Original subtitles

[narrator] Worldwide, 36 billion cameras are watching us.

On our streets, at work and in our homes.

They capture things that seems impossible.

Science says this shouldn't happen.

[man] Do you see that?

[narrator] Experts carry out forensic analysis

of these unusual events.

Wow. What a blast!

[woman 1 screaming]

This doesn't make sense.

There has to be some sort of explanation.

What else is going on here?

[narrator] Coming up...

A mysterious blast flash fries a noodle shop.

So what we could be looking at is some sort of covert demolition.

It's insane.

What could have caused that much destruction in a matter of seconds?

-[dog barking] -[narrator] In the forests of Canada,

have workmen stirred a legendary monster?

This is sort of like the ultimate werewolf.

Whatever is causing this change in temperament

-could be deadly. -[dog barking]

[narrator] And in the line of fire...

Wow! What is that?

An unholy flame burns across a sacred city.

That's not what you expect to see on a walk in the park.

-[narrator] Bizarre phenomenon... -Oh, my God. [gasps]

-...mysteries caught on camera. -[woman 2 screaming]

[narrator] What's the truth behind this

Strange Evidence?

Shanghai, eastern China.

May 29th, 2020.

It's mid afternoon at an unassuming noodle restaurant.

-Then... -[explosion]

...an enormous explosion.

Oh, wow.

[narrator] A passerby narrowly escapes

as the mysterious explosion rains debris onto the street.

This is clearly an intense blast.

The whole room is engulfed in flames.

[narrator] The restaurant is completely empty.

But staff from the shop next door flee

as the building burns.

This is like a fireball from Hell.

It's insane.

What could have caused that much destruction in a matter of seconds?

[explosion]

[narrator] Historian Tony McMahon

looks into the neighborhood where the video was shot

and discovers that even before it blew up

this venue was hot property.

This happened in the Jiading district of Shanghai

where there's been a lot of redevelopment.

[narrator] Shanghai has grown from a city

of 13 million in the 1990s

to a city of over 25 million people today.

But rapid expansion has come at a cost.

Two million people have been evicted

as single storied buildings are replaced by skyscrapers.

If your restaurant or house is in a redevelopment area

you've got two choices.

One, you can take the money they're offering and leave

or you can stay.

Which may anger a lot of people.

[explosion]

This explosion was, one, totally unexpected.

And, number two, took out the entire restaurant.

So what we could be looking at is some sort of covert demolition.

[explosion]

[narrator] Not everyone in China facing eviction wants to move.

And some residents fight back.

These buildings that resist the authorities

and property developers,

they're referred to as nail houses.

Because they're like a nail that won't be hammered down.

Some people will stay for years in these old apartment buildings.

No power, no running water, nothing.

Basically, every method is used

to convince the tenants to get out.

[narrator] These bizarre isolated dwellings

aren't just found in China.

The United States is also home to such houses

whose owners have stood firm

and refused to back down to powerful property developers.

You've got old houses around which have actually

been built large office buildings.

Perhaps like the worst case example,

there's this guy in Washington, D.C.

He refused to sell.

They even offered him $2 million to get out.

He just wouldn't do it.

So now the little two-story house

is surrounded by these massive office buildings.

Sandwiched on either side.

[narrator] But as some people have discovered,

staying put can be dangerous.

One old lady was literally buried alive

in the path of an excavator demolishing her own home.

And it really is demolition roulette.

Sometimes you get the money,

and sometimes you come to a sticky end.

So is this an attempt to remove a stubborn tenant?

[narrator] But when historian Craig Gottlieb

looks into the area where the blast happened,

he finds that criminal development enterprises

are not to blame for the explosion in the footage.

You know, the more you think about it,

bringing an organized crime to force eviction,

that's really a last resort.

And right now, around this restaurant,

there still exist other buildings, other restaurants.

So, really, it's not quite time to bring in the heavy guns.

[narrator] When former NYPD image analyst Coner McCourt

goes through the footage frame by frame,

he notices a strange light

just before the explosion.

Right here, dead in the center,

seems to be what could possibly be the point of ignition.

There's a yellow flash in the cooking area.

And what seems to be some kind of propane cylinder

that's possibly exploded.

