All language subtitles for D D S02E08 El Nino 1080p AMZN WEB-DL DD2 0 H 264-playWEB_track3_[eng]

What connects
seemingly random events

like floods
in the United Kingdom,

droughts in Africa,

wildfires in Canada

and cyclones in the Pacific?

A boy.

"El Niño" in Spanish.

It's the innocent-sounding name

that Peruvian fishermen gave

to a climate phenomenon that
regularly devastates our world.

There is no single phenomenon
in the world

that can affect
global weather patterns

as much as El Niño

and is, therefore, associated

with as many natural disasters
as El Niño is.

One major El Niño event

that started in 2015
and which only ended in 2016,

contributed to catastrophic weather events

right across the globe.

El Niño of 2015-16
was one of the major

and most intense El Niños

that we've seen
in the historical record.

It contributed to the longest
coral bleaching ever recorded,

stretching across the oceans

from Florida Keys
to the Great Barrier Reef.

Africa, Malawi, Zimbabwe,
South Africa,

Mozambique and Ethiopia all
suffered devastating drought,

inflicting hunger
and disease on millions.

South America
struggled to cope

with both drought
and extreme storms.

The Pacific Ocean's vulnerable,
low-lying islands

were hit by several cyclones,
one after the other.

And southeast Asia recorded

the largest emissions
of wildfire and smoke ever.

So extensive
was El Niño's impact

that it even played a part
in major disasters

across Europe.

The United Kingdom was hit
by wave after wave

of record-breaking storms
and floods.

Floods can kill.
Floods annihilate.

They destroy.
They're incredibly dangerous.

In this episode of
Deadly Disasters,

we will look
at this climate phenomenon

that has affected
the entire world for millennia.

Our experts will look at some

of the most catastrophic
consequences of El Niño,

and its little sister,
La Niña.

another climate event

with devastating effects
around the globe.

Many of them
are immediately felt,

and they cause death
and destruction and disruption.

We will examine the differences
and similarities

between these two
climate-changing incidents.

We will consider
how different countries

have managed their impacts,

particularly in the developing world,

where resources
can be stretched thin.

Eyewitness reports will tell
the human story behind El Niño

and the personal toll
these disasters take.

El Niño is a climate phenomenon
that happens every few years,

when the waters in the eastern
tropical Pacific Ocean

get unusually warm.

Normally,
this warm water,

and the rainy conditions
it causes,

are in the western Pacific.

There, the sea level
is naturally higher.

In fact, normally around
40 to 50 centimeters higher

near Indonesia than Ecuador.

This is, in part,
because of strong trade winds

blowing westward
across the Pacific.

They push water
toward Asia and Oceania,

where it gathers and creates a
slightly tilted ocean surface.

El Niño causes droughts
in normally damp areas

in the eastern Pacific,

such as Indonesia
and Australia,

while normally drier places,

like South America's
west coast,

endure devastating floods.

But it also impacts the global
atmospheric circulation.

It can weaken
the Indian monsoon,

while bringing heavy rain
to the western United States.

We are only just beginning

to understand
this powerful phenomenon.

Essentially, El Niño
is quite a new science.

El Niño have only really been
known about for about 100 years,

and it's only been observed
properly for about 40 years,

during which time there's been
maybe four big events.

The first recorded
scientific discussions

of El Niño were in the 1890s,

between the Lima
Geographical Society

and the International
Geographic Congress.

But we now know that it
stretches at least as far back

as 10,000 years,

to the beginning
of the Holocene Epoch,

and the end
of the last Ice Age.

We have detected
chemical signatures

of increased rainfall
and warmer seas

in coral samples and other
paleoclimate indicators

since the previous Ice Age.

Climate scientists
have also shown

that tree-ring records
from North America,

especially from the Southwest,

match the intensity
of El Niño events

over the last 1100 years.

These tree rings coincide well

with the 150 year
sea surface temperature records

we have from the Pacific.

During El Niño,

the warmer surface temperatures
in the eastern Pacific

change the atmospheric
circulation.

This causes
unusually wet winters

in the southwest United States,
and thus wider tree rings.

This research was used to help
improve El Niño prediction

in climate models.

