The voice of the water.
Sea level rise explained and understood.
Thinking of Holland I see slow streams slowly through infinite lowlands.
In 1936 Hendrik Marsman published his poem Reminder to Holland.
The most beautiful thing I think is the final rule.
In all regions, the voice of the water with its eternal disasters is feared and heard
I asked the engineers of Rijkswaterstaat how much sea level rise the Netherlands might have
Before it becomes uninhabitable here and the answer was The sky is the limit.
I had to think about the tower of Babylon.
So we can feel safe behind our dikes
But at the same time realize that it can go wrong once.
The Flood and the ark of Noah, the watershot of '53.
In the flood the word sounds sinful and I was therefore not surprised that the EO just broke the series Breaking the dikes.
Because I appreciate a nice disaster movie at the time I went to sleep well.
Great was the disappointment when I realized that the series was made from the point of view of human interest
And the disaster itself got little attention.
I watched it after a couple of minutes.
The engineer of Rijkswaterstaat was also critical of the series.
A storm that occurs once in the ten thousand years
Had broken the dikes just in a place that was strengthened by Rijkswaterstaat and made breakthrough free.
In Southampton I work with Ivan Haigh on flood risks.
And Ivan estimated that only 6% of the extreme high water levels coincide with an extreme storm.
When the dikes break, this happens due to a storm that occurs in the 600 years
But in the 10,000 years coincides with spring tide.
You must look at another part of the probability distribution of wind climatology
To estimate future risks on high water.
And those risks are increasing rapidly as the sea level rises.
What is still a high tide that occurs once in the 100 years takes place once every 100 years.
And in some countries like the United Kingdom, the future seems to have come true.
In the winter of 2013/14 and 2015/16
There was a "conveyor belt or storms battering the coasts of Britain"
As the BBC's weaver has said beautifully.
In the Netherlands we have better deal with our business.
We are the only country in the world with a national health care system.
We had to laugh at home when Prime Minister Cameron announced in 2016
To invest millions to avoid flooding like in the past winters in the future.
That had to be billions of course.
What England needed was a Delta Commissioner with a Deltaplan.
Last year I visited the Seventh National Delta Congress.
The left front leg on which this chair stands is the connection between science and policy
And hence I was in Apeldoorn that day.
The motto of the conference was Together on price.
And I heard the beauty say that we want to make the Netherlands water-resistant and climate-proof
And I thought Oh and for how long?
Even if we can stop global warming today
The sea level continues to rise for a few thousand years.
That science also tries to find its way to the policy.
There we have the National Knowledge and Innovation program for Water and Climate in the Netherlands.
I was talking to a dike dig.
The dike grave did not believe in climate change.
He suggested that there was no acceleration of sea level rise for our coast.
Since 1865, the sea level has increased steadily and only by 20 cm.
I gave it equally equally, but I answered, on average, that acceleration is true.
In some places, the sea level rises much harder than in other places.
He watched me infidelity. That can not be true, he cast off
If you are middle of waves and tides, the sea level is the same everywhere and indignant, he walked away.
The dike grave sees the world sea as a waste dump.
That wastewater fits a flat motionless earth.
And while there are still surprisingly many people in the belief that the earth is a flat disk,
I assume we can skip that step here.
Even with a spherical earth, we can imagine that the sea level is flat.
Now a spherical surface. Only the earth is no sphere.
We can imagine more complex geometries that fit even better with the shape of the earth
But the earth knows mountains, valleys filled with oceans
Lighter and heavier rock that is inhomogeneously distributed over the surface and deep below it.
In all cases gravity determines the shape of the sea level.
And the gravity on earth varies from place to place, depending on whether more or less mass is below the surface.
If you travel from Barcelona to Istanbul, you are about 100 meters down
And climb back one hundred meters to the center of the earth.
If you move the Himalayas to Germany, Amsterdam is tens of meters underwater
Only because of the increased gravity that pulls up the sea level.
