B1 Intermediate US 215 Folder Collection
After playing the video, you can click or select the word to look it up in the dictionary.
Loading...
Report Subtitle Errors
00:00:13,880 --> 00:00:17,851
In the 21st century, you don't have to
go that far for fresh water.

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.'
    You must  Log in  to get the function.
Tip: Click on the article or the word in the subtitle to get translation quickly!

Loading…

What If All the Sea Water Becomes Fresh Water

215 Folder Collection
Amy.Lin published on May 2, 2019
More Recommended Videos
  1. 1. Search word

    Select word on the caption to look it up in the dictionary!

  2. 2. Repeat single sentence

    Repeat the same sentence to enhance listening ability

  3. 3. Shortcut

    Shortcut!

  4. 4. Close caption

    Close the English caption

  5. 5. Embed

    Embed the video to your blog

  6. 6. Unfold

    Hide right panel

  1. Listening Quiz

    Listening Quiz!

  1. Click to open your notebook

  1. UrbanDictionary 俚語字典整合查詢。一般字典查詢不到你滿意的解譯,不妨使用「俚語字典」,或許會讓你有滿意的答案喔