Klimawandel – Was die Wissenschaft wirklich weiß (…und was nicht) | 1/2 | WDR Doku
Good that you are here No really thanks for taking the time to talk about climate change because it seems like you, I’ve heard it all 2018 went down in German weather history as a record year. 2020 was the second warmest year in Germany.
According to this, climate, change is already hitting Germany harder than feared.
Climate change is increasing from a trot to a gallop and is approaching points at which even drastic greenhouse gas savings can no longer prevent serious consequences.
What you also hear all the time is really behind the science, It is always said that climate researchers agree.
But what exactly do they agree on? Not at all, listen to that Our handling of climate change is like a collective suicide attempt, says Hans Joachim Schellnhuber, who advised the Chancellor and the EU Commission on climate issues, among other things, To speak of collective suicide.
Is unscientific, says this man, and warns against alarmism.
Hans von Storch, received the Federal Cross of Merit for his climate research, 2 renowned voices, 2 different voices Honestly between us.
I am also one of those who have always put the scientific consensus in the foreground, But now I think, maybe that’s oversimplifying So let’s take a closer look today.
What does climate science know V? How does she know that And what doesn’t she know? I’m pretty sure you’ll have a whole new understanding of climate change after this, So we rolled over studies, We spoke to experts, including those who are otherwise not noticed in public, And not only that Hello.
I’m Caro and I was on the road for you. I was on an alpine glacier that is melting at record speed, But it was also smaller than it is today.
I’ve been to climate researchers who rave about their supercomputers and their climate models, but also speak openly about their limitations.
I was in a veritable treasure trove.
Why does it have to be so cold here And I’ve been where a lot of people are wondering what it means for them if the sea level rises, But first back to May Make yourself comfortable.
This will take longer.
But after that you know climate change, What science knows and doesn’t know: August 2020, a field near Bergheim, west of Cologne, It’s 36 and it’s going to get even hotter.
This weekend It’s, exhausting even for old people.
It’s, exhausting for everyone who has to work in this heat, And it is above all, a problem for farmers.
Yes, should we take a look at the whole thing on site? Yes, gladly.
I’m with Johannes Hensen. His family has been farming here for generations.
However, in recent years they have been struggling with a particular problem.
Johannes, We have an extreme irrigation effort Without water, the potato would consider dying.
What does it mean for your everyday work that it is so hot and dry To make a long story short? I have 4 to 6 hours more per day for my extra work.
We have about 25 euros an hour for electricity alone And in the last 10 years, roughly 0 5 million were invested in irrigation.
Is this a normal summer or has it increased over the past few years? The drought has been around for about 4 5 weeks.
The heat makes the drought worse.
The land rain from before is missing.
Is that climate change There have been hot days and hot phases before But the intensity.
I e The intervals are getting shorter. The hot and dry phases are coming faster, one after the other.
Maybe longer than before, You can call that climate change, But it gets more extreme.
The question is: is that still weather, or is that already climate? You may have asked yourself this before. Are a series of hot summers already evidence of climate change Or a snowy winter? A sign that it’s, not that bad after all, Let’s put it this way.
Weather and climate are two different things, but they are closely related.
I want to find out exactly how weather and climate are related at the German Weather Service in Offenbach With Matthias Fuchs.
What is climate, what is weather Weather is the here and now That’s all We all know that from the weather forecast, We have to wait a long time for climate.
We have to measure for at least 30 years and then have to evaluate this measurement data for each location, See how changes in temperature, precipitation, air pressure, and sunshine affect these places.
Can you tell me, has it gotten hotter and drier, or is it just a feeling? We at the German Weather Service can’t work with feelings, but I’m happy to explain that to you in more detail Here we see the annual mean temperatures in Germany in all regions from 1881, then plotted every 10 years up to the last decade.
From 2010 to 2019, Blue means too cold.
Red means too warm. Okay.
There were a few red ones here too, and a few blue ones here too, But the trend is already clearly visible.
Why did the German Weather Service collect reliable data? Well, we have the most data and the best data for temperature.
This is simply because it is the easiest to measure.
We can say relatively clearly that extremes are changing, that they are increasing Our wildfire hazard warnings.
