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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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00:01:27,087 --> 00:01:32,259
It covers not only the poles,
but caps great peaks on the equator.
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00:01:42,561 --> 00:01:47,983
Water molecules, distilled from the sea
by the sun's heat, condense in the sky.
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00:01:48,233 --> 00:01:51,361
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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00:02:11,048 --> 00:02:13,717
On Mount Rainier in the United States,
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permanent snow begins at 7,000 feet.
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00:02:18,222 --> 00:02:24,144
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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00:02:35,697 --> 00:02:42,579
and if there are no herbivores, there can't be
any predators like hawks or weasels.
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00:02:42,871 --> 00:02:48,210
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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00:03:06,228 --> 00:03:09,523
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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00:03:14,778 --> 00:03:17,865
Internally, they're green with chlorophyll.
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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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00:04:07,289 --> 00:04:11,251
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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00:04:29,102 --> 00:04:34,566
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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00:06:05,282 --> 00:06:08,619
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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00:07:07,511 --> 00:07:10,472
indulge in the most alarming courtship battles.
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00:07:55,350 --> 00:07:58,604
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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00:08:07,487 --> 00:08:09,907
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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00:08:19,333 --> 00:08:22,294
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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00:08:35,349 --> 00:08:41,688
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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00:09:22,312 --> 00:09:27,901
But with winter's heavy snowfalls,
it retreats to the valleys.
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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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00:09:53,969 --> 00:09:56,930
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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00:10:15,741 --> 00:10:21,830
The mountains of Africa, although so near
the equator, are permanently snow-capped.
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00:10:21,997 --> 00:10:25,959
Kilimanjaro, 19,000 feet high, is a volcano.
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00:10:26,376 --> 00:10:32,925
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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00:11:02,287 --> 00:11:06,875
And every day the sun beats down so strongly
in this very thin air
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00:11:07,042 --> 00:11:11,964
that it threatens to rob them of their moisture
by evaporation.
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00:11:12,256 --> 00:11:15,509
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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00:11:21,473 --> 00:11:26,311
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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00:11:33,485 --> 00:11:40,534
But as the day wears on and it gets warmer,
this water is in danger of evaporating
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00:11:40,701 --> 00:11:44,121
and the plant of losing
its night-time insulation.
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00:11:44,580 --> 00:11:49,042
But it isn't just 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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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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00:12:36,423 --> 00:12:39,343
They keep themselves warm
with fluffed-up feathers.
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00:12:41,178 --> 00:12:43,722
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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00:13:24,555 --> 00:13:27,724
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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00:14:04,887 --> 00:14:06,555
But the great mountains of South America,
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like Cotopaxi, 19,000 feet high, are very different.
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00:14:12,144 --> 00:14:17,024
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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00:14:36,627 --> 00:14:40,923
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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But as you travel south down the Andes,
the snowline gets lower.
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00:15:30,681 --> 00:15:33,934
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 coat just 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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00:16:39,249 --> 00:16:41,960
But as you travel round the earth,
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the rays become more and more glancing.
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00:16:46,173 --> 00:16:49,009
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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00:17:23,502 --> 00:17:27,798
Farther south still,
across the near-frozen seas off Cape Horn,
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00:17:27,965 --> 00:17:30,884
you reach chains of small volcanic islands
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that run down towards
the Antarctic continent itself:
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00:17:35,222 --> 00:17:36,974
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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00:18:02,291 --> 00:18:07,212
But when the snows melt in summer,
they reveal that the rocks and the boulders
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00:18:07,379 --> 00:18:12,176
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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00:18:18,807 --> 00:18:23,604
The capacity of these simple plants
to endure cold is phenomenal.
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00:18:23,812 --> 00:18:28,442
Some species can even survive
being frozen solid for weeks on end.
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00:18:34,573 --> 00:18:40,287
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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00:18:44,958 --> 00:18:50,631
manage to survive by slowly chewing away
at the lichens and mosses during summer.
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00:18:51,048 --> 00:18:53,342
In winter they almost grind to a halt,
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00:18:53,509 --> 00:18:58,764
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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00:19:08,982 --> 00:19:13,737
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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00:19:21,245 --> 00:19:25,457
In this extreme cold,
the processes of life are greatly slowed down,
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00:19:25,624 --> 00:19:30,462
not only those of growth,
but those that lead to old age and death.
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00:19:30,921 --> 00:19:35,008
So such tiny creatures,
which elsewhere might live for merely months,
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00:19:35,175 --> 00:19:39,096
survive for two or three years
within the green mossy carpets.
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00:19:42,140 --> 00:19:46,270
The seas around these Antarctic islands
are strewn with ice.
