[music playing] NARRATOR: America, paralyzed
by severe ice storms. Europe, gripped by a
frigid cold that drops like a bomb on the continent. Many experts believe
that we are on the verge of an abrupt climate
change, which could threaten our very survival. PETER SCHWARTZ:
England, France, Germany would begin to resemble
Alaska and Canada. NARRATOR: Scientists project
that within a few decades the climate could radically
spin out of control. If you're living on the edge
and you get just a little bit of a cooling, it can
push you over the edge. NARRATOR: There will be no
time to adapt or recover from the deadly cold. Abrupt climate change
is one of the great crises that our civilization
could face. It's hard to overestimate
the magnitude of the impact of this. [dramatic music playing] NARRATOR: Great
civilizations have been destroyed by sudden
and extreme climate changes. EUGENE LINDEN: People take
good weather for granted. And then nature changes things. And all of a sudden they're
off a cliff without a net. NARRATOR: Now the clock is
ticking toward a big chill, a new climate catastrophe that
could affect civilizations across the entire
planet and unravel the very fabric of society. PETER SCHWARTZ: We are
looking at an unending war in our future. KONRAD HUGHEN: The
changes that are coming are beyond what we have
learned to deal with. [dramatic music playing] NARRATOR: The Earth's
climate is far more fragile than people think. It's subject to
radical shifts that can be so quick and
extreme, that it can change the course of history. A potential big chill could
be caused by something as subtle as a
deviation in ocean currents in the North Atlantic. The climate catastrophe
might begin with temperatures bouncing up and down, from cold
to hot and back for decades. Paradoxically, as the
southern regions heat up, the northern areas
become much colder. Some experts project a 10
degree drop in average winter temperatures in some areas. The results, freezing winter
storms paralyze Western Europe, stinging winter temperatures
grip the Eastern Seaboard of the United States, raging ice
storms with high wind velocity batter New York, temperatures
continue to drop, Boston reels under the weight
of the most brutal winter in its history. As the relentless
winter persists, punishing snow and
windy ice storms blanket the entire
Northeast coast. In Europe, the
winters also stretch into months of unending
freezing temperatures. London's cold wet winters
twist into a deadly series of ice storms. Paris is frozen in stark
relief to what it once was. Berlin is a snow bound
relic of the past. Some scientists predict that
this sudden change in climate, including a big
chill in the north, could occur within our lifetime. PETER SCHWARTZ: I think there
are several things that people don't realize about the climate. First of all, that
it is changing. That that is a given. And the only question is how
fast and how far, where it will settle out. And that it can change
rather dramatically. NARRATOR: Ironically,
the same shift in climate may cause not only
near arctic conditions, possibly creating a mini ice
age in parts of North America and Europe, but also massive
drought and more severe storms in other regions. It's not only the speed at
which these climate changes will occur, some say within
a decade, but also the unpredictable
nature of the changes that make the impact
potentially lethal. As we move into the future,
if the climate state is such that we can have severe
storms and severe weather events coming in every
year, or every other year, that's not normally
what we deal with. And that's not
normally what society is prepared to cope with. And adapting to that kind of
extreme, is very difficult. We don't know what
to prepare for. NARRATOR: One massive
blizzard after another. And no time to
prepare, or recover, could be the new and deadly
winter scape on the east coast and Europe. PETER SCHWARTZ: Then the
question really becomes, what's the climate
of the United States? What is habitable on the earth? NARRATOR: This rapid change in
climate has happened before. Scientists call this phenomenon
abrupt climate change. LLOYD KEIGWIN: A good working
definition for an abrupt change is any change that occurs more
rapidly than society's ability to respond to it. NARRATOR: One of the
most extreme examples of abrupt climate change
occurred before the advent of modern civilization. About 14,000 years
ago, the earth was approaching the end
of its last ice age. Groups of Stone Age
