 00:19:34,626
In parts of the interior there are valleys
where almost no snow ever falls.
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00:19:35,972 --> 00:19:39,499
This is as desolate a part of the earth as exists.
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00:19:39,909 --> 00:19:44,209
The cold is extreme,
it's drier even than the centre of the Sahara,
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00:19:44,380 --> 00:19:46,905
it's dark for half the year
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00:19:47,083 --> 00:19:51,315
and it's scoured by a never-ending howling wind.
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00:19:52,521 --> 00:19:56,048
And the wind is responsible
for these carvings in the solid granite.
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00:19:56,425 --> 00:19:59,917
Crystals of salt
form beneath tiny flakes on the surface,
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00:20:00,096 --> 00:20:04,965
and grow slowly, but so powerfully
that particles are broken loose.
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00:20:05,234 --> 00:20:10,467
The wind then sweeps them up and hurls them
at the rock face, eroding it still further.
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00:20:14,777 --> 00:20:19,714
Desolate though this waste of shattered rocks
may seem, there is life even here.
203
00:20:27,957 --> 00:20:31,984
Algae. Beneath the stone,
the wind doesn't dry it out,
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00:20:32,161 --> 00:20:34,425
and it's protected from the cold.
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00:20:34,930 --> 00:20:39,299
It gets the light it needs to grow
through the translucent rock.
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00:20:45,408 --> 00:20:48,502
There are also green patches
actually within the rock.
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00:20:48,844 --> 00:20:53,247
Algae have penetrated the microscopic spaces
between the rock's constituent particles
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00:20:53,416 --> 00:20:55,509
and there managed to grow.
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00:20:58,020 --> 00:21:00,181
Glaciers flow down these dry valleys,
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00:21:00,356 --> 00:21:04,019
fed by the ice cap
covering the continent's centre.
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00:21:04,360 --> 00:21:10,697
They're among the world's fastest moving,
advancing as much as 300 feet in a year.
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00:21:11,067 --> 00:21:16,835
As they surge downwards,
their surface is torn into thousands of crevasses.
213
00:21:32,354 --> 00:21:35,323
During the summer,
even though the winds are bitterly cold,
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00:21:35,491 --> 00:21:39,655
the sun is sufficiently strong
to melt a little of the glacier's surface.
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00:21:41,664 --> 00:21:45,691
Where it accumulates in pools,
blue-green algae grows vigorously,
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00:21:45,868 --> 00:21:50,737
its dark colour enabling it to absorb
a high proportion of the sun's feeble heat.
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00:21:54,944 --> 00:21:59,677
These pools and streams are the only places
in all of Antarctica's interior
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00:21:59,849 --> 00:22:02,215
where life flourishes in any abundance.
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00:22:03,853 --> 00:22:06,981
The earth, at the beginning of the history of life
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00:22:07,156 --> 00:22:10,216
before any higher plants
or any animals had appeared,
221
00:22:10,392 --> 00:22:13,122
must have looked something like this.
222
00:22:18,968 --> 00:22:23,462
Yet here, mysteriously,
lie the corpses of large animals.
223
00:22:24,473 --> 00:22:27,874
A crab-eater seal.
It looks comparatively fresh,
224
00:22:28,043 --> 00:22:33,345
but examination of its tissues
show that it is about 300 years old.
225
00:22:33,849 --> 00:22:36,443
This extreme climate has freeze-dried it.
226
00:22:36,785 --> 00:22:39,583
It must have lost its way,
perhaps because of sickness,
227
00:22:39,755 --> 00:22:44,021
and misguidedly crawled up here
from the coast, 25 miles away.
228
00:22:46,028 --> 00:22:51,728
Although the land of the Antarctic is almost steri
its waters are extremely fertile,
229
00:22:52,101 --> 00:22:57,869
so its margins, particularly the beaches
of its off-shore islands, are rich in life.
230
00:23:06,882 --> 00:23:10,682
These fur seals in South Georgia
flourish in great numbers
231
00:23:10,853 --> 00:23:12,548
because the surface waters of the seas
232
00:23:12,721 --> 00:23:17,624
are thick with shoals of floating shrimp:
Krill, which is their main food.
