A Sustainable Future: Prof. Tim Lenton, on Planetary Boundaries, Early Warning Systems and Climate Tipping Points | Man Institute (2023)

What does science reveal about a potential collapse of the Earth system? Listen to Jason Mitchell discuss with Professor Tim Lenton, University of Exeter, about what’s at stake when we talk about planetary boundaries, early warning systems and climate tipping points; how the supporting science and empirical evidence have expanded over the last decade; and why GAIA 2.0 represents a powerful framework to reinforce global sustainability.

Recording date: 17 April 2023

Tim Lenton

Tim Lenton is Professor of Climate Change and Earth System Science at the University of Exeter and Director of the Global Systems Institute. His books include Revolutions that made the Earth and Earth System Science: A Very Short Introduction. Tim’s current focus is on understanding key events in the coupled evolution of life and the planet and on early warning of climate tipping points. He and his team are developing an evolutionary model of the marine ecosystem. Tim is a Fellow of the Linnean Society and a Fellow of the Geological Society.

Episode Transcript

Note: This transcription was generated using a combination of speech recognition software and human transcribers and may contain errors. As a part of this process, this transcript has also been edited for clarity.

Jason Mitchell:

Welcome to the podcast Professor Tim Lenton. It's great to have you here, and thank you for taking the time today.

Tim Lenton:

Thanks, Jason. I'm looking forward to chatting together.

Jason Mitchell:

Excellent. So, Tim, I've really been looking forward to this conversation, but let's start with some scene setting. What are climate tipping points? Can you describe their fundamental properties? And how do feedback mechanisms amplify or counteract the effects of climate change?

Tim Lenton:

So a tipping point in any complex system, Jason, is whereas small change makes a big difference in the outcome for that system. And in the climate we're talking about small changes in say global warming causing big changes in parts of the climate system. And I've kind of listed a bunch of bits of the climate system that we call tipping elements that could pass a tipping point at different levels of global warming. And in every case there's a key role for feedback loops, especially what we would call amplifying feedback. So a tipping point can happen, you can get a large response from a small change when you have really strong amplifying feedback within a part of the climate system in this case. So that means that small change in forcing we would call it provokes a response within that system that amplifies the initial effects of that change in forcing.

And the whole thing is so strong the amplification that it's sort of self-propelling. You could take the global warming, the forcing away and the change might just keep unfolding by itself. So with the example of that, to make it a bit more concrete would be the green net ice sheet. As we warm it up and we cause net melt of the ice sheet, the top altitude surface of the ice sheet drops in height, and that puts it into warmer air, air which tends to make it melt more, which loads the altitude further and so on. And that amplifying feedback is strong enough to get to this self-propelling situation where it can just cause a whole ice sheet to collapse at some point.

Jason Mitchell:

Are tipping points artifacts of climate models or the real earth system?

Tim Lenton:

They're definitely part of the real earth system because we now have quite extraordinary records of earth history, both recent and distant history where we see instances of tipping points. And a classic example is during the last ice age, there are over 20 abrupt climate change events that affect, well, particularly the North Atlantic region, but the whole Northern Hemisphere and with repercussions in the Southern Hemisphere. So these are warmings in the North Atlantic region, the order of eight or 10 degrees centigrade and the order of one or two decades. So really rapid climate change. That's consistent as well.

And later on there's also abrupt cooling events before then some thousand or so years later you get another abrupt warming and so on. So that's one classic case, and there are others where we've seen abrupt climate changes and tipping points in the earth system in the past, and that was without us hitting the climate system hard with global warming, which just is the thing now that's got raising the risk of provoking tipping points in the near future.

Jason Mitchell:

Yeah. I want to explore this abrupt change when we talk a little bit later about climate modeling, but what's the relationship between your early work on planetary boundaries and tipping points? How do we go about establishing or even calibrating a safe planetary boundary variable if it doesn't necessarily have an obvious tipping point?

Tim Lenton:

That's a great question. So the thing I worked on first of the two was tipping points in the sense that with my friend John Chiang, when we were kind of coming up with this concept of climate tipping points and trying to list them in the early 2000s and through the mid 2000s. And then we'd kind of got a starting map and list of climate tipping points. It made it clear that for the planetary boundary of climate you could begin to define a level of warming beyond which you would be risking lots of these tipping points, so make a clear definition of that planetary boundary. But then I think it was 2007 that my friend, Johan Rockström invited us to the original workshop where we started to map out a broader set of planetary boundaries for other variables like nutrients and loss of biodiversity and water and so on.

And so I kind of came to that meeting and to the original concept of planetary boundaries with some specific examples of tipping points, not just for climate but for some of the other boundaries. I actually introduced the idea that for adding nutrients to the land that ultimately wash up into the ocean, there is a eventual tipping point where that risks tipping what we call the deoxygenation of the oceans, which have been a major catastrophic tipping point. So for a various planetary boundaries that we were drawing up on the big list or dial of those, we could bring evidence of tipping points as a clear rationale for setting a boundary safely before you got to that level. But for other planetary boundaries, it's not so clear that there are big scale tipping points that you can define the boundary from. In that case, we have to come up with other rationale and it's a little bit murkier or more uncertain, you might say, how to set a boundary? But that's just the nature of a kind of complex earth system. Some bits of it have these tipping point responses others don't.

Jason Mitchell:

I want to actually touch on the precautionary principle. The notion of the precautionary principle allows for the adoption of precautionary measures when scientific evidence is uncertain and the stakes are high as we're now talking about when it comes to climate, what is the precautionary principle for climate tipping points? How should we be behaving given how high the stakes are?