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00:19:46,728 --> 00:19:50,023
The pack ice that litters the surface
is frozen sea water,
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00:19:50,190 --> 00:19:53,068
and in winter forms a solid cover to the sea.
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00:19:53,443 --> 00:19:55,237
The icebergs are different.
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00:19:55,404 --> 00:20:00,450
They're made of fresh water and have
broken away from glaciers flowing into the sea.
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00:20:02,744 --> 00:20:06,999
This is the source of those bergs:
The edge of a glacier.
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00:20:08,041 --> 00:20:11,753
Beyond it, the continent of Antarctica.
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00:20:13,088 --> 00:20:15,716
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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00:20:23,015 --> 00:20:26,351
But not all of Antarctica is snow-covered.
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00:20:26,643 --> 00:20:32,316
In parts of the interior there are valleys
where almost no snow ever falls.
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00:20:33,734 --> 00:20:37,404
This is as desolate a part of the earth as exists.
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00:20:37,821 --> 00:20:42,284
The cold is extreme,
it's drier even than the centre of the Sahara,
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00:20:42,493 --> 00:20:45,120
it's dark for half the year
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00:20:45,287 --> 00:20:49,708
and it's scoured by a never-ending howling wind.
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00:20:51,001 --> 00:20:54,630
And the wind is responsible
for these carvings in the solid granite.
199
00:20:55,005 --> 00:20:58,675
Crystals of salt
form beneath tiny flakes on the surface,
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00:20:58,842 --> 00:21:03,931
and grow slowly, but so powerfully
that particles are broken loose.
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The wind then sweeps them up and hurls them
at the rock face, eroding it still further.
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00:21:14,149 --> 00:21:19,321
Desolate though this waste of shattered rocks
may seem, there is life even here.
203
00:21:27,913 --> 00:21:32,125
Algae. Beneath the stone,
the wind doesn't dry it out,
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00:21:32,292 --> 00:21:34,628
and it's protected from the cold.
205
00:21:35,212 --> 00:21:39,716
It gets the light it needs to grow
through the translucent rock.
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00:21:46,139 --> 00:21:49,351
There are also green patches
actually within the rock.
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00:21:49,685 --> 00:21:54,314
Algae have penetrated the microscopic spaces
between the rock's constituent particles
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00:21:54,481 --> 00:21:56,650
and there managed to grow.
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00:21:59,278 --> 00:22:01,530
Glaciers flow down these dry valleys,
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00:22:01,697 --> 00:22:05,534
fed by the ice cap
covering the continent's centre.
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00:22:05,868 --> 00:22:12,499
They're among the world's fastest moving,
advancing as much as 300 feet in a year.
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00:22:12,875 --> 00:22:18,881
As they surge downwards,
their surface is torn into thousands of crevasses.
213
00:22:35,063 --> 00:22:38,192
During the summer,
even though the winds are bitterly cold,
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00:22:38,358 --> 00:22:42,654
the sun is sufficiently strong
to melt a little of the glacier's surface.
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00:22:44,781 --> 00:22:48,952
Where it accumulates in pools,
blue-green algae grows vigorously,
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00:22:49,161 --> 00:22:54,249
its dark colour enabling it to absorb
a high proportion of the sun's feeble heat.
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00:22:58,629 --> 00:23:03,550
These pools and streams are the only places
in all of Antarctica's interior
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00:23:03,759 --> 00:23:06,178
where life flourishes in any abundance.
219
00:23:07,930 --> 00:23:11,183
The earth, at the beginning of the history of life
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00:23:11,350 --> 00:23:14,561
before any higher plants
or any animals had appeared,
221
00:23:14,728 --> 00:23:17,564
must have looked something like this.
222
00:23:23,654 --> 00:23:28,367
Yet here, mysteriously,
lie the corpses of large animals.
223
00:23:29,409 --> 00:23:32,955
A crab-eater seal.
It looks comparatively fresh,
224
00:23:33,163 --> 00:23:38,669
but examination of its tissues
show that it is about 300 years old.
225
00:23:39,211 --> 00:23:41,880
This extreme climate has freeze-dried it.
226
00:23:42,256 --> 00:23:45,175
It must have lost its way,
perhaps because of sickness,
227
00:23:45,342 --> 00:23:49,805
and misguidedly crawled up here
from the coast, 25 miles away.
228
00:23:51,890 --> 00:23:57,813
Although the land of the Antarctic is almost sterile,
its waters are extremely fertile,
229
00:23:58,188 --> 00:24:04,236
so its margins, particularly the beaches
of its off-shore islands, are rich in life.
230
00:24:13,662 --> 00:24:17,583
These fur seals in South Georgia
flourish in great numbers
231
00:24:17,791 --> 00:24:19,543
because the surface waters of the seas
232
00:24:19,751 --> 00:24:24,840
are thick with shoals of floating shrimp:
Krill, which is their main food.
