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00:00A dense forest, leveled without explanation, ravenous insects on a path of total destruction, and a massive tremor that may
00:15have been caused by human hands.
00:19Fire, floods, earthquakes, humanity has always faced natural disasters that often strike without warning, leaving death and destruction in their
00:29wake.
00:30But there are many other strange and rare events that are just as frightening and deadly, like mysterious fireballs that
00:40race through the sky, exploding toxic lakes, and powerful tsunamis that, some believe, can summon the dead.
00:49Are these disasters simply freak events, or could they be signs of something unnatural at work?
00:58Well, that is what we'll try and find out.
01:15The Siberian Taiga, Russia.
01:18At over 2 million square miles, it's the largest forest on Earth.
01:24And on June 30th, 1908, this remote and inhospitable landscape experienced a devastating disaster known as the Tunguska Event.
01:37On this June morning in 1908, a massive explosion occurs over this remote part of Siberia.
01:46This became a major mystery in world history.
01:50At this period in time, this area was mostly inhabited by an indigenous group called the Ivenki.
01:57They had traditionally engaged in reindeer herding, and there were several of them who were out pretty close to the
02:05epicenter of the blast.
02:07The Ivenki herders see a bright object in the sky, described as brighter than the sun.
02:14And then they heard these loud booms, louder than gunshots.
02:21What the Ivenki described was nightmarish.
02:24Suddenly, another sun appears in the sky.
02:28They hear the loudest noise you've ever heard, along with a very violent shockwave.
02:34People were blasted off their feet and thrown a distance.
02:38And then, almost as fast as it started, this fades away.
02:44And you're left wondering, what happened?
02:47There is an enormous explosion.
02:51And what happens is that something like 80 million trees are flattened over an 800-square-mile area.
03:01I mean, this is absolutely bizarre.
03:04And yet, here you have this devastation.
03:07That must have been terrifying.
03:10Every single tree is flattened in the same direction.
03:1380 million of them over 800 square miles.
03:16We just see flattened trees, completely scorched and devoid of any branches or leaves.
03:22What kind of explosive force had the power to annihilate an 800-square-mile area?
03:29It's been estimated this would require the energy equivalent of 1,000 atomic bombs.
03:37Early 20th century theories proposed the disaster was the work of a massive meteor striking the Siberian wilderness.
03:47When the Tunguska blast occurred in 1908, and even when it was first investigated in the late 1920s,
03:54the expectation was that this must be one of the largest meteorite events in modern times.
04:00One of the early researchers was this guy, Linid Kulik, who gets support from the Soviet Academy of Sciences to
04:08begin these expeditions.
04:09In 1928, Linid Kulik expected to find a crater and a big chunk of metal.
04:19But he did not find a crater or a meteorite.
04:24Even to this day, we have not found a crater that was caused by Tunguska,
04:29or even material that can clearly be traced back to a cosmic origin in 1908.
04:37How does something smashing into Earth leave no crater and flatten 80 million trees without leaving any other trace of
04:44it?
04:44When an asteroid or comet smacks into Earth's surface, the classic thing that you get is an impact crater.
04:52Meteor Crater in Arizona is a perfect example of this.
04:54But in the Tunguska event, we see no evidence of a crater at all.
05:00And so the enigma here is, how do you get potentially something striking Earth, but not seemingly to strike Earth
05:06at all?
05:08In the absence of an impact crater or verified cosmic debris,
05:13attempts to explain the unnatural event have ranged from a black hole passing through Earth to weapons of mass destruction.
05:23But 70 years after Tunguska, a strange anomaly on a small island in Newfoundland, Canada,
05:31may offer some clues to the cause of the mysterious Siberian disaster.
05:37It's known as the Bell Island Boom.
05:41April 2nd, 1978, in Newfoundland, about 5,000 residents of Bell Island suddenly, spontaneously see an enormous flash of light.
05:52And it's followed by an explosion that damages almost every building in the town.
06:00Gouts of blue fire erupt from power outlets.
06:04Livestock were killed.
06:06And the sound of this blast was heard 80, 90 miles away.
06:11And initially they thought, well, maybe this was a giant meteor impact, but there was no crater.
