Afternoon and early evening to some, thank you for joining us today for the first day of a three-day workshop on tipping points, cascading impacts, and interacting risks in the earth system. Given the number of participants that have registered, it attests to the importance of this topic and the timeliness and I'm very glad that you'll be here. I'd like to thank the committee and the National Academy staff for all of the work that they have done to plan this workshop. It's been quite an undertaking and also very enjoyable working with everyone. And also, thank you to the National Science Foundation for sponsoring it. In a little while, I'll give an overview, some context for our workshop, but before we go into that, I'd like to turn it over to NSF representative, recording in progress, Anjali Banzai and Candace Major, and then we'll learn some housekeeping rules for how we'll proceed today. Thank you, Kristin. Good morning, everyone. I'm Anjali Banzai. I'm Senior Science Advisor, Global Climate Change in the Directorate for Geosciences at NSF. I'm the Cognizant Program Manager for this project. It is a follow-on activity to the September 2021 NASEM report on Next Generation Earth System Science at the NSF. And that report laid out a vision for an Earth System Science Initiative at NSF that is bold, integrated across disciplines and forward thinking. I want to thank the NASEM staff and all the committee members, particularly Chair Dr. Kristin St. John for their efforts. Kristin was a member of the previous study, so she ensures continuity to this follow-on study, which is actually a deep dive on the topic of tipping points, cascading impacts and interacting risks in the Earth System. So again, we're looking at this topic within the Earth System Science concept. So we look forward to the results of this study, and it is crucial input through which NSF Garner's community input on emerging research questions that have significant societal impacts as well. And so I want to turn it over to my colleague Candice to add on what she might have to say. Good morning, everyone, or good afternoon, good evening. Thanks. I don't have a lot to add to what Anjali said. Just to thank both the Academy team and the team that was working to put together this particular workshop. Anjali and I have been working with the academies over a number of years now, first with the Earth System Science Study, and now with this series of workshops. This is the first in a series that's a follow-on to that Earth System report, which has been very impactful at NSF in the geosciences and really across all of the directorates. So again, thank you, and I'm really looking forward to the next few days and hearing what everyone has to say. I'll pass it back to Kristen St. John. I think we'll go to Margo now for some housekeeping information. Margo, I believe. Let's start off with just a land acknowledgement. So this workshop is actually a virtual one, but the Academy's headquarters is actually physically housed on traditional land of the Denkakta and Anikasia and Piskatawe people past and present, and just wanted to bring that to everyone's attention. A few housekeeping items is that we will be using Slido for the entire three days of the workshop. Here is a QR code that you can scan, and there's also the actual website and a number to enter in. We will be taking Q&As here from all the audience. So anyone who's participating, please feel free to use the Slido. In addition to, we will be using Slido to engage during some of our breakout sessions. And with that said, I'd like to thank you all for attending. We're very excited. Thank you, Angeline, Candice, and Kristen. And I will turn this back over to Kristen. Thank you. Okay, thanks, Margo. I think I'll touch on the I'll touch on the agenda in a moment. I think I've got some background slides that we're going to look at. Okay, great. As they're getting them set up, we'll be ready in a second, I'm sure. Okay, I think we're all set now. Fantastic. Okay, thank you. All right. Well, thank you and welcome again to the workshop. In order to provide some context for what we'll be doing for the next few days, I want to take some time here to provide some background on the motivation for this workshop, which Angeline and Candice have already referred to, a consensus study report. I'll describe that a little bit more for you. I'll also introduce the workshop by walking through some key elements of the statement of task and connecting the task to the content and organization of the workshop. And then finally, I'll present some results from a short pre-workshop poll that we think can be used as a starting point on community ideas about tipping points. Next slide. Next slide, please. Thank you. Okay, so the concept for the workshop emerged out of the 2021 consensus study report, Next Generation Earth System Science at the National Science Foundation. Now that report focused on defining a vision for Next Generation Earth System Science, describing key characteristics needed for studying the Earth system, identifying opportunities, and recognizing barriers to progress for achieving that vision, and then the committee also made recommendations to NSF on implementation. Now today, I'll just share parts of this. I want to share the study premise, the vision, and the key characteristics as these connect to the framing of our workshop this week. Next slide. Okay, the study premise was that there needs to be an integrated approach to understanding the Earth systems. Integration between natural and social processes are essential components of that integration. And as you can see, if you look at the vision statement, these same concepts are essential to the vision for a Next Generation Earth System Science, which is a Next Generation Earth System Science explores interactions among natural and social processes that affect Earth's capacity for sustaining life now and in the future. Taking an integrated approach and focusing on natural and social processes are also key components of the workshop this week. Next slide, please. Okay, the committee for the consensus study report identified six key characteristics of an integrated approach to the Next Generation Earth System Science. These are two advanced research, both curiosity and use inspired research, and across a range of scales across different temporal, spatial, and social organizational scales. It is to facilitate convergence across many different disciplines to help inform solutions to Earth systems related problems. A key characteristic is to ensure diverse, inclusive, equitable, and just approaches are unfolded into the research done for Earth systems science and the outcomes of that research as well. We should be using observational, computational, and modeling capabilities in a synergistic way. And it's important to educate and support a workforce with the skills and knowledge necessary to be able to do this work and then to be able to communicate about it. Several of these characteristics ultimately link to the framing guidelines and driving questions of our workshop this week. For example, today we will consider change over different temporal scales in the geologic past and in the recent past. So that ties to key characteristic number one. And we will hear perspectives from geoscientists, economists, and social scientists. So that ties to characteristic number two. Next slide. So I won't go into the details of the report recommendations to NSF here, but two overarching takeaways from the report are that broad perspectives from a range of disciplines matter in addressing contemporary societal challenges that involve the Earth systems. Also, inclusive, open exchanges of information and shared learning are definitely necessary. One click please. Thanks. So thinking of our workshop topic, tipping points, cascading impacts, and interacting risks in the Earth system are certainly contemporary societal challenges and research will benefit from these approaches outlined in the consensus study. Next slide. As was mentioned earlier, our workshop is part of a series of workshops or roundtable discussions related to that consensus study. Following our workshop starting next week, there'll be the second opportunity to engage. And that's an open roundtable discussion on macroeconomics and climate related risks and opportunities. Number three on the list, the Climate Intervention Committee has just formed and we expect a workshop in late spring. And a climate and human migration workshop is in the pre-planning stages. Okay, well with this as background, what I'd like to do is provide an introduction to our specific workshop, tipping points, cascading impacts and interacting risks in the Earth system. Next slide. So it's been a real delight to work with my fellow committee members and the Academy staff on the workshop design. As you can see, this committee has a broad range of expertise and I'm actually quite humbled by their knowledge and their ability to share ideas across disciplines. I've learned a lot from them. I think it's been a very engaged and knowledgeable group. In addition to Marco, Patricia and Sabat, there are also several other Academy staff helping us today, given the high number of registrants and the number and the online format. So thank you to all and also a very big thank you to our speakers and to all of the participants. Next slide. Okay, so what was the task laid out for us that brought us all here today? So our committee was tasked with the following. We were to plan a workshop to bring together experts to consider this topic, tipping points, cascading impacts and interacting risks in the Earth system. We should be incorporating key characteristics laid out in that National Academy's consensus study report. We are to apply Earth system science approaches to explore understanding, prediction and preparation for tipping points in the Earth system. We strive to cultivate connections among the transdisciplinary research community and address specific questions, and we'll see these in a little bit, address specific questions that help prioritizing research and identifying opportunities, barriers and possible strategies. And then ultimately, the presentations and the discussions that we'll be having over the next few days will be compiled and published in a workshop proceeding. One click. So I believe you'll see each of these components in the structure and the content of our workshop. In particular, the statement of task questions, the specific questions that number five alludes to. That plays a central role in the plenary and breakout discussions and idea. Oh my goodness, excuse me. The sharing of ideas, excuse me. And we think that those ideas and the discussions will help address questions that we also see in the approaches to explore understanding, prediction and preparation for tipping points. So five and three really relate well to each other. But before we go forward and look at those specific questions and the structure of the workshop itself, I wanted to comment on number four, just one click. And number four, I think deserves some extra attention because forming transdisciplinary research teams or bringing transdisciplinary communities together is in and of itself very, very challenging. It's been called a wicked problem. And I think there's so many who I think there's some other sounds in the background right now. I apologize. It's been called a wicked problem. And therefore I want to situate the workshop in a theoretical framework that might be useful. So next slide. Okay, can you hear me okay? Okay, thank you. Okay, so the model that I find useful is an older one. It's from Hall and others. It's a four phase model of transdisciplinary team based research. The four phases being a developmental phase, a conceptual phase, an implementation phase, and a translational phase. One click. Okay, I think that perhaps this workshop best fits, but not exclusively in the developmental phase of transdisciplinary research and maybe a little in the conceptual phase as well. So if you look at the list of principles or characteristics in that green box, I think we can make some connections to what we're striving to do and how we've come together today. Regarding goals, here we aim to establish a shared understanding of a scientific and societal problem tipping points. Regarding team types, the assembled group today may be viewed as a community or maybe a network. Maybe perhaps even in some sense or at least some subsets of our community might be seen as loose advisory groups. Regarding process, that third or final column in the table, we are working towards a shared mission and goals centered around or system tipping points as laid out in the statement of task. And by having natural scientists, economists, other social scientists here, we hope that the workshop will help us develop what they call critical awareness of other disciplinary perspectives and approaches. And we can externalize group cognition, another term in this model, via the workshop report that will be produced. Finally, we aim to learn from each other in an environment of respect and openness, which I think will allow us to build these connections with each other and move forward the concepts of transdisciplinary research. Next slide, please. Okay, so thinking about the content and structure of our workshop, so there was a pre-workshop poll. I'll talk about that in a moment. But the workshop itself is spread out over three days, as you know. That's it is intentionally designed so that each day is guided by one or more questions that were set out in the statement of task and that connect back to the next generation versus some science characteristics. So the questions are laid out there. I won't read them, but I'll highlight a couple of the themes within them. Following an overview of tipping points, we'll be taking a historical analysis of past tipping points over different time periods. Then we're going to have breakout sessions and discussions where we can look at key outstanding research questions and barriers and opportunities in the context of these historical perspectives. We also, regarding day two, we also asked NSF for guidance on scope, you know, to help us give some boundaries to what is a very, very large topic of tipping points. And we were guided to incorporate a U.S. focus, and we can really see that in our day two agenda. We'll look at different regional perspectives on tipping points and cascading impacts, and then have discussions and opportunities to share your ideas using Slido on the tipping points, cascading effects, interacting risks that are critical to these different geographic areas. And what we hope in those discussions that we'll also see some opportunities for transdisciplinary research moving forward. And then day three focuses on research priorities and opportunities that broaden perhaps how we have traditionally thought about classical research in this area. So we want to benefit from insights, from indigenous knowledge, and also considering the cascading impacts in the intersection with environmental justice. And then for the second half of that day, we'll be looking at three questions that are almost verbatim from the guiding questions in our statement of task, looking at research priorities, how they can be identified, conducted, and how strategies can be designed in a manner that's inclusive and equitable. So that ties back to some of the plenary comments earlier in that same day. Also looking at new capabilities, so some of the technological side of this and computational sides. And then finally looking at how to advance across natural social computational engineering sciences, how that integration can happen more. Okay. Next, what I'd like to do is comment on that pre workshop poll. So if we could go to the next slide. Okay, so there was a