>> From the Library of Congress in Washington, D.C.
[ Pause ]   >> Good morning.
I'm Jennifer Harbster a research specialist in science technology
and business division here at the Library of Congress.
I'd like to welcome you to today's program:
Big Ice Sheets Doing Big Things: Why it is a Big Deal.
In his presentation we will learn why we need accurate models
to predict the shrinking Greenland and Antarctica ice sheets.
This program is the fourth in a series of programs in 2011 presented
through a partnership between the NASA Goddard Space Flight Center
and our division.
This is our fifth year presenting programs with Goddard.
Our speaker today, Dr. Robert Bindschadler is no stranger
to the Library of Congress.
In 2007 he visited the library and talked about the warming
of the polar regions in the presentation:
Who Left the Freezer Door Open:
What the Poles are Telling Us About Climate Change.
If you're interested in watching this presentation you can go
to the library's webcast page which is at, you can find it at loc.gov
and you can just simply type in NASA and climate change.
Dr. Bindschadler received a bachelor's degree in astronomy
and physics from the University of Michigan, and a doctorate
in geophysics from the University of Washington.
He recently retired as chief scientist at Goddard's Hydrospheric
and Biospheric Sciences Laboratory after 30 years at NASA.
In addition to his position as emeritus scientist
at the laboratory, he is also the senior research scientist
at Morgan State University in Baltimore.
Dr. Bindschadler is one of the world's experts
on the earth's glaciers and ice sheets.
He has led 15 Antarctic field expeditions
and participated in many more.
He has published over 140 scientific papers.
He's served as president as the,
of the International Glaciological Society, is editor of the Journal
of Glaciology and has also testified numerous times before congress.
And I'd also like to note, he was also asked to brief Al Gore
when he was vice president on the stability of ice sheets and shelves.
So it is my great honor to welcome Dr. Robert Bindschadler back
to the library.   [ Applause ]
>> Thanks very much Jennifer and, thank you all for coming.
As Jennifer said I've been here before.
Actually I I kicked off the set of lectures
that Jeannie Allen has organized with the library
to bring earth science to you.
And maybe even more than earth science.
I don't know if it's extended to space science,
but earth science is is my beat and what I care about most.
So it's good to be back.
I could just say, just remember everything I said back
in 2007's even worse now and just [laughter] leave the stage,
but I won't do that.
I'll remind you of of some of what's going
on because it is actually quite exciting as a scientist
but of concern I think for, should be,
for people on the, on the planet.
And just referring to Jeannie one more time,
on many of the years I spent at at Goddard I was in an office
across the hallway from Jeannie and it was she that said that,
okay you give wonderful presentations but you really need
to talk about yourself a little bit at the beginning.
So so now that she's in the audience I dare not,
not do that 'cause she was absolutely right.
And and often I like to talk about being a scientist to the kids.
They're great audiences, but you are as well.
And so I'll I'll just truncate this sort of self-intro- introduction
by saying that being a scientist is one heck of a lot of fun and I get
to fantasize about, about sort of standing in the shadow
of these two major figures, Sherlock Holmes and Indiana Jones.
Why do I pick those two?
Because Sherlock Holmes solves mysteries
and that's actually what led me to be a scientist.
I loved reading mysteries and I I'm still have the privilege and
and fun of solving mysteries.   That's what scientists do.
And because many of my mysteries lie in pretty remote areas,
I also get a little bit of adventure laced in with with that effort so,
so I get to play both roles.
And I'm not gonna inspire any of you I think to change your careers
and become scientists, but I'm sure many of you influence the decisions
that many children make and tell them
that that science actually is is really a very rewarding and fun
and enjoyable career, and you get paid for it.
So what could be better?
Just to lay out what I'm gonna talk about today, I'm going to step,
I'm gonna start not by talking about ice but just talking
about earth science in general and a few important concepts.
And it's because it's very important for earth scientists
when we have opportunities like this to speak to general audiences
to get some of these points across.
And the basic structure of the talk is letting you know what we know we
know, letting you know what we know we don't know, what we think we know
about the don't knows, [laughter] and how we're gonna fi- how
and when we're gonna find out more about the don't knows.
And then and then finally what you should know when you leave here.
So that's that's the basic outline of the talk.
So the important concepts that that I do want to touch on before I focus
in on ice are these are these three.   That big and fast do matter.
Weather versus climate, there's a lot of confusion out in the
in the community about that.
And there's also conf- confusion in my community
about what scientists should do and what they shouldn't do.
And as I said, these are general statement I'll be making.
First of all, the time scale matters and when you hear people talking
about earth science observations, it's very important
that they specify and if they don't that you have clear
in your mind what time scale they're talking about.
Big changes that take 10,000 years to occur are gonna be less,
of less concern than even smaller changes that happen much faster.
So, and it's because of this time scale issue
that earth scientists are so concerned about what's changing.
Things are changing really fast and it's that range of change
that matters so much, and often more than the magnitude.
It's how fast they're changing.   Just keep that in mind.
And so i- if I see small or brief changes,
that makes a great scientific paper
and I'll tell my colleagues about that.
But you probably won't hear about that unless you read some
of these very technical journals.
If I see large changes my phone is probably ringing
because a reporter wants to hear that and
and you may read about it in the paper.
A big iceberg calving off, something like that.
But if I see large changes that are sustained, that's when I go
across the street and and because people
in congress want to know about it.
So and it's, and it's because we're seeing in my world,
the world of ice, these large and sustained changes that put us
on a trajectory of of concern that I have testified a number of times
across the street to various committees.
Oh, [inaudible] punch line there, we tell congress
when we have large and sustained changes.
They're usually quick to ask, by the way.
They really are on top of things.
Weather and climate are not the same thing and I want
to really get this point across that weather is things that happen,
you know, changes in our climate that that that occur
on the minutes to months time scale.
That's why time scale is so important.
But climate is something on the decadal to century time scale.
So so it's very easy for the for the discussion
about these two concepts to to get confused.
And and the best metaphor I can give is that weather is
like rolling the dice, and climate is like rolling the dice a lot.
And the uncertainty of these two is very, very different.
This is why casinos make money.
They un- they are sort of in the climate business.
They know the statistics of they have lots of customers
and over time this is how th- the odds are going to lay out and
and they make their money on knowing knowing that very precisely.
So if you have a pair of dice and you roll it,
I I can give you my best estimate of what you're gonna come up with,
standard dice would be seven,
and one out of six times you'll roll a seven.
But, five times I'll be wrong.
But if you roll those dice 100 times or 1,000 times or a million times,
the more times you roll it I can get really precise
about how many 7's you're gonna get.
And so that's why climate prediction actually is getting very good even
though weather prediction has has been quite a struggle.