06:16There was no impact debris.
06:17So people thought immediately of similarities with Tunguska.
06:22One possible explanation for the Bell Island Boom is what we call a Superbolt.
06:28We think that Superbolts are basically lightning bolts, but they're far, far more powerful than a normal one.
06:33They release trillions of watts of energy instantaneously.
06:37So that leads scientists to wonder, could a Superbolt be responsible for this Bell Island Boom?
06:43Was an extremely rare and powerful lightning strike the cause of both the Bell Island Boom and perhaps the Tunguska
06:53event?
06:54Well, it's a matter of speculation.
06:56And many scientists believe the real answer came even more recently and much closer to where the Tunguska event took
07:05place.
07:09Tchelyabinsk, Russia.
07:11This major industrial center near the border of the Siberian Taiga is one of the largest cities in Russia.
07:19On February 15, 2013, at approximately 9.20 a.m.,
07:25residents record incredible footage of a meteor the size of a house rocketing through the sky.
07:36Sometimes an asteroid or a comet can come in at a very shallow angle, parallel with the surface of the
07:42Earth, to blow up in the atmosphere.
07:45And it's there where you can get something we call an airburst.
07:49In 2013, there was just such an airburst.
07:54It was about 14 or 15 miles up.
07:57It came in, heated up, turned into a fireball brighter than the sun, and left a huge cloud through the
08:04atmosphere.
08:06And people filed outside to see what the bright light was caused by.
08:12And little did they know, that whole time, through the air, was an invisible shockwave carrying the sound and the
08:18force of that blast, half a megaton.
08:20And boom!
08:23Every window in the town is shattered, every car alarm goes off at the same time.
08:29Thousands of buildings were damaged, thousands of people injured, and this was a small-scale Tunguska that we got on
08:36video.
08:38We now think that the most likely explanation for the Tunguska event is that an object hit Earth's atmosphere at
08:46extremely high velocity and exploded.
08:48And that energy release was enough to flatten those trees, scorch the ones nearby.
08:53And rather than excavating a crater, it basically just blasts out a wave of energy that flattens trees.
09:00And it may be that the Chelyabinsk event explains all of the eyewitness testimony of people back in 1908 reporting
09:07what they saw.
09:08It's our best explanation right now, but we may never know for sure what caused the blast in 1908.
09:19East Africa, this dry and arid region encompassing Kenya, Ethiopia, and Somalia, is famous for its dramatic mountains and vast
09:32savannas.
09:32But in 2019, it became ground zero for a locust swarm of unimaginable proportions.
09:43The most famed or infamous locust is the desert locust of Africa.
09:48Where they land, it's utter devastation.
09:51They are descending in order to feed, and you can watch your fields disappear before your eyes.
09:59So, to understand locust swarm, you have to kind of go back a few months or a few years.
10:08The parents of these locusts would have appeared as garden-variety grasshoppers.
10:14But then the conditions change.
10:17It becomes drier.
10:18And they undergo a Dr. Jekyll to Mr. Hyde transmogrification.
10:23And instead of their offspring looking like their parents, they're like mobs of small, wingless locusts that march across the
10:34land, just eating whatever they encounter.
10:37And then, after about three weeks, they molt into adults, winged adults, and they rise into the sky.
10:43And they appear to be kind of a glittering storm cloud on the horizon.
10:50And if you're a farmer, you watch your crops melt in front of you, so it looks like a wildfire
10:57is swept through.
10:58Nothing is going to stop them until they're done.
11:01They leave nothing behind except misery and hunger.
11:07The East African locust swarm of 2019 destroyed an estimated $8.5 billion worth of crops, resulting in a food
11:16crisis affecting nearly 25 million people.
11:18But history's most devastating and mysterious swarm of locusts assembled nearly 150 years before the African disaster.
11:29This time, in the United States.
11:36The Great Plains, 1875.
11:41From the Rocky Mountains to the Mississippi River, American farmers struggle to survive.
11:49Years of harsh weather conditions and drought creates hard, dry prairie soil, difficult to farm.
11:57But even more devastating is the freakish mega swarm of Rocky Mountain locusts that have assembled on a biblical scale.