hunter-gatherers roamed throughout
Europe and Asia foraging for food and game. But then suddenly, 1,200
years later, temperatures dropped as much as 18 degrees
in less than a decade. The plants and animals upon
which these early humans depended either died off
or moved to warmer regions. The humans who survived
migrated south. This radical drop in temperature
is known as the Younger Dryas event, named after an
arctic flower found in ice cores in Greenland. The event known
as the Younger Dryas is the poster child for
abrupt climate change. What's interesting about
this particular change is that the Ice Age
had already ended, and the Earth had
already begun to warm, and gone into its modern mode. NARRATOR: As the
weather began to warm, it suddenly flipped
to freezing cold. Literally the climate shifted
from Maritime to arctic over-- in the blink of an eye. And then stayed cold
for 1,300 years. And then just as
dramatically warmed. LLOYD KEIGWIN: And
then we were officially into this modern interglacial
warm climate epic. And why it ended is
not at all certain. NARRATOR: Scientists believe
that the Younger Dryas was caused by a change
in ocean currents. It was one of the most
extreme freezes since the end of the last Ice Age. The Younger Dryas is a dramatic
example of how the climate can bounce rapidly
like a bungee cord between deadly warm
and cold extremes. RICHARD ALLEY: It doesn't
always go smoothly. Sometimes it does boing,
boing, boing, boing. And then it'll stabilize
for a while at cold, and then it'll start up. And it'll go boing, boing,
boing, boing, boing. And then it will stabilize
for a while at warm. In the past we've
seen climate change like a light switch, where
conditions flicked on and off. And these flicks occur
extremely rapidly. And then we are in a new state. And that new climate
state can be irreversible. We don't just go back. NARRATOR: Following the
end of the Younger Dryas, the earth entered a protracted
period of relatively temperate climate. But there have been instances
of sudden chilling periods, including what historians
call the Little Ice Age. EUGENE LINDEN: Between
900 and 1300 AD, you had what was called
the Medieval Warm Period. Merchants were getting rich
enough to build castles, weather was good, population
quadrupled in Europe, people were taller,
they were living longer. Everything's going great. 1,000 years ago when the
Medieval Warm Period is on, you can take an open boat
and you can sail across from Scandinavia to Iceland. You're not running
into frozen ocean. You're not running
into lots of icebergs. NARRATOR: The seafaring
Vikings took advantage of the good weather to establish
farming and trading communities in Iceland. They expanded their territory,
sailing their large ships to Greenland. EUGENE LINDEN: Then
in 1000 AD or so, they moved into the New World. And they weren't really
prospering there. But they were there and they had
these two colonies in Greenland that were a staging area
to get to the New World. NARRATOR: Then around 1300
AD, the weather mysteriously began changing. Historical data taken from crop
yields and other public records show a small drop
in temperature. But this minor degree
change in temperature was enough to trigger the Little
Ice Age, a prolonged period of colder weather
in Europe that would have disastrous consequences. Ultimately, this
slight shift in climate would play a part in the
spread of the Black Death and the social upheavals that
would lead to the American and French Revolutions. Researchers from Woods Hole
Oceanographic Institution look for clues about
past climate change by digging sediment cores
from the ocean floor. They have discovered intriguing
evidence of the Little Ice Age. LLOYD KEIGWIN: The sea
floor is a repository for-- for shells of animals that
grew in the overlying waters and for-- and for sediments
that wash off land. And these layers
accumulate in the cores and we get a record that
might be 100,000 or even a million years long. NARRATOR: Samples of the
mud reveal a snapshot of the past climate records,
including extreme changes like the Little Ice Age. LLOYD KEIGWIN: We have records
of sea surface temperature, of deep ocean
temperature, of salinity. We have records of
volcanism, solar activity. There's-- there's countless
things that can be measured here. NARRATOR: The samples are then
radiocarbon dated in a particle accelerator. KONRAD HUGHEN:
Radiocarbon dating is a tool that allows us to
tie together climate records and changes in the Earth's