You can see that there is an increase in the data.
We see it very clearly in the heat waves, It’s a bit more difficult with heavy precipitation because rain falls very locally.
The rain radar which we have been using in the weather service for 20 years now helps us a lot Okay, so you still have 10 years to go before you can talk about climate.
Exactly we only talk about climate from the age of 30.
In this respect. Indeed, yes, 10 years are missing By the way.
Today there is a dense network of measuring stations whose data the German Weather Service can access, But that wasn’t always the case Were the measuring devices precise enough back then, Especially since it is about deviations of sometimes tenths of a degree?
In other words, is it even possible to compare the data from today with that from 100 years ago? Dirk Windm ller shows me how the weather is measured today. What does a weather station look like Exactly, and this is one of 180 full-time weather stations of the German Weather Service. Not that spectacular, But only at first glance I didn’t know what was measured and how Here they measure visibility in fog, cloud height, air pressure, sunshine, duration, wind amount of precipitation, ground temperature, and much more with digital precision earlier.
Yes, what we have here are measuring devices and antique measuring devices.
It must be said that were used in the last century.
With this ball, you could measure the duration of sunshine using the burning glass effect.
The other one here is a radiosonde from 1935 that measures, temperature, and barometric pressure, this hand, held device.
The wind speed was determined Awesome, partly from the 1930s Wasn’t that inaccurate One would like to think so, but it wasn’t actually like that.
Only the methodology has changed.
Can you prove that The German Weather Service has been using climate reference stations since 2008, Older and newer generation measurement technology is used at these stations. The measurement data are compared and we hardly find any differences. That means you can make statements.
You can compare the values, hen and now and d termine climate trend.
Of course, measurements were not only taken in Germany but all over the world.
Globally, the measurement series show the same trend, Namely compared to the time before industrialization.
It has meanwhile become warmer by more than 1, So there is nothing wrong with these measurements.
We can already say that it has gotten warmer Just.
Why is it getting warmer Greenhouse effect? We’ve heard it a thousand times, But what exactly does that mean? So the greenhouse effect itself is much older than us humans.
Without him, we wouldn’t exist at all A tiny part of our earth.’s atmosphere less than 0 1 consists of greenhouse gases.
The most important are water vapor, carbon dioxide, methane, and nitrous oxide.
Greenhouse gases – don’t give a damn about solar radiation. The radiation is too short a wave for that When the sun’s radiation reaches the earth, part of it is reflected.
I e radiated back A part is absorbed.
E taken in any part of this absorbed radiation is also reflected, albeit in the form of long wave radiation in the infrared range, And that is precisely the range of wavelengths that greenhouse gas molecules can capture The infrared radiation causes the greenhouse gas molecules to Vibrate and is thereby converted into heat, So stay in the atmosphere and that’s good for now, Without this greenhouse effect, it would be 32 cooler on average on earth Which is uncomfortable.
You can see what an effect such a touch of greenhouse gas can have By the way with such a greenhouse.
That is a greenhouse.
We have a different heat effect.
First and foremost, it gets warm here because the warm air has nowhere to go.
This is not the case on our earth, Which is why the name greenhouse effect is actually, how do you say it physically and metaphorically, pretty stupid.
In any case, it is physics that the more greenhouse gases we have in the atmosphere, the warmer it gets.
So there is no question about this connection either, But how do we know that greenhouse gas concentrations are increasing To clear that up? I’m going to a very special place in the Austrian Alps With a cable car that ordinary tourists are not allowed to use. Only the Sonnblick Observatory staff Doctor Elke Ludewig manages the measuring station high up at over 3 100 m.
What a job You can see the M local Glacier the Lienz Dolomites, and the direction of Carinthia to the side.
The observatory on the summit of the Hoher Sonnblick has been there.
Since 1886.
We only had a 4 day break after the First World War when the military withdrew One of the longest time series in the world.
We are lucky with our visit.
The summit is called Sonnblick, but it is in the clouds for most of the year, But there is something else that makes this place so special for Elke, Ludewig, and climate research.
So here we have, for example, the heart of our climate research station up here.
This is the intake for the CO2 measurement.