short poll that was put out. And it was shared with invited and early registered participants. I believe about 60 people received the poll, and I think we had about 20 or so responses. So it's a starting point here. The results can serve, I think, as a starting point for community perspectives. The questions that were asked in the poll are those that are shown here and include some of the same questions that we'll cover over the next few days. So the committee and staff reviewed the responses. We saw a few themes. And so I'd like to share those with you now. Next slide. Okay, so the first question that was asked was briefly summarized what tipping points in the earth system mean to you. And what we saw were kind of two different directions, two different themes that responses were taking. One of those directions was more of a technical quasi mathematical definition approach, sharing ideas of how switching from one regime state or equilibrium to another crosses the threshold. So that kind of definition of tipping points. The other theme that we saw in the responses were looser narratives about the impact, like the economic or social impact of crossing tipping points. And there are two examples there. The example of the more technical response is something like rapid nonlinear changes to an alternative state, which are often irreversible. Pardon me. An example of the more narrative approach that focuses on impacts would be something like ecosystems and other earth system components can become destabilized and enter configurations that are detrimental to human civilization. So these are related, but kind of take two different approaches to responding to the meaning of tipping points. Next slide, please. The second poll question asked one of the one of the guiding questions essentially for this whole workshop, and it gives us a starting point here. What are the key outstanding research questions on natural physical, chemical, biological, and social tipping points? They're interacting risks and they're cascading impacts. So when we look at the responses, not everything was posed so much as a question. So rather than showing you these in a question format, I'm sharing them as more like research topics, topics that could be put into a question format. And we essentially saw six different bins that the responses fell into five or six. I'll comment on that. So one topic for outstanding research questions seems to center around conflict and social responses. Another seemed to center around better evidence, reducing uncertainty, improving models, and then a very closely related one. So whether it should be its own topic or maybe it's a subcategory of the one I just described is developing early warning systems. A fourth topic for key outstanding research questions focused on this grouped category of policy responses, institutional responses, resilience, and management. And then the fifth category of potential key outstanding research topics focused on interconnections between tipping points, and then finally communicating about the issue. Okay. Let's move to the next slide, please. A third question in the pre-workshop poll focused on what are the major barriers and opportunities to accelerate progress to advance these areas of research. And I'll read these and then point out some commonalities. So for barriers, some of the barriers included lack of data, especially the social science data, missing processes, and limited resolution of models versus system complexities, and just the difficulties of doing interdisciplinary or I'll add here, transdisciplinary research. There are also opportunities though with integrating models, access to big data and Earth observation data, and interdisciplinary connections that can be built. So I think it's interesting to note that both data and interdisciplinary span both the barriers and the opportunities. Next slide, please. Okay. I've got a few slides here. This is the first of three that focus on some grouped topics that we asked respondents to express their interest in to rank their interest. So the interest in these topics were actually quite similar. Of most interest was focusing on cascading risks from the recent past, the last century, that would impact recent civilizations and communities. And then fairly even was interest expressed in longer-term perspectives, like tipping points in the broader scope of Earth's history, and also cascading risks from past extreme events, let's say over the last thousand years that could impact civilization. So these are all topics that will be addressed today. Next slide, please. Okay. Thinking about our agenda and how we're organized for tomorrow, how we'll have some geographic focus, we asked for interest in different geographic areas, excuse me. And there was interest in all of these areas. The Arctic had the most interest, was of high interest. And then there was interest in all of these other areas in the coastal U.S., the American West, and the Great Plains. Next slide, please. Okay. Looking at some of the topics that we'll be focusing on on day three, we asked about strategies for moving forward. And the topic of most interest was developing strategies to advance transdisciplinary research, and that was one of the reasons I wanted to share that model a little earlier in my presentation. Also of interest, developing new conceptual experimental organizational research capabilities, and then finally developing research strategies for inclusive and equitable participation and engaging stakeholders. Next slide, please. Okay. Finally, I'll share some of the demographic data from the poll. A great number of natural scientists expressed interest in the workshop. And of course that ranges across a great number of different disciplines within the natural sciences, physical, chemical, biological, and so on. But importantly, social scientists, which include economists, political scientists, sociologists, as well as people from other research fields, for example, applied math, and then the broad scope of system science also expressed interest. And we're very glad you all are here. Next slide. Most people that responded to the poll were in academia, not surprising given that the workshop is part of a national academies program. But it's also good to see nonprofit governmental and non-governmental organizations represented. Next slide. Finally, we're really pleased that the workshop topic is of interest to people across all career stages. I don't think we could have asked for anything better here. We see that early mid-career and late-career are fairly evenly split with representation, at least based on that initial poll. And we're also very glad to have emeritus and retired faculty with us as well. And I think I can wrap it up here. There might be a little time if there are any questions, but if not, I'll turn it over to Dorothy Merritts, who will introduce our first session and the speakers. Thank you. Thank you, Kristen. Good morning, everybody. I'm introducing the first session, an overview on tipping points and expert responses. There are three people who will be presenting over the next 30 minutes. At any time, you're welcome to contribute questions on Slido. So if you have any questions about how to use Slido, please let us know soon. But you can post questions there. You can also upvote questions to raise them to the higher rank, having more people interested in that question. We will be monitoring those questions and then after the presentations, we'll begin addressing each of those. The presentations are going to be given by Dr. Tim Lenton, Director of the Global Systems Institute and Chair in Climate Change and Earth Systems Science at the University of Exeter. After Tim presents, then we'll hear from Dr. Jeffrey Rubin, Retired Emergency Manager, and then a response also from Dr. Bob Kopp, Professor and Co-Director of the University Office of Climate Action at Rutgers University. So we'll begin with Tim. Thank you, Dorothy, Kristen, and all of the rest of the organizing committee and support team for giving me the first speaking slot. So my job is to introduce a given overview of tipping points in the earth system. So I'm just going to share my slides. Oops, in fact there's a little bit. Yeah, so I want to start with a simple toy model of a system that I'm going to force past the tipping point, just to get us keyed into what we're thinking about. So this is a system with two alternative stable states. It started as denoted by the ball in the left-hand one. But over time, I'm forcing that state that it's in to become less stable or less resilient. That means the damping feedbacks that maintain stability are getting weaker all the time and the reinforcing feedbacks that can propel change are getting stronger until at some point they're going to take over there and cause a self-propelic change of the system from the one based on attraction to the other. If I just run it one more time, I'll add that if you watch the ball closely, you can see some characteristic behavior before the tipping point. A given nudge is going to move the ball further than nearer you are to the tipping point. So the variance in the system goes up. But also the ball recovers more slowly from perturbations because the slope is declined. And that means one sort of position of the ball or time point becomes more like the next. So the autocorrelation of the system in time goes up. And those are generic early warning signals. So a tipping point that we'll come back to. So tipping points are recognized across a whole range of earth systems, climate systems, and ecological systems. And I put them on a bunch of those on different time and space axes here. Gold, as you can see in the key, is denoting big-scale climate system tipping points. Blue, green, and sort of gray are different ecological realms of tipping points or regime shifts as ecologists would call them. And then red are tipping points in the social system, some good, some bad. And right in the middle, the one that I guess we're all here to try and avoid, another civilization collapse. Well, I'm going to start up in the top right, but the torque's going to migrate down, down leftwards. But let me start with some tipping points in the deep history of our planet. And this is a kind of cartoon summary of oxygen levels over earth history on the y-axis and time through earth history on the x-axis. And the key point is that there was a profound tipping point halfway through the planet's history that geochemists call the Great Oxidation Event or episode when we went from that anoxic atmosphere to an oxidizing atmosphere. And it was irreversible. We also think it was abrupt, although it might have been oscillatory in the transition. There was a second major tipping point much more recently in earth history, only 600 or 700 million years ago, still seems like a long time ago, when there was a second rise in oxygen. But there were also at least two so-called snowball earth events, which involved profound climate tipping points to an ice-covered earth and then snapping out about into a kind of hot house earth. If we zoom in much more recently to the last 66 million years, the Cenozoic era, well recent work has shown rather elegantly that you can extract evidence that there are like four different global climate states that the earth has sampled, if you like, or been through in the last 66 million years, dubbed the hot house, warm house, cool house and ice house, with sometimes abrupt transitions between them. For example, from the sort of warm house of the Iocene at 34 million years ago, the earth went into the cool house of the oligocene with the first major growth of an ice sheet on Antarctica. Now, much more recently, we've gone into the ice house of glacial interglacial cycles. That was a sort of tipping point into the ice house. There's another tipping point around 900,000 years ago where we went from 41,000 year to 100,000 year ice age cycles. And then if we look within the last ice age, well, we see just in the last, zooming into the last 80,000 years here, we see the iconic example of abrupt climate changes. So this is a proxy of temperature as recorded in an ice core in Greenland, and it's showing 20 numbered so-called dance guard oscar events in which the climate warms up to 15 degrees centigrade at the ice core site in Greenland in a time span that can be as short as one to two decades. And those abrupt climate changes had global effects, most pronounced in the North Atlantic region, but seen throughout the Northern Hemisphere and with echoes in the Southern Hemisphere. If we zoom in just to the last 30,000 years of that record, we start to see some more of the structure. Arguably, we see the slowing down of climate fluctuations, particularly after this boiling, all around warming 14.7,000 years ago. Perhaps a full runner or warning that we're going to snap out of the last ice age, finally, about just under 12,000 years ago. And whilst we all as paleo climate people like to think that the Holocene the last 10,000 years ago or 10,000 years or so is more stable, and it looks that way in this Greenland record. Actually, in the tropics, we know there are abrupt switches on and off of monsoon systems that are some of which are correlated with the rise and fall of past civilizations. So what about the future? Well, back in September, we published led by Dave Armstrong and McKay a synthesis of around 230 studies and drew up a fresh map, a list of what we call the tipping elements, the bits of the climate system that we think there's good evidence to think could be tipped by global warming this century. We split that into two categories. And this first category is the global core climate tipping elements, where if they tip the whole you feel it in the whole climate system. Some of these have been on my maps for 15 years or so now, but some of you like a tipping point in the collapse of convection in the Labrador Sea, which could happen at low temperatures unfold in about a decade, given like a transition to a little ice age like climate in Europe, up to a foot of sea level rise along a northeast seaboard of North America. And the models would suggest would disrupt the West African monsoon. We also have a category of what we call regional impact tipping elements. So you tip these, maybe you don't feel it or see it in the whole climate system, but my word people have got good reason to care about it. Because for example, a tipping of the loss of on the large scale of low latitude coral reefs. Well, 500 million people or more depend on them for their livelihoods. We also have regional monsoon systems, for example, in this list. So part of the evidence to put things on these maps comes from evidence that these systems have tipped in the past, particularly the Great Atlantic Ocean overturning circulation. But also some of the information comes from future model projections. So this is a summary of where do abrupt shifts happen in climate model projections of the future from the last sort of penultimate generation of climate models. And so you see spatially the letters denoting where they happen. But the color scheme shows you what warming level they happen. And if you're watching closely, you'll see that a bunch of abrupt shifts happen at relatively low levels with global warming above pre-industrial in the model worlds, including that one I mentioned in the Labrador Sea, but several others as well. Then we can also learn something from offline models. So models of slope systems like the major ice sheets like this one, Antarctica, subjected to a steady warming and kept close to equilibrium. You see it around two degrees centigrade of global warming there. The prediction is that the West Antarctica ice sheet is unstable at equilibrium. It'll take a while to melt, that's for sure, but it's the tipping point is just