233
00:23:18,260 --> 00:23:22,424
Every year they come ashore to the beaches
to pup and mate.
234
00:23:25,301 --> 00:23:30,830
They're not true seals but eared seals,
for they have small external ears.
235
00:23:31,006 --> 00:23:35,807
Their hind flippers can be brought forward,
enabling them to move quite fast on land,
236
00:23:35,978 --> 00:23:38,139
something that true seals can't do.
237
00:23:38,514 --> 00:23:43,747
These fur seals retained and thickened
the fur of their land-living ancestors,
238
00:23:43,919 --> 00:23:51,485
so that now some of these big males
have manes which give them the name sea lion.
239
00:23:51,860 --> 00:23:55,159
This fur lies in two layers.
240
00:23:55,331 --> 00:24:00,064
There's an outer guard hair
and then a thick layer close to the skin,
241
00:24:00,236 --> 00:24:07,267
and that traps air in it and keeps
the animals warm when they go swimming.
242
00:24:07,443 --> 00:24:09,911
But the trouble with fur as an insulator
243
00:24:10,079 --> 00:24:16,348
is that if you dive too deep,
water pressure squeezes out the air.
244
00:24:16,619 --> 00:24:21,454
So fur seals, for the most part,
fish in the surface waters.
245
00:24:23,325 --> 00:24:28,388
True seals, like these elephant seal pups,
have a different kind of insulation.
246
00:24:28,631 --> 00:24:29,996
Their fur is sparse,
247
00:24:30,165 --> 00:24:34,761
but beneath the skin
is a thick layer of oily fat, blubber,
248
00:24:34,937 --> 00:24:37,201
which surrounds their entire body.
249
00:24:37,506 --> 00:24:40,532
Elephant seals dive to great depths to hunt squid,
250
00:24:40,709 --> 00:24:44,668
navigating in the dark with sonar and huge eyes,
251
00:24:44,947 --> 00:24:49,884
but they don't get chilled, for pressure
has no effect on blubber's insulating qualities.
252
00:24:50,452 --> 00:24:55,719
With every year, the blubber
which kept them so warm in the freezing seas
253
00:24:55,891 --> 00:24:57,188
loses its power.
254
00:24:57,593 --> 00:25:01,222
Because every year
the sea elephants have to moult,
255
00:25:01,397 --> 00:25:07,825
and in order to grow new skin they have to
bring a blood supply close to the surface.
256
00:25:08,070 --> 00:25:10,163
Blood vessels open up through the blubber
257
00:25:10,339 --> 00:25:14,799
and the skin is flushed with blood
just below the surface.
258
00:25:15,044 --> 00:25:18,775
If they stayed in the sea like that,
they'd chill very quickly.
259
00:25:19,048 --> 00:25:21,414
But they don't. Instead...
260
00:25:24,253 --> 00:25:29,316
...they haul themselves up onto the beaches
or into mud wallows like this one.
261
00:25:29,658 --> 00:25:31,785
And there, the big old bulls like that one
262
00:25:31,960 --> 00:25:36,556
must suppress the feelings of antagonism
they felt only a few months ago
263
00:25:36,732 --> 00:25:41,328
and lie close together with their fellows
in the interests of keeping warm.
264
00:25:48,143 --> 00:25:50,611
These are the biggest of all seals.
265
00:25:50,813 --> 00:25:56,183
The huge adult males develop a bladder
on top of their noses, like a kind of trunk.
266
00:26:01,123 --> 00:26:05,651
But they also justify their name
of sea elephant by their immense size.
267
00:26:06,028 --> 00:26:10,192
The bulls may grow to 20 feet long
and weigh three tons.
268
00:26:19,341 --> 00:26:23,903
If you wanted to pick a creature
to symbolise the frozen Antarctic wastes,
269
00:26:24,079 --> 00:26:27,173
you might well choose a creature like this.
