[music playing] JV MARTIN: A respected scientist
believes an oceanic catastrophe threatens Earth. A massive release of
volatile methane gas. GREGORY RYSKIN: The damage will
be of a scale which has not been observed ever. JV MARTIN: A methane eruption
may have caused the greatest mass extinction in
Earth's history. If it occurred in the past,
it could strike once more in the future. GREGORY RYSKIN: There is
no question in my mind that it will happen again. JV MARTIN: Tsunamis inundate
coastal cities, and lightning ignites clouds of explosive gas. GREGORY RYSKIN: There will be
huge fires, conflagrations, explosions. JV MARTIN: Methane explosion
on "Mega Disasters." It's often called
the Big Blue Marble. Planet Earth, sheathed in its
cloak of life-giving water. But hidden at the
bottom of its oceans, there could be a
ticking time bomb. It is a vast reservoir of
potentially dangerous methane gas. In the deep ocean, huge
quantities of methane are held in solution
with the liquid seawater or frozen in ice deposits
trapped in sediment. Normally when methane
bubbles up from the seafloor, most of the bubbles
gradually disappear, because methane has the
ability to dissolve into water. No different than salt or
sugar, when it dissolves, it becomes invisible. Methane, the simplest
of all hydrocarbons, is the main component
of natural gas. It is both a resource
and a hazard. Dissolved in water,
it will not burn, but when it is
released into the air, any spark can make it explode. This is what can happen
when methane is ignited. The source of this
1994 explosion was an ordinary 36-inch
natural gas pipeline in Durham Woods, New Jersey. It created a blow torch of
1,500-degree flame 600 feet high for two and a half hours
until utility workers were finally able to shut
off the gas flow. As spectacular as
this seems, the amount of gas that caused
it is minuscule compared to the explosive
potential from methane in the ocean. GREGORY RYSKIN: The total
amount of natural gas, which is essentially methane, which
was released in that fireball is about 3 billion times less
than the amount which would be released in a reasonable
sized oceanic eruption. JV MARTIN: Dr. Gregory
Ryskin is a professor of chemical engineering at
Northwestern University. He has developed a
controversial theory that says the oceans can and
have produced methane eruptions on a global scale. GREGORY RYSKIN: It has
happened periodically over the last half-billion
years without fail. So there is no question in my
mind that it will happen again. JV MARTIN: Ryskin believes
that the worst methane eruption in Earth's history happened
250 million years ago, at the end of a time geologists
now call the Permian period. Methane, says Ryskin,
was responsible for the Permian mass extinction,
the largest mass extinction of all time. BOB BAKKER: What is
a mass extinction? Some people say, it's
just when a lot of species go extinct suddenly-- a lot. True, but that's not enough. Not only species, but groups
of species, whole categories of species. JV MARTIN: In the Permian
mass extinction, up to 95% of all species disappeared
from the face of the Earth. Today, many scientists
call it the Great Dying, and they continue
to debate its cause. BOB BAKKER: The terminal
Permian extinction has bothered us
paleontologists for 200 years. JV MARTIN: In the
past, researchers have theorized that the
extinction was caused by an ice age or climate change due to
movement of the continents, perhaps an asteroid strike,
a nearby supernova in space, or widespread volcanic
lava flows in Siberia. But Professor Ryskin believes
the extinction was the product of a giant methane eruption and
its incredible explosive force. GREGORY RYSKIN: The
amount of final energy which would be released then
the combustion and explosion of the methane in
a large eruption would be about
10,000 times greater than the total nuclear
stockpile which is available at this moment. JV MARTIN: Before the
Permian extinction, the Earth was a very
different-looking planet than it is today. Most of the
ever-drifting continents were fused together in one
giant landmass called Pangea. Before the dinosaurs,
tiger-sized finback reptiles lived among the primitive trees
while crocodile-like amphibians inhabited the swamps. An enormous planet-wide ocean
was populated by ancient fish, corals, and other sea creatures. Species that would disappear