They are different, very different.
And climate change just to extend this metaphor one more slide is is
like loading the dice.
It's really defining a new normal if you will,
and that we're still gonna see much the same kind of weather.
It's gonna be variable and it's gonna be hard to predict,
and so any single weather event is not direct evidence
of climate change.
It cannot be done and any scientist that says it is wrong,
and any non-scientist that says it, is wrong.
Weather is weather and climate is climate.
However, by loading the dice you're really changing climate and and
and again in in this metaphor we'll see familiar weather
but the likelihood of those events will be changing.
The statistics will change.
The odds of of of particular weather patterns will change.
That's what climate change is about and and I hope that helps.
And then finally I said I wanted to talk about the scientist's role.
This is what we do.   This is what we should be doing.
We observe.
We try to understand those observations in in the sense
of how different elements in, that we're observing interact.
Peer review, this is our community.
We we are, and my wife will attest to this, very critical people.
Critical in the sense that we critique things.
Sometimes we think we're critical in the other way too
and I think we are but, but I'm talking more
about about we self critique our own work extremely rigorously
and that's the peer review system, and it works very, very well.
So that's an aspect of the of the community that's important.
And then this reporting function is becoming more and more important.
I was saying to a few people here before before we started
that communication of results is now part
of what an earth scientist needs to do.
It's not just talking to ourselves,
it's it's telling people what we understand.
And finally here it should not be, and too often some of my colleagues,
and I try to catch myself too, the role of a scientist is not
to advocate a particular response, it's to provide the information
to talk about the what if scenarios and the if this happens then
that is likely gonna happen as well as we understand it.
It's not we should take a particular position and certain policy.
Scientists should not be doing that.   Okay my message today?
So here we get to the ice part.
We just recorded the most dramatic decade
of of ice sheet changes ever witnessed and this is,
this is where the science that I do really gets fun.
We're, we're saying things that that when I was learning the trade
and glaciology in graduate school we didn't even think ice sheets
could do.
But not only do we have evidence that we, that they are doing some
of these things, and I'll I'll be more specific later,
we have actual observations that that they're doing those things.
Society is extremely vulnerable to sea level.
This is the direct connection between why ice sheets matter.
A lot of ice contained in ice sheets.
As they shrink, sea level goes up and society around the world--
this is the global "we"-- are very vulnerable to that.
There's there's some obvious reasons for that.
We love being close to the ocean.   High priced real estate.
Economies.
Develop ports and so and, navies build and operate ships
that are all at at the sea, coast.
I'm not gonna give this one away, ice sheets will continue to shrink.
I'm, that's part of what I'll be talking
about so so stay tuned on that.   And as as direct consequences
of of what ice sheets are doing, sea level will increase.
We know that, that's one of the things that we do know.
And the rate of rise will likely increase.
That's one of the things we don't know
but we think we know something about that.
And our best estimate, many people need numbers,
these people across the street included, and right now keep
in mind this one meter rise in sea level by the end of this century.
That's really the best number my community has come up with so far
and I'll I'll give you a little bit more information about that.
And we will get better with time and I'll be talking about that too.
What we know we know, what we know we don't know
and how we're gonna find out more about the don't know's.
Okay, ice sheets.   They're really big.
You know if I could tell you one thing
about ice sheets I really wanted to emphasize, they're huge.
I mean Antarctica is a continent and it's not, it's--
seven continents and it's not the seventh continent in terms
of size, it's the fourth.
It's right right in the middle of the pack.
It's it's larger than the United States, including Alaska.
You have to throw in Mexico to get
to get enough surface area to match Antarctica.
It is enormous.
And 90% of all the ice on the planet is contained
in that ice sheet-- the Antarctic ice sheet.
So there's a lot of ice there, enough that if you melted just
that ice sheet alone, sea level would rise 55 meters.
So that's the Big Kahuna.
That's that's the one that that you know where the massive signal is.
The Greenland ice sheet is the other ice sheet,
sort of the lesser of the two.
And 9% of all the ice on the planet is contained
in the Greenland ice sheet.
So you add those two together and you're already at 99%.
You only have 1% left, and that's the 1% you may be more familiar
with, the glaciers and the small ice caps are sprinkled
around high altitude areas, mountain chains around the world
as well as some polar regions.
So there's a lot of ice on the planet and it has waxed and waned.
So when we talk about that one meter rise in sea level,
there's so much ice, if you add all of this together,
that's enough to raise sea level 65 meters.
So, so we're not talking about a big change in the ice sheet
when we're talking about what it would require
to raise sea level one meter.
Actually it's only like 1% decrease in the size
of the ice sheet and we're almost there.
That alone would give us 65 centimeters,
two thirds of the one meter.
And then there are other effects, the thermal expansion of the ocean
that can take us the remainder of the way.
So, so we're not talking about a big change in the ice sheets,
we really won't notice that they're not there because most
of them will still be there.
But yet society will be, have to deal with this one meter rise
and I'll show what that means very shortly.
So what we know, what we know.
Looking at the past, this is more paleoclimate information
and I'll just list these things that, some major things that we know
and then show you some data as to, to sort of back up the statements.
Ice sheets shrink in a warmer climate.
Well duh, you know that's that's.
. . although there have been those that said,
okay in warmer climate we expect--
and there will be and we've measured-- increased snowfall.
Because a warmer atmosphere holds more moisture, it will snow more.
And that in fact, does occur.
But it's it's it's more than outweighed by the loss of ice
by those warmer temperatures and and so there really is no doubt
that in warmer climates there's less ice.
And we're headed that way.
We also know that, you've heard about the ice ages
and what we call the interglacials, those periods between the ice ages,
as as the size of the ice sheet and the temperature
of the planet has has has col- has become colder and warmer and colder
and warmer and the ice sheets grow and shrink and grow and shrink.
Well the last time we had an interglacial, a warm period,
sea level was higher than it was today, than it is today,
by about five meters, and both Greenland
and Antarctica were smaller and they both contributed to that.
And we know we know that from various lines of evidence.
So it has been higher.
We also know that the rate at which sea level rises, and I said rate
of change is really important and this is one instance where,
where that comes to the fore.
How fast sea level rises is a really, really big deal
and again we have records that indicate that--
we have observations that tell us
that sea level the last century was was increasing only
about two millimeters a year.
That's not much, although when you think about how,
how shallow the slope is at the coast,
that two millimeters vertical rise does actually translate
into 1,000 times, 100, 1,000,
sometimes 10,000 times more horizontal movement
of the of the, of the coast.
So it amplifies what may seem like a very small vertical change
into a much larger number.
So it was about two millimeters per year last century.
This century it's it's already started to increase.
It's it's past three now.