system from sediment cores and link those to the historical
record as far back as 40,000 years. LLOYD KEIGWIN: So we've
dated the bottom of the core at about 1,700 years
before present. And at that time,
this was the seafloor. So sediment is
continually accumulating. 1,700 years. 1,500 years. 1,000 years. 500 years ago here, about the
beginning of the Little Ice Age right up to today. And, you know, if you go
back in 100 years from now, there'll probably be a few
more centimeters of sediment accumulated at this location. NARRATOR: The subtle difference
in the color of the mud shows microscopic data pointing
to a change in ocean currents during the Little Ice Age. This evidence from the ocean
itself corroborates a one half to three degree drop
in average temperature. But this small
difference in temperature was the catalyst for a
shattering climate disaster that changed the course of
history and left millions dead. [dramatic music playing] [no audio/video] NARRATOR: Some
scientists predict a sudden violent
change in climate might lead to a big chill. Freezing temperatures
will grip Europe and the Northeastern coast
of the United States. Life will come to a standstill
in a terrifying frozen wasteland. It has happened before. Generations had prospered
in the stable weather of pre-Renaissance Europe. But in the 1300s, without
warning, that predictable world was turned upside down by
the so-called Little Ice Age. EUGENE LINDEN: One
of the things that happened was that you had this
whipsaw going to warm, going to cold. 1308 was cold. 1315 was warm. 1317 was cold again. And creatures and other things
respond in different ways. You know, you get crops
rotting in the field if it gets too wet, or
germinating too early, or never germinating at all. NARRATOR: The climate rapidly
switched back and forth between cold and
warm, wet and dry. But this initial erratic
climate was only a prelude to catastrophic changes
of epic proportions. Over the next few centuries,
the weather continually fluctuated at temperatures
between 0.5 and three degrees lower than normal. This small change was enough
to awaken an icy killer. KONRAD HUGHEN: Throughout
the Alps and throughout parts of Europe, and in fact in
North America and Canada, the eastern Canadian
arctic, we see evidence that during the Little
Ice Age glaciers advanced. NARRATOR: The difference
of only a few degrees triggered a self-perpetuating
feedback cycle. You make a little more ice,
it reflects more of the sun. By reflecting the sun, the
sun is not warming us up. And so it gets colder,
so you make more ice. NARRATOR: As the
glaciers expanded, the Vikings took the first brunt
of the climate's deadly chill. They switched from being
a farming economy to eating a lot from the sea. Because they were having
troubles raising enough things on their farms, apparently. NARRATOR: But as temperatures
continued to drop, storms and freezing winds
blasted the settlements. Even the sea held
no hope of survival for the starving Vikings. LLOYD KEIGWIN: Around
Iceland, sea ice expanded. And the people couldn't
get out and go fishing. And they had open boats,
not boats with decks. So they were particularly
vulnerable to bad weather. NARRATOR: After
decades of expansion, battle ax wielding, pillaging,
and plundering Vikings were defeated by a sudden
drop in temperature. EUGENE LINDEN: Well, 10
super cold years, including one of the coldest years on
record ever in about 1355 AD, shut down the Western colony. And 100 years later, the
more southerly eastern colony shut down. NARRATOR: The Vikings who
survived migrated south, assimilating into populations
living in continental Europe. Their fearless culture
receded into history. If it hadn't been for
the Little Ice Age, the Vikings may have continued
settling in the new world. And today's America would
be a very different place. By the end of the
14th century, Europe was buckling under freezing
temperatures all winter long. [music playing] In a chain reaction ignited by
the cold and stormy weather, one calamity followed another. Crops failed and food
shortages spread across Europe. The freezing cold
blasted through Asia. But that was only the beginning. Relentless storms killed
at least seven million. The resulting floods produced a
horrific and infamous blowback effect on Europe. EUGENE LINDEN: Everybody's
familiar with the Black Death. But the lesser known
story, of course, is the role that climate may
have played in unleashing it. [dramatic music playing] NARRATOR: The Black
Death, or the plague, was a devastating pandemic