[narrator] Fire is one of the biggest hazards in restaurant kitchens.

Propane is used in some restaurants

as it's more than twice as cheap as electricity

to heat up food.

But tanks in restaurants are designed

to stop their contents from exploding.

They use a pressure release valve

that stops pressure building inside the tank and blowing it up.

[gas hissing]

In principle, if the pressure release valve is working properly

the tank won't explode.

[narrator] Matt Kutcher has over 20 years' experience

as a top Hollywood pyrotechnics expert.

Go!

[narrator] And he immediately notices

that there's nothing wrong

with the propane tank safety valve in the clip.

So, you could see here in the footage, right?

That the canister's still intact.

So the other possibility is

maybe it's been leaking for quite sometime

and there's some kind of ignition source. Some kind of spark.

And then it just completely blew this place up.

[narrator] He wants to see if the blast in the footage

could have been caused by the propane tank

in the kitchen leaking.

So it's one thing to set up a gas leak,

but we're gonna have to set up a gas leak

in an area that's gonna be contained.

So we went ahead and set up a tent.

And this tent is gonna hold the actual liquid propane gas.

And then we're gonna have an ignition source.

In this case, we're gonna use a gas stove

to simulate the type of stove they may have in a restaurant, right?

Then when that source hits the gas,

hopefully, it blows up.

[explosion]

[narrator] Coming up...

We're gonna start letting it fill with gas.

[narrator] Matt Kutcher fries a restaurant.

[Matt Kutcher] Here we go!

In three, two, one. Hit it.

-[narrator] And fear in the forest... -[dog barking]

-[man] Hey! -Have workmen in the woods

stirred a legendary monster?

No, no, no, no! Oh, God.

[narrator] In Shanghai, China,

a noodle shop mysteriously explodes.

Pyrotechnics expert Matt Kutcher

wants to see if the explosion

was the result of a deadly leak in a propane tank.

He has rigged an experiment

where he will ignite leaking propane gas

inside a tent.

A contained area representing the restaurant.

[explosion]

Guys, here we go. I'm gonna open the valve,

we're gonna start letting it fill with gas.

[gas hissing]

All right, here we go. Let's get safe.

In three, two, one. Hit it.

[explosion]

Wow! That was really cool!

Man, that was great. There's nothing left.

[explosion]

It looks amazing.

You could see that all the gas

was building up there on the bottom, right?

And then all of a sudden it just explodes.

It just goes.

It looks like the video, right?

Big rolling fireball.

I'm pretty sure that was a propane leak that caused that explosion.

It must have been coming from that tank in the video.

It's a lot of gas, man.

[explosion]

[narrator] Propane tanks like the one in the video

are found in restaurant kitchens all over the world,

including the United States.

And just because the cylinders have a safety valve,

it doesn't mean diners are safe

from a lethal propane blast.

If fires like that start popping up,

I don't think I'll feel safe in a restaurant again.

It really raises the question,

could this happen to any of our favorite eating places?

[explosion]

[narrator] Now...

Northern Saskatchewan, Canada.

Near the hamlet of Stony Rapids.

September 9th, 2015.

A man is walking his dog in the woods.

-[dog barking] -His pet senses something is wrong.

[dog barking]

Then, he sees it himself

lurking between the trees.

What is this thing?

It looks massive.

-[dog barking] -[narrator] There's a giant figure

crouching close to the ground.

As though lying in wait.

There's no doubt it could take you down.

[narrator] Moments later the beast launches itself at the dog.

[dog barking]

No, no, no, no! Oh, God.

[narrator] The dog's bark turns from one of warning

to sheer terror.

-Its owner yells and drops his camera. -[dog yelping]

[man] Hey!

I don't blame the guy for dropping the camera

'cause this looked like it was going to kill his dog.

[narrator] The man and his dog flee.

[man panting]

This is a really terrifying clip.

If you were to see something like this in the woods,

you definitely better be running.

-[dog yelping] -[man] Hey!

[narrator] Saskatchewan's woods cover over

eighty-four million acres of the province.

Over twice the size of Florida

and are home to the Canadian timber wolf.

[howling]

But these wild creatures hunt in packs

and generally stay far away from human settlements.