It works like this. It’s a chimney that sucks in the air and doesn’t blow it out like normal and then leads the air to the meter That’s, probably pretty unique Or how many measuring stations are there that measure CO2 values?
It’s a special facility because we’re up here in the free atmosphere.
There are currently 40 stations measuring in the Global Atmosphere Watch Program.
This measured value is comparable e g with the measuring station in Hawaii on Mauna Lou.
These values are compared able, Plus what’s special up here is that we’re in the great outdoors.
We hardly have any tourism up here.
Everything runs on electricity here We don’t have diesel generators.
This allows us to measure the climate value, the CO2 climate value in the atmosphere.
If we stand here longer and breathe out, the devices are so sensitive that they notice.
Then we get a peak that our CO2 emissions are recorded by a measuring device away quickly. I don’t want to be responsible for a higher CO2 value, But I’m curious to see how the CO2 value has changed here in recent years.
Here we are in the air chemistry lab.
This is the connection at the top to the chimney.
This is where the air comes in and on this monitor, you can see the readings from the last few hours.
This is minute data That’s.
Why? It?’s bouncing back and forth If we take monthly averages and line them up, we see a curve that has an annual variation, and seasonal ups, and downs, But the trend is strongly upwards.
Let’s take a closer look at this graph.
Co2 has been measured at Sonnblick since 1999, and the curve has been rising since 1999 By the way if you are wondering why there is a hole here, there were technical problems in 2011, the measuring device failed, But the red line climbs, and climbs from 370 PPM In 2000 to 413 PPM in November 2020, By the way, PPM is a unit of concentration, stands for parts per million.
I e particles of CO2 per million particles of air, But we don’t have to rely on the Sonnblick Observatory.
There is a global network of measuring stations in remote locations where CO2 is measured in the pure atmosphere. There we see that the comparative values on Mauna Loa in Hawaii look the same And by the way CO2 has not only been measured there since 1999 but since 1958, So and that was just CO2, There are other greenhouse gases – e g, the particular climate, impacting methane, Which cows like to fart out All greenhouse gases are often combined and converted into CO2 equivalents.
Overall, the value of all greenhouse gases in 2018 was 496 PPM CO2 equivalent, And what does 496 PPM mean now Well? According to the Intergovernmental Panel on Climate Change, a limit of 450 PPM must not be permanently exceeded if we want to limit global warming to 2.
This means that if things continue as before, we will miss the 2 targets And the timing and timing of the warming align very well with the industrialization of the Earth.
Since the beginning of industrialization.
The CO2 content in the atmosphere has increased by almost 50.
So, just because industrialization coincides with global warming, doesn’t automatically mean that industrialization is the cause.
Don’t, you always preach.
That correlation is not causation.
How can we be sure that climate change is man-made With chemistry? The CO2 that comes out of our factory chimneys is chemically different than the CO2 that you and I exhale, Because a tiny part of the carbon atoms.
I e The C atoms that make up my body and my breath are C14 isotopes or C14 atoms, And it is precisely these C14 atoms that are missing in the CO2 from the factories. But what is this? C14 C14 atoms are special carbon atoms that are radioactive.
Yes, I know what are radioactive atoms doing in my body, And where are they from? They come from the atmosphere, because that’s, where C14 is formed by cosmic radiation and sooner or later, ends up in all living things.
Plants absorb C14 from CO2 and incorporate it into their leaves and stem through photosynthesis.
Humans and animals eat plants and humans and animals also eat each other.
Of course, people don’t eat each other.
I hope Please, don’t eat people.
That is why all living things contain a tiny fraction of radioactive C14 atoms.
So if I die now, but if I die dear friends, I want you to know one thing, Namely that the radioactive C14 will decay in my body, And since when I’m dead, I won’t be able to eat or breathe anymore.
So I won’t take any more C14 either And at some point, my body will no longer contain C14.
Mind you. It will take a long time for all C14 to decompose, and my body will long since have decomposed by then because the half-life is 5 730 years That’s, how long it takes for half of it to fall apart.
If you’re thinking by now cool, but isn’t this about climate change, Exactly After all, the oil and coal that we burn in the industry is nothing more than carbonaceous dead biomass.
