Greetings, caring viewers,
to today’s episode
of Planet Earth:
Our Loving Home,
the first of a two-part
series, focusing on
the deep interconnection
between our oceans
and the world’s climate.
The experts featured today
are Dr. Steve Rintoul,
an oceanographer
from Australia’s national
scientific research body,
the Commonwealth
Scientific and Industrial
Research Organisation
and Professor
Anders Levermann,
a senior researcher at
the Potsdam Institute of
Climate Impact Research
in Germany and
the lead author of
the Sea Level Change
chapter for the coming
5th Assessment Report
of the United Nations
Intergovernmental Panel
on Climate Change.
Oceans cover 71% of
the Earth’s surface,
contain approximately
97 % of the world’s water,
sustain a diverse array
of sea life and play
a vital role in regulating
our planet’s climate
in a multitude of ways –
including through
thermohaline circulation,
also known as the
Great Ocean Conveyor.
If you think about
the globe and what this
overturning circulation
really looks like, it’s
probably easiest to start
in the northern part of
the Atlantic (Ocean)
up near Greenland
and Iceland.
Water sinks
at the surface there and
flows southward through
the whole Atlantic basin,
until it reaches
the Southern Ocean.
And then
very strong currents
in the Southern Ocean
redistribute that water,
(and) carry it around
the globe, spinning
around Antarctica.
That water then passes
through the Indian
and Pacific Oceans,
ultimately returns to
the Southern Ocean and
gradually warms and
becomes lighter again.
And then (it) flows back
in, northward through
the Atlantic Basin in the
upper part of the ocean,
and that closes the loop.
The oceans help stabilize
Earth’s temperature
by absorbing heat,
with approximately
a thousand times greater
heat absorption capacity
than that
of the atmosphere.
The thermohaline
circulation transports
a lot of heat from
low latitudes
in the Atlantic (Ocean),
near the equator,
to high latitudes
near the North Pole
in the Atlantic (Ocean).
The entire climate system
is in tune with
this thermohaline
circulation operating.
The oceans influence
climate mostly because
they can store and
transport vast amounts of
heat and carbon dioxide.
So, the upper few meters
of the ocean, for example,
can store more heat than
the entire atmosphere.
So when we talk about
global warming over
the last 50 years,
what we’re really
talking about is
heating up of the ocean.
Because about 80 or 90%
of the extra heat
that’s been stored by
the Earth’s system
over the last 50 years
has gone into the oceans.
And so the oceans
influence climate and
it also means that
observations of the oceans
are an important way
for us to track
climate change because
that’s where the heat
is accumulating.
Scientists estimate that
the oceans currently
absorb a third to 40%
of the CO2 emitted
from human activity.
However recent research
by Dr. Jeffrey Park of
Yale University, USA’s
Institute for Biospheric
Studies concludes that
in recent decades
there has been
a reduction in capacity
because the oceans
are warming.
If the oceans did not
serve as a carbon sink,
atmospheric CO2 levels
would be much higher
than the current
392 parts per million,
perhaps reaching
a highly dangerous
500-600 parts per million.
The other important
aspect is that
the ocean stores lots of
carbon dioxide that
we’re emitting into
Earth’s atmosphere
by burning fossil fuels
and by clearing land.
About a third of that is
ending up in the ocean.
If the ocean removes
that carbon dioxide,
that tends to slow down
the rate of climate change.
They’re helping to
slow down or moderate
the rate of climate change
that would
otherwise occur if all the
carbon dioxide remained
in the atmosphere.
What would happen if
thermohaline circulation
substantially slowed
or even shut down
due to the effects
of climate change?
Professor Levermann
believes such an event
would produce huge
instability in the planet’s
climate system, such as
global sea levels rising
10 to 20 times faster
than the current rate.
If you put additional
fresh water into the
North Atlantic (Ocean)
by melting Greenland
or by having more
discharge from rivers,
from Siberian rivers,
which flows into
the Arctic, and then
eventually into the North
Atlantic (Ocean) or,
change in precipitation
patterns in the Atlantic
(Ocean) can freshen the
North Atlantic (Ocean)
so strongly that
there won’t be
any sinking of water
anymore,
that would disrupt this
thermohaline circulation,
and could make it stop.
