>> MICHELLE: Hello and welcome to
NASA Goddard Space Flight Center.
Today we're going to talk about
one of the most compelling issues of our day,
sea level rise.
And with me is Dr. Tom Wagner,
the Program Scientist for the cryosphere at NASA headquarters.
>> TOM WAGNER: And today, we're going to take you
right behind the frontlines of sea level rise research,
out into the field with the researchers,
and here's what we're going to be talking about
for the next hour.
♪[Music]♪
>> TOM WAGNER: So the big thing is this.
Around the world, sea level is rising.
It's going up by three millimeters a year.
In the last 20 years it's gone up by three inches.
And, we're trying to understand kind of why that is.
But more importantly, we're trying to project out,
you know, where it's going to be in the next hundred years.
Like it or not,
already the East Coast of the US is seeing flooding
from sea level rise.
It's things like the big storms
that hit New York and New Jersey, Katrina.
But even in places like the Kennedy Space Center,
we're seeing tremendous amounts of erosion.
They've gone as far as to make a map
of areas that they are going to lose.
The City of Miami is getting routine flooding.
Now, you might say,
"Well, you know, three inches in 20 years. what's the big deal?"
We can probably deal with what we've already seen, right?
But you know, the thing that we're worried about
is that as you project out a hundred years,
it could be more like three feet, four feet, five feet,
and the way that society responds to that,
the costs rise exponentially.
>> MICHELLE: And one of the things
we're going to talk a lot about today is ice,
and talk to us about why ice is so important
in the topic of sea level rise.
>> TOM WAGNER: Yeah. So in general,
the rise that we're seeing today comes from two places.
One, as the ocean warms up,
it expands just like hot air in a balloon.
But also, two, the big ice sheets,
the glaciers of Greenland and... of Greenland...
the glaciers of Canada and Alaska,
the big ice sheets of Greenland and Antarctica,
they are waking up and spitting ice into the ocean
and that's the other half of sea level rise.
>> MICHELLE: And so, we're going to be bringing in Josh Willis
from the Jet Propulsion Laboratory.
And then we also have Vena Chu
who is at the University of California, Berkeley.
And I believe that's Larry Smith
from the University of California, Los Angeles.
>> JOSH WILLIS: Well, sea level has been rising pretty steadily
in the last 23 years around the globe,
and we've been measuring this with Satellite Altimeters
with our colleagues in the French Space Agency, CNES,
ever since 1992.
And the net rate of sea level rise
is about three millimeters per year,
which works out to about an inch a decade.
And, it's interesting because the rise isn't equal everywhere.
In fact, in places like the West Coast of the United States,
sea level has actually been falling very slightly,
and this is because of the natural cycles in the ocean
and the way the oceans and winds can push heat around
and redistribute it across the planet.
So sea level rise is actually not all that level.
>> TOM WAGNER: Yeah, but Josh, like,
but... overwhelmingly, right?
The total amount of sea level rise that we've seen,
say, in the 28th century versus the last 20 years,
what's it like?
>> JOSH WILLIS: Sea levels have increased.
The rate of rise has increased incredibly
in the last hundred years or so.
In the early 1900s
we were looking at about one millimeter per year.
In the 1950s it was more like two millimeters per year,
and now it's three millimeters per year.
And, in fact, if you look back even farther,
the last 2,000 years
have had almost no sea level rise whatsoever.
So we've pushed the Earth into a brand-new regime
and sea level rise is now the norm.
>> TOM WAGNER: Can you tell us a little bit, though?
And I know Michelle was asking about this before we started.
How do we actually get to those numbers?
Like you were talking about,
how do we know what sea level rise was
in the 1800s or the 1700s?
I mean today, you've pointed out we have this radar altimeters
that measure the height of the ocean,
but what are the other ways we know?
>> JOSH WILLIS: Well, we've had tide gauge records
for 150 years,
in a few places, even longer.
But in the last 2,000 years
we've actually been keeping a record of sea level rise
in the sediments in places like North Carolina.
There's a salt marsh there
and it turns out that the land there is steadily sinking,
just very slightly.
And as the water creeps up the land,
it leaves behind a record
in the form of tiny little bugs and critters,
uh, that die and live in the sediment.
So, uh, people drilling sediment cores
have actually been able to reconstruct
a very accurate sea level record for the last 2,000 years.
And, what it shows is not much until the last 150,
and that's when sea level rise really took off
and we began to see the rates we have today.
>> MICHELLE: Now, one of the things
I think people aren't aware of
is just how many resources NASA has
to study what's changing on the Earth.
Uh, I think that right now
there are actually about 19 different space crafts
that are orbiting the Earth
taking readings from everything
about the oceans, the land, and the atmosphere.
What are some of the missions that you specifically work with
and... and what are some of the data that you take?
>> JOSH WILLIS: Well, the best mission of all those
is the Jason Missions, in my humble opinion,
because those are the ones that I work on.
But, uh, I think, uh there's...
as you say, there is a whole bunch of missions.
The Jason Missions
measures sea level directly from space,
uh, missions like GRACE
actually weigh the continents and the oceans.
