Kipppunkte im Klimasystem: Vortrag von Prof. Dr. Stefan Rahmstorf auf den Naturschutztagen 2022

Professor Ramsdorf, yes, it is a great honor for us to have you here with us today as one of Germany's most renowned climate researchers. I think most of us know him from radio and television, but I would like to briefly introduce him. He was born in Karlsruhe, in the southwest. Therefore, he is not unaware of it. He studied physics in Konstanz, by Lake Constance, and also in Ulm, and then found his field of research in oceanography, that is, the study of the world's oceans. He got his doctorate. He was born in New Zealand in 1990 and has worked at the Potsdam Institute for Climate Impact Research since 1996.

He belongs to one of the most cited presentations in the field and is considered one of the most important oceanographers in the world. , for example, in the status report of the Intergovernmental Panel on Climate Change (PC) and, of course, you are also a highly sought-after advisor in politics and the media and also for me and What especially impresses me, I must That is to say, they do not limit themselves to just doing science in the ivory tower, but they also actively go out to the public with the alarming results of their research, write books and articles and give lectures like I personally give here today, I can still remember My first book I read on the topic of climate change.

It was this little blue brochure published by Beck-Verlag and it was from you. That's how I started and the complex topic of climate change. Many complex connections only became evident. I then, as a student, reading this book became aware of them. They also repeatedly explain fake news and false claims by so-called climate change skeptics and for their educational work in 2017 they also received the communication award from the American Society for Geosciences I thank Professor Ramsdorf for being here today and I look forward to his lecture . The stage is yours. Thank you very much for the kind presentation.

It's a shame we can't see each other live in Radolfzell. , so to speak, right in my hometown, because I lived for many years in Allensbach and I am always happy when I can be on the beautiful Lake Constance, but of course it is also nice to do it online and I share my screen with the presentation here. I hope you can see it now and yes, I assume you will. I can also listen to myself and that's why I start right away with the matter. I would like to explain what the tipping points are in the It's about the climate system because you always read about them in the media or hear about them and a lot of people don't even know it.

It's not exactly what is supposed to be a tipping point in the climate system and this title slide that maybe seems a little drastic. , but this graph is very frustrating, actually in a nice way what it's all about. You can imagine a simple example of a turning point like this If a ball is placed in a hole like the globe here and if this person pushes it a little bit to the side, then it will roll back into the hole and that's what We call it a stable equilibrium, but you can already see when this person closes the ball.

Far from your balance point, that is, above these moments, try to differentiate more, that is sometimes a bit complicated with the first slide. Now I think I have understood it, yes exactly, so when the ball is pushed beyond this maximum point that is marked with the arrow, it no longer returns to its original state but to a completely new state here on the right edge of the image and that is actually the essence of a turning point and there are many such turning points in physics and in everyday life. All you need is a simple nonlinearity as we physicists call it. and an example would be a kayak, for example, if you travel with a kayak on Lake Constance, this kayak normally remains stable horizontally in the water and if you lean a little to one side, the kayak recoils back because it is integrated. in the same way that it has a stable balance horizontally, but if you lean too much to one side, the kayak gives way and you swim in the water, which is an everyday example of a tipping point and this non-linearity and tipping points are examined . in physics in all sorts of contexts, and as you might expect, there are a whole host of subsystems in our climate system that behave like the ice sheets or the Atlantic circulation, which I'll talk about in a moment, that we're experiencing right now. moment.

The fact that the Earth is warming enormously can also be put in the context of the last 20,000 years of climate history, that is, since the peak of the last ice age, which took place between 18 and 22,000 years ago today, and you can see the warming. There in the Holocene, between 18,000 and about 10,000 years ago today, almost 7 degrees and then the very stable climate of the Holocene in which humans settled, agriculture was invented and it is actually the history of the civilization of our species and We have already had a degree of The warming of the last 100 years is behind us, that is, about ten times faster than the natural warming due to the cycles of the Earth's orbit at the end of the last ice age.

Here you can also see several future scenarios on the right side: 24 6 degrees of warming depending on our emissions. In any case, we are catapulting ourselves out of the Holocene. From the experience of the history of human civilization, we have already done so. According to the climate data we have today, it is already warmer. than ever in the entire Holocene and then you have to go back to the last warm period 120,000 years ago to have equally high temperatures to find the way in which we have already achieved it today and the question is whether we will now intervene so massively in the Earth system.

To avoid this, possible turning points can be overcome and two years ago we published an update on this issue in Nature. Of course, we have already participated in a whole series of publications in the specialized literature on points and in this Nature article. Once again we have given an overview of what tipping points we are approaching and what you can also see in the graph on the left: the connected parts are drawn like this. Because the current research is largely about how these tipping points interact with each other and, in certain circumstances, can support each other, just like dominoes can topple each other and yes, here's an overview of what that we want to address today: sea ice in the Arctic, Greenlandic founders protect Atlantic circulation with snow I would also like to address coral reefs so that we can also analyze a biological system and an ecosystem, because the concept of overturning, of course, also It is known in ecosystems, not just from physics and, first of all, a bit of discussion about what exactly it is.