Predicting its likely events

over a few months ahead
is now normal.

But our recognition of El Niño

and its impacts is helping us
look at our history

with fresh eyes.

For instance,

we know that
from 1789 to 1792,

the South Asia monsoon
failed many times.

Research suggests the El Niño

influenced a mix
of climate anomalies,

and unusual weather
led to crop failures in Europe.

This, in turn,
became the catalyst

for some of the troubles
and desperate anger that,

in 1789, erupted
into the French Revolution.

El Niño has been linked
to at least three large famines

in the late 19th century.

British and Indian officials

noted that extreme weather

and the collapse
of monsoon circulation

resulted in great droughts
and floods.

Between 30 to 60 million
people died in China,

India and Brazil.

Hundreds of millions
endured hunger.

It was only in the 1960s

that scientists
definitively linked

the alternating warm
and cool patterns

in the Pacific waters

and the atmospheric
circulation.

At least 26 El Niños were
recorded in the last century.

In 1957-58,

El Niño caused serious damage

to the Californian
kelp forests.

It was only in 1982-83

that scientists were able
to study a major El Niño

as it was
actually taking place.

The unusually warm waters
in the Pacific

forced fish to seek out
colder waters to survive.

On Christmas Island,

sea birds abandoned their young

to fly over the Pacific
desperately searching for food.

Almost a quarter of the fur
seal and sea lion populations

off the Peruvian coast
starved to death.

Some of the biggest effects
on wildlife

that we've known about
for the longest with El Niño

is what happens off Peru.

You have deaths of sea birds.

You have deaths of seals,
and in some years,

collapses in population
of Galapagos penguins.

Indonesia and Australia
faced terrible droughts

and Southeast Asia
shut down some of its airports

because of the thick plumes of
smoke rising from forest fires.

El Niño is associated
with extreme weather

and natural disasters in many,
many countries in the world.

In Spanish,

"El Niño" translates
as "The Child" or "The Boy."

The name was given
by Peruvian fishermen

who noticed the occasional
warming of the ocean

around December

and made the connection
to Christmas and Jesus.

El Niño and La Niña,

which translates
to "The Girl,"

are opposite phases

of the El Niño Southern
Oscillation cycle of ENSO.

ENSO is the name
for the temperature variations

between the ocean
and atmosphere

in the Equatorial Pacific.

El Niño is the warm and La Niña
the cold phase of the ENSO.

El Niño is officially declared

if the eastern tropical
Pacific's surface temperature

rises half a degree centigrade
above the long-term average.

One of the most severe El Niño
events was in 1997-98,

when the Pacific
heated up remarkably,

by more than three degrees
centigrade.

The effects of climate change

on the cycle
are not yet fully established.

Some scientists
believe climate change

will make ENSO events
more frequent and intense.

If right, it is likely
that the economic,

environmental and societal impacts

will only get more extreme.

The three most deadly
El Niños,

1982-83,

1997-98 and 2015-16

were not just because

of the scale of the chaos
they wreaked.

But also because
of how unpredictable

their effects were.

It is not certain what tips

the unstable Pacific Ocean
atmosphere system

into El Niño,

but a weakening of normal trade
winds that blow west is key.

For instance,
in 2014,

a large group of very strong
thunderstorms over Indonesia

may have been the trigger.

An upwelling or
upward movement of ocean water

can mix upper and lower levels
of seawater together.

This brings cool
and nutrient-rich water

from the bottom of the ocean
to the warmer surface.

There, it supports large
populations of phytoplankton,

zooplankton, fish,
and fish-eating seabirds.

Every few years,

normal upwelling in the Pacific
Ocean is affected by ENSO.

During an ENSO,

the trade winds that blow
from east to west weaken.

This allows the warmer waters
of the western Pacific

to move towards the
western coast of South America.

This suppresses
the normal upwellings of cold,

nutrient-rich water.

The marine food chain
is disrupted.

Warm waters force fish down
to colder, deeper water.

Seals suffer as they lose
their food source.

In the same way,
the fishing economies

of countries such as Peru
and Ecuador are also hit.

We are still trying
to work out

the relationship between
El Niño and climate change.