The highest number I've heard so far in the last couple years is
about 3.8 millimeters per year,
so almost twice what the average was last century
and satellites are very good at at measuring this in a global sense.
But we have geologic evidence that that says
that in the past sea level has risen 10 times faster than that.
So again that's not hypothetical.
Those those are direct evidence that that sea level can rise much faster
than it is even at present.
And I'll talk quite a bit about tidewater glaciers.
I'll, I'll explain here, a tidewater glacier is a glacier that comes
out of the mountains and goes into what would be a fiord if the ice
and the glacier wasn't filling it.
So it actually comes in contact with the water and fills that fiord
and displaces that water.
Tidewater glaciers are are useful glaciers to look at in terms
of the dynamics because because they they do exhibit some very dramatic
behavior, and a lot of the ice sheets drain
through what essentially are tidewater glaciers,
glaciers that are thick enough and and big enough and move fast enough
that they just flow right out into the ocean.
And so the dynamics of tidewater glaciers, whether they appear
in Alaska or at the edge of an ice sheet, are quite important.
And we know that this dramatic and episodic behavior
of retreat is something that they, that they are capable of
and I'll speak more about that in a moment.
So, on the less ice is, less ice in warmer climates, this is just some
of the evidence-- if you line up on the top, this is a record
of sea level as it has raised and lowered over time.
Less ice is is the upper part of that and
and more ice is the lower part of that.
And you line that up with the temperature record that came
from an ice core drilled at Vostok Station in Antarctica if you care
to know that takes us back 400,000 years and there are ways to extract
from that ice what the what the average temperature was.
It also has fluctuated, colder warmer, colder warmer,
as we went through these glacial interglacial cycles.
And you line those two up and so the last 400,000 years,
every time the earth is getting warmer, it's losing ice.
And these records go back more than a million years now.
It just happens every single time so there's just no doubt,
that's why I can say with absolute confidence, we know we know this.
And I mentioned, I spoke to the rate of sea level.
This is just some data that was pulled together on,
from the end of the last glacial period 20,000 years ago how rapidly
sea level rose between then and now.
And you see that that that it has risen
and for the last 8,000 years it hasn't been rising very rapidly.
That's where that curve gets quite flat.
I don't tend to like to point
at charts 'cause it's often hard to follow.
But up here, this is when most of society developed,
you know from the last 8,000 years.
So we, we became comfortable with the world and and societies
and cultures evolved in the midst of of a climate
where sea level was not rising particularly rapidly.
So we kinda set ourselves up-- had had we-- to be vulnerable.
Had we developed during these meltwater pulses
when there was sudden losses of large fractions of the ice sheet,
we might have learned to become more wary of of living close to the coast
or at least developed our infrastructure a little
bit differently.
But this is just to say that that there is evidence
that that sea level has gone through periods of time
where over the course of a few centuries it's rising more
than 10 times faster than it is today.
So, and this is because of ice sheets.
There's really nothing else in the climate system
that can cause sea level to go up that fast, at that kind of rate.
So, these are ice sheets speaking to us from the past.
I mentioned tidewater glaciers, I said a little bit,
I'll say a little bit more-- this is just a couple of pictures
to illustrate, i- if anybody shows you this and they talk about, okay,
glaciers are retreating worldwide.
Well this really isn't a fair example to to show.
This is a tidewater glacier, one that retreats exceptionally rapidly
and over the course of a few decades it had filled that fiord and it
and it retreated back around the corner.
And so again we we know that this happens, we've we've observed it,
and we have lots of paleoclimate data to tell us that lots
of glaciers have done this.
I'll speak a little bit later about the process by which it does that.
Okay so what do we know about the present?
This is still the what-- what we know we know.
And again I'll just emphasize this that it has been a,
an incredible decade for for glaciologists
to to s- witness what's going on.
It's it's not the hypotheticals that we have been studying
in in decades past, we're actually seeing things happen right before
our eyes.   Thanks to satellites I should say.
I should give the nod to NASA there.
They and and other space agencies have just,
we've gone from a data starved situation--
where you had to go to the field and set your tent
and make a few measurements to know anything about what was going on,
and these areas, like I said, are really big--
to a a data rich environment
where satellites are collecting just a wealth of information.
So we know what's going on there, and and that's been fundamental
to us being, making, becoming aware
of of these these changes 'cause it has not always been so.
I'll emphasize in in a, in a diagram a little bit later
that the largest changes are happening at the margins.
And a couple of ways we see that is
that these large floating ice shelves, these big plates of ice fed
by the ice sheet, are rapidly disintegrating,
and that the outlet glaciers are accelerating.
And that's, that's a way that the ice sheet loses mass.
And it's losing mass faster than snowfall can replenish it,
and that's why this next bullet,
the increasing rate of ice sheet mass loss.
The ice sheets are shrinking faster and faster.
I'll illustrate that again.
I won't talk any more about the nearly all glaciers are retreating
because even if you got rid of all the other glaciers
and just set ice sheets aside for the moment,
you would get about half a meter of increased sea level.
Not even quite that now so.
So that's important, it contributes, but it's not,
it's not gonna break the back of of society.
And then finally I just want to hammer this point home
that that society is exceedingly vulnerable to sea level increases.
I think I, so I'll I'll illustrate each of those points here.
So, now the ice sheets are colored by, in colors that represent where,
how how the elevation of the ice sheet is changing.
So is the ice sheet getting thicker or thinner is is,
is identified by color here with the browns and the and the purples being
where it's getting thicker, although the rates aren't as high,
as the greens and the blues where it's getting thinner.
And you see the green and blue areas are always around the coast.
It's always around the coast.
So it does snow a little bit more in the interior
of the Greenland ice sheet.   That's that's a fact.
It's been measured by satellite altimeters.
But it's losing mass much faster
around the edges because it's thinning.
Again, satellite altimeters tell us this.
And it's not everywhere.
It turns out that the areas that, around the margins
that are thinning most rapidly are those where you have fast,
deep glaciers draining the ice back into the ocean.
And that was an important clue as to what was going on.
And, okay, so I indicated disintegrating ice shelves
as one of the big surprises.
This this was probably the biggest surprise,
the biggest early surprise certainly.
This is the Antarctic Peninsula I show, I show just in that inset
on the lower left where it's from, and 200 miles long.
So from here to New York City just to give you an idea of the scale.
And so these ice shelves that you see disintegrating
in in this time lapse are not, are not small.
They are, they are hundreds of square kilometers.
Another important aspect of them is that they grow very slowly
because you have to have snowfall accumulate in the mountains
of the peninsula, form a glacier, that glacier flows
out onto the ocean, the ocean kind of eats away at it
so it it keeps feeding ice and eventually over thousands
of years, these ice shelves form.