233
00:24:25,507 --> 00:24:29,803
Every year they come ashore to the beaches
to pup and mate.
234
00:24:32,806 --> 00:24:38,604
They're not true seals but eared seals,
for they have small external ears.
235
00:24:38,770 --> 00:24:43,775
Their hind flippers can be brought forward,
enabling them to move quite fast on land,
236
00:24:43,942 --> 00:24:46,236
something that true seals can't do.
237
00:24:46,612 --> 00:24:52,075
These fur seals retained and thickened
the fur of their land-living ancestors,
238
00:24:52,242 --> 00:25:00,125
so that now some of these big males
have manes which give them the name sea lion.
239
00:25:00,542 --> 00:25:03,962
This fur lies in two layers.
240
00:25:04,129 --> 00:25:09,092
There's an outer guard hair
and then a thick layer close to the skin,
241
00:25:09,259 --> 00:25:16,600
and that traps air in it and keeps
the animals warm when they go swimming.
242
00:25:16,808 --> 00:25:19,353
But the trouble with fur as an insulator
243
00:25:19,520 --> 00:25:26,068
is that if you dive too deep,
water pressure squeezes out the air.
244
00:25:26,360 --> 00:25:31,406
So fur seals, for the most part,
fish in the surface waters.
245
00:25:33,367 --> 00:25:38,622
True seals, like these elephant seal pups,
have a different kind of insulation.
246
00:25:38,872 --> 00:25:40,290
Their fur is sparse,
247
00:25:40,499 --> 00:25:45,295
but beneath the skin
is a thick layer of oily fat, blubber,
248
00:25:45,462 --> 00:25:47,798
which surrounds their entire body.
249
00:25:48,131 --> 00:25:51,260
Elephant seals dive to great depths to hunt squid,
250
00:25:51,468 --> 00:25:55,597
navigating in the dark with sonar and huge eyes,
251
00:25:55,889 --> 00:26:01,019
but they don't get chilled, for pressure
has no effect on blubber's insulating qualities.
252
00:26:01,645 --> 00:26:07,109
With every year, the blubber
which kept them so warm in the freezing seas
253
00:26:07,276 --> 00:26:08,610
loses its power.
254
00:26:09,069 --> 00:26:12,865
Because every year
the sea elephants have to moult,
255
00:26:13,031 --> 00:26:19,705
and in order to grow new skin they have to
bring a blood supply close to the surface.
256
00:26:19,997 --> 00:26:22,207
Blood vessels open up through the blubber
257
00:26:22,374 --> 00:26:27,045
and the skin is flushed with blood
just below the surface.
258
00:26:27,296 --> 00:26:31,175
If they stayed in the sea like that,
they'd chill very quickly.
259
00:26:31,466 --> 00:26:33,886
But they don't. Instead...
260
00:26:36,847 --> 00:26:42,144
...they haul themselves up onto the beaches
or into mud wallows like this one.
261
00:26:42,519 --> 00:26:44,730
And there, the big old bulls like that one
262
00:26:44,897 --> 00:26:49,693
must suppress the feelings of antagonism
they felt only a few months ago
263
00:26:49,902 --> 00:26:54,698
and lie close together with their fellows
in the interests of keeping warm.
264
00:27:01,788 --> 00:27:04,333
These are the biggest of all seals.
265
00:27:04,541 --> 00:27:10,172
The huge adult males develop a bladder
on top of their noses, like a kind of trunk.
266
00:27:15,302 --> 00:27:20,057
But they also justify their name
of sea elephant by their immense size.
267
00:27:20,432 --> 00:27:24,770
The bulls may grow to 20 feet long
and weigh three tons.
268
00:27:34,321 --> 00:27:39,076
If you wanted to pick a creature
to symbolise the frozen Antarctic wastes,
269
00:27:39,243 --> 00:27:42,496
you might well choose a creature like this.
270
00:27:42,663 --> 00:27:46,416
These are macaroni penguins
on the island of South Georgia,
271
00:27:46,583 --> 00:27:50,379
halfway between the tip of South America
and the Antarctic.
272
00:27:50,838 --> 00:27:57,177
But it seems the original penguins
evolved in relatively warm climates.
273
00:27:57,344 --> 00:28:01,515
Even today, there are species of penguins
that live on the equator,
274
00:28:01,765 --> 00:28:03,392
in the Galapagos islands.