Wolves are really species of the wilderness

and they're generally pretty afraid of people.

So it's very unusual to see them come

this close to where people live.

[narrator] Lyle Blackburn finds local reports going back centuries

of a huge canine creature in these woods.

European settlers called it the loup garou.

Legends describe a creature with formidable fangs

and incredible strength.

It wasn't just folklore.

Newspapers were issuing warnings to people

so they wouldn't be attacked.

It must have been absolutely terrifying.

[growling]

[narrator] Some believe the loup garou

truly was a supernatural creature.

Perhaps an evil man

transformed into a gigantic black wolf.

This is sort of like the ultimate werewolf.

If there's anybody out there who still does believe in loup garous,

I think they'll probably look at this footage

and think they've just seen one.

[dog yelping]

[dog barking]

[narrator] Chad Orzel examines the footage

and is reminded of a ferocious prehistoric creature

who is known to roam the woods of southern Canada.

Packs of giant animals called dire wolves

used to live in this part of the country

and they looked just like this.

[narrator] Dire wolves, so named for their aggressive nature,

hunted prey across North America

during the Pleistocene Epoch

over 10,000 years ago.

Dire wolves were built like modern grey wolves

but they were about 25% bigger.

If any of them were alive today

they'd probably be behaving just like this creature.

-[dog yelping] -[man] Hey!

[narrator] These terrifying mega-mammals

could take down a Mastodon.

But current science suggests

they became extinct at the end of the last ice age.

[puppies whining]

A project in Oregon has been attempting to breed canines

that look just like dire wolves since 1987.

These animals aren't real dire wolves.

They lack the aggression and ferocity of their ancient ancestors.

But could others be attempting to create the real thing

in the primordial forest of Saskatchewan?

That's the kind of experiment that could get out of hand.

[narrator] The revival of extinct creatures is no longer fantasy.

A team of scientists in the U.S.

are working on bringing back prehistoric species

by engineering hybrid ancient DNA

and implanting it into the egg of the animal's modern descendent.

Scientists are looking at bringing back the wooly mammoth

using its closest living relative, the Asian elephant.

[narrator] Biologists have no idea

how controllable or aggressive these creatures would be.

A study in 2021

found that so-called dire wolf skeletons

shared very little DNA with wolves, dogs or coyotes.

They were a totally unique prehistoric beast.

With no known living relatives

it would be incredibly hard to bring them back.

De-extinction science is still in its infancy.

Even when it is being handled by the top scientists.

It's highly unlikely that a successful rebirth

would happen outside of human knowledge.

So this must be something else.

[narrator] Orzel discovers disturbing reports

of modern wolves in the area

suddenly behaving in unnatural ways.

Northern Saskatchewan is a hotbed for wolf attacks.

There have been many sightings of wolves getting close to people

and sometimes even going on the attack.

[narrator] Northern Saskatchewan has had

three attacks on adult men in just 12 years.

One of them fatal.

In the rest of Canada,

there hasn't been a lethal wolf attack on humans for decades.

They seem to have lost their fear of humans.

Whatever is causing this change in temperament of the wolf

could be deadly.

-[narrator] Coming up... -[dog barking]

Man exploits the forests,

wolves get angry.

So what's going on in this region

that could be setting these wolves off?

[narrator] And a meteorite in a museum

seems to levitate a glass case.

Why is it moving the way that it's moving?

It's just... It has a will of its own.

[narrator] In northern Saskatchewan, Canada,

eerie footage shows a man and his dog

-confronted by an aggressive creature. -[dog yelping]

Biologists think it's one of North America's 60,000 wild wolves

displaying unusually hostile behavior.

[snarls]

Their very large size makes it extremely difficult

for a human to win a fight against them.

But normally, humans wouldn't have to worry

about getting attacked by a timber wolf.

[narrator] Reports have been growing in the region

of wolves losing their fear of humans and going on the hunt.

In 2004, a worker is heading home

when he is savagely attacked by a wolf.

He suffers severe bites to his back, arm and pelvis,

before being rescued by colleagues.

Then in 2016,

a local security guard discovers a crazed wolf

with its jaws around the neck of a kitchen worker.

So what's going on in this region

that could be setting these wolves off?