>> MICHELLE: Yeah, that's really excellent stuff,
you know, and the GRACE Mission that you mentioned
is one of the things that I find really compelling
that, in fact, there's so much water
melting off these glaciers,
it's actually changing the gravity field of the Earth.
I mean, could you tell us a little bit about
how GRACE works and how that measurement is made?
>> JOSH WILLIS: Yeah, GRACE is really fun.
Uh, in fact, um, it's made of two satellites.
Uh, they are named Tom and Jerry
and they chase each other around,
and whenever the first one goes over something heavy,
the pull of gravity causes it to speed up just slightly.
And the two satellites actually measure
the distance between each other
and you can use that information to infer the mass
of the thing you're flying over.
>> TOM WAGNER: Hey, Josh! I got a question yesterday
from a reporter.
Can you just talk a little bit about,
okay, look, the radar altimetry, the record we get
and how we see things like tide gauge,
how do they work and how does that all come together?
>> JOSH WILLIS: Yeah, well, uh,
so the satellites that measure sea level are really amazing.
They're 800 miles up
and they can measure the level of the ocean
in a... in about a six-mile footprint
with an accuracy of just one inch or better.
>> JOSH WILLIS: So it's an incredibly accurate
piece of equipment.
Um it measures the entire planet once every ten days.
And by averaging all of that data together,
we can actually,
uh, get an estimate of the total level of the ocean,
the total volume of the ocean,
with an accuracy of about half a centimeter,
so it's really tiny.
And they're really incredibly, accurate at these missions.
In fact,
we've often compared them with tide gauges.
So in a few key locations,
we have tide gauges
that have been running for the entire 23-year long record
and they've allowed us to help, tie together
one satellite after another.
We've also been lucky enough to have each satellite survive
until the next one was launched.
So beginning with TOPEX/Poseidon in 1992,
uh, and then continuing with Jason-1 in 2001
and Jason-2 in 2008,
and we're hopeful to launch Jason-3
sometime in the next six months, something like that.
Uh, and so, we're really excited
about our record of sea level rise
because, uh, it's one of the most accurate means we have
for charting,
how humans are changing the overall climate,
on the planet.
>> JOSH WILLIS: Because if you think about it,
the Earth is two-thirds ocean.
>> TOM WAGNER: Great! Hey, thank you very much
and I know we're going to have you back later in the show.
But coming up next, Michelle,
I think we have a video?
>> MICHELLE: Well, yes. In fact,
we're going to be speaking to a scientist
that actually does research
sponsored by the NSF in Greenland.
So if we can roll the video about
Mike Bevis and his work, please!
>> MIKE BEVIS: Yeah, this is the...
this is the champion, uh, glacier of Greenland.
This is Jakobshavn,
so this is the one that's losing the most mass.
It's losing so much mass you can see it in space,
they can see gravity change.
The loss of the mass is causing gravity to change.
Yeah, we've got instruments all over the place
but this is going to be one of our most important ones.
There's the antenna, and it's bolted to the rock.
So this ice is the... is the weight
holding the elastic Earth down.
As that weight is released by the loss of ice,
the ground is rising, that antenna is rising.
>> UNIDENTIFIED SPEAKER: And you can measure that?
>> MIKE BEVIS: We can measure that.
That's recording data 24 hours a day,
year after year after year.
>> TOM WAGNER: Hey! So one of the other things too is,
how do we take this kind of measurement you've made here,
with literally a GPS device
out in the field banged into the rock?
How do you combine that with satellite information
to get a big picture?
>> MIKE BEVIS: All the satellite...
all the techniques have got the strengths and the weaknesses.
Uh so there is... for example,
GRACE is incredibly precise,
it can measure a tiny change in mass,
but it's not always sure what that mass is.
It could be the mass of the rock is changing
if you've got post-glacial rebound
or it could be the ice or some combination.
>> MIKE BEVIS: So in that case,
uh, you have to make a correction
for what the vertical movement of the ground is
so you're not spoofed by a rock change
rather than an ice change.
It turns out that correction
is about the same size as the answer.
So if you get the correction wrong,
you start to get errors in you answer.
So GPS can help with that
because this is going to sense both elastic rebound
and the slower viscous rebound.
And in general, you want to combine different instruments
so that each instrument is compensating with its strengths
for the weaknesses of the other instruments.
>> MICHELLE: And this is something
that I think most people don't think about,
the fact that the Earth, you know, solid land itself
is actually elastic,
but as the ice melts it's rebounding.
>> MIKE BEVIS: Yeah, like for example,
I first realized this, uh, in a big way
when we were looking at GPS stations
in the Central Amazon basin.
We noticed that these stations were going up and down
like 16 millimeters every year.
And then... and then we looked at
the height of the Amazon River
and we saw that as the river was going up
the ground was going down,
as the river went down the ground was going up.
It was just the weight of the water
deflecting the surface downwards.
>> TOM WAGNER: You've got... how many stations
do you have in around Greenland?
>> MIKE BEVIS: We have 50 in Greenland.
We have a similar number in West Antarctica.
>> TOM WAGNER: Wow! And any fascinating results
from any of those stations particularly?