Tim Lenton:

Well, I think we should be doing everything in our power to limit the risk from crossing climate tipping points because they can be both abrupt and irreversible, and they pose in the worst case scenario, a kind of existential risk, I mean a risk to the stability of our civilizations and societies going forwards. So that's a strong argument for doing everything we can to limit global warming as close as we can to about one and a half degrees centigrade above pre-industrial. We're probably going to miss that target now and overshoot somewhat. But yes, the fact that every 0.1 degrees centigrade global warming above one and a half degrees seems to markedly increase the risk of some major climate tipping points is a compelling reason for the most decisive and urgent action to accelerate decarbonizing the global economy as we call it, but basically stopping fossil fuel burning completely globally and also stopping net land to use emissions of greenhouse gases as well.

Jason Mitchell:

It's interesting. Yeah, I tend to kind of look at these podcasts through this sort of the lens of one central question, which is what's at stake? And clearly there's a tremendous amount at stake. What does that mean in terms of our risk management protocol? Is it just wrong and if so, how do we improve it?

Tim Lenton:

Well, I think we have approached the climate problem the wrong way on several fronts. I think the climate science community have got to put their hands up partly on that as well as the border policy community. The first thing was that we weren't, in my view, really treating climate change as a risk management problem for a long time. I think that message has got through now, and we have realized it's the ultimate risk management problem. And you have to take a risk approach, you have to just embrace and deal with the uncertainty and really consider the likelihood of damaging events, how damaging are they going to be, how many people are exposed to those damages, and how vulnerable are people to the damages they're exposed to? And we're starting to get there on that front, but frankly we've got a lot of work to do still and mapping out the risks from the climate tipping points as well as other climate damages.

But I suppose now we've got hopefully into the right head space with the problem. You don't have to do exhaustive work to see how potentially big the risks are, at which point any sane risk manager would be kind of adopting a response equivalent to what we might think about colloquially as taking out a very strong insurance policy or in against climate change is a major risk. Or in another metaphor, the way I would think of it is if you're a road cyclist and you used to road cycling, but you going down a mountain side that you'd never been down before on a winding road in some trees, and you have absolutely no idea as you're coming towards a corner, how sharp along that corner is, what are you going to do? When are you going to apply the brakes pretty hard and go pretty cautiously unless you've got to come some kind of suicide packed? And that's the kind of response that the whole climate risk and climate tipping point risk ought to be listening and maybe is beginning to now.

Jason Mitchell:

Let's hope. You co-authored a recent paper in February this year that I found really interesting. It was titled Many Risky Feedback Loops Amplify the Need for Climate Action, which publishes an expanded list of feedback loops that include 20 physical feedback loops and 21 biological feedback loops. It builds on that original list in your highly cited 2008 proceedings of the National Academy of Science's paper, that was obviously very well circulated. What does the history of revision say about the improvements to the way we model feedback loops and understand the Earth's climate system?

Tim Lenton:

Well, what we've seen over time is the more we study the earth system, the more feedback loops we discover and find we need to try and quantify, and this recent paper is kind of an example of that. Now, the feedback loops don't all have to be of the amplifying kind. They could be of the damping kind and that could be good news, but unfortunately when we revise the list, we have a habit of discovering slightly more of the amplifying feedbacks that could be a cause of trouble than the damping feedbacks that could reduce trouble. And we also know that when you have a system like the Earth's climate, which we've known frankly since the 1980s is in the state of net amplifying feedback. If you just add a little bit more amplification when you've already got a fairly strong amplifier, the results are kind of a disproportionate extra response.

Like the case in an electrical circuit or the case of feedback that we know when you put the microphone too close to the speaker. Yeah, as I've said, what we've known for decades is in fact were it not for any feedbacks in the climate system. If we doubled the carbon dioxide level in the atmosphere, that key greenhouse gas, we'd only expect about one point two degrees of global warming. But what our models tell us is at the moment because there's amplifying feedback in the system, we expect at least three degrees C of warming if we double CO2 levels in the short term back amount of warming, and in the longer term maybe up to six degrees C in global warming. So that tells you we've already got a strong amplifier in place, and if we start discovering over time further little, even little amplifiers that add on to that strong amplification, we've really got trouble.

Jason Mitchell:

What are some of the more problematic new feedback loops that you've added in over the last 15 years that particularly were you?

Tim Lenton:

I'd say the most striking thing that climate scientists have... I'd say quietly discovered in the last 15 years because I don't think this has hit the general consciousness, is the space missions, satellite missions to look more carefully at the clouds particularly over the oceans and over the Souther Ocean, made a crucial discovery that the clouds, especially over the Southern Ocean, contain fewer ice crystals than we thought they did. So clouds could be made up of tiny water droplets or tiny ice crystals. In our models, we were assuming these Southern Ocean clouds were mostly ice crystals. And this was in the models crucial to a strong damping feedback in fact, which would be as you warm the world up and warm the clouds up, that ice crystals would turn towards a droplets and that affects the reflectivity of the clouds from space. It actually makes them more reflective.

So it's like a damping feedback on climate change, at least it would be if it were true that the clouds were for the ice crystals. Unfortunately, the satellite mission has told us they weren't, there was a lot less ice crystals and a lot more water droplets already in the clouds. And what that meant was models were wrong and they were wrong in a way that they had a strong damping feedback that shouldn't be there or could switch off under a modest amount of warming leaving us just with all the other amplifying feedbacks. And that particular discovery is crucial to the question of how much warmer it's going to get and the possibility that as we warm things up a little bit, we could kind of knock out this crucial damping feedback from clouds and just be left with the other amplifying feedbacks. And suddenly when we recalibrate our models, instead of them giving say a two or three degrees sea warming, they could jump to giving a five or six degrees sea warming when that feedback sort of switches off.