that ravaged Europe during the mid 14th century. The drop in temperature
changed weather conditions, causing storm patterns to
shift and intensifying. In the early 1300s, Asia
had a record breaking series of torrential storms
and subsequent flooding. Rats carrying the plague
thrived in these conditions. EUGENE LINDEN: The animals
that react the first, are the ones that
reproduce by the zillions and reproduce very rapidly. Whereas the longer live,
slower reproducing animals, tend to lag. And so weedy species
of ev-- of every sort seem to take advantage of
climate change and flourish. NARRATOR: Rats on
ships traveling the trade routes spread the
disease from Asia to Europe. An already starving
and weakened population was no match for
the Black Death. Within five years, the plague
had killed between 25 and 34 million people in Europe. One third of the population. An estimated 40 million more
died in North Africa and Asia. Generation after
generation suffered the relentless pounding of
extreme cold and wet weather, pushing the starving
peasant to his limit. EUGENE LINDEN: Then
there are intense storms and incessant rain. Crops are rotting in the field. There's so little sunlight
that he can't make salt in the summer to
preserve anything. Diseases, molds, blights,
and everything else are beginning to afflict him. People fell into robbery. They lost their land. Starvation, they started
eating their livestock, dogs, and cats. And at some points, they
even ate each other. NARRATOR: Sophisticated European
societies quickly crumbled, scratching at the
edges of mere survival. Starving peasants revolted
against the aristocracy. The political unrest and an
economic crash in England were factors in the
American Revolution. And it was the poor
of 1789 France that fueled the French Revolution. The tragic scope of the
Little Ice Age was staggering. Millions died horrible deaths
simply because the temperature dropped a few degrees. LLOYD KEIGWIN: If you're
living on the edge and you get just a
little bit of a cooling, it can push you over the edge. EUGENE LINDEN: Little changes
in global temperatures can have an enormous effect. A temperature change of
five to nine degrees, which is also within the
realm of possibility, would just be unimaginable. NARRATOR: The small
drop in temperature that triggered the Little
Ice Age may have been caused by a dimming of solar
output linked to a change in sunspot activity. Another factor that intensified
the cooling was something else no one could have
predicted or prevented. During the Little Ice Age, at
least three massive volcanoes erupted. Mount Vesuvius in 1631. Mount Tambora in 1815. And Krakatoa in 1883. All spewed particles and gases
into the upper atmosphere. These particulates
reflected the sunlight back into the atmosphere,
cooling the earth. If you put a lot of
volcanic debris high into the northern
hemisphere, it's going to be everywhere in the
northern hemisphere within just a couple of years. No matter what part of the
earth is facing the sun, day or night, it's still going
to get less sunlight. NARRATOR: After six centuries
of death and deprivation, the weather finally
began to warm. The Little Ice Age likely
ends because the volcanoes quiet down. They're not blocking the sun. And the sun brightens
up a little bit. So you have warming
coming out of 1850 or 1900 into the early
part of the 1900s. NARRATOR: The Little
Ice Age may be over. But some scientists see it as
a preview of what could occur again, this time with even
more devastating consequences. [dramatic music playing] [no audio/video] NARRATOR: Experts believe
that in the future, a big chill could create a
series of catastrophic weather events, from freezing
blizzards blanketing London, to an eerily empty New York
buried in snow, to a drought ridden Midwest. But this would not
be the first time that dramatic climate changes
threatened an entire way of life. Since the end of
the Younger Dryas, about 11,500 years
ago, our world has had a relatively temperate
climate, providing a foundation for the growth of
modern civilizations. But within this time, scientists
have uncovered other periods where average temperatures
flicker on and off between coolings and warmings. As we look back over
the last 10,000 years, most of the coolings
have been fairly small. NARRATOR: While Europe's
Little Ice Age caused widespread
deprivation and death, it did not mean the
end of civilization. But there have been rare
episodes when extreme changes in temperature have literally
