 The next talk, we are saying hi to Leonhard, Boca who is going to talk to us about his research project, I think about the astronomy and the climate crisis. Have fun with Leo, but Leo is muted. I've just been told that people aren't hearing me. Yes, they can hear me now. Great. So let's hope that things will now work. So I want to talk today about astronomy and the climate crisis as announced. That's not really my research project. It's kind of my sideline research. So I would like to say first what I'm going to talk about. First of all, there is going to be an introduction, and I'm going to introduce myself and the topic. I will tell you how I got to get into this topic. And then there are a few items about the actual topic. So are there actually astronomical influence factors on the Earth's global climate that has been claimed? What is there with these claims? Then I'll give you a short introduction what the climate crisis actually is. But you will know this, but just as a reminder. And then the item, the main issue will be that there is no planet B as you frequently hear in rallies. That is actually an astronomical statement. What does that mean and what can astronomy contribute to solving the climate crisis? So for the last one or two years, I have been fairly active in this. Firstly, in reducing our own greenhouse emissions as astronomers, first to understand them and then to reduce them. And then to see what we can actually communicate, how we can communicate the message that there is no planet B, no Earth-like planet in a good way, hopefully leading to finally get some good, make people care well for this planet. So what does an astronomer actually do? People, when I tell them that I'm an astronomer, think that I go out at night and into the field with binoculars or a telescope and watch the stars. Yes, that is what astronomers did. But these days, we don't really work this way or quite rarely. In my career for about 10 years, I was out observing for seven or eight times, mostly in Chile, where you see me here next to the very large telescope as it's called, where you can spend a few nights observing and you can be lucky if you get one night or two there for once every one or two years. And then, of course, a lot of observing is done remotely. This is what that looks like for the computer friends among us. You can see that there are many computers involved. And of course, there is a large network and a lot of technology. And if you observe things such as this galaxy, one of the closest galaxy, about 13 million light years away. And that's what that looks like on a screen, highly complex panels with all kinds of information. So you see the state of a program that was running on the left, a very old programming language, tickle decay from the 80s. If any of you remember, it's not easy. It's very complex to program, but that's how much of the software works. And that shows me the state of an instrument and the results that you get are then processed live. So you can get an immediate impression whether it is what you're looking for. That is one part of my work. That's the research. But the largest part of my work is actually to get together a project for this new project, which will be the largest on earth called the extremely large telescope. As you see, as you remember, the Chile one is called very large telescope. The next one was to be called overwhelmingly large telescope. But now that is going to be the name extremely large telescope. And this instrument called Matis with which you can look at earth like planets, in particular around a star system called Alpha Centauri, which is a triple star system, the closest one to us. And you know this from the trilogy, a history of the earth, if you've read it. And there is another very nice Chinese science fiction. So Alpha Centauri A is the closest star and this probably has planets. And if they are in any way like the earth, so they have the similar albedo kind of a reflection index. That's what it would look like. There is a fairly conspicuous dot here and a fainter dot. And you could then see whether any of these is like the earth. And we'll talk about what we can do with that later. But first of all, we're going to talk about astronomical influences on the earth climate and what astronomy can contribute to solving the issues. So first of all, astronomical influences and some of you that have looked into astronomy may know that the sun is not equally active over time. It has cycles. There was a 22 cycle and this cycle of 22 years within this cycle, the magnetic field of the sun reverses. And because that is a process with two ends, you say you're half the time and you have an 11 year cycle in which the activity of the sun changes. You will see that this with these solar spots that you can observe using very dark glasses. You have to use very, very dark glasses. Otherwise your eyes will be permanently damaged. But it is possible to see these solar spots with the naked eye, but not right now if you have these glasses. So you have to wait another five years until they will be of return. So what does that have to do with the earth's climate? There were some researchers or pseudo researchers in the 70s and 80s that