If you shut it down
in climate models,
the temperature in the
North Atlantic (Ocean)
decreases by up to
eight degrees (Celsius).
That’s on top of
global warming.
It’s not a contradiction to
global warming, because
it’s just a re-organization
of heat.
So the Southern Oceans
get warmer, the entire
Southern Hemisphere
gets warmer, while
the North Atlantic
(Ocean) gets colder.
The problem is that this
would already influence
agriculture in Europe
quite significantly,
but of course,
also the ecosystems and
the Arctic sea ice cover.
But it’s because there’s
so much heat associated
with this thermohaline
circulation,
it’s going to disturb
the entire climate system.
And that means
two things: First,
global warming would
increase or
would accelerate slightly
in this period.
And there would be
less CO2 uptake, which
would further increase
global warming too.
Then the rain belt
in the tropics would shift.
At the moment,
the rain belt, which
follows the equator
quite nicely, is slightly
dislocated over the
Atlantic Basin because of
this heat transport to
the north, because
this rain belt doesn’t
really want to follow
the equator,
it wants to follow
the thermal equator,
the warmest place.
When we return, we’ll
continue examining our
oceans and their effect
on global climate.
Please stay tuned to
Supreme Master
Television.
Welcome back to today’s
Planet Earth:
Our Loving Home
on Supreme Master
Television where
we are focusing on
how the oceans affect
the world’s climate.
Recently scientists have
discovered a fast-moving,
deep ocean current
around Antarctica
that transports
massive volumes of
water annually and is
a major component of the
Great Ocean Conveyor.
An important part of this
overturning circulation
are these very strong,
deep currents that
we find mostly
on the western sides of
the ocean basins.
They’re pretty well
studied in the Atlantic
(Ocean), but we know
very little about them
in the Southern Ocean.
So, there’s a huge plateau,
a submarine mountain
range, which is
more than
2,000 kilometers long,
that sits in the
Indian Ocean sector of
the Southern Ocean.
On the flanks of that
we had some reasons to
expect there might be a
current there, but no one
had ever measured it.
So we really didn’t know
just how strong
the current was
and whether it was
an important part of the
overturning circulation
or not.
A few years ago,
in a joint experiment with
Japanese scientists and
Australian scientists,
we deployed some
instruments along
the flanks of this plateau
to measure the deep
ocean currents there.
What we found
were some surprises.
The first surprise was
that the ocean currents
were quite strong;
the average speed
over two years was
about 20 centimeters
per second at a depth
of 4,000 meters.
Twenty centimeters
per second doesn’t
sound very fast,
but for the deep ocean
it’s very unusual.
In fact they’re the
strongest, the quickest
deep currents that we’ve
measured in the ocean
at those depths.
It sits about 4,000 meters
below the sea surface and
runs along the sea floor.
But it extends for
thousands of meters up
through the water column.
So, it occupies a lot of
the depth of the ocean,
but it’s quite narrow.
It’s only about
50 kilometers across.
So we’ve used
those current speed
measurements,
and measurements of
temperature and salinity
of the water to calculate
how much water
is moving northward,
away from Antarctica, in
this deep current system.
We found that it’s about
10 million cubic meters
of water per second.
That’s
a pretty tough number
to get your head around.
If we add up the flow
of all the world’s rivers
combined we get about
one-million cubic meters
per second.
This deep river of
cold water flowing away
from Antarctica is about
10 times the size of
all the world’s rivers
combined.
So what that tells us is
that this is indeed an
important branch of this
overturning circulation
and it’s one aspect of
the ocean currents that
we need to understand
and be able to simulate
if we’re going to project
how climate might
change in the future.
Little research has been
done on the oceans of
the Southern Hemisphere
compared to those of
the Northern Hemisphere.
However, over the years,
measurements of
Southern Ocean currents
have been improved
through the use
of innovative
satellite systems.
So what’s changed
in the last few years is,
first of all, much better
satellite instruments.