I e dead plants dead dinosaurs that have been compressed under the earth for millions of years And in this long time, of course, everything C14 has long since decayed.
This means that the oil and coal are C14 free and the CO2 that results from combustion is also C14 free, And now it comes.
The proportion of C14 in our atmosphere has measurably decreased with industrialization.
This means we can chemically prove that the additional CO2 in the atmosphere comes from the chimneys of our factories, Totally cool isn’t it So not cool bad.
Let’s make it clear that humans are primarily responsible for the current global warming And just to be clear.
The certainty that humans are the dominant factor in climate change is at least 95 97 98 99 Human proportion is almost 100 Of that.
We are very sure, the Alright case is closed.
Let’s continue. What are the consequences? You can see them particularly impressively here.
I’m on Austria,’s largest glacier the Pasterze, Those tiny dots down there are wanderers And that back there is the glacier tongue of the Pasterze.
This ice stream is still several kilometers long and yet only a shadow of itself.
Here you can see the dimensions That were in 1936 when the glacier went almost up here to the parking lot, and even here in 2000, at least back there, this horseshoe was almost completely covered with ice.
I want to take a closer look On the way to the glacier Soon, a 1st challenge, Good that I have Peter with me My mountain guide, So you hold on with your hand That’s the role And over to the opposite slope.
Ok, let’s go Until a few years ago.
The ice here was meter thick all gone.
Just like the torrential meltwater beneath me.
When you finally arrive on the ice, you can only continue with crampons, But it doesn’t help Peter, and I have an appointment with glacier researchers who are at work on the Pasterze today, But first, the dimensions flash me here Around 850.
This glacier had its last peak here. At that point, it was around 250 m higher than it is now 250 m, So much ice was all gone.
We continue sometimes over bare ice, sometimes over scree from the surrounding rock faces that cover part of the glacier, And then finally, we see Andreas Kellerer Pirklbauer and his research team from the University of Graz Every September.
They measure how the glacier is doing.
How far has the ice moved towards the valley, man 94? Above all, how much ice has the glacier lost in the last year? 11.
15.
So I e pretty much exactly 7m.
Have we lost ice here from last year to this year Wow? So you always measure how much the glacier has changed at the same point Exactly Looking further back for 2018, the altitude was 2 218 18 That’s.
Another 7 m, I e.
In just 2 years, we have lost 14 m here, 14 m in just 2 years.
The ice under our feet is still up to 150 m thick. However, how the Pasterze will continue will be decided further up on the glacier where it is colder due to the altitude.
Even in September, there is still snow on the ice here.
Snow protects the ice, but, above all, snow becomes new ice.
That flows down towards the glacier tongue and nourishes the glacier, But even here in the feeding area, the snow cover gets gaps.
Glacier researchers have been observing the consequences for a long time About 40 years ago.
The whole area was completely closed.
That was a big ice break.
Here too, we have found that this does not necessarily increase from year to year, but also decreases.
That is, we have the same tendency to decrease in volume that we have below up here as well.
I would say that this place will be demolished in 20 years at the latest. Then we have a tongue at the bottom, which is just a big body of dead ice that is slowly melting away and will eventually be gone Thoughtfully.
We climb towards the valley, because, apart from very few growing glaciers, most of the ice surfaces are like the Pasterze.
They’re melting worldwide.
Let’s look at the North Pole.
This is what the sea ice looked like in September 1980, when satellite measurements began, And this is how it looks in September 2019, While September is the month when sea ice at the North Pole reaches its annual minimum, it’s a direct comparison of what has Disappeared in just 40 years And above all the multi-year, particularly thick ice, is gone, making the remaining ice surface, all the more sensitive to warming.
But now it gets interesting.
The word Pasterze comes from Slavic and is often translated as pastureland In the former Pasterze glacier bed.
Andreas Kellerer Pirklbauer wants to show us a secret that the receding glacier was only released a few years ago.
Yes, this is exciting.
If you look in there, You see a lot of peat material and organic material. There are so many different layers here Where, if you’re lucky, you can find a small twig.
You can see very nicely that this little branch was compressed.