Jason Mitchell:

That's quite frightening. Does that mean it's an air in our climate models or a weakening in the warm to cold vertical air current?

Tim Lenton:

It's basically the process of science. It means, at least for some of our models, we had a flawed assumption about this case, the nature of the kind of physical state of some of the clouds. But in the spirit of science, we go out and we try to observe better the way the world is and then we try to make our models better accordingly. And unfortunately in this case we found out something that first several of the models suddenly made their climate sensitivity as it's called much higher. That's not necessarily the only thing we could discover. I mean, we also make discoveries that go in the other direction sometimes. So this is not the last word, but it's just the way we need to think about this is perhaps all the more reason to keep trying to understand the climate system better and keep improving our models with the help of improved observation. That's the process of science basically.

Jason Mitchell:

One of the interesting features that I mentioned of this paper is the inclusion of biological feedback mechanisms. Why do you think the science community has been relatively slow to examine the impact of biological feedback loops like forest dieback, permafrost thawing, and loss of soil carbon in climate models?

Tim Lenton:

There's a sort of history to how a climate model came about in the first place. They were really born out of where the forecasting models which were, of course, concerned principally with the physics of the weather and the water cycle. And on the short time scales of the weather, okay, it turns out you actually need some kind of decent representation of the land surface and it's physical properties like the fact that the trees return water to the atmosphere through opening the holes, the stomata in their leaves and so on.

But what you didn't need to do in a weather forecast model was get into all the detail of the carbon cycle, the cycling of methane nitrous oxide or the greenhouse gases by biology. So the fact that the climate model has its heritage in a weather forecast model, and what happened was basically bits got added on to the atmosphere like the ocean and then sorting out bits of land surface meant that the last thing we've kind of got to are the biosphere and its longer timescale processes and responses and also on a different front ice sheets, which are a really slow responding system.

So yeah, it's a sort of, here's part historical accident that we've been slow to get round to sort of properly looking at the biological feedbacks in the system. Although my great hero, Jim Lovelock of the Gaia Hypothesis Fame has been rightly telling us since the 1970s, if not before, that we really needed to be thinking about biological feedbacks in the system as crucial.

Jason Mitchell:

It's interesting, I even draw a parallel to the investment community where I find that investors tend to look very discreetly at climate apart from biodiversity issues, but let's hope that becomes more closely examined together.

Tim Lenton:

Precisely, Jason, but I think that investors like everybody else seek some kind of continuity and simplicity. The ones I talk to don't want to have to have a whole separate accounting system for biodiversity. They started worrying about carbon and climate. They want a way of bringing biology into the same framework, not having to yet have a second and a third framework and so on.

Jason Mitchell:

I was going to ask, how did these biological feedback loops compare to the big physical systems like ocean currents or a decline in sea ice? And also, if physical and biological feedback loops are increasingly coupled in climate models as we've just talked about, how do we couple them in real world decision making?

Tim Lenton:

Oh, yes. Well, on the first question, it depends what you're looking at, frankly, relative importance of the biological versus the physical and chemical feedbacks. But as you've hinted, really we start to see it as a couple system. So a crucial biological feedback that's a good one, is the fact that of all the CO2 we admits the atmosphere each year, a big chunk of it goes back into the land biosphere about just over a quarter typically. And then another quarter goes into the ocean through a mixture of sort of physics, chemistry, and biology frankly.

So the land sink is very much a biological one, and the ocean one is a part biological one. And without those damping feedbacks, the whole climate problem would be twice as bad already. So in that sense, the biosphere in the spirit of the guy hypothesis has been partly our savior up to now overall reducing change in the carbon cycle and hence the amount of climate change we're experiencing. Of course the big worries are, and there as we go forward, there is evidence that what has been a kind of overall damping feedback from the biosphere can weaken and ultimately potentially become an amplifying one.

Jason Mitchell:

What more does the paper reveal about the relationship between feedback loops and tipping points? You've warned about the risk of cascading tipping points where one tipping point triggers another. How has the science and empirical evidence around this cascading effect expanded over the last decade to point to demonstrable causal interactions? And where in your mind are the most obvious interactions of this? Is it for instance, the ice ocean albedo feedback?

Tim Lenton:

Well, and there's a lot to talk about there. So let me answer the key question about the risk of cascading feedbacks or tipping points. So first I need to say that feedbacks can be positive amplifying or damping negative in mathematical language, and of the feedbacks that are amplifying, it's only a subset that can get strong enough to cause a true tipping point where the amplification is so strong that you put one unit of change into the system, you go round the feedback loop and you get at least an additional unit of change that goes around the loop again, gives you another unit and so on. And that's self-propelling really strong amplifying feedback. But yeah, once we've established that some feedbacks can get that strong, at least within bits of the climate and we're going to call those and then potential climate tipping points. Then it turns out that when you tip any bits of the climate system, like you can tip the loss of the green and ice sheet or the West Antarctica sheet or a major change in the Atlantic overturning circulation of the ocean.

Well, that has consequences for other what I call tipping elements that have tipping points in the climate system. And sometimes it's such that tipping one thing makes tipping another more likely, and in the worst case, tipping ones that might make tipping another inevitable. And in last decade or so, we begin to piece together from a mixture of models, earth history and even observations, some worrying signs that there are these possible cascades of tipping one thing makes tipping another more likely if not inevitable.

And one of the cascades I could illustrate is starts potentially in the Arctic where we're seeing the whole region waring two or three times or four times faster than the global average because you're replacing a very reflective white sea ice surface that's melting away with a very dark ocean surface that absorbs a lot more heat, or that arctic warming also means kind of arctic moistening. It means it rains and snows more there, which is adding fresh water to the North Atlantic. It also means that amplified arctic warming, that the green and ice sheet is melting at an accelerating rate, and that's also a source of fresh meltwater into the North Atlantic Ocean.