We have satellites that
can now measure the
height of the sea surface
to within
a millimeter or two.
So we’re able to study
ocean currents from
space now in a way that
we couldn’t do before.
It works a little bit like
a speed gun that police
might use on the highway
to determine how fast
your car is moving.
It sends down a radar
pulse from the satellite,
it bounces off the surface
of the ocean and
returns to the satellite.
“Argo,”
a robotic instrument
that collects regular
information on the status
of ocean currents,
is a collaborative
international project
in which 23 countries
contribute floats
and many others help
in implementation.
It’s an instrument
that drifts with
the ocean currents at
a depth of one- or
two-thousand meters
below the sea surface.
It’s carried
by the ocean currents,
and every 10 days it
inflates a small balloon
that’s part of the instrument.
That changes
the buoyancy.
It makes the float
a little bit lighter
in the water column.
It rises through the ocean
from 2,000 meters
up to the surface.
And it measures
temperature, salinity and
sometimes oxygen levels
as it goes.
When it reaches
the surface, it can
transmit that data to us
by satellite and then
sinks back down again
and drifts
for another 10 days.
We now have more than
3,000 of these instruments
deployed throughout
the world’s oceans.
We sincerely thank you
Dr. Steven Rintoul
and Professor
Anders Levermann
for taking time from
your busy schedules
to speak with us
about the oceans and
their relation to our
planet’s climate system.
From your significant
research, it is apparent
that the functioning
of the Great Ocean
Conveyor is
highly important in
controlling how much
carbon and heat
our oceans can absorb
and thus plays
a very significant role in
determining the extent
of future climate change.
For more details
on the scientists featured
on today’s program,
please visit
the following websites:
Professor
Anders Levermann
www.PIK-Potsdam.de
Dr. Steven Rintoul
www.CSIRO.au
Eco-conscious viewers,
thank you for joining us
on today’s program.
Please join us again
next Wednesday
on Planet Earth:
Our Loving Home
for the final part of
this two-part series.
Coming up next is
Enlightening Entertainment,
after Noteworthy News.
May the guidance
of the Providence
always be with us.
Greetings, informed viewers,
to today’s episode
of Planet Earth:
Our Loving Home,
the conclusion of a two-part
series, focusing on
the deep interconnection
between our oceans
and the world’s climate.
Oceans cover 71% of
the Earth’s surface,
contain approximately
97 % of the world’s water,
sustain a diverse array
of sea life and play
a vital role in regulating
our planet’s climate
in a multitude of ways –
including through
thermohaline circulation,
also known as the
Great Ocean Conveyor
which absorbs
large quantities of heat
and carbon dioxide.
Last week in part one,
we saw the different ways
in which the oceans
stabilize the climate,
but the relationship
is not one way.
Today we’ll examine
how climate change
increases sea levels
and some of
the possible consequences
that our world faces
from this process.
The experts featured today
Dr. Claude
Hillaire-Marcel,
a Canadian geoscientist
from the University
of Quebec at Montreal,
Professor
Anders Levermann,
a senior researcher at
the Potsdam Institute of
Climate Impact Research
in Germany and
the lead author of
the Sea Level Change
chapter for the coming
5th Assessment Report
of the United Nations
Intergovernmental Panel
on Climate Change (IPCC)
and Dr. Ted Scambos,
senior research scientist
at The National Snow and
Ice Data Center (NSIDC)
at the University
of Colorado, USA.
The major drivers
of advancing sea levels
are the thermal expansion
of seawater and the melting
of ice caps and glaciers
due to global warming.
We’re disturbing
the climate system with
a temperature increase,
and the higher
the temperature increases,
the more disturbance
we introduce and therefore
the risk increases,
I would say.
Sea level can rise by
the expansion of water
when it gets warmer.
That’s the simple part.
We know the physics
and the big question is
only how deep
it’s mixed down in the sea,
so how many layers
are expanding, really.
So we have several
feedbacks which we are
unraveling now,
both the ice shelf
melting feedback,
and melting in
the Arctic sea ice, which
leads to a warmer ocean
and a change in climate
in the Arctic.
