Nature

NARRATOR

We live on a restless planet. Every day on Earth, around 30 volcanoes violently erupt. By exploring the planet's most active volcanoes today...

DR. MARLOW

This is amazing.

NARRATOR

...we discover how they hold the secrets to the origins of life... ...how they continue to shape our planet...

DR. GIAMANCO

Without volcanoes, there wouldn't be life on Earth.

NARRATOR

...and how life has adapted to thrive in their shadows.

PORTER

It's a destructive force, but it's also a force that makes life possible.

NARRATOR

Volcanoes are not just forces of destruction. They are the life blood of our planet.

Theme plays

NARRATOR

Our world is bursting at the seams. There are hundreds of active volcanoes on Earth, each one capable of exploding with little warning. At any one time, up to 30 of these active volcanoes are in an eruptive phase. Viewed from space, patterns begin to emerge. One of the most active volcanoes is in the southwest corner of the Pacific, in the island nation of Vanuatu. This tiny archipelago is home to a very special volcano. Producing more poisonous gas than almost any other volcano in the world, Marum is a sight to behold. And at its heart is a rare lake of lava. The conditions here have attracted biologists Dr. Jeffrey Marlow and Dr. Jens Kallmeyer to conduct a pioneering expedition.

DR. MARLOW

So we're in the Vanuatu island arc. It's a chain of active volcanoes, many of them. We can see some amazing volcanoes off this way. We're on an island that has two very active ones and we're going up there right now.

NARRATOR

Jeff is going to descend into the crater to search for extremophiles, micro-organisms that are some of the toughest forms of life on Earth.

DR. MARLOW

I study life in extreme environments, but this is certainly the most extreme environment I've been to. This is my second expedition to Marum, but I have no idea what to expect. Entire cliffs can fall away or be created. The landscape inside the crater is constantly evolving.

DR. KALLMEYER

Wow. Holy crap.

DR. MARLOW

This lava lake is going like crazy!

DR. KALLMEYER

I'm a geologist for 20 years, but I've never seen anything like that.

NARRATOR

Lava lakes are rare. Only a handful of volcanoes in the world host active pools of lava like this. Two hundred feet wide, it's a giant gateway to the planet's beating heart. What the team finds here could change the way we think about the extremes of life on Earth... ...and could also help us understand the likelihood of finding life elsewhere in our universe.

DR. KALLMEYER

Heck, this is where we are about to camp!

NARRATOR

This small camp is going to be home for the team for the next few days.

DR. MARLOW

Home sweet home.

NARRATOR

Meeting the scientists on the summit is expedition specialist Chris Horsley. Chris is an expert in rope access and rigging. He's climbed in some of the world's most dangerous environments. He's been on top of the volcano for a week, setting up lines and anchors, ready for the journey to the bottom of the crater. He wastes no time in getting everyone together to discuss the challenges ahead.

HORSLEY

Essentially, guys, everything up here is trying to kill you. We've got volcanic shards of glass flying through the air, acid rain, sulphuric clouds, and a 400-meter vertical cliff that if you fall off, there's no return. Our rigging place is just over here. That's going to be then a 200-meter rappel, and we can find our best anchor point to re-anchor our ropes that are going to take us all the way down to the bottom and to the boulder field that's located over here.

DR. MARLOW

Our main goal of being here is to see if there's any life inside the crater, and when we do get down to the bottom, how close do you think it is possible to get?

HORSLEY

If any point, I think it's too dangerous, or I'm worried about your safety, I'm gonna pull the pin and take you out of there. This is one of these rare examples of something that is so vicious and so angry that more people have been in to space than have visited this insanely magical place.

DR. MARLOW

So after our safety briefing, I feel a little bit more nervous than I might have been. We're going to be sampling as we kind of approach the lava lake itself, and we want to know when life stops, when it's too hazardous for anything to survive. The samples we're after are extremely rare and they're gonna tell us, hopefully, some really important things about the way life works and the possibility of how life could exist elsewhere in our solar system. So I'm hoping we can do all that. Do it in a safe way and kind of meet the time constraints that we have.