>> MIKE BEVIS: Yeah there's a lot,
I mean, for example, you see the places
where people already knew
is the major ice loss
like the Jakobshavn glacier or Thwaites glacier,
there is where you also see the ground rising the fastest.
One of the interesting things is we see that,
almost everywhere it's accelerating.
So for in Jakobshavn it was rising about
12 millimeters a year in 2008.
By the end of 2012,
it was going up like 32, 33 millimeters a year.
>> TOM WAGNER: The ground is coming up 33 millimeters a year.
>> MIKE BEVIS: Yeah, more than an inch a year
just because of the release of the weight of the ice.
>> MICHELLE: Wow!
>> TOM WAGNER: Hey, now, is it hard...
it must be pretty tough to put these stations in,
in the Polar Regions.
>> MIKE BEVIS: It's challenging
because they've got to run all year, right?
And so, for a large part of the year, the winter,
there is no sun,
and so, you have to charge up huge banks of batteries
so you can get through the night.
So these are very large, heavy systems.
I think we spent like $2 million on helicopter fees
just to install G-NET.
Uh all this weight goes in
and then... and then, you...
the sun charges those batteries all summer long
and then you can run all through the winter
and send the data out via satellites.
>> TOM WAGNER: God! Amazing!
>> MICHELLE: Now, the Earth rebounding,
actually sort of bounding up after the weight gets taken off,
it must go very slowly.
This isn't something that just happens immediately.
Is there also something about the history of the ice
and how the ice has changed that's in your data as well?
>> MIKE BEVIS: Yeah, there are actually two...
two ways the Earth behaves.
There's an elastic response,
which is literally instantaneous.
So as you lose the ice, there's an instantaneous adjustment.
But then the Earth also behaves viscously.
It will flow away from a... a stress like a weight.
And that's... in most of the world,
that takes 10,000 years, say, to happen.
So the ground all around Fennoscandia is rising now,
not because of what's happening now,
but because what happened 12.000 years ago
when the ice suddenly disappeared.
>> TOM WAGNER: God, amazing!
Hey, Mike, thank you very, very much for joining us.
We really appreciate you coming in.
>> MICHELLE: Now we're going to take a really close look
at what's going on inside the ice.
And, we're going to start
by looking at the very surface of the ice
because that's where a lot of the melt is happening.
>> NARRATOR: A short helicopter flight
from the edge of the Greenland ice sheet
lies a 27-square mile network of streams
draining the surface of the ice as it melts in the sun.
This summer, an interdisciplinary team
of NASA-funded researchers
set up a camp near the end of that network,
where a large melt pond emptied into an outlet stream,
which then, a few hundred meters later,
disappeared under a snow bridge
and into a stunning and dangerous moulin,
a hole in the ice leading far below.
The team had many tools at their disposal
including drones to map the area
and provide a comparison for satellite measurements.
They also employed what was essentially a boogie board
mounted with a Doppler instrument
measuring the depth of the river and the speed of its flow.
Working in shifts,
they conducted 72 straight hours of measurements
across the stream.
They also made a series of short helicopter flights upstream
and placed floating sensors into three tributaries
to measure the water as it moved.
About an hour later,
the team was thrilled to see all three drifters
pass by their camp within a matter of minutes,
presumably relaying a few last observations
before disappearing into the moulin.
But measuring meltwater runoff
was only part of the effort.
Other researchers joined the team to measure the albedo
or the brightness of the snow and ice in the region.
This albedo determines
how much of the sun's energy will be absorbed,
and therefore, how fast the surface will melt.
From helicopters,
researchers measured incoming solar radiation
and compared it to the light reflected by the ice.
They also imaged the ice using a digital camera,
creating these beautiful high-resolution mosaics
to better map the region.
After a short but intense field season,
the researchers packed up camp and left the ice.
Hopeful that the data they'd acquired
could help shed light on the future
of the Greenland ice sheet.
>> MICHELLE: Now, we're going to go to some of our colleagues,
who are actually out at the Jet Propulsion Laboratory today
and we're going to talk to Larry Smith
from the University of California, Los Angeles
and Vena Chu from the University of California, Berkeley.
And Tom, maybe you can ask them about the research.
>> TOM WAGNER: Hey, Larry and Vena,
thanks for joining us today.
I don't know if you could see it
but we just showed some video of you guys out in the field.
Can you tell us a little bit about your field network
and what it is that you're measuring?
>> LARRY SMITH: Sure, absolutely.
Our project focuses on the hydrology of the surface,
the melting surface of the Greenland ice sheet,
and this is a surprisingly little-studied field
in Glaciology for this part of the world,
but it's an important one for society
and for sea level rise
because, already,
melting of the surface of the Greenland ice sheet
is thought to contribute about half to two-thirds
of the total mass loss from Greenland
as measured by GRACE, for example,
with the remainder being from solid ice calving losses.
But the...
these predictions are very often based on,
regional climate models
and so what our measurements are attempting to do
is to provide some of the first,
real-world "in situ" measurements
of meltwater production
and runoff on the surface of the ice sheets
to try to verify and validate these model predictions
of future sea level rise.
>> TOM WAGNER: Hey, now, Vena,
you're one of the purple that goes out in the field
and does all the hard work, right?