created a lot of noise about this. So we have a global temperature curve here that is slowly rising and below that the solar activity, the density of solar radiation, which led these people to say climate crisis, climate change is all about the sunlight changing. But if you look a bit further, you see that that was only a random correlation for a limited amount of time between 1920 and 1960 more or less. And after that, these curves diverged quite a lot. The temperature kept rising, as we know, more than one degree above the pre-industrial level. But solar activity goes up and down and doesn't really contribute to that. So this question can be quite clearly declined. Sun's activity is not responsible for the change in the earth's climate. And then there are the ice ages, of course, and there is a complex graph here that you may want to look at. But it's very insightful. First, let's look at the left. The x-axis shows you the age or the time in the past in kilo years. So the left hand slide is the present and the right hand part is 600,000 years ago. And the other graph is the concentration of an oxygen isotope, 18. Heavier than normal isotope, normal is 16. You find the 18 isotope in ice cores because the heavier oxygen tends to fall down. It has more mass. So it will accumulate in ice cores. And if you see this isotope rising, then that gives you information that more water was in the ice phase. And if you look at this so-called proxy across time, then you see that there are peaks about every 100,000 years. And that is, in fact, the information that you take to say that every roughly 100,000 years, there were ice ages. And the last one, as we know, ended about 20,000 years ago. And you can see that here at the right hand side. But if you look further back, you see that there is a regularity to that. And if you do a Fourier analysis and ask which frequencies are dominant here, you see that a cycle of 0.01 per kilo year, so 100 per kilo year, which means once per 100,000 years frequency, that is a repetitive pattern here. And people were wondering what that actually is. And we're looking at various astronomical factors. For example, the Earth's orbit eccentricity. So the non-roundedness, the non-circularity of the Earth's orbit, the Earth's orbit is an ellipsis, and the ellipsis changes somewhat. It kind of oscillates, not too very much. Then there is the actual tilt of the Earth's axis, the angle to the orbital plane. And that changes between these two values here, between about 22 and 24 and a half degrees. Then there is the perihelion procession, which is quite interesting for relativity theory, for relativity, because that showed us for the first time that there is something like relativity in the planet's movement in the solar system. And these movements could not be predicted completely by Newtonian mechanics. And then there is the orbital inclination, the frame of reference being here. Here is the plane in which the planets move. And that mainly is Jupiter as the heaviest planet. And the orbit is the orbit of one particular planet with respect to that. And the Earth's orbit is not exactly in this plane, but it is slightly inclined, a certain angle. And that changes. And again, you can look at those changes and plot them, the inclination over time. And you see that that is changing. You can run models on that. And the cycle is, this frequency is similar to the one that we found for the ice ages. Once everyone had 100,000 years. And that is the signal that tells us that the change of the orbital inclination, every 100,000 years, could actually be a major contributing factor for the ice ages. And an astronomer called Milankovic shortly after the First World War realized this. And the theory that we have is that within the ecliptic itself, there was a lot of dust from comets, asteroids and whatever from the time the solar system was created. And when Earth goes through this plane or spends its orbit in that plane, then there is a lot of dirt, roughly speaking. And that leads to a cooling and to volcanic eruptions and an ice age. That is the theory behind it. It's all theory for now. But it is a cycle that has an astronomical correlation, but it's a very long cycle, very slow one. If you compare this to the CO2 concentration that we see now, it's very clear that over these 100,000 years, the CO2 concentration changes. But what is happening right now at the zero point, it's an extreme peak. We're just coming out of the last ice age at this point. And suddenly we are at a level, at a normal level, about 280 parts per million in the air. That is the share of CO2 particles in the air. But that share has dramatically risen in the last, in recent days. It's about 300 and looks like 280 in the graph. But it's much stronger than it was in the last 100,000 years. And there was a nice graph by a physicist who is very good in making these statements succinct and to the point that's the XKCD comic. And you can see us starting 200,000 years in the past with the temperature then 22,000 years. So the temperature was about four degrees below what we have now. And by now we are by at one degree above. And if we don't do anything, we will be at two degrees above. So that is quite a