NARRATOR

The team settles into camp and starts preparing for the descent. Earth's volcanoes are not limited to far-flung tropical islands. Erupting volcanoes are found on every continent. And while Marum continues to erupt, one of the planet's largest volcanoes rips the Earth into pieces on the southern edge of Europe. Mount Etna has been erupting for around half a million years......and like Marum, it might hold precious clues to how Earth became a planet fit for life. It ebbs and flows...from periods of relative peace......to catastrophic eruptions that threaten the lives of those that live closest. Yet for some, living here is a gamble worth taking.

Birds chirping

NARRATOR

The soil created by Etna's eruptions produces some of the richest agricultural land and finest wines in the whole of Italy. The unique way of life on the slopes of Europe's most active volcano is what drew Dr. Salvo Giamanco here. It's his job to help predict Mount Etna's next move.

DR. GIAMANCO

Most of the people living here see Etna as a Mother, and like all mothers, she gives us life, through the vegetation, the plants. But like all mothers, she, you know -- sometimes she slaps us in the face, and she reminds us of the rules that are in this environment.

NARRATOR

Most of the year, Etna de-gasses......and the gas offers precious clues to what's happening inside the volcano.

DR. GIAMANCO

You can think of an eruption a bit like the opening of a Spumante bottle. Before opening it, you don't see the gas. It's a liquid that stays there without showing signs of any activity. But once you start to open the bottle, You'll see the gas suddenly forming bubbles, and those bubbles will give the final energy to the magma to rise to the surface and eventually erupt. So the gas is the real engine of eruptions.

NARRATOR

As gas drives volcanic eruptions, Salvo and his team are today trying to determine how much is coming out of the volcano. Different types of gas are released when the magma rises to certain depths. An increase in particular gases could mean that magma is racing towards the surface. And this close to the volcano, even a small eruption could have deadly consequences.

DR. GIAMANCO

There are many risks when working here. The gases, they are highly corrosive. And also we are on the rim of the central crater, where an explosion may occur at any time.

NARRATOR

It's a race against time to get the data and get out.

DR. GIAMANCO

Each time the gas passes in between the infrared source and the sensor, we get a lot of dips in our spectrum, each one corresponding to a specific gas species and each one giving us the concentration of that specific gas species.

NARRATOR

Today, the team doesn't see any drastic changes in the level of gases, yet there is one gas in the data that is more important than nearly any other.

DR. GIAMANCO

So we see carbon dioxide, we see chlorine, we see fluorine, we see sulphur dioxide. But the most important one is water vapor. From its liquid state to its vapor state, it increases its volume by 1,000 times.

NARRATOR

Water vapor is a driver of volcanic eruptions, and on any given day... Mount Etna releases hundreds of thousands of tons of it into the atmosphere.

DR. GIAMANCO

So every time a volcano erupts, every time a volcano breathes, it emits this life-giving gas.

NARRATOR

The origins of water on Earth have been debated by scientists for hundreds of years. Some believe that water was delivered by comets, but recently, there has been mounting evidence for a different explanation. To explore this theory, we have to wind the geologic clock back 4 billion years to a time when the Earth was hot and still forming. The idea is that water has always been on Earth. Trapped beneath the crust, it's locked in liquid magma. But as the Earth's surface began to cool and harden... ...volcanoes acted like a tear in the fabric of our planet, allowing the water to slowly escape. This water vapor then condensed in our atmosphere and fell as rain. It rained for so long that eventually our dry, barren Earth turned into a Blue Planet.

DR. GIAMANCO

Water that we see on Earth mostly comes from volcanoes. Without volcanoes, there wouldn't be life on Earth. Literally.