12:08This wasn't just any locust swarm.
12:10There were more than 12 trillion locusts that made a swath that was a thousand miles long.
12:19And basically, you can think of a swarm the size of California munching its way across the American Midwest.
12:26And these locusts were so ravenous, they not only absolutely annihilated all the crops in the American Midwest, the locusts
12:36began eating anything else they could find that was organic.
12:39That includes the wool off of live sheep.
12:44It includes wood structural elements of houses.
12:48And it includes clothing that people were wearing.
12:51And so this was terrifying. These things were alive and they were hungry.
12:57This mega swarm of 1875 is the largest recorded swarm in human history.
13:04It was 2,000 times larger than the next largest known swarm of locusts on planet Earth.
13:13Something that summer coalesced them into this mega swarm.
13:19It was a natural disaster of unimaginable scale.
13:23500 to 1,000 tons of vegetation have to be consumed every day to fuel that swarm.
13:31Much of the Midwest was going to face hunger.
13:33People are going to die.
13:36But we don't really know very much about what led up to it.
13:41Over the course of three years, the ravenous insects devoured $116 billion worth of crops and property, leading to widespread
13:51starvation and complete financial ruin for countless families.
13:55And based on this unfathomable devastation, many wondered, was this mysterious disaster a grim judgment from the Almighty?
14:07If you read the newspapers from the time, it really conveys the terror that these farming communities felt as these
14:16locusts completely destroyed their livelihoods.
14:19And of course, many of these God-fearing people looked to the Bible and thought, well, Pharaoh in Egypt was
14:27punished with locusts.
14:30Surely we're being punished for our sinfulness.
14:33We have done something wrong, and we are now facing divine retribution.
14:38That's what many people thought.
14:41Governors in five Western states declared days of prayer.
14:46And then you say, well, God helps those who help themselves.
14:51What do you do in the industrial age to fight nature?
14:58Build a machine, right?
15:00Machinery must be the answer.
15:03All kinds of machines are built.
15:05One was called the King Suction Machine, a belt-driven gigantic vacuum that would suck up the nymphs.
15:13These are the wingless immatures.
15:15And bag them.
15:17You might try various rolling devices to crush these locusts.
15:22One of my favorites was basically a flamethrower to torch the locusts.
15:29Not very effective, but it probably felt pretty good.
15:33Now, did it make a dent in the locusts? Probably not.
15:36But it did give the people a sense of being in control.
15:41Well, we still don't know what caused the largest, most destructive locust swarm in history.
15:46What's even more perplexing is that by the year 1902, just 27 years later, the Rocky Mountain locust completely vanished
15:57from the face of the earth.
16:00It was only a couple of decades after this titanic storm of locusts that the Rocky Mountain locust went extinct,
16:07disappeared forever.
16:09You talk about a dynamic contrast.
16:11It went from effectively swallowing the country to vanishing without a trace.
16:17And why?
16:19Well, perhaps it was loss of habitat and human civilization's advance just meant the conditions weren't favorable for them anymore.
16:26We don't really know.
16:28Another theory was they didn't go anywhere. They're still here.
16:32It just so happens that the right conditions have not happened again.
16:37That would transform an existing grasshopper into the Rocky Mountain locust.
16:42We still can't explain what caused the rise of the Rocky Mountain locust swarm and ultimately what caused their demise.
16:51And it may forever remain a mystery.
16:57It's baffling to think that trillions of locusts swarming over an area more than a thousand miles wide could suddenly
17:04vanish into extinction.
17:07But that's not the only mystery of nature that continues to defy scientific understanding.
17:13For example, there's a lake in Cameroon that may be part of a network of toxic ticking time bombs.
17:26Northwestern Cameroon, August 21st, 1986.
17:32The sun rises over the hills surrounding an ancient body of water known as Lake Nyos and reveals an apocalyptic
17:41scene.
17:43In nearby villages, lifeless bodies are strewn about as if a mysterious forest had swept across the land, killing nearly
17:53everything in its path.
17:55There was a terrifying geological catastrophe that occurred.
18:00Something disrupted this lake.