difference. So a bit earlier 10,000 years before the present, we reached the temperature that we had. And it stayed quite constant over time. And now in the last few years, the rise is so extreme, so fast that that really is a climate crisis. So to summarize, the contributions to global warming, as I've said, solar contribution can be seen. But overall, the net contribution is not really there. And then there are other variables there. Volcanoes can have a contributing contribution there. They can lead to cooling. But the human contribution is by far the largest. So there's no way of saying that there are other reasons for that. But not everything is bleak and gray. This is from a website called the Climate Action Tracker, partly built by the Potsdam Institute for Climate Research, one of the leading research institutes on the climate. And they list what the national contributions that were agreed upon in the Paris Agreement to what extent they would help to reach, to limit warming to 1.5 degrees, which is what we want. And we see that at the moment, things seem to be working perfectly as we think we are about at about 2.1 degrees warming, which is not that bad. But it could be much worse. So to me, this means in particular that there is hope, but you really have to finally get active. Don't just exit from coal electricity production in 2038. But earlier, it can be done, but you really have to do it. So what can the astronomy do? So real problem. We cannot really do much about the big issues. But what can we contribute? And one thing we can do is reduce our own carbon emissions, because it's not that small. And the second thing is to report about what astronomy can report about these issues. So my colleagues in Heidelberg from the Max Planck Institute have calculated how many CO2 emissions they're producing. And you can see that half of all the emissions are due to flights taken by members of the institute. So electricity is another 30 of that. So electricity production can be made green, flights are much more complicated. You cannot simply go to the US or Australia by any other means. So per person, that's about nine tons for one year. And you can break that down per article published. And or as a German citizen, you can calculate how much emission you have per person. For example, 11 tons for a German citizen or 1.6 tons for an Indian. Other colleagues at the European Southern Observatory, they have calculated that most of their emissions come from electricity produced. And that is mainly due to the fact that the electricity is produced by burning fossil fuels. And the reason Chile has been picked in the first place is that in those places, there's almost always sunshine, very low humidity. But that means that during the day, the entire installation has to be cool. So it's cool enough at night to make the observations. And the third study I was involved myself in. And we looked specifically at flights for a conference. In 2019, we had a conference in Lyon. And we looked at who's producing most of the emissions. And we can see that most of the emissions come from a very small set of participants. And we can see how many people have made how many trips. And it wasn't that many trips, but a lot of emissions. Because a flight from Sydney to Lyon takes a lot more than, for example, from Amsterdam to Lyon. And of course, if you can move to trains, that makes it a lot better as well. So a solution needs to be found for long-haul flights. And so that has been reduced involuntarily through the pandemic. So the conference last year took place, but completely online. And so we had a comparison of what the emissions were. We can quickly look at that for the computer fans. So we asked around how intensely they took part of these about five and a half hours. And how much emissions the laptops produced by using electricity. And we took the average CO2 emissions per kilowatt hour. In Germany, that's a lot more. In France, it's a lot less. The network uses a lot of electricity. So the amount of CO2 needed for transferring one gigabyte is going down every year. So that's getting much more efficient. And we use Zoom as the video service. And the subject was that we were using a single server for that. So that wasn't a lot. So in total, for 1800 people, took together only as much CO2 as a single return flight from Liverpool to Lyon. So it's a factor of 3,000 less in CO2 usage for that conference. A very good example. It worked really well. We had discussion forums like here at Divock. And people enjoyed it a lot. And so it's easy to work together without having to travel that far. Finally, the second point. What can astronomy help do about climate change? And what perspective can it contribute? And communicate about things. And as an example, I took this wonderful picture that was taken by the crew of Apollo 8. They did not land on the moon. They just circled the moon before returning to Earth. And after going around the moon for the first time, they saw how beautifully the Earth was rising across the moon. So they were completely fascinated by the Earth rising. Very blue, a lot of water, and just black around it. This view towards Earth, very special. So our planet is kind of a spaceship