NARRATOR

As the sun sets in Italy... it's slowly rising in Hawaii. One of the most remote island chains on Earth is continuing to be transformed by the raw power of the planet. It's the perfect place to explore how the interior of Earth shapes life at the surface. Kilauea is the most active volcano in the United States. Its summit crater is large, but it's not necessarily the most dangerous part of the volcano. The giant flank eruption in 2018 was the most devastating in 200 years. As the volcano's main crater collapsed, millions of tons of lava drained through a series of underground tunnels... ...emerging in the heart of a residential community. Seven hundred homes were buried beneath molten rock. And 2,000 people were evacuated. Forests burned and fragile ecosystems were destroyed. Amazingly, no lives were lost. But the recent outbreak in Hawaii is just the latest in a long line of land-creating eruptions. Hawaii was formed by a hot spot of magma beneath the Earth's crust. As the magma reached the surface, volcanoes broke out, creating islands. Over time, the tectonic plate on which these islands sit slowly moved, and new islands were created over the hot spot. The island chain we see today is 6 million years' worth of eruptive activity. And it's still creating new land today. Despite the obvious destruction caused by the volcano, it may be having surprising, positive effects on the ocean ecosystem. Following the recent eruption, scientists from the University of Hawaii saw giant phytoplankton blooms, colored here in blue on images taken from space. Could this have been caused by the volcano? Lava is rich in phosphate and iron, elements that act as fertilizers. In the enriched waters, phytoplankton exploded. Phytoplankton is fed on by larger zooplankton... ...which in turn provides food for larger animals. And nighttime is feeding time. When plankton abundance is high, it draws in huge sea creatures. Ocean giants... like manta rays. They come each night to feed on plankton migrating up to the surface from the depths. Swimming with their mouths wide open, they scoop in water using their modified front fins and filter out the tiny plankton. At the richest feeding sites, they barrel roll to stay within these nutritious plumes. A single manta can consume up to 50 pounds of plankton in a single night. Back in Vanuatu, rain has started to fall. It's an unwelcome complication to the challenges that lie ahead and bad news for the descent.

DR. MARLOW

So Marum crater is the world's largest point source of sulphur dioxide. That sulphur dioxide mixes with water in the atmosphere and makes sulphuric acid. When that rains down, you're being bathed by acid. The same thing that makes our descent possible, the idea of this kind of this nice line down into the crater is the same thing that makes it hazardous. It's where all of the water goes when it rains. So you're gonna have acid rain pushing rock and sediment down this water course at us, at our ropes. We need to wait for a really good day to make the full descent.

Teakettle whistling

DR. MARLOW

NARRATOR

Later in the evening, Jeff uses a thermal camera to find the best sampling location in the crater.

DR. MARLOW

Wow. That is insane.

NARRATOR

The imagery on the camera gives Jeff information on where he should be looking for the extremophiles.

DR. MARLOW

The lava lake there is off the charts, literally. It's too hot to actually read with this camera. This spot right up here around that plain that we've seen could be really appealing. There are a lot of rock faces that are facing the lava lake and getting a lot of that heat off of the molten rock. That's probably a high priority spot to go to. To imagine that tomorrow I'm headed down there is kind of terrifying. I would say this is probably one of the most inhospitable places on the planet, umm... It would be pretty remarkable to me if there's actually life down inside the crater.

NARRATOR

As Marum continues to light up the night sky in Vanuatu... It's the middle of the day in the heart of Africa, and it's burning up with geologic activity. Three of the planet's 30 erupting volcanoes are found here. One of the tallest and most active volcanoes in the region is Ol Doinyo Lengai. But far from causing devastation, the eruption here is just what this ecosystem needs. While most volcanic ash is full of silicates, the ash from Ol Doinyo Lengai is loaded with carbon and minerals. As the ash rains down, it transforms the grasslands into a uniquely rich, nutritious pasture. After millions of years of volcanic activity, the area has become a vital stage on the annual wildebeest migration. The lush pasture is a giant nursery that draws in animals from all over the Serengeti ecosystem. More than a million wildebeest alone are nurtured by the nourishing grass that grows in the shadow of the volcano.

Wildebeest lowing

NARRATOR

A lot of the planet's volcanoes can sit dormant for centuries before explosively erupting. Life can become desensitized to the risks they pose. It's a dangerous game, considering we live on a relatively thin crust of rock wrapped around a molten core of magma. Ecuador is home to a number of volcanoes that can erupt with little warning. Cotopaxi is one such giant. Rising above 19,000 feet, it's one of the planet's highest volcanoes. But finding refuge at its feet is a very special little frog. This is the Quito Rocket frog. They were once common across the Ecuadorian Andes, but disease and climate change have pushed them to the edge of extinction.

