The Growing Risk of Climate "Tipping Points": Scientific Evidence and Policy Responses

Friday, February 4, 2022
Christophe Van Der Perre/REUTERS
Peter Cox

Professor of Climate System Dynamics, University of Exeter

Kelly Wanser

Founder and Executive Director, SilverLining

Stewart M. Patrick

James H. Binger Senior Fellow in Global Governance and Director of the International Institutions and Global Governance Program, Council on Foreign Relations


Stewart Patrick: Welcome to this roundtable. Today we're going to be discussing an issue that was addressed by no less than Tom Friedman in his latest New York Times column this week: the possibility that, thanks to global warming, we may be approaching critical tipping points in important components of the earth system.

Many of us, of course, are accustomed to thinking of climate change as something of a gradual and linear process, mirroring the steady accumulation of greenhouse gases in the atmosphere. The latest IPCC report on climate change left little doubt that Earth's current trajectory is dismal. We're on course to blow well past the Paris climate targets, and the Glasgow pledges do not change this.

Today we'll be discussing something even more worrisome: accumulating scientific evidence that rising temperatures may in fact reach critical thresholds in the subcomponents of the earth system in ways that themselves accelerate climate change with dire consequences. We will be discussing what these nonlinear discontinuities might look like and how they should shape or expand humanity's portfolio of strategies for managing climate risk. That portfolio currently consists of emissions abatement, adaptation and resilience, and carbon dioxide removal.

We have two great speakers to walk us through the science of tipping points and its implications for us and global policymakers. I won't try to summarize their sterling biographies, which you undoubtedly have.

Peter Cox is a professor of climate systems dynamics in mathematics at the University of Exeter, where he leads the university's interdisciplinary work on climate change and sustainable futures, with a particular focus on climate biosphere interactions. He has been a lead author of the last three IPCC assessment reports.

Kelly Wanser is the executive director of SilverLining, an independent, nonprofit organization dedicated to ensuring that society has sufficient options to address climate risk. A serial technology entrepreneur, she's helped shape and help fund critical legislation on atmospheric science. She is also, fortunately for me, a member of my advisory committee for a CFR special report I’m writing on sunlight reflection, also known as solar climate intervention and solar geoengineering.

Peter is going to begin by giving us an overview of what we currently know about climate-induced tipping points, how to think about these thresholds in their probabilities, and which ones might be of greater concern over different timeframes, and also press some of the research and methods we need for greater clarity.

Kelly will then address some of the policy implications of these emerging findings for the U.S. and other governments, including for identifying and monitoring potential near-term tipping points, dampening their consequences, and perhaps, if possible, even preventing these abrupt transitions. So, with those preliminaries, over to you, Peter. Thank you.

Peter Cox: Thank you, Stewart. Just going to share my screen now folks.

Peter Cox: So, it's a great pleasure to be here. As Stewart said, I’m at the University of Exeter in the UK, and I am part of a group of scientists there working on tipping points from a mathematical and also from a climate research perspective.

The stuff I’m going to share is thanks to Tim Lenton, who is a professor at Exeter; Paul Ritchie, who is my postdoc; and Isobel Parry, who is a master student who has been working with us all.

I wanted to give you some rough idea, some sort of introduction that Kelly will build on, about what we mean by tipping points and how the issues about tipping points have become more prominent in the latest IPCC report—and, in general, actually. So, it's about the scientific evidence and research frontiers.

There has been talk of abrupt changes in aspects of the earth system climate system like, for example, the Atlantic circulation, for a while, but actually, the first paper that laid down all the possible abrupt changes or tipping points that might occur was this paper by my colleague, Tim Lenton, which was published in PNAS in 2008. You can see here a list of possible abrupt changes that might occur under climate change. I'm going to talk about two of these in particular, very briefly. I already mentioned the Atlantic Ocean circulation, which is what we would term a slow tipping point. That's not to say that you don't get committed to change, but that it takes a while for the change to manifest. And the second one that has been particularly close to my own heart is the possibility of dieback of the Amazon Rainforest under climate change, and that's what we would call a fast tipping point—more on that in just a second.

So those tipping points were proposed by Lenton et al. based on paleoclimate evidence and modeling runs from climate models and simple models often, but also abrupt change and tipping points have been detected in the climate models that were used in the last IPCC report. You could see it in five models. This is from a paper by Drijfhout, I think also in PNAS, showing abrupt changes seen in various models, in the Arctic, and in Amazonia, and lots of locations associated with those tipping points to Tim Lenton pointed out.

And so, in the last IPCC report, which I was an author on, as Stewart said, we finally got a bit more on tipping points into the report. But actually, there's very little analysis done on abrupt change in complex models, partly because it's difficult and partly because we're always obsessed with climate change and global warming as a function of emissions.

So, this is a definition of a tipping point used in that report that came out late last year. A tipping point is a critical threshold beyond which a system reorganizes, often abruptly and/or irreversibly—and back to that in a minute. And a tipping element is a component of the earth system that is susceptible to a tipping point. So that is, for example, the AMOC, the Atlantic circulation, or the Amazon Forest dieback—or permafrost release that I think Kelly will speak about.

