EARTH: THE POWER OF THE PLANETBBC Documentary, 2007Iain Stewarthttp://www.imdb.com/title/tt1145500/http://en.wikipedia.org/wiki/Earth:_The_Power_of_the_Planet_______________________________________
EXCERPTS:PART.1. VOLCANOESThe center of our planet is as hot as the surface of the Sun.
Iceland is sitting on hot plume.
It's what's known as the North American Plate.
The Earth's surface is broken up into seven major chunks called plates.
They're so enormous that they can carry an entire continent
and extend far under the sea.
And it's just as well that the Earth's inner heat
continues to push mountains up.
It's hard to imagine, but if the plates should ever stop moving,
our planet would become a water world.
It may take an unfeasibly long time,
but eventually the land would be worn down and washed out to sea
and Earth would be covered in a vast ocean several kilometres deep.
So it's thanks to the collision of the plates continually pushing the land up
that we've still got terra firma to stand on.
Around 700 million years ago,
our planet started to cool.
630 million years ago.
Temperatures swung from minus 50 C to plus 50.
in just a few hundred years,
as Earth endured the most extreme climate change in its history.
Subduction volcanoes are the most violent on Earth.
The irony is that subduction volcanoes are so highly explosive and destructive
because they're so gassy,
yet it's the release of the gas that's crucial to the Earth.
... but they're so much more than just a force of destruction.
They're the life force of our planet.
Quite simply, without volcanoes, i wouldn't be here
and neither would you.
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PART 2. ATMOSPHERE
The atmosphere that surrounds our planet
is made up of FOUR key layers,
each very different.
1. TROPOSPHERE12 KM thick
The troposphere is a rich soup of warm moist oxygen-rich air.
It's unstable, chaotic and unpredictable but life depends upon it.
2. STRATOSPHEREVirtually no weather.
Home to ozone layer.
On August 16th 1960,
military pilot Joe Kittinger
took a solo journey to the edge of space.
Not in a rocket but in a giant helium balloon.
He reached 31 kilometers.
Then Kittinger did something astonishing.
He jumped!
He fell to Earth, reaching the speed of almost 1000 km per hour.
and yet he could feel absolutely nothing. ...
Only when he re-entered the troposphere, the lower atmosphere,
did he experience the deafening
but reassuring roar of air rushing past him.
His jump remains the longest freefall in history.
Just 15 minutes after he jumped, Kittinger was back at the ground.
3. MESOSPHEREprotects from meteors.
noctilucent clouds - thin, wispy clouds that can only be seen at sunset, when they're illuminated from beneath by the low Sun.
4. THERMOSPHEREbeginning at 85 kilometers.
space shuttles orbits.
... that beyond the 100 kilometers
is declared to be the beginnings of space.
The Sun lethal solar wind is intercepted by Earth's magnetic field and diverted towards the poles
creating the aurora.
In fact the volumes of the atmosphere is just 5% of the Earth.
ATMOSPHERE IS LIQUID"And just like the ocean, the troposphere even has waves.
...
it forms regularly when bands of moist sea air approaches a long straight coasting where it's forced to rise by the land.
As the air cools, it condenses to form a cloud
which then rolls inland at 40 kilometers an hour,
visible evidence of the ocean of air above us.
And just like any fluid,
the atmosphere has a weight.
It presses down on each square centimeter of our bodies
with a force of one kilogram. ...
The only reason that we don't collapse in a heap
is because the air inside our bodies balances the pressure outside.
And if you're still in an doubt about the fluid nature of the atmosphere,
some people can even surf on it.. ...
These rocks are called THE WAVE.
You can see why.
The giant curvaceous shapes look as if they've been carved out by water.
Instead they've been sculpted by a different fluid motion,
the wind.
When the wind kicks up in the Sahara desert,
huge volumes of sand and dust,
rich in nutrients and minerals,
are lifted into the air to be blown out across the Atlantic.
Here, much of it falls into the sea
WHERE THE MINERALS FERTILIZE THE OCEAN,
In fact, a staggering 40 million tons of dust
is transported from the Sahara to the Amazon every year.
At the heart of everything is heat.
All weather, from the gentlest breeze to
the fiercest hurricane,
is the result of heat moving in the atmosphere.
... And that thunder that you hear
is because what's happening is as the cold and warm air masses mix,
it's a clash of extremes and this is a battleground.
The lightning is just the by-product of the extreme air movements
within the storm clouds.
As the moist air rises,
it cools and water particles freeze.
Some become small ice crystals,
others larger, slushy ice.
These two different types of ice collide
and become electrically charged.
An electric field builds up until it becomes so strong
it reaches for the Earth below.
They are called
SPRITES.This is a type of lightning
that doesn't strike down towards the ground
but instead reaches upwards,
sometimes as far as 75 km,
high into the mesosphere.
These lumps are one of the earliest forms of life on Earth.
