All language subtitles for 8513567DAD5B069AEDF5E8F77959C9CB_eng

The cryosphere
is the ice mass of our planet.

The ice sheets, permafrost
and water ice of the poles.

A moderator of ocean and
atmospheric temperatures,

a sun reflector, the
cryosphere is an integral part

of this planet's cooling system.

Climate change is shrinking the icecaps,

and it's a runaway effect.

Our world is warming.

The oceans are rising, and we need

to do something about it.

Of all the freshwater on Earth,

99% is stored in ice sheets,

the large frozen masses
that form over land.

As climate changes, melting ice sheets

can contribute to rising sea levels,

which can place vulnerable cities

around the world in jeopardy.

From the South Pole to Greenland,

from Alaska's glaciers to Svalbard,

NASA's Operation Icebridge covered

the icy regions of our planet in 2017,

with a record seven
separate field campaigns.

The mission of Icebridge, NASA's longest

running airborne science
program monitoring polar ice,

is to collect data on changing ice sheets,

glaciers and sea ice,
and maintain continuity

of measurements between
ICESat's satellite mission.

World-renowned leading climate scientist

and astronaut Dr. Piers Sellers

was director of the Earth
Science Division at NASA-Goddard.

Having seen Earth from space
on three shuttle flights

and six EVAs, Dr. Sellers
was deeply concerned

for the future of our climate.

- Now, Icebridge is probably
one of the most important

field campaigns we have running right now.

The world is warming,
and it's warming faster

in the north, around the
Arctic, than anywhere else,

by a factor of two and a half.

It's two and a half times
increase in warming here

compared to the global average.

So this is where it's all happening.

And as a consequence,
the ice is melting fast.

It's melting on the Arctic Ocean,

and the ice mass on top of Greenland

is melting and falling into the Atlantic.

So we're mapping that using aircraft

and satellites where we can.

And of course we've got
people on the ground,

checking against these data as well.

So this is ground zero for global warming.

We're doing a lot of work here,

we put a lot of effort into it.

And I think it's paying off

in terms of improved understanding.

Operation
Icebridge began in 2009,

and continues to fly
aircraft through the region

with advanced sensing equipment

and coordinated land
traverses by scientists

to ensure accuracy of satellite data.

Now in conjunction with
the European Space Agency,

they coordinate and share
data with additional

satellite assets which fly
identical science instruments.

Just why are the icecaps melting?

Because of the so-called greenhouse gases,

carbon dioxide, methane, nitrous oxide,

and fluorinated gases in the atmosphere.

Together, they heat up the
atmosphere by trapping energy.

While CO2 has always been part
of the atmospheric makeup,

it has changed since the
Industrial Revolution.

- In the preindustrial
age, the CO2 response

to temperature was that the temperature

would go up and CO2 would go up.

And so if the temperature
went down, CO2 would go down.

And the reason for that is
when the temperature went up,

the whole biosphere
revved up and emitted CO2.

And we had more CO2 in the atmosphere.

So we understand that process.

The problem for the science community

is in the postindustrial age,

the CO2 rises preceding
the temperature rise.

So two different things happened.

One preindustrial, where
temperature was driving the CO2.

Postindustrial, where the
CO2 is driving temperature.

Which means a completely
different physical,

biological process is going on.

And we don't understand
what the consequence

of that change is, it
is a fundamental change

to how the earth works, and how earth's

radiation balance works.

And so since we don't understand
that, we're very concerned.

Because we don't see any restraining force

on continued increase in temperature

due to continued increase in CO2.

And that's a problem.

Warmth
tipped the scales again,

with the hottest October on record.

But also the fourth hottest
year to date for the globe,

according to a fresh
analysis by scientists

at NOAH's National Center for
Environmental Information.

Generating longterm datasets is extremely

important when studying climate.

So to maintain continuity,
a new generation

of Earth observation
satellites are coming online.

ESA have deployed Aeolus,
METOP Three, Sentinel C,

and NASA have launched ICESat-2, the JSSC,

and the Follow-On GRACE missions.

All of these satellites
have one instrument

in common that measures altitude.

- A radar altimeter is
a beautiful instrument

because it measures almost
everything we need on the planet.