The other things, amongst many, that were said in the last IPCC report, the one that's still in draft phase actually in general, but the summary for policymakers is around. It said that there is evidence of abrupt change in Earth’s history, and some of these events have been interpreted as tipping points. I think it's fair to say it's pretty clear they are tipping points—abrupt changes before we start to foster the system.

And the probability of low-likelihood, high-impact outcomes, which is another name for tipping points really, increases with high levels of global warming. This is despite the fact that the models seem to show a relatively linear warming with emissions. There is definitely evidence of abrupt change locally.

And the archetypal tipping point, the sort of paradigm for tipping points, is what’s shown here: this is what's called a fold bifurcation by mathematicians, but it basically looks like a folded piece of paper. And the continuous lines here are our possible stable states, so the system. In this case, we've got them against global warming, so we might imagine some tipping element becoming more like this as a result of global warming. As you cross the threshold at about two degrees, just arbitrarily set here, then you enter a dotted line, which is an unstable state, and essentially the system state transitions to the lowest state. So that could be the case where the Gulf Stream shuts off or the forest dies back in the example I gave earlier. So basically, there's this notion of a very abrupt transition, and this is definitely an idealization which we've recently come to discuss in more detail in work by my colleague, Paul Ritchie, who I mentioned earlier.

So, this is the basic idea: you've got an unstable equilibrium, stable equilibria, and a transition between them, that can occur quite quickly—there's nothing to do with the forcing, it's based on the properties of the system, rather than what we're doing to it, once you cross that threshold, that bifurcation point.

My colleague, Paul Ritchie, produced a review in Nature, where we tried to extend this concept to consider the time scales of these different tipping elements. And when you've got slow tipping elements like, for example, ice sheet melt or the Atlantic overturning of circulation, you might have exactly the same underlying equilibria, but because the system is slow, you actually have an overshoot in a transit climate change, such that the transition takes a while to manifest, and this is important because it means that, in principle, for these slower tipping elements, you can imagine overshooting them, detecting, overshooting, and reversing it. And there's a couple of questions about that that we can discuss later. So, this is the example that Paul Ritchie had and, for example, for the AMOC, where you might have a rather large overshoot of the threshold, if you stay on the upper branch here, you might not have a transition.

And this means, in principle, if you could detect you’re over the threshold and you had a mechanism to return to it quickly, you might save yourself from such a transition. So, a big question from my perspective, then, is how would we know that we are over the cliff edge. Actually, we don't have accurate methods to do that, yet; there are a few ideas about the way system resilience varies with time, but that is a key question.

So, what Ritchie concluded is that fast tipping elements, like forest dieback, and these are things that might take decades to unfold, determine the dangerous peak warming, but slow tipping elements, like ice sheet melt or AMOC collapse, determine the dangerous overshoot of thresholds, especially how long you can overshoot them for. Turns out the duration of every shoot is more important than the magnitude.

I just want to say one final thing about Amazon Forest diabetic, which I originally brought forward as a possibility, in the early 2000s, and then I convinced myself that the models were overestimating the sensitivity of the system, and I think they are in some ways, but recent experimental data and the latest model projections are much more convincing.

This is work by Isobel Parry, the master student I mentioned earlier, and these are—I'm sorry the labels are quite small—but these are seven separate system models to show evidence of tipping points—the red areas are abrupt changes in forest cover—and the global warming scenarios, and this is something that we haven't seen quite so coherently as before. And it is connected with drying out in these regions in most models.

Okay, so I'm going to conclude. Abrupt changes in tipping points are important because they may dominate the impacts of climate change, quite apart from whether they affect how global warming varies with emissions—that still looks to be quite linear in these models even where they have tipping points.

The different timescales are of elements matter, especially in the rapidly changing contemporary planet. We're not in this paradigm of returning a system in equilibrium state—we're pushing it quite a long way away from that.

And, as a result, it may be possible to temporarily overshoot thresholds to slow tipping elements and reverse-out, if you have the mechanisms to do it, but this is much less feasible for fasting elements like forest dieback. And I've just briefly shown you that there's some localized Amazon Forest dieback evident in a number of the latest models, which is a new thing that we hadn't seen before. And I would just say that much more needs to be done in analyzing abrupt changes in tipping points in these latest models. We look at lots of variables, but we rarely look at abrupt change in them and, when we do, we find all sorts of things. This actually requires new methods to detect and forewarn a tipping point when you've got a rapidly changing environment, which is the one we're in now.

Thank you very much, Stewart.

Stewart Patrick: Thank you very much, Peter. That's terrific, and I'm sure there are going to be a lot of questions out that we can get to about how you rate some of the importance of some of these and probabilities, and also timescale issues—but before we get to that, and I hope that our participants are thinking of some great questions, let's turn things over to Kelly, to provide her insights.

Kelly Wanser: Thank you, thank you very much, Stewart, for inviting us here and entertaining this really critical topic. And thank you, Peter, for a terrific overview of a little bit of the state of the science. I want to pick up where Peter left off to talk about, you know, we appear to be in some uncertain state with respect to the probability of some of these major tipping events, and one of the contexts for policy for this type of risk is disaster risk management. So, I am going to speak a little bit, especially from the perspective of the U.S. context, where we work very actively, about some analogs for thinking about this type of major systemic risk and how work in this area might fit and, in particular, I have a picture here of the Siberian permafrost, one of the noteworthy things about these tipping point risks is that we are getting reports from observational studies in the past year or two that there are observations indicating that the probability of these kinds of big tipping events may be escalating.