Now, a turning point. I have already given a simple example with the ball in the hole. By the way, the points are becoming more and more important. In the last report, which was published last year, the sixth report already mentioned the points in 97 places in the report and in the previous fifth report there were only 27, so you can also see how this tilt problem is discussed increasingly among experts in the reports of the Intergovernmental Panel on Climate Change and therefore The basic article on tipping points was published in 2007. I was also one of the co-authors. The first author is Tim Lenton from Great Britain and it was also the result of a German-British workshop on turning points that took place at the British embassy. in Berlin and which finally gave rise to this specialized publication a few years later, and there the points are defined as points at which a part of the climate system, which we call tilting elements, with a relatively small change in a control parameter, which It could be, for example, simply the global temperature or an amount of CO2 in the atmosphere, this subsystem then undergoes a relatively rapid change like this style system with this red line, what is at this critical point?

If you now imagine that time would go from left to right because from left to right the control parameter increases, for example the global temperature, then in a relatively narrow range a drastic change of the system occurs and we can distinguish between two types of turning points. In the image on the left, what has already been shown would be a system that has only one equilibrium state for each value on the x-axis, that is, for each value of the control parameter. This red line can be clearly assigned when it is at a certain value in the equilibrium states to the same value of the control parameter has as this blue area of ​​the call all the bistability here this system would practically have two stable states and if it is in the upper branch of the stable branch or in the lower stable 2 is the lower solid The line then depends on the prehistory.

A classic example of this would be the Greenland ice if it has two stable states in the current climate. One is the one we know, the Greenland. There is ice on the vertical axis of this diagram and that would be if we are now here on this upper branch and we increase the temperature, which means we are now going to the right, it will shrink a little bit, but the kayak leans a little. to the side when I lean out, but there is this branch point or inflection point of the online language, if we go up to that, then this system practically falls to the lower branch because the upper branch no longer exists and that founder has two stable states. in that sense, the current climate is that this lower 24 continuum is also stable, that would be a continental ice-free prairie and if we simply removed the ice from Greenland today, then with a gigantic excavator we could sweep all the ice out to sea, it wouldn't come back to appear in the current climate.

This state of Greenland without ice sheet is also stable even without further warming, which was already stable in the pre-industrial climate because then the surface of Greenland would no longer be three kilometers high due to the thick ice sheet where it is very cold in high in the atmosphere, like in the high mountains, and then it would simply be too hot in Greenland without this ice sheet to re-form a new ice sheet and that means the fact that we have a founding die is because we come from the last ice age where an ice sheet formed and it is also stable in the current climate in the pre-industrial climate, but once it disappeared it would not return, whereas if we go beyond This point of Zion on the right then the ice of Greenland would be irretrievably lost and if we then cooled the climate again and went back to the left if, for example, we could restore the pre-industrial climate by absorbing massive amounts of CO2. from the atmosphere, then the founders would still not return, it would simply disappear.

That is what is meant here by multiple equilibrium states, which is really irreversible. Even if the climate can be turned back, the ice will not return here. and between these two stable branches there is usually a stable balance that would be a quality group. If you start from a ball in a valley of this type, this landscape would then have two valleys. The ball can remain stable and in the middle there is a ridge. where it could balance exactly on the ridge, but if you pushed it slightly in one direction or another it would probably roll in one direction or the other.

That was now some theoretical sea ice in the left case that would come again if we cool the climate again which also returns every winter: sea ice, the Atlantic circulation and the Greenland ice are examples of this second type of tipping point to the right and that also applies to the west, a practical signal during the transition now if we think about what will happen in the next 100 200 years we will warm the climate the transition that would be practically the green line looks like this so for this transition to a warmer world is not like that at all.

It is relevant whether we have in front of us 1 turning point of the first type or the second type. Here we see again a general map of different tipping points and their interaction from a new publication and, by the way, it also comes from a publication for the Climate Summit in Glasgow. It was prepared by several scientific organizations and was presented there. Not all of these key points can be covered here in the next half hour, but you have already seen it again with an overview. "Take a closer look at some examples. Example one is sea ice.

So the sea ice cover in the Arctic Ocean was still in the 70s. From the right we see founders with continental ice. I think the Most people know this, but there is, of course, a very fundamental difference between sea ice and continental ice. Sea ice is simply frozen water. The surface as you know it on a lake, which I know is simply made up of frost. and this ice sheet in the arctic ocean that is only two or three meters thicker than continental, unlike the snowfall that forms when this snow just never melts. but it just melts.

