on this slimy beach?

Well, what if most of our beaches

were starting to look like this,

because our oceans were quickly being

taken over by this green sludge?

This isn't nuclear waste

people are swimming in,

it's algae!

And if it took over all our oceans,

it would change a lot more

about our lives than just how we vacation.

The idea of algae taking over

the entirety of our oceans may seem

a little far-fetched, but it's already taking over

smaller bodies of water around the world.

When algae grows densely and out of control,

it's called an algal bloom.

And in 2019 there was an algal bloom so large it could be seen from space!

Not only did it look really gross,

but it was also incredibly dangerous,

since it produced toxic effects for both animals and humans.

But despite all the danger involved, if algae took over our oceans,

it could also do wonders for our planet,

as it would quickly become our biggest weapon against climate change.

And that leaves us with a dilemma.

Should we fight the algae's take over?

Or embrace it?

Before we can answer that question,

we're going to have to become a little more acquainted with the green stuff.

Say hello to algae.

You may only know it as the weird green stuff that grows on rocks,

but there's a lot more to it.

Algae is an informal term for a large, diverse group of aquatic organisms

that have the ability to conduct photosynthesis.

They can occur in a variety of forms and sizes,

from single microscopic cells to seaweeds.

And if they took over our oceans,

they could provide a much-needed helping hand in our fight against climate change.

No matter what trees or plants try to tell you,

algae is the real master of photosynthesis.

It provides more than half the oxygen in our atmosphere via phytoplankton and seaweed,

and it consumes more carbon dioxide than trees.

While trees take generations to mature enough to really make a dent in carbon concentration,

algae grows quickly,

and spreads widely,

giving it the potential to be even better at absorbing

and consuming carbon than our woody friends.

And algae isn't just good for cleaning the air.

Some kinds of algae can also provide food for marine life,

food for humans,

and be used as nutritional supplements.

But perhaps the most intriguing possibility of a world with algae-filled oceans

is how algae could be used to replace some of the most harmful products on our planet,

like oil-based plastics.

Some of the biggest oil companies are now researching whether

algae can be used as a sustainable fuel source,

as some researchers think it might be possible to produce 19,000 liters (5,000 gallons)

of biofuel from a single acre of algae in one year.

So if we had entire oceans of this stuff,

we could do a lot of good for the planet

by reducing our use of fossil fuels,

and by removing some contaminants from the air.

But keep in mind that our oceans are gigantic, and

filling them with green sludge is bound to have some negative effects

on the species that rely on them.

Large masses of algae can block out the sunlight for smaller organisms

living near or under it, causing aquatic plants to die.

And once the aquatic plants are gone, the fish,

shellfish and other marine animals that eat them would follow closely behind.

Harmful algal blooms, such as brown or red tides and blue-green algae,

can contaminate public water supplies,

or can accumulate in the bodies of smaller aquatic animals

that are consumed by larger ones,

resulting in illness or death in whales,

sea lions, otters and manatees, among others.

People who eat shellfish containing dangerous algae

can suffer diarrhea, seizures and even death.

So if we want to harness all the positive impacts of algae,

there might be a better option than allowing it to take over our oceans.

Maybe we could farm algae in land-based facilities instead.

We obviously wouldn't be able to produce an oceans' worth of algae,

but we could still provide material for other uses without

depriving fish and other vegetation of sunlight.

With the help of algae,

maybe we could even double the amount of oxygen in our amosphere.

But you know that's a story for another WHAT IF.