But these observations are relatively ad hoc and sparse, and so it appears that we see these things starting to emerge, but the information that we have is actually fairly weak. Peter alluded to that as well, and I'm going to talk about that a little bit further in the context of other kinds of programs that exist.

So, the first in terms of systemic planetary risk is the asteroid risk, which is meeting its popular culture. There is a program for mitigating the risk that an asteroid would strike the planet in a way that would have a global systemic effect. That program is run out of the Planetary Defense Coordination Office at NASA, and the proposed FY22 funding for that program is about $200 million. It's an active program developing technology for doing detection and mitigation of asteroids. So that is one sort of model for this type of work. Another is a study that was undertaken to look at the threat of the eruption of the Yellowstone supervolcano, which is a high-capacity volcanic threat. There was a study done in 2017 by NASA to look at the possibilities for mitigating that threat. So, were that supervolcano to erupt, it would be an existential threat to North America—and a global threat. So, they developed, actually, or they conceived, a $3.5 billion plan to mitigate the volcano that would include drilling sideways to pull thermal energy out of the volcano and even to use the thermal energy as part of an energy program.

And so, one of the scientists on both committees came to the conclusion that the supervolcano risk was actually significantly higher than the asteroid risk. And then, if we look at the sort of major tipping event risks that we're running now with respect to the climate system and you were to look at this sort of relative risk, especially since we have more than one type of tipping event risk here, right now, our funding against the actual risk profile of these global systemic events is probably steering towards the lower probability end of the spectrum, which is interesting.

But the design of these programs is also really interesting. So, the Planetary Defense Coordination Office has sort of three main features of the asteroid mitigation program: develop programs to find and categorize the at-risk events represented by asteroids, to warn, to coordinate, and then finally to mitigate.

And so that type of model is quite interesting when you think about other types of global systemic threats: how do we detect them; what type of coordination do we have with respect to their evolution, particularly as they begin to be proximate; and then what are our options for mitigation and do we have mitigation strategies in place. And so, if you think about the tipping point issue, and we start out with what Peter alluded to, which is the sort of find and warn gaps. At SilverLining, we spend a lot of time with U.S. federal agencies involved in climate research and some involved in policy, but we're particularly close to modeling new data types and capabilities. And right now, in the U.S. system—to the best of our knowledge and those of some of our agency partners—there are no concerted programs, to look at major tipping events, and particularly to look at them in the context of risk management.

And so, what we have seen, and reflected in Peters comments, is that there are academic studies and there are sort of elements of different climate programs and assessments, but they tend to be academically driven and the field has been a bit theoretical.

And so, one of the gaps, or a couple of the gaps that we see, one that Peter alluded to, is there are things to be done with current model studies to focus on the dynamics around tipping events that have been present in simulations and the precursors of those focus-study observational data that's there. They're even some observations of permafrost in Russia where there's microfiche we could look at it—so there's an opportunity to collect and collate data that we have in a concerted way that focuses on these questions and, particularly from our point of view, those tipping event risks that are both near-term and systemic.

And then secondly on the observational side, and I'll talk about that in a little bit, the question is, are there things that we could rapidly roll out to improve spatial, temporal, and resolutional coverage of the observations of these critical systems where we have a much more ad hoc view, particularly of this sort of in situ information from the surface, the air, and the ocean, that we would like to have.

And then finally, with respect to mitigation, so again to Peter's comments about the possibility that some of these evolving tipping threats might have the potential to be mitigated—either reversed or forestalled—if there were the means of rapidly reducing the warming stress on those systems. And one of the gaps that we have today is that our investments in mitigation of warming are primarily focused on things that operate over longer periods of time—both longer periods of time in terms of the scale-up of their influence to be able to meaningfully influence the climate system, and then the time it takes for greenhouse gases to evolve out of the climate system in a way that significantly affects warming.

So, we at SilverLining became concerned about this sort of near-term gap: the ten, thirty, forty, year-gap that we have in options that could significantly reduce warming quickly, even within a matter of years. And that question was looked at by the Royal Society in the UK starting in 2009 and again in 2012, and more recently in the U.S., starting in 2015 and again last year.

I'm showing here a couple of reports from last year, which are jointly related to this topic, although neither of them addresses it explicitly. One is the National Academies report on recommendations for the direction of the U.S. Global Change Research Program, and one of the big thrusts of that report was recommending a shift towards a risk management perspective. That was kind of one really interesting element in thinking about the organization of U.S. research and climate.

And then the second was a report recommending a research agenda and elements of governance for research on one of the most promising methods, from the point of the scientific community, of reducing warming and in the climate system quickly.

And that's the image that I'm showing you here, which is going to become an animation.

So, when scientists and scientific bodies went forward with assessments of what were the most promising options for reducing warming in the climate system quickly—within a decade or within even a few years or less once developed—the most promising recommendation for research was increasing the reflection of sunlight from clouds and particles in the atmosphere.