itself. Much more intense impression for this view we get from this later image called pale blue dot. Depending on the video quality you might see this very small dot, 0.2 pixels, that is Earth as seen from Voyager 1 beyond the orbit of Neptune. And this probe was turned around to look back, not looking forward, but looking back to Earth and take a picture not just from Earth, but of the entire planetary system. And this was very risky because turning the probe around meant that the antenna would point away from Earth for taking this picture. And so they had to write a program that would turn the probe, take the picture, then turn it back around to have the antenna point back to Earth. And that of course worked. It's still working. It's still delivering data and it has delivered data from beyond what is considered the border of the solar system. And this image is really a wow moment for many, many people. This one little pixel makes it very clear that this is the only place in the universe we have. And if we look towards exoplanets, we already over 4,000 planets have been discovered outside of our solar system. And none of those discovered so far do we know that it's like Earth. We know not of a single one that has liquid water on it. So we don't know that yet. And even if we knew it existed, we couldn't travel there. We could build a spaceship that could travel there over hundreds or thousands of years, but it's not a plan to save Earth. And that also applies to plans of very self-convinced entrepreneurs like Elon Musk. So what else can astronomy do for us? So when it's dark, we can see lots of stars. And of course, that is extremely fascinating. We can see the Milky Way is taken from Chile and the laser is pointing at the black hole in the center of the galaxy. And it's the understanding that the incredible distances, thousands of light years, they're so immense that if we were looked back to Earth from there, it would be impossible to spot. So there is no other option. We cannot go anywhere else. So if we take a further look, a wider look, we see a huge number of galaxies like our own. And in our galaxy, we have about 200 billion stars. And we have about 200 billion galaxies in the universe that we can observe. But in the area we can observe with the limits of light speed and everything. So on average, we have 200 billion galaxies, which each have 200 billion stars. So hopefully we can get in touch with other civilizations. But that's not anytime soon. And we shouldn't get distracted from the problems we have here today on Earth. Okay, that's it. I started a bit late, but here I have 10 minutes left. I had planned for half an hour. So we figured we give you a bit of time to not stress you out. And we can tell the viewers that the question pad is open. And you can find it in the Faplan in the schedule. If you look at the details of the talk, there is a link in the description to this question pad. So let me give you a quick summary then. And having a nice discussion might be nicer than just talking at the black screen. So the most important thing is really about my talk. There are astronomical influences on our climate, the changes in the inclination relative to the ecliptic. So probably it is the source of the about 100,000 year cycle for the ice ages. But it has nothing to do with the situation we find ourselves in right now. And also changes in the sun are not affecting our climate like we're seeing right now. All of that is really caused by our own behavior. What's really important is we are seeing this unbelievably fast change in the CO2 levels in the atmosphere. The humanity will not end, but our civilization might be. So if there's not enough drinking water, it gets too hot, the sea level rises, that will change the way we can live a lot. So what can astronomers do about that? But we can be critical of our own behavior, our own CO2 usage, and there is a lot of places that are far away from Europe or the northern hemisphere in general. So in those places, green energy use is not very advanced and moving away from fossil energy sources is a big thing. And the big thing, of course, for us is to allow people to better understand the fascination and take a look from the cosmic perspective as the small marvel that the Earth is a very special place. We know of no other place like it in the universe and we really have to work on this together to work on this problem. Because it's the only one we have. Okay, so that's about the end of the about 30 minutes and I'm very happy to start the discussion and over to the herald. Thank you very much. That was an unbelievably interesting talk and seeing all these great examples that you've put together and we are getting some questions and also notes and here's a little reminder. There is a self-organized session after this where you can continue the discussion. So while people are still writing questions into the pad, when you started working in astronomy, did you ever envision that you would talk about the climate? No, definitely not. Absolutely the opposite. One of the big things for me really was to be able to travel. That was one of the reasons I thought astronomy might be a nice field to work in. So during education you