It continues to accumulate so that it creates a mountain of snow so big that it begins to flow towards the edges of this continent, since it is 3000 meters thick and not three meters deep.thick and is made up of fresh water that just ended up there. due to snowfall. So the fundamental differences are both turning points. I'll look at it now, let's focus on the sea ice and that has already decreased massively, that's what it looked like a few years ago when the previous low was 2012, but it's been very similarly, in the last few years almost half of the Sea ice cover in summer has already been lost in the Arctic Ocean, which means that it has also become thinner and the thickness of the ice has also been reduced by about half, so that in summer only about a quarter of the mass of series 1 is still present in the Arctic Ocean compared to what it was before.

It's only been a few decades and we'll probably hear from almost everyone here today, but we'll still experience this situation where the Arctic Ocean will be virtually ice-free this summer for the first time if we don't massively stop warming now. Sea ice cover is increasing over time in the Arctic Ocean, so since before direct measurements began this light blue curve comes from so-called proxy data that can be reconstructed from sediments in the Arctic Ocean where you can see if there was an ice sheet there or not the blue dotted line the dark line showing the observation data from In the 19th century there is the and then At the end the trend of the satellite data is shown here on this line dashed red, so you can see how drastically the ice sheet has fallen here and my colleague Marcus Rex from Potsdam is the leader of this historic expedition to the North Pole with the Polarstern.

It was said that later we saw how the ice died hotter. Now I want to get to the hot prairie, so the continental ice here you can see a photo of the huge green ice sheet and the meltwater you can see formed there on the surface, what happened. It is precisely with the summer thaw that these meltwater lakes are formed here. The summer thaw has also extended significantly. In recent years there have been times in the summer when almost the entire Greenland ice sheet melts on the surface and the problem is here in a model. The simulation showed that this ice sheet then slowly recedes and also moves away from the edges, that there is such a simulation made with a continent as a model and that this can also cause a sharp rise in sea level if the Greenland ice sheet has enough ice. cover global sea level by seven meters and increase if it melts completely.

We know that Greenland ice cream has a tipping point through ice cave feedback. That's exactly what I tried to explain before, that it has 12 equilibrium states because there is a self-reinforcing feedback effect here, which is that when I melt the ice, the surface automatically turns into warmer layers of air. . As I said, a layer of ice 3000 meters thick at 3000 meters above sea level is, of course, "Very cold. Everyone in the mountains knows this. When the ice melts, the surface automatically becomes warmer and warmer layers of air. At some point you will reach the point where complete melting will be inevitable and self-perpetuating because essentially there is this feedback loop: the lower the height of the ice, the warmer it becomes.

The question is, of course, where is this tipping point? You can't do that that easily Unless we finally do the experiment with the real ice sheet, we can't do that, but we have computer simulations that are also calibrated with the last warm phase I already mentioned, the warm period before the last ice age, when the Greenland ice sheet has largely melted, and we did this several years ago. in the photo in my apartment, such calculations of simulation where we run many variants, thousands of variants of our ice sheet model over the last 200 thousand years until the penultimate ice age, through the EEM warm period, then until the last ice age and then until the Holocene. to see how much the Greenland ice sheet develops under these climatic conditions and in which we vary all the uncertain parameters in such a model to look at all the options because of course there are always uncertainties in such models and they will be systematically analyzed and then compared the degree of melting in the warm period is reproduced correctly from these 1000 model variants and so it will be with a proportion of these variants, others have too much or too little melting and then we just select.

They also correctly reflect the extent of the Greenland ice during the EEM warm period and we then used this subset of models to calculate the future and it turns out that the tipping point at which the grasslands will completely melt is between 1 degree and 3 degrees of warming global. Yes, there is. We have already left more than one degree of warming behind us - around 1.2 degrees compared to pre-industrial levels - and that means we could already be past this tipping point, maybe that's also the case because it wouldn't be so easy determine whether it has occurred or not.

Nothing drastically different would happen shortly after the tipping point than shortly before, but the difference would be that further development over the next few hundred years would lead to a complete, self-perpetuating and reinforcing melting of the Greenland ice cream and before. from the tipping point Not at all, but what will happen there in the next ten to 30 years does not differ at all and therefore it cannot be said from observational data whether the tipping point has perhaps already been passed or not , but if it is overcome, this would also happen without further global warming. Sooner or later, this would cause a seven-meter rise in sea level, because the Greenland ice would simply be completely lost, which would be an unimaginable catastrophe for all coastal areas of the planet.