And what you're seeing here is a simulation from NASA of the reflection of sunlight from particles and clouds in the atmosphere, and scientists estimated, with lots of caveats around uncertainty, that it might be possible, by increasing the reflectivity of the atmosphere by just one percent, to offset two degrees or more of warming. There are a few different approaches that they've looked at closely, ranging from the outer atmosphere, the stratosphere, and inputting particles directly in a way that large volcanoes have done in the past, to brightening clouds in the lower atmosphere, the troposphere, which is actually a phenomenon that happens now as pollution particles are also brightening clouds in a way that is estimated to offset some of the warming that we would otherwise experience. So, these are potential approaches to the mitigation question. They are also very nascent in terms of the state of the research for a variety of reasons.

So, we at SilverLinging, working with our government partners and others, we've been talking to folks about the importance of the proximity of the problem, the nature of the uncertainty (we have a real discomfort with that uncertainty), and the high stakes. So, the first thing that we think might be important is to work with Peter and others to quickly develop a roadmap of the most important, immediate things to be done in terms of looking at some of these proximate risks, and then to begin a rapid expert analysis program to try to start to characterize the biggest and most proximate of these tipping event risks.

We actually have recommended some language in the FY22 and some money for the Department of Energy, which has some of both the sophisticated standard modeling tools, but also some of the other kinds of tools, AI and risk analysis tools, that you might want for that type of activity.

And then there are other things to be done in terms of the idea of a coordinated interagency program on near-term risks and interventions, and there is some language being discussed for the appropriations report as well on that; and then, in particular, on the possibility for some rapid skilled observation programs, and I'll talk about some possibilities for that that might not be unrealistic; and then in the policy sphere, with respect to having some programs emerging that are rapidly looking at what analyses can we do, how can we develop/rapidly generate some risk information, and, at the same time, get some observations scaled out to these at-risk systems; then working on both scientific cooperation internationally and building our community science, so we can get sort of rapid research input on different aspects of the problem quickly; and then, looking at the context in terms of the disaster risk management and emergency preparedness missions and mandates that are in play and in question. Right now, these topics don't live in our disaster risk management emergency preparedness missions, so that's something for us to think about.

I'll end on the note in terms of observations. The first question is of finding. We think that there's a possibility for rapidly increasing our in-situ observations of, in particular, greenhouse gas sources, including sources from natural systems like permafrost and changes in forests. One way to do that is by using platforms of opportunity. There's a convergence of technologies that make it possible for us to put sophisticated instruments on platforms that are already there. And NOAA piloted a program with Alaska Airlines and Boeing to put sophisticated greenhouse gas monitoring instruments on their ecodemonstrator aircraft. And we're working with them on trying to scale that program first with Alaska Airlines to their cargo flights that do hops around Alaska.

So that could give us some rapid traction on visibility on some of the greenhouse gas emissions from natural systems in that region of the Arctic. We're pretty excited about similar opportunities that exist. We think that it's both critically important to increase our information resource-wise and observations—and also that it's possible.

And we need to work in the art of the possible fairly quickly to manage these risks. So, with that, I’ll turn it back to you, Stewart. Thank you very much again, and I look forward to the conversation.

Stewart Patrick: Thank you so much, Kelly, that was terrific. I really enjoyed it, and I liked the analogies to other aspects of disaster risk management and seeing, given the gravity of the climate emergency, the degree to which perhaps we might want to invest a little bit more in some of those thinking about different methods of finding and ideally responding to this crisis.

I want to invite all of the participants on the call to please use the raise hand function if you have a question you'd like to offer to Peter or to Kelly.

Most immediately, I guess I'll probably turn this to Peter. I'd love it if you could share your slide deck again, just to the map picture, in particular. That was quite fascinating. I know you focus mostly on the AMOC and the Amazon Rainforest dieback. There are obviously a number of other tipping points that folks have identified. Obviously, our knowledge base is still improving, but if you were going to prioritize some of these things, or could you just describe a little bit more about the nature of those particular tipping points? Is there any sense of sort of the time horizon over which these would be occurring? And the other question, which is sort of a more general question, is one of the frustrations of, well not frustrations, but one of the questions I have is beyond addressing greenhouse gas concentrations generally, are there things that, when it comes to these different tipping points, have been identified or things that one could do to adapt or build resilience against in specific contingencies? I know that there have been ideas about even building physical structures or pumps to prevent the breakup of Antarctic ice sheets, for instance.

So, I realize that’s a tall order, but it'd be great if you could give just a little sort of a brief summary of some of the other tipping points folks are looking at.

Peter Cox: So, these are tipping points that were, as I said, proposed in 2008. Some of them, we think, are more associated with air pollution, so the Indian monsoon and multistability are more likely to be caused by aerosol pollution.

Permafrost and tundra loss is the one that I think we were most concerned about in the last IPCC report, in the chapter I was involved in about the carbon cycle, and Kelly mentioned that. That's basically because when permafrost melts, you get a lot of biogenic emissions of methane, which is a strong greenhouse gas, and CO2.

There are issues about what you mean by a tipping element. It's irreversible in practical timescales, so we use this deliberately loose definition in the IPCC report. It takes longer to recover than it takes to live and the time it takes to lose it.

