Ep49: Johan Rockström 'Pushing Planetary Boundaries'

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Michael Liebreich: Before we start, if you're enjoying these conversations, please make sure that you like or subscribe to Cleaning Up, it really helps other people to find us. Cleaning Up is brought to you by the Liebreich Foundation and the Gilardini Foundation. Hello, my name is Michael Liebreich, and this is Cleaning Up. My guest today is Johan Rockström. He's the director of the Potsdam Institute for Climate Impact Research, he's a professor of Earth System Science, and he's the originator of the Planetary Boundaries Framework, which looks at the stable area for the Earth's geophysical systems. He and David Attenborough have just got a documentary called Breaking Boundaries on Netflix. Let's bring Professor Rockström into the conversation. So, Johan, welcome to Cleaning Up. You must be a busy, busy guy with your new Netflix documentary out recently.

Johan Rockström: Yeah, it's fantastic to see that it's getting the momentum. We were hoping for, of course having said David Attenborough on your side with a narrative helps.

ML: That's right. Tell us a little bit about the documentary because, you know, I have just finished watching it. But others may not have even heard about it, potentially, amongst we've got quite a diverse audience here. So, it's called Breaking Boundaries. What does it try to do?

JR: You know, the working title for it before Netflix came up with this great title was The Best Untold Story in Town. And I think that basically tells a bit more what it is because it really is, for the first time, to try and tell the story of how we, as humanity, now impact the entire planet, we determine its outcome, we're sitting in the driving seat, and how do we navigate the Anthropocene, the new geological epoch, we're in to avoid crossing tipping points, but at the same time, transitioning in this exponential journey back to a safe operating space within planetary boundaries that gives us a safe landing and much, much more attractive outcomes. It's like an action movie or avoiding disaster outcomes a solution, the sun rises and rises and off we go towards a harmonious future. But it's all embedded, actually, for the first time that documentary summarizes the state of science on how do we manage the entire planet, all the planetary boundaries, not only climate, not only biodiversity, but all the systems that we depend on for the stability of the planet.

ML: But you set this up with this one extraordinary chart, this very long-term temperature chart, which shows how unusual the last sort of 8, 10, 12,000 years has been in terms of stability.

JR: You know, the Planetary Boundary Framework, which is at the heart of the Breaking Boundaries documentary, you know, emerges from 30 years of extraordinary scientific advancement. And it's the advancement from the ice core science, showing how, you know, the planet has been oscillating over the past 1 million years, in and out of deep, deep ice ages for 100,000 years, and then into shorter 15,000 yearlong interglacials, and back into ice ages, out into these interglacials. We have six to eight such cycles of last one million years, they follow a very predictable cycle called the Milankovitch cycles, which have been determined by basically the orbit of planet Earth around the Sun. So, it's about solar forcing. And then, you know, we humans, Homo Sapiens, we modern humans, have only been around on planet Earth for roughly the two final cycles the last 200,000 years. So, we've only been here for two cycles. And we've been hunters and gatherers, a few million people during basically the entirety of that period. So, to put it simple, we've had a very rough time as humans living largely in ice age deep ice age, and then we'll leave this last Ice Age 20,000 years ago. And it's a minus four degree Celsius world where we're in deep Ice Age, the sea levels are, you know, 50, 60 metres lower than today. We have very few pockets on Earth where we can have a really good livelihood, we leave the last ice age, and then we land in this final interglacial, the one we call the Holocene, and it's the last 12,000 years. And it's an extraordinarily stable state because it's a warm interglacial, that with a global mean temperature varying just plus or minus one degrees Celsius. And it's at that point that we shift from being hunters and gatherers to inventing agriculture and we become farmers, and we start the civilizational journey as we know it. And we have, you know, significant scientific evidence today that is, thanks to the stability, that we're able to shift from hunters and gatherers to farmers, and develop civilizations as we know it, meaning that our modern world depends on the Holocene. And that insight, that very insight is of course, a key entry point towards then defining what does it take to keep the planet there? And there you have the planetary boundary framework in a nutshell, basically.

ML: Right, and so the rest of not just a documentary, but also your life, work both in Stockholm, the Resilience Institute, and then in Potsdam, has been about how do we stay in that, it's no longer the Holocene it’s the Anthropocene because we're having such a huge impact as humans. So, it's kind of hard to keep it there. But if I could, how did we get there? Why did you get this kind of wild fluctuation that suddenly just kind of flatlines in the Goldilocks zone?