275
00:28:03,767 --> 00:28:08,188
So this dense coat of feathers
with a layer of fat beneath it
276
00:28:08,355 --> 00:28:13,026
was probably developed
to keep them warm in the seas anywhere,
277
00:28:13,193 --> 00:28:17,114
but it serves them just as well
in the freezing Antarctic winds,
278
00:28:17,281 --> 00:28:20,826
standing on land or on a surging iceberg.
279
00:28:40,429 --> 00:28:43,182
And they are superb swimmers.
280
00:28:45,309 --> 00:28:47,853
Swift and agile through water,
281
00:28:48,020 --> 00:28:51,648
they come in to land
through breakers that would smash any boat
282
00:28:51,815 --> 00:28:54,776
with the resilience of rubber balls.
283
00:29:04,912 --> 00:29:08,540
These chinstrap penguins
are only a couple of feet high.
284
00:29:08,707 --> 00:29:11,418
King penguins are half as tall again.
285
00:29:11,668 --> 00:29:15,297
Large size can be an advantage in cold climates.
286
00:29:15,547 --> 00:29:20,594
The bigger a body, the smaller
the surface area of its skin relative to its volume.
287
00:29:20,844 --> 00:29:24,932
So big penguins retain heat
better than small ones.
288
00:29:25,349 --> 00:29:28,852
But their great size
causes problems in breeding.
289
00:29:29,061 --> 00:29:32,356
They lay just one egg, which they keep warm
290
00:29:32,523 --> 00:29:37,152
by the rather inconvenient method
of holding it on top of their feet,
291
00:29:37,444 --> 00:29:42,658
covered by a fold of feathered skin,
for eight long weeks.
292
00:29:42,991 --> 00:29:48,497
When it does hatch,
the chick takes so long to mature
293
00:29:48,705 --> 00:29:51,792
that they have to feed it for a further ten months
294
00:29:52,918 --> 00:29:56,171
These king penguins
aren't the biggest of all penguins.
295
00:29:56,380 --> 00:30:00,509
They have a cousin, living farther south,
which grows even bigger.
296
00:30:00,717 --> 00:30:04,179
It, too, has fearsome problems in raising its chic
297
00:30:04,346 --> 00:30:07,891
and it solves them
in the most dramatic way imaginable.
298
00:30:08,517 --> 00:30:13,146
They lay their eggs not in spring,
but at the end of summer.
299
00:30:13,522 --> 00:30:17,025
Their breeding grounds
are on the permanent sea ice near the coast.
300
00:30:17,276 --> 00:30:24,491
The females return to the sea to feed,
leaving the males with the eggs.
301
00:30:24,741 --> 00:30:27,911
They shuffle back and forth,
each with an egg on his feet,
302
00:30:28,078 --> 00:30:30,414
held carefully above the ice.
303
00:30:38,088 --> 00:30:41,508
The gales intensify as the winter advances
304
00:30:41,717 --> 00:30:43,594
and the sun sinks lower.
305
00:30:45,429 --> 00:30:48,765
In the skies above, the aurora plays.
306
00:30:49,516 --> 00:30:53,395
The male emperors
stoically sit out the months of winter darkness.
307
00:30:53,812 --> 00:30:58,400
The sea ice can offer them no nest.
Not even a scree for a few pebbles.
308
00:30:58,567 --> 00:31:03,614
They have nothing to eat, and nothing to do
except protect the precious egg
309
00:31:03,780 --> 00:31:07,868
and prevent it from freezing
while the chick slowly forms inside it.
310
00:31:08,327 --> 00:31:13,540
As the gales intensify, the males huddle together
to give one another shelter.
311
00:31:14,583 --> 00:31:19,671
Then, 65 days after it was laid,
the chick begins to hatch.
312
00:31:38,440 --> 00:31:40,734
The newly-emerged chicks are hungry.
313
00:31:40,984 --> 00:31:46,615
All the male can provide is a little secretion
from his throat and long-empty stomach.
314
00:31:47,115 --> 00:31:48,450
He's close to starving himself,
315
00:31:48,617 --> 00:31:52,496
having been sustained
only by the layer of fat beneath his skin.
316
00:31:52,746 --> 00:31:55,249
He's lost a third of his weight.
317
00:31:58,168 --> 00:32:01,588
But soon after,
the female reappears with a full stomach
318
00:32:01,797 --> 00:32:06,468
and takes the chick onto her feet
for its first proper feed.
319
00:32:07,511 --> 00:32:12,391
Now the parents will take turns
to trek to the sea and back,
320
00:32:12,599 --> 00:32:14,518
bringing food for their youngsters.
321
00:32:15,185 --> 00:32:20,107
But now, at the end of winter,
the ice has extended far out to sea,
322
00:32:20,274 --> 00:32:24,862
and the penguins may have to walk 50 miles
to reach open water.