270
00:26:27,349 --> 00:26:30,910
These are macaroni penguins
on the island of South Georgia,
271
00:26:31,086 --> 00:26:34,783
halfway between the tip of South America
and the Antarctic.
272
00:26:35,190 --> 00:26:41,254
But it seems the original penguins
evolved in relatively warm climates.
273
00:26:41,430 --> 00:26:45,457
Even today, there are species of penguins
that live on the equator,
274
00:26:45,634 --> 00:26:47,226
in the Galapagos islands.
275
00:26:47,569 --> 00:26:51,835
So this dense coat of feathers
with a layer of fat beneath it
276
00:26:52,007 --> 00:26:56,444
was probably developed
to keep them warm in the seas anywhere,
277
00:26:56,612 --> 00:27:00,378
but it serves them just as well
in the freezing Antarctic winds,
278
00:27:00,549 --> 00:27:03,950
standing on land or on a surging iceberg.
279
00:27:22,738 --> 00:27:25,400
And they are superb swimmers.
280
00:27:27,443 --> 00:27:29,877
Swift and agile through water,
281
00:27:30,045 --> 00:27:33,481
they come in to land
through breakers that would smash any boat
282
00:27:33,649 --> 00:27:36,482
with the resilience of rubber balls.
283
00:27:46,228 --> 00:27:49,720
These chinstrap penguins
are only a couple of feet high.
284
00:27:49,898 --> 00:27:52,458
King penguins are half as tall again.
285
00:27:52,734 --> 00:27:56,170
Large size can be an advantage in cold climates.
286
00:27:56,438 --> 00:28:01,273
The bigger a body, the smaller
the surface area of its skin relative to its volum
287
00:28:01,510 --> 00:28:05,446
So big penguins retain heat
better than small ones.
288
00:28:05,814 --> 00:28:09,181
But their great size
causes problems in breeding.
289
00:28:09,384 --> 00:28:12,512
They lay just one egg, which they keep warm
290
00:28:12,688 --> 00:28:17,148
by the rather inconvenient method
of holding it on top of their feet,
291
00:28:17,426 --> 00:28:22,420
covered by a fold of feathered skin,
for eight long weeks.
292
00:28:22,764 --> 00:28:28,031
When it does hatch,
the chick takes so long to mature
293
00:28:28,203 --> 00:28:31,195
that they have to feed it for a further ten months
294
00:28:32,274 --> 00:28:35,368
These king penguins
aren't the biggest of all penguins.
295
00:28:35,611 --> 00:28:39,547
They have a cousin, living farther south,
which grows even bigger.
296
00:28:39,781 --> 00:28:43,046
It, too, has fearsome problems in raising its chic
297
00:28:43,218 --> 00:28:46,654
and it solves them
in the most dramatic way imaginable.
298
00:28:47,222 --> 00:28:51,659
They lay their eggs not in spring,
but at the end of summer.
299
00:28:52,027 --> 00:28:55,394
Their breeding grounds
are on the permanent sea ice near the coast.
300
00:28:55,631 --> 00:29:02,537
The females return to the sea to feed,
leaving the males with the eggs.
301
00:29:02,804 --> 00:29:05,830
They shuffle back and forth,
each with an egg on his feet,
302
00:29:06,008 --> 00:29:08,203
held carefully above the ice.
303
00:29:15,584 --> 00:29:18,883
The gales intensify as the winter advances
304
00:29:19,054 --> 00:29:20,851
and the sun sinks lower.
305
00:29:22,658 --> 00:29:25,821
In the skies above, the aurora plays.
306
00:29:26,562 --> 00:29:30,259
The male emperors
stoically sit out the months of winter darkness.
307
00:29:30,666 --> 00:29:35,069
The sea ice can offer them no nest.
Not even a scree for a few pebbles.
308
00:29:35,237 --> 00:29:40,072
They have nothing to eat, and nothing to do
except protect the precious egg
309
00:29:40,242 --> 00:29:44,178
and prevent it from freezing
while the chick slowly forms inside it.
310
00:29:44,580 --> 00:29:49,574
As the gales intensify, the males huddle together
to give one another shelter.