destroyed entire societies. [dramatic music playing] Just such a change may
have caused the collapse of the great Mayan empire. EUGENE LINDEN: As of 900
AD, the Mayan civilization had been around for
about 1,200 years. It had risen and fallen
several times before that. But it always bounced back. 900 AD it disappeared
and never came back. So there's been
great speculation about what did in the Mayans. NARRATOR: The fall of the
Mayan civilization of 3 million people may have been one of
the most striking examples of a deadly climate disaster. Tucked in the rainforests of
what is now Central America, the early Mayans developed a
sophisticated urban society. Without the use of
iron or the wheel, the Mayans built
sprawling cities, each with large plazas
surrounded by majestic temples and pyramids. Why this advanced
civilization disappeared has been a mystery
for centuries. Many archaeologists speculated
that the Mayans imploded with civil unrest,
warring factions overtook civil society, and
the fragile social structure collapsed in chaos. EUGENE LINDEN: There's over 100
different theories of the Mayan decline, most of them being
that they did it to themselves. Because they were a somewhat
cruel civilization in some respects. NARRATOR: But there were
other natural forces at work that were beyond the
power of the Mayans to control or understand. Recent research
in climate history has revealed a new
angle on an old mystery. Researchers are
still investigating. But some believe that a minute
lowering in global temperatures may have triggered the
end of the Mayan empire. The biggest challenge
for the Mayans was how to manage
their water supply through the wet rainy seasons
and the occasional droughts. In different regions of
the Mayan civilization, the cities were built near
natural water sources, such as sinkholes where water
would be collected naturally and be available even
through the dry season. NARRATOR: But in some
parts of the region, groundwater was inaccessible. With access to
groundwater limited, the Mayans were
dependent upon rain as a source of fresh water. In order to efficiently
utilize this precious resource, the Mayans built an
intricate system of canals to irrigate their
farms and cities. With the help of steady
rains, the Mayans evolved from a mere
subsistence society to a flourishing sophisticated
culture with an avid interest in literature, art,
mathematics, and astronomy. The Mayans charted the
orbits of the stars through their
observatories, even orienting their
religious buildings along astronomical lines. But the Mayans had
no way of knowing that their magnificent culture
would come to a crashing end, all because of a change that
they themselves may have noted. EUGENE LINDEN: What you see is
a recurrent pattern in history in which people take
good weather for granted. They're fruitful,
they multiply, they expand beyond the carrying
capacity of the land, essentially. NARRATOR: For hundreds of
years, the mighty Mayan people depended on the
predictable rain cycle to sustain their vast
empire in Central America. Then they were hit by extended
periods of devastating drought. Paradoxically, their
drought may have come about as a result of a
drop in global temperature. Some suggest that Mayan
astronomers themselves noticed a slight change in the
appearance of the sun. Some researchers believe that
there had been a reduction in solar radiation hitting
the planet's surface, causing a shift in wind patterns. In the north, temperatures
may have cooled. But for the Mayans, the
effect was the opposite. Rain clouds stayed south
creating a devastating drought in the Yucatan. KONRAD HUGHEN: We've been able
to identify periods of three or six or nine years in a row
where the rainy season failed to come. And each one of these
intervals of drought coincides with a period
of major collapse in one of the regions of
the Mayan civilization. NARRATOR: As the
droughts continued, the rulers began to lose
their grip on the people. EUGENE LINDEN: As they failed
to deliver on their promises of water in the dry months,
and the reservoirs would not be replenished adequately
during the summer, farmers themselves
started to move away. NARRATOR: Many scientists
speculate that the warring Mayan civilization was
already beginning to collapse. Deforestation, rampant disease,
and their own warlike culture contributed to their demise. But the actual
tipping point may have been the change in climate. These bad severe
drought events occurring over