between the end of the Permian and the beginning of
the Triassic period. GREGORY RYSKIN: In that times
of Permian-Triassic boundary, the situation, the
geographical situation was especially conducive
to the stagnant ocean. JV MARTIN: A stagnant basin in
the lowest part of the ocean is one of the first ingredients
in generating methane eruptions. Ryskin's theory
works like this-- deep pockets in the ocean allow
methane to accumulate over long periods of time. GREGORY RYSKIN: Perhaps hundreds
thousands of years, perhaps even millions of years. Until eventually the water
will be essentially saturated, it is dissolved methane. JV MARTIN: Methane itself comes
from the seabed where microbes dine on organic matter,
producing methane as a byproduct. In most parts of
the ocean, currents keep things moving,
helping to provide oxygen for other microbes that
consume methane, which keeps it from building up. GREGORY RYSKIN: Most
of the deep ocean is sort of ventilated--
in other words, it's very sluggishly
moving, but it is moving. JV MARTIN: But where there is no
motion, the ocean is stagnant, and the waters become
anoxic, meaning they have little oxygen, so no
methane-eating microbes can live there,
and the gas slowly dissolves into the deep waters. It's well-known that deep
water creates high pressure, and the more water is
under pressure, the more gas it can hold in solution. The pressure of the
deep stagnant basins on ancient earth may have
set the stage for the methane eruption. GREGORY RYSKIN:
The concentrations, the actual amount of methane
molecules in a given volume of water can be 200 times
greater near the seafloor than near the
surface of the ocean. JV MARTIN: In the
Permian period, a seafloor basin of
methane-saturated water may have reached
a breaking point. An earthquake, underwater
landslide, or even a meteor impact could
have been the trigger. And suddenly, like shaking
a gigantic soda bottle, the deepest part
of the ocean would have exploded in a deadly
storm of methane bubbles. The threat to life began
below the sea surface where the methane bubbles
pushed huge quantities of oxygen or water upward. The effect was to suffocate
marine animals on a wide scale. Then the churning
methane gushed skyward, shooting huge fountains
of gas-laden water into the air, a violent process
that may have gone on for days or weeks. Methane is lighter than air
and would normally float away, but in the chaos of
an ocean eruption, the swirling clouds
of gas and water stay low to the Earth's surface. GREGORY RYSKIN: The
expelled methane will be mixed to
these water droplets, and it's very important that it
will be heavier than the air, so it will be hiding in
the Earth as it spreads. Now this explosive
material is going to be ignited by lightning, and
then there will be huge fires, conflagrations, explosions. JV MARTIN: The shock of
the ocean's eruptions also may have sent tsunamis crashing
against Pangea's coasts, drowning animals that
lived on the shorelines. It would take the barren
Earth 5 million years to regain the diversity of life
it lost during the Great Dying. The mass extinction
is an accepted fact, but the notion of a methane
eruption as its cause is a radical idea
with little acceptance in the scientific community. Much of the skepticism
over Ryskin's theory stems from the fact that no one
has ever witnessed a methane eruption. Until recently, no one
imagined that any kind of gas had the potential to generate
such natural eruptions in water. But that changed in 1986
when a mountain lake in the African
nation of Cameroon erupted in a deadly carbon
dioxide gas explosion that was totally new to
human experience. GEORGE KLING: We
don't think of lakes as just rearing up and killing
massive amounts of people. And so this was a
very rare phenomenon. JV MARTIN: The concept of gas
exploding from bodies of water was suddenly plausible. If gas can create a
killer lake, then why not methane in a killer ocean? The idea of a violent
methane eruption from one of the world's oceans
seemed like science fiction until something very much
like it actually happened. It took place at Lake Nyos in
the African nation of Cameroon. GEORGE KLING: Well in 1986 in
Lake Nyos, something happened in lakes that had
never happened before. There was a tremendous
eruption of CO2 gas that was stored in the late. JV MARTIN: A huge fountain
driven by 1.6 million tons of carbon dioxide shot out
