 I'm Katrin Meisner, I'm an ARC Future Fellow, I'm an Associate Professor at the Climate Change Research Centre at the University of New South Wales. My research is about climate feedbacks. And I work with earth system climate models. So these are models that have pretty much all the big components of the climate system, ocean, atmosphere, vegetation, sediments, ice, biogeochemical cycles. And I'm interested in feedbacks in the climate system and thresholds. So basically if we tweak the system a little bit, how is it going direct? It's not always linear, it's a little bit like if you have a glass of water at the edge of the table, you can push it a little, you can push it a little at one point it will fall down. So I'm trying to understand if we have these feedback thresholds in the climate system. My research is about past, present and future. And in the past I have focused mostly on abrupt change and I'm especially interested actually in abrupt warming events. So we know in the history from our reconstructions that climate has changed quite dramatically and has warmed up quite dramatically in the past. And that was even without any humans being around or at least not actively interacting with the system. So I'm trying to understand what happened during these episodes and if this is likely to happen in the future again on top of what we are doing right now to the climate system. So I would say most of my research was actually about the last ice age, the deglassiation, then present and future. But I have several studies that go further back, so when dinosaurs were around or even further back. The last deglassiation happened over the last, started about 20,000 years ago, that's when it was really cold. We had lots of big ice sheets in North America, mainly the Northern Hemisphere actually. And then it warmed up and this ice warmed, but it didn't do this very smoothly. It went back in force and we had big warming and cooling episodes in there. And I think people, I'm not sure on the exact dates, but it was probably done in 10,000 years ago. So the deglassiation happened between 20 and 10,000 years ago roughly. I think for me the key lessons are that CO2 in the atmosphere didn't, it did increase over this time, but it didn't increase linearly. And there were periods of time where CO2 really increased quite rapidly and then stopped again and increased rapidly again. And I don't think we really understand where this carbon came from. So this is one of our main research areas right now in my field and there's lots of people working on it. And how the whole system was interconnected. Like why did this carbon come out at that point? Did it come from the land or from the ocean? Probably from the ocean. Why? Where? These are still open questions. And I think for me a nice or maybe a little bit scary result is that our models can't capture the sensitivity of the system. Our models don't seem to be responsive enough. They seem to be too stable. And that of course if that's true is a problem for our future projections. If we can't get the past variability in the past, warming events right, how are we going to get the future right? Are we not underestimating some of the effects that are going to happen? The past tells us that the climate certainly does not react linearly to any changes from outside. So for the deglaciation when all these glaciers started to melt, we know that was probably triggered by solar insulation during the summer in the Northern Hemisphere which started the whole melting process. But then there were lots of other feedback that kicked in and forced this first trigger. And we know that these feedbacks were not linear. So one of the major misconceptions right now is that people argue that the climate has changed in the past and therefore what we see now might just be part of natural variability. This is not true. And the changes we see now are so fast and so enormous that doesn't compare to anything we actually have in the records. Certainly not in the last two million years but also if you go very far back, there was maybe one event 55 million years ago which was associated to a big increase in CO2 but even that happened at a much slower rate than the rate we are changing the climate right now. So looking into the past can tell us a little bit about how the system might react if we push it but the way we push it right now is out of context of anything we can see in our records doing the quaternary. So basically if you look at the plots, I mean if you just look at the temperature reconstructions of CO2 plots, you see all the variability. You have ice stone here and integrations here and it goes like this and today we are up here. So we are completely out of this range of variability. No model is perfect so you really need to define the problem you want to look at first and then you can decide which model would be useful. It's a little bit like you're going to the doctor and they think you might have a tumor. There's different ways of analyzing and visualizing what's happening in your body and the doctor will tell you, oh we need this kind of scan or this kind of. It's a little bit what we do with the model. So it's a whole zoo of models. They are related but they have different strengths and weaknesses. So all these models share lots of characteristics and of course the physics of the models are very, very similar because they're all based on the fundamental same equations of fluid dynamics. It's the