I think right now we have 130 million cities right on the coasts of our planet and even if the sea level rose just one meter, many of them would have really huge problems and just to show that this stability behavior with the two equilibrium states also comes In our climate model, in our green model, this stability diagram is already an old publication from 2005, back then Hermann did not make such sophisticated graphs, but on the x-axis here there is practically radiation, so ultimately It's a kind of warm-up. , a measure of warming. On the right it gets warmer in this diagram and the volume of the founders shield 30 is shown upwards and you can see these two equilibrium states in a central area dark blue with Greenland ice and light blue without founders there.

This is with a lot of modeling simulation with the founder's readings? The model has been verified in detail and the Greenland ice is already losing mass. I don't think it's necessary to mention that here in this circle this is NASA measurement data that simply shows with satellite data where the founder has lost mass for a long time, that everywhere is blue, where it is red, the ice is growing, which is not like that anywhere, but even at the top above, the greener you are already losing mass between Let's go to Antarctica because that's where headlines have been appearing in recent weeks like these apocalyptic glaciers, basically the glacier of the end of the world, the Trades glacier threatens to disappear because its ice shelf floats in the water, as you can see here in the photo, it is now in the sea Floating ice shelves that threaten to break up due to more wool from this glacier and why is it so dramatic?

We have already seen several such ice shelves, especially on the Antarctic Peninsula, which in a matter of months broke relatively quickly into practically a thousand pieces and moved away and, for example, the outer ice shelf was a great example of how this It will happen due to global warming. Before that, the science was already in Certainly, in the 1970s in the main specialized magazines and, unfortunately, in the last decades, as predicted, what was seen, for example, in a Larsen B 111, was that when the ice quickly collapsed it almost came loose. into the sea, it crumbles and disappears, then the continent behind it starts to flow faster and that's when this ice shelf acts like a stopper or a cork in a wine bottle essentially stopping the continental ice from escaping because in In many places the ice shelf sits on a rocky surface.

There are footholds where the ice is fixed as if firmly in place and if it breaks, the continental ice begins to flow and this Waits Glacier, which joins here as part of the The Outlet Glacier of the Ice Sheet West Antarctica would then begin to drain rapidly and in accordance with both the theoretical understanding of stability here in West Antarctica and model simulations also used here in the photo but also by other groups. If the West Antarctic Ice Sheet had been removed, the entire West Antarctic Ice Sheet would flow inexorably into the sea. That alone would cause a global rise in sea level of three and a half meters, which is very uncertain in this case.

What happened was completely drained because that can take centuries, but it can also take thousands of years. That again depends on details in the modeling that cannot be captured with complete certainty. Basic physics is now understood, so if that happens to you, then we will do it. stabilize West Antarctica and it will be lost, how quickly can it happen then these dynamic flow movements can occur? You can't simulate that reliably. A consequence of both the melting of Greenland and West Antarctica is rising sea levels, and the rise in sea levels has accelerated. Here we simply look at the measurement data shown here and I think of course you can see the acceleration here with the naked eye, now it's little because some people wrongly criticize the satellite data added to the level. data, but even if the level data behind the satellites is allowed to continue running and displayed to this day, the satellite data would practically cover almost exactly what the satellites do.

Measurements show that sea level rise corresponds exactly to what the level data shows. "So the level data taken alone already shows this acceleration here and it's not surprising that sea level rise is accelerating because the hotter it gets, the faster the ice melts. That's simple. Of course, you can easily test this if you take it out of a freezer and let it melt at different temperatures and the faster the ice melts the faster the sea level just rises and the Intergovernmental Panel on Climate Change actually has new scenarios for future levels of the mar in their latest report here, the development has been demonstrated. and they are really new because the PC has not done this in the previous reports, but what is new are these top scenarios with dashes and dots and there you can see risk scenarios which say that sea level rise may also be significantly higher than before.

The PC said this because normally, if you look at the very thick lines here, the area, depending on the missions, we would have to wait between half a meter and 1 meter of additional sea level rise around the year 2100, after that, of course, it will continue to rise. the graphics card a little beyond 2900, but if we look at these risk scenarios, the psi says that we cannot rule out more than two meters for 2100 and even more than five meters for 2150 cannot be ruled out due to the new findings on the Climate models cannot be recorded reliably either and have always been very conservative: the US national climate report identified risk scenarios of two meters or more 2100 years ago, because they are also included in the specialized literature and what is new is that the conservative Intergovernmental Panel on Climate Change pc is too cautious in its consensus procedure which now practically if I say admits but that is exactly what I wanted to say that there is a very one-sided risk here in Fortunately, this is now very, very unlikely in the next thousand years, but what it means in concrete terms is that we can no longer afford to lose one or two percent of this ice mass and we are at the end.