But they're disintegrating in a matter of weeks.
So I mean the the difference
in the time scale there is just enormous-- orders of magnitude.
So that was why we were so astonished
to see these ice shelves are here today, gone tomorrow.
Or here yesterday, gone today.   This was a really, really big deal.
Just some figures from a paper, I apologize, it looks confusing.
The important part is is the the words outlined in the colors there
that we were able to monitor two of these glaciers,
'cause there was this big debate in the community, ice shelves matter,
nah ice shelves don't matter.
And this this settled that that disagreement.
It said that the glaciers that feed an ice shelf notice
when that ice shelf goes away 'cause some people said it just
wouldn't happen.
Well, nature gave us the perfect experiment and it got rid
of ice shelves in matter of a few weeks,
and these glaciers accelerated.   Not a little bit but a lot.
I mean you see the numbers there.
In just two years, two of these glaciers that we had good speeds
on before the ice shelf went away, so that was sort
of the the the initial state--
they sped up by a factor of four and a factor of five.
So they knew and they responded very quickly
to the loss of that ice shelf.
It's nice to have a debate in the community resolved so clearly
by Mother Nature where where there's
where there's just no disputing the the results.
And so this glacier's accelerated and I was, I've been talking
about accelerating glaciers and and that's off,
that's off in the peninsula here, that 400% increase
and 510% increase, but we've also measured acceleration
of glaciers in many other areas.
And those areas are those same areas that are thinning.
So as you get thinning, that's kind of occurs in lockstep
with the acceleration of the ice and also the retreat.
I'll show the retreat slide in a moment, but again,
the numbers are not small.
Glaciologists are are accustomed to smaller numbers,
things happening much more slowly on an annual basis.
These in some cases are the change over a five year average period,
but, but still they're they're big.   They're big.
They're an extra couple of digits.   We weren't used to this.
So it's it's a far more dramatic world
that that glaciologists are having to deal with.
That's what ha- what's happening at the coast,
but again the concern is overall is the ice sheet getting bigger
or smaller?
Well these numbers say that overall the ice sheets are getting smaller.
And lots of people are studying,
studying this with various data sets.
That's why there are so many different color boxes.
Every colored box there is another scientific paper dealing
with some data set in some way to get a a handle on some period
of time whether the ice sheet-- in this case, Greenland--
is getting larger or smaller.   So so the the time period is,
they're all ordered by time down here.
So this this was 30 years ago and this is now.
And the vertical is how rapidly it's losing mass.
If it's not losing mass at all, it's up here at zero.
The mass balance, balance between accumulation and melting
and discharge are, they balance each other.
So no no change in the mass of the ice sheet versus a greater
and greater rate of mass loss, all the way down until you get
to 360 gigatons per year.
And that doesn't mean anything to you.
A gigaton is a cubic kilometer.
That still probably doesn't mean too much to you.
But to put it in terms that may mean something to you,
360 gigatons per year will raise the ocean around the world a millimeter.
That's, so these are big numbers.
That's a big change in sea level, a large fraction
of what we're already measuring.
And and your eye tells you what's going on.
Now once you, you know, the individual scientist
that wrote individual papers here will will have,
will have laborious arguments about my number's right,
your number's wrong, no my number's right, your number's wrong and
and it wasn't until we put all all these numbers together
and we said whoa you know, the big picture is just irrefutable
that the ice sheet used to be far more stable just 30 years ago.
I got my degree right here in 1978.
Everything was fine, and then the world has just been turned
on its head and Greenland is just losing mass faster
and faster and faster.
How 'bout Antar- Greenland's the small one, how 'bout Antarctica?
Same picture.   Same picture.
It's it's bigger, there are fewer studies, it's just harder to collect
and and analyze data for an ice sheet that's 10 times the size
of Greenland.
But a lot of people have taken that on, and you arrange their data,
you know you leave them in the other room arguing
about who's number's right and you just take all those papers
and you put 'em on a single chart and you get the same picture.
It used to be more stable and
and it's losing mass faster and faster and faster.
So this is happening.
Okay let's let's talk about the impact just briefly.
Again, I always key in on this one meter of sea level rise,
and if you look at the map of the world this is just the earth
at night; you may recognize that famous image.
And just color in red all the areas of the coast that would be flooded
with a one meter rise in sea level,
and you can see instantly why this is not a polar problem,
this is a global problem because all the continents end at the coast,
so there are coastlines all aro- all around the world.
Some of them are are very heavily populated.
Bongaladesh right here, Irawati Delta right here.
And the US isn't, you know, we have New Orleans down here.
You have the Piedmont area, virgi- southern Virginia
and North Carolina-- there are a lot of areas
Let's view it another way.
This, this picture down at the bottom is the Maldives and and wi-
in all seriousness, the prime minister
of the Maldives held a cabinet meeting underwater.
Everybody, all the all the cabinet officers put on scuba dear--
gear and they had a table under the water
and he had a cabinet meeting there--
this was just before COP 15 the Copenhagen climate meeting--
to make a point, that his country is is a set of islands, and this is one
of them -- and it's a typical one-- where they they can't,
they can't suffer much of an increase
in sea level before their entire country-- not their coastline--
their country is flooded.
And again in all seriousness, he was at the meeting trying to negotiate
with the prime minister of some other country to move his country,
as a unit, 'cause he doesn't want them to just migrate away.
I mean the the whole cultural existence
of the Maldives will then will then disappear.
He wants to move the whole country someplace because this is coming.
This this is also from the Maldives.
This, this is them dealing with sea level on a daily basis.
Oh there was, in the National Geographic there was a beautiful
statistic that New Orleans is losing 44 acres per day.
That's a co- New Orleans, Louisiana,
southern Louisiana gets hit with a triple whammy.
Sea level's going up, there's there's tectonic depression
of Louisiana because when there was a big ice sheet in in Canada,
it pushed Canada down and pushed Louisiana up.
Well that ice sheet's gone so Canada's going up,
and it's kind of laughing at sea level rise 'cause it's going
up faster, but Louisiana's going down.
So you got sea level going up, got Louisiana going down,
and then all that Mississippi sediment,
Mississippi River sediment is consolidating.
So it loses on all three, all three scores.
And 44 acres are being flooded a day in southern Louisiana.
So, but let's look at it globally and the- and that's just in terms
of land area lost separated by continent
for a one meter rise in sea level.   Asia's gonna lose the most.
North America is actually gonna lose next.
But how 'bout in terms of population?
Asia, the big big loser.
And that's that's Bongaladesh, parts of India,
Southeast Asia and Indonesia.   And then, North America not so bad.
Europe was second there.
But in terms of the economic value, again Asia is the big loser.
Europe loses a lot.