And adding fresh water to the North Atlantic is a problem because it affects, it slows down and could ultimately collapse the great overturning circulation of the Atlantic Ocean, which depends on some waters that are coming northwards at the surface into the seas either side of Greenland. It depends on them getting those waters at the surface, getting cold enough but also salty enough and therefore dense enough to sink from the top of the ocean to the bottom on either side of Greenland. If you add salt fresh water into the surface waters of the ocean there, you make the water less dense, less prone to sinking.

And that's why you could break this fantasticly important circulation of the Atlantic Ocean, the overturn circulation. But that has its own knock on consequences because we know that in its normal state is bringing a huge amount of heat across the equator from the Southern Hemisphere it to the Northern Hemisphere, and it's dragging the rainfall band that's all the way around the tropics of the planet northwards. And that's effectively saying that it's key to the monsoons in West Africa, South America, India, around the planet.

So if you were to tip in this cascade a weakening or a collapse of the Atlantic overturn circulation, it would potentially seriously disrupt or tip monsoons in West Africa, India. And we're still trying to work out what it would do to the Amazon. And then finally, by breaking this ocean circulation, you would leave heat behind in the Southern Hemisphere, in the Southern Ocean, and heating of the water there is the crucial risk for the West Antarctica ice sheet and parts of the East Antarctica ice sheet. So you could increase the likelihood of tipping those eye sheets leading to many meters of sea level rise.

Jason Mitchell:

Yeah. I don't want to sound provocative, but it sounds like climate tipping points have essentially provided you a narrative about the sequence of a potential collapse of the earth climate system or at least one of its subsystems.

Tim Lenton:

Yeah. It's kind of presenting a potential narrative of how you would basically switch the climate into a recognizably different state. If anyone is present hundreds of thousands of years down the line to look back on this, they would probably see that as some kind of global tipping point. And the further you went into the future, the more the evidence would sort of get blurred and the more it would just like a global tipping point. But what I've spelled out is like the cascade that could be big enough to ultimately be kind of world changing.

Jason Mitchell:

Let's go back to the climate modeling line of thought. Can you talk about the climate modeling framework you're using to integrate tipping points. How does that compare to traditional IPCC climate models, which tend to be equilibrium climate sensitivity or ECS driven?

Tim Lenton:

Well, they do, but I've also worked with those models, and I'm actually in my group looking in those models to understand where do they show abrupt shifts and tipping points because they do show them increasingly. So there's a lot of positives to be said about the models, although they're always going to need improvement. But I wanted to also complement this sort of complex climate modeling approach with what could we learn about the possibility of tipping points directly from data. And to do that, we've been using something that's been well known for a while by mathematicians, but maybe not originally by climate folk, which is that in general, when a system is approaching a tipping point, it gives some telltale early morning signals. And they're a bit counterintuitive before you get to a tipping point where a small change makes a really big difference to a system, that system will actually become more sluggish and slow down in its ability to recover from little perturbations that they might be getting all the time.

So that phenomenon, which gets called critical slowing down, is a telltale sign that actually a tipping point might be approaching. What is actually happening in practice is you're seeing what now be called loss of resilience in the system, but we could also describe as the damping feedbacks that maintain stability in a system are getting weaker. And that's why a system will recover more slowly from middle shocks before it hits the point where amplifying feedbacks take over and you get a really big tipping point change.

Anyway, long story short, my group spent 10 or 15 years showing that these early warning signals can really exist for climate systems. They were there in Earth's past, before past about climate changes and they're there in models when you force a model towards a tipping point. You see the early warning signals beforehand. And now my group and others have started showing in real observational data that the classic early warning signals of loss of stability are present in bits of climate system that we think have the potential to exhibit tipping point, including the Amazon rainforest, the Great Atlantic overturning circulation I talked about. And also for example, part of the Greenland ice sheet.

Jason Mitchell:

Yeah, it's such a interesting part of this discussion. I mean, I was wondering what are the early warning systems for these tipping points? How are we monitoring them under even the Gaia 2.0 model? How do we know when we're there? And I'm wondering, can you put early warning systems into context maybe using a potential collapse of the Atlantic Meridian overturning circulation per year 2014 paper?

Tim Lenton:

Sure. So that great overturning circulation, as we've heard, is the big one to be worried about. We know it's tipped in the past, we know it could be a still tipping in the future. It's also something that sciences and governments are spending a lot of money and effort trying to monitor. And that includes in major investments in setting up kind of east to west transects they're called, but monitoring arrays at different latitudes in the Atlantic. The first one that got invested in is at about 26 degrees north, so kind of the boundary of the tropics and the subtropics, but more recently monitoring, it's been put in a raise going sort of west, east across part of the North Atlantic and also towards the southern boundary of the Atlantic, kind of like the bottom of Africa across to South America.

And what we had already worked out by kind of studying model worlds back and published back in 2014 was that you could get much better early warning signals at Atlantic overturning circulation tipping point at some latitudes of the ocean than others. In fact, the best signals would be up at the northern high latitude and at the southern boundary of the Atlantic.

So it's by chance more than by design. But happily, some of the more recent investment in actual monitoring is in useful places or arguably the most useful places to pick up the early warning signals in a possible tipping point ahead. And in a broader way to think about this, we crucially need to increase our sensing capacity of our life support system, the earth system or Gaia. And clearly one kind of sensing capacity is sensing the possibility that bits of the system could head towards damaging tipping points.