During the last ice age, during this transition to the Holocene, with a global temperature rise of about 67 degrees, we lost two-thirds of the Ice Age ice. masses with a sea level rise of 120 meters, so now it can be believed that we could warm the Earth by 23 degrees and almost all continental ice will remain. For us, that would be very naive and what such an increase means. Did you just lose the image now? That may be fine, it's coming back now, there's an error message here right now, what it means for a littleisland state, for example, like here, the main island of the Maldives, you have to Just look at this photo to know that even a sea level rise of one meter would be fatal and right now you are thinking about a storm surge.

It is evident that it is difficult to defend an island like this. The Maldives is already building a new island that will be two meters higher, where a small part of it will be. Then it is assumed that the population will be relocated, so of course large parts of the coast or even cities with a million inhabitants cannot be protected, but that may be possible. with such a small island in a very flat sea area. Now I would like to move on to the other tipping point, that is, the Gulf Stream system and that is one of my main concerns since the early 90s, when I started as a postdoctoral researcher. at the Kiel Institute of Oceanography and that the Gulf Stream system is part of a global environmental circulation where the water is coldest and therefore has the highest water density.

When it is reached, it flows into the depths, so it sinks into the depths and that is into these deep-water organic educational areas and then it spreads into the depths and the warm surface water flows into the North Atlantic, where these used to be. deep educational areas and if you just look at the temperatures for the previous five years on the NASA chart. "Here you can see that the entire planet was unusually warm. Logically we have global warming, a strong increase in the Arctic. That is all known, but there is an area here that was colder during this period and in the last 100 years it has It was even cooled that this famous gold remained in the North Atlantic exactly in the region of deep water formation where warm surface water flows, emits its heat into the air and then sinks into the depths and we can This can also be seen in the simulation in a climate model, which is now shown here in an animation.

This is what the Gulf Stream looks like. The surface temperature is now. No one here sees the Gulf Stream as a band of warm flow in a simulation of the model in which American colleagues from Princeton lose. at a global level Ocean climate models with very high resolution have a very realistic representation of ocean circulation and together with my PhD student FGC Satz we evaluated the simulation results of this model for a CO2 global warming scenario and if we look at how the sea surface temperature develops one after another CO2 increase and then you see a region of cooling and less warming south of Greenland.

Their model shows it relative to the global average sea surface temperature, which is warming, meaning that what is blue doesn't necessarily have to cool, but also warm less than the global average and everything. which is red warms more than the global average and there is not only this cult blog south of Greenland in the model, but also a strange and strong warming. the American coast and in a model you already know what the theory is. Behind this it is also understood that both phenomena are reproduced in several other models: this cold area south of Greenland and the strong warming on the American coast are a consequence of a weakening of the Gulf Stream system in the model if you now look at the observed temperature trends in sea surface temperature over the last 100 years, you can see a very similar pattern in the North Atlantic to this fingerprint pattern. of the weakening of the Gulf Stream and we also believe that this is exactly what is behind it, which is evidence that this gold current system is actually weakening and a series of sediment data shows this as well.

Here is a study we published last year based on the work of many colleagues who evaluated sediment data in their studies, allowing conclusions to be drawn about the circulation of the Atlantic and as you can see here over the last 1500 years, the curves are all decreasing in the last 100 years, indicating a weakening of the Gulf Stream system that is unique in the last thousand years. In summary, it can be said that the founder meltwater also contributes to weakening the Atlantic circulation, so we have an interaction between different tipping points. And this circulation has a tipping point due to a salt transport feedback that arises so, I have not yet explained that when this flow weakens, less salt is transported from the subtropics towards the north, leading to water being even less saline and therefore becomes lighter and can therefore sink a lot.

This further weakens the circulation and this can also be understood in simulation calculations with beautiful and real three-dimensional ocean models. This is a stability diagram very similar to the one for Greenland ice cream, which I explained before. I want that here now Explain it again because I think I have to get to the end slowly to stick to a time and that's why I skip the Greenland thing a little, sorry about the Atlantic circulation because I would also like to say a few words about the corals. Here we see an image showing coral bleaching on the Great Barrier Reef in Australia in the years 2016, 2017 and 2020 alone and we see that around 85 percent of the Great Barrier Reef was affected by coral bleaching. , so we are in the middle of a Great Barrier Reef mass extinction, which of course is really tragic for all nature lovers.

In 2016, here you can see how a coral no longer has color after bleaching and after a few months it is covered with algae and then it dies and if you compare where these same ones were in these three years Coral bleaching and that puts the anomalies on top of the sea temperature, it is always where the sea temperatures are particularly warm, when is the The reef is bleached, so it is not any environmental pollutant reaching the sea, or is it a very clear temperature effect because corals also have a turning point. They can only have a certain limit of temperature tolerance and, above that limit, they simply compensate and this can be observed around the world and not just in Australia's Great Barrier Reef: of the 100 examined, only the points blues escaped coral bleaching in 2015 and 2016.