Using satellites, we can determine the shape of the sea level at a sea at rest.
We call that shape the geoid and nowhere is the geoid level.
He looks like a wrinkled potato.
Also, the sea level is almost unrelated to the geoid.
We have not yet processed the influence of flow and rotation.
And I can illustrate the effect of the two with a teacup.
Sprinkling with a spoon creates a whirl.
The mirror is the lowest in the middle and the highest at the edge.
The revolving tea is pushed out by the
Centrifugal force but can not escape the head.
There must be an opposing force pushing the tea in again.
The pressure difference between the edge and the center of the cup, or the difference in the mirror.
On a revolving earth, the Coriolis force takes over the role of centrifugal force
Both depend on the flow rate.
If the flow becomes stronger, the pressure difference in the liquid must also be increased.
This is reflected in height differences in the sea surface.
Lines of equal sea level are the isobars on a weather map.
Flow and wind flow parallel to those lines and where they are close to each other, the flow is strong,
Where they are far apart, the flow is weak
A low sea level corresponds to a low pressure range and the same applies to high.
The pressure differences arise due to differences in temperature and salt content in the water,
Caused by variations in wind and heat and moisture exchange with the atmosphere.
There are also differences between Corilis power and centrifugal force.
The ocean has hollow and convex vertebrae depending on the direction of rotation and the hemisphere in which we are.
A chart of the sea level trend over the past few years shows that in many places the trend was greater than the world average trend of 3 mm per year.
And that in other places the trend was even negative.
Locally, over a period of less than a century, the trend is mainly determined by fluctuations in wind precipitation and temperature.
The map of recent years is a reflection of the effect of the negative phase of El Niño
An El Niño at the beginning and a La Niña at the end of the measurement period
With warm water and high sea levels in the western Pacific and Indian Ocean
Cold water and low sea levels in the eastern Pacific Ocean.
Some statisticians believe that the best model for predicting sea levels in the future is to extrapolate the current trend.
Applied to these data we would expect a growing La Niña
Ultimately ocean currents of tens of kilometers per hour and tsunamis destroying the coasts of the world.
But past performance does not guarantee the future.
The patterns on a trend card are predominantly determined by fluctuations that change in their opposite years.
What does this mean for the Netherlands now?
Over the last 20 years, the sea level for our coast has risen below average
But in the middle of the North Atlantic, stronger than average.
In the west of Ireland, a huge swirl runs around the ocean and the North Sea is on the edge of that vertebra.
Like the tea cup, it means that the sea level in the North Sea is high and in the middle of the vertebra.
But the sea level in the North Sea and those in the middle of the vertebra whip a little up and down
As the vertebra turns slower or faster.
And the vertebra turns faster when the water in the middle becomes colder and vice versa.
For the last 20 years the vertebra was relatively hot and weak
But now it seems to hit cold and strong.
I therefore predict an additional strong sea level rise on the Dutch coast for the next 20 years.
Regional sea change is the right front leg on which this chair stands.
Together with and especially by colleague Dewi Le Bars, we have set up a model for the European coast at the KNMI
And the agreement between the monthly average sea level variations in the model and in the observations is incredibly good.
I hope we can make predictions and projections in the future soon.
The third and fourth leg of this chair have to do with the ice-cream of Antarctica.
But I can only explain the third leg if I showed something of the fourth leg.
I start with the temperature spiral designed by Ed Hawkins of Reading University.
It shows the temperature deviation per month over the period 1850-1900 per month.
Last year we passed the 1.4 degree,
Which places the agreements of the Paris climate agreement in a certain context.
Geological observations show that the relationship between sea level and temperature rise for a climate that seems to be about 6 meters or a degree today
We already have 1.4 and only 30 cm sea level rise.
What's up with that?
The sea level rise in recent years is mainly due to the expansion of warmer water and the melting of small glaciers.