So, I think permafrost and tundra are ones that could accelerate global warming; most of the others are local but no less important for that. I mean, if you live in the Amazon Rainforest carbon release would be important for climate change but very, very important for you, and I think many of our impacts of climate change that we worry about are going to be dominated by these extreme events and the risk of them—same with forest dieback in Boreal regions that might be a result of diseases that are more prevalent under warming.

Some of the other ones are slower. They're like slippery slopes: melt of the Greenland ice sheet. We’ve got an idea about where the threshold for that is and it's quite low. But it's also a slow one, so there's a possibility of backing out. We're not showing much sign of doing that through committed mitigation yet, but there is a possibility of backing out.

These changes have been added to, but these are the main ones, I would say, and feedback from permafrost loss is one of the key ones that could accelerate global warming. The others are dominant locally and can have an impact on the global climate, but I think in some ways we've gotten a bit obsessed with the feedback to the global when in fact when we're worried about the sort of risks that Kelly was talking about, they tend to be local. I mean, people experience an abrupt change locally, and it is catastrophic, regardless of whether feedback significantly impacts climate change or not.

Stewart Patrick: One of the things that would be extremely interesting is the degree to which from there would be analysis, in addition to identifying and monitoring, perhaps early warning of some of these impending risks, one could imagine that, like climate change generally, many of these tipping points would have significant sort of distributional consequences for, you mention, the local aspect and certainly the regional aspect of some of these things. In certain areas, some of these things could have catastrophic effects, for instance, the change of the monsoon patterns.

Peter Cox: Absolutely, so one of the things that has been suggested, and there's good evidence of this, is that for some tipping points, when you're close to it, the sort of crazy, equilibrium state with a static, steady-state, then you get a generic signal, which is called critical slowing down, in the variability of that system as you approach the tipping point, and that's basically like the well that the system sits within getting shallower and wider, so you get larger and slower oscillations—this is the critical slowing down. And that does work for slower tipping points, so, for example, recent papers have suggested the Atlantic overturning circulation is slowing down, and therefore it's becoming less resilient.

It is a slightly more difficult thing and less reliable when you have rapid forcing, and that's the thing I was pointing out, I think. We probably need more system-specific precursors and early warning systems for these tipping points. In the case of the Amazon Rainforest, we found an interesting one, which is that if you just look at the amplitude of the temperature cycle in the Amazon, it tends to grow when the dry seasons get dry and therefore offset, and that is a precursor in all these models to dieback becoming a higher risk. So, there were things like that that can be measured. In this case, we've got reasonable measurements of those maximum temperatures, but in other places, we don't have good measurements really, of methane release and permafrost, for example.

But those sort of things, these sort of system-specific warning systems, it would be fantastic if we had them for all sorts of reasons, quite apart from what we do subsequently, and—

Kelly Wanser: If you don't mind, I just wanted to pile on that a little bit. What we think is so important and interesting about Dr. Cox's work is that there are some methodologies to apply, that the methodologies for kind of the way to go about the problem translate across these systems, and then there is specific work you need to do that pertains to the function of each system, but getting methodological approach and starting to do that in a very concerted way—it's exciting and promising that that's there to be done, and it's also concerning that's there to be done.

Peter Cox: Yes.

Stewart Patrick: Kelly, I'd like to just engage you on how, as I mentioned, we have this portfolio of responses to climate risk. There's adaptation and obviously, in particular areas, there's going to be a need for greater adaptation. As I mentioned, I'm not sure how plausible they are, but there are also the technological sort of efforts to try to, in Antarctica, reduce the amount of impact of ice sheet breakup, etc.

But there's adaptation, obviously, which many people who are going to be in the regions and localities that are influenced by this are going to have to deal with. One can imagine just the extraordinary effects if the AMOC, the Atlantic Current, were to basically shut down. In effect, presumably, the ramifications would be huge for most of the folks living in temperate or formerly temperate Europe.

But so, there's adaptation. Then there's emissions abatement. This obviously should make folks more and more aggressive in terms of the sort of emissions reductions. There's carbon dioxide removal. The problem with carbon dioxide removal, as well as emissions abatement, is it's taking a long time for many of these technologies to go to scale.

Do you detect or think that there's going to be a greater appetite for at least looking into prospects for sunlight reflection if it's framed—because it's obviously been highly controversial—as solar geoengineering? Do you think that there is an opening, a political opening, for broader discussions of sunlight reflection as a contribution to this portfolio, as long as it's framed as a supplement rather than as a replacement for some of these other strategies?

Kelly Wanser: Well, I’ll start in a practical sense by saying that's been our experience, but I think I'll answer your question in two different ways.

One is thinking about disaster risk management. One of our advisors is the former head of research at Goldman Sachs, and he talks about the fact that climate policy to date has not actually been risk management in the sense that risk management looks at the full spectrum of risk, including planning against some of the worse scenarios and fluctuations and their probability. So, if you look just from a disaster management point of view, where we say well, let's look at scenarios where the probability in the evolution of these tipping events is on the higher side and then what's our plan. That's how the asteroid planetary defense system works and thinking about the Yellowstone volcano.

So, then, if you look at sunlight reflection interventions and at least the activity of studying them and assessing them, in the context of a disaster risk management strategy, they start to look a little bit less radical because it's not about tradeoffs against bringing the system to a healthy sustainable state in terms of emissions, it's about the risk management of what are we looking at in terms of human life, infrastructure, economic security, and national security.