around two degrees C. And if we keep warming up this Antarctic model, keep holding it close to equilibrium, well, we lost the Wilkes basin somewhere in the simulation, another marine grounded ice sheet. And now at about seven degrees C of global warming, the whole East Antarctica ice sheet basically goes. So that's another source of model-based evidence. And then we have what we actually see in observations. So this is my potted summary of some of the observational evidence that key tipping elements are experiencing accelerating change in the wrong or the undesirable direction, including the West Antarctic ice sheet, where we can't rule out that part of it has passed a tipping point, part of it that drains enough ice to raise sea levels by about 1.3 meters worldwide. Similar, I'm afraid, evidence of accelerating ice loss in Greenland. And then also, distance slowing down, being inferred in the Atlantic's great overturning circulation, as well as the well-known accelerating loss of Arctic sea ice and some unprecedented droughts in the Amazon. So changes in the mean state of systems, as summarized here, can give some clues to where the tipping might be approaching. But if we remember the movie at the start, looking at how the fluctuations of systems of behaving is also informative. And if a system is heading towards tipping point, we expect to see the variance in the fluctuations increasing in amplitude, and also the fluctuations to become more persistent, which we measure as an increase in something we call AR1, or time-autocorrelation at lag1. And so that variance is the middle row here. Autocorrelation is the bottom row. And the top level is some observational data with the mean trend line in red removed before analyzing for the other statistics. And we're looking at how the Arctic sea ice September extent shows clear signals of destabilization consistent with heading towards the tipping point as does the central Western Greenland ice sheet, as does the overturning circulation of the Atlantic. These methods cannot tell us in any sense how close we are to the tipping point, or at least they don't tell us that here. But in the case of the Greenland ice sheet example, the curvature in the data suggests tipping point would be imminent for that part of that ice sheet. We can also do this with a remotely sensed data. So now for the Amazon, we look at fluctuations in vegetation optical depth, it's called, which is a kind of proxy for biomass of the Amazon forest and its water content. And as the colors were getting lighter through the 1990s, that was the Amazon normally getting more stable, but they're getting darker now through the 2000s up towards the present. And that's a very distinct signal of destabilization, or we would say loss of resilience in the Amazon rainforest that's most pronounced and consistently over the last 20 years. I'll just flick on and summarize that in a slightly different way. Where the colors are red here is the strongest loss of resilience and the observational data over the last 20 years. Where they're blue, they may be gaining resilience and gray is neutral. We could correlate the places losing resilience with being biased towards the drier parts of the forest and being biased towards places closer to human activities, which all makes kind of intuitive sense if a little sobering. So all of these sources of information are feeding into this synthesis of the 230 papers that we put together to try to summarize in the birthing embers. Where in terms of global warming on the y-axis we assess the tipping point to be for all these tipping elements that raid along the bottom. Where this starts to be say one model that expresses the tipping point that marks the lower end of the color scale like white to yellow and the last model to tip if you like would be the dark red marking the top of the color bar and the black dotted lines are our subjective best estimates of where we think the tipping point might be for each system. Suffice to say that the current level of about 1.2 degrees centigrade of global warming we think five systems are at some risk of tipping. The first four there in the Labrador Sea. At 1.5 degrees C of warming our best estimate is that tipping could become likely in the greenland ice sheet, west Antarctic ice sheet, low latitude coral reefs and a chunk of the boreal permafrost. Each of them has their own characteristic timescale over which change would then unfold. It's still quite slow in the ice sheets but considerably faster in the coral reefs and a really sobering observation is that current policies are taking us to about two and a half or 2.6 or 7 degrees centigrade of global warming which if we were right would suggest 13 of these tipping elements are at risk. Three of them we'd be fairly confident we'd have already tipped. One, two, three, four, maybe well four or further ones would be at high risk and there's another six at some risk. So that's what the picture you get if you consider them in isolation these tipping systems but of course the earth system is interconnected in a way that tipping on the thing can influence the likelihood of tipping another could go in either direction but unfortunately there are some cases where the evidence is building that tipping one thing makes tipping another more likely. So the incredible warming of the Arctic linked to the loss of sea ice is making it snow and rain more and the Arctic adding fresh water to the North Atlantic it's accelerating the melting of the greenland ice sheet adding fresh water to the North Atlantic. Both of those sources of fresh water are contributing to slowing down the Atlantic overturning circulation which is at risk at some point of tipping and we know from Earth's history that when you slow that down you disrupt them on soons around the tropics including in the Amazon West Africa and India you leave heat behind in the sub-motion which is the major risk factor for the West Antarctic and the East Antarctic ice sheets. So that's the information synthesized on the likelihood of big-scale climate tipping points if we wanted to do a risk assessment we'd want to know what are the impacts of passing those tipping points as well as what's the exposure of people in different places and to those impacts as well as other ecosystems and to me it's amazing how little research overall has been done on the impacts of passing tipping points this table is just there to give you a flavor that we have some information and some judgment but the only one that's really been studied in considerable depth is a collapse of what's called the Atlantic meridional overturning circulation or AMOC for sure and in climate models several groups have caused the tipping point in this system to happen and then look to the consequences so what I'm going to show you is what happens if a tipping point happens in the Atlantic overturning circulation on top of the 2.5 degrees centigrade of global warming that we are heading towards on current policies worldwide one on the left we see the overall pattern of temperature change and on the right we see the even more alarming pattern of precipitation change and the scale is in percent here so you see extraordinary drying in parts of the planet including across West Africa and the Indian Monsoon region but also across large parts of Eurasia including massive crop growing regions linked particularly to the tipping point here in its spatial signal so that begs a few straightforward questions on what would the impacts be on some sort of more human systems well sorry to be parochial for a second but as I'm in the UK and we actually have a good econometric model of land use decisions in the UK we could feed the climate tipping point and global warming scenario into that model and basically show that if this climate tipping point were to happen it would eliminate arable farming in the UK unfortunately that would be the least of our worries because the drying is that's causing that disaster for arable farming is so acute in the southeast of the UK that there would be a massive water deficit for most of the but the you know most densely populated parts of the UK and we be looking at a massive infrastructure project to try and pipe water from where it's still raining on the west western seaboard of Great Britain looking more globally though this combination of global warming and this specific tipping point would have profound implications for the viable area over which you could grow the major staple crops particularly of wheat and maize rice is a kind of mixed picture that here we see in purple places where suitability for growing the crops is declining green where it's getting better well it's a double whammy effect basically global warming is bad for wheat and maize production the tipping point of the amok collapse is also really bad for wheat and maize production and their effects are at least additive if not mass applicative so that we more than halve the viable area for growing wheat and maize worldwide and sure i would surmise that that would cause a food security crisis and no doubt if you tip a large bit of the climate system it's going there's going to be interactions to tipping points on other scales of system in this case kind of downward tipping cascades where tipping a big system like that makes tipping a whole lot of littler systems more likely which is sort of one of the many things summarized in this elegant table from a paper by Huang Rocker and others which also explores the possibility of very occasionally you can have tipping point cascades from in the other direction from small systems to large systems although that's rarer but there's a whole categorization of types of coupling across climate ecological and social systems and interestingly earth history even as we begin to stare at it in more detail shows us that when there were episodes of past abrupt climate change surprise surprise there was coupled with abrupt changes ecosystems and also abrupt change in early societies as Victor Bobkin and others summarized in a recent paper and here is a little schematic from changes observed 14.7 thousand years ago in the abrupt warming that started what's called the following hour odd so for sure we we've got reason to get together to talk about cascading tipping point risks and i just pulled this out of the world economic forums global risk report that was published last week ready for the world economic forum in dustboss this week as we speak and you may note that the environment and the climate are in there in the cascading risk landscape but they do seem rather off to one side very tightly coupled the you know ecology and climate amongst itself but rather weakly coupled you might argue to the rest of the network of risk so i feel like we still have some work to do perhaps in this transdisciplinary sense to point to explain to everybody how fundamental tipping points in the green stuff could be for the rest of the stuff in but at least we're all gravitating towards the need for that research so looking ahead let's hope we have a productive few days together on this topic but i'm also part of a group that's pulling together a community and producing a state of tipping points report ready for november's conference of parties number 28 um and we're also doing a special issue of a journal if you're interested to submit your work on this important subject so just drop me a line at that contact address if you're interested in joining either of those activities to summarize um exceeding one and a half degrees integrated global warming could trigger multiple climate tipping points there are general early warning signals before reaching a tipping point and they've been detected in several of these tipping elements recently the impacts of the most studied climate tipping point are severe and additional to the impacts of global warming and i i would add possibly existential risks and clearly tipping point interactions and their cascading impacts across systems and scales further add to the risk they pose so plenty of reason to meet together thanks for listening thank you tim an excellent overview and already the questions are coming into slide oh everybody else please add your questions or make a choose some of them to say you'd like to have have them raise rise in rank we're not going to have responses from jeffrey rubin and then bob cop so we'll turn it over to jeffrey first thank you great i'm going to take us from the global level down to distinctly local level that's where a lot of the changes that we're talking about are going to be felt most intensely and it's also where a lot of the significant adaptation actions are going to take place next please figure this is a good way to frame it up some context as landmark paper in lancet from 1971 nice to play on words i'll let you read the full quote on the inverse care law i'll just do the first sentence the availability of good medical care tends to vary inversely with the need for it in the population served and you could substitute for medical care social services other basic needs just think of it as a proxy but bottom line is that when we're talking about critical services the folks who most need it may not be most likely to get it and that's also a useful concept not just for the disproportionate effects of climate change on the population but also the challenge in obtaining resources or even even choice when it comes to effective adaptation whether it's ability to move or say in where one lives in the first place or access to funds etc next please and i appreciate the national academy staff thanks patricia for posting the links to all these in the chat for those interested in following up these are four examples of local adaptation choices in various parts of the u.s states and territories the first two are kind of an interesting comparison the first from colleen haggarty of the washington post and the second from smantham albinado and kendra pierre lewis writing the city this is on the 10-year anniversary of sandy the 10-year anniversary last fall on what different stretches of the the northeast the u.s coast did just a just a few miles apart the first in new jersey using a concept of mostly managed retreat with a living beach approach and then a new york city kind of the opposite where we have dense development in a high-risk area using a bit of accommodation mostly what femo would call protection or defense in terms of hard defense for for new buildings but new york is also dealing with a major housing shortage as are many urban areas it's not simply a single problem and these are just just two small examples uh meggy ride rigas in eos detailed what perico is doing to address a host of of environmental challenges most of them either directly related to climate change or at least magnified by climate change perico being a territory does not have the same choices in resources that u.s state would and being an island pretty much every hazard is magnified last i'm on the list is an ongoing project with the national academies on managed retreat in the gulf coast region in the u.s looking specifically at texas luciana and florida at addressing the incredibly complex issue of large-scale managed retreat as opposed to simply rebuilding uh post disaster in the same area right away just in time for the next disaster but the the economic and political and social decisions that go into that are incredibly complex the people who can leave generally do the folks who don't have the same degree of choices are left dealing with whatever faces them next please this is the portal page for uh state of oregon's wildfire response and recovery uh i'll clear attention to the five columns below the the header particularly the second to the left you can see the circle stat on destroyed homes from the september 2020 fires uh and i guess tim i'll i'll