It measures the height of the sea,

the height of the icecaps, but
also we can use it to measure

the heights of lakes and rivers,

even derive river discharge.

METOP-C, the
third in the METOP program,

carries no fewer than 13
observational instruments.

Some are identical to
NOAH's suite of satellites.

- We have 10 instruments aboard METOP,

it was a very large platform.

And these instruments are also provided

by different organizations.

We have a set of instruments
provided by NOAH-NASA.

We have instruments provided by CNSA.

We have brought instruments
that are procured by ESA,

and some other instruments
which are procured by EUMETSAT.

- So METOP-C is the last
satellite of a cooperation program

that we had with NOAH in the United States

as part of what we called the
Initial Joint Product System.

So in 1998, EUMETSAT and NOAH signed

this cooperation agreement,
where three European satellites,

or three METOP satellites were

corresponding to three US satellites.

And for these satellites,
we share instruments

so that the user gets
information from both satellites,

the same types of information.

So we tried to create synergies
between the US and Europe,

more benefits to our user.

- We didn't expect that
we'd be able to measure

sea level to just a few
millimeters every 10 days.

And having such accurate
measurements for 25 years

that it's monitored sea level rise.

And even perhaps detect an acceleration

in the sea level record.

And that was something that
wasn't envisioned 25 years ago.

But as the technology has
gotten more and more accurate,

we've been able to make more and more

accurate measurements of sea level.

And so we can be even more
confident in our results.

Combined with, we have
other observing systems

other than altimetry, we
have a gravity mission,

called GRACE, where every
month we weigh the ocean.

And we have robots that
float throughout the sea,

about 3,000 to 4,000
that take the temperature

of the ocean every few days.

So when we add up the results we get

from the gravity mission, where we weigh,

and where the ARGO floats,
where we take the temperature,

we get almost exactly the same answers

that we'll get from the radar altimeters,

to within a few millimeters.

So we're very confident in our results

that we're seeing 25
years of sea level rise

of about three millimeters per year.

Which doesn't sound like
a lot, but as we see it

starting to increase year after year,

we know that acceleration
will be very devastating

for coastal communities
all over the world.

AEOLUS, ESA's
newest Earth explorer satellite,

with which the agency
will measure wind profiles

from space with laser technology.

- At the moment, we have
a very poor understanding

of how the wind is around the globe.

And we need more knowledge about that.

But that's the information
you need to start.

You need to have a picture
of how is the weather now

to be able to predict how is
the weather in the future.

- AEOLUS is a relatively short mission

to demonstrate the
potential of the Doppler

wind light air in space.

And once we can demonstrate
that actually it's made a decent

impact on the numerical
weather prediction forecast,

then hopefully we can have an
operational follow-on mission,

or maybe several satellites in tandem,

rather than one just satellite.

It's not just wind information, actually,

you need to also known
temperature information,

pressure and humidity information.

But the winds are a key
component of that information

that you need to know right now

to work out the weather in the future.

Sentinel-3A
was launched in 2016,

and 3B in 2018.

Both satellites primarily
focus on our oceans.

They measure the
temperature, color and height

of the sea surface, as
well as sea ice thickness.

These measurements are
needed to study changes

in sea level, marine pollution
and biological productivity.

Sentinel-3A has already
yielded interesting results.

- The Sentinel-3 mission was actually

quite a versatile mission
in the sense that it serves

a large variety of different
Copernicus services.

So we're not just working with

the Marine Environment Service,

we're also working with the
land, with the atmosphere,

and with the Climate Service.

There's a large variety of data
that we can actually supply.

The Marine Service is probably the most

developed for the moment.

It's already using data over the ocean,

in particular the ocean color data,

which tells us something
about the marine ecosystem,

about the health of the
sea, and can basically

also predict something
like harmful alga blooms.

Snow cover gives us an idea
about the snow water extent.

And so basically, that
gives us an idea of,

when this melts, for
example, where we go in terms

of flat forecasting runoff models.

So for hydrological applications,

but also for weather
forecasting, for example.

- Sentinel-3 Mission is supposed

to last until 2040 at least.

So A and now B will be in space soon.

The C and D models, which
are replicas of this one,

are under manufacturing
now, and will be completed

by the end of the decade.

