[Intro Music Plays]
I've just finished donning my overcoat, wool scarf, and three other layers I'll be wearing trekking around outside.
I'm on the highest, driest, windiest, and coldest continent on earth.
That's right, it's Bryan with you for the last time as we make our way through Antarctica
today.
And by the looks of it, you might want to put on something a little warmer for this
one.
I hope you can find your pdf and have it handy while you can still feel your fingers.
We're gonna need it as we journey through the icy terrain.
With that in mind, our objectives for today are to understand the unique land and climate
of Antarctica and describe the role Antarctica plays in the global climate.
Antarctica was the last continent to be discovered and explored; first cited by Russian, British,
and American sailors all in the 1820s.
The Ross Ice Shelf was explored by the 1840s but harsh conditions on the continent prevented
thorough exploration until 1895.
Roauld Amundsen of Norway and Robert Scott from Britain both reached the South Pole between
1911 and 1912, but Scott and his team did not survive the return trip.
If you're interested in the exciting exploration of Antarctica, read more about the 1914-1917
Imperial Trans-Antarctic Expedition.
Ernest Shackleton and his crew aboard the Endurance lived through one of the greatest
survival stories in modern history.
By the 1920s, people were able to explore the continent by airplane, and now they use
drones and satellites.
It's like they took the sport out of it.
Scientists have discovered that Antarctica is the fifth-largest continent; smaller than
South America but larger than Europe and Australia.
It is located at the very southern tip of the world, surrounding the south pole.
And unlike the ice cap in the north, it sits atop a large amount of land; over 10 percent
of Earth's landmass in fact.
The ice cap climate is the driest on Earth receiving less than 2 inches of precipitation
per year, technically making it a desert.
Drier even than the Sahara in North Africa or the Taklamakan in East Asia.
It is also the highest continent with an average elevation of 1.3 miles; compared to the rest
of the world's 0.6 miles above sea level.
Because it's so high up and so cold, the ice never melts.
So that 2 inches of snow sits atop last year's 2 inches and the year before 2 inches and
so forth.
When the pressure builds up compressing the snow, it becomes a massive ice sheet.
These ice sheets have been growing for hundreds of thousands of years and now range from 5600
to 7200 feet thick.
Even the thinnest ones are more than a mile thick, for now.
What do you think happens to the global sea level each year as two inches of water across
a 5.4 million square mile surface is trapped outside of the oceanic water cycle?
That's right, the ice sheets get thicker and the sea level drops.
Not by 2 inches, the ocean has a much larger surface area; on the order of 139 million
square miles of ice.
The incredible weight of the ice sheets puts so much pressure on the land that it pushes
it below sea level by as much as 260 feet.
This actually makes the earth somewhat elliptical.
If, and when, the ice returns to the ocean, sea-level rise will occur.
Keep this sea-level rise thought in your mind.
The lowest temperature ever officially recorded anywhere on Earth is -128.6° Fahrenheit at
the Soviet Vostok Station in 1983.
Unofficial temperatures as low as negative 144° Fahrenheit have been recorded high up
in Antarctica's mountains.
But, the average yearly temperature is a balmy -76° Fahrenheit and that number has been
rising in recent decades.
The ice affects the Antarctic climate and weather patterns throughout the Southern Hemisphere.
It reflects the sun's rays back into space rather than absorbing heat; one of the reasons
it's so cold there.
Warmer, slightly wetter, conditions near the coasts and the Transantarctic Mountains allow
glaciers to flow over land.
They slowly creep from mountains and ice sheet edges to the coast.
The average glacier moves between 360 and 3600 feet in a year.
Most of the rest of the land is mountainous so the glaciers provide the best path for
reaching the interior of the continent.
Hang on, what dangers do you think are posed by traveling atop a moving glacier?
Because they are moving and often get crevasses, or large cracks which can form at any time,
they can be dangerous to traverse.
The faster, easier way has its risks.
Antarctica also has ice shelves where creeping ice extends out over the ocean and forms permanent
extensions.
Some shelves cover huge areas of the Ross and Weddell Seas.
Ice on shelves can be more than six thousand feet thick and thin out as they extend further
into the ocean away from the pole.
The thin parts become brittle, break off, and melt back into warmer waters.
In 2002, over a 35-day period, the Larsen B Ice Shelf covering more than 1,250 square
miles of surface ice collapsed and broke up into thousands of icebergs, or floating pieces
of ice, in the Weddell Sea.