What will happen to El Niños

under climate change,
global warming,

is a question
that many people ask.

Some studies are suggesting

there may be an increase
in frequency and intensity,

but other studies suggest that
that may not be the case.

So at the moment,
there isn't a strong consensus

about future behavior.

But the global system
is changing

because of global warming,

so we're very likely
to see a change

in the patterns of El Niño.

We know that a rise
in global temperatures

leads to an increase
in sea surface temperatures.

This is what sparks
the El Niño phenomenon.

The relationship between
El Niño and a change in climate

is somewhat cyclical.

Oceans act as carbon sinks:

they capture and store carbon

as dissolved CO2.

And carbon dioxide dissolves
more easily in colder waters.

During El Niño,

sea surface temperatures
increase.

This causes less CO2
to be dissolved.

The result is more carbon
dioxide in the atmosphere,

which causes global warming,

which in turn
leads to the climate changing.

Bushfires sparked
by the El Niño effect

also release
large amounts of CO2,

which in turn can lead
to greater global warming.

ENSO is one of the most
important phenomena

affecting our global climate.

It impacts
the atmospheric circulation,

which leads to changes
in temperature and rainfall.

The equatorial Pacific climate
behaves as a "coupled system."

This is because
the states of the ocean

and the atmosphere
depend on each other.

Some research
suggests El Niño events

are increasing in both
intensity and frequency,

resulting in increased
extreme weather events.

For instance,
unusually hot weather

is becoming more frequent
in Sri Lanka.

Certain regions have suffered
record temperatures,

as well as very heavy rains.

These extreme events
cause severe damage to crops,

depriving farmers
of a stable income.

Fishermen also suffer
when heavy rains

stop them from going to sea.

Natural disasters
such as floods

and landslides
become more frequent,

leading to loss of lives
and homes.

Diseases spread,
roads are blocked,

food prices soar,

and countries' vital
infrastructures are destroyed.

In 2015, El Niño struck
with particular ferocity.

Its effects were widely felt

and devastated vast areas
across the globe.

There was
a very extensive disruption

to the rainfall patterns.

And that was associated
with food security problems

throughout the globe,

particularly
in parts of Indonesia

and also parts of Africa,

with up to about
60 million people

faced with
food security issues

directly associated
with that event.

Countries across
southern Africa

experienced a bewildering array
of extreme weather.

South Africa experienced
one of its worst droughts

for 30 years.

Many small farmers
went out of business.

The government declared
five out of its nine provinces

drought disaster areas
for agriculture.

Dams were at an all-time low.

Thousands of hectares of land
were left with brittle stalks

from the previous
year's harvest.

The effects on wildlife
were dramatic.

Impala and hippopotamuses
grew emaciated.

Buffalo and hippopotamuses
died in droves.

But jackals and crocodiles

thrived on the increased
food sources.

The United Nations warned

that about 50 million people
faced hunger

across southern
and eastern Africa,

as the continent struggled with
its worst drought in decades.

One of the things
about El Niño

is that it does affect
very large geographical areas,

and so if we take the example
of southern Africa,

you have a drought occurring
across multiple countries.

And that can lead
to additional problems

to what you might find
just internally

if the drought occurs
within the country.

The worst hit was Ethiopia.

There, more than
2 million children

needed treatment
for malnutrition

and over 10 million people
needed food aid.

If the situation
continues like this...

we need the international
community's support.

The crisis even hit Ethiopians

not at immediate risk
of going hungry.

3.9 million children
and teenagers

no longer had access
to education.

These problems
don't go away overnight.

They don't go away in a decade.

I mean,
this is a long-haul process.

Somalia, Sudan,
and Kenya's crops also failed,

leaving a total of more
than 20 million people

food insecure in the region.

The drought took many
officials by surprise.

Although El Niño
had been forecast,

it normally brings more rain
to the region, not less.

When El Niño strikes,

it often exposes weaknesses
in countries' infrastructures.

The 2015-16 event

brutally revealed Zambia's
overreliance on hydropower.

Ninety-five percent
of the country's energy

was generated this way.

When the droughts hit,

the dammed lakes
couldn't cope.