from the waters of Lake Nyos. GEORGE KLING: This gas, when
it came out of the lake, produced so much energy that it
generated a gas water fountain out of the lake that was
about 100 meters high. And it filled up the lake basin
because CO2 is about twice as heavy as air. It flowed out over the
spillway and coursed down through the river valleys where
it killed people up to 16 miles away from the lake. JV MARTIN: 1,700 local villagers
and all their livestock died, smothered by carbon
dioxide, which reached concentrations of nearly 100%. GEORGE KLING: In the
atmosphere, carbon dioxide is in a concentration
of about 0.03%-- so 1/300 of a percent. Now for humans, concentrations
aren't dangerous until they get to
about 10% or 15%. And at that point, they
produce an epiglottal stoppage. So your air pipe shuts
down very quickly, and actually, you die
from suffocation quickly. JV MARTIN: History is filled
with stories of volcanoes, earthquakes, and tsunamis,
but no one had ever recorded anything like the
gas explosion at Lake Nyos. GEORGE KLING: Part of
why it seemed impossible for this to happen--
this kind of an eruption to happen in a lake was that
it hadn't happened before. JV MARTIN: At Lake
Nyos, scientists discovered that far
below the lake floor, a pocket of hot magma generates
carbon dioxide gas that rises up into the lake bottom where
it continually dissolves in the water. The gas is stored in the
high pressure deep water. But if the pressure
is ever released, the gas bubbles out, exactly the
same principle as in a bottle of champagne. GEORGE KLING: In any bottle
with dissolved gas in it, like champagne, you
don't see the gas because the pressure
of the cap is forcing the gas into solution. However, when you take the
pressure off of the gas, and as you take the lid
off here, then what happens is the gas is free
to expand rapidly and it produces this
tremendous explosion. And you get the gas
coming out of solution with a lot of expansion force. JV MARTIN: In Lake Nyos,
the weight of the water acted like the champagne
cork, and a sudden disturbance released it. Kling and others believe
a landslide may have been the trigger, but it was the gas
itself that created the threat. GEORGE KLING: What happened at
Lake Nyos is that there were high concentrations of
gas in the bottom water-- CO2 that had built up over
very long periods of time. And nobody really knew about it. We didn't know that
it was so dangerous. JV MARTIN: Dangerous gas
under pressure in deep water was a rare phenomena, but
could it exist elsewhere? Apart from Nyos,
researchers found that gas is also accumulating in
African Lakes Monoun and Kivu. The discovery led scientists
to wonder whether this could happen again. The eruption at
Lake Nyos really lit a fuse in the scientific
community for an explosion of ideas about where else this
might have occurred, and most specifically, whether there were
these kinds of tremendous gas eruptions from the ocean. JV MARTIN: But this idea
that similar methane deposits in the ocean can cause
catastrophic eruptions is yet to be accepted by
mainstream scientists. GREGORY RYSKIN:
Well, at this moment, my theory is not
very popular, which is completely understandable,
because of its kind of radical nature. JV MARTIN: As a chemical
engineer studying subjects normally in the realm of
geologists and paleontologists, Professor Ryskin faces a
struggle for acceptance. MATTHEW HURTGEN:
The work is not what I would say the
most well-recognized or welcomed in the community. I can't say that too many
people are citing this work and considering it credible. GREGORY RYSKIN: Science
has become so wide nowadays that there is nobody
in the world who can understand all aspects of it. Now when an outsider
like me tries to sort of encroach on their
turf, people react differently. JV MARTIN: One objection
to Ryskin's theory is that the open ocean can't
keep methane bottled up enough to reach explosive proportions. You can't build up a lot
of methane in the water because eventually you
have so much methane that it can diffuse up. It can leak out
before it ever gets too high in the deep waters. JV MARTIN: Ryskin believes
methane production at ocean bottom
outpaces diffusion in deep, still waters. But another problem is the
need for a large ocean region stagnant enough to allow
methane to build up over time. GEORGE KLING: Most people