The extra meters that are still in the vessel come from the ice caps and respond with delay
Until recently, we thought that the reaction time of ice cream was over a thousand years.
But the ice caps appear to respond much faster
In many places ice caps are surrounded by ice shelves
Floating ice sheets stabbing the ice cream like supporting a cathedral.
In the transition between ice cream and ice sheet, land ice is in contact with sea water.
And water conducts heat much better than air
And melt from below is the biggest threat to Antarctica.
But where comes that warm water with -1 degree celsius
Still as hot as compared to ice melting water actually?
This brings me to the left hind leg of this chair.
That hot water comes from the north but how it gets under the floating ice sheets is a mystery.
The flow follows lines of constant sea level and thus circles around Antarctica.
That hot water should be brought to the Antarctica perpendicular to the flow.
How does that work?
The wind pumps that bring warmer water as a sub stream from the warm Gulf Stream to the Southern Ocean
About 1000 km from the coast
But most of the water is driven back to the north by the wind.
Many mechanisms have been devised to explain how part of that water comes to the ice creams
But in our climate models, those processes do not work.
There is a heat front on the continental slope of Antarctica
And the warm water stays neatly behind the front.
An important process that can not reproduce climate models is the formation of vertebrates of 1 to 10 km in diameter
Which mix the hot water across the front.
With a model of the Antarctic Slope Front
10x as fine as the finest climate model,
We simulate vertebrae that mix warm and cold water, but it does not prove enough.
Other processes must also play a role
Katabatic winds pouring down the icecream
And to cause a north-south flow in the ocean not properly solved in climate models.
Mixing of tides not even included in climate models.
Deep canyons in the seabed that can lead the hot water under the front.
Those canyons are everywhere but because the seabed can hardly be mapped under the floating ice sheets
Are they not present in our database of the seabed.
Also, we are interested in temperature fluctuations in the water of the ice cream
Is that water so hot due to the greenhouse effect or there are also natural variations
Many models show a 50 to 100 year fluctuation between seawater temperature around Antarctica and in the North Atlantic Ocean.
In the ocean model of Utrecht University, this fluctuation is controlled by processes in the Southern Ocean.
There is the outlet for the swing.
However, in the KNMI climate model, this fluctuation is controlled by North Atlantic processes and sales take place in the north.
These fluctuations are so slow that the observations can not yet give an indication of where the sales take place.
The fluctuation in temperature of the water near the coast that is in direct contact with the ice caps is about a 10th degree.
10, which seems at first sight nothing but 0.1 degree difference in sea water temperature in the deep southern ocean can completely change the face of the world.
The right back leg of the chair is the instability of the Antarctic Ice Cream.
If you move the Himalayas to Germany, only by changing the gravitational force of Amsterdam will be tens of meters under water.
If we change the mountain of stone in ice in our thought experiment that slowly begins to melt
Then Amsterdam is slowly dry
Because the gravity decreases on the ground and the geoid drops down
While the sea level in the rest of the world must rise due to all the melting water that comes with it.
The turnaround between bags and ascents is 2500l km away.
For this reason, we do not mind much in the Netherlands from melting the Greenlandic icecream
But of Antarctica all the more
Last year, the scientific world was frightened by a US study with a ice cream model incorporating two new processes that had been overlooked until now
And which could increase the rate of sea level rise to 6 cm per year in the beginning of the next century.
The Wadden Sea is already disappearing if the sea level rise rises more than 1 to 2 cm per year
In this scenario in the second half of this century.
What are these new processes?
I start with a process that can simulate all ice cream models today but which have not yet been taken into account in the last IPCC report.
Marine Ice Sheet Instability MISI
If the sea water gets under the floating ice sheets, it also melts more land ice.
The point where floating ice hits the ground and land ice becomes the grounding, line then moves inland.
In places where the bottom is down, the amount of ice above the grounding line increases in that case.
And this is the case in West Antarctica.
Now the outflow from land ice to drift ice is proportional to the thickness of the ice layer above the grounding line.