Water levels
in the Kariba dam,

one of Zambia and Zimbabwe's
main sources of hydropower,

fell to a record low
of 12 percent in January 2016.

We're seeing a drastic
reduction, that's very scary.

And that tells me we're doing
something wrong as a country.

We're doing something wrong
as a region.

And perhaps, we're doing
something wrong globally.

And therefore,
this is a call to action

for us to do everything
that we must

to reduce
the global carbon emissions

to the minimum levels.

Industry was also badly hit.

In Zambia,
because of the impacts

of the El Niño
on the hydropower,

they had an overall impact
on national GDP

of between 1 and 2 percent.

Zambia's copper
mining industry

accounts for
almost three quarters

of the country's
foreign exchange earnings.

It was crippled
by the power cuts.

In September 2015,

the mining giant Glencore
made a staggering announcement.

As owners of a large part of
Zambia's Mopani Copper Mines,

they planned
to lay off 3800 workers.

The Anglo-Swiss company

laid the blame largely
on the power shortages.

Zimbabwe, famously once
the region's breadbasket,

was one of the countries
worst hit.

The country's president,
Robert Mugabe,

declared a state of disaster.

In less than a month,

people needing food aid
rose from 3 to 4 million.

Even cocoa bean yields
were badly affected,

meaning its price
hit a four-year high

as a result of the drought.

And production was lost

in the world's major cocoa
producer, the Ivory Coast.

Farmers whose families
had relied on the cocoa bean

for generations were forced
to hunt for other work,

often illegal and dangerous,
or starve.

Such was the scale of
the destruction

that in the summer
of 2016,

the southern African countries
launched an emergency appeal.

They asked for $2.8 billion,

to help them feed
the almost 40 million people

suffering in the worst regional
droughts for 35 years.

But the very scale
of the droughts

made giving help
particularly difficult.

International organizations

despaired of providing
resources to match the need.

Children were forced
from home,

leaving healthcare,

security and loved ones behind.

Put simply,

the scale of the crisis
far outstripped

the capacity of communities

and the resources
of the governments.

In under a year, El Niño

was putting decades of global
development gains at risk.

This double contradiction can
be seen vividly in Ethiopia.

It suffered from severe drought

in the northern parts
of the country.

The droughts
inflicted two consecutive

poor crop
and pasture seasons.

18 million people needed
food assistance in 2016.

This was the greatest need
the country had faced

since the 1984 famine,

which sparked the Live Aid
campaign run by Bob Geldof.

In contrast,
the south of the country

suffered torrential rains
and flash floods.

The floods arrived after
nearly 18 months of drought

that left communities
ill prepared to cope.

The long drought
reduced the ground's ability

to absorb water,
which exacerbated the floods.

When you have
two different types

of disasters
in one country,

that provides a particular
problem for aid,

because when you have a heavy
drought and a heavy flood,

the crops will fail everywhere,
but for different reasons.

The myriad of impacts,
the unpredictability,

but also the scale of El Niño,

presents international
organizations

with almost
unprecedented challenges.

This can be seen vividly
in the range of devastation

the 2015-16 El Niño wreaked
on the Pacific Islands.

It threatened
their very existence.

Almost two million tourists

visited the multitude
of islands in 2015,

but the Pacific Islands
weren't to be spared.

Their small populations,

remoteness,
few resources,

and dependency on foreign aid
only made them more vulnerable.

The problems associated
with extreme events

are made much worse
on small island states

because they tend to be
remote,

they tend to be
relatively poor,

and they don't have easy lines
of communication for food,

aid money,
shelter, et cetera,

to come into those countries.

For example, a small island

developing state
in the Pacific,

it may be half a day's journey
from the nearest rich country,

which is probably Australia
or maybe Hawaii,

which are themselves
relatively sparsely populated,

and aid workers will have
to travel to themselves.

And of course,

if harbor, or more importantly,
an airfield is damaged

then the planes can't land,
and the aid can't come in.

Wave after wave of cyclones
swept across the islands:

Pam, Maysak, Raquel.

Pam was the strongest storm

to ever strike
the South Pacific.

On Vanuatu,
entire villages were destroyed.