>> VENA CHU: Yeah, I've been going there for
about eight years now. Yeah, a lot of field time.
>> TOM WAGNER: So tell us about some of the gear
you take into the field
and what kind of measurements you actually make?
>> VENA CHU: Well the first goal is just to get the camp set up
so we have multiple tents and all our camping gear.
But we also have, uh, we are measuring discharge,
so the actual amount of water going through these rivers.
So we have a sort of like boogie board set up
that we take across the river.
It's a sort of a Doppler system
that measures how the fast the water is flowing
and how deep the water is flowing.
>> TOM WAGNER: Yeah. So what I can't get over, though,
it seems like you guys are also talking about,
it seems like there has been a big increase recently
in the amount of melting that's gone on
on the surface of Greenland,
and tell us about that,
tell us kind of what you're seeing?
I know that some of the rivers flow pretty fast.
>> LARRY SMITH: Sure.
The satellite record shows that,
while bumpy with warmer years and cooler years, in general,
the overall trend has been an increasing extent, intensity,
and duration of the melt season on the surface of the ice.
But these course resolution satellites
are often microwave-based,
don't have the, the granularity
to see the fine-scale structures and physical processes
that are routing this water off the ice sheet.
And this is actually very important
because one of the key questions is,
how much of that melt on the surface of the ice,
particularly as it expands deeper into the interior,
how much of that melt water is actually escaping the ice sheet
to contribute to sea level rise?
At the moment, our assumption is that all of it does.
But in fact, it's entirely plausible
that perhaps some of it...
some fraction of it, is retained by the ice sheet,
refrozen at the surface or stored within the ice sheet.
And that's why these field measurements
and also higher-resolution satellite
and airborne technologies such as Operation IceBridge,
such as the WorldViews, uh, series of satellites,
these provide additional finer-scale resolution
to study these processes
and confirm that indeed this melt on the surface
is escaping the ice sheet to the global ocean.
>> TOM WAGNER: Thanks! Hey, Michelle,
I understand we might have some video?
>> MICHELLE: That's right. We actually have some video about
what it's like to work in these pretty extreme conditions.
>> UNIDENTIFIED SPEAKER: This is the best time!
How lucky are we to come up here in Greenland!
>> UNIDENTIFIED SPEAKER: Something about this place,
uh, gets under our skins and we keep coming back.
>> UNIDENTIFIED SPEAKER: You can only reach
this area here with helicopter.
>> UNIDENTIFIED SPEAKER: We're camping in the ablation zone.
It's very wet as you can see.
>> UNIDENTIFIED SPEAKER: Water is running everywhere.
It's flowing into these chutes and channels
which are getting bigger and faster with every second.
If someone... goodness help us
were to ever fall into one of these,
uh, there would be no hope.
>> ÅSA RENNERMALM: So we are very careful
with our safety procedures.
The most important here is that we all come back home.
>> GRACE ANDREWS: It is a difficult environment to work in
Um, it's cold here.
There are problems with equipment.
When you have problems with equipment,
it's hard to get replacements.
It takes weeks to get things shipped up.
The temperatures, and in my case,
the sediment load of rivers
makes it hard to actually do the sample collection.
But it's also the most inspiring
and thrilling environment to work in.
Every day I go out in the fields,
I look around at my environment,
the ice, the river, how dynamic it is,
and it reminds me why I'm out there
and I absolutely love it.
>> VENA CHU: One of the hardest things there is
just working in those environments.
I mean, the fact is that we're working in an area
that not many people work uptil, you know,
in the last five, you know, six years or so.
People don't really work on the ice sheet
when it's melting all around you,
just even camping is hard,
and, you know, we're dealing with limited helicopter hours.
So if you need more equipment or something breaks
and, one of the big things that we dealt with was,
you know, how do we keep batteries warm
and, uh, how do we set up camps so that, you know,
rivers aren't flowing around us
and melting out around our tent.
>> TOM WAGNER: Hey, can you tell us a little bit
about what happens?
Where does the water go?
We understand a lot of it doesn't, say,
flow directly off the ice sheet
but it goes into these big holes in the ice.
>> VENA CHU: In fact, these sinkholes are called Moulins.
In fact, what we've seen is that all the rivers on the ice,
the majority of them actually go into these sinkholes
rather than forming long rivers toward the end of the ice.
So we particularly set up these camps right near these moulins
so we can measure how fast
and how much water is going into them.
And, like you were saying before,
the significance of these moulins
and these sinkholes is that
it takes water into the bottom of the ice sheet,
and that's where it can really affect
how fast the ice is flowing.
And, the more that's melting,
the more water can go inside.
We've seen in some of our,
you know, high-resolution satellite maps
that there are thousands of these holes,
thousands of these rivers draining into the ice sheet,
and at higher elevations than we have
ever really known about before.
Just with the availability of better satellite imagery,
higher resolution data we're able to
actually see just how many of these rivers are,
you know, bringing water into the bottom of the ice sheet
where it can affect the ice dynamics and the ice flow.
>> TOM WAGNER: Joining us now is Dr. Sophie Nowicki.
We're going to talk a little bit about the actual work
that we do to understand what's going on inside the ice sheets.