And they are expected to be
launching in 2023-24 time frame

to cover basically the
Sentinel-3 mission until 2030.

That's why we want to
have continuous measurements.

So we have planned with the
next series of JASON missions.

JASON CS or Sentinel-6
that will have at least

10 more years of measurements.

Because we need to keep monitoring

the sea level as it accelerates.

With this
long-range forecasting,

the acceleration of global
warming can be monitored,

and better predictive models developed.

- Yes, that's why, by having
all three measurements,

that helps us understand the cause.

That we can see from
GRACE a measure of which

continents the water is coming from,

that Greenland and Antarctica are melting.

And some glaciers are also melting.

And we can also see, as the temperature

of the globe increases,
we can watch the water

in the ocean actually expand
for not more and more heat.

Scientists on the
ground continue to innovate

ways to improve satellite data accuracy.

Surfing for science may seem far-fetched.

Yet, that is exactly how Dr. Bob Brewin

of the Plymouth Marine
Laboratory is pioneering

a new technique in satellite oceanography.

By equipping his surfboard with
a device called a SmartFin,

Bob can measure sea surface temperature

and motion of coastal
waters with his smartphone.

Later, Bob can use the
SmartFin data he has gathered

to better interpret
Sentinel-3 satellite data.

The Sentinels are part of
the Copernicus program.

Using the three instruments on board,

the satellites gather
information on ocean color,

water quality, changes in
sea level, and most important

for Bob's research, sea
surface temperature.

- With over 40 years of
thermal radiometry we have now

from our satellite platforms,
we can begin to get

a really good understanding of how

temperature's changing in
the near shore environment.

And temperature is a critical
component of our oceans.

It controls the biology,
through changes in growth rates

and reproduction, it controls
the physical environment,

together with salinity, it controls

the density of the ocean,
how coastal currents move,

and it's also a fundamental
component of marine chemistry.

The reaction rates of many chemicals

are temperature-dependent.

The gases that move from
the atmosphere to the ocean

are temperature-dependent.

In situ data
gathered by scientists

like Bob is extremely important

because it complements
and helps to verify data

provided by the Sentinel satellites.

For example, the temperature
of coastal waters

is difficult to measure from space,

for they have very high
levels of marine biodiversity.

So scientists find new and
ingenious ways of increasing

the number of in situ
measurements in these waters.

With the SmartFin, for instance,

surfers and other water sport enthusiasts

can gather data while
enjoying their hobby.

Meanwhile, NASA has dispatched
two new satellite missions

to observe the most critically
changing regions, the poles.

NASA, and the German Research
Center for Geosciences, GFZ,

has launched GRACE-FO,
continuing the revolutionary

gravity measurements of
its predecessor, GRACE.

ICESat-2, with an advanced
laser altimeter system,

is continuing the work of its predecessor.

This new technology will
help study ice sheets,

but also sea ice, glaciers,
permafrost and snow cover.

Collectively known as the
cryosphere, these frozen zones

help sustain stable
conditions for life on earth.

- ICESat-2 is NASA's latest technology

to measure the elevation or
the height of ice sheets.

And by repeating those
measurements through time,

we can measure how ice
sheets are changing.

It'll also allow us to
measure the height of sea ice,

which is a way to understand
the thickness of that sea ice.

And so it's really a huge advance forward

in both our precision of elevation

change measurements, as well as coverage.

Each of those six beams gives us much

more data than we've ever had before.

ICESat-2 was designed and built here

at NASA's Goddard Space Flight Center,

and it does take advantage of many

of the latest advances in that technology.

It's really an excellent tool for studying

changes in ice sheets and in sea ice.

For sea ice, it's really critical.

It plays a first order effect

in weather patterns around the world.

Sea ice in the Arctic Ocean regulates

the exchange of heat and water vapor

between the ocean and the atmosphere.

And as sea ice gets thinner or thicker,

it either allows more or less

of that heat exchange to happen.

For ice sheets, as that ice
is lost back to the ocean,

it directly goes into sea level rise,

which of course impacts folks worldwide.

So NASA
scientists cross the Antarctic,

taking altitude and
radar depth measurements

to help calibrate ICESat-2's instruments.

One of the other
experiments we were doing

is leaving out what we
call corner cube reflectors

to get an assessment of
the pointing of ICESat-2.