323
00:32:25,988 --> 00:32:29,241
The adults have a powerful urge
to cherish a chick.
324
00:32:29,658 --> 00:32:32,911
Those that have lost one
will try and adopt any that wanders by
325
00:32:33,120 --> 00:32:35,914
or incubate pieces of ice.
326
00:32:48,594 --> 00:32:50,888
Repeatedly, the parent in charge
327
00:32:51,054 --> 00:32:54,099
manages to find something
from the pit of its stomach
328
00:32:54,266 --> 00:32:56,518
to feed the ever-hungry chick.
329
00:33:01,732 --> 00:33:05,068
Until the chicks lose their down
and get their adult plumage,
330
00:33:05,277 --> 00:33:08,739
they can't swim and so can't feed for themselves.
331
00:33:09,323 --> 00:33:14,953
But being so big, they, like the king penguins,
take a long time to grow to full size,
332
00:33:15,120 --> 00:33:21,084
and so their parents must make the long march
to the sea to collect food for them.
333
00:33:23,003 --> 00:33:27,090
Though the winter is almost over,
there is still bad weather.
334
00:33:27,299 --> 00:33:28,842
Blizzards rage over the ice,
335
00:33:29,009 --> 00:33:35,516
and the young huddle together
in groups of their own amongst the parent birds.
336
00:33:40,479 --> 00:33:44,233
Many of the youngsters lack the strength
to withstand the cold.
337
00:33:44,566 --> 00:33:45,734
Many die.
338
00:33:47,236 --> 00:33:53,075
As the sun rises higher each day,
the adults suffer in a different fashion.
339
00:33:53,450 --> 00:33:57,454
On sunny days they get too hot
in their insulating blanket of feathers,
340
00:33:57,663 --> 00:34:00,833
and eat snow in order to cool themselves.
341
00:34:03,252 --> 00:34:06,463
The chicks still have their downy feathers
and can't swim.
342
00:34:06,630 --> 00:34:11,134
But ten months on from laying, the chicks fledge,
343
00:34:11,343 --> 00:34:16,014
and over the next few weeks,
they all walk down to the sea,
344
00:34:16,181 --> 00:34:20,936
which now, with the spring break-up
of the ice, is close at hand.
345
00:34:23,605 --> 00:34:27,526
Now, at last, the adults
can feed entirely for themselves.
346
00:34:28,026 --> 00:34:30,696
They've got two months
in which to restore their weight
347
00:34:30,904 --> 00:34:34,158
before they start
the whole process over again.
348
00:34:39,204 --> 00:34:41,790
These birds, at first sight so penguin-like,
349
00:34:42,040 --> 00:34:45,085
live not near the south pole, but the north.
350
00:34:45,502 --> 00:34:49,590
They're not penguins but guillemots,
members of the auk family.
351
00:34:50,215 --> 00:34:53,969
All auks, like penguins,
are excellent underwater swimmers.
352
00:34:54,219 --> 00:34:56,847
They use their wings like flippers,
353
00:34:57,181 --> 00:35:00,434
but they have not become
such specialised swimmers as the penguins,
354
00:35:00,642 --> 00:35:02,144
for they can still fly.
355
00:35:03,103 --> 00:35:06,523
These are the guillemots' smaller cousins,
the little auk.
356
00:35:25,626 --> 00:35:30,380
Auks and penguins, similar though they are,
are not closely related.
357
00:35:30,547 --> 00:35:34,551
They've come to resemble one another
by adopting a similar lifestyle
358
00:35:34,718 --> 00:35:36,887
at opposite ends of the earth.
359
00:35:40,307 --> 00:35:44,561
Unlike Antarctica,
that isolated continent surrounded by sea,
360
00:35:44,728 --> 00:35:49,900
the Arctic is connected by land
to more temperate regions.
361
00:35:50,234 --> 00:35:55,280
So the land animals of Europe and North
America have been able to colonise it
362
00:35:55,447 --> 00:35:58,700
and adapt to its particular demands.
363
00:36:01,328 --> 00:36:03,372
Foxes have moved up here.
364
00:36:03,705 --> 00:36:09,670
The Arctic fox's coat is lighter
than its southern cousin, and in winter turns whit
365
00:36:10,212 --> 00:36:15,384
On land, it feeds on small rodents,
and on ice floes, perhaps the odd bird.
366
00:36:15,801 --> 00:36:19,304
It's just as well the little auks
have kept their powers of flight.
367
00:36:35,988 --> 00:36:42,536
The ice floes are also the hunting ground
of one of the biggest of all carnivores.
368
00:36:50,502 --> 00:36:52,045
The polar bear.
369
00:36:53,005 --> 00:36:56,300
This one has killed a bearded seal.