So as the bottom slopes down and the grounding line starts moving inland
Increases the flow of land ice to drift ice, which causes land ice to lose more mass
Increasing the grounding line further inland, increasing the flow of land ice to drift ice, etc.
This self-strengthening process is initiated when a so-called tipping point or tilt point is passed.
Recently it has been proven that this is happening at the Pine Island glacier in the Amundsen Sea at Antartica and probably in a few more places.
The process is only very difficult to demonstrate, but it has been successful with drilling through the ice sheet into the seabed.
It was concluded that an El Niño had initiated the process
And that the process continued only after the seawater had cooled down when the El Niño was over.
You have that variation of a 0.1 degree still in mind.
The plate was found to lose 500 m thick but 20 m per year.
The Antarctic icecream rattles bump off.
The two most northerly ice sheets Larsen A and Larsen B,
Something east of the Antarctic Peninsula has now collapsed.
After the disappearance of those ice sheets, the outflow of land ice to the sea increased by a factor of five
The disintegration of a floating ice sheet is caused by the fact that hot air melts and cracks leave behind
Soaking the water down and eroding the ice.
The technical term for this is hydrofracturing and the warmer it gets the more often it occurs.
Two Americans added theConto and Pollard
This process accelerated enormously to their ice-cream model and the demolition of Antarctica.
Other scientists have argued that this process would not occur on the more southern ice sheets this century
Because it's too cold and remains for the time being.
But satellite imagery proves the opposite.
Melting plants are found everywhere, even in East Antarctica where nobody thought they would be sitting.
Last week there was an article that estimated that more than 1000 X is present on the ice sheets and on the edge of the iceberg so much melting water
As calculated by the best regional climate model of Antarctica.
The underestimation in the model we understand, but the factor with which is gigantic.
What is going on?
As we see, new cracks arise in various places.
At Larsen C is currently developing a hundred kilometers long and hundreds of meters wide crack that threatens to break the record.
The plate breaks out ever more and yesterday it became known that the front of the crack is only 13 km from the coast.
A warning has been issued to all ships in the vicinity that breaks down a huge ice sheet within a few weeks, resulting in huge waves.
Whether this is the forerunner of Larsen C's complete breakdown is still unclear, but it does not look good.
Also, the ice sheets appear to tear down from the bottom.
These basal gaps are sometimes hundreds of feet deep.
A process that was not included in the American icecream model.
A second controversial process in their new model is Ice Cliff Instability ICI
Above the grounding line, land ice cream is floating in a floating ice sheet
But when the ice sheet breaks up, a cliff rises above the grounding line.
And too high a cliff falls under its own weight.
On land landslides on cliffs are universal.
The equivalent ice shift is accompanied by much larger chunks
But the process is the same and has been observed on the large ice caps in a few places.
The critical height for ICI is 80 m above sea level.
DeConto and Pollard have estimated how quickly this process breaks down a icecream.
If you take that process along, you can not really lose hell in their model
Many scientists find that ICI is still not known enough to model it
And that the two gentlemen were out of sensation; A publication in the journal Nature.
Undoubtedly true.
But the Americans dispel that their estimation is still on the conservative side and that without this process the geological sea level variations are not imitated.
The last word has not yet been said.
Their new projections of the sea level rise for the end 2100l amount to more than 1 m
Only through Antarctica and even 6m in 2200.
It is a worst case scenario
CO2 emissions are not reduced for 2200 but still
And for the Netherlands another 20% Because of the gravity effect.
If you also charge the other processes, the probability distribution for the total sea level rise according to the IPCC scenario
And the worst case scenario of the account and pollard totally different.
They are both valid within the limits of their own assumptions.
But at the same time they close each other and how to connect those two does not know anyone yet.
In a policy hackathon where a group of employees tries to crack a policy issue
More than 20 employees from Deltares considered the consequences of extreme sea level rises and the possible measures to limit the impact on the Netherlands.