several years in a row could have ultimately resulted
in the civilization no longer being able to deal with
the societal stresses. The drought events could
easily be an explanation for what caused
the Maya ultimately to disappear entirely. NARRATOR: The Mayan
empire was left in ruins, leaving only their grand
pyramids in silent testimony to who they once were. Could we be the next victims of
an extreme climate catastrophe? [dramatic music playing] [no audio/video] NARRATOR: Experts warn that a
temperature drop of only a few degrees could catapult parts
of the northern hemisphere into a new Little Ice Age
within just a few decades. The relatively mild winters
of the Eastern Seaboard and Western Europe could warp
into icy barren landscapes. Scientists believe that the
next big chill would have its beginning in the oceans. 70% of the Earth's
surface is ocean. 90% of all rain
falls into the seas. It is a colossal reservoir
of water carrying heat all over the planet. A huge ocean current
system, known as the thermohaline circulation,
which includes the Gulf Stream, circulates warm water north
from the equator giving our Northeastern Seaboard and
parts of Europe relatively temperate climates. London, England,
and Calgary, Canada are on the same latitude. Yet London is much
warmer on average. The reason? The thermohaline
circulation, which brings warm water and warm air
north to the British Isles. As the heat is absorbed
into the atmosphere, the surface water becomes
colder, saltier, and dense. It sinks deeply, in effect
pulling the current down behind it. RICHARD ALLEY: So in the winter,
as the water gets really cold, colder makes it contract. And contracting makes it
denser and then it sinks. And then warm water
flows up to replace it. NARRATOR: In a
self-perpetuating cycle, the thermohaline circulation
then moves south where it warms again at the equator,
and continues its cycle back up north. This immense system is dependent
upon a delicate balance between warm and cold water,
and fresh and salt water. Disrupt any part of the system,
and you could create a mini Ice Age in parts of the
northern hemisphere. And there is one change
already happening. Global warming is
raising sea temperatures. RICHARD ALLEY: The
oceans are warming. Almost all the
glaciers on the planet have gotten smaller
over the last 100 years. You're getting reductions
in sea ice in the Arctic. Things are happening
earlier in the spring and lasting farther into the
fall than they did in the past. And so there's this great
number of indicators that say, yes, the planet is warming. NARRATOR: This rise in
the ocean temperatures may cause a shutdown of the
thermohaline circulation, the system that brings warmth
to the North Atlantic region. RAY SCHMITT: The total
heat capacity of the ocean is 1,100 times that
of the atmosphere. So in my mind, we really should
be trying to understand what's going on in the ocean to
understand our future climate. NARRATOR: Researchers from Woods
Hole Oceanographic Institution utilize many tools to
study the changing ocean. Remote controlled devices,
called floaters, track changes in the ocean's condition. They're sort of like weather
balloons for the ocean. The drift at depth
for 10 days, then come to the surface recording
the temperature and salinity as they rise. And they transmit that
data to a satellite. And we have a program to
deploy thousands of these around the global ocean, and
thereby, for the first time, monitor the ocean heat and salt
content on a continuous basis. This is a revolutionary new tool
for seeing climate processes acting in the ocean. NARRATOR: Using the data
transmitted by tools like floaters, scientists create
computer models that track and then project
climate changes. Recently, researchers
have found evidence of a disturbing development. Global warming is melting
glaciers and ice sheets, causing an increase
in fresh water flowing into the thermohaline
circulation, a process they call freshening. This fresh water could throw
off the critical balance between temperature and
salinity that powers the thermohaline circulation. PETER SCHWARTZ: What it means
is that those warm waters no longer flow north. And they stop much
further south. And so all that warmth
that would otherwise warm the northern hemisphere
stays in the south. Which means, for
example, there's more energy in the atmosphere
there, more extreme storms, and so on. But critically, much
colder in the north. NARRATOR: If the thermohaline
circulation is disrupted, an abrupt climate change as