18:02Locals reported a rumbling sound and what might be described as an explosion.
18:09As the lake suddenly came to life and anyone who was caught in its path instantly dropped dead.
18:18The death toll was staggering.
18:21It's estimated around 1,700 people and 3,500 animals were killed across a 14 mile radius.
18:30With no obvious cause of death, an international team of scientists, including American biologist George Kling, was dispatched to investigate.
18:41We really didn't know what had happened, what had caused this.
18:46And the lake itself was very reddish orange, like a rust color that we really don't see very often in
18:58lakes.
18:58And there was a lot of damage around the shoreline from some large wave that must have been produced with
19:07enough force to wash away all the vegetation and soil down to bare rock.
19:11And lakes just don't explode like that.
19:14What exploded out of Lake Nyos, killing everything in its path?
19:20Given that the lake was formed in an ancient volcanic crater, investigators feared that an eruption deep underground released a
19:30surge of deadly gas.
19:32Many of the survivors reported smelling rotten eggs or gunpowder, and that's an unmistakable smell of sulfur.
19:40And they reported feeling warm.
19:43And we know volcanoes produce a lot of sulfur gas and a lot of heat.
19:48But when we started analyzing our samples, we found no sulfur in the lake water.
19:54We found no excess sulfur in the plants around the lake that had been exposed to this gas cloud.
20:02And when the army pathologists did autopsies, they found no evidence that people were poisoned by sulfur gas.
20:11No poisoning by sulfur gas?
20:15Experts were left wondering if the cause of this deadly disaster was even geological at all.
20:21Local rumors swirled about chemical spills, weapon tests, even stories about vengeful spirits in the lake.
20:31But George Kling found something intriguing buried in old medical reports.
20:39A clue pointing to a rather unlikely culprit.
20:43A gas that we all produce when we exhale.
20:47Carbon dioxide, otherwise known as CO2.
20:54We ran across some older medical literature that had used high concentrations of CO2 to test for oxygen stress in
21:03fighter pilots.
21:04And it turns out that CO2 above concentrations of about 6% acts as a sensory hallucinogen.
21:12And one of the most common reports from the fighter pilots was that they smelled rotten eggs and gunpowder and
21:18that they felt very warm.
21:20So we knew that this was a CO2 release.
21:25And we suspected that the gas was held in the lake.
21:29It turns out that the lake itself could hold a huge amount of gas in the bottom waters.
21:37Kling's tests reveal that Lake Nyos was primed for disaster.
21:42Over centuries, the lake had become a pressurized chamber of carbon dioxide.
21:48And when that chamber exploded, it released a massive wave of suffocating gas that raced across the land at over
21:5760 miles per hour.
22:00Lake Nyos, as it turns out, was supercharged in carbon dioxide, much like a soda can if you shook it
22:08up before you opened it.
22:11So anyone unfortunate to be caught in its path?
22:14Couldn't breathe.
22:16One of the things that made this event so deadly was that this CO2 gas cloud was enormous first off.
22:25But because it was heavier than air, it flowed out of the lake and down the river valleys very quickly.
22:32So even if people had seen the cloud coming, they couldn't have gotten out of the way.
22:36And people just essentially died in place.
22:41Lake Nyos was vulnerable to this kind of an event because it was formed by volcanic activity.
22:48And it's also very deep.
22:51So those deep waters could store a lot of gas.
22:55But once we have the gas build up, we have to have a trigger.
22:58And this could be any number of things.
23:00For example, it could be a landslide that caused the gas burst.
23:06But we'll probably never know for sure what triggered this disaster.
23:13Based on Clinton's discovery, Lake Nyos is now monitored around the clock to help anticipate another deadly gas event.
23:22But solving the Lake Nyos disaster reveals a far more terrifying question.
23:29With more lakes potentially primed for the same kind of catastrophe, when and where could this happen again?
23:40Lake Kivu in East Africa is the nasty big brother of Lake Nyos.
23:46It's 1,600 times larger.
23:48It has 1,000 times more gas in it.
23:51And because there are millions of people living around the shoreline of that lake,
23:55it's the largest ticking time bomb in the world.
23:59There are active volcanoes in the area.