Eleven people were killed

and thousands were left
without shelter.

There was to be no respite.

Scarcely had the cyclones left

then the islands
were hit by drought.

States of emergency
were declared in Palau,

the Marshall Islands,

and the Federated States
of Micronesia.

Koror, Palau's capital,

recorded its lowest rainfall
in 65 years.

People had to ration water
to survive.

Wells became brackish
or ran dry.

Staple foods such as
breadfruit and bananas

shriveled on trees.

Micronesia's islands
and atolls

are not always the paradises
they can seem from photographs.

They can quickly run out
of drinking water.

Relief agencies struggled to
bring water to remote atolls,

a day's boat ride
from the main islands.

But El Niño damaged the
Pacific Islanders' livelihoods

in other ways.

The warmer water
has less oxygen.

Less mixing of water

leads to reduced production of
microscopic plants and animals

needed for tuna.

Particularly skipjack
and yellowfin.

The warmer water
in the western Pacific

shifted the tuna's
spawning grounds

to the central and eastern

equatorial regions
of the Pacific.

This dramatically reduced
the catches

for the island fishermen,

having a severe
economic impact.

Despite the country's obsession
with talking about the weather,

dramatic meteorological events

have been relatively rare
in the UK.

However, in 2015,
all this changed.

The UK is used to floods.
We have regular floods.

Almost every year
there is a major flood,

but in 2015,
the flooding was extreme.

I don't think anybody was
prepared for the extreme flood

that Storm Desmond
especially brought with it.

Humid air,

borne by strong
southwesterly winds,

dumped huge quantities of rain
over Northern Ireland,

Wales, northwest England,
and Scotland.

It began with Storm Desmond,

which dropped over 33
centimeters of rain on Cumbria

between the 4th
and the 5th of December.

It broke the national record
for rainfall in a day.

Sitting in the house,
I saw the water

coming up under the tiles.
You know.

It's quite frightening.

Horrendous, it's-it's mad.

It's terrible,
I don't know what to do.

Carlisle and other areas
of Cumbria were flooded.

More than 5000 homes
were affected in Cumbria

and Lancashire alone.

We need to make sure they get
all the support they need,

get the insurance claim
paid quickly,

get them the alternative
accommodation,

make sure the council
picks up the furniture

and the things they've had
to throw out of their houses.

And then try and get them back
in as soon as possible.

The average person is out
of their home for nine months

after a flood.
And after Storm Desmond,

many people in Carlisle

were not back in their homes
for two years.

People suffer with post-
traumatic stress disorder.

They're anxious
every time it rains.

It's a very deeply
personal experience.

Storm Eva followed Desmond.

Eva brought with her
more heavy rain,

which fell on
the already saturated earth.

People don't realize

that just a few inches
of water can float a car,

that a few inches of water
can knock you off your feet,

that you can fall down
manhole covers

that have been lifted
by the sheer volume of water,

that little streams
become torrents

and people haven't woken up

to smell the floodwater,
as it were.

And they don't grasp
just how dangerous

flooding can be
and how it can kill people.

It can and it does.

The ensuing floods

engulfed thousands of homes
and businesses,

swelling rivers
and breaking bridges.

River levels stayed high

and over 70 flood warnings
were issued

as the rain continued
to fall remorselessly.

On the 22nd of December,

communities in Cumbria
were flooded again.

For some, it was the third time
in under a month.

It's not Christmas to us
in Carlisle,

I don't think at the moment.

You don't feel very festive
when you've been through this.

We did all the topographical
surveys.

We worked all
the measurements out,

built a flood bund
last year and the year before,

installed pumps this year,

nearly finished paying for it,

but unfortunately, I'm told
there is a foot of water

in church this morning.

On Christmas Day,

more than 100 flood alerts
and warnings were issued,

as Storm Eva
battered the country.

There was to be no respite.

Once again, northern England
was the worst hit.

On Boxing Day,

people in West Yorkshire
and Lancashire

had to be evacuated
as flooding hit Leeds,

York and greater Manchester.

There are no words
that describe the devastation.

Roads were washed away.

Bridges were washed away.

Flood defenses
were overtopped and breached.

