 So, the next session is, it's a climate primer. And so, Chris field will be giving us a primer on what is the climate science everyone should understand and how those economics inform climate projections. I'm going to do a very, I think everyone has all of their, everyone's bio. So just a quick introduction of Chris who is the Perry L McCarthy director of the Stanford would institute for environmental. He's also a Melvin and John Lane professor for in the disciplinary environmental studies. He has worked extensively on climate change, especially looking at solutions to improve lives now, decreasing the amount of future warming and supporting economic vibrant economies. He was a co-chair of working group two of the Intergovernmental Panel China, the IPCC between 2008 and 2015. So he's been involved in the climate modeling community for a while. And so, Chris, I think I'm going to leave it with that and you can further introduce yourself if you think I missed something. And I think we have, let me confirm you have about eight minutes and then we'll do questions again. Thanks very much, Pauline. And if you guys want to bring my slides up that'd be terrific. I also just want to say how much I've enjoyed and learn from the presentations so far. I think the similarities and differences in the worldview between the climate science community and economics community are incredibly important that they overlap extensively, especially in the broad area of risk. The message that I want to start with and really finish with is that the current state of climate science provides a platform for macroeconomic analysis that's robust, but also really, really limited. And it's important to recognize the robustness in terms of our ability to understand and project long term trends in global temperature. It's important to recognize the limits to our ability to understand and predict extremes, regional patterns to make detailed forecasts on spatial and temporal scales that are that are longer than a than a few weeks with the kind of detail that makes a difference for, for example, emergency responses. I have a way to characterize the current state of climate science understanding. Next slide, please. Do I have control. Okay, thank you. Is this summary statement from the IPCC six assessment it's unequivocal that human influences warm the atmosphere ocean and land widespread and rapid changes in the atmosphere ocean, cryosphere and biosphere have occurred. The impacts of those have been extensively documented and want to call out the really important work from soul shang and Tim Linton and in terms of adding a really thick and important layer of empirical confirmation. Next slide. I really want to speak to two issues advanced please and one more. To emphasize the kind of sweep of time and the way it's influenced our, our understanding of where we're headed in terms of climate and want to swing back and close with a couple of comments that that they'll already really opened up, and it's the important appreciation that carbon dioxide is a cumulative pollutant and that changes in climate are cumulative emissions since the beginning of the industrial revolution. And even when we bring net emissions down to zero were still left with the total amount of warming that we had at the peak. Next slide please. And, and to start. I'll go to this opening figure from paper that was published in science a week before last by supran and others that that characterizes what was known about climate change. Inside Exxon Corporation inside the scientific community in the Eason 80s the left hand panel here is is projected temperature trend on a lower line and the red line is the actual temperature trend. One is the CO2 trajectory that's projected and the blue line is the actual CO2 trajectory. The upper, the upper right panel shows the projected temperature trends from Exxon and peer open literature publications all of which were really good. The lower shows amazing 1977 reconstruction of the long term temperature change based on what we knew about the climate forcing from CO2. Next slide, and to put this in a slightly crisper context. Here are the temperature projections from the IPCC first assessment report 1990 and the third assessment report showing up hind cast and forecast part of the plot for the most likely evolution of temperature and what you can see is a projection that thick black line really runs almost exactly through the center of the observations that the squiggly colored lines and that even in 1990 35 years ago, our ability to project, not only the temperature response to CO2 but to have a reasonable idea of where we're headed in terms of CO2 emissions was pretty solid, and it's striking how good these estimates are. Next slide. And as a consequence, we have really good understanding of the relationship between future emissions and future temperatures, and, and we have what I would call an evolving understanding of the relationship between the temperatures and the, and the impacts. And I think that's where the excitement in the future is going to be the scientific excitement and where the overlap with this round tables work becomes so compelling. So back in the IPCC third assessment report in 2000 working group to proposed a bucketing of impacts into the five reasons for concern, one related to you, sort of large scale singular events. And I think that use of these five categories as a, as a way to provide a reference point for how we're thinking about the risks of climate changes has been incredibly valuable and the value that has really increased over time. And I think it's an important reference point as we think through, you know what's in and what's not in our, our current impact assessments. In the IPCC framing the risk went from not detected to the very high I think is our understanding of the implication of these risks as has evolved. The way I think about it is that the yellow category moderate risk means we're, we're pretty sure that we can adapt the red the high category means that they're real questions about the effectiveness of adaptation even transformational adaptation. And the very high the purple category is one where we're pretty sure we can adapt, certainly not at the global scale, even if some aspects of society continue on. And it provides a really useful way for asking where the risk come into the most focus where they're the most intense and where we have more work to do the next slide. Presents an overview of the way our our understanding of these risks has changed through time going all the way from 2001 to 2022 for each of the, each of the five reasons for concern. And the striking feature of these is that if you look across the, the to see line. So what you see is that in 2001, in general we considered the, the risks at to see to be in the moderate category, really sure we could adapt, and that the evolution of our understanding, since then has profoundly wrong about the magnitude of the risk to see, and even at 1.5 C and what you can see for unique and threatened systems things like rare and endangered species heritage sites, culturally important sites that it's clear that there's a transition from the red high risk to purple. Adaptation doesn't it longer work in the region of to see. We also see quite a profound drop in the in the level of alarm or an increase in the level of arm drop in the temperature of which the risk transition for the large scale discontinuities that Tim Linton has worked so much on and we were discussing earlier with the consequences of altered ocean circulation for climate in Europe, and this, this transition from thinking that