370
00:37:09,021 --> 00:37:14,151
A young bear is eager to take a share of the kill,
but must be cautious.
371
00:37:14,401 --> 00:37:17,696
Adults sometimes kill youngsters in squabbles.
372
00:37:52,147 --> 00:37:58,237
The polar bear is clearly a close relative
of the bears that live in Europe and America.
373
00:37:58,779 --> 00:38:04,743
Its whiteness is an obvious adaptation
to the snow and ice, but so is its huge size.
374
00:38:05,202 --> 00:38:12,417
The principle of a big body retaining more heat
applies to bears as much as penguins,
375
00:38:12,709 --> 00:38:18,340
and polar bears are very much bigger than
their cousins in temperate lands farther south.
376
00:38:36,692 --> 00:38:42,656
Polar bears, if forced to, will eat all kinds of t
but their preferred food is flesh,
377
00:38:42,823 --> 00:38:44,700
particularly that of seals.
378
00:38:45,075 --> 00:38:49,121
They especially like the blubber
just below the seal's skin,
379
00:38:49,371 --> 00:38:52,958
and often leave the meat
for the scavenging gulls and foxes.
380
00:39:21,737 --> 00:39:26,658
Among the glaucous gulls is the much rarer
and pure-white ivory gull.
381
00:39:36,627 --> 00:39:42,549
The polar bear's white coat and great size
are not its only adaptations to Arctic life.
382
00:39:42,799 --> 00:39:46,470
It grips the ice with long, sharp claws
383
00:39:46,637 --> 00:39:52,518
and thick hair on the soles,
which also makes them excellent paddles,
384
00:39:52,809 --> 00:39:57,064
for the polar bear spends a lot of time swimming
during the summer.
385
00:40:41,525 --> 00:40:44,027
Ringed seals are much hunted by polar bears,
386
00:40:44,194 --> 00:40:48,824
and when on the ice,
must be constantly on the alert.
387
00:40:53,078 --> 00:40:56,874
They need ice holes
through which to leave the water,
388
00:40:57,040 --> 00:41:00,043
or at least stick up their heads to breathe.
389
00:41:06,091 --> 00:41:11,305
A polar bear will wait for many hours,
motionless, beside such a hole.
390
00:41:16,101 --> 00:41:20,814
They also stalk seals
that are rash enough to lie out on the ice.
391
00:41:37,206 --> 00:41:43,003
The polar bear has lost, but about once
in every five hunting days, it does kill,
392
00:41:43,212 --> 00:41:44,796
and that is enough.
393
00:41:53,180 --> 00:41:59,061
The most powerful effective hunter of all,
however, on the northern ice, is man.
394
00:42:03,023 --> 00:42:06,318
Eskimo, or Inuit,
as they prefer to call themselves,
395
00:42:06,485 --> 00:42:09,655
came up to the Arctic in very early times.
396
00:42:09,988 --> 00:42:13,742
Superb hunters,
they could live for many months in winter
397
00:42:13,951 --> 00:42:16,829
on nothing whatever but raw meat.
398
00:42:30,133 --> 00:42:35,806
They were so skilled at living on the ice
that with only a knife of bone
399
00:42:35,973 --> 00:42:40,143
they could make a waterproof house
from snow in an hour or so.
400
00:42:53,615 --> 00:42:56,285
A slab of sea ice made a window.
401
00:43:17,431 --> 00:43:21,560
Inside, the igloo was lit
with lamps fed by seal blubber.
402
00:43:21,852 --> 00:43:23,854
Heat from the flame and from their bodies
403
00:43:24,021 --> 00:43:29,651
could raise the temperature enough for them
to remove their heavy clothing and relax.
404
00:43:44,416 --> 00:43:48,212
It was a life of extraordinary rigour and privation.
405
00:43:48,629 --> 00:43:51,340
These pictures were taken 20 years ago.
406
00:43:51,632 --> 00:43:54,468
No Eskimo lives in this way today.
407
00:43:56,470 --> 00:43:58,764
The poles have not always been so cold.
408
00:43:59,056 --> 00:44:03,894
One explanation of why they've become so
is the warming effect of ocean currents.
409
00:44:04,186 --> 00:44:08,315
If they can circulate the waters of the polar seas
down towards the equator,
410
00:44:08,482 --> 00:44:10,651
they would keep them relatively warm.
411
00:44:10,901 --> 00:44:16,532
And maybe they did so 100 million years ago,
when the continents were arranged like this.
412
00:44:17,282 --> 00:44:21,620
But the continents have shifted,
the polar seas become more enclosed
413
00:44:21,829 --> 00:44:24,373
and any such currents interrupted.