And first, we're going to show you some more video
from NASA's Operation IceBridge.
Hey, so Sophie, tell us what we're looking at right now?
>> SOPHIE NOWICKI: It's a very nice image.
Basically, you're seeing
what is white is ice flowing into the sea,
those low ponds, they are kind of darker.
And you can see that ice has very complex features,
so different types of river of ice...
I mean, river of water.
So those are very different to
what Larry was showing you before.
This is really hard ice.
>> TOM WAGNER: This is actual ice?
This isn't water going into the ocean?
This is something that's like an ice cube out of my fridge.
>> SOPHIE NOWICKI: Yes, and then, you know, ice cube.
So what you can map now with this...
with our measurement tools' capabilities,
it's the actual height of the ice.
And as time goes, you see this is a height of the surface
-- >> TOM WAGNER: Okay. So over here,
we've got our vertical axis.
That's meters, that's height of the ice.
And then what, this is along the flight line itself?
>> SOPHIE NOWICKI: Exactly.
>> TOM WAGNER: Okay. And this is the height of the ice
going down and that's the water out there?
>> SOPHIE NOWICKI: Yes.
And so you can see there's a big drop.
That's where the ice meets the ocean.
And this drop, the second, is going backwards,
at the moment, in time.
>> TOM WAGNER: Whoa!
So that's the ice front backtracking?
>> MICHELLE: It's going all the way back.
>> SOPHIE NOWICKI: Yeah. Like a five-kilometers jump in time.
So it's a very... even though, you know,
you think about ice as an ice cube,
it's actually very dynamic.
It kind of moves back and forth.
>> TOM WAGNER: So -- >>
MICHELLE: Let's talk a little bit about
how this data was taken because this is very dramatic, right?
>> MICHELLE: Operation IceBridge is an aircraft -
>> SOPHIE NOWICKI: Yes.
>> MICHELLE: and the aircraft actually flies over Greenland
and Antarctica and it bounces lasers off the ice.
>> SOPHIE NOWICKI: It does.
One of the measurements that they do is that they measure,
they bounce lasers off the surface
and it goes back, but they also kind of have other measurements,
which hopefully we'll see later,
that goes through the ice.
And what's amazing is that Greenland is so big.
It's about, uh, I mean, a quarter of the size of the US,
but they flow... NASA has flown over quite a big portion
of that over the last few years.
>> ROBERT HALLBERG: So the research, project
that I was involved in this past week is looking at
the calving of tidewater glaciers.
So there are fjords here in Greenland
where the water comes right up to the face of the glacier.
The water down below is warm and salty.
There is meltwater that comes shooting out
through large gaps of the base of the -
of the ice sheets right into the water,
and that creates these turbulent plumes of water
that draw yet more warm water in.
And it's this interaction between the ice
and the ocean that may help to regulate,
how quickly sea level will rise.
Our climate models, because they are global
and have to run for centuries,
we can only resolve down
to scales of order a few kilometers.
And yet all the action of that ice shelf front
is happening on scales of just a few hundred meters.
It's fun and exciting and it's stunning to watch.
But one of our challenges is figuring out
how to incorporate all that... all that action
that's happening in small scales
and put it into global-scale models.
It's absolutely essential.
It's the processes that are going on in the fjords
and up on the ice cap that control
how the system is going to evolve.
We know that sea level is rising,
we know that the ice sheets are losing mass,
but we need to understand why,
because it's only that why that helps us
to project how things will change in the future.
>> MICHELLE: And it turns out that that "why"
is actually kind of a complicated question to answer
because we cannot see directly inside the ice sheets.
>> TOM WAGNER: Yeah. And one of the things
that's always impressed me is,
when you look at the modeling results that came out
of like the IPCC report,
our best projections for future sea level rise;
Sophie, you were involved with that, there is a huge spread.
You know, like we talk about sea level rise
in the next hundred years being,
"Is it a foot, is it five feet, could it be more?"
Tell us about how those models are made?
Like what goes into them, as a start?
>> SOPHIE NOWICKI: So you have to think of a model
as a virtual laboratory that I'm building.
I'm putting all of the things that I think that matters,
so the snowfall, the bedrock,
how the bedrock reacts.
And then basically, we let it mix together
and kind of explore and understand,
the way that if I poke my system,
what's going to happen.
So if you look at my projection,
there is a spread
because we try lots of different scenarios.
Maybe you want to kind of see,
you know, is the snowfall
going to matter more in a hundred years,
is it going to be the ocean?
And as then just showed in the video before,
I mean, ice-ocean interaction is quite complex.
>> TOM WAGNER: Right, but take us back to the basics
just for a second, right?
So you talked about we've got this numerical model
that describes how the ice flows into the ocean.
It also takes... you've got
how much snow falls on the surface of the ice.
But then you mentioned something like the bedrock underneath,
how does the bedrock affect an ice sheet model
that's useful for sea level rise?
>> SOPHIE NOWICKI: So that's a good question
because before Operation IceBridge
we had no idea what the bedrock looked like.
And that's one of the good...for me,
one of the most beautiful return
about Operation IceBridge is the shape of the bed.