intense as the Little Ice Age could result. Temperatures
could drop dramatically in the North Atlantic in
as little as a decade. KONRAD HUGHEN: If the
thermohaline circulation was to shut down, the average
temperature changes resulting of that could be anywhere
between eight to 12 degrees possibly. But that would be on average. And clearly the extremes
that could result from an average temperature
change like that could be well beyond that. England, France,
Germany would begin to resemble Alaska and Canada. And those parts of the
world, particularly Alaska, might even get colder still. NARRATOR: In the United
States, the Northeast coast would be hit the hardest, with
extreme temperatures and more intense blizzards and storms. KONRAD HUGHEN: For example,
severity of northeaster storms could easily increase
in a condition where you had an increased
storminess, increased wind velocities, impacting the
eastern North America. NARRATOR: But this big chill in
the northern regions of Europe and America would only be a side
effect of the real devastation in other parts of the world. In the Pacific, a warmer ocean
will intensify the El Nino rainstorm cycle that
historically batters the Pacific coastline. EUGENE LINDEN: Even a two degree
change, if we were so lucky, would be double the intensity
or more of the strongest El Nino we've ever felt. In 1998, there
was a very strong El Nino. It did $100 billion
damage around the world and killed tens of
thousands of people. So even a very slight variation
from the norm in global weather can cause a lot of damage. NARRATOR: In the South
Atlantic, warmer oceans will mean intensified
hurricanes and massive storms. RAY SCHMITT: The fact that we
have a great deal of heat built up in the ocean means that
there's plenty of fuel for more intense hurricanes. So it seems inevitable
that strong hurricanes are in our future. KONRAD HUGHEN: If we get
not just one Katrina, but if we get five
Katrinas per year coming into different regions
of the Gulf Coast, or in fact, shifting to where now
these storms are impacting along the Eastern Seaboard
and coming into Washington, DC and New York City, then the
consequences would be severe. NARRATOR: Next, using the latest
in scientific data and computer visualizations, we get
a terrifying glimpse at the impact of extreme
and abrupt climate change in our future. Not just freezing temperatures
in the north, but also monster hurricanes, massive storms, and
in some areas, endless drought. EUGENE LINDEN: If you look at
the potential for the damage done by climate
change, you can easily see how climate change could be
a weapon of mass destruction. [explosions] [no audio/video] NARRATOR: From the Younger Dryas
event over 12,000 years ago, to the more recent
Little Ice Age, extreme climate change has
had catastrophic effects on humankind. KONRAD HUGHEN: These
climate changes that may occur in the future are
not something that we can say, oops. We don't mean it. We want to go back now. We may enter a place
where, in fact, the thermohaline
circulation has shifted. And in the past, we've seen that
those conditions have lasted for thousands of years. NARRATOR: Using the latest
research, expert predictions, and computer animation, we will
now show how this worst case scenario might unfold. This abrupt climate
change is triggered when warming temperatures cause
the polar ice sheets to melt. Fresh water melting
from the glaciers interrupts the delicate
balance of the thermohaline circulation, shutting off
warmth to the North Atlantic. Average temperatures in
Europe and North America slide dangerously down. With the Gulf Stream no longer
warming the Atlantic Seaboard, winters are much more severe
along the Northeast coast of the United States. On the whole,
the further north we get will be colder,
drier, and windier. And you begin to think of
everything kind of North of the Mason-Dixon line
beginning to look like Siberia. Frankly, the
habitability of some of the major northern
cities begins to diminish. NARRATOR: In New York,
winter temperatures could begin as early as October. By November, snowfall
in New York City could reach record
breaking levels. You could have already
increased winter storminess affecting New York City. And what could be a normally
paralyzing two feet of snowfall could become six
feet of snowfall. NARRATOR: Wind
velocity increases. And storms batter the coast. The Statue of Liberty is no
longer a beacon of freedom, but a frozen marker for
a once vibrant city. Europe's urban centers,