think that the oceans-- that the overall ocean,
the majority of the ocean would never become
that stagnant. JV MARTIN: Professor
Ryskin, however, is steadfast in his belief. GREGORY RYSKIN: I
have almost no doubt that there is a stagnant
basin somewhere where methane is accumulating as we speak. I have no idea where it might
be simply because the deep ocean is very little known. JV MARTIN: Another reason
some scientists disagree with Ryskin's theory is that
its destructive firestorms come from methane clouds that
stay low to the surface, but methane ordinarily floats
away into the upper atmosphere. At the University of
Michigan's Hydrodynamics Lab, Professor George
Kling demonstrates the basic principles. He pumps methane into soap
bubbles which rise quickly, and then burn when
touched by flame. But these bubbles rise because
they contain pure methane. GEORGE KLING: If you take pure
methane, it's lighter than air, so it will rise, just like
pure CO2 is heavier than air and it and it will sink. JV MARTIN: But in
an ocean eruption, gas is mixed with
microscopic water droplets. Scientists call it
a two-phase mixture. And when methane is
mixed with water, it behaves differently
than pure methane. GEORGE KLING: Once
the methane comes out, if it's truly pure methane
with no impurities in it, it will start to rise. However, this gas water
mixture increases the density of the methane to the point
that it won't simply flow away like a hot air balloon. Chances are it will be
ignited fairly quickly in the atmosphere, and so you
won't have to worry about it dissipating too much. JV MARTIN: But a
fiery gas explosion is not the only hazard we could
face from methane in the ocean. Methane is also hidden away in
a mysterious material called hydrate. Part water, part gas, it
looks like ice, but it burns. It holds more methane
in the world's oceans than anyone ever imagined,
and if it is ever released, it could turn the planet
into a searing hothouse. Methane bubbles up from the
ocean floor in many places around the world. Sites where plumes
of gas bubbles appear are called methane seeps. GREGORY RYSKIN: This plumes
may reach heights of hundreds of meters, but then they
disappear because methane gradually dissolves in water. JV MARTIN: In some
cases, the gas comes from the
sedimentary microbes that professor
Gregory Ryskin says may slowly generate enough
gas for an oceanic eruption. In other cases, the methane
comes from underground deposits associated with petroleum. This is the natural gas used for
heating homes and cooking food. We usually have to drill deep
into the earth to get it, but it sometimes leaks
out from small cracks in the ocean floor. IRA LEIFER: So we're going
to head to Trilogy seep which is due south of Coal Oil Point. JV MARTIN: Dr. Ira Leifer
studies methane seeps for the marine science
institute at the University of California, Santa Barbara. He is examining how much methane
released from the seafloor stays dissolved
in the ocean water and how much bubbles
to the surface to be released into the air. IRA LEIFER: These bubbles
saturate the water, kind of like your Coca-Cola, and the
methane can't go into the water anymore after a while because
there's so much methane in the water. JV MARTIN: Here, the shallow
waters and active currents allow the methane to bubble
out instead of being trapped under pressure. IRA LEIFER: Methane's buoyant,
so it rises very rapidly. And right now, there
are, one could say, an invisible smokestack of
methane that's rising up into the sky above us. JV MARTIN: As his boat
floats over the seep, Leifer keeps a careful watch
on just how concentrated the methane around him is. We're measuring about 4 PPM-- 4 parts per million
methane in the air around here, which is
about twice background, because there's a lot of
seepage, but pretty low. Now we're over an area
with large bubbles. We're up to 6 and 7, up to 10. OK, up to 20, 30,
50, up to 55 PPM. JV MARTIN: In just
minutes, the measurement jumps from 55 parts per million
to 5,000 parts per million. Still, there would have
to be eight times more for the flammable
gas to pose a danger. IRA LEIFER: One reaches
the lower explosive level for methane at 4%, which is
40,000 PPM, parts per million. In the plume that we've been
looking at today right here, the methane levels are not
high enough to be ignited; however, when puffs
of methane comes up, we do reach the lower