You have to imagine that the material that lies here grew as a moor, some 1 000 years ago and was deposited, And then there was the advance of the glacier and it compressed it.
It’s really heavy and cold.
Has this washed up here now Or is that from a tree that once grew here Here, you can see that there are layers, In other words, in this case, it wasn’t washed up.
It grew here In these finds one has even found willow branches.
It is an indication that there was once grazing in the area Wait that means 6 000 years ago.
It was warmer up there than it is today And pasture land doesn’t exactly sound hostile to life either and it got colder again afterward.
Does that mean current global warming is much fuss about nothing?
We need to take a closer look Only at this point. It is no longer enough to just look back to the beginning of the weather recording And that’s exactly why I went to Bremen.
I’m doing a kind of time travel today Because to understand the present or the future you have to analyze the past.
Some scientists study climate development over the past hundreds of thousands, yes millions of years.
I’m going to look at how they do it here today, Because here in Bremen lies a real treasure.
So now we’re going into the cold Best you put on a jacket because it’s only 4 degrees in here.
Why does it have to be so cold here? Of course, we also want to properly archive the drill cores In this treasury are a drill, cores Drill, cores that Ursula R hl and international teams around the world have retrieved from the sea floor.
How many samples have you stored here, 158 km in total And that’s 250 000 of those segments that you see behind me here? This is a tremendous treasure, So let’s go in here, And here’s, this particular core segment that I’d like to show you.
When was that lifted? This was drilled in 2003.
I was also part of this trip and that is very valuable.
This drill core is about to tell us much about our planet’s past. To do this, it was cut in half and examined in detail by the paleontologist and her team.
So – and this is now soil from the deep sea – This is seabed from 56 million years ago.
What I notice is an abrupt color change from light beige to brown.
How can you read from this piece of the earth how the temperature on earth has developed? We were able to reconstruct the composition using microfossil shells, And that gives us information about temperatures e g.
It was found there that, with this sudden change in material, the temperature on earth rose by 5 to 8 5 to 8 means the change from a cold to a warm period.
But how exactly does she know that The core or samples of this core were examined for their chemical composition and, very importantly, for the stable oxygen and carbon ratios? She wanted to say oxygen isotopes.
I heard it right Very short and very rough.
Don’t worry, It is about different oxygen atoms, namely O16 and O18.
Unlike C14, nothing is radioactive here, So we’re not determining radioactive decay.
Here we’re determining the ratio of O16 to O18 Because in the water I e in the H2O. These two types of oxygen are present in a certain ratio that depends on the temperature, Since the H2O builds itself into the sediment layers through a chemical reaction, we can read the oxygen ratio from these layers at that time.
So, to put it simply, these layers are chemically encoded photos of the water temperature at that time It’s, chemistry, folks, Chemistry is always toxic and artificial.
When it’s cool.
Nobody talks about it.
Isn’t that physics, instead of chemistry, It’s about the lighter isotopes which evaporate more easily Go on.
Thanks to such methods, we can look much further into the past than just the beginning of weather records in the 19th century.
Let’s go back to the last 400 000 years, Even without industry, there were always warmer periods.
Now let’s look at the CO2 content in the atmosphere Whenever it got warmer.
There was also an increase in CO2 shortly afterward.
Wait a minute after yes after The CO2 increase, follows the temperature increase, But doesn’t the greenhouse effect mean that CO2 leads to warming and not the other way around? Does that mean we are not to blame for global warming? Let’s zoom out for a moment Even further out of The earth.
Doesn’t just revolve around the sun, but sorry we have to go back in exactly, but also around the earth’s axis, which in turn is crooked.
Now there are variations in both the Earth:’s orbit around the Sun, its rotation about the axis, and its tilt.
This creates fluctuations in the amount of solar radiation that hits the earth.
These fluctuations take place over 10 to 100 000 years and are called Mylankowic cycles.
These Mylankowic cycles also lead to fluctuations in temperature and thus to warming from time to time At first.
They are not that big, But Warm water, cold, water, and Warm water are much less able to retain CO2 than cold water, which is why more CO2 is released from warmer oceans.