People's homes
were flooded to the ceiling

and businesses were annihilated.

Among the rivers
to burst its banks

was the River Ouse in York,

where 500 homes were flooded

and the Army
was called in to help.

I'm now left feeling really,
really angry.

I've got two little boys
who are out of their houses.

We don't know where
we're going to be living.

It's going to take months
and months

and months for this
to be restored.

The inconvenience
is indescribable.

Individuals suffered hugely.

Having been flooded myself,

I know how awful
being flooded is.

And I don't think anybody
can convey

the true awfulness
of being flooded.

But people's houses,

because of the sheer volume
of water,

will have found
that their furniture

wasn't where it was
when they left it.

It will have been covered
with a thick,

horrible smelling,
sludgy brown filth

and going into their homes--

The smell--
You cannot describe the smell.

It really gets you
at the back of your throat,

and no filming
will ever tell you

how truly awful
the smell will be.

Many communities
were still trying to recover

from the aftermath
of Storm Desmond.

Hundreds of people were forced
to evacuate their homes,

as rivers burst their banks
in the Cumbrian towns

of Appleby,
Keswick and Kendal.

Scotland, northern England

and Ireland
were all overwhelmed.

Flood defenses
failed to cope with the rain

cascading through the rivers.

If these defenses
had not been in place,

you're potentially looking at as
much as two meters more water.

That's six feet more water
going into people's houses.

So the tens of millions
that have been spent on defenses

has been really valuable.

Tens of thousands of properties
were also left without power,

dozens of schools were closed,

around 40 bridges
were either damaged or shut,

and rail links
were severely disrupted.

It's not a quick fix.

It takes a long time
to recover.

And in fact, some people haven't
recovered from it to this day.

It truly is life-changing.

The Army had to be drafted in
to help with the evacuations.

That means supporting
the work of the police,

the environment agency,

and all the other people
that are now deployed out here.

And we're working
alongside them

and will continue to do so
for as long as it takes.

Even the Royal National
Lifeboat Institution

was called upon to help.

So when you've got extreme
floods like that,

and you've got
hard engineered defenses

overtopped and-and breached,

and you see trees
coming down the hillsides

and loads and loads of rocks,

it's very difficult to actually
stop that from happening.

In Tadcaster
in north Yorkshire,

the town's bridge collapsed.

It split the town in two.

Residents had to take
a 16-kilometer detour

to get from one side
to the other.

The floods made giving help
particularly hard

as they swept through
the town's only medical center.

In their descriptions
of the event,

residents compared the town
to a warzone.

The Royal Air Force
used helicopters

to drop huge sandbags

into the breach
of the River Douglas.

The UK's meteorological office

analyzed the reasons
for the December floods.

They confirmed that El Niño

had contributed to
a persistent weather pattern,

which led to unusually warm,
moist air reaching the UK.

I don't think people are aware
that a disaster as such

may happen
because of climate change

and because of effects
like El Niño.

It's an unusual concept
to get our heads around.

I don't think people
have the first clue

that something that happens
in the Pacific Ocean,

where the Pacific Ocean
is heating up,

can possibly bring so much rain
to our country.

It's something that we've
got to become aware

that may happen more
in the future.

December 2015

turned out to be not just
the wettest December on record,

but also the wettest month
ever in the UK.

The UK is still grappling
with the problems of storms

and the floods they bring,

even though changes have
been made to infrastructures

and how the country responds.

The sheer scale
of the challenge

has led the government
to change its approach

from one of protection

and building
higher flood defenses,

to improving communities'
resilience and infrastructure

to when floods do happen.

Organizations like local wildlife trusts

are advising on better
landscape management

such as installing
flood storage areas,

planting trees, and getting
farmers to plow across slopes

to slow the flow of water.

In one of the worst
hit villages,

Glenridding in Cumbria,

thousands of tons of gravel
were removed from the river,

walls were raised,
and drains improved

to reduce the risk.

The floods themselves actually
cost about £1.6 billion,

and that's
government statistics.

But obviously the-- A lot
of people weren't insured,

so they weren't able to apply
for flood insurance.

The 2015-16 El Niño

was as remarkable for its reach

as for its range
of extreme weather impacts.