to see was mostly okay in the, in the early years of the century from recognizing the profound risks that to see really is the accomplishment of climate and impact science over the last 20 years. Next slide. We wrapping up please. Uh huh. And the point I want to close with is really this point about the linear relationship between cumulative emissions and the total amount of warming that occurs and then persist for hundreds or thousands of years. And if you just advance one, you can see how close we are to the level of 1.5 if we account for double counting and if we account for ecosystem feedbacks were within a handful, probably three to five years of commitment to a warming of 1.5 and a commitment to the really unacceptable risks that we see in the, in the reasons for concern. So the motivation for bringing together the climate science and macroeconomics incredibly strong and the opportunities for mutual benefit from the two communities are incredibly strong. I look forward to comments and questions. So we're going to do some questions and you can raise your hand. I will. Okay, Bob. I would give you an open ended question Chris, having sat through the last five economist speakers what what do you think that are sort of where do you think that the frontier of climate science is that's relevant for the sort of economic projections we're talking about, but not as robust to say the, you know, the temperature predictions and the existence of the carbon budget. Where do we need more, where do we need more climate science or do we basically have enough climate science to get on with the macroeconomy. Yes, and yes, we need more and we have enough the big areas of progress in the last 20 years have been attribution especially single event attribution and a better characterization of the risks of extremes. But it's also clear that we're not at the stage where we're going to be providing accurate seasonal or inner annual forecasts of individual extreme events, and where the kinds of risk management tools that people have been discussing are going to need to continue to meet a foundation of the model. Rachel. Chris thank you so much for that bracing characterization of the latest science of you know, sitting through that. What comes through clearly is we're at a little over a degree Celsius and we're already seeing very profound impacts around us already or that have been unleashed was full impact we will see in the decades to come. And when you look at the policy side of macroeconomic side the signal is not detectable. So there is clearly something happening here a disjoint aspect to what the science is increasingly signaling in terms of urgency running out of time and an approach that largely a macroeconomic perspective is humming along in a business as you know incrementalist kind of approach and hence your point that this couldn't be more timely for a group like this to get together and connect some of those dots. But from your perspective sitting on the outside. What do you think is driving some of that mismatch is it model specifically or is it different rooms in which these conversations are happening where the power structures are different. The political calculus is different and what feels pressing in one room and another room there are other things like the interest of the fossil fuel industry that you pointed out from that supreme at all paper, become the dominant factor driving policy outcomes. I understand and I don't pretend to know the answer I think that one of the most compelling products of a group like this round table would be further thoughts on why we're not seeing more of the of the evidence and I think that the two things that that I would speak to are that you know, even though climate impacts are accumulating in in a compelling and discouraging way that they're occurring in the context of an economy that has all of the growth driving factors that that it's always had and continuing to operate and that the undetectability of the climate effects so far. It probably has some combination of temporal and and baseline effects as people been discussing. I also think that, you know, most of the impacts that we're seeing in extremes are still relatively limited in time and space. As the number of those impacts increase, I think we'll, we'll begin to see them scale in a way that, you know, probably won't be linear, and a lot of the future work that I'm looking forward to seeing is going to address this question of, of how responses to extremes interact. Eric. Thank you. Yes, I guess I was thinking along similar lines to Rachel but I'm going to say something which might turn out to be a comment but I'm going to try to make a question. So, we have to act rapidly. I've seen evidence of the sort that you've presented. And so this is the tension that I hold inside myself. We have to act extraordinarily rapidly. I want to point out that there is a bright, I'll start my video that there is a branch of economics, actually, development economics that has recommended rapid transformation of economies and there is some evidence about how to deal with structural change, rapid structural change, much harder in a, in a complex economy like, like our own but it's, it's there and it's not that there's nothing at all. But, but this, this is the challenge and this is why it's a comment this is the challenge for us. Those, those of us who are economists have to get away from backing off from rapid change. Because there's no option there there you can you can debate the policy but the physics is never going to debate with you. So that's just my comment but if you've got Chris if you've got words of wisdom to add to that I'd love to hear. Yeah, thank you for the comment Eric. Brad. Yeah, thanks Chris. So the question has to do with climate intervention. Both in the impact of climate likelihood and impact of climate intervention in what you presented here, but then the extension of climate intervention into incorporating into the macro economic models and how we might try to do that. We know that the climate effects of carbon dioxide are essentially permanent at least on a millennial timescale. And what that means is that there, there are two ways we could produce cooling. We decided we wanted to go that route one is removing the greenhouse gases actively from the atmosphere. And the other is preventing as much sunlight as currently enters the earth system from entering reflecting more that would be solar geoengineering and the CDR remove CDR is an increasingly important part of the mitigation portfolio. And that's the incentives in the inflation reduction act. And it looks to me like it will continue to build out as as a complement of all the other mitigation activities that are occurring. The solar geoengineering appears based on relatively limited evidence to be technically capable of decreasing the temperature, but not of affecting all of the consequences of climate change, including the certification of the oceans. And at this point, I think there's a very strong argument for learning more about solar geoengineering to see whether it might bring useful levels of temperature reduction in a context that were governable and were fair and were technically manageable. But at this point we're not there. And short of saying that there are answerable questions that need to be answered before we can decide whether solar geoengineering should be a part of the portfolio. It's hard to go beyond that. I don't see any more questions and I think we're on break time now. Thanks so much. Thanks, Sabrina and we'll reconvene at the top of the hour at 3pm Eastern with these next