414
00:44:27,042 --> 00:44:29,753
Meanwhile, during the same period,
415
00:44:29,920 --> 00:44:35,133
the Antarctic continent drifted south
until it came to rest over the south pole.
416
00:44:35,425 --> 00:44:40,430
Now ocean currents
could not keep that part of the world warm either,
417
00:44:40,639 --> 00:44:42,599
and so an ice cap formed.
418
00:44:43,350 --> 00:44:49,147
The whiteness reflected 90% of the heat
in the already feeble rays of the sun.
419
00:44:49,398 --> 00:44:54,111
So ice now covers all of Antarctica
and the seas of the north pole.
420
00:44:54,653 --> 00:44:57,990
Over the past million years
there have been other variations,
421
00:44:58,157 --> 00:45:01,076
due to the sun's varying strength,
422
00:45:01,243 --> 00:45:03,912
and the ice cover has waxed and waned.
423
00:45:04,288 --> 00:45:07,833
Now we're in one of the warmer phases,
424
00:45:08,000 --> 00:45:11,962
but even so, Antarctica is still buried
beneath ice a mile thick,
425
00:45:12,129 --> 00:45:18,844
and in the north, ice and snow
extend for 1,000 miles away from the pole.
426
00:45:41,575 --> 00:45:45,204
As you come down the mountain
or away from the pole,
427
00:45:45,370 --> 00:45:51,168
the land becomes warm enough to prevent it
being covered by ice and snow all year.
428
00:45:51,460 --> 00:45:55,839
Beyond, the country is bleak enough:
Boulders and gravel,
429
00:45:56,048 --> 00:46:01,261
rocks that have been ground to fragments
by the glaciers and pushed in front of them.
430
00:46:02,513 --> 00:46:07,893
This is the tundra,
a land full of strange shapes and patterns.
431
00:46:08,393 --> 00:46:12,314
Fine muds and sands
retain more moisture than coarse gravel,
432
00:46:12,481 --> 00:46:15,359
so when they freeze, they expand more
433
00:46:15,526 --> 00:46:20,739
and push the gravel outwards
to produce these geometric shapes.
434
00:46:21,156 --> 00:46:24,785
A foot down, the soil is still frozen, permafrost,
435
00:46:24,993 --> 00:46:27,913
so the summer melt water can't soak away
436
00:46:28,080 --> 00:46:33,669
and the land is covered with bogs and ponds
that lie within the polygonal ridges,
437
00:46:33,836 --> 00:46:37,965
so that the land looks almost
as though it's been cultivated by man.
438
00:46:41,844 --> 00:46:46,807
In places, the underground ice
pushes upwards into a mountain called a pingo.
439
00:46:47,766 --> 00:46:52,396
It looks like a small volcano,
but instead of hot lava in its heart,
440
00:46:52,563 --> 00:46:55,107
it has cold, blue ice.
441
00:47:07,035 --> 00:47:11,915
Although the ice relaxes its grip
for only a few weeks in summer,
442
00:47:12,124 --> 00:47:17,254
a surprising number of plants and animals
manage to find a permanent home here.
443
00:47:21,758 --> 00:47:24,303
Small flowering plants keep low,
444
00:47:24,469 --> 00:47:30,017
for close to the ground there is little wind
and the sun's rays can be quite warm.
445
00:47:37,941 --> 00:47:42,070
One kind of tree manages to live up here
in large numbers
446
00:47:42,237 --> 00:47:45,032
by adopting exactly the same policy.
447
00:47:46,325 --> 00:47:49,161
This is the Arctic willow and it lies flat.
448
00:47:49,369 --> 00:47:52,164
It grows extremely slowly
in these cold temperatures,
449
00:47:52,331 --> 00:47:57,878
and this one may be a century or so old.
450
00:47:59,087 --> 00:48:01,340
In shallow burrows in the topsoil
451
00:48:01,507 --> 00:48:06,803
live the harvesters of this meagre crop
of leaves and grass: Lemmings.
452
00:48:10,516 --> 00:48:14,561
In summer, when there's food about,
they breed with great speed.
453
00:48:14,770 --> 00:48:21,235
One female produces five or six babies
in a litter, four or five times in a single season
454
00:48:21,527 --> 00:48:25,030
So in a few months she may produce 30 young.
455
00:48:25,322 --> 00:48:29,868
The babies grow so quickly
that the first to be born in the spring
456
00:48:30,077 --> 00:48:33,330
can themselves produce young
before the winter returns.
457
00:48:40,337 --> 00:48:44,258
In summer, all the tundra plants
put out their leaves
458
00:48:44,424 --> 00:48:45,968
and there's lots to eat.
459
00:48:53,892 --> 00:48:57,187
The swarming hordes of lemmings attract hunters:
460
00:48:59,898 --> 00:49:01,400
Snowy owls.