explosive level. In such a situation, if
you're smoking a cigarette, you'd be OK, but don't
light another one. JV MARTIN: Bubbling
seeps of methane gas may also come from
an unusual material called methane hydrate,
a little-known substance that forms in ocean depths
below 500 meters, which is 1,600 feet. IRA LEIFER: Methane hydrate
is a frozen form of ice in which methane gas is
trapped in the ice matrix. JV MARTIN: Hydrate starts
with methane gas dissolved in seawater. When the water freezes,
it creates a rigid cage of ice molecules around
each methane molecule. The process takes place
only at the low temperature and high pressure
of the deep oceans. The result looks a
lot like normal ice, but if you put a
flame to it, it burns. Hydrate could be
an immense source of natural gas for the future. Natural gas is normally pumped
out of pockets deep underground and the supply is limited. But vast deposits
of methane hydrates are buried in coastal
ocean sediments. The amount of methane
trapped in hydrates may be far more than is
known to exist in the ground. IRA LEIFER: It's estimated
that the total methane available in the ground in the
United States at the rate we're using it is about
a 70-year supply. If we could harness all of
the methane and hydrates in the continental US waters, we
would have a 3,000-year supply of methane. It's a vast quantity of methane,
so this is of great interest. This is also a great concern,
because we must be careful that in the process
of extracting this methane for use, we
don't accidentally release it into the environment and create
a catastrophe larger than we're trying to prevent. JV MARTIN: The existence of
methane hydrate in the world's oceans is another reason why
Professor Ryskin's eruption theory is unpopular
with other scientists. Here's why. Down to 500 meters below
the ocean's surface, methane dissolves
in water, but not in concentrations enough to
erupt in violent gas fountains as the theory predicts. But below the 500-meter
level, something happens. The methane no longer
dissolves in the water, but turns into solid
hydrate instead. For an eruption
to happen, methane has to be dissolved in water,
like CO2 in the champagne bottle. If the methane turns
to hydrate instead, it stays locked
up in its ice cage and an eruption may
not be possible. GERALD DICKENS: We cannot get
too much methane into the water before we precipitate
hydrate, the solid phase. It's very, very difficult to
conceive a notion where we have super saturated
conditions in the water because we can't do
that today in the lab or in the modern ocean. JV MARTIN: Hydrates form
at the low temperature and high pressure
of the deep ocean according to the laws
of thermodynamics, but Professor Ryskin believes
there is more to the story. GREGORY RYSKIN: Thermodynamics
is a very tricky science. Thermodynamics does not tell
us how long it might take for the dissolved methane
in the ocean water to precipitate as
methane hydrate. And according to
some calculations, it will take longer than
the age of the Earth. JV MARTIN: Although hydrates
float just like regular ice, they typically stay deep under
water trapped in seafloor sediments where they lock up
much of the ocean's methane. But an earthquake or
underwater landslide could release the hydrates,
and if that happens, methane can escape in
massive quantities. IRA LEIFER: And if you don't
maintain them at high pressure and low temperature,
they suddenly turn into gas,
potentially explosively. JV MARTIN: Gas escaping
from methane hydrates may look something like this. The molecular ice cage breaks
down, releasing pure methane gas into the water. If large amounts
of methane hydrate are shaken loose
from their sediments, gas could escape in
dangerous amounts. YOUXUE ZHANG: If a
large land is released and that dissociated
at the 500-meter level, then that part of the water
containing a lot of gas would be able to erupt similar
to our lake eruption process. JV MARTIN: Even if
the process is not a series of violent fountains as
in Lake Nyos or Ryskin's ocean eruption, large volumes of
methane suddenly released into the atmosphere
pose a different danger. A catastrophic methane
release from ocean hydrates could kick global
warming into overdrive. IRA LEIFER: Methane is a
very potent greenhouse gas. In fact, it's 25
times more potent than CO2 on a
molecule-by-molecule basis. JV MARTIN: As a greenhouse gas,