JR: Yeah, so well, to start with one, one should be clear that scientifically, we don't have the exact answer on that. So the jury's still out. What makes the Holocene so extraordinarily stable? My conclusion today is that the stability of the Holocene is basically a serendipitous outcome of the physics surrounding Planet Earth, the combination of solar activity being within a certain limited range, the orbital forcing from the sun being within a narrow range, and that we have, you know, over the past 3 million years, actually gradually seenhow the variability, the natural variability of the pressures on the planet had been gradually slowing down. So, we have less volcanic eruptions, less earthquakes, less kind of big magnifying events. So, what we end up with is a planet that is gradually basically settling down, if we put it that way, the universe around us that is giving us you know, some variability definitely but not outside, basically a coping range for the planet. And the combination with a very resilient Earth system, resilient in terms of capacity to dampen and buffer carbon dioxide uptake in the oceans, heat uptake in the oceans, carbon uptake on natural ecosystems, albedo reflections on ice sheets, all these functions being at a very, you know, high level, combined with this limited that gives us a relatively stable state in the Holocene, other scientists even come up with a hypothesis that could it be that that we humans, having started to exploit Planet Earth, you know, at the beginning of the Holocene could our transformation towards more agricultural land and deforestation have basically contributed towards a less variable state of the system. I doubt it. But it's just a flag that that assessment is still not conclusive. But be that as it may, we know that we enter the Holocene, and we have this very narrow corridor of a plus/minus one degree Celsius variability. And then all the way up to the mid 1950s we stay within this corridor that is in the 1950s, that would take off, and what we now call the great acceleration, which is the hockey sticks of exponential growth, which starts only 70 years ago, you know, carbon dioxide, deforestation, pollution, all the nitrogen, phosphorus, exploiting basically all the functions in your system. So, it's not until the mid 1950s that we reach this takeoff point. And the interesting thing is that we go into 1960s, 70s, we get the first warnings with the Club of Rome, the limits to growth and Rachel Carson and Silent Spring, but still, the earth system is so resilient, that all the pressures are essentially being buffered. Everything from air pollutants, overfishing, the loss of biodiversity to atmospheric greenhouse gas concentrations, it's all buffered because the planet seems biogeochemically determined to stay in the Holocene. And it's not until we passed 1990 that we start seeing the invoices being sent back. This is where we start seeing, you know, collapse of fisheries, collapsing lake system, collapse of ecosystems, accelerated ice melt, we start seeing shifts that are more significant and that's why I conclude and a few other person scientists disagree with me, but this, again is at the scientific frontier, that it's not until we reach the 1990s that we can talk about a saturation point that we're starting to hit the ceiling of the hardwired biogeochemical processes and systems that regulates the state of the planet. And it's not until then that we have all the sudden Is that okay, the Holocene is the state that we depend on. We've entered the Anthropocene, which is from the 1950s with this acceleration points. And finally, from 1990 onwards, we start seeing one more evidence of these nonlinear changes and tipping point behaviour that rain forest can shift over to savanna system, that systems can flip. And you put all that together, you of course, need to start defining what's the safe fence? What are the boundaries, that can keep the system intact? As you say, we depend on the Holocene or we're now in the Anthropocene, and this can be quite confusing for many. And it is and I try always to sort this out by explaining that. Yes, we've left the Holocene. We are in a new geological epoch, the Anthropocene. However, as you hinted, the Holocene is an equilibrium state, is an interglacial state of the planet. the Anthropocene is not yet a new state. We haven't drifted away from the interglacial into some hothouse Earth state, we're still in an Holocene equilibrium state. The Anthropocene so far is only a pressure. It's not a new state. So our biggest task, in my view, I mean, humanity's biggest task is to avoid that the Anthropocene shifts from pressure to state, because being a state means that it self-reinforces into a new equilibrium, and that new equilibrium would be a hot planet without ice sheets far out in terms of temperatures and life conditions on Earth so that that's why the window I would conclude is still open for us to remain and what we a bit nerdily scientists call a Holocene-like state so we cannot go back to the virgin Holocene, but we can at least manage within a state that resembles the Holocene.