The acceleration
of glaciers
seems to be accelerated
by the presence
of a little bit of melting,
which leads
to further sea level rise.
We know we’re going
to be pushed in
this direction of a climate
that we have not seen
in several million years.
Many scientists point out
that the future
sea level rise estimates
made in the 2007
4th Assessment Report
of the Intergovernmental
Panel on Climate Change
were far too low,
with the revised forecasts
pointing to danger ahead
for low-lying areas.
In its last assessment,
this group used
several climate models,
but all these models failed
or were too conservative
to really predict
the evolution
of the recent few years
in terms of sea level rise.
The sea level is rising
faster than these models
predicted in terms of
the shrinking of
summer ice in the Arctic.
There is less ice
in the Arctic in summer
than these models predicted
for the last few years.
I’m one of the lead authors
of the next report
of the Intergovernmental
Panel on Climate Change
on this specific
sea level chapter.
There we will
have to try to make
a very thorough analysis
of the sea level.
The last IPCC report
was good
but the sea level was
a clear underestimation
of what we have to expect
in the future.
The reason I say this is
that the last IPCC report
said, in the next century
we’re going to get
20 centimeters
to 60 centimeters
in sea level rise globally.
Now, in the last century,
we had 15 to 20
centimeters already.
The 20 to 60
for the next century
came from
the different scenarios
that we could have,
the different
global warming paths
that we might be on.
In the period from
where the projection
started in 2000, until
the report was published
in 2007, we had already
underestimated
the observed sea level
by 40%.
If you do already
the first seven years
by 40% wrong,
it’s almost half wrong.
So, the reason was simply
that we didn’t have
enough proper models
for the great ice sheets in
Greenland and Antarctica.
These are the unknowns.
We will now pause
for a moment and
when we come back,
we’ll have more about how
the heating of our Earth
is causing
sea level changes.
Please stay tuned
to Supreme Master
Television.
Welcome back to today’s
Planet Earth:
Our Loving Home
on Supreme Master
Television
where we are examining
the important relationship
between the oceans
and our world’s climate.
During the past century,
the global
average sea level
rose at a rate of about
1.7 millimeters per year.
The current average is
3.1 millimeters per year.
With the warming
of the planet
and the melting glaciers
and ice sheets,
one forecast by a UK and
Finnish scientific team
pegs the average
global sea level
to advance by 0.8 meters
to 1.5 meters
by the end of the century.
Many major cities
around the world, such as
New York City, USA,
are at one meter or less
above sea level.
In the last ice age
we had 120 to 130 meters
less sea level compared
to the present day.
So, when you hear
that we had
15 to 20 centimeters
in the last century
of sea level change,
you get the feeling that
we are only talking about
centimeters all the time
and that sounds like
not so much. It is a lot.
The ice melt in Greenland
is important.
The Greenland ice sheet
is 3,000 meters thick.
To the sea level rising,
the most critical one
today is Greenland.
The last episode
with a warmer globe
than present was
about 125,000 years ago,
an interval which
geologists refer to
as the last interglacial.
During this interval
the Greenland ice sheet
was significantly reduced
because
there was drastically
different vegetation
in southern Greenland
than today.
So it means
that the southern part of
the ice sheet had probably
largely disappeared.
And there was still
a robust ice sheet,
but in the northern part
of the island.
And it is an interval when
the average sea level
was about four meters
above present. Okay.
Minimum. Okay.
Possibly more than
four meters but it's a very
conservative estimate.
So it means that we have
started now a process
leading to a fast melting
of part of this ice sheet,
of the Greenland ice sheet
due to global warming
that is potentially leading
to a higher sea level of
few meters above present.
In terms of how fast,
again, it’s very… you know
things accelerate.
So perhaps
a couple of years ago,
a few years ago
I would have said,
"Well, maybe
a few thousand years,"
to be prudent.
Ah, now,
it’s perhaps 2,000 years
to see a very fast rise
in sea level.
And well, it means
that’s, at our time scale,
that’s one generation
or two generations or
three generations, which
is our real concern now.