The Netherlands figures in heavily here.
So i- you look it, slice and dice it different ways, one meter rise
in sea level is, well this used to be a lot, almost a trillion dollars.
But I can't say that's a lot of money anymore can I?
But for most of these countries it still is.
So it's it's a big, big, big, big, big deal.
Sea, rapid sea level rise must be from rapid
and sustained ice mass loss; no other way to get it.
But we've never witnessed such an event and I'm talking
about the really rapid stuff.
I'm talking not not 3 1/2 millimeters a year
but 10 mil- millimeters a year.
So what do, what we know we don't know.
We don't know how it happens; the actual processes.
We don't know if we can recogni- enough,
th- if we can recognize the early signs of it.
And so we're certainly in a position to predict,
as well as we would like, the future dramatic behavior.
So I'm I've eaten up most of my time here, I'm gonna have
to accelerate myself, but the prime culprit, I I have to talk
about this 'cause this is where the science gets really fun.
Prime culprit is, and I pause here just to give you a chance to see
if you can tell me, there there's a one word description
>> Warmth?   >> Wrmth, it's related to warmth.
I'm not hearin' it.   It's water.
>> Oh.
>> And so th- this is the fun part for a scientist, to talk about that.
Ice sheets hate water.
You know if you can remember four words--
I want you to remember a lot more than four words but,
remember these four words, ice sheets hate water, which just seems
so ironic because ice sheets are made of water right?
So, so but water is, feels hot to an ice sheet.
You know if you're you're getting ice off your windshield,
you know you want to pour mo- warm water on it.
Pour cold water on it-- it'll go away almost as quickly.
Ice hates water.
There's too much heat contained in, in water so.
Why does it hate water?
I'll give you a few reasons, but I've arranged these
in terms of rates of change.
And I'll start out with a slow one and not say much more about it.
It enhances melt, it makes snow darker, it, it absorbs radiation.
There's there's an amplification factor there but that's,
but I wouldn't be here and nobody would, nobody else would care
about ice sheets if that's all there was to it.
It can lubricate the [inaudible].   I'll I'll show an example of that.
It can actually break up ice shelve through a process of hydrofracture.
I'll show an illustration of that, and it can melt the floating edges
of ice sheets, these ice shelves, these big flat plates
and that's that's really the killer as it turns out, and I want to get
to that point so let me go quickly.
There is the, the atmospheric temperatures are on the rise
and we do see an increase in the in the extent of melt and the amount
of melt around the perimeter of the Greenland ice sheet.
That's contributing to the shrinkage of the ice sheet
but it's not the big player.
That water collects in really, in lakes and rivers
and finds its way into the ice sheet.
And you see in the lower right there, well you see on the left,
an actual picture of what it's doing.
And you see in the lower right, a a conception, conceptual illustration
of why it's infl- how it influences the ice sheet.
It finds its way all the way down to the, to the rock underneath
and then it flows along the interface and lubricates the ice.
And the reducing friction will allow the ice to flow faster,
and you can actually get rid of a lot more ice that way
because not only is the water itself leaving, which was ice before,
but it's but it's sort of allowing more ice
to flow faster into the ocean.
So there's an even greater amplification there.
And you see some numbers there, it can increase the flow rate,
you know, tens of percent.
Primarily in the summer because that's when you get the melt.
Hydrofracture is kind of, kind of interesting.
Here again we see this disintegrating ice shelf
in time lapse.
And so there are a lot of crevasses on on ice shelvs 'cause tha-
'cause the ice is stressed and is forced to move
in ways it doesn't want to and it cracks.
So we know about crevasses and that water obviously fills up,
flows into the crevasse.
But if you have an excess of water and it fills up the crevasse right
up to the top, if you think about the forces--
this is where the physics I I like comes in--
the forces right down here at the tip, the water's trying to open
that crevasse and it's heavy, and the ice is trying to squeeze
that tip shut and it's not as heavy.
So because water's heavier than ice, that tip will go down
and the crevasse goes deeper.
And as long as you can keep pouring water in at the top, that crevasse,
that crack will go all the way through.
So what's actually happening in this
in this sequence is you have water filling crevasses, and then once it,
once it separates into a whole bunch of tall, thin slabs,
those slabs fall over and that beautiful powder blue,
that picture that you see, you're looking at the color
of the inside of the ice shelf.
That's that's what the inside of the ice shelf looks like
and you're seeing it because it got chopped up with this process,
and all those tall, thin slabs kind of fell over like dominoes
that were standing on their tall end and then they fell over.
So, we've seen that happen, we've inferred that this is the process.
But even that's not the worst thing that can happen to an ice shelf.
The worst thing that can happen to an ice shelf is it gets attacked
by warm water that's in the ocean, and there's so much heat
in the ocean, the ice sheets don't stand a chance
if that water can get to the ice sheet.
And it gets to the ice sheet underneath these floating
ice shelves.
And this just illustrates that there's,
in the polar ocean it's cold on the top because of melting ice,
it's cold on the bottom 'cause that's
where the the cold water sinks to,
and it's actually warm in the middle.
And it's warm in the middle just off the continental shelf.
And if, it's it's really an issue of if that warm water can get
up onto the continental shelf,
then we jump to this illustration on the right.
It comes up onto the continental shelf and the first place it can get
onto the continental shelf are these valleys that were nicely eroded
by the glaciers themselves back in the last ice age.
And it's it's dense water.
It sits in this channel, and it just continues to ride down,
and it goes down because the ice sheet's heavy
and it's tilted the continental shelf this way.
So it's up in this channel and it just, it's heavy and just s-
just slowly flows down that channel until it hits the ice sheet.
And that's, for an ice sheet that's hot water.
That's a couple of degrees warmer than the ice sheet is,
and there's pressure and melting effects that come in
and just make it even worse.
So it melts like crazy, and when it melts is essentially this ice shelf
disintegration in slow motion.
And remember when the ice shelves disintegrate, the glaciers speed up.
So when the ice shelf gets melted and thinned,
the the the glaciers also speed up.
Not a factor of four and five, but a factor of 10 and 20 and 30%.
So this is this is what's hurting the ice shelves,
the ice sheets the most is that heat in the ocean that's that's getting
to the to the ice sheets.
And there's retreat that's goes along--
this is just amplification of that.
I'm gonna jump past that 'cause 'cause I do want
to illustrate some additional data as to why we know this is happening.
Here we have the s- the south, no the western side
of Greenland ice sheet in a whole bunch of different years.
And the color here is the temperature of the water
at the depths where the fishermen fish their cod or or other fish.
And they, they collected these data because they need
to know how warm the water is because it determines
where they fish and what type
of fish they they equip themselves to catch.