[narrator] Researchers studying wolf attacks

on Vancouver Island, western Canada,

believe the problem is people.

Over a six year period,

they recorded 51 dangerous wolf encounters

including seven dog fatalities.

And it's a trend seen across Northern America.

[dog yelping]

That dog is lucky to get out alive.

[narrator] Industries like mining, logging and tourism

are pushing communities deeper into the wilderness

bringing more humans into contact with wolves.

And man's invasion of this wilderness may only get worse.

Since the end of the 20th century,

over ten million acres of Saskatchewan's land

has been appropriated for commercial use.

While more than quarter of a million tourists

visit this area every year.

As wolves observe humans up close,

they lose their fear of us

and see us instead as a feast.

It's certainly possible that that's what we're seeing in the video.

[narrator] The message is clear.

Avoid close contact with wild wolves.

If you started trying to run from this thing, forget it.

You'd never make it.

You can never outrun this thing.

[dog yelping]

[narrator] Now, Chelyabinsk, Russia.

February 15th, 2013.

A meteor streaks across the sky.

[Tony McMahon] And then when it impacts,

it creates a sonic boom

and smashes windows in houses,

injures 1,600 people.

The rock was pulled from the local lake

and put on display in a museum.

[narrator] The 1,100 pound meteor fragment

becomes the star attraction

at Chelyabinsk museum of South Ural History.

Six years later,

a security camera monitors the display.

The meteorite is protected beneath a glass pyramid casing

that's on four steel motorized rods

which can be raised or lowered by museum security staff.

It looks like any old day at the local science museum.

Nothing really special's going on.

You have a few visitors.

They're reading some of the text panels.

[narrator] But then...

Wow!

It looks like the glass case is floating.

[narrator] Footage sped up 16 times

shows the security dome weighing over 250 pounds

slowly rising on its metal rods

five inches into the air

seemingly without any human intervention.

any human intervention.

It's really inexplicable.

You've got this meteor under a glass case,

and then the case just seems to lift of its own volition.

[narrator] It's occurring so slowly, the visitors don't even notice it.

But the footage shows it's happening

and experts are baffled.

Why is it moving the way that it's moving?

It just has a will of its own.

[narrator] The case is designed so staff can retrieve the rock

but no one was attempting to access it when the footage was shot.

You see the staff, they're looking and trying to decide what to do.

So what's going on with this strange rock from outer space?

[narrator] People in ancient times believe meteors possess strange and magical powers.

These massive objects light up the sky with awesome power,

so it's no surprise that they were worshipped in ancient Egypt,

in ancient Rome even.

At Islam's holy shrine in Mecca

some believe there's a meteorite which forms the centerpiece of devotion

and it's believed to date back to Adam and Eve and it was

placed there by the prophet Muhammad.

[narrator] Modern day scientists have found that some meteorites do have powers

that would have startled the ancients.

They can have magnetic fields

especially when they contain a lot of iron or nickel.

But the magnetic power of even the biggest meteorite

is usually only strong enough to move the needle of a compass.

Not enough to lift a glass case like the one in the clip.

So what is it about this exhibit that's exerting that power?

[narrator] Coming up, is something alive inside this meteor?

It could possibly, completely suffocate all of living life,

killing out everything we know on this planet.

[narrator] And experts are baffled by a mysterious big nose beach blob.

It's body is translucent

and you can almost see something.

Maybe its organs moving around inside?

[narrator] In Chelyabinsk Russia,

a museum security case protecting an 1,100 pound meteorite

mysteriously opens.

Engineer Nick Householder wonders if the Chelyabinsk's meteor

could contain a hidden visitor.

NASA and science fiction writers have long considered

the possibility of life hitching a ride inside of a meteorite.

Because you have effectively a ready-built space craft

with the shell protecting you from the forces of space

while providing you sustenance inside.

[narrator] The Chelyabinsk's meteorite fragment has been

extensively studied by scientists

and no space craft has been found inside.

But astrophysicist Athena Brensberger

reckons they might have missed an almost impossible to spot type of life form.

[Athena] A possible alien life form could exist within a meteor.

It may live in something known as a microscopic shadow biosphere

which would look so different than anything that we've known here on earth

that we might not even think that it'll be biological in origin.