This means that, even if the warming is not so great, at first more CO2 gets into the atmosphere, This intensifies the greenhouse effect.
As a result, the oceans are also getting warmer again, which means that more CO2 is emitted again, more greenhouse effect, etc, and so on.
We have an avalanche effect and, as a result, we slide from a cold period to a warm period. So in past global warming, CO2 was not a trigger, but an intensifier of global warming.
Today it is both on a planet populated by almost 8 billion people.
So the relevant question is: what consequences do we have to expect for this planet with all its animal and plant species for humanity, for our society today and in the future? To do this, we must first find out how much the earth will warm up if we simply continue to live as we have up to now.
Climate research is trying to model this with the help of supercomputers.
It’s, just not that simple, Because even the best calculator can only calculate with factors that are also known, But can the future be calculated at all? Let’s first see which factors are still uncertain Back on the Hoher Sonnblick.
Here you not only measure the CO2, which we already know very well what it means for the climate but also things like aerosols, tiny particles in the air that trigger the formation of clouds.
Science has not yet fully understood how exactly And that’s, not all You have the sun, you can see it beautifully today climb down bring energy into the atmosphere.
The earth also radiates again.
If you have a cloud there, for example, the cloud absorbs energy from both sides.
The question is: what does she do with it? Does she beam them back Or can she emit them back into space, Or does it keep them trapped in the atmosphere so to speak, and contribute to warming? That means they can have a cooling or warming effect. It’s an incredibly complex process.
That’s not fully understood, which is why our research up here is groundbreaking for the climate change effect.
Accordingly, climate models have also developed tremendously in recent decades.
In the beginning, in the 70s, the models were still quite simple: The climate was modeled using solar radiation, precipitation, and CO2 concentration, But little by little more and more factors came into play.
E g clouds, the influence of land surfaces or sea ice, But climate is even more complex.
Gradually it became clear what else had to be taken into account: Volcanic activity, sulfates from industrial fumes, The influence of the sea rivers, aerosols in the air Water flows within the seas, interactions with vegetation chemical reactions in the atmosphere.
As you can see, it is a complicated calculation with many factors, at least some of which are still unknown at the moment.
The climate data center in Hamburg, one of the digital brains of international climate research, Here high performance, computers, processes, vast amounts of climate data, 130 petabytes, And the result is climate models.
Forecasts about the future of the earth’s climate.
But how do you want to calculate something precisely if the relevant factors are not yet properly understood? I want to know that from Detlef Stammer, director of the Center for Earth System Research at the University of Hamburg, There is more and more data. At the same time, there are more and more uncertainties, Isn’t that a contradiction That doesn’t contradict itself, because you have to understand what is uncertainty For me, the greatest uncertainty is a lack of understanding.
If you understand the system better, but still can’t get a very sharp number at the end, a range Isn’t it necessarily a greater uncertainty, but a better understanding of what we can predict and what we have to live with.
Science means because you answer one question: 3 new questions open up.
It is the epitome of science that the more we understand about the world, the more complicated it becomes With this globe.
Detlef Stammer shows why climate scientists are so convinced of the models.
Despite all the uncertainties, The first thing we see here is a simulation of the present.
They compare the calculated data with reality Here with satellite data from the North Pole.
I e you make comparisons with the past.
Look.
Was our model correct? This can be compared with the real values. Then the assumption is obvious that the prognosis for the future That’s exactly how it is.
We can see that well here in this other picture in front And what this graph show is.
On the one hand, the one in yellow, which is observing global temperature, is observed as it is up to now In gray, are climate simulations that follow.
This observed temperature quite well, And that also creates confidence in the predictions.
The climate models can achieve a great deal, But there are difficulties in regionality.
There are also other situations where the role of the ocean is sometimes underestimated.
The big global story – you can do that pretty well, But the smaller the area gets.
So if it’s about East Westphalia, then it gets really difficult.
The way the clouds are simulated in the climate models, in addition to the aerosols, is the biggest uncertainty globally and also regionally.
As far as the uncertainties and possibilities of modeling are concerned, the experts are largely in agreement. Climate models are not predictions of the future, But modeling can calculate different scenarios from best case to worst case and estimate probabilities.