The Intergovernmental Panel on Climate Change says that with two degrees of global warming, virtually the entire draw will be lost "If we can limit warming to 1.5 degrees, we can save between 10 and 30 percent of the coral reefs. I have to get to the end now so you can get rid of your questions. There are not only bad social bonding points, but also hope for positive social change, like the fall of the wall, for For example, where things suddenly start moving where practically nothing seemed to have changed for decades and I hope that we are close to that tipping point of social change towards finally taking climate protection seriously and taking the climate crisis seriously.

I would like to end with this hopeful perspective so that we still have time to discuss this. I would like to thank you very much for your interest in climate change. Luckily, already The camera shown has been updated again and again and is now still available for purchase in the current completely new version. Many thanks to Professor Ramsdorf. Unfortunately, the applause cannot be heard in this digital format, but of course there are also questions and all that. There will also be time to ask you questions. Take advantage of the opportunity that is available to us. What did you take away from the chat with the cost question?

You just gave the right keyword. Of course, we can't really recreate it vehemently, but at least we can simulate it. We have the function of raising our hands. Who, if sitting in the milk market, would simply give frantic applause? Please raise your hand. , we have seen that the pointer goes up I have to plug in the plugs as soon as possible, ok 80 90 percent, great old man, thank you very much for this loud applause, Mr. Ramsdorf. Now we are getting into the question. There are some questions that were actually already addressed by a certain Ramsdorf in his lecture.

I thought it was an interesting question, Ramsdorf, how do you manage to stay optimistic despite this depressing news, because you find yourself in a situation? which many conservationists know in the same way that we just fight at windmills and we have a lot to do with depressing news, how do you manage to stay optimistic, so I think the important thing is to stay optimistic and deal with these types of situations is be active. When you get involved yourself it is easier than when you feel helpless and stuck and are sitting at home, so I would recommend everyone to become active in Transfair Future or other groups, nabu bnd etc. to join because then you will know to many similar people. positive-minded people and you meet many committed and excellent people who help you stay there.

It's a long way to go until we finally achieve the shift towards climate protection, that's clear, but you can stay optimistic by being together with other active people, well, so there were several questions about this green topic the EU taxonomy how Do you evaluate this current development that gas power plants should be classified as sustainable? Yes, I think it's a contradiction in terms. They say it is a bridging technology, temporarily. We may still need gas power plants as long as we have not fully developed renewable energy. A temporary solution, by definition, is not really a sustainable solution and that is why I think it is the wrong signal, very wrong.

Well, I wrote which one. If the founder and the ice sheet had completely disappeared, they would have had an impact. Of course, they said there would be a sea level rise of about seven meters, but that could also have other effects and coupling effects. I could tell you something about it. , yes, so there is Yes, this interaction between the tipping points that I have already briefly mentioned, if the Greenland ice cream melts faster, then of course large amounts of meltwater will reach the North Atlantic, dilute the water there and consequently will further weaken the Atlantic circulation, perhaps beyond the point that it is exactly that.

At the end of the last ice age, it also happened when large amounts melted and the Atlantic circulation collapsed, which in turn significantly changed the temperature difference between the northern hemisphere and the southern hemisphere. , so the Northern Hemisphere is warmer than the Southern Hemisphere overall because the Atlantic circulation is also huge. Amounts of heat are transported across the equator from the South Atlantic to the Northern Hemisphere and this in turn displaces the tropical precipitation belts, which are where it is found. warmer in the tropics. Today that is a little north of the equator because the northern hemisphere is warmer than the southern hemisphere and so on.

You can also see this in the Palio proxy climate data that if the Atlantic circulation breaks down then the tropical precipitation belts diverge southward and that endangers parts of the Amazon rainforest etc. So all these things are connected in the climate system and I can only urgently warn against causing one part of the system to overturn because that will bring with it a whole cascade of bad consequences. This relates to the next question asked: whether we would be prepared for this if, for example, the Atlantic circulation changed. Maybe there will be a new stable flow, even at the new stable level. , which you could then prepare for, you may have already answered a bit.

Yes, that's an interesting question that I haven't answered yet, but what is certain is that there is a global ocean circulation. no deep water formation without such deep water sinking, for really fundamental theoretical reasons, essentially because the ocean on a surface warms, so deep water formation must always take place somewhere and such environmental movement can only stop temporarily during a warming phase, but somewhere there is still colder water, which then sinks again and triggers a new revolution. If it has to happen again in the North Atlantic, that is a completely different question. It could also be so.