It matters because it tells me how big my ice is,
volume of the ice that's available to flow.
So it's one thing, how much ice do I have?
>> TOM WAGNER: How much ice is there? Okay.
>> SOPHIE NOWICKI: But also, it also matters
because, you know, imagine you are skiing downhill.
You go quite fast because it's going downhill.
So the ice is the same thing.
I'm going to go fly... I just go down quite fast.
But if I have to fly... if I have to slide down
if you have skii uphill,
you have to really do lots of hard work.
It's the same thing for the ice.
If the bedrock changes and they have to go uphill,
it's hard work for me.
>> TOM WAGNER: Okay.
>> MICHELLE: And this must affect the way
that the ice is melting.
I mean, if there is this terrain underneath Greenland
that we're only just aware of,
I mean, we discovered this giant canyon system
from the data from Operation IceBridge.
>> SOPHIE NOWICKI: That is correct.
And then also those canyons that are basically
the size of the Grand Canyons,
this is also where some of the water that Larry showed you
going into the surface is going to be trapped
and locked down and those are going to affect my ice flow.
>> TOM WAGNER: So - okay, but one of the other things too
with the bedrock.
So we've been talking recently about Antarctica
and last year we had those papers come out where we said,
"Oh my gosh, part of Antarctica is unstable now
and the sea level is going to rise rapidly!"
Tell us about what they found
and how that affects models.
>> SOPHIE NOWICKI: So there basically...
as Operation IceBridge was flying over,
they managed to kind of
so there is a big bump in the bed,
and those bumps in the bed means that
when the ice is changing due to a warmer ocean,
when the ice is retreating back
into the interior of the ice sheet,
if I have a little low bump
then I can basically anchor myself.
And that's basically why knowing
the bed is so important because,
"Do I have a place to anchor myself
as I'm collapsing or do I don't have a bump in the bed
and therefore I keep on going?"
>> TOM WAGNER: Uh-huh, so literally the...
when you retreat past the anchor point,
the ice pops up and it can begin almost to float.
>> SOPHIE NOWICKI: It can begin to float,
and then it's just like,
you know, when you are
-- >> TOM WAGNER: And we're talking about hundreds,
ice that's how thick, hundreds of feet?
>> SOPHIE NOWICKI: Yes, it is hundreds of feet.
So it's quite impressive, actually,
how dynamic the ice can be.
>> TOM WAGNER: Okay, so getting back to it, right?
You know, people, I think one of the problems
that people get into is they say,
okay, scientists, give us a projection.
You know somebody wants to put a power plant
and they want to know how high sea level
is going to rise in a hundred years.
Right?
We give them a spread that goes, you know,
in a hundred years from now,
it's anywhere from one to five feet,
how does a result like that affect the projections?
>> SOPHIE NOWICKI: Yeah. It's hard
because when you have those...
those projections of like... of the wide range,
it's because it's due to the fact
that we're using different models,
we're using different data sets.
Sometimes, you know, I maybe using in my bed
and then somebody else is using in a different bed,
and so those all come to play in a way that we couldn't know,
and that's why the spread is actually at the moment,
you know, is good because we'll...
we have something to try to work forward to refining,
and NASA is doing a huge amount of work
to refining this spread,
because of course I'm not happy to tell you,
I don't know if it's going to be one feet or five feet.
I would rather be able to tell you it's going to be
two and-a-half foot for planning.
>> SOPHIE NOWICKI: But at the moment,
this is just the way it is,
the future is real uncertain
and that's what we're dealing with.
>> TOM WAGNER: Hey, guys!
>> JOSH WILLIS: Well, yeah, the...
the oceans are definitely eating away at the,
Greenland ice sheet from the edges.
We've known pretty well, for a long time
that the surface is melting.
We can see that melt from space.
And, you know, Larry and Vena
were out on the ice
watching the rivers of meltwater dive down into these moulins,
but, more recently,
research has started to suggest that,
the ice is actually being eaten away at the edges.
Remember, a lot of these glaciers which carry the ice
away from the ice sheet and into the oceans
actually sit right in the oceans.
They literally have a toe in the water,
and that makes them susceptible to warming
and the intrusion of warm water
from the edges which can melt away at the glaciers.
>> TOM WAGNER: Tell us a little bit about
like the continental shelf around Greenland,
its relationship to the ocean,
and that's relationship to the ice?
>> JOSH WILLIS: Well, what's really interesting,
Tom, is that the water around Greenland
is sort of upside-down.
You have warm water
underneath a layer of cold water.
Normally, it's the other way around, right?
Warm water rises.
But the waters around Greenland are actually,
what we call "inverted,"
meaning that the warm water is actually at depth
and it's at depth because it's extra salty.
This water comes from the Atlantic,
it's a very salty ocean.
The cold water comes from the arctic
and it's very fresh so it sits on top.
What this means is that the warm water has to climb up
the continental shelf and reach into the fjords
in order to interact with the glaciers.
So one of the things we're really interested in is
just how that water might get there,
what pathways it might take along the continental shelf.
>> TOM WAGNER: We're showing some video now
of what it's like to do that work.
Can you tell us about the oceanographic measurements
that you actually make and what goes into making them?