methane can make temperatures go up on a worldwide basis. In fact, there is now
evidence that methane may have caused the worst
planetary heat wave in Earth's history. FRANCESCA SMITH: There
was extreme warming and it was global. JV MARTIN: It wasn't
the mass extinction 250 million years in the past. Instead, it was far more recent. 55 million years ago, a
massive methane release kicked up the
Earth's temperature. The sudden change in climate
turned evolution on its head and set the stage for
the arrival of mankind. In 2001, NASA scientists
used computer simulations of Earth's ancient past to
look at the role of methane as a greenhouse gas in changing
the prehistoric climate. They suggested that movement
of Earth's tectonic plates caused a large-scale release of
methane from the ocean floor. Unlike the sudden disaster
that may have caused the Permian mass extinction
250 million years ago, methane may have been released
over hundreds or a few thousand years and caused global
temperatures to skyrocket. It took place 10 million
years after the disappearance of the dinosaurs as the
Paleocene epoch was ending and the Eocene was beginning. It was a time of sudden
climate change now called the Paleocene-Eocene
Thermal Maximum or PETM. FRANCESCA SMITH: The PETM is
a period of extreme and abrupt global warming that happened
about 55 million years ago where the Earth warmed by about
10 degrees Fahrenheit at least in a period of only
about 10,000 years. So that's geologically
very rapid. JV MARTIN: The methane that
caused the temperature spike disappeared long ago, but
scientists believe it was there because it left behind
evidence in the form of carbon. Besides four atoms of
hydrogen, each methane molecule has at its center a
single atom of carbon. In methane, the central atom
is carbon-12, which scientists call light carbon. But that element has another
stable form called carbon-13, also known as heavy carbon. When paleontologists examine
the ancient sediments from the PETM, they found
much more light carbon than the environment
normally has. The increase in light
carbon, they suspect, came from methane. MATTHEW HURTGEN: Methane is
drawing increasing amounts of interest lately because it
contains very light carbon, and when people
look at sediments, they find this light
carbon signature. GERALD DICKENS: The
simplest interpretation is enormous amount of carbon
that was enriched in 12-carbon, entered the ocean
and atmosphere. The explanation I favor is
that it's methane coming out of the bottom of the ocean. It's this large
reservoir of carbon that is sensitive to pressure
and temperature changes. JV MARTIN: The large
reservoir of methane was locked up in the frozen
methane hydrates that were buried in the seafloor,
just as they are today. But just what happened to
unlock them is uncertain. This is what the world
looked like at the juncture of the Paleocene
and Eocene epochs. The continents look familiar,
but Earth's tectonic plates had them on the move. India, for instance,
was in the process of smashing into Asia to
form the Himalayan Mountains. The ocean floor was
uplifted in these movements, and this is what the
NASA scientists suggest may have shaken loose methane
hydrates releasing methane as gas. PHILIP GINGERICH:
Sometimes these changes trigger either
uplift of big areas or especially trigger
changes in ocean circulation, and either one would warm and
destabilize seabed methane. JV MARTIN: The methane
would have bubbled out of the hydrates and reached
the atmosphere where it would gradually break
down to form carbon dioxide. PHILIP GINGERICH: Methane
and carbon dioxide are both powerful
greenhouse gases. They elevate the temperature
that further destabilizes more of the methane. Pretty soon you have
a runaway process going until you've exhausted
the methane that's built up. JV MARTIN: The worldwide
temperature boost changed the face of the planet. FRANCESCA SMITH: If you were to
come to Earth during the PETM 55 million years ago, you
would find that in Wyoming, rather than having very
dry and arid conditions, you would have vegetation that
was more similar to what you find in Panama today-- subtropical forests, very lush. PHILIP GINGERICH: This is the
time where horses and primates, our ancestors, and several
other groups of modern mammals first appeared. JV MARTIN: The warming
Earth sent evolution into a new direction,