And this is just a specific example of how we can do that for a part of the ocean, but systematically we can also do that for the land biosphere. And we're increasingly in migrate using the satellite remote sensing data that's already available to do a kind of global, we would call it resilience sensing of the terrestrial biosphere, at least to see which bits might be losing stability. And that showed us than we published last year, that it showed us that the Amazon rainforest, it's showed a really strong signal of stability loss over the last 20 years. So yeah, there's more to do, but it just shows us that there's information to be getting down there by increasing assets and capacity of our life support system.

Jason Mitchell:

The IPCCs AR6 synthesis report, which came out last month seems to recognize the gravity of tipping points. In fact, the report states that quote risks associated with large scale singular events or tipping points such as iced sheet instability or ecosystem loss from tropical force transitioned to high risk between one point five to two and a half Degrees Celsius, and to very high risk between two and half to four degrees Celsius. How do you grade the IPCCs efforts in integrating tipping point effects like non-linear change into their climate modeling frameworks?

Tim Lenton:

Well, I was really pleased to see what you just quoted appearing in the recent synthesis report, and I think it's making a nod to the study republished in September last year, 2022, where we systematically looked across about 230 published studies on tipping points and pulled all that information and data together to give an updated assessment of climate tipping point risks. Which is pretty comparable to the statement that the IPCC came out with, although I'd probably be even more kind of risky in my statement in the sense that I think things look really bad above two degrees C and that there's quite a lot of trouble looking between one and a half and two degrees C.

But to answer the broader question, we've got a history in this kind of broad assessments that myself and others participate in at IPCCC are firing on the side of loose drama. And so now, I mean, risk is neatly put it, but we're starting to now stopped at doing that and give an honest risk assessment. And that includes a considerable change in the IPCCs assessment of tipping point risks over time. I mean, over the last 20 years, it's gone from a situation where 20 years ago the IPPC would be saying there's only really a significant risk of climate tipping points at four or five degrees C of global warming to the quote you just gave, which is the risks kicking up above one and a half degrees sea of global warming. So I think that's a welcome development in the sense of giving everybody on the planet as well as the policy makers, a more salient and honest risk assessment.

And I think as we carry on, I fear that we're just going to discover that these risks are even more real than we thought they were. You never know, we might have some positive news as we move ahead, but I think we're now in a better place in the overall assessment. We've got real, as it were, about tipping point risks. And what I'm hoping for is that there might be a special report on tipping points in the next, what's called Seventh Assessment Report cycle of IPCC. But that is far from clear, there's a lot of haggling politically over what should be the priority for special reports, but at least we can take some comfort that finally the kind of IPCC process is giving us, I think, a more accurate statement on these tipping point risks.

Jason Mitchell:

Well, that's good to hear. One of the fascinating aspects for me doing research for this podcast episode was trying to understand the arc of your work. And what I mean by that is that your focus on tipping points is widened from climate to include technological and policy tipping points. Did this expansion grow out of frustration of the constraints within the science community, or was it a more organic growth in confidence around the application of tipping points in the realm of social and environmental justice as sort of a way to drive change in wider behaviors?

Tim Lenton:

Yeah, good question. It's hard to know sometimes why your own mind does the things it does, but I think for me, I would give the credit back to my original passion, which was to study Gaia the earth system as a part living system. And all the work I did from with GENIE blocked from the early days, it made me acutely aware that we are biology, and like all biology, sometimes small innovations that start in some seemingly nondescript or tiny bit of the biosphere can sometimes, occasionally turn into large consequences. Thanks to feedbacks, networks effects, and the rest. So I was always kind of looking at us humans as just another species in Gaia.

And our technological innovations, as we've seen obviously in human history, can occasionally be world changing. I mean, think of the domestication of crops in the agricultural revolution or the innovations that drove the industrial revolution, and of course the reinforcing feedbacks that also made those things revolutions in the true sense of the world. They became abrupt and self propelling, certainly the industrial revolution, just as is the modern growth regime as economists call it, in the economy.

So I sensitized to all that. And so whilst it was alarming to be of course discovering potential bad tipping points in the biosphere in the climate, one, it was totally natural for me to also see the possibility for a tipping point in societies away from fossil fuel turning to renewables, a subdominant source of power and also other possible tipping points towards what's clearly called a more circular economy. And that these would have to stem originally from sort of quirky innovations that sort of nobody notices to begin with, but then gain their own momentum.

As we've been going through the beginning of this new millennium since about the year 2000, I began to sort of see in the evidence that some things that have been around since I was a kid, like solar panels, electric vehicles were coming. They were really starting as innovations to become more cost competitive. They were starting to scale up. They were starting to demonstrate their own amplifying feedbacks. And that's why I was looking at the same time at these what I'm now calling potential positive tipping points of abrupt social and technological change.

And you're right, I was also in a little bit of despair at the way we were all considering our ability to do anything about the climate problem. Along with all the kind of political gathering that's been going on. We seem to have a completely linear view of how it would be to try and tackle a climate problem and also a kind of wrong economic view that it was always going to be a net cost to do anything about climate change, which is kind of a council of despair, frankly. Whereas I firmly believe that now the evidence is clear that shifting abruptly to renewable power is a net saving in monetary terms and a net benefit for a huge number of reasons for society worldwide. So yeah, I've been motivated from a mixture of directions to want to shine a bit more of a light on the possibility of strong amplifying feedbacks and tipping points of the good kind accelerating changes that I feel normatively we need in society and technology.

Jason Mitchell:

Gaia 2.0 seems to represent a grand theory that unifies your work around planetary boundaries, tipping points in early warming systems. Where in your mind is receptivity for its stand, particularly this argument that humans need to add some level of self-awareness to Earth self-regulation?