311
00:29:50,586 --> 00:29:55,455
Then, 65 days after it was laid,
the chick begins to hatch.
312
00:30:13,475 --> 00:30:15,670
The newly-emerged chicks are hungry.
313
00:30:15,911 --> 00:30:21,315
All the male can provide is a little secretion
from his throat and long-empty stomach.
314
00:30:21,783 --> 00:30:23,080
He's close to starving himself,
315
00:30:23,251 --> 00:30:26,948
having been sustained
only by the layer of fat beneath his skin.
316
00:30:27,222 --> 00:30:29,588
He's lost a third of his weight.
317
00:30:32,361 --> 00:30:35,660
But soon after,
the female reappears with a full stomach
318
00:30:35,897 --> 00:30:40,334
and takes the chick onto her feet
for its first proper feed.
319
00:30:41,336 --> 00:30:46,035
Now the parents will take turns
to trek to the sea and back,
320
00:30:46,208 --> 00:30:48,073
bringing food for their youngsters.
321
00:30:48,744 --> 00:30:53,443
But now, at the end of winter,
the ice has extended far out to sea,
322
00:30:53,615 --> 00:30:57,984
and the penguins may have to walk 50 miles
to reach open water.
323
00:30:59,054 --> 00:31:02,217
The adults have a powerful urge
to cherish a chick.
324
00:31:02,591 --> 00:31:05,719
Those that have lost one
will try and adopt any that wanders by
325
00:31:05,894 --> 00:31:08,590
or incubate pieces of ice.
326
00:31:20,742 --> 00:31:22,937
Repeatedly, the parent in charge
327
00:31:23,111 --> 00:31:26,012
manages to find something
from the pit of its stomach
328
00:31:26,181 --> 00:31:28,342
to feed the ever-hungry chick.
329
00:31:33,355 --> 00:31:36,552
Until the chicks lose their down
and get their adult plumage,
330
00:31:36,725 --> 00:31:40,058
they can't swim and so can't feed for themselves.
331
00:31:40,595 --> 00:31:46,033
But being so big, they, like the king penguins,
take a long time to grow to full size,
332
00:31:46,201 --> 00:31:51,901
and so their parents must make the long march
to the sea to collect food for them.
333
00:31:53,742 --> 00:31:57,678
Though the winter is almost over,
there is still bad weather.
334
00:31:57,879 --> 00:31:59,346
Blizzards rage over the ice,
335
00:31:59,514 --> 00:32:05,749
and the young huddle together
in groups of their own amongst the parent birds.
336
00:32:10,525 --> 00:32:14,120
Many of the youngsters lack the strength
to withstand the cold.
337
00:32:14,429 --> 00:32:15,555
Many die.
338
00:32:16,965 --> 00:32:22,562
As the sun rises higher each day,
the adults suffer in a different fashion.
339
00:32:22,938 --> 00:32:26,806
On sunny days they get too hot
in their insulating blanket of feathers,
340
00:32:26,975 --> 00:32:30,035
and eat snow in order to cool themselves.
341
00:32:32,347 --> 00:32:35,407
The chicks still have their downy feathers
and can't swim.
342
00:32:35,584 --> 00:32:39,918
But ten months on from laying, the chicks fledge,
343
00:32:40,088 --> 00:32:44,582
and over the next few weeks,
they all walk down to the sea,
344
00:32:44,760 --> 00:32:49,288
which now, with the spring break-up
of the ice, is close at hand.
345
00:32:51,833 --> 00:32:55,633
Now, at last, the adults
can feed entirely for themselves.
346
00:32:56,104 --> 00:32:58,664
They've got two months
in which to restore their weight
347
00:32:58,840 --> 00:33:01,968
before they start
the whole process over again.
348
00:33:06,815 --> 00:33:09,340
These birds, at first sight so penguin-like,
349
00:33:09,518 --> 00:33:12,453
live not near the south pole, but the north.
350
00:33:12,888 --> 00:33:16,790
They're not penguins but guillemots,
members of the auk family.