461
00:49:14,955 --> 00:49:18,458
During the summer,
lemmings are the owl's main food.
462
00:49:38,478 --> 00:49:43,567
Abundant though the lemmings are,
the hunting has been poor for this owl.
463
00:49:43,775 --> 00:49:48,739
She may have laid as many as eight eggs,
but only one chick has survived.
464
00:50:05,005 --> 00:50:09,301
As the days lengthen,
herds of caribou migrate up from the south.
465
00:50:09,968 --> 00:50:15,807
Their calves were born early in the season
and the herd moves up to 15 miles a day
466
00:50:16,183 --> 00:50:21,146
They have to keep traveling in order
to find enough food to sustain them all.
467
00:50:51,385 --> 00:50:53,720
They follow the same route each year.
468
00:50:53,887 --> 00:50:56,849
In places, paths are worn 18 inches deep
469
00:50:57,015 --> 00:51:00,644
where the animals have passed,
century after century.
470
00:51:06,984 --> 00:51:08,944
Snow geese fly up, too.
471
00:51:09,236 --> 00:51:13,448
They've come from as far away as Mexico,
3,000 miles distant,
472
00:51:13,615 --> 00:51:18,203
to claim a share in summer's brief crop
and to breed.
473
00:51:27,671 --> 00:51:29,631
They exist in two forms:
474
00:51:29,798 --> 00:51:34,052
Ones with dark feathers on the body,
as well as pure-white ones.
475
00:51:34,469 --> 00:51:38,140
But they're all the same species,
and mixed couples are common.
476
00:51:42,394 --> 00:51:45,647
Soon the tundra is thick with their nests.
477
00:51:48,734 --> 00:51:53,155
Ptarmigan, now in their dark summer plumage,
feed on the willow scrub.
478
00:52:00,787 --> 00:52:04,541
The caribou take not only willow,
but grasses and lichen.
479
00:52:17,346 --> 00:52:21,725
The first snow geese to arrive
already have goslings,
480
00:52:21,975 --> 00:52:23,769
and are foraging as a family.
481
00:52:32,903 --> 00:52:35,072
Later arrivals are still on the nest,
482
00:52:35,280 --> 00:52:38,909
and can't leave until the last egg has hatched.
483
00:52:39,451 --> 00:52:42,579
While there, the first goslings to emerge
and their parents
484
00:52:42,788 --> 00:52:47,751
are plagued by hordes of voracious
blood-hungry mosquitoes.
485
00:53:03,183 --> 00:53:07,187
From the warming pools,
more and more mosquitoes hatch.
486
00:53:13,986 --> 00:53:18,615
They provide food for the red-necked phalarope,
and there are plenty to gather.
487
00:53:18,824 --> 00:53:24,288
A square yard of fresh water here
can produce 100,000 insects in a season.
488
00:53:25,414 --> 00:53:27,082
Now the blackfly larvae,
489
00:53:27,249 --> 00:53:30,919
which as eggs were attached to stones
in the shallow pools,
490
00:53:31,170 --> 00:53:33,505
are also beginning to emerge.
491
00:53:55,819 --> 00:54:02,659
Activity now is intense, for it is light
for almost the whole 24 hours of the day.
492
00:54:05,412 --> 00:54:09,416
But by late August,
the snow geese sense the imminence of winter
493
00:54:09,583 --> 00:54:11,835
and start to head southwards again.
494
00:54:22,179 --> 00:54:24,806
The caribou, too, end their grazing,
495
00:54:24,973 --> 00:54:28,101
and start to plod back across the tundra.
496
00:54:28,769 --> 00:54:30,687
As they go, they continue to feed,
497
00:54:30,854 --> 00:54:35,651
building up the reserves of fat they will need
to sustain themselves through the winter.
498
00:54:56,421 --> 00:55:01,468
As the weather gets colder and colder,
the need for shelter becomes more urgent
499
00:55:01,802 --> 00:55:04,763
and the herds may cover 25 miles in a day.
500
00:55:26,535 --> 00:55:32,166
And then, at last,
the returning travellers reach the first tall tree
501
00:55:32,583 --> 00:55:35,043
It's the start of the great coniferous forest
502
00:55:35,210 --> 00:55:38,922
that lies south of the tundra
right round the globe.
503
00:55:39,673 --> 00:55:43,010
The snow geese will fly on for thousands of miles,
504
00:55:43,177 --> 00:55:46,722
but the caribou have reached
their wintering grounds.
505
00:55:47,222 --> 00:55:49,308
The forest is a sanctuary
506
00:55:49,474 --> 00:55:52,936
which will protect them from the bitter winter cold.
49375
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