Tim Lenton:

Well, I don't know whether too many people would contest that proposition, but I would've to say that the whole original notion of Gaia of life playing an integral role in a self-regulating earth system has remained a kind of subject among many scientists just because of ways that James Lovelock and Lynn Margulis originally phrased the hypothesis in the early 1970s. They made it seem what scientists and philosophers was called teleological, as if they were suggesting that life was all purposely kind of reshaping the planet for itself. And that's left the academics at least largely ignoring Gaia. And I suspect they wouldn't be too keen in general on my use of the term Gaia 2.0 to try and encapsulate my thinking that yes, as a self-aware and a collectively self-aware species, we could be finally the ones to bring a bit of theology, a bit of self-aware, self-regulation into the system.

So they would object to the name, but would they object to the concept? I don't think so because we're all in the field effectively working on how on earth can we do something about climate change. And I think in the politics of this, as my late dear friend Bruno Latour put it, the fact that we're so vexed about climate change and we are talking about targets like one and a half or two degrees C, and desperately wanting to get action to meet them, tells us that we all instinctively almost recognized that we were living in a regulated system or climate system. And that has been knocked out of whack as able to put it.

So we might object to the phrase glare, and certainly some academics do, but actually conceptually, I think we're all on board with the basic idea that we recognize we are acting collectively in a way that's messing up our own life support system. This is not a smart way to proceed, and therefore we need to use that collective self-awareness to try and get to a better place, to sense where things are going wrong better and get better at correcting our mistakes. And if you're more optimistic like me, get to a place where we have a vision of a better future we want to work towards, and we believe we can work with our feedback loops that we are creating and strengthening to propel change towards that desirable place.

Jason Mitchell:

Well, what are examples of how this human self-awareness can manifest this ability, this agency, at least in theory, I would imagine carbon markets are a potential way into the earth system where we trade flows of CO2 in and out of the atmosphere. Obviously there are a lot of critics, but how do you see markets playing a role here, and are there other ways aside from carbon systems like Net Zero strategies?

Tim Lenton:

There's certainly many ways that we could be bringing this collective self-awareness to bear. I mean, I often think about it in myself and how my own actions would perhaps that I felt compelled to change them because of what I knew about the consequences of my own activities like flying. So I managed not to fly for a long time, for example, also change how I eat and things like that. But it's perhaps one shouldn't overemphasize solely individual action here because as you write the hint, it's about a mixture of the bottom up individual changes we can make and the sort of top down changes we can also make to try and stimulate change in the right direction.

And on those more top down mechanisms, well, we can indeed try to put a sensible price on the pollution, the carbon pollution that's causing the problem. What we would learn there is that you don't want the same carbon price in all parts of the economy. That's not the most effective way to create change. As the UK has beautifully proven, you only need a fairly modest price on carbon emissions in the power sector, electricity generation, basically, to fundamentally tip positive change. We've shut coal burning out per generation in just the last 10 years with the modest carbon price.

We'll need a lot higher price on carbon for cement making or steel manufacture for that to be the best lever. And more generally, I would say what recent history teaches us is it's more effective to incentivize the new green technologies. So to spend public money on everything from early research and development to introducing kind of green tariffs and other incentive schemes, that's generally has a role even more effective than punitively, taxing the bad pollution, the CO2, but probably using both and is even, he's even the most effective approach when done in the smart way. So yeah, putting proper pricing into the marketplace helps, but also how public money is deployed can really help. And we see that with initiatives like the Inflation Reduction Act in the US and the big stimulus package there for green innovation and technology coming to scale.

Jason Mitchell:

Well, great. So it's been fascinating to discuss what's at stake when we talk about planetary boundaries, early warning systems, and climate tipping points, how the supporting science and empirical evidence have expanded over the last decade, and why Gaia 2.0 represents a powerful framework to reinforce global sustainability. So I'd really like to thank you for your time and insights. I'm Jason Mitchell, head of Responsible Investment Research at Man Group, here today with Tim Lenton, professor of Climate Change and Earth System Science at the University of Exeter, and director of the Global Systems Institute. Many thanks for joining us on a sustainable future, and I hope you'll join us on our next podcast episode. Thank you so much, Tim.

Tim Lenton:

Thank you, Jason.


What are 3 types of tipping points for Earth's climate? ›

Tipping elements
Proposed climate tipping element (and tipping point)Threshold ( °C)Timescale (years)
Boreal Permafrost (abrupt thaw)1.5200
Barents Sea Ice (abrupt loss)1.625
Mountain Glaciers (loss)2.0200
4 more rows

What are the 9 climate tipping points? ›

At more than 2o C, the nine global tipping points identified are the collapse of Greenland, West Antarctic, and two parts of the east Antarctic ice sheets, the partial and total collapse of Atlantic Meridional Overturning Circulation (AMOC), Amazon dieback, permafrost collapse and winter sea ice loss in the Arctic.

What is the tipping point of the IPCC? ›

The Intergovernmental Panel on Climate Change (IPCC) defines tipping points as “critical thresholds in a system that, when exceeded, can lead to a significant change in the state of the system, often with an understanding that the change is irreversible.”

How close are we to climate tipping points? ›

Most recently, a study published in Science concluded that we may have already crossed some tipping point thresholds with the 1.1 degrees Celsius of global warming that humans have caused so far. More will become likely if we surpass the 1.5-degree threshold.

What are the 7 tipping points? ›

The nine global tipping points identified are: the collapse of the Greenland, west Antarctic and two parts of the east Antarctic ice sheets, the partial and total collapse of Amoc, Amazon dieback, permafrost collapse and winter sea ice loss in the Arctic.

What are two examples of key tipping points in the Earth system? ›

Tipping Point Examples
  • Melting sea ice: retreating Arctic and Antarctic glaciers may not be able to recover once temperatures are too high.
  • Slowing ocean currents: freshwater from melting ice sheets will slow currents down, so these tipping points are intrinsically linked.