go hyper parochial because this is this was something we were directly involved in here um but uh over half of that destroyed home figures was in a single county jackson county jackson county lost over five percent of their entire residential building stock in those fires and that is a phenomenal amount it is difficult to comprehend it doesn't seem like a lot uh almost all of them would be what we would call uh affordable housing similar to what happened say paradise california with a campfire in 2018 you don't just fold spare housing off the shelf or something like that again the people who have choices can move along the people who don't are left dealing with a really bad situation for years to come and this is still an extremely challenging environment next please so finish well i think of some some useful overall concepts um you know it's great to get easy victories and and make some some quick easy changes i think most of the easy choices are kind of past us now uh we really have to deal with what i can't claim credit for for this the high hanging fruit um if these climate change and climate change adaptation are incredibly complex long-term expensive multifaceted problems and they are going up against other incredibly complex long-term expensive multifaceted problems we're not going to get easy victories and if we don't focus on the people who are least likely to be able to navigate this on their own we're simply not going to come up with with workable solutions if we focus on the most vulnerable among us then it will probably cover everybody else too so maybe we can call this trickle up or you know maybe maybe the trickle concept will actually work for the first time whatever we do in order to make it relevant uh for not just the policymakers the decision makers but also the people on the receiving end we as scientists have got to do better than simply well we just explain it better folks will go along so i'll just point to the pictures in the bottom both of these are from the Oregon Convention Center uh which is also the outside which is my my zoom backdrop uh the left is the fires in 2020 the right is i believe it was our first large-scale overnight sheltering in the Portland metro area for a heat event this was the the record setting heat dome in june of 2021 we killed hundreds of people in the pacific northwest he kills more people than any other natural hazard in the us and that's even with the typical undercount of those statistics these types of pictures are going to be recurring repeatedly if you've never been in an emergency shelter i guarantee you people don't go there for the coffee this is a resource of last resort and this is what we need to keep in mind as we move forward thanks thank you jeffrey and now we'll turn to the second response from bob kopp thank you dorthy um and thanks to tem for a great overview talk um tem's work has really been seminal in this space and so i want to preface what i'm going to say which is really going to be the devil's advocate um my response um that's a large part because i think critical views need to be aired in this discussion that we're having in cautions taken into account at an early point um so i just want to start by saying like i think tem's work over the last almost you know 20 years in this i think really has had a quite fundamental effect on our scientific understanding that said um i do want to take the skeptical perspective a little a little not because i don't think we need to better understand the sort of large-scale elements of the earth systems that the term tipping points is often attached to not because i don't think we need to understand how they interrelate with another but because i'm concerned that the tipping points framing um is an example of communication choices driving the science rather than the reverse and i i do want to know this is the first new national academies has been working in the space for over 20 years this is the first workshop i think with tipping points and the title as opposed to abrupt change um so let's talk about that term for a minute the term tipping point is a metaphor and i would argue it's a metaphor that cannot be separated from its popular understanding this is a term that first entered the academic literature in the 1950s from the sociological work on housing segregation but was relatively obscure and popular understanding until the late 1990s when if you look at its use say in google ingram it really starts experiencing a tipping point uh has a result i think it's pretty clear to say of the writings of malcolm gladwell in the new yorker and then in his books and it was after this popular tipping point uh that the term was adopted into the climate literature has a sort of initially as a primarily as a metaphor peer reviewed climate publications began using the term around 2005 when we were prepping for this session i think jeff said well we aren't going to talk about malcolm gladwell right um but i would argue that so long as if you search for tipping point the first 30 or so searches are either malcolm gladwell or in times religious preachers um i don't think that can be avoided so i think as we as we talk about critical thresholds in the air system as we talk about in a related system i think it's an open question whether using the term tipping point in that metaphor brings more light than shadow um when we communicate to the broader public um you know we understand i think in this group that's one of the things we call tipping points for instance tipping points in the green light ice sheet are things that may commit us to multi meter change but that multi meter change may play out of a many millennia which is not necessarily a connotation uh if you go back to say gladwell's usage or the endpoint preacher in times preachers usage um that is well understood and i think it's also a case that can simply be confusing for instance armchang at all do through their impressive synthesis present a case for the significance of one and a half degrees c with respect to tipping points but median activists were talking about one and a half degrees c has a tipping point well before there was analysis like that and some go further even referring to one and a half degrees c as a point of no return for the climate uh in a sense that gets you know i think raises a lot of concern about the efficacy of mitigation uh without necessarily being particularly tied uh to scientific understanding so one thing i think that is relatively missing in this space is a very limited literature on how the term tipping point affects public understanding i did find one recent study uh by felix fromanski and his colleagues in 2022 that did find evidence that sort of he used non-linear portrayals of climate risk they didn't even use the term tipping points in their study but that talking about non-linear uh non-linear climate risk do not affect uh perceived risk characteristics such as the catastrophic potential climate change or the controllability of consequences second concern so even if the term tipping point is underpowered as a communications metaphor like the fromanski study suggests should it be affecting our our actual decisions about mitigation or adaptation i would say i think it certainly should be affecting how we choose to study the integrated earth system i think it's quite useful to think about these interacting systems but i'm a little skeptical that it actually should have any effect on our mitigation policy uh and that global scale tipping points as opposed to regional ecosystem tipping points should should have that much effect on on local adaptation so why well one because there's this broad uncertainty you know you saw those bars from the armstrong study um once you smear out tipping points they don't look necessarily that different from a benefit cost analysis or from gradual climate change one of the bottom line conclusions of arm turn papers that achieving the Paris agreements aim to pursue efforts to limit warming of one and a half degrees c would clearly be safer than keeping global warming to two degrees c that's true irrespective of whether or not there are large-scale earth system tipping points at one and a half or two degrees c it is very clear that one and a half degrees c is safer than two degrees c and by extension two degrees is safer than two and a half degrees c that's because risks are escalating so this skeptical attitude doesn't mean i don't think that large-scale climate tipping points has maybe been identified aren't we're studying but that we should be cognizant of the tipping point metaphor and how it affects our communication um the other thing i don't think i think we actually have things that better fit the popular understanding of tipping points if we look at how earth system changes regardless of whether the physical changes are nonlinear or not affect human systems you do not need physical tipping points in order to get abrupt nonlinear changes in social systems that's why you know the term tipping point originates in the sociological literature as i said about you know when a a neighborhood in the 19 you know tips from being majority minority uh from being majority majority to majority majority understanding the sort of social tipping point behavior the nonlinear response to the human system the climate forcing strikes me as an area that is perhaps at least of urgent research because of its uh that's implications for policy has physical tipping points um the area of compound extremes right so we have different types of extremes for hurricane plus heat waves that occur together or extremes that occur over an usually broad area for instance a drought affecting multiple bare basket regions i think these type possibly have the potential to lead to tipping points in social systems even though they do not necessarily have to involve earth system tipping points we need only look at the example of the pandemic where we have extreme epidemiological conditions across a very broad area um to see the point that you don't necessarily need a physical tipping point to have social tipping points now social tipping minds can be bad for instance we can tip from a state in which we have a healthy and functioning democratic governance to one in which we have paralyzed governance that can collapse into autocracy or they could be beneficial as from a state of paralyzed climate governance to one of active governance and if you go back in the um political science literature in the 1970s the concept of punctuated equilibrium has been applied to environmental uh governance uh well before the concept of climate tipping points um so i would argue that yes these large scale earth system tipping points are important to understand because we want to understand the earth system but if the priority is to inform mitigation and adaptation i think the focus actually needs to be a better understanding the relationships between climate changes linear or non-linear um in human system responses and how those human system responses interact thanks thank you um it's you've generated many questions that i have but there are also many on slido so i'm going to go there thank you so much for that provocative presentation all right everybody so it's it's time to think about the slido of questions we have about 30 minutes to to present some of those questions and have the different speakers respond to them you can go look at them you can take part in the upvoting the one that has there are three or four right now with four votes i'll start with one of them i'll read it and then one of the three speakers is welcome to respond and if time permits then um try to keep the responses somewhat short so we can give the other um presenters time to respond as well if they want to weigh in so beginning with the first currently is it more feasible to work towards preventing a negative tipping point or to work towards a positive tipping point one of you like to take that question i can chip in Dorothy um because i've also been devoting an increasing amount of energy to what the questioner calls studying the positive tipping points um in recent years by which i would mean there are self reinforcing self propelling changes in for example the transition to renewable energy electrification of transport and so forth and um and and the more we get behind those changes the faster they can unfold in some simple sense so i think the point there is that positive tipping points framing gives us back some sense of agency in the face of uh what is undoubtedly an otherwise daunting situation vis-a-vis climate change whether linear or non-linear um so that doesn't direct the answer the question uh in its framing of feasibility um but i think it is from in practical terms um we have more power as individuals uh and as pension holders and and so on and so forth um to be part of affecting positive tipping points than we would feel we have the agency to stop the bad tipping points although i do believe there's an opportunity space to think about um non-linear adaptation strategies in other words even if we don't think we could stop bad climate tipping points entirely we could think constructively about whether we can do some transformative adaptation and that might also be empowering thanks thank you so so if i could add on um i mean i think this is something where i think tim and i uh agree i am much more comfortable very clearly with the term tipping points when we're talking about social systems uh and positive tipping points i think as the way tim was talking about the way i talk about it are tipping points in social system that lead to better environmental governance so i think a simple answer is uh if the negative tipping points you're talking about are largely these large scale earth system changes that become more likely uh you know the more you create risk uh that seems like not only like the question feasible to working towards preventing the negative tipping with the way you do that is through through catalyzing positive tipping points that lead to temperature stability so these i think these are actually it's not a it's not a dichotomous it's uh you know the one is a prerequisite for the other thank you um jeff do you want to say anything move on right i'll move on then to the next question how important is the study of past global warming events such as the um helicine easing or more maximum in understanding the risk of future tipping points so for those who don't know what that is that was 55 or 56 million years ago it was there was a large release of carbon to the atmosphere the source of which is still somewhat debated but it caused a persistent global warming of around five degrees centigrade stepped over an interval of tens of thousands of years um but then persisting for at least 100 thousand years and it's and it's in turn linked to well both some extinctions but also the interesting the the origination of some major mammal lineages so is it useful to study past events yes for sure if it gives us a sense of um the potential for feedback and nonlinear and sometimes tipping dynamics in the earth system but we've also always got to carefully caution that against the fact that the current background climate state of the holocene the last 10 000 years is a radically different one to the paleocene background climate state upon which this large carbon injection happened so as scientists we just always we learn something always by studying past nonlinearity in the earth system but we just have to exercise good scientific care in which insights we carry across to the present and the key ones are perhaps just the core process understanding that we might gain and perhaps in that case the very salutary lesson that just as our theory would predict if you hit with global carbon dioxide level hard um it's going to take hundreds and thousands