So there could be a stable circulation where deep water only forms on the day of the continental range, but that is now more of a philosophical question for the future and because this balance exists, we are talking thousands of years in the future when it comes to of what kind of The new equilibrium levels out again because all these changes in the deep sea take a long time to occur. I think we have named some divers among the guests. The topic of corals also seems to be of interest to some people. that there is a possibility that corals will be found in colder areas of Merkel and then re-emerge, yes,I think yes, it probably won't go completely extinct now, but that will take a long, long time, thousands more years.

Of course the sea level issue is also important, coral bleaching with sea level rise to a certain extent, but if sea level rises too quickly that will be too difficult and with massive sea level rise of the sea at the end of the last ice age, coral reefs also drowned. There was a sea level rise of 120 meters and then in the Holocene. were able to reestablish themselves at the then stable sea level. You just said: be careful with risk somehow. Approaching a tipping point is now again the question of the Amazon in the rainforest area, Weidmann can estimate in this area. which is already far from the turning point.

We know these tipping points exist, but we can't say exactly where they are. In fact, I gave a quantitative estimate for Greenland that it is between 1 and 3 degrees. This turning point is, of course, a wide range of uncertainty Typical of this type of non-linear phenomena that depend sensitively on the exact circumstances and, of course, can only be approximately approximated to reality in climate models or in a model of Amazon forest, which is what we have at the Potsdam Institute, but not in every last detail. If the question of where the tipping point is depends on the exact details, then we simply have to say that we have a very wide uncertainty about the Amazon, but it is safe to say that further deforestation is actually more dangerous than warming at the moment. , so that's the idea.

Stabilization of the Amazon forest is being driven through greater deforestation because the smaller the remaining area becomes, the more unstable the Amazon becomes in the face of further warming because it is also a large ecosystem that stabilizes and also generates or recycles precipitation. , etc., and more and more This forest is shrinking and is also becoming more sensitive to global warming and is in danger of drying out due to droughts or even going up in flames. Now I have another question that is asked more frequently. when the Gulf Stream deteriorates. What does this mean for us in Europe?

When it comes to adapting to climate change, we are now preparing even more in cities for the fact that there will be many hot days. Does this mean a new ice age in Europe or can't that be said at all and a second question that would also interest me personally: What about the permafrost soils, which are basically affected by the fence? How is this currently evaluated? Yes, I will I share my screen again very briefly when I'm there because I have a slide of a study about what's happening to us. Temperature. What exactly happens, of course, depends largely on when this Atlantic circulation really comes to its knees, on how much global warming.

We have already had and it is a simulation shown by colleagues from the US and China that was published in 2017 and where the Atlantic circulation is relative. Yes, I don't want to explain in detail how you did this calculation, but it can happen. that in winter the temperatures of this blue zone even fall below pre-industrial levels in the areas of northwestern Europe, Great Britain, Scandinavia and in one place Iceland are affected, which happens exactly in this region, but there are other consequences which also affect us in Europe There is a critical study that shows that we would expect stronger winter storms and there are other consequences: The ocean absorbs less CO2 because CO2 is produced precisely in this deep water formation with the sinking of surface water to great depths.

Several thousand meters deep in the ocean, CO2 is also transported to the deep sea, where it is initially in safe hands and away from the atmosphere and not more directly influenced by the permafrost soils that form when frosts release methane. when they defrost. "It's also a tipping point and that would increase global warming. Methane in the atmosphere is also increasing and it's also a very potent greenhouse gas and the question is this budget bill, where does this increase in methane actually come from?" in the atmosphere? It's a very active field of research, I say, and it hasn't been clarified ultimately, it probably comes mainly from pipeline leaks and traces etc., and not from the faster permafrost or gas hydrates in Of course, with further warming the permafrost will melt and methane will be released and gas hydrates in the Arctic will stabilize from the seabed and more methane will also escape.

We can probably increase warming by a few tenths until 2100. That is less dramatic than it sometimes seems in the media. At least the general assessment is, but the long-term consequences are already dramatic because it cannot be avoided. May the permafrost continue to melt for many centuries. And we're creating a source of greenhouse gas for the atmosphere that we somehow can't plug, so it's really a mortgage for many centuries, even if it probably won't cause any dramatic additional global warming in the next 50 years, and if I do it, then. can because that fits a question that was presented here, ccs, to capture carbon, store it, take carbon or co2 out of the atmosphere, so to speak, using technical processes and then press it somewhere underground and near the other question, technology was shared.

Optimism is partly spreading that we will then find solutions, that is, inventing better ones, banning the city, as was also said in the election campaign, or what do you think, what scenario we really need for our economy and our life. system here also in Europe but, of course, throughout the world, if we want to prevent the things that you are investigating, so to speak, well, I think that in a crisis situation like this you cannot simply expect something to be invented that save us here because Also, we have very little time. If to meet the Paris goals we have to halve emissions worldwide by 2030, that is, eight years from now, we cannot wait for great inventions to emerge.

