Our planet has seen this before.
Its ice has already melted.
Water levels have risen.
Ocean currents have already stopped.
Now, everything is coming full-circle.
And we should be concerned.
If all those events were to happen again today,
you wouldn't recognize the Earth you're living in.
This is WHAT IF,
and here's what would happen
if the Gulf Stream shut down.
Ocean currents dictate the Earth's climate.
They push hot equatorial waters towards the poles,
and return cold polar waters to the equator.
In the northern hemisphere,
it's the Gulf Stream getting the job done.
Moving water at roughly 2 m/s (6.5 ft/s),
the Gulf Stream is one of the largest and fastest currents in the ocean.
It carries warm seawater all the way from the Gulf of Mexico
to the eastern coastlines of the U.S. and Newfoundland,
then across the Atlantic ocean, where it splits in two -
crossing to Northern Europe
and recirculating off West Africa.
The Gulf Stream is part of the global ocean conveyor belt.
So what does ice have to do with all this?
Currents circulating through the oceans
don't just appear out of nowhere.
They're created out of differences in water density.
Warm water has a lower density and rises to the surface.
Cold water has a higher density and therefore it sinks to the bottom.
But there's one more thing that determines the density of water -
the amount of salt in it.
And that's where the ice caps enter the game.
Polar ice is composed of fresh water.
As it melts, it adds more fresh water into the sea,
making the water in the North Atlantic less dense.
At some point, it won't be able to sink anymore.
The global ocean conveyor belt will stop circulating.
This would be the end of the Gulf Stream,
and the beginning of something else.
You heard it right.
We may be heating up the planet year by year,
but climate isn't that simple.
The Gulf Stream is a warm current.
It's what makes winters on the west coast of Europe so mild.
It also keeps winter temperatures warmer
and summer temperatures cooler on Florida's east coast.
What would happen if this warmth-bearing current was cut off?
Well, it would stop bringing warm waters to those areas.
Western Europe would get plunged into a deep freeze.
And so would North America.
Ice storms would rampage through Spain, France, Portugal and the UK.
London, among other cities, would be covered in snow for weeks.
The east coast of the U.S. would have a different problem -
rising water levels.
Normally, sea levels on the U.S. coast are lower
compared to those on the coasts of Europe.
That's because the Gulf Stream is warmer when it gets to Europe.
Take the Gulf Stream out of the equation,
and the water would push back toward the U.S.
That would disrupt agriculture in those areas,
drowning the economies that rely on growing and distributing crops.
And while the east coast of America
and Western Europe get chilly in their local Ice Age,
temperatures in the rest of the world would keep rising.
Climate change would trigger fires, tsunamis, and hurricanes -
all at the same time.
That would be a different world.
Nothing that the Earth hasn't seen before.
Except that this time, civilization would be disrupted,
and be left to deal with the changing climate
when the ocean currents decide to take a break.
What if one day our planet became so hot,
that the oceans ran away from it?
That's a story for another WHAT IF.