And so, if you take the example of South Florida where my parents live and the tipping event like the collapse of the big ice sheets and a pop in sea level rise, then you've got a real disaster risk management issue for real people in Florida and elsewhere in the world. Then, if we look at that we say, what tools do we have in the portfolio if we're in a precipitous situation with respect to them.

We're a science-led organization, so we're just looking at where the scientific community has landed on the best available options, which is how we end up with sunlight reflected from the atmosphere because, as they've looked at the other options, either in terms of scale or sort of the systemic problem that warming moves around, it's sort of landed there in terms of places to start.

So, what we've seen in the dialogue so far with policymakers is that it's been a less controversial dialogue than it is in the media, where the conversations are in the more abstract context about some of these technologies.

Stewart Patrick: Thank you. We have a question from Stu Feldman. Did you want to ask a question?

Stu Feldman: Thanks. Two questions. What is the global impact of Amazon dieback? Is there a simple quantification, not the distributional-local but the global result, since we seem to be heading quite well toward it?

And Kelly, nice to see you, I'm very curious about your line about international cooperation and observations. I'm curious, what is there? What significant work is already underway? What holes are there, because the U.S. provides a fair fraction of all the satellite data and we're not too good at sharing all of it, and so forth? So, I'm just curious what the state is. Sorry, two questions.

Stewart Patrick: No worries. Mr. Feldman, could you identify yourself just by affiliation?

Stu Feldman: Sorry, Stuart Feldman, chief scientist, Schmidt Futures.

Stewart Patrick: Super.

Kelly Wanser: Do you want to start Peter?

Peter Cox: Yes, sure. I’ll do the Amazon dieback one.

In the latest models, we don't see large-scale dieback, we see this kind of speckly pattern, so that's why I mentioned the fact that it’s the impact rather than the feedback, but in the early results that we got where we did get a lot of scammers and dieback, we lost about 150 gigatons of carbon over a couple of decades. That's something like ten to fifteen years of current emissions.

So, it's not huge in terms of the addition to effective CO2 basically because we're emitting so much so fast. But it is a significant feedback, nonetheless, a bit like the methane feedbacks. The methane feedbacks would be amplifying the rate of warming, they wouldn't change the whole system to a different state, which is what some people have said, but it would certainly change local parts of the system radically in ways that would have bad impacts.

It looks like it's in the order, in the worst case, of about ten to fifteen years of global emissions, if the Amazon went completely.

Kelly Wanser: So, I'll answer the second part of the question about the observations. In particular, we follow quite closely work on the observational category, particularly the work of the NOAA Global Monitoring Lab. One of the big challenges is the limitations of what remote space-based observations can do. I think that it's been exciting in terms of the possibility of having the comprehensive observations you can get from space, but it's still the early days in terms of the techniques for leveraging space-based observations with algorithms to determine what's happening down below. Where you run into problems is that there are things you can't see directly from space, and space observation programs try to use algorithms and ground-truthing to then interpret what's happening down below.

But the state of the art today means that there are some important things that you can't do, including local attribution of sources of greenhouse gases. And this is a problem for doing monitoring and detection for national commitments, for corporate commitments, but it's a really important problem for looking at changes in natural systems in terms of their emission of greenhouse gases. That's where we at SilverLining have been a little bit surprised at the weakness of surface and aerial in situ observations and subsurface observations. The same problem exists for having really widespread, adequate observations of ice melt under the surface. So, these gaps mean that we are flying blind in a lot of cases where we're very ad hoc.

That's where, in terms of the tipping point observations and the opportunities that Peter’s work presents, that if you can analyze some indicators that indicate that you're approaching these changes in these systems and then you could go after widespread monitoring like we do with earthquakes, that layer appears to be mostly missing and not terribly solvable from space.

Stewart Patrick: Thank you, Kelly. The next question is from Adam Wolfensohn.

Adam Wolfensohn: Hi thanks very much for a super interesting, if not depressing conversation. So, moving off of that, your colleagues, I think I’m right, Professor Cox, at Exeter, also introduced the concept of energy system upward scaling to people as a more positive approach and using similar dynamics where people could manage a system to shift more rapidly, than perhaps you know we might think, to a low carbon energy system and such pathways, particularly in emerging markets. I wonder if both of you could talk about the potential from a mitigation perspective of targeted interventions that might [induce tipping points] we want to occur, where you have a more rapid energy transition, and how we might encourage those practically. Thank you.

Peter Cox: Very good question Adam Thank you, and we are thinking more and more about what you might call positive tipping points and things that we would like to happen—abrupt changes, transitions, we'd like to see happen and would be necessary to deal with the climate problem where that happens. I think there's good evidence that human-social systems are more prone to tipping points, actually, than even the climate system, so I think there is some hope there, Adam, that some of the things we're learning about tipping points in the climate system might be useful to promote positive tipping points in human and social systems.