Of course, it's good to invent new things. and there is now a pilot fork capture system in Iceland, which extracts CO2 from the free atmosphere but which only for pension purposes costs around 1,000 euros per ton, so it would be better to introduce a CO2 price of 100 or 200 euros per ton . ton now and avoiding emissions is definitely much cheaper in the foreseeable future, not to mention the question: the quantities that can now be extracted with such a system are, of course, a drop in the ocean or not even that , because right now we are imitating 40 billion tons of CO2 a year, an unimaginably huge amount every year to get it all out again.

That's not actually foreseeable, but I think at best you can expect that if we have largely zero emissions in 2050 and some remaining emissions can be reduced to zero now, where it is especially difficult in the field of agriculture or something like that, then we will have a small remainder. It can be compensated with systems like the one now put into operation in Iceland. "Can you give our active members of the Leonardo group some advice on where it is worthwhile for volunteers to work on this topic. What can you specifically do? The feeling we have for everyone Well, that's not an old question.

Of course, I'm I'm a basic researcher and I don't necessarily have a deeper insight than you. Maybe you have an idea about it. Maybe you can say a word about it. I think the most important thing to solve the problem of this climate crisis is not really what everyone What he does at home is, of course, nice. I don't have a car and I don't have photovoltaics on my roof. That's all good, but the important thing is that political decisions are made, so I would say that there is political commitment to a government. that really takes climate protection so seriously That a fair contribution to the Paris goals can be achieved, that is actually the most important thing.

It also raises this question that just came. Climate researchers are repeatedly accused that their information is accompanied by great uncertainty, which then makes it easier for politicians to get out of the matter. How can we respond to this criticism? First, it is a hallmark of serious research that I learned as a first-semester physics student that Economists always listen to growth forecasts with high levels of certainty. Well, I'm not sure if that's the fault of an economist or media reports, because the media doesn't always indicate the range of uncertainty, even when reporting on our uncertainty. results, but I'm just saying that other scientific areas have uncertainties at least as large.

The thing is that they are often not discussed in the same way as in climate research, where politicians are actually looking for an excuse to do nothing or delay things. , but the answer is that uncertainty is not our friend, uncertainty means risk and that is exactly what I have with the sea level example. People, the uncertainty is also totally one-sided towards much worse sea level rise than we've always heard about. Intergovernmental Panel on Climate Change. There is no uncertainty in the direction that perhaps it could be significantly less, everything has been happening for a long time, okay, well, something else has been noticed.

In the questions that have come in, I think we actually already have many of them. There was a question right at the beginning that I think would now be more of a scientific question, where I think we shouldn't ignore it if the Greenland ice is melting now from the greenhouse effect. Gases are also stored in it so to speak, which are then released, there are also pockets of gas, stories like that, is it relevant or irrelevant? I don't think it's important because the amount of air that is trapped in these air bubbles are of course infinitesimal compared to the entire atmosphere and if there are air bubbles there then they largely have the CO2 content of the Ice Age, which was lower than before, that would be around 180 ppm and then that would be welcome. dilution of CO2 concentration but I said a negligible amount is fine but it is good that this question can be asked because I have never heard it before and from time to time new questions keep coming up despite many lectures that I have never been asked . a question, then wait and see what else comes up.

Also in Germany there are important areas that need to be protected, where there is ketchup that could trigger a tipping point in continental Europe or now I am without electricity and the Atlantic is of particular importance, yes. Well, like I said, our permafrost areas have certain kipoi where they appear, there are those in Europe too, but I know. Now I'm not sure what that could mean, so I can't think of a better answer. I go over a lot of questions, I don't think there is anything significantly new or I hope we don't have much to praise or forget because there is a lot.

Unfortunately, most of the questions only came up when he finished his presentation, so Let's talk, kids. Maybe one more point. One of the first questions will be given in this presentation later on the home page and had announced that we would be sending the Gene P against the Audi spd. You did very well, then we will put it back in the Nature Conservation Days review and Mr. Ramsdorf also agrees for us to record this lecture, which means that it will soon be available to all viewers as a broadcast after this lecture again on the Nature Conservation Days page, I think it's wonderful looking at the clock we have the next lecture on time at 3:45 p.m. you should take a break after a good hour and a half of video footage, so my suggestion now would be that we warmly talk again with raps about thoughts on this conference.

Those who submitted questions I ask you to understand that we were not actually able to transmit questions again. I think we have now received a very good addition to the conference and I would now like to allow everyone to take a short break and then verbally in 1545. Please continue Mr. Ramsauer, thank you very much, I am fine and I hope to return soon live and in color to the Radolfzeller . Yes, thank you very much for the introduction, a comment, but I can't also say something from the chat, greetings from Allensbach Allensbacher wrote thank you very much for being there and with great pleasure