Are climate tipping points real? ›

For the set of likely future scenarios we face today, the climate science literature has not identified any approaching global tipping point after which runaway climate change intensifies beyond humanity's ability to arrest it.

What are the main lessons of the tipping point? ›

1-Sentence-Summary: The Tipping Point explains how ideas spread like epidemics and which few elements need to come together to help an idea reach the point of critical mass, where its viral effect becomes unstoppable.

How long until global warming is irreversible? ›

time is really running out very, very fast”. Emissions must fall by about half by 2030 to meet the internationally agreed target of 1.5C of heating but are still rising, the reports showed – at a time when oil giants are making astronomical amounts of money.

Will climate change become irreversible? ›

While the effects of human activities on Earth's climate to date are irreversible on the timescale of humans alive today, every little bit of avoided future temperature increases results in less warming that would otherwise persist for essentially forever.

Is there still a chance for us to lower the possibility of reaching the tipping point if yes what should we do? ›

Keeping global warming below 1.5C would significantly reduce the risk of reaching these dangerous tipping points in the near future. To have a 50 per cent chance of doing this, global greenhouse gas emissions must be cut in half by 2030 and net-zero reached by 2050.

What happens if we exceed 1.5 degrees? ›

Scientists say that surpassing 1.5 degrees C could trigger a cascade of tipping points, which would irreversibly alter the global climate system and further exacerbate warming.

What is an example of a tipping point? ›

Tip the glass a little further, and still not much happens — the milk just sloshes in the glass. But, tip the glass far enough, and the milk will suddenly pour out onto the table. This moment of suddenly changing from one state (milk in glass, dry table) to another state (milk on table) is called a tipping point.

What is the 1.5 tipping point? ›

The 1.5 degrees Celsius threshold became prominent in 2010, and it has since been considered the upper limit of warming Earth can endure before the effects, specifically those of triggered tipping points, become irreversible.

What are the three rules of the tipping point? ›

Comprehending the tipping point and its role in social epidemics involves understanding three “rules”: the law of the few, the stickiness factor, and the power of context. Gladwell contends that creating an epidemic involves a few agents of change or influential people to deliver the message.

What is considered to be a silver bullet for climate change? ›

There are two silver bullets for ending climate change.

Limestone (example, The White Cliffs of Dover). From organism shells over millions of years. 99.9% of Earth's carbon is held in limestone deposited on the seafloor. Ocean Photosynthesis (example, Phytoplankton, algae, and fish) corresponds to iron availability.

What is 10 percent tipping point? ›

10% of a Population

Scientists at Rensselaer Polytechnic Institute have found that when just 10% of the population holds an unshakable belief, their belief will always be adopted by the majority of people who simply change their beliefs if their last two social interactions agreed with a new one.

What are five possible inputs of Earth as a system? ›

The five systems of Earth (geosphere, biosphere, cryosphere, hydrosphere, and atmosphere) interact to produce the environments we are familiar with.

What is the tipping point of the ecosystem? ›

Tipping points are a point at which an ecosystem can no longer cope with environmental change, and the ecosystem suddenly shifts from one state to another. These shifts are almost always negative – for example the loss of resources such as biodiversity and kai moana, or ecosystem services such as water purification.

What is a climate change tipping point quizlet? ›

climate tipping point. Point at which an environmental problem reaches a threshold level where scientists fear it could cause irreversible climate disruption.

Why are tipping points uncertain? ›

Why are tipping points uncertain? Scientists have no way of knowing what the tipping point would be until we pass it. Select the reasons why global warming might still occur even if greenhouse-gas emissions drastically decrease.

Which of the following is not a tipping point for climate change? ›

Instant Text Answer. 5. Increased use of public transportation In this list, "Increased use of public transportation" is not a tipping point for climate change. Instead, it is a potential solution to reduce greenhouse gas emissions and mitigate climate change.

What is Gladwell's thesis in tipping point? ›

Gladwell's thesis is that social phenomena are driven past the tipping point by the subtle workings of a tiny subset of the population. Individuals with special social characteristics or employing certain seemingly unimportant techniques can make a huge difference.

What is the conclusion of the book the tipping point? ›

The biggest lesson of all about the Tipping Point is simply that the world is not immovable. Tiny “pushes,” if done the right way, can change the world. In the end, Gladwell's message is neither entirely optimistic nor pessimistic. For better or worse, small changes can have a major influence on the world.

Is it tipping point or breaking point? ›

A breaking point is some major event that finally is the proverbial straw that breaks the “camel's back.” Others seek help after finally reaching a tipping point, or a series of events that lead up to that self-reflective “ah-ha moment” that something is just not right and a change needs to be made.

What are planetary boundaries for dummies? ›

Planetary boundaries are a framework to describe limits to the impacts of human activities on the Earth system. Beyond these limits, the environment may not be able to self-regulate anymore. This would mean the Earth system would leave the period of stability of the Holocene, in which human society developed.

How soon will the planetary boundaries be exceeded? ›

There has been a 50-fold increase in the production of chemicals since 1950. This is projected to triple again by 2050. Researchers conclude planetary boundary has now been exceeded, raising the risks to the stability of the Earth system.

How bad will global warming be in 2030? ›

It says that global average temperatures are estimated to rise 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial levels sometime around “the first half of the 2030s,” as humans continue to burn coal, oil and natural gas.

How long do humans have left? ›

And while the starting point for modern humans is also up for debate, if we say that we've already been around for 200,000 years, we have a fairly comfortable minimum of 800,000 years left – a figure that's again in line with Gott's predictions.