>> JOSH WILLIS: Yeah, absolutely.
So this is really exciting because,
this ship has sailed into a fjord,
which is a long trench carved by an ancient glacier
and is now filled with water and they're,
deploying instruments.
Some of them are called 'moorings'
which sit on the bottom and collect data for a long time,
and some of them are CTDs which,
are one-time measurements of the ocean.
You can see the ship pushing away icebergs
and folks paddling through the slush.
It's really hard work, and it's really difficult.
And, right now, we actually have a ship,
the 'Cape Race' which you see right there
at the end of the video,
which is collecting data about the shape
and depth of these fjords,
because that's really important
for understanding how that warm water
can climb up onto the shelf and reach the glaciers.
>> TOM WAGNER: So tell me a little bit.
You go out and you make a few point measurements, right?
How do you synthesize all this stuff together?
You know to get at those big...
like, what are the big picture-specific questions
you're trying to answer
and how do you put all those things together?
>> JOSH WILLIS: Well, most people would tell you a model,
but I'm going to say, you just need
a whole lot of those point measurements.
In fact, we've only just begun
to study the oceans around Greenland.
While there have been a lot of,
moorings placed
and some surveys that have happened for a long time
in a very few places, the vast majority of the area
around the island of Greenland is just unmeasured
in terms of the ocean,
not just how salty
or how fresh or warm or cold the water might be,
but even how deep it is.
In fact, there are huge areas around Greenland
where we have no depth measurements so we don't know
if there are deep trenches, or sills
that this warm water might have to climb over.
So we have a whole lot of observations to make, and,
right now we've actually begun making
those kinds of observations with the new mission,
'Oceans Melting Greenland' or 'OMG'.
>> TOM WAGNER: Yeah, and I think we're going to share
some video now of how the aircraft work for OMG.
>> MICHELLE: So describe this mission here.
>> JOSH WILLIS: Yeah. So what you're seeing here
is, an aircraft
measurement of the height of the ice.
And, this is a measurement that will fly once a year.
We're also measuring ocean temperatures
using deployable instruments.
So these are being dropped out of back of the aircraft
They fall through the water and measure
temperature and salinity,
and then a small float actually radios that data
back to the airplane.
So those two campaigns will happen every year
for about five years,
but we also have, ship-based measurements
of the sea floor depth,
and finally, an airplane that measures gravity.
And the gravity measurements are important
because that also tells you about
the depth of the sea floor.
Whenever you fly over a trench,
the pull of gravity is a little bit weaker,
and that's how we can infer on a lot of places
where we can't drive the ship,
we can infer how deep the water is.
So all four of these campaigns are part of the
Oceans Melting Greenland Mission which started this year.
We have the ship in the water right now,
and next year we'll be starting to fly the airplanes.
>> MICHELLE: The really dramatic interface of the land
and the ocean and ice.
Can you tell us, is there anything special about
the geography of a fjord that affects how the ice
and the ocean work together?
>> JOSH WILLIS: Uh the glaciers dug out these trenches,
uh, on their path off the land
and towards the ocean
and left behind avenues for this warm water
to sneak up from the deep and interact with the glaciers.
So a lot of what scientists are focusing on today
is this interface where water meets ice meets land
because that's where the real action
is in terms of the ocean-ice interaction.
As we heard about before, a lot of the meltwater
from the surface actually digs down through the ice sheet
and it finds its way to the ocean actually
at the bottom of the ice.
So it often, you know, in some cases,
it comes out right at the bottom of the ice,
and then because it's light
and fresh, it surfaces.
That can pull warm water
in towards the bottom of the glacier
and increase melting, and that's what
we're really looking for with OMG.
>> MICHELLE: So here we see these little arrows
are indicating the flow of the ice?
>> TOM WAGNER: Right. So here we are,
the blue is the ocean.
Those blue lines are showing
the direction of flow of the ice.
And you can see what happens is it's kind of slow on the sides,
then it gets into this racetrack in the middle
and it goes out to the ocean.
And what's so fascinating about this is that
you can see kind of right at the front.
This stuff is like... some people call it
like the cork in the bottle, you know.
And that... these processes that Josh's team
is studying under OMG,
they are looking at how the ocean causes
the ice to fracture more easily,
pull that cork out of the bottle,
and let the ice behind it speed up
and really dump in the ocean.
>> MICHELLE: We're really seeing just how many
complex interactions are going on here that
as the air warms that affects the ice,
as the ocean warms that affects the ice as well.
So this is one of the reasons we see
such dramatic changes at the poles.
>> TOM WAGNER: Yeah, and it's one of the reasons
that NASA gets involved in this work.
You know you need a lot of new technology to do this.
A lot of its remote sensing which means
we make measurements from far away,
from aircraft or satellites.
But then we kind of take the view of trying to model it
and pull all those little pieces together.
This is a Jakobshavn glacier from Greenland,
one of the most important outlet glaciers,
it drains quite a bit of Greenland.
This is where the front of the glacier was in 1850.
This is where the glacier was today.
And this is actually, really recent stuff
from just a few days ago, that shows you just how much
ice can be lost over the course of a couple of days.
