It’s been over 200 million years
since South America broke off Africa
into its own continent.
But now it’s behaving very strangely.
It’s taking on water and going down.
Earth’s crust consists of
moving tectonic plates that rest
on the hot, molten rock
of the mantle below.
Classified as either continental or oceanic,
there are somewhere between
15 to 20 of these plates.
And they fit together
just like pieces of a jigsaw puzzle.
Only these puzzle pieces
happen to pull apart
and collide with each other
from time to time,
in a movement called tectonic shift.
The South America Plate,
which includes the continent and a large part of the Atlantic Ocean,
is the smallest of all the major tectonic plates.
And it moves at a rate of about 3 cm (1.2 in) every year.
That's about as fast your fingernails grow.
This slow pace may not seem like any big deal.
Except that this makes the South America Plate
collide with the Nazca Plate on the western side.
And this slow-motion collision
has been causing massive earthquakes.
Like the 9.5 magnitude quake that shook Chile in 1960.
And today, it's going to send
nearly half a billion people
fleeing from the now-sinking continent.
When a continental plate like South America
meets an oceanic plate like Nazca,
one of these plates begins to submerge under the other.
This is known as subduction.
And for these two plates,
it’s happening at a rate of 8 to 10 cm (3 to 4 in) every year.
Usually, if an oceanic plate collides with a continental plate,
it's the oceanic one that goes down.
But if the roles were reversed,
it would be mayhem.
As the South American plate began to sink,
the Nazca plate would be getting sucked over it.
You could see a new trench form in the ocean.
It would be as deep,
if not deeper than the Mariana Trench.
But this subduction wouldn’t go smoothly.
Actually, it would be quite the opposite.
The plates could get stuck.
And this would build up a lot of pressure
along the fault line between them.
When the stress became too great,
the plates would break free.
And all that stored up energy
would be released as seismic waves.
You’d need to prepare for some extremely destructive volcanic eruptions,
earthquakes and tsunamis.
This region already sits along the Andean volcanic belt,
known for its major volcanic activity.
It's caused by the Nazca Plate
already sinking underneath the South American one.
Flip the script and things could get even crazier.
Imagine all these volcanoes becoming active at once.
You and the other 120 million people
living in countries like Colombia, Chile and Peru
would be displaced by these disasters.
And there would be a lot more lost than just homes.
We’d lose UNESCO World Heritage Sites
like the ancient city of Machu Picchu
or the incredibly beautiful city of Cartagena.
And maybe worst of all,
you’d see the Amazon rainforest disappear.
This place is home to 10%
of all species of plant and animal life on Earth.
It would mean mass extinction.
And it would have enormous and far-reaching impacts
on other ecosystems around the world.
With the Amazon gone,
there would be fewer trees to produce the oxygen you breathe.
Of course, you’d see the global markets
and supply chains take a devastating hit too.
Argentina and Brazil produce over half of the world’s soy.
No longer able to rely on this source of animal feed,
countries around the world would suffer food shortages.
And not only that, but without South America
you’d face a serious shortage of black gold.
And no, I don’t mean oil.
Brazil and Colombia account for 25% of the world’s coffee exports.
You’d better get used to not having
your morning cup of joe.
In the end,
as the South American plates slips lower and lower,
you would see the entire population of the continent displaced.
That’s about 438 million people.
There’s no country or continent on Earth
that could accept them all at once.
But hold on.
Time for a reality check.
South America isn’t really slipping into the mantle of the Earth.
So this kind of population relocation number crunching
shouldn’t be too high on your worry list.
Besides, it would be nothing
compared to the nearly 1.2 billion people
expected to be displaced due to climate-related events
by the year 2050.
Maybe all those volcanoes erupting at once
could actually help us avoid that problem.
But that’s a story
for another WHAT IF.