[narrator] Scientists believe these theoretical shadow organisms

utilize radically different chemistry

undetectable by regular tests.

Life on earth is carbon-based,

but in 2016, a team of Caltech scientists

engineer a bacterial enzyme

that can make organic molecules out of silicon.

A silicon-based life form might look more like a rock

than anything we recognize as a creature

but would nevertheless still be alive.

Perhaps this meteorite has some type of life

that itself is what's effecting the moving of the case.

Maybe that's why the museum staff are so scared that it's opening.

That case could be there to protect us.

[narrator] A silicon-based life form would need some kind of food for fuel.

It could hunt out energy sources from chemicals on our planet

then digest, process and excrete them in a way that could

catastrophically alter the environment.

If something like this were to reach earth,

it could possibly, completely suffocate all of living life

killing out everything we know on this planet.

[narrator] But Tony McMahon thinks the mysterious movement of the glass

could be evidence of an audacious attempted theft.

Pound for pound, these meteorites are worth more than gold.

So, you have to wonder

how much the meteorite in the museum that we saw on the footage

would go for, arguably millions.

[narrator] Former FBI agent Rhonda Glover looks at the

mechanism that lifts the glass case

and sees a clue.

The security guard comes at and he has the remote

and then the case goes back down.

Something caused the case to go up.

So the question would be if the staff have the remote

how could somebody else open the case?

[narrator] Aerospace engineer Nick Householder thinks the

wireless remote control mechanism

is a weak point in the meteor museum's security system.

I wanna see if it's possible to steal a signal and use it for nefarious purposes.

But instead of a display case...

[beeps and clicking]

I'm gonna see if I can steal this car.

[narrator] Car keys use the same principle as most remote control devices.

In modern contactless car keys emit a constant signal

so the owner can unlock their car

just by being in close proximity.

Modern car keys are effectively a tiny radio

they broadcast signals directly to your car

to open your car doors, sometimes to start the engine.

If you're capable of capturing that signal and then repeating it,

you can effectively hack into a car.

[narrator] Householder has an electronic device

that will attempt to steal the car key signal.

For safety, the design must remain secret.

Let's see if we can use this to open the car which might explain what we're seeing

in the case in video.

[narrator] Next, Householder move closer to the key fob

to try and steal the signal.

Now that we're a little closer let's see if we can actually capture the signal.

When I turn it on, it begins the seeking process.

-[beeps] -There, we got it, it captured the signal.

Let's see if we can open the car.

Now that we've stolen the signal, let's see if we can open it.

Now just to prove it, this is still locked.

When I send out the signal I've stolen...

[unlocks]

The doors unlock.

I'd be willing to bet the technology like this could be the explanation

for what we're seeing in the video.

[narrator] McMahon finds Chelyabinsk

has a very active criminal gang.

An offshoot of a big crime enterprise run across the Urals.

They use similar devices to hack remote control keys

and steal luxury cars.

Could we be seeing Russian gangs using the same remote control technology

that they employ to get their hands on American luxury cars

in order to steal that very valuable meteorite?

[narrator] And why stop at space rocks?

There are over 50,000 museums in the world,

crammed with dinosaurs, skeletons, jewelry and other ancient artifacts

with a total insurance value of 180 billion dollars.

If they Russian mafia are capable of deploying

high tech criminal techniques in our museums and art galleries,

they could make a lot of money.

[man] We're talking about the Russian Federation

where there are organized gangs that are out there to turn a profit.

What would stop something like this from happening somewhere else?

[narrator] Now, Koh Lanta Beach, Thailand.

March 31st, 2018,

a tourist is walking along the beach

when he comes across a mysterious blob.

Gadzooks!

That is gross.

It's brown with a greasy sheen

and unlike normal blob-like sea creatures,

it appears to have a snout.

It's writhing and moving and palpitating.

Not a pretty sight.

[narrator] And there seems to be some kind of unnatural movement

going on inside the blob.

It's body is translucent and you can almost see something,

maybe its organs moving around inside.

[narrator] The tourist begins to touch it then quickly changes his mind.

Oh, I would not touch that.

I wouldn't touch that.