one that would produce new species leading directly
to the ascent of man. Thick forests extended into
the Arctic and strange dwarfed animals flourished. But environmental change at
the Paleocene-Eocene transition had its losers as well. GERALD DICKENS: We come into
the Paleocene-Eocene boundary at the bottom of the ocean
and it's a mass extinction. Many of the organisms go
extinct and that's it for them. JV MARTIN: Warming of the
scale seen in the PETM would be considered
a global catastrophe if it happened today. But if Gregory Ryskin's
theory is correct and a methane release comes from
the sudden explosive eruption of a stagnant ocean
basin, the disaster would be swift and
far more violent. GREGORY RYSKIN: It's
a huge fountain. And a huge amount
of methane that would be expelled from the
ocean through those fountains. JV MARTIN: Few scientists agree
that a global-scale eruption in the open ocean is likely, but
there are other bodies of water where the phenomenon may
occur on a smaller scale. The Black Sea, for instance,
is being studied today for its methane content. GREGORY RYSKIN: The Black Sea
is essentially a stagnant basin. Since the Black Sea is
accumulating methane right now as we speak, it's easy
to guess that it was doing it a long time before, and perhaps
it was doing it for, say, a few hundred thousand years. JV MARTIN: In fact,
some scientists believe a deluge 7,000
years ago in the Black Sea gave rise to the Bible's
account of Noah's flood. Professor Ryskin
describes the night he found a parallel
to his methane theory in the Book of Genesis itself. GREGORY RYSKIN: Well I went back
home and found a place, Genesis 7:11, and I read the
sentence which says, on that day, all the fountains
of is a great deep burst forth. And I was amazed, because that's
exactly the picture of which I have for my
methane-driven eruption. JV MARTIN: Methane
concentrations in the Black Sea today are nowhere near enough
for another eruption soon. More likely, according
to Professor Ryskin, is an eruption on a similar
scale, perhaps an area the size of California. But it would happen
somewhere in the open ocean where the deepest waters are
twice as deep as the Black Sea. That means the water
under higher pressure could store even more
methane, holding the potential for a global disaster. The long history
of life on Earth is separated into periods,
epochs, and other divisions, each marking an extinction
or other change in evolution. The smallest of the divisions
is the geologic stage, and the boundary
between every stage is a target for the methane
eruption theory of Gregory Ryskin. GREGORY RYSKIN: I think that
every single stage boundary, which is marked by a large
or small mass extinction, is actually a result of
a catastrophic event. And I think that this
catastrophic event is a methane-driven oceanic
eruption, because there is no other simple mechanism
on the Earth which would lead to this kind of repetitive
wiping out of most of the life on the whole planet. For the last
half-billion years, there are about a mass
extinction every one or two or few million years. The last oceanic
eruption probably happened about
800,000 years ago, which means that
we may be overdue. And so we don't know whether it
should happen tomorrow or 1,000 years from now or 5,000 years
from now, we don't know. JV MARTIN: We also don't
know where it could happen. Other scientists agree with
Ryskin that our ocean bottoms are not well-known. So if a stagnant methane-bearing
basin is out there, it has not been identified. IRA LEIFER: The entire
sea floor has not been very well-explored. We don't understand all the
processes that occur down there by far, and research is
difficult, expensive, and has not been receiving
proper funding. JV MARTIN: Without knowing
where there are stagnant basins on the ocean bottom, the site
of the next eruption, should it occur, could be anywhere. A methane eruption in the
Pacific, for instance, could put the entire West Coast
of the United States in danger. It would begin in the
deepest part of the ocean, as water, saturated
with methane, may be shaken by an earthquake. Once the gas begins
bubbling out, there would be a chain reaction,
forcing fountains of methane and water to the surface across
an area the size of California. GREGORY RYSKIN: This
gas water mixture, which is produced
by the fountains, would be rolling away from