How many years do we have left on earth? ›

Our planet's history will end as it enters the scorching outer layers of its parent star. If you take comfort in the thought that life has another five billion years ahead of it before the Earth ends, don't. Five billion years is how long the planet has left.

What is the final warning for climate change? ›

According to the IPCC report, limiting global warming to 1.5°C requires a peak before 2025, reduce emissions by 43% by 2030, 60% by 2035 and reach net-zero in early 2050.

Is global warming going to get better or worse? ›

Is climate change getting better or worse? If greenhouse gas emissions are increasing — which they are, according to NPR — then technically, climate change is getting worse.

Is it too late to save the planet? ›

The August 2021 report released by the Intergovernmental Panel on Climate Change (IPCC) confirmed that there's no chance of undoing the damage already caused by global warming, with climate scientist Linda Mearns stating: “It's just guaranteed that it's going to get worse.

What would happen if Amazon reaches tipping point? ›

With enough time and forest losses, scientists say, large swaths of the Amazon could fall into an unstoppable spiral that would transform them from lush rainforest into grassy savanna. The global implications would be profound. The loss of the rainforest would cause a large-scale drying across the region.

Who keeps the money on tipping point? ›

The contestants who don't make it to the Final still take home the money they have accumulated for their chosen charities and even if a contestant is eliminated with a total of £0, a donation is still made to their charity.

What happens when the Amazon reaches its tipping point? ›

Scientists warn that the Amazon is approaching a tipping point beyond which it would begin to transition from a lush tropical forest into a dry, degraded savanna. This point may be reached when 25% of the forest is lost.

What happens if the Earth warms 2 degrees? ›

If warming reaches 2 degrees Celsius, more than 70 percent of Earth's coastlines will see sea-level rise greater than 0.66 feet (0.2 meters), resulting in increased coastal flooding, beach erosion, salinization of water supplies and other impacts on humans and ecological systems.

Was the Earth warmer 12000 years ago than today? ›

The planetary change that accompanied that warming is mind-boggling: 12,000 years ago, most of North America was 36 degrees colder than it is today, largely because of the retreating ice sheets.

Will 1.5 degrees happen by 2030 or 2050? ›

The study, published Jan. 30 in Proceedings of the National Academy of Sciences, provides new evidence that global warming is on track to reach 1.5 degrees Celsius (2.7 Fahrenheit) above pre-industrial averages in the early 2030s, regardless of how much greenhouse gas emissions rise or fall in the coming decade.

Is tipping point positive or negative? ›

Tipping points occur when a positive feedback loop crosses a threshold that leads to large changes, that often can't be turned around or reversed.

Why is Antarctica considered a major tipping point? ›

Losses of portions of the Antarctic ice sheet are believed to already have passed the tipping point. This means that these ice sheet losses are now occurring at a rate where they cannot be reversed. The continuing losses of the Antarctic ice sheet also means an ongoing rise in sea levels over the coming centuries.

Can the Earth reach a tipping point if it keeps warming? ›

Out of those, one regional and three global climate elements are estimated to likely pass a tipping point if global warming reaches 1.5 °C (2.7 °F), namely Greenland ice sheet collapse, West Antarctic ice sheet collapse, tropical coral reef die off, and boreal permafrost abrupt thaw.

What are the three characteristics of a tipping point? ›

The writer Malcolm Gladwell outlines three characteristics of tipping points, which he calls “epidemics in action." Tipping points are characterized by 1) contagious behavior, 2) little actions having big effects, and 3) changes happening in a hurry (rather than slowly and over time).

What are three other major factors that influence climate 3 points? ›

The temperature characteristics of a region are influenced by natural factors such as latitude, elevation and the presence of ocean currents.

What are tipping points in geography? ›

A climate tipping point is a critical threshold when global or regional climate changes from one stable state to another stable state. The tipping point event may or may not be reversible.

What are tipping points in nature? ›

Climate tipping points are conditions beyond which changes in a part of the climate system become self-perpetuating. These changes may lead to abrupt, irreversible, and dangerous impacts with serious implications for humanity.

What are some examples of positive tipping points? ›

Examples of positive tipping points in recent history are the abolition of slavery, the end child labour and the implementation of universal rights to education and political participation for women and minority groups.

What are examples of tipping elements? ›

Examples of tipping elements are the Amazon rainforest or the Arctic ice. If the temperature on Earth rises, these systems will be severely affected when a certain temperature is reached - the tipping point. We use the word 'tipping' because these changes cannot be reversed once they occur.

What is a tipping point example? ›

Tip the glass a little further, and still not much happens — the milk just sloshes in the glass. But, tip the glass far enough, and the milk will suddenly pour out onto the table. This moment of suddenly changing from one state (milk in glass, dry table) to another state (milk on table) is called a tipping point.

What are the 2 biggest factors in determining climate? ›

The two most important factors in the climate of an area are temperature and precipitation. The yearly average temperature of the area is obviously important, but the yearly range in temperature is also important.

What are 3 natural factors that can cause climate to change? ›

These have been caused by many natural factors, including changes in the sun, emissions from volcanoes, variations in Earth's orbit and levels of carbon dioxide (CO2).

What are the 4 things that determine climate? ›

A climate is the average yearly conditions of temperature, precipitation, winds, and clouds in an area.

Why is it called the tipping point? ›

The phrase was first used in sociology by Morton Grodzins when he adopted the phrase from physics where it referred to the adding a small amount of weight to a balanced object until the additional weight caused the object to suddenly and completely topple, or tip.

Is the climate tipping point real? ›

For the set of likely future scenarios we face today, the climate science literature has not identified any approaching global tipping point after which runaway climate change intensifies beyond humanity's ability to arrest it.

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