While this isn’t the crystal ball with which to look into the future, it does give an important picture of what we need to brace ourselves, for The climate models show possible future scenarios.
This is what it could have looked like if we or industrialization had not existed In no case will we achieve that in the very best case, maybe even that If we reduced emissions to 0, we would be in the green here That’s the best case Worst case, then, correspondingly different.
If we continue as before, then we expect an increase of up to 4.
You have to let that melt in your mouth By the end of the century 4 or more.
If we continue as before 4, global warming would have massive consequences for life on this planet.
Not only would heat waves become much more common, but The risk of drought would also increase in some regions and the risk of flooding on rivers and coasts.
In many regions, resources would become scarce, famine, the shifting of vegetation zones, and the wiping out of entire ecosystems.
All of this is threatening within a few decades And mind you 4 global warming on average would mean that some land areas warm up much more than 4.
Let’s hold on Just going on as before is a very bad idea, even if it doesn’t seem so dramatic for Germany at first I’m in Cuxhaven. I want to know how sea level rise will affect the German coasts.
The first thing I notice on the dyke are the marks of the many storm surges and that the highest of them was almost 50 years ago.
I meet J, rgen Schubel, the dike master of Cuxhaven.
He knows his way around here.
Are people worried here So the sea level rise, which you hear a lot about in the media, is, of course, a concern for many, Because actually, all climatic changes are a threat to people?
I sometimes get calls from Mr. Schubel, should I sell my house in Cuxhaven? Can the dikes withstand climate change at all? He wants to show me something at the edge of the water.
We had a very average high tide this morning and you can see that the water that went over this edge is still standing here, And that happens more often a week which used to be different, And the sand that has formed everywhere here has also been swept By the water onto the promenade here, So there are changes here too today, but is that a cause for concern When I was little 60 years ago? I walked here and as a child, I was afraid of the high water level, which was also in the same place as there, but on average 30 cm lower And that’s.
What my father told me at the kitchen table 60 years ago, And that was the first foreign word I had to learn in my life, namely the secular rise in sea level.
What does secular mean The centenarian, And that is related to 100 years or 10 years because it is not quite even from year to year.
Surprisingly, in recent years here in Cuxhaven, the level of the average high water has been a little less than 30 cm in the hundred-year average, namely only 27 5 cm. So sea level rise.
Isn’t a problem On the east coast of North America.
Near New York, for example, or in Bangladesh, or on some islands in the Pacific Sea level rise will have a completely different meaning and a completely different effect than the effects of changed storm surges.
For us, Germany can cope well with a sea level rise of 1 m by the end of the century, But only because our coasts were particularly well protected after the devastating storm surges of 1963 and 1976.
But this makes the North Sea region an exception.
Worldwide Climate research can say that there is a very high probability that Bangladesh or the islands in the South Pacific would be threatened by sea level rise and that floods would become more frequent, as is the case here.
However, just as the temperature will not rise equally everywhere.
E g urban vs rural sea level will not rise equally everywhere either, Which makes it difficult to make concrete predictions globally or to seriously simulate them, And yet, even here such extreme storm surges as in 1976, with 1 5 warmings would increase.
Statistically they no longer occur.
Every 500, but rather every 100 years, With 2 warming every 30 to 40 years. It is undisputed that it makes a clear difference whether it is 1 warming, 1, 5, or 3.
What does sea level rise depend on? First of all, water expands more with warmer temperatures so that the sea level rises as a result.
Of course, there’s all that melted ice.
Not this.
When ice melts on water, it doesn’t affect sea levels.
It’s as if this ice would melt here in the glass, then it won’t overflow either, But when land ice melts e g in Greenland or the Antarctic, water is naturally added.
The sea level is rising.
Detlef Stammer shows me this using Greenland.
As an example, What would happen if the mainland ice melted completely there? How likely is that, For example, a tipping point for Greenland would be a temperature at which so much ice melts that Greenland can no longer build up an ice mass again?
This tipping point: the exact value is not known at the moment. It’s between 2 or 3 degrees, where the system starts losing more mass than it can ever build back up, And then at some point there is no more ice.