They confirmed the image of the Rijkswaterstaat engineers
That there are no fundamental technical barriers that also prevent adequate coastal defense.
But there is a price tag. About 500 billion.
And the accompanying measures will make the Netherlands a totally different country
Dunes and beaches migrate inland.
The upward pressure on groundwater begins to burst the coating on which we live and work.
Groundwater. The drop of altitude difference between Lobith and the sea,
Requires huge pumps to get rid of the Rhine.
The river drain must pass through the IJssel and the Gelderse valley to the IJsselmeer.
Higher dikes become proportionally wider and quadratic more expensive, ports and farmland disappear.
And with the current rate of dive replacement, we need to think ahead for 125 years.
And now taking into account the sea level rise in the mid-century century.
If we take that all for granted, there are three options left:
A walled fort of the Netherlands with huge pumps,
Or extremely deep rivers with ever higher dikes,
Or let the low-lying areas run with a few cities on terriers.
It seems science fiction, but the discussion that the Netherlands has to go must actually start today.
With Bangladesh, Suriname and Guyana we belong to the 4 countries
Whose population, if we make the switch to renewable energy in 2100,
To live below 75% below sea level.
And not only the Randstad but about 30 mega cities with more than 10 million inhabitants will become uninhabitable without extremely expensive measures.
The question for science is: how quickly and how much is the risk of these kinds of scenarios.
But when I last introduced a colleague, the accounts of the Account and Pollard in our
To study their own icecream models was the response:
I do not currently feel like testing Antarctic disaster scenarios.
Was I an evil prostitute? Someone who swallows in calamity and misery?
Does the right rear leg of this chair stand on ice-cream?
In an interview following his Bible for unbelievers
Author Guus Kuijer said that prophets are the worst battle people are in the Bible
Prophets believe to have the truth in mind
And close others or kill them if they do not add to that truth.
The true heroes of the Bible are people who are the
Truth not to be in charge but to seek the truth.
So scientists!
I felt restured, but still something went wrong.
Old prophets heard the voice of God, maybe new prophets, the voice of the water.
Everyone knows the song "When Jonas was in the whale"
With someone on the left forehead holding the right front leg to the left and right hind legs
A few times back and forth sling and release huppetee.
Jonah is my favorite pro.
He does not fit into the category that Guus Kuier despises.
Jonah came from Ninevé, a city in the low-lying delta between the Euphrates and the Tigris
And he was wearing a climate dynamics chair.
With his scenarios for sea level rise he was laughed by everyone.
But Jonah did not discourage it.
Human interest was not his thing.
Every day he sought the truth, and in that capacity he spoke to God.
But on an evil day, the roles turn around.
God wants to speak to Jonah.
He is still disappointed in humans and in Nineveh's most.
As a punishment for sin, God intends to undermine the city with a flood.
Jonah gets forty days to turn off the disaster and convert the people.
That does not matter, he spits against.
I'm not taken seriously by anyone.
You are doing your best, but God answers.
And, reluctantly, Jonah begins a public hearing
And pulls with his powerpoint from hall to hall.
But everywhere he is run away.
On the fortieth day he installs himself on the Utrechtse Heuvelrug where he has a good view of the delta.
He's going to sit well for it, because Jonah knows how to appreciate a great disaster movie.
But at sunset there is still nothing happening and indignant, he tests the familiar number.
You basted me completely.
7 meter sea rise you promised me and I have not seen a centimeter of it yet.
The people have repented to answer God.
They have signed an agreement in Paris.
A declaration of intent to limit the world average temperature rise to 1.5 degree.
And you believe that?
We are already at 1.4!
How do you think they are going to do that, asks Jonah disbelief.
That is still being sought, God says, but the first step has been taken.
Yes, yes, the road to hell is paved with good intentions, Jonah opposes
There I know everything about answer God.
But Nineve's people deserve a second chance.