So from 1991 here, and there's '92, '93, '94, '95,
you know you you see the progression from year to year
of how the ocean temperature changed just off the coast of Greenland.
And I think you can see this this warm plume starting
up in these warmer colors, these red colors.
By the time it gets to this star, that's when that glacier,
that big [inaudible] glacier that I,
that was in the previous slide, began to retreat.
So the the sudden retreat of that of that,
all right I guess maybe I do need to show it.
It it took 50 years to retreat 10 kilometers.
It took another 60 years to retreat the next 10 kilometers.
It sat there for about 40 years.
And then all of the sudden is just took off.
In only fives it retreated another 10 kilometers
when that warm water entered the fiord.
The the two are are are linked together.
So we know that the ice sheet responds quickly
when warm water appears on the scene.
Okay so how are we gonna learn more?
I mean we we, we don't know anywhere near enough, and we're gonna have
to learn more by making more direct measurements, field studies.
Satellites have taken us a long way but, and helped point us
to where we need to go for field studies.
Analog studies is an important aspect.
I'll I'll show an illustration there what I'm talking about.
More field studies.   And numerical models.
And then more field studies 'cause, I'm sorry there's no substitute
for the direct observations.   And that's kind of bad news
because it's really hard to get these numbers.
I mean the ice sheets are, can be s- nasty places to work.
That's why satellite data are so, so popular.
For the analog study we'd go back to the tidewater glaciers.
I think we have seen, in observing how tidewater glaciers behave,
the future of the ice sheets.
Because we're, now we're seeing this happen around the margins
of the ice sheets, this drastic retreat mode
that that we've observed for tidewater glaciers in the past,
and illustrated here by the Muir Glacier,
is happening around the margin.
Just to illustrate why it's happening, you take a glacier coming
out of the mountains and it finds the the ocean there and it has
to get a little bit bigger to push that water
out of the way and displace the water.
And it and it moves material, moves marine as it as it slowly advances
into the fiord and it builds up this marine.
And you'll find a tidewater glacier terminus, the end of the glacier,
is actually in some fairly shallow water because it's sitting
on a marine that isn't made for itself.
It can't advance very rapidly because then it gets into deep water
and it calves back really rapidly.
So it can only advance slowly, and if it retreats off this marine,
then it then it changes its dynamics.
More ice is supplied to re-establish the terminus on this marine.
That's that's sort of where it where it needs to be to be quasi-stable.
But if it does retreat and it can't supply additional ice to re-advance
onto that marine, it gets into deeper water, calves faster,
retreats into deeper water, calves yet faster,
and this is this drastic retreat mode that tidewater glaciers are,
are designed for itself in in the nature of its advance.
And it'll continue to retreat until it gets either
to another shallow spot or
or in some cases all the way out of the fiord.
In the case of Muir Glacier, it's all the way out of its fiord.
So a tidewater glacier is either, either out here or it's retreating.
There really are no two other states for it.
I'll show you one video, I hope.   This this is a tidewater glacier.
It's calving.   This is not a gradual process.
That's about 10 D.C. city blocks worth there
that that just broke off.
It's, and and this is what people are seeing around the
around the margins of the Greenland ice sheet.
This is episodic.
A glacier will do this until it gets to another shallow spot,
and it'll get all the attention and it gets to the shallow spot,
and then it stops because it's mo- it's stable again.
Okay, one more.
Essentially see the same thing, just a big block.
That cliff's about 50 meters high and and the full thickness
of the ice is about six, seven times that.
So this, if you see James Balogg [assumed spelling] give give his
talk, he'll put little capitol buildings across there,
and little Washington monuments to give you a better sense of scale.
So Columbia Glacier is a tidewater glacier
and we actually studied this quite a lot.
Just just as I was ending my degree, I had the opportunity
to to do some work on this and you'll see sort of,
a a typical tidewater glacier in drastic retreat mode.
This is where the shallow marine is.
This is where the terminus had been for years and years and year
and in 1980 it finally lost its grip on it.
And in the course of 20 years it retreated about 20 kilometers
and in the year 2000 it was here.   Right now it's turned this corner,
it hesitated as it turned the corner, and it's going
to end up back here some time.
But I I show this because you see the glacier nicely,
you see open water here, and then you see all of this stuff.
It's called sikasook [phonetic] and it's that stuff
that was in those two videos.
It's just jumbled ice, and it's jumbled ice
because there's a glacier feeding it.
And it's stuck here because it's big chunks of ice that can't get
out because of that shallow marine.   It's stuck there.
So the reason for showing this is that that is the visual signature
of a tidewater glacier in drastic retreat.
And I've saved this other side of the slide
to show you a Greenland outlet glacier.
Exactly the same.
We know visually how to recognize a tidewater glacier
in drastic retreat mode.
And I invite you to go to Google earth and just march
around the perimeter of the Greenland ice sheet.
You will see this signature again and again and again.
You'll see a glacier.
You'll see all these, this this sort of whitish thing.
You won't see individual icebergs.
You don't, probably don't have the resolution to, but it's stuck there
because there is a shallow marine there.
That's a tidewater glacier in drastic retreat mode.
What do I want to say about this?
In Antarctica it's it's somewhat similar.
These, we think in Greenland they're triggered,
these drastic retreats are triggered by the warm water sort
of forcing the ice to lose its grip on these shallow marines.
In Antarctica it's a little bit different.
Here you have temperature of the water around Antarctica,
it's warmer where it's redder, and you see that it's in this portion
of the Antarctic ice sheet where the warmest ocean water is right
adjacent to the ice sheet.
It's not quite adjacent, there is a little continental shelf in between
but it's certainly closest there
and the ice sheet is most vulnerable in that area.
These big dots, these big red dots say that this part
of Antarctica is losing mass faster.
The size of the dot is how fast it's,
how fast it's mass is changing.   The red means it's losing.
So those line up and it tell us again that ocean is responsible.
This is what it looks like if you were there.
It's a it's a pretty dramatic place full of crevasses.
This is the Pine Island Glacier ice shelf and I show this because that's
where that red spot was biggest and where the,
where the ice loss is most dramatic.
I also show it because in a few months time, that's where I'll be.
We have a field project going there.
I mentioned the importance of the field measurements.
The British launched this fancy, automated submarine,
it went underneath the ice shelf and it found warm water.
Again, color here represents temperature
and the red is warmer water.
We found even some pretty warm water right here, that red,
little red tip is really, really important.
So it found it, it was a little snapshot.
Our field program is going to be going onto the ice shelf,
having a camp in the midst of that area I showed you,
and then drilling a hole and putting a profiler that's gonna go
up and down.
So it's not gonna wander around like the submarine did, but it's going
to sit there for a couple of years and
and hopefully capture this warm water and see how that changes
over time, and the cooler water coming out.