351
00:33:17,392 --> 00:33:20,987
All auks, like penguins,
are excellent underwater swimmers.
352
00:33:21,196 --> 00:33:23,756
They use their wings like flippers,
353
00:33:24,065 --> 00:33:27,193
but they have not become
such specialised swimmers as the penguins,
354
00:33:27,369 --> 00:33:28,859
for they can still fly.
355
00:33:29,771 --> 00:33:33,002
These are the guillemots' smaller cousins,
the little auk.
356
00:33:51,359 --> 00:33:55,921
Auks and penguins, similar though they are,
are not closely related.
357
00:33:56,097 --> 00:33:59,931
They've come to resemble one another
by adopting a similar lifestyle
358
00:34:00,101 --> 00:34:02,126
at opposite ends of the earth.
359
00:34:05,440 --> 00:34:09,501
Unlike Antarctica,
that isolated continent surrounded by sea,
360
00:34:09,678 --> 00:34:14,638
the Arctic is connected by land
to more temperate regions.
361
00:34:14,950 --> 00:34:19,785
So the land animals of Europe and North
America have been able to colonise it
362
00:34:19,955 --> 00:34:23,083
and adapt to its particular demands.
363
00:34:25,560 --> 00:34:27,528
Foxes have moved up here.
364
00:34:27,863 --> 00:34:33,597
The Arctic fox's coat is lighter
than its southern cousin, and in winter turns whit
365
00:34:34,135 --> 00:34:39,095
On land, it feeds on small rodents,
and on ice floes, perhaps the odd bird.
366
00:34:39,474 --> 00:34:42,841
It's just as well the little auks
have kept their powers of flight.
367
00:34:58,793 --> 00:35:05,130
The ice floes are also the hunting ground
of one of the biggest of all carnivores.
368
00:35:12,741 --> 00:35:14,231
The polar bear.
369
00:35:15,176 --> 00:35:18,270
This one has killed a bearded seal.
370
00:35:30,525 --> 00:35:35,428
A young bear is eager to take a share of the kill,
but must be cautious.
371
00:35:35,697 --> 00:35:38,791
Adults sometimes kill youngsters in squabbles.
372
00:36:11,900 --> 00:36:17,736
The polar bear is clearly a close relative
of the bears that live in Europe and America.
373
00:36:18,206 --> 00:36:23,940
Its whiteness is an obvious adaptation
to the snow and ice, but so is its huge size.
374
00:36:24,412 --> 00:36:31,318
The principle of a big body retaining more heat
applies to bears as much as penguins,
375
00:36:31,553 --> 00:36:36,991
and polar bears are very much bigger than
their cousins in temperate lands farther south.
376
00:36:54,609 --> 00:37:00,309
Polar bears, if forced to, will eat all kinds of t
but their preferred food is flesh,
377
00:37:00,482 --> 00:37:02,279
particularly that of seals.
378
00:37:02,650 --> 00:37:06,518
They especially like the blubber
just below the seal's skin,
379
00:37:06,721 --> 00:37:10,179
and often leave the meat
for the scavenging gulls and foxes.
380
00:37:37,786 --> 00:37:42,519
Among the glaucous gulls is the much rarer
and pure-white ivory gull.
381
00:37:52,067 --> 00:37:57,733
The polar bear's white coat and great size
are not its only adaptations to Arctic life.
382
00:37:57,972 --> 00:38:01,499
It grips the ice with long, sharp claws
383
00:38:01,676 --> 00:38:07,273
and thick hair on the soles,
which also makes them excellent paddles,
384
00:38:07,582 --> 00:38:11,678
for the polar bear spends a lot of time swimming
during the summer.
385
00:38:54,295 --> 00:38:56,729
Ringed seals are much hunted by polar bears,
386
00:38:56,898 --> 00:39:01,301
and when on the ice,
must be constantly on the alert.
387
00:39:05,373 --> 00:39:09,002
They need ice holes
through which to leave the water,
388
00:39:09,177 --> 00:39:12,078
or at least stick up their heads to breathe.