Some of the techniques that Kelly spoke about for detecting when a system is approaching a possible bifurcation point and essentially choosing which direction it goes can in principle be applied to systems like networks, which are more consistent with the ways socioeconomic systems operate. I think we are working in that direction. I think it is one of these nice things where you get a transfer of knowledge from one field to another, but because we're talking about nonlinear systems, there are some generalities here that can be used in both directions, like detecting where you're getting a dangerous change you want to avoid, but also, as you're implying, Adam, in some systems, prompting a change when it's most sensitive to an input.

Kelly Wanser: I’ll layer onto that as well. I also agree that there are these opportunities for applying these techniques across the human systems, and particularly in regards to innovation and technology transition. Technology transition in particular because that's where you've got this sort of bifurcation of choices and ways to tweak and tune the system for those things to go fast or slow. A lot of times the policies we have are placing downward pressure on the innovative transitions that could accelerate progress.

So, I do think with some of these techniques, looking more consciously in a systemic way of hey, if you're trying to scale this, through the industry, what does that look like and what do you tune, there's really promising and hopeful opportunity there, which is one of the reasons why we want to make sure we address this ten-, twenty-, thirty-year time-horizon gap, because the potential of innovation and disruptive changes to human systems that really get traction on the greenhouse gas problem, I would say those are actually pretty strong.

Adam Wolfensohn: Thanks very much to you both.

Kelly Wanser: One more thing I'll say related to that, because I was at COP26 this year for the first time. I was told by people who were veterans that, even against a few years ago, at COP there was a massive corporate presence, and indeed there is, it’s like a trade show, but that corporate presence really represented a big, sizable shift in the involvement of industry in the financial sector of climate change.

So, the level of investment that's going into the forward path of changing some of these practices and approaches is massive and it's pretty bound to have a systemic effect. It will be interesting to understand and study that more and help tune it correctly.

Stewart Patrick: One of the things that I think needs to be a priority, both for research and also policy engagement on this issue, is, obviously not just in particularly highly divided societies or politically divided societies, to get folks to have tipping points in messaging and in sort of the recognition of the gravity of the situation. There are, I agree, Peter, some really interesting lessons from history where there are great divisions, but then sometimes sort of staring into the abyss or the prospect of a hanging concentrating the mind can induce some significant policy innovations and changes.

But I think it's also important, both in terms of the basic science, I would imagine, but also in terms of building coalitions, that this be as international a process as possible—particularly the climate field, which has often seen lots of North-South fissures and disputes about historical responsibility, and also the burden of adjustment in these sorts of things, that things like tipping points would, I mean although some of them will have much more regional effects, perhaps reinforce the notion that we're all in this together.

With respect to the research first Peter, could you talk a little bit about what you think the state of play is in terms of climate research around these issues and including the networks that might involve folks from the Global South, and then Kelly, I know that you’ve had some experience with building networks from an advocacy as well scientific perspective.

Peter Cox: You're absolutely right, Stewart. These are global problems, even if the impacts are felt most strongly locally, which is often the case, and we've got collaborators in Brazil, of course, when we're looking on Amazon issues, where all the expertise lies. The observational-based concerns about the Amazon Forest turning from being a sink for carbon to becoming a source actually come from large-scale measurements of tree diameters’ free-time—an amazing activity that's done in Brazil. We're absolutely dependent on those, and they’re rare, in terms of raw, ground-based data that we've got, but they give us some idea of what's going on. So, the collaboration is absolutely key.

The issue we are finding with all sorts of interventions, even with CO2 mitigation, is, of course, that you have to get an agreement across the globe to do it, and the governance issue with SRM is especially challenging because there are winners and losers with anything you do, actually—especially with SRM. I think that's one of the things that people get nervous about, is this idea that we might have to agree on something when we can't agree on the obvious, which is to cut emissions.

But in terms of the rate at which you can do things, as you hinted Stewart and Kelly said, if you believe that you're approaching a threshold, there aren’t many options available to you that are fast enough in the conventional way of thinking about these things. Carbon capture would be too slow in most cases­—maybe for the slow tipping points you could do it, but for faster tipping points, there's no chance of that. So, we're always looking for things that might be, if we detected you're over the edge, what might we do about it, and they're a relatively small number of things that have to be fast and rapidly acting.

Stewart Patrick: Great, and Kelly, and then we are going to have a question from Kilaparti Ramakrishna.

Kelly Wanser: I'll be quick, but I would echo Peter’s point that the scientific cooperation between people in different parts of the world for a variety of reasons is profoundly important, and there are really good mechanisms in place actually especially around climate and environmental issues like the World Climate Research Program in the Western Hemisphere, the Inter-American Institute for Global Change Research, and so on.

One of the proposals we have for FY23 is for the State Department to increase funding to those organizations in these particular areas because typically, in our experience we also have funded Global South researchers, there's a question of having those programs there that support scientific cooperation—and then there's funding. There's always a need for funding, and I'll say that to the philanthropists here too: funding Global South research on these topics is really important—and the technologies they need to do the research.

But to the point of having a healthy approach to governance, our experience in observation is that those efforts that are strongly science-based and that are able to draw from strong scientific information or resources, like the Montreal Protocol, for these kinds of acute questions with environmental systemic risks, where you know the stakes are high, more information and a more scientific organization may help the dynamic quite a bit.