24:02And these volcanoes could destabilize it and trigger a gas burst.
24:07We haven't looked at every single lake in the world.
24:09But we know now enough about what kinds of lakes could be dangerous.
24:16Knowing that this is a process that the Earth can throw at us, it's natural to wonder, are other lakes
24:21susceptible?
24:22The good news is, this doesn't happen everywhere.
24:24But the bad news is, if there's one that we don't know about, we need to find it first before
24:30it lets us know it's there in all the worst ways.
24:36How many lakes around the world are filled with poisonous gases that could explode at any minute?
24:42While there's much left to learn, there are some disasters that aren't triggered by natural processes that take millions of
24:49years to unleash.
24:50Like in the case of a catastrophic earthquake that may have been the result of human engineering.
25:02Throughout history, Mother Nature has revealed that the ground beneath our feet is far less stable than we like to
25:10imagine.
25:11In the last century alone, cities have been suddenly reduced to rubble.
25:17And nearly two million people around the world have been killed by the unbelievable ruin caused by earthquakes.
25:28Earthquakes we can observe around the world.
25:31Wherever you are on any continent, you have plenty of fault zones everywhere.
25:37Large fault zones will cause large earthquakes.
25:40And when an earthquake happens, if you build up stress over thousands and millions of years,
25:47and those fault zones can basically rupture at some point.
25:54While scientists can't predict when an earthquake will strike,
25:58we generally assume that they're caused by natural processes that take an extraordinarily long time.
26:05But could some of the deadliest earthquakes of the modern age be caused by human hands?
26:16Such one province, China, May 12, 2008.
26:21This region is home to over 80 million people,
26:25making it one of the most populous places in all of China.
26:29But just before 2.30 in the afternoon,
26:33a massive earthquake unleashes unspeakable death and destruction.
26:40On May 12, 2008, there was a 7.9 earthquake that occurred in Sichuan province in western China.
26:51And about 69,000 people died.
26:55Maybe 18,000 were missing that were presumably dead.
27:01And sometimes, probably 10% of the population perished.
27:05The economic damage is also huge.
27:10Around 130 billion U.S. dollars.
27:14And a lot of the damage was caused by landslides in the region.
27:18So the destruction and devastation caused in the region is immense.
27:26The deadly earthquake struck along a 155-mile fault line,
27:31running the base of the Longman Mountains.
27:33But when scientists pinpointed the quake's epicenter,
27:37they found something massive and man-made.
27:42The question is, what triggered that earthquake?
27:45Although we know that this region is a natural seismic region,
27:49where we have earthquakes every other hundreds of years,
27:53seismologists are able to measure how waves propagate through the Earth crust.
27:57And that's what they did.
27:59They looked at the seismic wave, they recorded,
28:02and they could see that in the first 10 to 15 seconds,
28:07most of the energy was released right in the vicinity of the Zipping Poo Dam.
28:13The Zipping Poo Dam stands over 500 feet tall,
28:18and its reservoir holds more than 296 billion gallons of water,
28:23weighing more than one trillion tons.
28:28Scientists began to wonder,
28:30did this monumental engineering project somehow trigger the earthquake
28:35that killed an estimated 87,000 people?
28:39When it comes to the idea of humans artificially triggering earthquakes to occur,
28:45if you do something to add a lot of weight to an area,
28:48like create a dam and then generate a new lake,
28:53well, the weight of all of that water can induce any number of changes,
28:57and in some areas definitely activate earthquakes.
29:01At the Zipping Poo Reservoir,
29:03it's a lot of water and it's a lot of weight as well.
29:07And then the other indicator is about the distance.
29:11The epicenter location and the reservoir location
29:14is really uncomfortably close to each other, about six miles.
29:20So they also indicate there may be a link.
29:24Some suggested reservoir-induced earthquakes cannot be that large,
29:31but my quick response would be, why not?
29:34We calculated how much stress, how much pressure the Zipping Poo Reservoir
29:40has placed onto the fault over a period of several years.
29:46That's what led us to suggest that the pressure can be that large,
29:53and that could weaken the fault and trigger the earthquake.