That means when such a tipping point is reached at some point, Greenland will more or less lose the ice sheet, And then up to 20 feet, more sea level rise will happen because of this mass that can get into the ocean.
The tipping point theory says that from a certain level of global warming certain climate processes can no longer be stopped, such as the ice sheets just seen.
Yes tipping points Popular topic with us journalists That sounds not only dramatic but also very clear, But within the scientific community, it’s anything but clear.
There is little evidence that the climate system has a major tipping point, But there are various regional local elements that could represent a tipping point.
The Amazon rainforest the arctic sea ice, maybe monsoons.
However, I am a bit reluctant to make these statements.
The crucial tipping point is the role of the polar oceans.
We assume that we have about 12 15, very important tipping elements.
The likelihood of things like this happening is relatively small, And the research here is still very much in its infancy. That means the whole thing is highly speculative.
The tipping points are a good example of how scientists communicate differently, Some focus on the worst-case scenarios, while others emphasize the most likely scenarios.
Both perspectives are based on science, Except that the worst-case scenarios make the better headlines.
I can understand both points of view.
I can understand why people would want to concentrate on the worst case.
Scenarios based on the motto rather than expecting the worst.
If it doesn’t get that bad, you can be happy, But I can also understand when you say that this does not represent the entire scientific situation And that leads to escalations.
There is usually far too little time in the media to communicate science in a differentiated manner and with all the uncertainties.
In my opinion, this is one of the main problems, Because, within science, uncertainties are dealt with fairly aggressively Example.
The Intergovernmental Panel on Climate Change, IPCC for short, which collects classifies and weights the state of the art, even has a separate chapter for it in its last status report, Key Uncertainties, Central uncertainties, The tipping points, the question of how the climate is changing, regionally E g, Where it is getting drier, where wetter, how high the sea levels are rising, All of this is one of the central uncertainties according to the IPCC Good. But who is this IPCC, actually IPCC or Intergovernmental Panel on Climate Change, is not on his door sign, But Jochem Marotzke is one of the hundreds of scientists working on the Intergovernmental Panel on Climate Change reports, The head of the Max Planck Institute was even one of the Coordinating lead authors of the last IPCC report.
He is currently working on the next strictly scientific, But in the end, politics comes into play.
I am very happy to finally meet someone who is working intensively on the IPCC reports.
How does the IPCC work, Perhaps the most important thing to say the IPCC does not do its research? What IPCC does is compile and evaluate the knowledge we have about climate and climate change, But to what extent can one speak of independence when the 195 governments involved in this summary for political decision-makers were involved? In the report? The moment we’ve agreed on this summary for decision makers.
It means the scientific community and governments agree.
This is the core of the scientific knowledge on climate change.
All governments have agreed and they can’t get out of it.
In this respect, this co-production of knowledge by science and governments is also the strength of IPCC.
It was this process that made these historical images possible in the first place, The Paris Climate Agreement 2015, The message from Paris.
Despite all the uncertainties in detail, the facts are so clear and so serious that over 190 countries have committed themselves to limit warming to 1 5. If at all possible, It makes a noticeable difference whether it is 2 or 1 5 warmings, Because what would happen at 2 With these 2 warmings, things like the destruction of ecosystems are also triggered, which in turn bring more CO2 into the atmosphere, But also the shifting Of the climate zones, just the tropical rain belt, with a huge impact on 3 billion people, This will mean changes in precipitation patterns.
That will mean changes in extreme weather events, In particular heat waves, heavy rainfall, Possibly changes in storms, melting of the Arctic sea, and rising sea levels.
Changes then affect biodiversity.
Food production, The changes are extreme.
I’ll say it as plainly as possible.
If we don’t do anything about global warming, our world will be different And a less good one at that.
But do you know what the good thing about man-made climate change is That we humans can also do things differently And for that scientific discovery alone, we should be thankful That’s, why I’m trying to combine the optimistic and pessimistic voices and say Thank God, we still have it in our hands, But how can this work Mai, and I asked ourselves that in Part 2 of our climate documentary, We take you with us in our search for the best solutions to the climate problem?
Full the UFO Doesn’t smell good Copyright, WDR 2021.