the place and all directions on top of the
surface of the ocean. It would be rolling
with a great speed. So tsunamis would reach the
West Coast of the United States, for example, and, say, Hawaii
in a very short time, perhaps a few hours. JV MARTIN: 2004's
Indonesian disaster raised tsunami consciousness
on the West Coast. North of San Diego,
the City of Encinitas has tsunami warning signs
posted near the beach even though the risk here
is considered moderate. But that's because most tsunamis
are caused by earthquakes. This one would be
very different. GREGORY RYSKIN: Well, the
tsunamis would not just be a one-shot thing
as they usually are. They will be coming on
continuously, days or maybe weeks. JV MARTIN: A
small-scale simulation in a tank at the University of
Michigan's Hydrodynamics Lab illustrates the tsunami effects
of the continuous methane fountains. Instead of one or two waves
generated by an earthquake, the methane fountains
would send wave after wave against
vulnerable coastlines for as long as the
eruptions last. Cascading tsunamis
from a Pacific eruption may first strike American
shores at San Diego. The low-lying terrain exposes
heavily-developed areas to extensive water damage. GREGORY RYSKIN: It is possible
to estimate that the flood waters may reach heights of
400 meters in a large eruption. JV MARTIN: At that
height, tsunamis nannies would cover downtown San Diego,
leaving only the city's 25 tallest skyscrapers
visible above the water. The tsunamis would hit
other exposed cities as well where whole populations would
face the sudden disaster. In time, the entire world would
be affected, as methane bubbles make ocean volumes
expand to push up sea levels around the globe. GREGORY RYSKIN: The total
sea level on the globe will increase by
about 35, 40 meters. JV MARTIN: The
methane in the water will take months to
bubble out completely, keeping sea levels as much
as 130 feet above normal. The world's coastlines
would be visibly altered as the oceans push inland,
flooding wide areas of densely-populated cities. In scenes reminiscent
of Hurricane Katrina, millions of people who
survived the tsunamis would be driven from their
homes along every coastline in the world. GREGORY RYSKIN: About
25% of the population of the Earth that lives
in the coastal area is in the 100-meter
elevation from the sea level. So 25% of the population of
the Earth would really be-- could be affected by
an eruption like that just from tsunamis
and the floods. JV MARTIN: But floods and
tsunamis are only a beginning. Next would come the
methane-bearing water clouds ready to ignite as soon as
they meet any random spark. Firestorms of methane
would follow the tsunamis to all the West Coast
cities and any place else on Earth where air currents
carry the volatile methane clouds. GREGORY RYSKIN: I
estimate that even in a reasonably small
oceanic eruption, this explosive mixture will be
able to cover the whole surface of the Earth with a layer
of about 50 meter thick. JV MARTIN: The methane
eruption itself is confined to one area of the ocean,
but the disaster it produces would be global. Though billions of
people could perish, mankind may escape
utter extinction. GREGORY RYSKIN: I'm
confident that a large part of the population of
the Earth will survive, but the damage will be
of a scale which has not been observed ever. JV MARTIN: The scenario
drawn by Professor Ryskin is almost too extreme
to contemplate. Although few scientists
agree with him completely, some are keeping an open mind. YOUXUE ZHANG: The mechanism that
he proposed may not be correct. And so there are some details
that may not be correct. The main hypothesis, it's still
a good one and a very plausible one. JV MARTIN: A theory that
predicts disastrous methane eruptions on a regular
basis may seem improbable, and if only a few
find it plausible, does that make it worth
serious consideration? Even if there is a small
chance that such a thing will occur, well the
consequences of it are so disastrous
that it certainly deserves funding on all levels. Only a global nuclear
war, perhaps, compares. JV MARTIN: Even if global
catastrophes are rare, ours is a planet where we know
such disasters have occurred in the past. With that as their motivation,
scientists worldwide will continue to search for
clues to understand why they happened, hoping they may
learn how we can survive the disasters of the future.
