Original subtitles

- [Narrator] 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.

(water rushing)

(dramatic music)

(somber music)

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.

(somber music)

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.

(somber music)

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.

(somber music)

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.

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- [Narrator] 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.

- [Narrator] 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.

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- [Narrator] 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.

- [Narrator] 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.

- [Narrator] 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.

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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.

- [Eric] 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.

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- [Narrator] 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.

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- [Narrator] 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.

(ethereal music)

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.

(ethereal music)

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.

- [Narrator] 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.

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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.

(ethereal music)

ICESat-2, with an advanced laser altimeter system,

is continuing the work of its predecessor.

(ethereal music)

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.

(dramatic music)

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.

(dramatic music)

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.

- [Narrator] So NASA scientists cross the Antarctic,

taking altitude and radar depth measurements

to help calibrate ICESat-2's instruments.

- [Tom] 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.

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- [Narrator] 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.

- [Narrator] 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.

- [Narrator] This animation shows how different

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

where the food and freshwater will come from.

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