30:00While it seems the Zipping Poo Reservoir could have a role in the deadly Sichuan earthquake,
30:06the theory remains controversial and is not acknowledged by the Chinese government.
30:12But it all raises a chilling question.
30:16What other massive man-made structures could potentially bring about an unnatural disaster?
30:25Closer to home, the Hoover Dam is among the largest reservoirs in the world.
30:31And in fact, even during its construction in the 1930s, there were quakes nearby
30:36because there are structures in the ground that are going to move.
30:40The big question becomes this.
30:42If those structures move again, are we going to have an issue with this dam?
30:50There's no doubt that whether it's caused by man or Mother Nature, those impacted by a disaster are left haunted
30:58by the event itself and the aftermath that follows.
31:02But when the tsunami of 2011 destroyed parts of Japan, some locals were affected on an otherworldly level, when the
31:12living were reportedly visited by the dead.
31:20Japan, March the 11th, 2011, 2.46 PM.
31:26A massive 9.1 magnitude earthquake strikes dangerously close to the Japanese mainland.
31:33This seismic event displaces so much water, it sends 100-foot waves barreling towards Japan's eastern shore at 500 miles
31:44per hour.
31:46In an event known as the Tohoku earthquake and tsunami.
31:52The earthquake set off a massive tsunami, which struck the coastline of eastern Japan, and that is what caused devastating
32:01damage.
32:02It's like the tide coming in unstoppably, massively, and very, very, very fast.
32:09The tsunami smashed into villages, towns, ports, all along the coast.
32:16It caused a meltdown at the Fukushima Daiichi Nuclear Power Station, which turned into the second worst nuclear disaster in
32:25history.
32:26The devastation is overwhelming.
32:30Imagine turning all houses, factories sideways, spreading out all the chemicals and debris, destroying roads.
32:39You have flows that are filled not just with mud and trees, but cars and building fragments and rooftops.
32:44And this is spread all the way inland, many miles, and then dragged back out to sea.
32:52There were more than 19,000 people killed in this event, and it becomes the deadliest event in Japan's history
32:59since World War II.
33:00The entire region grappled with enormous loss and unimaginable trauma.
33:07And some who managed to escape death would also experience disturbing events of an otherworldly kind.
33:16Because in the months after the tragedy, tsunami survivors started to report ghostly encounters with the dead.
33:25Six months or so after the tsunami, among many people who survived it, you did begin to hear various stories
33:34about supernatural mysterious events.
33:38There were stories about mysterious figures glimpsed by the coast on the beach.
33:46And then there were also the stories told by taxi drivers.
33:52A taxi driver is flagged down by a lonely figure who got in the back of the taxi and gave
34:00him an address.
34:01And he gets there, and sure enough, there is nothing there.
34:04All the houses have been smashed to pieces by the wave.
34:07When he looks in the back of the taxi, the person isn't there.
34:11And he understands that the passenger was a ghost who wanted to go back to the place where they'd formerly
34:18lived.
34:19There was something ghostly happening along that stricken coast.
34:27Did thousands of sudden deaths unleash the spirits of those that perished in the tsunami?
34:34It's an unnerving question.
34:37Because there were also reports that these spirits possessed the living.
34:45I performed purification rituals, but also exorcism, if you will.
34:51Living people were possessed by spirits.
34:55After the tsunami, everyone around there had almost no physical or mental immunity left.
35:01So they were in a state where spirits could easily attach themselves.
35:05So our method of exorcism involved guiding them into a meditative state.
35:09And then expelling it with a big breath.
35:12Strangely enough, with one woman, smoke suddenly puffed out of her mouth and the spirit left her.
35:18And when she came back to normal, she was like, why am I here?
35:22Did something happen to me?
35:26While the actual number of claimed spirit possessions is unknown,
35:30mediums, folk healers, and holy men became inundated with desperate calls for help.
35:39I was in the thick of it, facing people suffering from possession and doing whatever I could.
35:46They're in a daze, their faces blank, they're limp.
35:51It feels like their personality has changed.
35:54We performed rites to calm them.
35:59You need the power of ritual and the power of deep listening.
36:05I engage with them and release them from possession and brought them back to daily life.