389
00:39:17,852 --> 00:39:22,880
A polar bear will wait for many hours,
motionless, beside such a hole.
390
00:39:27,462 --> 00:39:31,990
They also stalk seals
that are rash enough to lie out on the ice.
391
00:39:47,715 --> 00:39:53,278
The polar bear has lost, but about once
in every five hunting days, it does kill,
392
00:39:53,488 --> 00:39:54,978
and that is enough.
393
00:40:03,031 --> 00:40:08,663
The most powerful effective hunter of all,
however, on the northern ice, is man.
394
00:40:12,440 --> 00:40:15,637
Eskimo, or Inuit,
as they prefer to call themselves,
395
00:40:15,810 --> 00:40:18,836
came up to the Arctic in very early times.
396
00:40:19,147 --> 00:40:22,776
Superb hunters,
they could live for many months in winter
397
00:40:22,951 --> 00:40:25,715
on nothing whatever but raw meat.
398
00:40:38,466 --> 00:40:43,904
They were so skilled at living on the ice
that with only a knife of bone
399
00:40:44,072 --> 00:40:48,099
they could make a waterproof house
from snow in an hour or so.
400
00:41:01,022 --> 00:41:03,547
A slab of sea ice made a window.
401
00:41:23,811 --> 00:41:27,770
Inside, the igloo was lit
with lamps fed by seal blubber.
402
00:41:28,082 --> 00:41:29,982
Heat from the flame and from their bodies
403
00:41:30,151 --> 00:41:35,555
could raise the temperature enough for them
to remove their heavy clothing and relax.
404
00:41:49,737 --> 00:41:53,332
It was a life of extraordinary rigour and privatio
405
00:41:53,775 --> 00:41:56,369
These pictures were taken 20 years ago.
406
00:41:56,644 --> 00:41:59,340
No Eskimo lives in this way today.
407
00:42:01,282 --> 00:42:03,477
The poles have not always been so cold.
408
00:42:03,718 --> 00:42:08,417
One explanation of why they've become so
is the warming effect of ocean currents.
409
00:42:08,656 --> 00:42:12,615
If they can circulate the waters of the polar seas
down towards the equator,
410
00:42:12,794 --> 00:42:14,887
they would keep them relatively warm.
411
00:42:15,129 --> 00:42:20,499
And maybe they did so 100 million years ago,
when the continents were arranged like this.
412
00:42:21,202 --> 00:42:25,400
But the continents have shifted,
the polar seas become more enclosed
413
00:42:25,573 --> 00:42:28,007
and any such currents interrupted.
414
00:42:30,611 --> 00:42:33,171
Meanwhile, during the same period,
415
00:42:33,348 --> 00:42:38,376
the Antarctic continent drifted south
until it came to rest over the south pole.
416
00:42:38,653 --> 00:42:43,454
Now ocean currents
could not keep that part of the world warm either,
417
00:42:43,624 --> 00:42:45,524
and so an ice cap formed.
418
00:42:46,227 --> 00:42:51,790
The whiteness reflected 90% of the heat
in the already feeble rays of the sun.
419
00:42:52,033 --> 00:42:56,527
So ice now covers all of Antarctica
and the seas of the north pole.
420
00:42:57,071 --> 00:43:00,234
Over the past million years
there have been other variations,
421
00:43:00,408 --> 00:43:03,206
due to the sun's varying strength,
422
00:43:03,378 --> 00:43:05,972
and the ice cover has waxed and waned.
423
00:43:06,314 --> 00:43:09,715
Now we're in one of the warmer phases,
424
00:43:09,884 --> 00:43:13,684
but even so, Antarctica is still buried
beneath ice a mile thick,
425
00:43:13,855 --> 00:43:20,283
and in the north, ice and snow
extend for 1,000 miles away from the pole.
426
00:43:42,083 --> 00:43:45,541
As you come down the mountain
or away from the pole,
427
00:43:45,720 --> 00:43:51,249
the land becomes warm enough to prevent it
being covered by ice and snow all year.