And get a, give us a different view as to what's going on underneath
because we need to get that information.
So just, this is gonna be the camp.
It's not our camp yet but it's gonna probably look something
like that 'cause the wind blows terribly.
A 50 knot wind is kind of a nice day on the Pine Island ice shelf.
That's parts of the drill.
That's the hole we're gonna make from a bore hole camera.
And then that's the profile that we're gonna put in.
So we practiced this in a place close
to McMurdo Station a few years ago so we're we're set to go.
It's a big logistic challenge but, but we're poised to do it this year.
Okay what can I say about the future?
I realize I'm running out of time here 'cause many stakeholder--
I should turn and bow towards congress whichever direction it is--
can't wait.   The IPCC weighed in on this,
that this is how sea level has risen during the last 150 years.
There's a slight increase in slope here, it is going up faster.
Their their published predictions were sort of this range here,
however they they admitted that they did not include ice sheet dynamics
which is about all I've talked about this this hour.
So when you, and you see where the one meter.
The the few papers that have tried through various means,
models and analog studies and and other methods,
to come up with an estimate for the, for the end of this century,
they all come up with bigger numbers.
And you can see the large range
because the uncertainty is still pretty high,
but they're all above this.
This is sort of a base and you add ice sheet dynamics it's gonna push
it higher.
In some cases, probably a lot higher.
And you see now I I I I hope you can appreciate why one meter is the best
number, and in general, likely a conservative number
for where sea level is going to be by the end of this century.
There are some estimates that that the entire range is above one meter,
but we have scientific discussions
about about the the rigorousness of that.
But one meter keeps coming up again and again and again.
This is just to say that it's not gonna be uniform everywhere.
Let me just skip past that and get to some good news.
It's not gonna happen tomorrow.
I have to be careful when I talk to kids about this they,
you know they go home and they cry to their parents
that you know they're gonna get flooded that that night.
So the good news is is it's gradual but it is inescapable.
We have to accept the reality of it
because we can plan gracefully for this.
The navy is very interested in planning gracefully for this.
The accurate projections are possible w-
with admitted large uncertainties, so we are providing th-
this information to to those of us,
to those who ask, those stakeholders.
And we tell them that we'll get better and better as we learn more
and more, as we get out in the field and make more measurements.
And and it, and it seems to make sense that the investment
in the science to to pro- to allow their
to be informed mitigation responses is a whole lot cheaper
than ignorance is.
Ignorance is, if you don't know what's coming, that's not the best,
not the best plan, we we humbly suggest.
So, conclusions.   I hope you I hope you get it,
that the ice sheets are, will continue to shrink.
They're shrinking now and they will continue to shrink.
And what that means for sea level is that sea level will rise
and the rate of rise will probably increase,
and that one meter is the best number we can give right now.
It's still, the IPCC is is in the process of writing its next report
and I lead one project and there are many other projects trying to,
trying to provide to to that group the best updates
on on our projections.
And that it affects people, hundreds of millions of people.
That's just first order.
Billions if you consider second order effects.
Ice sheets hate water.   Remember it.
And it's the warm ocean water.
That's where most of the heat is that's doing most of the damage
where the ice sheets respond most quickly.
And we're gonna get better at it.
If you want more there's some some websites here.
I I I'll just, I'll give my thank you slides, ask for questions,
and then come back to that if you want to get any of these URL's.
That PIG, that PIG Is there
because Pine Island Glacier spells PIG [laughter] so.
So thank you.   [ Applause ]
>> I gather we have questions, yes?   Sir?
>> When is the next ice age due to start?
>> Thousands and thousands of years from now.
Don't lose sleep over it.
So again that that really speaks to the time scale that,
we we think the ice she- ice sheets,
the whole glacial interglacial cycle was driven by orbital variations,
and so to the extent that that's true,
and most most scientists do buy off on that,
the next time things are aligned to nudge us towards another ice,
another ice age is at least 20,000 years in the future.
So a lot more is gonna happen in the next 20,000 years,
so it's kind of off the table.   >> No more questions?
>> So you mentioned this when you were talking about New Orleans
and how it changes the way the plates are moving
and I've read some things suggesting that that may increase earthquakes.
Can you [inaudible] to that?
>> Yeah I mean the question was whether the the tectonic adjustment
that has taken place, that I mentioned in in regards
to New Orleans might increase the the frequency of earthquakes.
Earthquakes is a tectonic phenomenon
so any time you start pushing plates around, either down, up,
or or to the side, y- you it holds the potential for more earthquakes.
I think in, I'm speaking a little bit out of my expert, well,
well out of my expertise-- I took a seismology course a long time ago--
but in general the the Midwest is is fairly, is not prone to earthquakes.
So changes in tectonics there are not likely
to increase frequency of earthquakes.
And again this is more a vertical change rather
than plates rubbing against each other.
So the places, it it's not gonna change I think
where earthquakes generally occur
and I doubt very much there would be an increase in the in the frequency
or or distribution of size of earthquakes, from that effect alone.
>> [Inaudible]
>> I think that I've read that once that the tidewater it,
or one that's got it's foot floating on the sea, once it retreats back
so that it's land based again
that rapid retreat slows down or or stops?
>> That's right, yeah.
You're asking about whether this drastic retreat mode stops when the
when the terminus of the glacier reaches shallow water again,
and and it absolutely does.   So it's an episodic event.
I mean I showed Helheim Glacier.
It received a lot of attention when it was in drastic retreat mode,
and then it hit another shallow spot, the retreat stopped,
and it got a whole bunch of other attention because it stopped--
aha don't worry about it-- but if, and that was right.
And it's starting to try to re-advance right now.
But then there's another glac- there are other glaciers around Greenland
that are sort of picking up the slack so, so it,
so that th- there's a, there's a lesson there.
Don't focus on one glacier
to read what the Greenland ice sheet is doing.
You'll learn about glacier dynamics doing that, but you won't,
but you'll miss the big story.
And so when you look at the big story,
Greenland actually is losing ice faster and faster and faster.
There are little blips in there
that represent individual glacier components to it.
So yeah that's a good question, thanks.
>> Sir?   >> Now this is about the time scale.
You said that during the last interglacial,
the ocean was five meters higher than it is currently,
but if all that stuff melted it'd be 65meters higher.
So I presume that means that during the last interglacial there was
still ice caps on Greenland and on Antarctica
but we read all these stories
about how once long ago there were you know palm trees
at the at the poles.
How long ago was it that the, you know all the ice caps melted off?
>> Yeah and and and your question about time scale's really important
because the last time that that palm trees were in Antarctica was tens
of millions of years ago.   So really long time ago.