of years for natural quote unquote processes to bring it back down again thank you sorry okay i mean the other thing again and this is where um yeah that the other and critical use of the paleo record right even under though the timescales are different is that it is the only source of actual past natural experiments we have for testing the models we are using to project future change right so uh you know if we can't explain you know and this is ptm as part of this but also that the even equilibrium state or more stable states of the climate system and we can't explain them with our earth system models right that suggests we're missing something in our earth system models and you know you don't even need necessarily the tipping point element to that i think that's important that the ptm is really useful because it gives us sort of a natural experiment of the response to something that on a geological timescale anyways it's a pulse of carbon dioxide even if you know how fast that pulse came is still um you know contentious uh right so it gives us something about about geological carbon cycling demand but the more basic thing well we need natural experiments to know you know to know what happens uh if you take the climate system out of its current state and that's something only the paleo record can provide us thank you and as a reminder for everybody we will be discussing questions until 1140 so we have a bit of time left to do that let me move on to another question are some societal tipping points equally rapid to some earth system tipping points and the list included here is population growth resource use land use change toxins and species extinction i feel like i should have a chance um you know just from we move on a different scale uh the the concept of geological time i think has always been really difficult to to get across uh on the policy level um you know just going back to it what bob was saying yeah the term tipping point may be the the only recognizable phrase to a lot of the public and policymakers in this entire three days and i think that's part of the challenge from from the on the on the policy implementation perspective uh we're still uh the primary message if you're talking to a policymaker is this is the difference between climate and weather uh so when you're on that level communication uh we're we're looking at decisions that that are being made now that are affecting us over anywhere from the next few months to uh the next couple of decades so i don't really think you can compare the time scales the challenges how we tend to perceive risk and make decisions we focus on what is right in front of us and for a policymaker decision or even just general human perception long term might mean 10 years so i i think they are worlds apart any other comments if i can yeah so building on what jeff says i should as a general rule most societal tipping processes are faster than most first system tipping processes there's some timescale overlap where there are some slower societal tipping people who are specialists and tip and the tipping of technologies coupled to society will sometimes argue that there's a half century timescale at least historically sometimes in major technology transitions although others like the switch from horse drawn carriages to automobiles was more like a decade but there are some climate tipping points that are plausible and could unfold quite quickly i highlighted the collapse of what's called deep convection the sinking of waters in the laprador sea because of the coupling that has to the climate in europe to the sea level on the northeast seaboard of the u.s to west africa in models that tipping can unfold within a decade it can happen it happens in several climate models at low levels of warming below two degrees sea above pre-industrial so i think that one warrants further research shall we say to further assess its likelihood because a decade of that decade of scale tipping would pose a bunch of novel adaptation challenges and that speaks back to a point bob was making saying i know why why bother about tipping points does it have any material difference to mitigation or adaptation policy when it does have a material difference to adaptation policy if a tipping point means a change in the spatial pattern of climate climate variability or change so if it does something it's distinct from what the linear change would do and that example is a classic case in point where it has a quite distinctly pattern change which wouldn't give you what you're otherwise expecting but it's uh you know i've peeled out one example there and um it's a subset of the things that i put that are on those maps where this is person and where you have a both of potentially fast tipping system and it poses novel governance challenges i mean i think i would echo white people and by and large societal change is going to be faster than you know certainly than ocean or a sea change generally than atmospheric changes that at least are capable of emerging above the noise of natural variability ecological changes probably you know sort of somewhat intermediate between how fast societal change can happen and sort of you know large large scale changes but you know the faster ones in general are going to be societal ecological or perhaps atmospheric um and uh you know i think it's uh you know i think it's always you know if we're we're serious about doing transdisciplinary research or anything it is helpful to start and mind well what are what are the specific decisions uh you know we we would we would be making and and do these matter and i you know i i think i think that the the big question of okay can just you know even you know the the amok study times looking at stuff that that was looking at stuff over over many decades um you know that i think that the more urgent challenge of well how is society going to respond to more frequent and extensive compound extremes over the next decade or two right that that that's got to be up at you know you perhaps even higher priority in that discussion and uh you know in the course of doing that you're probably going to get some answers about adaptation that also turn out to be relevant you know in the case you do have you know the massive aridity um we showed for the amok thank you the next question regarding physical tipping points how complete do you think our understanding of tipping points is 50 90 or 100 percent is the geographic concentration of them in for example the north atlantic related to sampling bias or fundamental earth science or both i'd be happy if we were at 50 percent understanding on this i wouldn't want to claim any higher i think there are probably quite some unknown unknowns out there as well as plenty of work to do on sort of the what got called the known unknowns as for whether that um north atlantic clustering is some is i think it's a mixture of a real earth system dynamics and a sort of bias of researchers and study the real earth system dynamics element is just because that if you think about the overall overturning circulation of the ocean uh the kind of formation of deep waters is fundamentally uh in the northern atlantic region although there is some in the southern ocean as well um but yeah i think the point is well taken that and i think the message from the question is if we believe that this is one part of a one important part of a more complete risk assessment as a climate problem so i'm not claiming that tipping point's the only important thing just to answer bob i'm just saying i think they're an important part of a sound risk assessment as a climate problem i would still argue that they are grossly under-researched compared to some other important parts of the risk space and the question alludes to that well i don't think we've taken and i said it in my talk i don't think we've taken a rounded overview we certainly haven't researched the potential impacts of the even the events that we do recognize let alone the ones we haven't thought of um very thoroughly and we certainly haven't been making systematically at who is most vulnerable to specific tipping point scenarios which would also be essential in a rounded risk assessment so plenty of work to do folks but of course we all have finite like money intellectual resource so my my for me the guiding light is you've got to as a community we deploy that resource to give the most effective in this context um risk assessment and risk management advice um to society and decision makers okay two two other thoughts so one uh you know low likelihood high impact outcomes are often treated as a closely related topic to tipping points that that i think that's fair to characterize our current understanding the way that doesn't inherently have to be the case it just happens that uh you know most a lot of the typically called tipping points are currently low likelihood high impact or or what ipcc uses low likelihood as a synonym for unknown likelihood in that context um so i got some more to note um the other thing you're just thinking about has tim was talking you know if you look across climate models right now um in terms of how sensitive they are to climate a lot of that is controlled not by the north Atlantic but by cloudiness in the southern ocean um i haven't seen much thinking about and maybe tim has seen it but thinking about tipping points and sort of southern ocean cloudiness but just based on the significance of southern ocean cloudiness for the differences we see among climate models uh it certainly seems to me quite reasonable to look about whether you could look at whether there are mechanisms that could lead to rapid changes and that there has been some work at sort of equity i think equatorial cloudiness and the impacts of that on climate sensitivity but that's not like controls the differences among gcm significantly so any time would be you know it seems like important to know whether that behavior is possible there i totally agree just to note we we looked at what was already out there in that armstrong okay at all paper it didn't make it as it as you saw on to the final maps but i think spot on absolutely and i wonder if the person who asked the question venjamin if you um think you've gotten the answer about the 59 year 100 um i gather less than 50 probably is that correct i thought i'd give benjamin a moment to weigh in here if you would like to i really appreciated those responses i yeah i don't think there's that answer but i appreciated the reflections from the panelists thanks y'all yes you're welcome and i agree um it's it's really good to hear the different reflections and perspectives all right let's go on to the next question we still have 10 minutes for this first session from gabrielle are our modeling tools and quantitative understanding of physical processes involved in tipping points and social impacts sufficient to assess risks associated with transient high overshoot scenarios and what's needed most urgently we we can always do better um with the modeling in real um but the modeling is still useful all models are wrong so we're useful um we've got a lot of work to do for sure on this issue of getting down to the scale of social tipping points and social impacts via ecological and resource system non-linearities or linearities um i would say what's needed most urgently is some effort on just mapping out um both the impacts of different recognized plausible tipping scenarios but also the vulnerability or exposure of people and if you agree with me also other living things and ecosystems um they're a differential exposure to these scenarios so that then we can at least attempt to risk assessment that may sound a little biased to the big stuff but i meant it in a broad sense as well and then i think a wide number of people would agree we ought to have a better capacity to look at cascading and interacting risks across systems my personal view is we have some of the pieces of the puzzle there but we've no group has been properly incentivized to put together the tools we have to build anything like a quantitative framework to consider cascading risk all we do is a lot of horizon scanning useful qualitative stuff but i don't really believe we could do better so um i'm sorry jeff jeff you you came up with me do you want to weigh in here first i've been uh go go ahead i'll i'll bring up the bring up the rear okay um so i mean i think where we we as ten point out there's very little on social impacts of physical tipping points um so it'll get very little there the other thing you know if you looked at the the plot uh temp showed of of when we slept right that you can see like most of them had at least one degree wide you know there's large scale ones have at least one degree wide uncertainty interval so uh could be possibly understand the risks associated with transient high overshoot scenarios given you know given that those uncertainties uh probably not do we you know do we have a pathway to narrow those uncertainties significantly before we have a transient high overshoot scenario maybe maybe not um i think it's an area where the storyline approach uh that the ar6 started using right where we you know rather than saying well can we you know how well precisely can we predict where these thresholds are where we start thinking you know working through the implications of crossing them rather than focusing on uh you know is it you know if we if we go up you know go from 125 up to 1.9 and then come down again how likely it would be caught to cross them versus you know stabilizing it too um i think trying to under you know work through the storyline seemed to me perhaps even more urgent uh and then then trying to narrow those uncertainties because i think i think there's been less done there and so i think the potential for progress is perhaps faster than you know trying to get you know get really precise estimates of you know 1.7 versus 1.5 um yeah i'll echo what bob said about there there really isn't much in the way of in my opinion meaningful modeling on the on the social impacts um you know to extend tim's uh george bock use of the george box quote it's a yeah model's wrong some are useful are is the wrong part can you live with the wrong part so that the useful part is sufficient and we just don't have much there this may only be a little bit of what the question was was leaning towards but if you look at how we're using that towards um assessing designing and assessing adaptation most of what we've done in terms of both modeling and and standard development or even benchmarking is on the built environment where it's a lot easier to do quantitative analysis and come up with meaningful standards for the non-built environment social and economic not only is there not much there but i think that uh qualitative analysis is probably more meaningful but we've yet to agree on what is what is a useful set of standards uh in part be you know the whole the whole resilience buzzword uh we still have trouble determining what a what a useful baseline is today let alone uh when things get worse jeff i wonder if you can comment um on the heat dome example you gave in reference to this question and so many people being impacted by that in that one case you mentioned well i think it's going to be less unique heading forward i mean you know for ours it was it was record breaking for the pacific northwest uh and this past summer um you know california had a horrific you know extended uh worse heat dome um you know we saw in a year in the northwest uh a series of effects the large windstorm in september 2020 that led to the northwest blowing up in fire a lot of uh effect on uh trees and forest ecosystems we had a major ice storm that knocked out power to several hundred thousand people at the same time as going on in texas and mississippi um and killed a lot