get a lot of opportunities to travel to all kinds of places in a very international environment and since living in the Netherlands for the past four years with my family and okay, am I going to buy a house here? So being able to travel was a big thing and yeah, we did buy the house. It's really a problem that it's a problem that will increase significantly in the next couple of decades and I only realized that in the past couple years and I talked about it with my colleagues, mostly women who are very active to work against the climate change. Somebody writes in the pad, you are producing a lot of enviable optimism. I had the same thought during your talk. Are you seeing chances that starting from the science community with the conferences, etc, can we manage to make that change? Thank you for that comment as well. I think from the scientific perspective we can show a lot. We can be an example and can show how international cooperation can work without having to travel all the time. So everybody has seen that during the past year and astronomy is a particularly international field. We work together with pretty much people from all over the world, Brazil, Chile, the US, Europe and being able to do that online and having the tools to do that, that helps a lot. Two weeks ago, I was part of a conference that happened in a virtual reality system. I got an Oculus Rift and had to use Facebook for that but it was very interesting and lots of things were possible and I think it will become more and more normal to do these kinds of things. Towards optimism, I want to say I hope I'm not blindly optimistic and I often see it in very dark colors and how the rainforests are torn down and how slowly the exit from coal power plants is happening in Germany and I see all that and I'm very angry and sad about it and that politicians are not thinking far enough but despite all these developments a lot has happened in the past six years since the Paris Agreement. Not enough yet but the Climate Action Tracker is showing that very well and it's going in the right direction and I'm hoping that this is not a linear development where things are getting better linearly step by step but that what I think that the problems are going to be more visible and that we can increase the speed of change for example by the increase in solar panels installed and I'm really hoping that we get to the point hopefully in the next few years. Okay, now we have to do it. It's economically viable and do the change for real and that we can increase taxes on for example coal power plants so they become uneconomical and can be shut down. That sounds like a very sensible vision of the future and I hope we can work on that all together. So we have no more questions in the pad or are waiting for the session to talk to you directly and somebody is writing into the pad. One more thing, we'll wait quickly for that. So if you had a wish free what would it be? One more wish. So I got a similar question. So who would you like to talk to if you could choose freely and I said I want to talk to Chancellor Angela Merkel. She's a physicist. She knows all this but she's not doing enough despite clearly knowing all this and I would really wish she would in the last month of her tenure she would make some real decisions and shut down the coal power plants by 2025 for example. Excellent, fantastic wish. If I had the possibility I would try to do that immediately. The one question that was added it's slightly off topic but also very fitting. So as a chosen Dutch person are you riding bikes a lot? So my family and I have ridden bikes a lot in the past and of course we are riding more bikes. For three years ago we actually sold our car and here in the Netherlands you don't really need a car. You can use a buckfeet, a bike with a basket in front. So I don't think we're using bikes a lot or more than others but just the normal amount that is very usual here in the Netherlands and it's absolutely normal here. Not everybody does it. There are people who drive their kids to school in a car but at the same time we ride bikes a lot more. Yeah maybe if I had a second wish free what value real bike lanes have so that is a very good thing. Yeah it would help. Yeah people who don't like to ride bikes in cities because like me had an almost bad accident. So one question I'll take with us with a short answer. How do you feel about civil disobedience as a form of political protest? Paint your own bicycle lanes? Why not? Yeah they have to be safe. So maybe it's probably something like extinction rebellion which who I have worked with in the past. So to a certain extent we need a certain amount of civil disobedience to wake people up. Extinction rebellion has done demonstrations and actions at the airport in Amsterdam's couple the largest airport in Europe and they did a die-in and that created a lot of a lot of media attention especially if the police are overreacting to that so that's helpful and of course you have to make sure that the activists themselves are safe but I think it's really important to get media attention it has to be represented in the media much more. Okay let's take that as the final word Leo thank you I hope we see more of you soon