Countries across five continents

called states of emergency.

It brings extremes
from both ends of the spectrum,

sometimes both in the same place.

A clear example of this

is the 2015-16 winter in Canada
and the United States.

December 2015

set records
as the mildest in 120 years.

Some places
in the Midwest and East

were as much as nine degrees
Celsius warmer than normal.

Then,
as the new year arrived,

so did the cold.

The east coast
and southern United States

were plunged into well below
average temperatures,

and many saw snow.

But this was only the beginning
of what was to come.

The coastline was soon
to be hit by a giant blizzard.

Between the 20th
and the 22nd of January 2016,

governors of 11 states and
the mayor of Washington, D.C.

declared states of emergency

in anticipation of heavy
snowfall and strong winds.

On Saturday,
the 23rd of January,

Blizzard Jonas hit.

New York City was paralyzed.

The blizzard dropped
69 centimeters of snow

on Central Park.

This was the most snow
the park had seen

since records began in 1869.

Governor Andrew Cuomo
issued a travel ban

for New York City
and Long Island roads

on Saturday afternoon.

Mayor de Blasio
said that drivers

who violated the ban
could be arrested.

Snow fell
even in southern states

that are rarely associated
with white winters.

Georgia and South Carolina

reported as much as
19 centimeters of snow cover.

Louisiana and Mississippi

both reported over
5 centimeters in some areas,

and one town in Alabama
had as much as 9 centimeters.

West Virginia
received the most snow,

getting a whopping
106 centimeters

in the town of Glengary.

Jonas battered the country

with 126 kilometer
per hour gusts,

and sustained winds of up
to 91 kilometers per hour.

By Monday, the 25th of January,

the storm was still
going strong.

Schools all over
the east coast were closed,

as were federal offices
in Washington, D.C.

People were bunkered up
in their homes,

unable to leave.

Hundreds of thousands of people
lost electricity

during the storm.

When the winds finally subsided
and the snow let up,

over 100 million people
had been affected by Jonas.

As many as 13,000 flights
had to be canceled.

And, worst of all,

at least 48 people
had been killed.

Storm Jonas was what is called
a Nor'easter,

a cyclonic storm named after
its northeastern winds.

While Nor'easters can occur
at any time of year,

they are most common
in the winter months.

One notable difference between
a rainstorm and a snowstorm,

is that snow has a tendency
to stick around.

Water runs off,
dries up,

and is absorbed by the ground,

but, unless temperatures
rise above freezing,

snow stays
right where it lands.

This means a lot of work
for cities and communities

to clear the snow off roads,

roofs and vehicles.

It can take days
for even a well-prepared city

to recover use of all roads.

For those not used to snowfall,
the situation is much worse.

Uncharacteristically,

in the 2015-16 El Niño,

Peru wasn't affected.

The year after,
however,

serious rains and floods
struck the country.

Between January
and February 2017,

a region of northern Peru
and Ecuador,

which is a desert region,

received considerable amounts
of rain.

Rivers burst their banks.

Houses were under
a meter or sometimes...

sometimes two meters of water.

This resulted in considerable
destruction to infrastructure

and property and fatalities.

And this is
particularly difficult

for the region to deal with

when you consider
that it's a region

that often receives just a few
millimeters of rainfall

or no rainfall at ll.

And suddenly, it received

several tens of centimeters
of rainfall

in a very short period
of time.

The wet weather was caused

by a warming of the ocean

off the coast of Peru
and Ecuador.

The locals referred to it
as an El Niño.

But the rest of the world
remained unaffected.

This illustrates just
how limited our understanding

of the El Niño Southern
Oscillation system is.

Scientists across the world
can't always agree

on what is and what isn't
an El Niño.

Some of Peru's poorest
were most severely hit.

Many had set up home
in gulches and canyons

that opened from the mountains
onto the coast.

Dry for years,

they suddenly turned
into raging torrents,

engulfing and sweeping away
whole shanty towns.

The rains also washed rubbish,

chemicals and metals from towns,

mines and farms
into the Pacific Ocean.

Warm coastal waters drove out
schools of Peruvian anchovies,

depriving birds
of their main food supply

and forcing them
to hunt elsewhere.