When we make an elevation measurement,

how are we sure it's in the right place?

So in this picture, where
you can see a bamboo pole

with a little white cap on the end of it.

And embedded in that cap,
a little piece of glass

about as big as your pinky
nail, and calibrated to return

green laser light from the satellite.

With the requisite
observation tools in place,

the next step is to interpret the data.

- Ice sheets are actually really dynamic,

and they flow under their own weight,

from the center of the ice sheet

out to the perimeter of the continent.

In the really cold regions, and way high

up on our ice sheets, we get
a lot of snow accumulation,

and over time, that
accumulation can build up.

If it stays cold enough
and that snow persists,

and then you get another year of snow

and another year of snow,
you can imagine the weight

of the snow on top of itself forces

some of the lower layers to compact.

We call that the firm densification

of the top layer of the ice sheets.

When we talk about the
health of our ice sheets,

we talk about the mass
balance of the ice sheet.

Basically that means
coming in is in balance

with all the terms of
water or ice going out.

The health of the ice sheets

depends on a balance of these
terms of input and output.

But the interaction of the atmosphere,

ocean currents and temperatures
can force the ice sheets

out of this equilibrium.

- At a big scale, the winds in Antarctica

are kind of spinning in a big clockwise

direction around the continent.

But you can imagine a big dome of ice

has very little obstruction like trees

or mountains kind of steering the winds.

Consequently, winds that
sort of are gravity-driven

and come down the continent can build up

speed really quickly, and again,

uninterrupted by any sort of disturbance.

And we call those catabatic winds.

And they have a major influence

on what happens at the
edge of the continent.

Around Antarctica,
there's a massive current

that we call the Antarctic
circumpolar current.

And it flows clockwise
around the continent.

Close to the continent, we also have

the Antarctic coastal current.

It stays really close to the coastline.

And it flows counterclockwise
around the continent.

In addition to these
continent scale currents,

we also have regional scale
currents, such as gyres.

Gyres are these parts of the oceans

that are sort of isolated,
because of topography,

or ocean bottom topography.

They're usually closed
currents that often circulate.

The gyres have a big role
in sea ice formation,

and also in currents that actually float

underneath our ice shelves.

You can imagine that around
the edge of the continent,

near those ice shelves,
warm water from the ocean

can intrude into that cavity

and contribute to basal melting.

The melting from warm ocean waters

of the bottoms of our ice shelves.

Calving in Antarctica is
a little bit sporadic,

and it's hard to actually model.

But some of the contributing factors

associated with calving
include those strong

catabatic winds pushing on
the edge of the ice sheet,

pushing on the edge of the ice shelf,

and calving large icebergs.

So we're measuring surface elevation,

and we can take that vertical measurement,

kind of integrate it
over a whole ice sheet

and get a volume change.

And then the real science
of ICESat-2 is taking

that volume change and
turning it into a mass change.

And from that, we can determine
how much ice is actually

turning into water in our
oceans and raising sea levels.

So the Greenland ice sheet is thinning.

And it's thinning variably, but
mostly along the coastlines.

It's thinning beyond our expectations.

And all of that thinning is taking place

upstream of where the
ice sheet is grounded.

Therefore, that is going
right into the ocean

and contributing to mean sea level rise.

- Since we launched ERS-1 in 1992

we have been working on the
radar altimeter time series,

and we have derived a 25 year long

time series of sea level rise.

Sea level rise is a major
indicator of climate change,

because it integrates
for instance the melt

of Greenland and Antarctica.

We have analyzed this series,

and we have analyzed the
error, which is under control.

And so the scientists are convinced

that now we have clearly on average

eight centimeters of sea level rise,

but we also have regional variation.

For instance, in the tropics,
it's three times that value.

And, what we have also
analyzed with the recent data

is in the last five years, sea
level has been accelerating.

So it's not three millimeters per year,

or 3.2 millimeters per year,

it's more like 5 millimeters per year.

We have provided this data
to people doing projections,

to scientists, climate change
scientists doing projections.

And they have modeled
the sea level in 2100,

which is expected to be two
meters higher than today.

This animation
shows how different

the globe will look by then,
and prompts us to consider

where the food and
freshwater will come from.