This thing is unlike anything I've ever seen before.

[narrator] Coming up, is this blob a man-made monstrosity?

There's every possibility that our household waste is creating

alien-like mutated creatures from the depths of the ocean.

[narrator] And in a Spanish town

a bizarre streak of fire charges across the grass.

Is this an artificial fire or a weird natural phenomenon?

[narrator] In Koh Lanta, Thailand a weird blob

appears to have a snout and something seems to be writhing and moving inside.

Marine biologist Eric Hovland wonders if the creature could have mutated

due to some industrial accident.

Mutations can be caused by a whole host of different causes.

There's every possibility that this creature could be affected

by local pollution as well.

[narrator] Thailand's coastal provinces generate almost three million tons

of uncollected garbage every year.

Waste from tourism, agriculture and industry

blights this once idyllic destination.

Thailand is known for its beautiful beaches and pristine waters

but pollution is having an environmental impact of unmeasured proportion.

[narrator] It's surrounding seas contain waste

that ravages all living creatures.

In 2017, fishermen sail into a mass of plastic trash

floating in the Gulf of Thailand. It weighs over 90 tons.

The media dubs it Garbage Island.

The chemicals that comprise the plastics can be toxic,

leading to cancer and mutations.

Marine creatures are particularly susceptible to mutation

because they're simply bathed in pollution

and have no means of escaping what they eat, breathe and swim in.

[narrator] The organism's snout could be some sort of breathing tube,

a bizarre feature for a creature like a blob

designed to live on the ocean floor.

There's every possibility our household waste is creating

alien-like mutated creatures from the depths of the oceans.

[narrator] Biologist Raven Baxter tries to pinpoint the creature's species.

The long shape is typical of a sea cucumber.

But this one is difficult to identify.

[narrator] It's unlike any ordinary sea cucumber

in which movement is normally limited.

One of the challenges in identifying this sea cucumber is

sea cucumbers are very simple organisms.

However, we see a lot of motion and writhing

inside this particular sea cucumber.

This pulsating suggests the presence of a second creature inside.

[narrator] Baxter believes the this second organism could be

one of the nastiest fish in the ocean.

These fish are disgusting.

They burrow into the sea cucumber's anus

and live in there like it's a cave.

[Steve] During the day, they use it as a hidey-hole,

and at night they come out to hunt.

It's not the kind of living arrangement I would personally go for.

[narrator] These fish are called pearl fish

and sea cucumbers with guests like these living inside them

can suffer a hideous fate.

In some cases the pearl fish will eat the sea cucumber's gonads.

[narrator] On other occasions pearl fish have been known to

burrow so deep inside sea cucumber's

that they penetrate their vital organs.

What looks like the snout may actually be the fishes head poking out.

[narrator] But if this is a pearl fish setting up camp inside a sea cucumber

its behavior is very strange.

When the man who shot the footage tries to put the creature back in the sea,

it pushes its snout-like bulge out of the water

as thought the ocean isn't where it wants to be.

What does the sea cucumber want to remain on land?

[narrator] The next day, the mysterious pulsating blob is gone

and so is any chance of figuring out what it could really be.

Mutant creature, or rare aquatic species,

it certainly qualifies as one strange alien blob.

[narrator] Now, Calahorra, Spain...

May, 2020,

a man films as a relentless flaming wave

sweeps through a public park.

Wow, what is that?

This persistent line of fire

it just marching across the park unhindered.

[man] It's really ominous, it's almost like nothing is gonna stop this

slow creeping blaze that just snakes as far as the eye can see.

[narrator] And the bizarre blaze doesn't seem to burn

like any ordinary fire.

The white stuff almost looks like snow.

So we've got fire and ice together. It's unreal.

[narrator] But it can't be snow as the temperature is 68 degrees.

And nothing else about this blaze seems to make sense either.

The trees aren't getting burned. And the wind is moving consistently against the fire.

[narrator] And most bizarre of all, as the weird white stuff burns,

it leaves pristine grass behind.

It's like a biblical fire cleansing the land.

Fires don't just crawl across a public park like that.

Is this an artificial fire, or a weird natural phenomenon?

[narrator] Coming up...

Is a killer substance taking over our parks?