>> MICHELLE: So we're actually seeing ice
cracking up right there,
that's the change that we're looking for?
>> TOM WAGNER: Right. >> MICHELLE: Yeah.
>> TOM WAGNER: But I mean -- and you are talking,
again, this is like
kilometer-scale type events, you know.
>> TOM WAGNER: This ice, actually here is
some footage of the thing itself.
So there are some great pictures of these,
but what people have done is compared the sizes of
the chunks of ice breaking off to like buildings.
And so, some of these chunks you're looking at,
they are like as big as the US Capitol building.
>> JOSH WILLIS: I think, you know,
one of the striking things about that image of the ice
breaking off is the timeline that's associated with it.
If you look carefully,
that data goes back to the late 1800s.
So this glacier has been retreating,
steadily for the last 150 years.
And it's happening, you know,
on a glacial time-scale, very rapidly.
So we're really interested in trying to study just
how these things are proceeding
and what the role of the ocean might be
in helping to drive them.
Clearly, if those things are being eaten away at the edges,
we need to be able to quantify that
if we ever hope to predict sea level rise into the future.
>> TOM WAGNER: Hey, Josh!
Now you are kind of a man who's a Jack of all trades.
We're also going to talk now about Jason-3
as we kind of finalize our program
and we're going to start talking about
what are the things that are coming next for NASA.
Can you tell us a little about Jason-3?
And I understand we have a picture of it
to put up that you might talk to.
>> JOSH WILLIS: Well, the Jason missions
are really in my opinion,
one of our most important means
of measuring the human impact on the global climate.
Because these missions measure the total volume
of the ocean basically once every ten days,
we can really watch how,
the entire planet is responding to climate change,
with kind of one single number,
and these satellites have been providing
that record since the early 1990s,
and we're really looking forward to Jason-3
in order to continue that record.
A lot of folks ask, "Well, what's new about Jason-3?"
And I like to say, "Well, it's going to measure
the next five years instead of the last five years."
And really, that's a big deal in climate science.
A lot of what we need are long records to be able to compare
what's going on to the ice
and the oceans today with how they were decades ago.
>> TOM WAGNER: I think what people forget is
some of the big components of the Earth's system,
they behave on decadal timescales.
Like the Pacific Decadal Oscillation.
So tell us a little about that.
>> JOSH WILLIS: Yeah, absolutely.
One of the things that,
the satellite altimeters
do is they measure sea level,
not just everywhere around the globe,
but in each place around the globe.
So you can see clearly where the Pacific Ocean
is rising quickly, like in the West Pacific
near Indonesia and Australia.
They've been getting hammered with rates of sea level rise
that are three times as large as the global average.
So they are getting way more than their fair share
of sea level rise.
We on the West Coast, here in California,
have been getting less than our fair share.
In fact, in some places sea levels have actually
fallen very slightly, and that sometimes can give us
a sort of false sense of security.
You know, global sea levels are rising
and we're going to have to pay that debt of,
sea level rise that we didn't get in the last 20 years
probably sometime in the next 20 years.
>> TOM WAGNER: Josh, thanks a lot for joining us today!
We really appreciate it!
Good luck with that mission!
>> MICHELLE: So we've talked a lot today about
all kinds of different scientists
that are studying ice,
that are studying ocean level rise,
and one of my big questions is, "What comes next?"
>> TOM WAGNER: Yeah. So NASA has actually got
a bunch of missions coming up
that's going to help us with this.
You know, so the next thing that's going to happen
is the Grace Follow-On Mission
which we're hoping is going to provide a higher resolution
look at this mass loss and change of the ice sheets.
Then after that, we have the ICESat-2 launch.
An ICESat is this laser altimeter that goes and --
literally, it's like a laser pointer in space,
tells us very precisely the height of the ice
over the entire planet.
It even also gets used to measure global forest
heights and abundance.
And so then after that we will have
what's called the NISAR Mission,
which is a mission jointly with India,
that's a new radar mapper, that's going to tell us
a lot about how the velocity of the ice flow
to the ocean has been changing.
So what we are really hoping is that we can pull
all this information together
and really narrow down those error bars
on the estimates of sea level rise
and help society plan.
>> MICHELLE: And it may surprise you to know
that so many NASA resources are being used to study the ice,
to study the Earth.
So when people ask you the question,
"Why is NASA studying ice?"
What's your answer?
>> TOM WAGNER: You know, it's a pretty simple answer.
This is global question.
You need to measure all the different parts of the system
at once and you need different technologies to do it,
and new technologies,
and that's what NASA excels at, you know.
And so we build the satellites and the technologies
and the aircraft to make these kinds of measurements
and we put people in the field to help pull it together.
But I should say too, we also work with our partners.
You know, the National Science Foundation,
the Department of Energy, NOAA, the USGS,
they are also all working on this problem
and we all work together.
>> MICHELLE: So NASA is studying many different aspects
of how the oceans are changing,
and this is something that's happening right now.
This is something that's going to affect all of our lives,
no matter how close we actually live to water.
So on behalf of NASA and all the scientists of NASA,
one of the things I can say is,
our Earth is changing, and at NASA, we're on it.