Frog chirping

NARRATOR

The tiny male sends a high-pitched call out through the undergrowth. He's waiting for a response from a female. Unfortunately, there's no answer. And that's not too surprising, as there are only thought to be around 100 individuals left in the wild. Like other disappearing species of frogs, he's one of rarest animals in the world. Along with the rest of his kind, he now inhabits just one small creek. And if finding the last of his kind isn't hard enough, the volcano on which this frog lives has awakened. Cotopaxi's summit is home to one of the world's few equatorial glaciers. A catastrophic eruption here would create devastating lahars, boiling flash floods created by the rapid melting of snow and ice by the lava. If the volcano were to erupt, the stream that is home to this little frog would be transformed into a hot mudslide. Thankfully, the Rocket frog now has a helping hand from a team of scientists from Quito. Andres and his team are frog fanatics.

DR. MERINO

This is the last known location where this frog can be found. It's very difficult to find the frogs. The best way to do it is try to make them call to you back. So we make the sound...

whistling

DR. MERINO

And that's the sound of the mating call so they can respond to us.

NARRATOR

The team is now frantically collecting the last remaining individuals for a breeding program.

Whistling

NARRATOR

If successful, they will release a population back into a safer stream, out of the volcano's reach. For now, the fate of a species is in the hands of Andres and his team... and Cotopaxi. But back in Europe, some of the animals found around Mount Etna might have the upper hand when facing off with a giant volcano. The Argentata dell'Etna is a breed of goat found nowhere else in the world. Each morning, Gaitano herds his animals out onto the slopes of the volcano. The goats will eat just about anything. But Gaitano knows that on the upper slopes of Etna, there are glades of a yellow flower that he thinks gives his goats' milk a unique taste. Gaitano has been working on the mountain his whole life, and in that time, he's noticed some bizarre behavior in his animals. He believes that the goats behave erratically, not just during one of Etna's eruptions, but before one.

Goats bleating

NARRATOR

A team of scientists using GPS tags have now corroborated Gaitano's theory. The goats do, in fact, seem to be moving off the mountain before an eruption.

Bleating

NARRATOR

It's as if they have a sixth sense... an intimate connection to the Earth.

Bleating continues

NARRATOR

Could it be the vibration in the ground? Or the smell in the air? No one is sure what is triggering their retreat. But the next time you see a humble goat running in the opposite direction, it might pay to follow it. It's dawn in Vanuatu, and today, the weather is looking much more promising. In a few hours, Jeff will come face to face with the burning heart of Marum.

DR. MARLOW

I think anyone would be terrified going into this crater. My family would think I'm insane, my friends would question why this seems like a good thing to do. There's an easier way to do science. That may be true but the samples we're after are extremely rare. So yeah, it's nerve-racking, but taking these risks for the science makes a lot of sense to me.

HORSLEY

Okay. Ready to rock?

DR. MARLOW

Ready to rock.

Let's do this. -HORSLEY

Cool. Awesome.

NARRATOR

The pair's first challenge is the 1,300-foot vertical drop down to the crater floor.

HORSLEY

The fear and what's going on in the back of your mind there is a vertical cliff, a lava lake in the background, and so much lose material all around you that it's quite physically and mentally demanding. Right now you've got all your trust in a nylon rope. There's a lot of loose material there so we need to really careful on where we put our rope,

especially in these stages. -DR. MARLOW

Yup.

HORSLEY

This is our biggest concern now.

DR. MARLOW

Ready to do this?

HORSLEY

Let's do it.

DR. MARLOW

Okay.

HORSLEY

Okay, as soon as you get to this bottom section I want us to get out of this water course and move out of it as quick as possible. Okay?

DR. MARLOW

Yeah. This is the rock-fall zone.

HORSLEY

This is a rock-fall zone. Look at every stone and make sure it's a solid step.

NARRATOR

Once they clear the wall, they come face to face with the boulder field.

HORSLEY

And that's going to be a nightmare to cross. This unstable plateau of boulders. We're going to have to cut across here, and then head down. A tumble here could certainly mean a fiery death. As soon as we're on that black ash plain, I'm happy.

NARRATOR

Just as Jeff and Chris make it to the other side, there's bad news from the summit.

DR. KALLMEYER

Okay, just a little weather update, so it's still okay here but the clouds are definitely lowering so we might be in for quite a bit of rain pretty soon.

HORSLEY

Obviously it's extremely acidic down here. If it does rain, we want to get out of here as fast as possible.