428
00:43:51,559 --> 00:43:55,757
Beyond, the country is bleak enough:
Boulders and gravel,
429
00:43:55,930 --> 00:44:00,958
rocks that have been ground to fragments
by the glaciers and pushed in front of them.
430
00:44:02,136 --> 00:44:07,335
This is the tundra,
a land full of strange shapes and patterns.
431
00:44:07,775 --> 00:44:11,541
Fine muds and sands
retain more moisture than coarse gravel,
432
00:44:11,712 --> 00:44:14,442
so when they freeze, they expand more
433
00:44:14,615 --> 00:44:19,609
and push the gravel outwards
to produce these geometric shapes.
434
00:44:20,021 --> 00:44:23,513
A foot down, the soil is still frozen, permafrost,
435
00:44:23,691 --> 00:44:26,489
so the summer melt water can't soak away
436
00:44:26,661 --> 00:44:31,997
and the land is covered with bogs and ponds
that lie within the polygonal ridges,
437
00:44:32,166 --> 00:44:36,125
so that the land looks almost
as though it's been cultivated by man.
438
00:44:39,841 --> 00:44:44,642
In places, the underground ice
pushes upwards into a mountain called a pingo.
439
00:44:45,546 --> 00:44:49,983
It looks like a small volcano,
but instead of hot lava in its heart,
440
00:44:50,151 --> 00:44:52,585
it has cold, blue ice.
441
00:45:04,031 --> 00:45:08,730
Although the ice relaxes its grip
for only a few weeks in summer,
442
00:45:08,903 --> 00:45:13,863
a surprising number of plants and animals
manage to find a permanent home here.
443
00:45:18,145 --> 00:45:20,613
Small flowering plants keep low,
444
00:45:20,781 --> 00:45:26,083
for close to the ground there is little wind
and the sun's rays can be quite warm.
445
00:45:33,661 --> 00:45:37,620
One kind of tree manages to live up here
in large numbers
446
00:45:37,798 --> 00:45:40,460
by adopting exactly the same policy.
447
00:45:41,702 --> 00:45:44,432
This is the Arctic willow and it lies flat.
448
00:45:44,605 --> 00:45:47,301
It grows extremely slowly
in these cold temperatures,
449
00:45:47,475 --> 00:45:52,811
and this one may be a century or so old.
450
00:45:53,948 --> 00:45:56,075
In shallow burrows in the topsoil
451
00:45:56,250 --> 00:46:01,347
live the harvesters of this meagre crop
of leaves and grass: Lemmings.
452
00:46:04,892 --> 00:46:08,760
In summer, when there's food about,
they breed with great speed.
453
00:46:08,996 --> 00:46:15,196
One female produces five or six babies
in a litter, four or five times in a single season
454
00:46:15,469 --> 00:46:18,836
So in a few months she may produce 30 young.
455
00:46:19,106 --> 00:46:23,475
The babies grow so quickly
that the first to be born in the spring
456
00:46:23,644 --> 00:46:26,772
can themselves produce young
before the winter returns.
457
00:46:33,521 --> 00:46:37,252
In summer, all the tundra plants
put out their leaves
458
00:46:37,425 --> 00:46:38,915
and there's lots to eat.
459
00:46:46,534 --> 00:46:49,697
The swarming hordes of lemmings attract hunters:
460
00:46:52,273 --> 00:46:53,706
Snowy owls.
461
00:47:06,721 --> 00:47:10,088
During the summer,
lemmings are the owl's main food.
462
00:47:29,276 --> 00:47:34,145
Abundant though the lemmings are,
the hunting has been poor for this owl.
463
00:47:34,348 --> 00:47:39,115
She may have laid as many as eight eggs,
but only one chick has survived.
464
00:47:54,702 --> 00:47:58,832
As the days lengthen,
herds of caribou migrate up from the south.
465
00:47:59,473 --> 00:48:05,070
Their calves were born early in the season
and the herd moves up to 15 miles a day
466
00:48:05,446 --> 00:48:10,179
They have to keep traveling in order
to find enough food to sustain them all.
467
00:48:39,180 --> 00:48:41,410
They follow the same route each year.