The rate
of sea level increases
may be fast enough
to lead to really critical
and difficult
to solve problems
in many countries
of the world. Ok.
Bangladesh for example
just to mention one.
The Antarctic is an
extremely sensitive area
with respect
to global warming.
A recent study from
the University of Toronto,
Canada found that if
a complete disintegration
of the Western Antarctic
Ice Sheet were to occur
due to climate change,
the Sheet’s sheer weight
could cause
Earth’s rotational axis
to shift by 500 meters.
The scientists also
concluded that
such an event would
cause an uneven global rise
in sea level with the
coastline of North America
seeing a six meter rise,
and the rest of the world
seeing about
a five meter rise.
In fact, the West Antarctic
Ice Sheet has collapsed
several times over
the last five-million years.
When they occurred
in the past,
that meant the collapse
of the West Antarctic
Ice Sheet and
three and a half meters of
sea level rise from there,
plus another
three and a half from the
East Antarctic Ice Sheet.
So there was
about seven meters
of sea level rise.
Greenland and Antarctica
each probably account
for about 25% of
the total sea level rise
and sea level rise rates
have been going up
since the last
20 or 30 years or so.
Prior to about again 1990,
the sea level rise rate was
something like between
one and two millimeters
per year.
Now the total
sea level rise rate is
between two and three
millimeters per year and
we’re just getting started
on this warming trend.
The problem is that
Greenland and Antarctica
have the ability
to contribute much, much
more ice to the ocean,
which would cause
the sea level rise rate
to increase very rapidly.
Warming of the oceans
will increase
as the pace of warming in
the atmosphere increases
but not at the rate
that Greenland and
Antarctica can increase
their contribution of ice
to the ocean.
So in the future, more
and more of sea level rise
will come from
the ice sheets relative
to the thermal expansion
of the oceans.
Which countries
will be most affected
by increasing sea levels?
Several island nations
such as
the Maldives, Kiribati
and Tuvalu are in danger
of soon disappearing
altogether.
The President
of the Maldives,
His Excellency
Mohamed Nasheed
is looking for places
to move his country’s
entire population
in anticipation
of such an event.
Professor Levermann’s
research has closely
examined this issue
in terms of consequences
for Europe
and North America.
What we found was
an increase mainly
along the American
and the European coasts.
The strongest increase
was around
the Greenland coast.
There are people living
there, so it's important,
the highly populated areas
up to Florida (USA),
or the entire US coast,
the same
for the European coast.
US researchers
recently did something
slightly different;
they projected
global warming
plus a weakening of the
thermohaline circulation.
They found the U.S. coast
was very strongly affected.
So these are
the main regions
that need to worry.
That's the East coast
of the U.S. and Canada
and potentially
the European coasts, too.
We sincerely thank the
respected Earth scientists
featured today for
their insightful research
on the relationship
between the oceans
and our global climate
and for helping us
better understand
increasing sea levels and
the serious consequences
for life on our planet.
For more details
on the scientists featured
on today’s program,
please visit
the following websites:
Dr. Claude Hillaire-Marcel
www.Professeurs.UQAM.ca
Professor
Anders Levermann
www.PIK-Potsdam.de
Dr. Ted Scambos
NSIDC.org
Eco-wise viewers,
thank you for joining us
on today’s Planet Earth:
Our Loving Home.
Coming up next is
Enlightening Entertainment
after Noteworthy News.
May we all live
sustainable lives
to protect the oceans
and curb climate change.
Mr. Laurent Imbault is
a noted Canadian actor
and comedian and
founder of GoodnessTV,
an Internet television station
that broadcasts
only good news.
Through online media,
Mr. Imbault seeks
to improve our world.
The idea is to create
a network of people
sharing ideas, sharing
know-how, knowledge,
experiences,
so that things can move
a lot faster than
they’re moving now.
So GoodnessTV
really wants to become
‘goodness network’
where people can
exchange all these ideas
and grow faster.
Watch the second
and final part of
"Laurent Imbault
and GoodnessTV:
Uplifting the World"
Sunday, August 8,
on Good People,
Good Works.