It's amazing that something so harmless could be so lethal.

[narrator] In Calahorra, Spain...

A man films a miraculous-looking strip of fire

spread across a local park,

leaving pristine green grass in its wake.

Engineer Rachel De Barros discovers local farmers use strips of fire to clear fields

because it's fast and cheap.

But these flames come with severe consequences.

The effects of stubble burning can be devastating,

because it fills the air with fine, particulate matter.

In essence, you're dumping a ton of pollutants into the nearby city.

So people start to suffer all kinds of health concerns.

[narrator] When farmers burn stubble,

fine particles, over a hundred times thinner than a human hair,

are released into the atmosphere.

They are the most dangerous form of air pollution,

because when breathed in,

they penetrate deep into the lungs,

increasing the risk of mutations and cancer.

When they enter the bloodstream,

the smoke fumes can cause heart disease and strokes.

And research by the European Environment Agency

has connected almost 28,000 deaths in Spain to particulate pollution.

In Europe, this practice is all but banned,

and only allowed in special circumstances.

But it still happens. Sometimes legally, and other times not.

[narrator] In September 2019,

a man is arrested for unauthorized stubble burning

near a local park in Gran Canaria.

These fires can't be controlled, only contained.

So it's not hard to imagine it spreading beyond the park, into the town.

[narrator] But stubble burning doesn't explain

what the mysterious white substance is.

And why the flames leave pristine grass behind.

Biologist Kiki Sanford studies the trees in the footage

and suspects they play a crucial part in this bizarre blaze.

Looking at the shape of the trees

and the color of the bark and the leaves on the trees,

I think these are poplars.

[narrator] Poplar trees, also known as cottonwoods,

grow at a rapid rate of approximately six feet a year,

and are a popular source of biofuel.

These trees are so useful in providing green energy,

that the timber industry

has doubled the area of poplar plantations in the last 15 years.

Now covering 23 million acres around the world.

But these beneficial trees have a hidden danger.

Every spring, these trees produce seeds that are covered in white cotton-like hairs.

When there are lots of these poplar trees in one area,

the seeds can make it almost look like snow.

But what's really shocking is just how flammable these seeds really are.

[narrator] The fine fluff burns quickly.

Just one spark, and fire rapidly spreads across the ground.

Just like the blaze in the footage.

Wildfires are a major problem in the modern world.

And in some cases, these seeds are exacerbating the problem.

[narrator] In June 2019, firefighters battle a devastating wildfire

that rages across a forest in Winnipeg, Canada.

They discover that the fire could have been spread

by large amounts of this poplar fluff.

They had to collect the fluff to minimize the damage.

[narrator] And environmental scientists have found a worrying trend.

The conditions that are perfect for wildfires

also drive an increase in poplar seed production.

Droughts from previous years causes these trees to panic

and produce more seeds, just in case.

It's like they're trying to prepare the next generation of trees in case they die.

Droughts are painful at the best of times.

But introducing a highly flammable substance is adding insult to injury.

[narrator] Poplar accounts for 50% of all timber cut in some parts of Spain.

And fires in the country are skyrocketing in numbers and intensity.

In 2019,

a fire roars through northern Spain,

on an unprecedented scale, not seen in the country for 20 years.

The Regional Interior Minister reported that a fire would burn out 50,000 acres.

People were evacuated from their homes, roads were closed,

and over 500 firefighters were sent in to battle the blaze.

Hundreds of sheep die in the smoke and the flames.

It was just insane.

[narrator] The mayor of Calahorra

suspects the freak fire in the footage was started on purpose.

She believes that it was caused by careless human activity.

Or someone deliberately lighting it just to see the effect.

[narrator] Luckily, on this occasion, the grass beneath was wet and didn't burn.

Had it been dry, this fire could've destroyed the entire city.

The risk is if the fire doesn't move, but stays confined in one place,

it can light trees and houses and burn in an uncontrolled devastating fashion.

[narrator] Spain, where summer temperatures soar to over 100 degrees Fahrenheit,

is at risk of drowning in a sea of flammable fluff.

This fluff on the ground is like gasoline in an already vulnerable area.

This is not a good spot for a picnic.

Unless you want your sandwich flambéed.