The earth got into this glacial interglacial cycle
in the last few million years.
So it's been you know, going back and forth just just
in the last few million years.
So the palm trees in Antarctica are are a phenomenon that that occurred
when there was no ice on the planet
and it was really a whole lot warmer.
But that's a totally different geologic era
than the glacial interglacial period of time.
Yeah.   >> I thought we had one.
. .
>> [Inaudible] might be a little outside of the scope but,
how does what you do as a NASA scientist compare
to what the folks do over at NOAA in this area?
>> How is what I do as a NASA scient-
former NASA scientist compare to what's done at NOAA?
>> We we play in the same sandbox and our agencies force us
to to focus on on a little bit different perspective,
but many of the questions, these big questions, are the same.
And so we interact an awful lot.
In terms of satellite data, it doesn't matter to us
who collects the data whether it's whether it's something operated
by NOAA or NASA or ESA or JAXA or,
we we have to have our data you know wherever it comes from.
So I I think I think the differences
between the agencies become more distinct the higher
up the organizational chart you go and when you're down in the
in the working trenches like me, it it means very, very little.
>> What I've what I've heard
about what causes the climate change are the positions of the continents
when they drift apart and together, it affects the ocean currents.
So that would be like transport of heat from the equator north
and south via ocean currents and they change
as the continents move about.
The amount of carbon dioxide in the atmosphere
which has the greenhouse effect, but I'm wondering is there any evidence
that the sun itself is a, has a cycle of putting out more heat
and less heat and do we have enough data to tell, you know if,
if the output from the sun is constant as far as we're concerned
or is it, you know is it getting hotter
or cooler enough to change our climate?
>> Yeah yeah I mean, time scales again is is gonna be part
of this answer.
So the, you're asking about climate change and whether,
whether the sun plays a significant role in that.
It depends on what type of climate change you're talking about.
Like like the previous question, the continents moving around and and
and changing the shape and and of the oceans
and the ocean circulation, we're talking tens and probably hundreds
of millions of years for-- ago-- for that kind of process to be going on.
And yes, earth had a climate and yes it did change,
so yes that's legitima- legitimately sort of under the topic
of climate change, but but when we're talking about sort
of the climate changing right now,
it's it's a whole different set of circumstances.
Essentially the continents are frozen and it's,
and and they're not moving because we're talking
about a much shorter time scale in the here and now.
When it comes to the sun's influence, if if you go to the,
in the near term, the changes that have been observed and the trends
that are occurring now on say the century time scale,
the sun is not a player.
It do- there is some variability with sun spot, sun spot cycle,
but it's not, nobody's been successful
in correlating those variations with any variations
in the measured climate, any parameter in the climate.
But, it has gone through larger variations in in longer time scales,
and yes it does have an influence there.
So it, so the answer is it depends and you really have to be careful
when you say climate change.
What time scale are you interes- are you really focused on, so.
>> So what you're talking about is is attributable entirely
to car- carbon dioxide?
>> Yes. The the, a- and the other greenhouse gases.
I mean the the fact that I didn't get around to saying this
so this is an opening, so let me say it, that nobody's asked me yet how's
that warm, why does that warm water get
to the ice sheet now and it didn't before.
So, it's, it's a beautiful illustration
of how connected the climate system is, that with the warming
of the planet, Antarctica has managed to stay cooler than the rest
of the planet and has sort of its own climate if you will.
It's surrounded by an ocean that helps isolate it.
So it's it's stayed a little bit cooler than the rest of the planet
so you have an increase in that temperature gradient
between the rest of the world and and the southern polar region
and that increases the pressure gradient
and that increases the winds around the continent of Antarctica,
and it's that wind that moves the the water.
So you have the water sort of spinning faster and faster
around the continent and that's been measured.
And because it's the southern hemisphere, the coriolis force
for anything that moves will steer it to the left.
So it actually is pushing the surface water away
from the ice sheet.
Just the na- the nature of the circulation here in Antarctica
so that water turns away to the left, and what replaces
that surface water is water at depth.
We call it upwelling so so that that warm water essentially gets lifted
by the by the absence, by the absence of that surface,
the surface water going farther north.
And that actually lifts the warm water just enough to get it
into those, under the continental shelf where those valleys are.
So so that's the the linkages of processes
that we think are responsible for the the fairly sudden increase
of melting, the thinning on the ice shelf
and the acceleration of the glaciers.
It's it's that complicated.
>> We have time for one more and, neither one of you had [inaudible]
>> I'll be briefer [inaudible].
>> Are they q- okay, we'll do [inaudible].
. .
>> [Inaudible] you say something about the orbital variations more,
what's the nature of this?
Is the [inaudible] expanding and contracting
or what does that [inaudible] .
. . About the orbital variations, I would say th- it's
so many generations out you wouldn't,
I mean things change so slowly.   . .
>> [Inaudible]
>> Yeah, I mean I was gonna say how many generations
of grandchildren are you worried about and I was gonna say [laughter]
and I was gonna say that's not enough to matter.
This won't matter.   >> It does vary [inaudible].
. .   >> It does, but very very slowly.
I mean when when you show, when they show plots of things going up
and down look at look at look at the, look at the time axis,
and it's millions of years.
So so time scale, time scale, time scale.
>> Doctor, I was wondering [inaudible] on climate change,
as far as Greenland and the Arctic Circle, what is the position
of the United States on global energy resource and
and economic benefits and such?   Do you have anything?
>> The position of the United States in terms of climate change?
>> Climate change for their energy policy or energy.
. .
>> Well there are many positions aren't there?
[laughter] We had one question too many I think.
What's that?
But but this this is, I mean I'm I'm just speaking about what I know,
you know what I read in the in the paper.
Again this this is a, an opportunity to r- to remind you
that as a scientist I deliver the information
and I don't set the policy.
But as a citizen I would say it's it's very important
to recognize the reality of it and and to, and not bury our head
in the sand and I would encourage decision makers
to to take this information that scientists are providing
in all seriousness because I too have kids and I don't want to,
I don't want to, I want to deal with it as directly and as as immediately
as possible so that, 'cause it's only gonna get worse
if if response is delayed.   >>
[ Inaudible audience question ]
>> Yeah the, the scientists are working more and more closely
with with policymaking organizations in in lots of countries
because the whole geopolitical landscape in the Arctic
in particular is is rapidly changing and so countries are scrambling
to to try to realize that they need to know the best science
so that they can position, so they can act
in their own best interests most intelligently.
So so there there's some, there is an increase in appreciation
for this information in the US as well as other, other arctic nations.
>> Okay thank you for coming, and make sure to stop
by [inaudible] [applause]   >> Thank you.
>> This has been a presentation of the Library of Congress.