But still, supply is running out.

What if a trip to the well, and a trip to the beach

were one and the same?

This is 'What If,'

and here's what would happen if all sea water became fresh water.

The first big question we have to ask is,

Well, it wasn't always like that.

About 3.8 billion years ago,

Earth's surface had finally cooled to the point that water vapor turned to liquid;

no salt added.

That's right! A really, really long time ago, the oceans were fresh water!

But that wasn't going to last.

Whenever it rains, carbon dioxide from the air dissolves into the falling water.

This makes the rain slightly acidic, and when it falls, it causes rocks to erode.

From there, rainwater slides towards nearby rivers and streams,

taking loose salt and minerals along with it.

From there, this runoff flows from rivers into the ocean.

Add to that any additional salt and minerals

that would be expelled from hydrothermal vents or submarine volcanoes,

and then consider that this whole process

has been recurring more or less consistently for 3.8 billion years.

That's a lot of salt!

In fact, there's so much salt in the ocean,

that if you spread it evenly across all the land on Earth,

it would amount to one towering layer of salt that's 40 stories tall!

And we've got to assume it's for a reason.

Freshwater oceans sure do sound like a godsend.

A sea without salt would decimate marine life

and dramatically affect our weather and temperatures,

making human life on Earth very difficult, if not impossible.

and as many as 2 million more to be discovered.

But if the ocean were to become desalinated, we'd never find them.

Saltwater fish, and other ocean creatures

evolved to be able to drink salt water to stay hydrated,

and get rid of excess salt.

Not all sea creatures do this the same way, but,

being able to pump out excess salt

is crucial to surviving in the ocean.

Some species, like salmon, have adapted to tolerate fresh water and salt water.

But for the most part, all saltwater species would perish.

This includes underwater algae, which,

believe it or not, accounts for half the photosynthesis that occurs on Earth!

Photosynthesis plays a vital role in supplying our planet with oxygen.

Since trees and plants convert carbon dioxide from the atmosphere into the air we breathe!

So without algae, not only do we get less oxygen,

we also have a lot more carbon dioxide in our atmosphere!

This intensification of the greenhouse effect

would make some parts of the world unbearably hot.

You'd definitely notice this intense heat near the equator,

since our ocean currents wouldn't be

circulating warm water and air the way they used to.

Convection currents help warm water from the equator get farther north,

while colder water from the north is able to cool hotter areas down south.

At the equator, warmer water can carry more salt,

so this denser water sinks lower, while cooler water flows over top of it.

And in the far north, the water gets cold enough to freeze and form sea ice.

Salt gets left behind as the water freezes,

and naturally, this makes colder water up north denser,

allowing it to sink to the bottom to make room for the incoming warmer water

that's worked its way up from the south.

Without salt, the whole process breaks down.

Earth's extremities would freeze, while weather around the equator would intensify.

For one thing, hurricanes would be a lot more frequent,

and a lot more deadly!

At this point, our weather and our climate

would be totally different from how we know it now!

How long would we survive to see all these changes?

Not long at all.

You'd either freeze, overheat,

die in a natural disaster, or starve to death!

Yeah, with significantly less photosynthesis,

and climates that are either extremely cold or extremely hot,

our weather would no longer support the diverse plant life it has now.

The entire food chain would collapse.

Most species would die off, including humans,

since crops we rely on for sustenance would all disappear.

So, when we say ocean salinization is important,

don't take it with a grain of salt!

Of course, we respect the scientific method,

so keep questioning the world and its properties, on land and beyond,

and come back soon, for another 'What If.'