Two thirds
of the Guanay cormorants

on the south-central coast
abandoned their nests.

On top of the effect
on the ecosystem,

losing the birds
reduced the guano,

which is still mined
in the area.

Tourists in Machu Picchu
were stranded by mudslides

and had to be airlifted
to safety.

Peru's 2017 El Niño event

was one of the most costly
disasters to hit Peru

since 1997-98.

It underlined again
how unpredictable

and ill-prepared we were to
deal with its chaotic effects.

The recovery from that
can take a very long time,

particularly in relation
to investments,

in rebuilding infrastructure,

so roads and bridges and so on,

to get the money
to be able to recover

and rebuild that infrastructure

can take a poor country
an extremely long time.

If El Niño's erratic nature

was not difficult enough
to deal with,

the phenomenon
has a twin sister,

La Niña.

La Niña is the opposite,

the cold phase of the El Niño
Southern Oscillation.

It happens when sea surface
temperatures

in the central Pacific Ocean
fall below normal.

In the United States,

a La Niña winter means more
rain in the Pacific Northwest,

short spells of below-average
temperatures in the Northeast,

and generally dry
and mild conditions

for the southern states.

Whilst an El Niño can spark

streams of moisture
into California,

a La Niña winter stops storms

from delivering snow and rain
to the region,

leading to droughts.

Western Canada
and the Northwest

suffer the most from storms
during a La Niña winter.

La Niña makes winters
in the Northeast

extremely unpredictable.

They can range from colder and
drier to milder and stormier.

La Niña also creates perfect
conditions for cyclone systems

over the Atlantic.

Lasting from 10 to 12 months,

La Niña does not
always develop

immediately after an El Niño.

However, evidence suggests
that strong El Niños

are more likely
to turn into La Niñas.

Quite regularly,
you will find that an area

that was affected
by an El Niño

is then immediately affected by
the La Niña that comes after it.

Having an El Niño and La Niña
year in quick succession

can be devastating
for a country,

particularly countries that are
poorly resourced,

poorer countries.

Alarmingly, La Niña years

have clearly shown
greater average annual losses

in comparison to El Niño
and neutral phases.

Much of the increase in losses
during a La Niña year

is due to tropical cyclones
making landfall

more frequently in
the Atlantic Ocean basin

and increased flooding
across the Asia Pacific.

It is believed there have now
been three "super El Niños"

in just over three decades,

suggesting these "super El Niños"

might start occurring
once every 10 years,

instead of once every 20.

El Niño,
and its twin sister, La Niña,

are a strong reminder

to communities vulnerable
to changing weather patterns.

They are going to need
longer-term help adapting.

The UN has warned
that humanitarian disasters

are to be expected
with climate change.

We can see how the effects
of El Niño

can combine
with climate change

most starkly
in the Pacific Islands.

Although the relationship
between El Niño and drought

in the region is well known,

it remains unclear
how global warming might alter

the El Niño phenomenon
in the future.

The islands' residents
are deeply anxious.

Rising sea levels
are already swallowing

the little land
they have.

They also threaten
water supplies,

as the waves that can make
groundwater saline

become more frequent.

It is rainfall's variability,

not average rains,

that mainly drive
drought here.

And the main source
of variability is El Niño.

The study of the El Niño
Southern Oscillation

is a relatively
new field of research.

We are still struggling to
understand its unpredictability

and how we can mitigate
its effects.

Our forecasting
is based on data

gathered over a quarter
of a century ago.

More recent research
and satellite data

suggests that the impact
of El Niño Southern Oscillation

is much wider
than originally believed.

Europe, Africa, Asia
and North America

are all likely to have
been affected

in ways we hadn't realized:

air temperatures, rains,

and in North
and South America,

significant impacts across
a larger area than we thought.

Factors like climate change
are only likely to increase

El Niño Southern Oscillation's
unpredictability.

El Niño and La Niña

are challenging governments
and international organizations

to consider and build
this unpredictability

into their planning.

We still grapple to understand
the full impact

of El Niño's
Southern Oscillation.

The only certainty seems to be
the misery and devastation

brought in its wake.