of trees which became really apparent in june when we had hot weather about two months before we usually do which means two more days two more hours of daylight which killed more trees uh and the the the tree cover uh you really have an essential part of the forest ecosystem that we've come to rely on here has been not just damaged but likely changing maybe a bigger issue if you look nationally and and maybe even globally most of us power grid is really geared towards primary energy use in the winter for warming and we're seeing a shift to uh predominant use in the summer for cooling and that's not just a question of what time of the year we're doing it those are different systems different infrastructure and we're just not well designed for that and that is only going to be exacerbated as we go forward um i think there's greater recognition that heat is a major issue in parts of the country it didn't used to be uh when i moved to oregon 20 years ago from texas it was oh we don't get heat here it's like yep that's why you need to deal with it i think more of the country is coming to grips with that but that's still going to be a major problem going forward we're just our infrastructures and set up for that our social support systems aren't set up for that so um it's the what we saw in 2021 isn't going to be a one-off thank you very much for that jeff we have time for one more question so going over to slide oh from brian the initial conceptual model depicts moving from one stable point to another is it possible that we tip into something that is unstable well ultimately there's always going to be somewhere where a system settles down but the question could be interpreted as um could we have what um what might be described as a global tipping point um towards a very different climate state um there have been clearly suggestions in the literature that that might be a possibility that's hard to rule out including the idea that we would tip back into a warm house or a hot house climate state like we saw at different times millions of years ago in the cenozoic personally i'm of the view that the that we're more likely to be heading into what i think of as the wet house where the runaway or the very difficult change to stop is meltdown of major ice sheets raising sea levels by more than 10 meters in the long run and reshaping the coastlines of the world just to re-emphasize that doesn't unfold necessarily quickly the time scale depends on by how much we warm above the tipping point for each major ice sheet because the rate at which ice melts depends on the amount of heat energy you put in but yeah i think we could it's not we can't what i would say is we can't rule out that uh yet i think credibly that um that you could set a chain of consequences going that take a very very long time before they settle down and that time scale depends on the the dynamics of the system and the ice and the sea level would be the slowest bit to settle down i should emphasize that none of the IPCC models as yet get thankfully get a true runaway global warming or a hot house state but as bob hinted there are models which show really strong cloud feedbacks that give a much larger temperature response than the the mean expectation and i so i definitely think on both fronts there's room for more research if i need to try to rule out the possibility of a sort of global tipping change thank you it is the end of this session i would like to thank all three presenters and all of you participating and submitting questions i'm sorry we couldn't get to all the questions perhaps they'll come up again in another session we have a break now until 11 um until 12 15 and at that time we'll return from the break for the next session on historical analysis of past biogeophysical and social tipping points so thank you all for participating sir in the school sustainability at arizona state university um it gives me a great pleasure to introduce our first session after this uh wonderful overview that we just had for the next hour uh going from 1215 to eastern to 115 uh we will be talking about historical analysis of past biogeophysical and social tipping points we have four speakers we'll start with uh dr victor bravkin professor at the university of homberg in germany and the mox plant institute for meteorology following that uh we i'll i'll introduce the others um we'll have three speakers and then uh with 10 minute talks in five minutes for questions again your your your questions can be put into the slido and we'll call those out so we'll have five minutes for questions and then we'll use the time at the end for an extended period of q and a for for our speakers without further ado uh let me turn it over to victor bravkin next we'll turn our attention to dr elin noy chair in the economics of disasters and climate change at victoria university of wellington dr noy yes um good morning evening whatever it is in your time in the world i assume you can hear me yes um so i think maybe maybe nicely as we had in the previous session we had team who emphasized the earth system and bob who emphasized um the social aspect or the social tipping points i'm going to do the same thing uh in this session um and i want to um talk a little bit about the sort of the the economist view of of tipping points next slide please so i'm first i want to describe to you a little study that we published um or we circulated last year and which but the basic argument there was that we should look at extreme weather events as a as a significant uh already significant impact of climate change um on human society and specifically on the economy so what we did is we took the um the existing attribution studies that have um calculated fractions of attributable risk so we collected about 250 attribution studies that have been um um conducted in various places around the world for various extreme weather events we matched them with the economic um costs of these events as these were available if we could find uh a match and then once we um extrapolated um from that to other types of um or sorry to other uh extreme weather events for which we didn't have the um attribution study or the economic cost then we sort of achieved that some some rough estimate of the current cost of climate change in terms of extreme weather events next slide please um so just to um sort of show you what we have done is we looked at um fractions of attributable risks around the world and um for example we you you probably already know that heat waves have been becoming much more likely because of climate change so about um on average 77 percent more likely um floods depending on the regions uh on average floods have become more likely but some regions um it floods have become less likely cold cold events have become of course less likely um around the world but what we do here is we match those fractions of attributable risk to economic costs um and then we we argue in the next slide next slide um where we we can um estimate the um the damage from extreme weather events associated with climate change uh currently on the on the world economy so you can see that it ranges from year to year in the past 20 years but in years in which it was high it was uh almost one percent of global GDP so it's a very very large uh number and indeed uh next slide please when you look at the actual number then on average in the past 20 years um the average cost of extreme weather events associated with climate change so the direct damage associated with um the part of extreme weather events that is associated with climate change we evaluate that to be about a hundred and uh well 150 um billion US dollar per year which as you can imagine is a very large number but it's also I think more importantly it's much larger than our current estimates in the integrated assessment models of the the current cost of of climate change so what I would I'm trying to argue with this in this paper is that the uh extreme weather events so these uh as Bob called them um low likelihood high impact events um that are already happening um because of climate change meaning climate change is increasing their intensity and or frequency um these are very impactful in the economy um already so that's my first um argument um next slide please so if we look at those extreme weather events what they do um is they cause some damage that's damage that damage can be measured in mortality or in asset damage as was in the as was done in the previous slide but then that leads to declines in economic activity with potentially um longer-term losses to well-being of the individuals who live or the communities who are affected by those extreme weather events and that's where the tipping points start to to be a concern next slide please so if we look at what can happen after an event from an economic perspective we can sort of think of several scenarios what will happen after a disaster event there might be a recovery from the disaster event in some very optimistic views there might even be a sort of a economic activity that is um economic activity will benefit from from the disaster event but if we look at the historical record then next slide please the most likely outcomes are one of these two okay uh one is where there is eventually a recovery back to um trend uh to this counterfactual trend so what so recovery to what would have happened anyway if the disaster hasn't um happened that's on the right uh or potentially there is permanently lower growth path okay the assumption here is that there's a just just a horizontal shift downward but then growth um resumes that's not necessarily the case and that's where the concern I think is of um tipping point so the way I interpret the the term tipping point it's more to use Bob's terminology from the previous session it's it's more of a Malcolm Gladwell maybe use of the term is an extreme event that tips the economy into a different direction and I'm going to give you an example next slide please this is from a paper we've done at almost a decade ago where we looked in in several countries that are affected by extreme events in this case it's actually an earthquake not a not a weather events but the argument holds for other types of events as well uh Iran is hit by an earthquake in 1978 and then the economy collapses okay so the economy collapses starting in at the end of 1978 so 1979 is already declining economic activity and these are the um the sort of the the circle circle the line of circles um and where the line of triangles is where the economy would have been had that event not happened now of course what happened in in Iran is 1978 there was an earthquake but that started the cascade of um dynamics which led uh less than a year later to the Islamic Revolution and two years later to the Iran-Iraq war and a massive decline in economic activity so at least in this assessment income per capita in Iran 10 years later are about a third of what they would have been had this event not happened okay so that that for me is the interpretation of a of a of a tipping point the insight next slide please the insight that that this is possible that an extreme event can trigger an institutional change or in this case the the Islamic Revolution in the case I'm quoting here this is actually a quote from Voltaire's Candid not sure if you're familiar but Candid was well is a a short novel written by Voltaire in the 18th century Candid is maybe the the forest gump of the 18th century so he's sort of is everywhere that something important happens in Europe at the time um and he's in in Lisbon when there is the Lisbon is experiencing a triple disaster a fire earthquake and a tsunami and in 1755 and he observes how this event triggers all these institutional changes um in in the political system in Lisbon that have all these consequences to to to the to economic activity in some cases beneficial in some other cases not so much so the the point I would like to emphasize is that the for this crowd and for this for this workshop is that the way I see tipping points is those events that can tip the political system that can pick can tip the social system into a trajectory that is potentially very very abrupt change and potentially quite catastrophic there are other examples of this kind of of a shift next slide please and here I just have two three examples sort of going from the local to the international since there was a question about international in the in the last slide in the in the last with the victors after victor's talk so one one example is a paper that was done by Richard Hornbeck on the dust bowl in the united states that occurred in the 1930s so he he showed that after the dust bowl counties that experience the dust bowl most intensely experience a decline in population and in incomes and in the value of land that persisted for at least 50 years um later so that kind of persistence in the impact even though the dust bowl itself so the loss of top top soil that was the main sort of trigger of the dust bowl um lasted for maybe only a decade the economic consequences of that event lasted much much much longer than that and potentially till today we another example is from Myanmar or Burma which had tropical cyclone Nargis in 2008 that led to a whole cascade of events in the country that eventually led to a beneficial change in the regime so eventually the the general's left and and the the democracy was restored there were elections Ong San Suu Kyi came back into power but of course we know that that has been reversed later but the point is that that event triggered a set of political changes that in some cases can be beneficial and we have cases in which it was beneficial the Meiji restoration in in Japan for example could be such a case but in in other cases it's more mixed like the case in Myanmar or it could be very adverse the more sort of international example is of course the drought in the Levant in the 2000s that is at least a contributing factor to the civil civil war in Syria the civil war in Syria led led to a migration crisis that affected Europe and resulted in all kinds of adverse consequences in Europe through which we are still experiencing today and will probably be experiencing for decades to come so I think with that I will I will end but I do I do want to emphasize one thing and that is that these kind of changes don't don't necessarily revert back or sort of don't we don't end up necessarily in a in a in a new equilibrium which is which is settled so I think potentially social systems don't have the the kind of maybe characteristics as as described by my colleagues the earth scientists in which the perturbed system eventually settles down into a new equilibrium that's not necessarily the case for social systems wonderful thank you dr. Noi we have time for maybe just one question let's start with with this one from Jesse Abrams how do you make a case for a causal link between the 1978 Iranian earthquake and the 1979 revolution yeah so um that case was made by historians not by me but the case was that the the efforts for response and recovery in the aftermath of the earthquake were completely botched by the by the ruling Shah by the ruling regime while Islamic organizations were very efficient on the ground in in assisting those people who are affected by the by the earthquake and both received a lot of popular support because of their activities in the aftermath of the earthquake and also built up in sort of in learning by doing dynamics also built up the organizational capacity within themselves to organize and and eventually overthrow the the regime so there is there is an argument now whether you know the regime would there have been a revolution if the earthquake hadn't occurred of course we have no idea but but there is clearly a contributing factor to what happened during the earthquake to