468
00:48:41,582 --> 00:48:44,415
In places, paths are worn 18 inches deep
469
00:48:44,585 --> 00:48:48,043
where the animals have passed,
century after century.
470
00:48:54,161 --> 00:48:56,026
Snow geese fly up, too.
471
00:48:56,330 --> 00:49:00,357
They've come from as far away as Mexico,
3,000 miles distant,
472
00:49:00,534 --> 00:49:04,903
to claim a share in summer's brief crop
and to breed.
473
00:49:14,014 --> 00:49:15,879
They exist in two forms:
474
00:49:16,050 --> 00:49:20,111
Ones with dark feathers on the body,
as well as pure-white ones.
475
00:49:20,488 --> 00:49:24,015
But they're all the same species,
and mixed couples are common.
476
00:49:28,095 --> 00:49:31,223
Soon the tundra is thick with their nests.
477
00:49:34,168 --> 00:49:38,434
Ptarmigan, now in their dark summer plumage,
feed on the willow scrub.
478
00:49:45,746 --> 00:49:49,375
The caribou take not only willow,
but grasses and lichen.
479
00:50:01,629 --> 00:50:05,861
The first snow geese to arrive
already have goslings,
480
00:50:06,033 --> 00:50:07,796
and are foraging as a family.
481
00:50:16,577 --> 00:50:18,636
Later arrivals are still on the nest,
482
00:50:18,813 --> 00:50:22,340
and can't leave until the last egg has hatched.
483
00:50:22,817 --> 00:50:25,843
While there, the first goslings to emerge
and their parents
484
00:50:26,020 --> 00:50:30,787
are plagued by hordes of voracious
blood-hungry mosquitoes.
485
00:50:45,573 --> 00:50:49,441
From the warming pools,
more and more mosquitoes hatch.
486
00:50:55,950 --> 00:51:00,410
They provide food for the red-necked phalarope,
and there are plenty to gather.
487
00:51:00,588 --> 00:51:05,821
A square yard of fresh water here
can produce 100,000 insects in a season.
488
00:51:06,894 --> 00:51:08,486
Now the blackfly larvae,
489
00:51:08,662 --> 00:51:12,223
which as eggs were attached to stones
in the shallow pools,
490
00:51:12,399 --> 00:51:14,663
are also beginning to emerge.
491
00:51:36,056 --> 00:51:42,655
Activity now is intense, for it is light
for almost the whole 24 hours of the day.
492
00:51:45,266 --> 00:51:49,100
But by late August,
the snow geese sense the imminence of winter
493
00:51:49,270 --> 00:51:51,465
and start to head southwards again.
494
00:52:01,348 --> 00:52:03,873
The caribou, too, end their grazing,
495
00:52:04,051 --> 00:52:07,043
and start to plod back across the tundra.
496
00:52:07,655 --> 00:52:09,520
As they go, they continue to feed,
497
00:52:09,690 --> 00:52:14,252
building up the reserves of fat they will need
to sustain themselves through the winter.
498
00:52:34,181 --> 00:52:39,050
As the weather gets colder and colder,
the need for shelter becomes more urgent
499
00:52:39,320 --> 00:52:42,221
and the herds may cover 25 miles in a day.
500
00:53:03,077 --> 00:53:08,481
And then, at last,
the returning travellers reach the first tall tree
501
00:53:08,849 --> 00:53:11,249
It's the start of the great coniferous forest
502
00:53:11,418 --> 00:53:14,945
that lies south of the tundra
right round the globe.
503
00:53:15,656 --> 00:53:18,853
The snow geese will fly on for thousands of miles,
504
00:53:19,026 --> 00:53:22,427
but the caribou have reached
their wintering grounds.
505
00:53:22,930 --> 00:53:24,898
The forest is a sanctuary
506
00:53:25,065 --> 00:53:28,364
which will protect them from the bitter winter col
507
00:53:28,736 --> 00:53:32,672
and it's here that we shall be coming
in the next programme.
508
00:53:32,722 --> 00:53:37,272
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