same equation that we knew that equation since hundreds of years. They are based on the same thermodynamic equations. So what differs in the model is the resolution. Basically a model is like if you would construct your world out of little legal blocks and it's basically the size of the legal blocks. So you can buy a really expensive legal Star Wars ship. My son has those. They are very big. Expensive takes a poor parent two days to build them and they have lots of detail. Or you can buy a little car for a three-year-old which doesn't have that much detail but it's made out of big, big blocks. And in a way that's one of the differences between these models. Another difference is how much biogeochemistry they have in there. That's a whole new component. And how much different components they have in there. Some have really sophisticated ICE models others might not have ICE models. Some have sediment models others might not have that. But the fundamental equations for fluid dynamics are the same. I started off as an engineer. And during my studies I realized that I knew that before I liked the ocean. So I did a general engineering degree in France but with the option ocean. And I really wanted to work in Africa. The only way to do that easily was to work for an oil company which I did. I earned a lot of money for a few months and I hated it. So I went back to school and actually did a masters in physical oceanography and a PhD also in physics and physical oceanography. Because I realized I wanted to work for the ocean but not exploit the ocean. So that's how I started. I guess I got into it because I love the ocean. So I really went in through the oceanography. But by starting as an engineer and then doing a PhD in physics. So I have had people commenting on the fact that I might be biased in my opinion about climate change because of course I would like to have climate change problems in the headlines because that's where my salary is coming from. My response to this is that honestly I think we know enough about climate change. The physics are solved. I would be much happier not to have any money into climate research but put the money into impact research and into renewable energy research. The physics of climate change are settled. We know what's happening. We don't know all the details, small details, regional forecast. I mean there's always things you can research but the science is actually settled. So I would be very glad to actually shift a little bit our attention here and go into what are we going to do about it. The whole communication of climate science I think is a very difficult question but I'm not a social scientist or a psychologist but from what I understand is it always used to puzzle me that why wouldn't people believe climate scientists although they do believe that doctors like if they are very sick they wouldn't go to see their plumber or their gardener and take their advice they would actually go to see a doctor. So why is it that climate scientists for some people don't seem to have a respected opinion and from what I've read and I think that's human psychology if you have made up your mind you make up your mind not always based on specialists. You make up your mind of what your friends say or what somebody says who you're respecting a lot and once you've made up your mind it's really hard to get you out of there even with arguments. So I don't quite know how to better communicate. I think what's really important is to communicate to children, communicate to schools, communicate in easy words. We are not very good at this. In simple language, maybe not simple but in not a specialized language and never get frustrated although it is very frustrating. Look, yes, I have sometimes with taxi drivers so somebody I sit beside in a plane and when I realize sometimes you can feel it just from the conversation you have with them and then when these guys ask me what my job is I usually just say I work at the university, I'm secretary. I just don't go into it and probably that's wrong, probably I should but I have had these discussions with random people and they usually don't accomplish anything. And these people are people I'm actually interacting socially with like other parents from school or my dentist or then I actually go into an argument and tell them what I think and what my opinion is based on which fact it is based on but random people in the street know. In a short way I can say look there's a fundamental relationship between CO2 and temperature and you can see this from different ways. You can just do the fundamental physics of thermodynamics and radiator physics at CO2 will absorb long wave radiation and re-radiate it. If you don't like this approach you can look at CO2 records from ice cores and temperature records and you see how nicely they correlate. If you still don't like this approach you can also just look at present day data actually and see how this is satellite data so we can trust this and how well they actually correlate. So I think we can go there from different directions and the conclusion is always the same is CO2 and temperature are really tightly correlated and we have put lots of CO2 in the atmosphere so the story is very easy. We should stop putting CO2 in the atmosphere and we should probably try even to find a way to get the CO2 out of the atmosphere again. So you're recording right now? Oh. We won't. That we may put in somewhere. That'll go in the trailer.