So, we tend to take the approach of let's try to move things through a decision process that’s science-board and science-based, and open, so that the world can cooperate on these decisions, because there may be winners and losers, but, more likely, as we look at these questions and what the options are, many of us are in the same boat.

So, we’re optimistic that with information in an open ring, you might have a better shot at agreement than you think.

Stewart Patrick: Thank you. Can we have Kilaparti Ramakrishna, please.

Kilaparti Ramakrishna: Thank you, Stewart, for the very important discussion. I'm glad that we're having it now. For some time, we’ve known about the tipping points, the biotic feedbacks, and so on and so forth. In fact, I can't believe I’m asking this question, but something that has been said in this conversation prompted me to ask this.

We are talking about increased attention by every stakeholder in society to the climate crisis and the solutions. Something that Kelly also referred while talking about COP26 was about the number of private sector entities that are there. As we measure, I know it is more of a social-sense question for the IPCC authors, but as we measure the tipping point and what we are doing to the natural systems, is it possible to measure tipping points in terms of governmental and societal action? Can you see this going in parallel—one really going downhill in terms of the natural systems, and the other in the more positive direction—and would that be seen as a race? Somehow, on the other, will we see that, at the end of the day, the positive actions by society are going to meet the challenge of the tipping points and the diebacks, etc., etc.? Thank you.

Stewart Patrick: Thank you very much. Kelly, would you like to—

Kelly Wanser: Speak to that, yeah. Thank you for the question, because it's a great question and I think our concern is that there's uncertainty as to that question. One of the big problems is that we don't actually know the magnitude of the uncertainty, but there's a possibility that changes in human systems might address and prevent all of these major tipping event risks, but there appears an increasing possibility that they won’t.

So, we're more concerned with the nonbinary question, which is hey, can we focus on understanding those uncertainties better, and can we look at what our strategies are for the case that's not good—and make sure we have some because of the magnitude of the risk. So, we're less concerned about the binary question. We want society to push as hard as possible, whether it's like fire insurance or the ripcords that you pull when you have a problem.

Hopefully, you don't have to have that but, in the event that we've got some pretty substantial risks running, having those options, or at least evaluating them, seems like a really, really important thing at this time.

Stewart Patrick: Just before turning it over, Peter, it seems that there's also the different methodologies and dimensions of political tipping points, and political deliberations, and the political climate that goes into that, and then there's, of course, the scientific process and trying to get those two processes in timetables lined up and latched up. And then there’s the question of how much scientific certainty versus uncertainty do we need to have to be able to take out some of these insurance policies that Kelly, you were talking about. But, Peter, over to you.

Peter Cox: So that's another very good question. I think I get the sense that there is a high profile amongst populations worldwide in the importance of dealing with climate change, but there are lags in the system—they're quite large lags in the system. That means, based on what we can see, if you look at the model of the CO2 record, it's kept on going up—there's no sign of it stabilizing. Emissions have kept on going up, apart from mere, small perturbations associated with financial crisis and briefly with the COVID pandemic, but they carry on going up. So, we are hopeful that there will be a tipping point in action on climate change, but it's not evident yet.

I'd be interested to see whether there's any way to detect such a thing, which I guess is part of the question. But that leads you to the view that we are probably going to cross thresholds that we haven't already, tipping point thresholds of various sorts, and we are on the lookout for those. Then you work out what you might do about those, and some of these might be local actions. You could imagine, for example, irrigation for a while, if you had a peek dealing with a drying, or changing vegetation type, or that sort of thing, as well as these more radical interactions that and interventions that Kelly spoke about. They need to be relatively quick, and you need to get enough warning of them.

So, I think, yes, we're hopeful of a tipping point. I don't see why there shouldn't be a tipping point, and there is arguably a tipping point in innovation, with regard to renewable energy. It takes a while for that to feed through, but, based on the current knowledge of tipping points, we are still very light across the Paris targets as Kelly said, and associated with those thresholds that we believe are out there, those are uncertain thresholds so we can't be absolutely sure, but, therefore, the risk increases with every point one of warming and we need to be aware of that. That means better action, but where we've got lags in the system, it means having ways to deal with things that might need emergency interventions.

Stewart Patrick: Well, thank you very much, both for trying to reinforce our timescales of the ongoing climate crisis, the science scientific inquiry, and then the political adjustment, and trying to make sure that those lags, or chasms in some cases, between those aren't so great that we find ourselves in a world of hurt.

This has been really, really interesting, and I realize it's just a beginning of a fascinating research agenda for you, Peter, where there must be so many uncertainties. One could imagine a significant increase in research to support your work and that of your colleagues can be highly important. Kelly pointed out the importance of the U.S. government and other governments around the world taking this agenda seriously, funding this agenda, and also, perhaps, concentrating the mind on the near-term climate risks, as opposed to something that might happen in twenty, fifty years, or beyond.

I think that, in Washington, we've only begun to grapple with those things, and perhaps that's true in other capitals around the world, but with those closing remarks, I just want to thank both of you for lending your time, and I hope that Peter, we can stay in touch. I'm in touch on a regular basis with Kelly, because of the mutual project we're working on, but Peter, I hope we will have a chance to hear from you again and wish you all the best in your research endeavors.

Peter Cox: Thank you, Stewart. Thank you, Kelly.

Kelly Wanser: We appreciate it.

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