what happened less than a year later in terms of the revolution that gets into lots of interesting questions about causal clusters and how we have very uh there are very few direct causal links in some of these cases in social systems let's turn it to our next speaker i hope we can come back to some of these questions if we have time at the end our third speaker is dr benjamin cook a research physical scientist at the national aeronautics and space administration goddard institute for space studies without further ado dr cook oh great thank you very much uh next slide um so yeah sorry yeah so the the dustball drought was arguably the single worst disaster in the history of the united states um fundamentally this is a very severe drought that affected much of the central plains united states uh caused widespread crop failures land abandonment human migration within the country um and of course directly caused or contributed to the kind of occurrence of but at the time were were fairly unprecedented uh you know dust storms you know captured in some of the iconic uh photographs of of the time period uh now the interesting thing though is that the central plains is a drought prone location in the united states before there were severe droughts before the dustball there were severe droughts after the dustball um but no other drought in the central plains uh at least in the last 400 years uh really ever had the same level of land degradation crop failure wind erosion or or dust storm activity um and so you know what i'm gonna try to make the case for today is the fact that the dustball itself was this kind of unique combination of bad luck and bad choices you know all of the intersection of the physical climate system um the ecology of the region and various choices that people made um and so you know to really understand the dustball you know we need to kind of build up that case and understand all of those contributing factors um you know to start oh next slide please we really need to go back to the 1900s so what you're looking at here are two uh maps of crop area from 1850 and from 1930 1930 being right before the dustball really began to get going um and basically until the late 19 until the late 1800s uh the vast majority of agriculture in the united states was in the eastern us kind of east of the east of the mississippi um after the civil war in the mid 1800s uh the u.s government undertook a campaign of basically genocide and displacement of the native peoples over the central united states which opened up a lot of land for settlement of of citizens and you know over the latter part of the 1800s the what we see is this large-scale shift of agriculture into the central plains region and you can kind of see that there in the in the map for for 1930 now all this agriculture was shifting from a relatively mesic wet region in the eastern united states to a much drier region in the central plains which is you get much less precipitation and so as a consequence uh they had to adapt various um cropping practices to basically preserve water and to draw water up from from depth uh next slide please uh the fundamental or first kind of method that was largely adopted and then eventually kind of modified was the Campbell method where basically you have subsurface packing where you really compact the soil that allows for the draw of soil moisture deeper in the soil profile up to the surface and also a creation of loose what's called soil mulch a kind of loose less dense layer of soil um up near the top to basically reduce evaporation uh next slide um with the advent of mechanization uh the number one tool being used in the 1920s for plowing these lands in the central plains was the one-way disc cloud which is a very efficient way to kind of plow these uh these fields and generate lots of this mulch to reduce evaporation uh but as you can probably figure out if you're creating all this loose soil mulch you're creating a situation that is potentially very vulnerable to wind erosion and loss of the soil right so you're kind of you know adopting cropping practices that's you know priming um this area for uh for wind erosion uh next slide um and then the final thing that's worth noting is that we were you know farmers were replacing all the native drought adapted deep rooted crops uh or deep rooted vegetation in the central plains uh natural grasses shown in the blue circle right there with uh much more shallowly rooted much more drought sensitive uh crops like wheat and in some cases in some cases corn or maize all right so we're kind of replacing the native ecosystems with much more kind of erosion and and drought vulnerable crops uh next slide uh now this all kind of really started kick started in the 1890s and for a while it wasn't really a problem um and the reason for that is because the early part the late part of the 1800s and the early part of the 20th century was an extremely wet period in the central plains and across most of western north america uh oftentimes referred to as the early 20th century pluvial event and so uh because it was wet enough all these kind of non-ideal practices didn't really result in any real negative consequences of this agriculture uh because you had enough water to kind of sustain the agriculture and and the crops that were that were being grown at the time next slide um unfortunately with a shift in ocean patterns which is a typical driver of drought in western north america in the 1930s you shifted into this dust bowl drought event um and that kind of kick started off uh kind of cascade of events uh that led to the whole kind of dust bowl itself uh next slide um this is what that drought looked like so the kind of decadal average precipitation on the left um you can see this kind of bullseye over the central plains where most of that agriculture moved and during this event there were some really standout years as well that really kind of you know uh you know highlighted the intensity so 1934 for example was a was a very kind of you know classic really severe drought year uh next slide please okay so with the drought emerging uh we saw large-scale crop failures across the western united across the central plains region uh this coincided with the great depression so an economic depression farmers really couldn't afford to replant their fields and with this large-scale um failure in fact you know in a relative sense the the largest scale crop failure in the history of the united states at least in the 1900s you had a bunch of farmers effectively abandon their lands with this land abandonments they left these fields just be vegetated and uh because things were dry and because the central plains is windy it started to generate many of these dust storm events that you know show up in those iconic photographs uh next slide uh you know here's one record of dust storms from dodge city canvas coming from the 1920s up through the present day and again you can see the big spike there in the late 1930s associated with uh with the drought at the time and you can see that you know other periods you have these dust storms but nothing anywhere near the same kind of level uh next slide oh okay i don't know what uh okay uh next slide all right yeah i don't know what i figured to show up but uh you know these were very big dust storm events so these events spread dust over hundreds sometimes even thousands of kilometers and it really did affect both the southern plains and the northern plains as you can kind of see here in this report of dusty days across the central united states next slide and then in the case of uh one particular day may 1934 you kind of had you know what is estimated about 12 million pounds of soil being eroded and deposited as far as the as the as the east coast in the united states so these are really big fundamentally uh large events next slide okay um 65 percent of the central plains was probably affected by 1934 about 80 percent of the southern plains by 1938 next slide you know this corresponded to about an average loss estimated about 400 tons of of soil per acre and a loss of enough of that nutrient-rich topsoil to actually reduce agricultural productivity by in some places 15 to 25 percent next slide okay um further there we believe anyway are shown that there is likely a feedback from all this dust and all this land degradation um effectively you're removing vegetation from the surface you're reducing you're reducing evaporation of water into the atmosphere you're adding these dust this dust these dust aerosols these dust particles into the atmosphere that um to stabilize the atmosphere and suppress precipitation uh next slide and so we were actually able to show that if you actually add these factors you add the land degradation if you add the dust aerosols into climate model simulations you can get a much better simulation of the dust bowl um of the dust bowl itself um so for example here on the left we have the observed precipitation anomaly from the dust bowl drought on the right we have a simulation that just use the ocean boundary conditions and if you go to the next slide we see that our simulation where we added in dust and these crop failures uh and we get a much better kind of match of the intensity and spatial extent of the of the dust bowl drought next slide okay so how did the dust bowl end well I would actually argue that on a certain level it's actually a representative of a sustainable recovery beyond a counterfactual trend um so uh at least a large scale um so when we got lucky in the 1940s was an incredibly wet decade there was a pluvial events that kind of ended the drought um but almost more importantly next slide um the 1930s led to a kind of reevaluation and uh and kind of involvement of various government's agencies to basically prevent this from happening again and so what you're seeing in the upper left hand there left hand side there is strip copying which is a management technique designed to reduce erosion on fields um the two tractors there or specifically types of tractors that effectively are designed to kind of mitigate erosion um there were large contributions from the federal government of both money and organization uh one of the most important things they did was organize farmers into soil conservation districts that basically provide kind of larger scale community incentives to put in these sorts of erosion control measures um next slide um and then the other thing that really kicked off especially after world war two was irrigation um we saw this kind of massive increase of irrigation that really tapped into the Ogallala aquifer or the High Plains aquifer of the region um and that provided a lot of water and provided a quite a bit of drought resilience to agriculture across the region um and in fact even today you know if you look at irrigated versus not irrigated crops over the central plains the irrigated crops are are are much less sensitive to drought compared to the compared to the non-irrigated crops uh next slide um so you know just to just to kind of summarize here you know I think that Dust Bowl is you know probably inappropriate sort of event to look at from a kind of tipping point perspective because it was a disaster that was really this kind of unique combination of both bad luck from a kind of physical system side of things and also poor or uninformed uh you know decisions and how to kind of manage the landscape and manage the event um you know I think what the record shows though is that because of these kind of interventions um and these kind of new management the lessons that are learned from the Dust Bowl such an event is is at least in the medium term or near term very unlikely to occur again at least uh at the same kind of scale as we saw during the 1930s. Thank you. Thank you Dr. Cook um so we have a couple questions here uh let's start with this question from from Gary Folk. What could trigger an event like the Dust Bowl in present times or or given what you just said perhaps um I can can uh expand on that a little bit and say are there other things that are on your radar screen uh that you could envision uh moving forward like this? I mean one concern that's you know a topic of quite a bit of a conversation over the central plains is the sustainability of the groundwater extraction so a lot of the high plains or Ogallala aquifer uh you know is effectively fossil groundwater Pleistocene water laid down during the Pleistocene um and so except for over certain areas there's there's not much kind of recharge of it so once it's gone you know it's it's pretty much gone at least on timescales that that people probably care about um so I think that's probably the the biggest kind of concern um that that I have um I mean what would it take to actually kick off another Dust Bowl? I I mean you kind of need a collapse of I think you know you need a drought and then you need a collapse of of many of the kind of new management techniques that we actually employ today. So building on what you just said there's a question from from Jesse Abrams would the shift to aquifer dependent irrigation represent an example of an ultimately maladaptive response adaptive in the short term but unsustainable long term? Yeah I mean that's a that's a that's a really good question I mean I mean certainly yeah they're they're you know the the high level of productivity over much of the central plains is very dependent now on on the Ogallala aquifer um if that were to dry up then those same practices and that same level of production would probably not be kind of tenable um but that doesn't mean that there aren't other opportunities to to change management or shift targets or even kind of shift you know crops. So I mean it's adaptive in the sense that it's working now but I guess if you want to keep the same level of agriculture and production in the future we're probably going to need to think a little bit more about other alternatives. And then we have a couple questions that are very similar. Christian says if Dust Bowl is unlikely to occur again in the U.S. what about other regions? Victor Rob can then expand it and said there's a large black soil belt in Eurasia. Could it be under a risk of Dust Bowl in the case of AMOC collapse and dryness presented by Tim? Yeah I think so but I think a lot of it depends upon the actual management practices right so one of the one of the key problems during the Dust Bowl was that all the practices were not designed to reduce erosion they were designed to increase moisture basically draw up moisture from going deeper in the soil and the problem is that you kind of have a trade-off there because of that mulch layer so if you're plowing for moisture then you're almost at least at the time you're kind of almost by definition plowing in a way that would potentially increase erosion you know but you know we're much smarter now we have better tools we have you know better techniques like strip cropping to you know mitigate wind erosion so there's no you know there's no reason that it has to happen but it requires a kind of thoughtful you know approach. Thanks Dr. Cook. So we were originally going to have Lee Kump a professor of geosciences at Penn State make some remarks in his place. Tim is going to make some remarks on his behalf Tim. Thanks Michael. Patricia are you able to share Lee's slides and I'll run through them. That's great so yeah now we're back onto the topic of the biology of physical tipping points but I think Lee wants to make a really fundamental point here about how tipping point dynamics come from the particular response of biology to environmental variables so next slide and he also wants to pay homage to Jim Lovelock who was also my scientific mentor and hero who died on his 103rd birthday last year. For me Lovelock was kind of the grandfather or father of system science and certainly