NARRATOR

As the team approaches the lava lake in Vanuatu, in Hawaii, the eruption is beginning to slow down. The lava is starting to cool and harden. Despite the hostility of the landscape, it doesn't take too long for life to spring from the ashes.

Birds chirping

NARRATOR

The Ohia Lehua is among the first to flourish in this new land. It's a tree native to Hawaii and well adapted to living on the lava flows. It helps to break down the hard rock into soil that will support an entire ecosystem. It can take 200 years of struggle for life to reclaim what was once its own. Few animals managed to reach a speck of land this far out in the middle of the ocean. Those that did find a way have been free to evolve into new ecological niches created by the volcano.

Creatures chirping, calling

NARRATOR

This is certainly true of the island's insects. Nearly every species of caterpillar in the world is a herbivore, a plant eater. Every species except for But this caterpillar is not looking for a leaf to eat. His claws are better suited to a more, lively meal. A planthopper. The best way to catch its prey is to launch an ambush attack. To stand a chance, the caterpillar needs to find some better camouflage... And then wait for its prey to come close. Tiny sensitive clasps on the tip of its abdomen will trigger the attack. Hawaii is a land of strange and bizarre creatures. Isolated out in the Pacific, ninety percent of its native species are found nowhere else on the planet. And the continual disturbance by the volcano has created a landscape that can fast-track evolution. But it's not just the volcanic forests that harbor unique life forms. There is another hidden ecosystem within the volcano. A secret labyrinth carved by the flow of molten rock. These caves were created by underground rivers of lava that have since run dry. Annette Engel and Megan Porter are here to search for creatures that live in this underworld.

PORTER

The really amazing thing about lava tubes is that as soon as that lava has drained, and it's cooled, then there are spaces available for animals to live in.

NARRATOR

But the lava has left an obstacle course in its wake.

ENGEL

Well I think I know what's coming up. Ugh. I wish we didn't have to go through the squeeze.

PORTER

The lava, because it's so pointy, you're trying to crawl through a tube that is like a porcupine, it's got spines on it, so it's catching everything as you move.

NARRATOR

No sunlight delivers energy into these caves. For years, the scientists were unsure as to what could possibly be living down here. But thanks to a little help from the surface, there's an unusual and thriving ecosystem inside the volcano.

PORTER

The roots come down into lava tubes looking for water and then those roots also structure the subterranean communities.

NARRATOR

The roots are like a delivery system. They provide tiny amounts of sticky sap for life to live on.

PORTER

Ooo, I think I found something.

ENGEL

Oh yeah? What is it?

PORTER

Let's go ahead and collect it and see.

ENGEL

Yay!

PORTER

Excellent.

NARRATOR

Many of these creatures are descendants of surface animals that lost their way in the caves back through evolutionary time. Like this translucent thread-legged bug, a relative of the praying mantis.

PORTER

It's called thread-legged because it has very long thin spindly legs. It was first described from some caves on the other side of the island, which is pretty far from here, so we're pretty sure that this is a new species. I think there are so many new species in these sorts of environments because of the volcano, because it is just such an active system, it is both destroying and creating new habitat, that opens up space for species to move underground and to evolve and to become very distinct.

NARRATOR

This is a fragile ecosystem. It's entirely reliant on the ecosystem above for its support.

PORTER

If the volcano wiped out the forest above where we're standing, that's gonna wipe out the nutrient source for this ecosystem, because those root systems are really the life blood of the ecosystem down here. But what we see is that as the forest recovers eventually then you have insects that also move underground, and so it's a cycle.

NARRATOR

And today, the cycle of death and creation continues on in Hawaii. Nowhere on Earth have volcanoes affected the circle of life more than a few thousand miles to the east, in the Galapagos. This violent, volcanic outpost is home to an array of animals unique to these islands. The giant tortoise is one such creature. This individual shares the island of Isabella with the active vents of the Alcedo volcano. Tortoises are cold-blooded animals, meaning they rely on heat from their external environment to survive. Each year, they migrate up to the crater in search of new feeding grounds. Along the way, they pause and appear to bask in the warmth of the active vents. And they snack on small bits of volcanic rock rich in minerals and salts. Even in a landscape riddled with volcanoes, life manages to find a way to thrive. The team in Vanuatu has finally reached the edge of the lava lake. The world that meets them at the bottom is full of steaming fumaroles and toxic clouds. Some of the water here is as acidic as battery acid......but Jeff hopes that extreme microscopic life forms are hiding within the sediment. He also wants to collect rocks bathed in the radiant heat and sulphurous clouds of the lava lake itself. Getting close enough for that requires an extra level of protection.