particularly London, reel under frigid windstorms
and freezing temperatures. Suddenly Britain, which
is already tough enough in the winter, becomes really
miserable in the winter and has no summers. And suddenly begins to
get much, much colder. NARRATOR: For the first
time in more than a century, the Thames freezes over. This sudden and
extreme climate change could subject Europe and the
Northeastern United States to overwhelming winters
for centuries to come. The same warmer oceans that
lead to a big chill in the north will bring catastrophic changes
across the planet, changes that will affect every person,
every nation, and every form of weather. They will be just as devastating
as any chilling effect. In the west, warmer oceans
lead to persistent El Ninos. Storms pound the
Pacific coastlines with torrential rains
all winter long. The San Gabriel Mountains on the
north side of the Los Angeles basin are one of the steepest
mountain ranges in America. With a powerful
El Nino condition, Los Angeles could be
buried by thick mudslides. KONRAD HUGHEN: These things
increase exponentially. So the amount of runoff
could increase exponentially. We're talking about 10 times
more and then 100 times more. So the ability of
these mudslides to effect entire parts of
the city is not impossible. NARRATOR: The streets of
Los Angeles become rivers of mud and floodwater, crushing
everything in their paths. Ironically, the coastal deluges
caused by the El Nino condition will have an opposite impact on
the interior of the continent. Bringing devastating droughts. The breadbasket of the
American Midwest disappears. Like many other high crop
yield regions in Canada, India, and the North China Plain,
year after year of drought erodes the land. We have 6 billion people
getting 40% of their sustenance from, essentially, five staple
crops grown in just a few bread baskets around the world. So if drought actually
does intensify in those breadbaskets, we have
90 food importing nations that are going to have big
trouble feeding their people. NARRATOR: Warmer oceans
create powerful storms. Hurricanes and cyclones
reach extraordinary strength. PETER SCHWARTZ: Most
places in the world, people live within about 100
miles of the ocean. It doesn't matter where
we are, the population lives close to the sea. China, Japan,
Europe, and America, and Africa, everywhere. And those are the places that
are most vulnerable to climate disruption. They're the ones that are
going to be hit the hardest. NARRATOR: One catastrophe
slams into another like a pinball
hitting its target and ricocheting to the next. EUGENE LINDEN: And so you
envision a situation where you have the west coping
with its water problems, the hurricane zone coping
with hurricanes, the Northeast coping not just with windstorms
but with hail storms and ice storms, which are
also impose a burden. The Midwest coping with the
swarms of tornadoes, which causes an enormous amount
of insurable damage. NARRATOR: Scientists estimate
that the carrying capacity of the planet, how many people
its natural resources can actually sustain, is
approximately eight billion. Some projections indicate that
catastrophic climate change could reduce the carrying
capacity to 2 billion people. Only a third of the
world's current population would be able to survive. PETER SCHWARTZ: As we've seen
throughout human history, it is changes in carrying
capacity that lead to war. When people exhaust
their local ecosystems, the first thing they do
is raid their neighbors. And in this case, we'll
be fighting it out over food and water. 6 billion people are going to
have to get off the planet. And the way 6 billion people
get off the planet is war. This is why I think climate
change is so urgent. I mean, it's a
recipe for conflict. If we fail in preventing
the worst case scenario, we are looking at an
unending war in our future. NARRATOR: This
vision of the future is a terrifying world where
the climate we all depend on suddenly turns against us. A horrific existence where only
the strongest and the luckiest survive. There still may be time to
take steps to avoid this fate. If not, we, like other
civilizations before us, may fall victim to the
implacable force of nature and of catastrophic
climate change. KONRAD HUGHEN: If we have long
term changes and increased extremes coming from
multiple different sources, this is where we may be
in for real surprises. And our society does not
deal well with surprises. [dramatic music playing] [no audio/video]
