- [Narrator] Stand on the equator
and you'll be moving at 1,670 kilometers per hour,
faster than the speed of sound.
That's how quickly Earth rotates
on its axis from west to east,
and that rotation is largely responsible
for the distribution of every desert,
forest, and swamp on the planet.
So, let's do a little experiment.
Let's say we reverse Earth's rotation, what then?
Well, you'll change a lot more
than just the sunsets.
This may seem like a ridiculous scenario at first,
but scientists have actually run simulations
for a backward-spinning Earth,
because it happens to be a great way to test
how well we can model our planet.
So, let's pretend we have a big, red button, and presto.
Now, as Earth slows down to reverse direction
everything would go flying to the east,
so the whole process will leave a huge mess.
But let's take a look at the equator
once Earth has gotten back up to speed.
These are the trade winds,
which normally blow westward due to Earth's rotation.
So on backwards Earth, they reverse,
and that's where things get interesting.
At first, changes would be relatively small.
Hurricanes, for example, would no longer travel
from east to west across the Atlantic,
and westbound flights would suddenly be much shorter
compared to eastbound. Not so bad, right?
Let's fast forward a few thousand years into the future.
Changes in overall rain patterns
would turn Africa's Sahara Desert from this,
to something more like this.
In fact one simulation estimated
that the deserts of the world would shrink
from 42 million square kilometers to 31 million,
providing new plant life which would absorb
more carbon dioxide from the atmosphere,
potentially offsetting the extreme warming effects
from climate change. Wow, maybe we really should
reverse Earth's rotation.
But hold on, if the trade winds reverse direction,
it means that other wind patterns change too,
including the prevailing westerlies
that normally blow east across the Northern Atlantic,
and bring warm winds from the ocean
to Northwest Europe, keeping winters mild.
But on backwards Earth, the westerlies reverse,
and instead, Europe is bombarded
with cold winds from Russia.
As a result, scientists estimate winter temperatures
would drop by up to 10 degrees Celsius.
In fact, most of the North Atlantic would grow colder.
Simulations show that the Gulf Stream,
which normally transports warm tropic waters
to the North would reverse and shrink.
In North America, the landscape would change drastically.
For example the iconic deserts of the American Southwest
would disappear, and become the deserts
of the Southeast instead.
And while you're packing up to move
to the beautiful new green pastures of Arizona,
take a look at the horizon,
and enjoy that peculiar sunset to the east.