DR. MARLOW

The lava lake itself has this magnetic pull. This extremely deadly feature makes you keenly aware of how alive you really are.

NARRATOR

Months of planning have led to this moment. Despite the dangers, Jeff pushes closer.

HORSLEY

Careful! Really, really careful. Watch out. Please, please, careful.

NARRATOR

If the rocks here harbor life, it could be in forms brand new to science. For Jeff, the samples are worth risking his life. Before leaving, he takes a temperature reading. The lava lake is off the scale, and the rock facing the heat is over 150 degrees. With the precious material bagged and labeled, Jeff and Chris begin the long journey back to camp... ...thankfully with some help from motorized ascenders.

HORSLEY

Okay.

Motors hum

DR. MARLOW

Life is found almost everywhere on Earth. But where is the line beyond which life can't go? What conditions are too much for even single-celled organisms, the bacteria and archaea, or maybe even types of life we've never seen before? By sampling here, we're seeking the very limits of what life can endure. We're alive! Made it! We're alive! Whoo!

NARRATOR

Discovering microscopic life forms in Marum could help the team reveal more about the extremes of life on Earth... and could even build a better picture of how life originated. Extreme conditions created by volcanoes are not limited to terrestrial environments. At the bottom of the ocean, where the Earth's tectonic plates part, the seafloor comes alive. Water and minerals, heated from volcanic activity beneath the surface, form giant hydrothermal vent systems. It's thought that it was in these kinds of environments that life began 3.7 billion years ago. The planet's first single-celled microbes needed an energy source. Harnessing the volcano, they burst into existence and ultimately evolved into the myriad life forms we see today.

DR. MARLOW

And it's that same process of producing a lot of energy and amazing gradients of heat, and that's what we see down here. That's what makes volcanoes really frightening in a lot of ways. They're very dangerous because of that but they also can provide that spark that life needs to begin.

Generator rumbles

NARRATOR

Back in camp, Jens and Jeff process the material taken from the crater floor, looking for signs of life from inside the volcano.

DR. MARLOW

We've stained some of our samples with a fluorescent dye that attaches to double-stranded DNA, the genetic material of life. If anything glows, that's a positive sign.

Gotcha. -DR. MARLOW

Yeah? You found stuff?

DR. KALLMEYER

Yep.

It's amazing. -DR. KALLMEYER

Yeah. Beautiful. Nice and shiny.

DR. MARLOW

That's amazing. There's life down there.

DR. KALLMEYER

Yep, we got a few cells.

NARRATOR

Jens can see luminous specs of light, a telltale sign of cells. The basic building blocks of life on Earth.

DR. MARLOW

That fact that life likely survives in the crater is amazing. These microbes can deal with conditions that you or I would think is instantly deadly, but to them it's home, and they've managed to eke out a living, getting just enough energy to survive. What that means in terms of life's origin and its possibility to exist on other planets, is still up for debate and we think that this is a really good place to start that quest.

NARRATOR

There are now many months of in-depth analysis ahead. The samples collected from the edge of the lava lake were photographed under a more advanced microscope back in the United States. Further study is still needed, but based on the team's observations, they're confident life lives within a few feet of one of the world's most active lava lakes. If we are to look for life among the stars, then we need to know what we are looking for. The discovery in Marum builds a picture of what life might look like elsewhere in our universe.

DR. MARLOW

This is the front lines of astrobiology and the idea of looking for life beyond Earth.

NARRATOR

Considering the fact that almost 30 volcanoes erupt every 24 hours, it's remarkable to think that life has not only managed to survive, it thrives on our violent planet. There's no doubt that life in the shadow of a volcano is full of risk. But is it time for us to re-align our perception of volcanoes? We're not here in spite of them. We are here because of them. To learn more about what you've seen on this "Nature" program, visit pbs.org.