Think back for a second, how do you think sea level was affected when the ice from the
Larsen B Ice Shelf fell into the sea?
You might think that this ice falling into the sea would cause sea level to rise.
But, since Larsen B was an ice shelf, and not an ice sheet, there was no effect on sea
level at all.
But, climate scientists often point to rising global temperatures as a threat to Antarctic
ice sheets, citing a potential risk for a catastrophic 11 feet of sea-level rise in
the coming century.
Pack ice is floating ice driven together into a continuous mass and encircles the continent.
It can extend more than a thousand miles from land during the winter; 10 times larger than
it typically is during the summer.
This area is a convergence zone where colder Antarctic waters meet warmer Atlantic, Pacific,
and Indian Ocean waters.
The temperature convergence affects air pressure systems and causes intense storms along Antarctica's
coasts.
Few plants and animals can survive in these extreme conditions.
But contrast in temperatures mixes different layers of water along the edge of pack ice.
Nutrient-rich waters rise to the surface allowing krill to thrive; this brings whales and fish
which feed on the krill.
The fish become food for seals, penguins, and other animals.
Although no one lives permanently in Antarctica it does have a seasonal population of between
one thousand and five thousand people, depending on the year and what science operations have
been funded.
Eleven babies have been born in Antarctica, intentionally!
In the 1970s and 80s, Argentina and Chile sent pregnant mothers there in the summer
to try and bolster territorial claims.
Don't worry, the babies were all safe and made it back to South America making Antarctica
the continent with the lowest infant mortality rate, 0%.
In the late 1880s.
many nations agreed that Antarctic land had to be permanently occupied and actively governed
for a national claim to be valid; and this has never come to pass.
In the 20th century Argentina, Australia, Chile, France, New Zealand, Norway, and the
United Kingdom all claimed pie-shaped wedges of land, meeting at the South Pole.
These nations did this for a number of reasons including national pride and the wealth of
scientific information to be discovered.
But, mainly to claim ownership of resources yet to be discovered.
Coal has been found, but at this point, it is too expensive to mine and transport to
be profitable.
Recent geological discoveries also suggest a presence of oil, gold, iron, and other minerals.
The United States and the Ussr, the only world superpowers throughout most of the 20th century,
did not make any land claims and still refuse to acknowledge any other land claims.
In 1961 12 countries, including the U.S., ratified an Antarctic Treaty with many more
signing on later.
It protects peaceful use of the land, sharing scientific research, and it bans military
activity, nuclear explosions, and disposal of radioactive waste.
Later amendments have been added to protect wildlife, this makes it the world's largest
land reserve.
Time for our final critical thinking question in the lesson guide.
How do you think the treaty paved the way for future cooperation in exploration?
If you said that space exploration still follows this model for the time being, you're pretty
smart.
No country owns the moon or mars.
Space is peacefully explored and scientists share equipment and data.
But, corporations might have some different ideas in store for the future.
Today there are 70 permanent research stations, representing 29 countries.
There is a huge amount of data gathering.
One team extracted a core sample suggesting that the ice was formed over 450,000 years
ago, as its layers give clues about environmental conditions over time.
There is also an ongoing search for microscopic life forms in lakes deep in the bedrock.
These crevices have been sealed for millennia beneath the ice.
It's a potential gold mine for data about past life on Earth.
Just when you thought you'd seen it all, we had a whole new continent hidden up our sleeve,
saved for last.
And believe it or not, this complex, diverse, flawed, beautiful, surprising, wondrous Earth
of ours, still has thousands of treasures just waiting for you to discover. [Birds chirping]
[Music playing]
Hey everybody, Bryan here, and I know you've heard that before.
On behalf of myself, Richard, Nick, John, and Zach, the geography content team here
at MiaPrep, I wanted to say that it's been a privilege and a pleasure to bring this course
to you.
It's our hope that you've gained a deeper understanding of, and a rich appreciation
for, our planet and its many wonders.
We also hope the skills we've practiced for taking a closer look at our world will help
you think more critically and make better, more informed, decisions moving forward.
And remember this, wherever you travel in the days ahead, whether in your neighborhood
or around the globe, be on the lookout for all the amazing things to discover about the
natural world and the people within it.
There's so much to cherish and protect.
And as always my friends, keep exploring!
[Music Plays]