Jonah is furious.
Immediately he checks the number of the National Oceanography Center
With the question of whether they still have a chair.
That is the case.
And the next day he goes to Southampton.
That night is the storm that breaks the dikes once in 10,000 years.
But in the middle of the night the storm is moving its course.
Jonah is awakened by the captain.
I have never seen such a sea and you are an oceanographer, says the captain
Tell me how to get out of here.
Jonah shakes his head.
This is the perfect storm he answers. There is no way out.
You're just unlucky to take me on board because the storm has hit me.
Some sailors who listened to the conversation think that there is indeed a way out.
The first takes Jonah to the left forehead, the second at the right forehead, and so forth.
Jonah goes overboard.
Regardless of the storm that occurs once in 10,000 years,
Or by global warming or that it was a pre-planned plan.
But a whale on the way to the Polish Sea takes the wrong exit between the Orkney and the Shetlands and swims the North Sea.
After Jonah has been aboard, he ends up in the mouth of the planktoneter who lovingly returns him to the coast.
As I said to you, the whale speaks against him
Everyone gets a second chance at me.
A year ago we installed an icecream model from Antarctica in Southampton.
That model is driven by atmospheric fields of the model known as RACMO.
Almost one million numbers.
But for the ocean, only one parameter was available.
A constant seawater temperature, uniform for the whole continent.
That should be better, I thought, and I asked my programmer Jeff Blundell to add that parameter to time and place
So that the graduate student could investigate what happens when seawater warms up
And what if the seawater temperature also varies from year to year.
It turned out months of work for student and programmer to change the model code.
Time for Plan B.
We kept T (ocean) constant but left in each new run the sea water temperature with you recommends increasing it by 0.1 degree.
With a temperature of -1.7 below the floating ice sheets and the RACMO atmosphere today
The Antarctic Ice Cream is now imitated.
If you make that ocean temperature -1.6 you get almost the same ice cream
Also with -1.5 nothing is going on.
But at -1.4 we have more than 2 meters sea level rise for the pick and at -1.3 degrees even more than 7 meters.
Then there is a plateau.
First, the ice cream is insensitive to a temperature rise.
Then there is a tipping point where a change of 0.1 degree or less is enough to cause something tremendous
And then there is an interval where the sensitivity of the ice cream is small.
7 meters sea level rise means that the entire West Antarctic icecap is lost
By a little bit of ocean warming.
Without the need for further warming of the atmosphere.
Even the COP21 agreement can not stop the disappearance of the West Antarctic icecap.
But the rate of degradation depends critically on the rate at which COP21 is performed.
If the ocean starts to get warmer, the ice cube degradation begins at two places in the model.
At the Filchner-Ronne ice sheets at the ice sheets in the Amundsen Sea
And a little later at the ice sheet in the Ross Sea.
But in reality, the seawater in the Amundsen Sea is much warmer than the other ice sheets
And even a bit warmer than at the turning point.
The ice sheets there are already disappearing and are doomed.
But the Filchner-Ronne and Ross Zee tipping points have not yet been reached.
The 7 meter sea rise through Antarctica takes place in three steps
And between the first step of 1 meter and the third step from 2.5 to more than 7 meters lies our second chance.
And there's even a third chance of damage control.
We can greatly slow down passing those other tilt points.
The extra chance and the extra chance lies in the nature of the laws of nature
Or in the mathematics with which we describe and intend to understand nature.
And whether that is a coincidence, or something has been written by someone or someone may make each one a separate one.
But the second chance is universal because the universe is full of systems with multiple tilting points.
The message I want to give this afternoon to the politicians who are trying to conclude a new government agreement
To the policy staff of the ministry of I & M
And the staff of DG Water, members of the Delta Commission and your wealthy citizens with their own voice
In which once in the 4 years and sometimes the voice of the water may sound together
Is: "Grab that opportunity"!
Otherwise, much of this country has more history than the future.
I have said.