36:13But facing possession takes so much out of you, to the point you feel you might die.
36:21Did tsunami ghosts roam Japan's devastated coast and possess those that survived?
36:30While some are convinced that this was a real supernatural phenomenon,
36:34others suggest a less esoteric explanation.
36:39After a terrible disaster like this, I think there are two impulses that people have.
36:45One is naturally to feel horror about what has happened.
36:49And I think these stories of ghosts, the sense of the supernatural bearing in on all sides,
36:55is an aspect of that, of that fear and that horror.
36:58But there was another side to it.
37:00There's a strong, strong yearning to connect with the dead.
37:05To say the goodbyes, the farewells that weren't possible in this sudden catastrophe.
37:11But to the people having the experiences, they were very, very real.
37:15And they needed to be taken seriously.
37:25Natural disasters have always threatened humanity.
37:29Some believe the danger is only growing.
37:32During the year 2000 and 2019, there were over 7,000 major recorded disaster events around the world.
37:42Nearly twice as many than the previous two decades.
37:47And scientists swore that the next major disaster could come from immense forces buried beneath the Earth's crust.
37:57One source of catastrophic environmental change we know happened in Earth's history are gigantic volcanic eruptions.
38:05If we look through the geological record, we see thousands of these events, like we saw in Siberia about 250
38:12million years ago.
38:14Leading to the biggest mass extinction in Earth's history.
38:1898% of all species on Earth went extinct.
38:22The atmosphere was rendered almost unbreathable because of how much CO2 came out.
38:27We know that these kinds of events have happened through Earth's history.
38:30In fact, geologically, they happen regularly.
38:33And we do not have the ability to predict if or when the next one will happen.
38:39There are catastrophic eruptions that volcanoes are capable of.
38:43And Yellowstone is a great example.
38:46Yellowstone Caldera is a huge depression in the ground with an enormous body of magma at depth.
38:51Now right now, that magma seems to be relatively stable.
38:55But we know that there were gigantic volcanic eruptions in the past and it may yet explode in the future.
39:02Could a massive volcanic eruption unleash Earth's next mass extinction event?
39:08It has happened before.
39:11But there are other apocalyptic forces not born of this Earth.
39:15Like the same cosmic threat believed to have killed the dinosaurs.
39:21A lot of extinctions in our past were actually caused by comets.
39:25If you were to look at our solar system, the whole solar system is surrounded by a giant sphere of
39:32old junk.
39:34Think of it as icy spare parts from when the solar system was first built.
39:39This is where all comets come from.
39:42And one hypothesis is that as our solar system moves through the galaxy, bam!
39:50A slew of comets are fired in toward the inner solar system, and so it really does make you wonder
39:56whether due to mass extinctions have to do with our galactic neighborhood.
40:01Will a series of comets soon bombard Earth like artillery shells?
40:07The fact is we can't accurately predict future disasters at all.
40:12And mankind lives and dies at the mercy of forces that are beyond our control.
40:21At some point in the future, it won't be a question of if, but when, Earth decides to clean house.
40:29But every time these disasters happen, the environment bounces back.
40:33Now I hope we won't learn this in our own lifetimes, but it will surely happen again at some point.
40:39One question we should ask is, have we figured out all the ways in which these disasters might happen?
40:46Most of us understand that being prepared doesn't always help us when we're exposed to the unknown.
40:51We have to accumulate more facts, more information.
40:55Sometimes people assume that scientists have it all figured out, that they have seen everything, they pretty much understand what's
41:03happening.
41:04But these disasters have really shown us that we had no idea about major events that have happened in the
41:15past and may happen in the future as well.
41:19Is Earth overdue for an unspeakable disaster on a scale we've never witnessed before?
41:26Well, I sure hope not.
41:29And whether a massive volcano erupts, a giant space rock collides with Earth, or any number of terrible cataclysms are
41:39on the horizon,
41:40and it's clear that deadly catastrophes are inevitable as long as we call this planet our home.
41:46While Mother Nature has taught us to respect the elements, it's the unpredictable and unnatural disasters that leave us humbled
41:55by forces that remain unexplained.
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