is the reason why I started thinking about tipping points. Next slide. So Lovelock is famous or for some people infamous for originating the Gaia hypothesis which he developed with another scientific hero of mine the late Lynne Margulis if you press again and that hypothesis is really that life and the non-living parts of the planet coupled together are somehow involved in self-regulating or homiestatting the composition of the atmosphere and potentially aspects of the climate over geologic time scales. Stimulating for some controversial hypothesis but it isn't all about stability. Lovelock emphasised repeatedly in his books presented a pattern if you like of to interpret earth history as long intervals of stability interspersed with abrupt tipping point changes. Next slide. And he really got to the crux of something important which is that purely physical and chemical processes tend to have fairly monotonic or monotonous kind of kinetic rate laws and responses. Whether something is increasing with an environmental variable like temperature or decreasing it tends to be you know a monotonous function in one direction or the other. Whereas next slide in biology we see that physiological rate laws often or typically are characterised by kind of parabolic or hatch shape functional responses to environmental variables like for example temperature on the x-axis that could be a number of other things like carbon dioxide or oxygen or some critical metal or whatever. And this turns out to be really important for the feedback dynamics that can result if you have both this type of functional response of biology to an environmental variable and you also accept that sometimes biology like us humans affects environmental variables. So if we go to the next slide this kind of fundamental point is kind of well illustrated by Lovelock's Daisy World model which he came up with at Christmas 1981 to try and answer various criticisms of his guy hypothesis that it's somehow implied conscious foresight or purpose on the part of unconscious living things and that it was somehow odds with natural selection. Well Lovelock invented on an early personal computer a toy model of a parable if you like of a simplified planet inhabited by just two types of life black or white daisies nominally. The black ones absorb more sunlight than the bare surface the dust if you like or the soil and the white ones reflect more sunlight than the bare surface and that affects both their local environment and if they spread far enough their global environment. So if we go to the next slide yeah to capture these generic ideas Lovelock Jim put in a parabolic hat function response of daisies to temperature which would be typical for any plant you know there's an optimum temperature for growth there are some high or low temperature bounds outside of which it's pretty hard to grow but he also recognized that by virtue of their color or albedo the daisies affected the temperature and in the case of the white daisies the more shown here the more white daisies there are the colder the temperature is so we have that downward sloping straight line which for this case of white daisies only the straight line intersects the parabola in a couple of places and those are steady state solutions of the mathematical equations of the model but the one called P1 is a stable equilibrium of valley like in my earlier movie whereas P2 is an unstable steady state a hilltop and so that sets up already the possibility of interesting dynamics in the model if you click once more we'll see that for the black daisies the effect their effect on the environment is the opposite the more black daisies there are the more sunlight gets absorbed the hotter it gets again there are a couple of intersection points of the two functions which represent again stable states and the one sorry steady states but the one on the left is unstable and the one up at their top right is is a stable one and then if you click again we see that when the world is seeded with seeds of the black and white daisies when the sun is on the x axis is dialed up in its brightness so the luminosity at some point some black daisies will start to be able to grow but they will their population will explode exponentially through a tipping point of reinforcing feedback and the system will transition rapidly as it does from this unstable initial steady state over to the basin of attraction to the valley the stable steady state of the world dominated by black daisies then as you turn the sun up brighter over time because all stars on the main sequence then brighter over time like the sun eventually the white daisies take over and then at the very end you've only got white daisies left but you reach a tipping point where some white daisies start to die back that exposes a more dark soil surface which causes things to warm up with more kills even more white daisies and so on and we get a runaway tipping point that claps of life next slide so a kind of neat but totally hypothetical illustration of tipping points but in a paper in the mid 90s Jim and Lee worked together on um bringing this a bit close to the earth recognizing that um the plants on the land there are certain constraints of apotranspiration of high temperatures and so on that mean that their kind of growth response is curtailed that there's a sort of upper temperature limit for the p the plants but for algae in the ocean the situation is more acute because when you get above about 12 degrees centigrade the surface of the ocean stratifies from the bulk of the ocean below and that seriously restricts the nutrient supply to the algae the a and s diagram so that's a sort of earth informed representation of how this these hat functions look for in broad terms for algae and plants on on our planet and then if you accept that both algae and plants have some effect on the climate you get again a couple of feedback system and the possibility of tipping points so the plants for example we well know amplify rock weathering which is a long-term removal process for carbon dioxide from the atmosphere and that profoundly cools the planet but equally the algae and many of them uh calcareously shelled to an integral part of carbon removal from the atmosphere as well so then both in simple terms can have a have a significant cooling effect on the climate so if we go to the next slide and we've kind of represented those parabolic responses and we've represented the cooling effects of both well then if we dial the brightness of the sun up or put some other forcing to higher temperature on the system in this toy model again you can get a tipping point the first tipping point is going to be for the algae that are you know when it gets above 12 degrees C and the surface ocean starts to stratify um they their coverage can potentially collapse and their cooling effect with it and the temperature would then kick up somewhat in the model as to what their cooling effect is well i mentioned one possibility but i think in the model they wrote about this in reference to the fact that many algae make a compound called dimethyl sulfide the oxidation products of which sulfuric acid essentially are the major cloud condensation nuclei in the pristine atmosphere in the absence of humans and by adding condensation nuclei to clouds you make them brighter because you spread the same water over many tinier droplets and that looks whiter so that's probably the key cooling effect here of the algae that breaks down if you heat the system past this tipping point where the ocean surface would stratify of course this is a simplified we would say zero dimensional model but it carries i think a conceptual lesson in where tipping points can come from when you have biology coupled through chemistry and physics to climate next slide uh just one minute yeah and these these finishing up here by making the point that if we look in earth history there's there's a key episode of kind of breakdown of regulation in the climate system the great dying event 252 million years ago at the end of the end where there i think his argument would be that the best candidate is that we know there was a large scale loss of forests at this extinction event that would have removed the cooling effect of those forests and rock weathering and it appears to have knocked the earth system into a hotter state of the early triassic it took at least five or nearly 10 million years for the forest to come back cool things down again so they could sustain themselves next slide and i think it's the last slide so if you just click through patricia um to summarize Lee's argument is that life both affects and is affected by the environment temperature in this case hence life is part of global scale regulation in the climate oxygen etc the rate laws matter the fox sign of feedback can change above and below a peak in one of these hat functions and and that is the basis or key fundamental basis for tipping points maybe one more click see if there's something there yeah and maybe the end permeate dying is is a classic example of this happening in earth history hope i've done some justice there that's the end of the slides from me wonderful thanks tim um we just have time for one quick question maybe we can start with this question considering the biosphere as a continuum uh how collapse or reaching tipping point at one node at one location at one point in time can produce ripple effects in different nodes how can these negative impacts be dampened great question because yeah i showed this very idealized world from lee without that spatial structure and many people would argue you when you have spatial heterogeneity that can dampen out or reduce the the danger of large-scale tipping dynamics but you're right to point out that also it can introduce the problem my ecology is network that tipping can spread all i can say generally there is our empirical evidence there are cases where indeed it spreads in a pathological way where the larger scale feedback kind of amplifies and tipping cascades out from source locations but that's a that has to be a pretty rare turn of events there is also situations and famously one of them is pattern vegetation in drylands where although there's locally very strongly amplifying feedbacks the patterns arise because at a larger scale there are tend to be damping feedbacks and you know and some people are perhaps rightly arguing in the literature that that those the resulting sort of spatial patterning tipping points of vegetation are a kind of tipping point that actually helps the the dryland vegetation maintain itself down to otherwise drier conditions than it would have done so in broad terms yes you highlight a possible risk but we have to look case by case and actually there are some there are also some positive cases where even the tipping dynamics connect to possibly keep resilience in the case of the dryland vegetation thanks Tim thank you to all all four of our speakers in this session this concludes session one we're now going to turn our attention to a breakout activity so the way this is work we have 30 minutes for this breakout the breakout is going to be in three parallel rooms one on large longer scale perspectives one on cascading risks from the last thousand years and the third on cascading risks from the last century the breakout room capacity is limited so we've randomly assigned breakout groups due to the popularity of the topics and technical kick capacities that we have we've had to limit the number of individuals for breakout we do value everyone's opinion and input and want to hear from you from as many of you as possible for those not assigned to a breakout room please share your thoughts and topics via the Slido ideas tab the the questions to discuss have been posted so feel free to drop your input into Slido and respond to other thoughts moderators are going to be taking notes so we have 30 minutes for this the last five minutes will be used for for moderators to synthesize three key bullet points and post to a google doc that will then bring back together at 145 eastern to report out and close the session for today so for the next 30 minutes we'll be in breakout rooms thanks today's session of course tomorrow we'll be back at 10 a.m eastern time to turn our attention to regional perspectives on climate tipping points and cascading impacts among other things in this last 15 minutes we wanted to have someone from each of the breakouts report back maybe we take a minute to gather our thoughts before doing that and then once we do Simon do you have you or someone from your group can you kick off the first the first report back yes thanks Mike and hi everyone if you weren't in my group I'm Simon Deets professor at London School of Economics and a member of the planning committee for this workshop yeah so we so Mike we gave ourselves about 38 seconds to summarize our session so I've been busy trying to cobble together three bullet points as instructed so we our group was tasked with discussing the large scale or deep time perspective so I've picked out three points and I would after I've given them you know and to invite Tim to jump in and say if you if I've missed anything firstly we talked about how the large scale perspective leads us to wonder about the stability of the earth system when subject to forcing of various sorts and we discussed how there are many key research questions still out there in terms of how stable the earth system is the coupled natural physical system secondly I think what was interesting is how often the social aspect came up in our discussion and so I guess a big question is getting a proper sharp sense of the relevance of the deep time perspective for social systems and social science questions that is not to say that it is irrelevant certainly not but it's getting a proper sense of how it is relevant and lastly I'm going to cheat by dividing bullet point three into one opportunity and one barrier so the opportunity we discussed was higher resolution data and how that can facilitate better modelling and better understanding and in terms of barriers one important one that came up which I think will probably come up repeatedly during the workshop is the sort of the incentives of the lack of them to do transdisciplinary research possibly in particular when dealing with something that has such a long time scale relative to the typical timescales in other disciplines like economics and the social sciences so I hope that wasn't too wordy there you go and Tim did you want to jump in on anything there you did a great job Simon all I'd all I'd add to elaborate is that this theme of how the social tips and causes tipping in the natural systems and vice versa how the natural systems might trigger tipping in the social systems kept coming up it was as if we were drawn to a a longer term view of the humans in the earth system as well seeking to understand how did we go through like the tipping point from no real economic growth to suddenly this persistent growth and in just the last couple of hundred years and whether you know there's a need for new social theory almost to address basic questions like whether the social dynamics have changed fundamentally in this what's called modern growth very gene by the long-term economic growth there is thanks that was that was a great way to kick off pretty impressive for doing in you know 27 minutes plus or 29 minutes plus 30 seconds of of recap so from from my session we spoke about cascading risks risks over the last thousand years over the last millennium I'll focus on just a few of the things that came out there was a concern that social tipping points are not well understood in general and some of this is about a lack of knowledge some of this is about the time periods in which we're talking as we go back and forth between these m