Isn't it beautiful?
Look at this cutie!
Well, enjoy it while you can because
if we don't act right now,
in less than 80 years,
we won't be able to appreciate it anymore.
Your great-grandchild will
will only experience it in books,
or by watching nature videos.
Isn't that scary?
Scientists predict that
the oceans' oxygen levels could drop
3 to 4% by the year 2100.
As that happens,
oceans will undergo
drastic losses of biodiversity,
and entire ecosystems could be wiped out.
Oceans losing 3 to 4% of their oxygen may
not sound very threatening,
but it's a big deal.
These massive bodies of water
cover most of Earth.
We know that
about 200 million years ago,
oxygen was depleted in the oceans.
This led to a massive extinction of species.
With oxygen levels dropping
in the oceans again,
could we face the same loss of ocean life?
And if you like to eat lobster,
shrimp, or fish,
will you have enough, or
any, to eat in the future?
"It's brook trout. Hope you like fish."
"I love it."
Speaking of food,
farmers use fertilizers that are
rich in nutrients.
Rains wash them into rivers, which
then carry them to the oceans.
In coastal waters and estuaries,
these extra nutrients
increase plant and algae growth,
and this is called eutrophication.
This causes an environment
with low oxygen, called hypoxia.
And when the oxygen's gone,
the water is called anoxic.
That leads to fish kills,
and dead zones that can't sustain life.
It can increase the oceans' acidity too.
Can you see what's happening?
It is a massive domino effect
with a deadly outcome.
And sea life
and biodiversity
are being hurt by it already.
Even today,
as the oceans' oxygen levels decline,
some male fish
are producing sperm
less capable of movement.
And low sperm counts
are not going to save our species.
"Wow, it really inks in here."
Some species, including the Humboldt squid,
are moving to new feeding grounds
where the water is oxygenated.
And that's a big problem.
The Humboldt squid
used to inhabit the waters
from South America to Mexico,
sometimes California.
But now, they've been found
off the coast of Alaska.
And so are the fish they feed on.
The squid are now competing for food that
that tuna and sharks typically feed on
in this area.
All this is disrupting the delicate balance
of the food web,
and will lead to massive amounts of
of fish loss and death.
Here's another problem.
Some sea creatures
would surface from the depths
looking for oxygenated water,
and eventually,
they would die caught in human nets.
Big fish would disappear first as
they need more oxygen to survive.
As this continues,
we'd likely have to say goodbye
to dolphins, whales, and
all of the beautiful mammals that
currently live in the oceans.
And as we said goodbye
to big fish like tuna,
many people would lose their food
and income.
Commercial fishing industries
are already struggling,
and will eventually close.
If you live on an island,
there's a limited amount of room
to grow crops and raise animals.
So many nations
depend on the oceans for food.
What would happen to Japan,
Indonesia, the Philippines,
or the Caribbean islands
if there were no more fish?
But what can we do to help our oceans?
Global warming
is one cause of deoxygenation.
Reducing our greenhouse
gas emissions is
is the one thing we can do, and
and need to do, to protect
our planet's ecosystems.
And the overuse of fertilizers
in agriculture
is something
that we should reconsider as well.
Do you want to know what else is
affecting our oceans?
Plastic.
Yeah, tons of plastic
is in the oceans.
And if we won't have fish to eat,
what would happen if we ate plastic?
Well, that's a story for another What If.