They're called
STROMATOLITES.Stromatolites were the first life to photosynthesise
and release OXYGEN into our world.
The first thing oxygen did was give the planet a vital protective shield,
the ozone layer.
Methane is a greenhouse gas
that's 23 times stronger than carbon dioxide.
Global warming causes the permafrost to melt.
The more the permafrost melts,
the more fermentation happens in the bottoms of the lakes,
the more methane comes out which enhances global warming.
And it feeds back on itself.
So, melting, methane, melting, methane.
Right. It's almost like there's a time bomb waiting to go off.
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PART. 3. ICE
Glaciers are not formed from frozen water.
They're made from snow.
Every snowflake is formed from dozens of delicate ice crystals.
NO ONE HAS EVER FOUND TWO THAT ARE THE SAME.(Antarctica)... so only the peaks of high mountains called
NUNATAKS, can poke through.
(Antarctica)
MEGADUNES of ice, carved by centuries of relentless winds.
Each dune is six kilometres from the next.
The air is so cold that it hold almost no moisture
so, in fact, Antarctica is the biggest and driest desert on Earth.
Floating and Reflecting
Most substances are denser when solid than when liquid
which means they sink.
Ice is an exception.
Because it expands when it freezes,
it becomes less dense and so it floats.
It's also dazzlingly bright,
which makes it highly reflective,
and this combination has a dramatic effect on the Earth's climate.
These two qualities,
floating and reflecting,
make ice uniquely powerful on Earth.
Ice turns these polar regions into two giant reflectors,
and they don't just reflect light
but heat.
Land are sea are dark
so they absorb the Sun's warmth,
but ice reflects it
straight back out to space.
It's called the
ALBEDO EFFECT.Until as recently as 1997,
the glacier was relatively stable.
But in the last 10 years,
it's changed dramatically.
Florida would be one of the worst places to suffer.
(If Greenland ices (10% of the world ice) melts)
The northerncoast of Europe would be barely recognisable
and much of London would disappear beneath the waves.
And it isn't only Greenland's ice that's under the threat.
Around the world, it's the same story.
As more and more ice breaks off,
the whole process accelerates.
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PART. 4. OCEAN
Just like the any sea
the Mediterranean got most of its salt from rivers.
As the rivers flow over rocks and stones,
they gradually wear them down.
This releases salts trapped inside the rocks
which are carried down to the ocean as sediment.
Once in the ocean, the salts slowly become more concentrated
by millions of years of evaporation.
In fact, at just 90 cm tall,
this elephant was the size of a goat.
(elephant of Sicily)
The lack of space and food meant
that over thousand of years
the elephants evolved into a much smaller animal.
On 10th January, 1992,
an ocean freighter was caught in a big storm
out in the middle of the Pacific Ocean.
As winds and waves lashed the ship,
two of its giant containers crashed overboard
and their contents spilled out into the sea.
What burst out of those containers was bizarrely a shipment of these.
Plastic Bath Toys (Ducks).
More than 29,000 ducks were now adrift in the middle of the Pacific Ocean.
No one realised it at the time,
but this accident would eventually turn out to be
one of the biggest experiments
in the history of oceanography.
These ducks were about to embark on an epic voyage
of scientific discovery.
The moment they hit the water,
the plastic ducks joined a series of powerful ocean currents
which scattered them in different directions.
In just seven months, some were carried over 3500 kilometres,
washing ashore in places as far afield as Hawaii
and Alaska.
But for other ducks they voyage had only just begun.
They had embarked on a treacherous journey north,
up through the Bering Strait and into the Arctic Sea.
For the next few years,
the ducks were carried east in ice floes across the Arctic
and out into the North Atlantic.
Finally coming ashore on the east coast of America
and northern Scotland.
You know, these tough little plastic toys
had been carried for thousands of kilometres
across three different oceans,
simply by the power of those surface currents,
and are still turning up today.
The ducks' epic journeys
vividly revealed the complex system of currents
that connect all the oceans together.
Currents that are vital to life on the planet.
They carry nutrients and oxygen that nourishes life
and heat that drives the climate.
In fact, the oceans are giant reservoirs of heat
that's been captured from the Sun.
Ocean ConveyorWithout cold water sinking at the poles,
the ocean conveyor would collapse
If that were to happen,
then the sea would no longer be supplied with oxygen and nutrients.
It would become stagnant and lifeless.
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PART. 5. RARE EARTH 
Without the Moon, Earth's temperature would regularly switch
from baking hot to way below freezing.
Chicxulub meteorite
and that triggered the extinction of the dinosaurs.
The meteorite was 15 kilometers across,
The human race now moves more rock ans soil on the surface of the Earth
than all of nature's processes put together.
In fact, our influence is now so great
that scientists have declared that a new geological era has begun.
The Anthropocene,the human era.
In fact, since humans started pumping greenhouse gases
into the atmosphere,
the world's jungle have absorbed around
25% of all the carbon dioxide we've produced.
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