ML: Okay, so there's a lot there to unpack and, and I want to sort of go back to this business of the Holocene being so stable. What you're talking about is avoiding kicking it back into what you saw at the end, you said, Well, we've got another state, which would be a hothouse Earth, but really, we don't know whether that's whether there is another stable state, that's hothouse Earth, we couldn't kick it back into this kind of turbulent behaviour. Because you know, it does, it is absolutely striking in that chart that it used to be like this, and then it goes flat. So engineers would easily recognize this as a sort of transition almost like a turbulent or laminar transition. But what you're saying is, we mustn't go to a hothouse Earth, which would be another sort of laminar condition, but a worse one. But isn't it also, you know, equally likely that we might go back to some kind of bouncing round, some kind of turbulence?

JR: And well, I would answer yes and no to that question, because you're absolutely right, that we could definitely foresee, envisage a future with, with oscillations around a very, very large and wide variability that we would go in to a new basically, turbulent phase. Definitely. However, there is no science today that suggests or there's no evidence that would support that that could occur at a lower temperature level. In fact, there are even scientific papers now showing that we may, because of our burning of fossil fuels have shut the door to the next Ice Age. So normally, if we humans had not been around burning fossil fuels and cutting down forests and emitting all of these greenhouse gases, we would normally at some point in 10,000-15,000 years roughly start going back into the next Ice Age. That would be the normal Milankovitch fluctuation given our orbit around the sun. We have very likely, I even say very likely, due to the climate forcing we've caused created the conditions that even if the sun cools down with the little fractional level it requires to enter new Ice Age, we have probably loaded so much heat to the system that we won't cross that threshold. So, the only future, we have only two options into the future. Either we're able to remain in an interglacial, a bit more oscillating, I would foresee, or we start drifting towards a warmer state. And that would not be a sudden, abrupt shift, and then we land somewhere else. It would be very jumpy, but it would be drifting, let's say, infinitely, because we would have very difficult to see turnaround there. But going back down into a very fluctuating cold state is very unlikely.

ML: I guess it’s partly to explore the different states we could end up in, and thanks for those sorts of those different options there, the menu that we've got, if you like, but I'm also hinting it, we've got a lot of uncertainties still. And we don't know why we went into that. There's still some you know, there's lack of knowledge about why we went into the Holocene, then there are also big uncertainties about where we might end up if we leave the Holocene slash Holocene-like Anthropocene, correct?

JR: No, you're right. And just to add to the uncertainty, something that very few people think about, because if you look at the planet, okay, so the planet has been around for 4.5 billion years. But if you look carefully at the record, and I know that many geologists disagree with me here, but if you look carefully, at the record, it's only in the past 3 million years, 3 million years in the Quaternary Period, that we've had a planet that I would argue is the only planet that really resembles our own today, the only planet that really matters for us. It's the only planet where we've had, you know, the continental configuration, the cycles of water, carbon, nitrogen, phosphorus, the element cycles, the atmosphere, the chemical physical composition that resembles anything similar to our planet today, go earlier than the Quaternary. And you enter the Miocene, the Pliocene, and then go even deeper into geological history when you come, you know, to a planet that has a completely different composition, both physically and chemically. So I would say it's only the last 3 million years that matter. If you look at those 3 million years, what is the corridor then? Well, the corridor, believe it or not, but the corridor is maximum heat, the warmest temperature on earth over the only period that matters for Planet Earth is two, we've not passed two degrees Celsius, according to the latest climate modelling over the past entire quaternary. This is Pleistocene plus Holocene. So of course, crashing through two degrees, means we're out in uncharted water, we have absolutely no reference point. When some scientists claim that well, you know, the last time we had four degrees Celsius warming was like 5 million years ago, we were in the Miocene, Pliocene periods, and of course, that could be a reference point, I say, careful here. Because then we had, you know, basically a different atmosphere, we have a completely different composition of continents, we got a completely different physical function in the ocean. So, it's a completely different beast. So, you're right, that we have different that's why it's so much scientific uncertainty around… So, to summarize, I mean, we have basically three known states of the planet, which we are well configured with, we know that there's a snowball Earth, the last time we had that was almost like 100 million years ago, so outside of the of the relevant reference point, and then we have ice age. And the ice age is a planet that has two permanent ice caps, you know, climbing down roughly to where I'm sitting right now in Berlin, basically. And it's 70 metres lower sea level on earth. And it's self-cooling, because the whiter gets the more heated reflects back into space. So, it becomes a self-reinforcing feedback. And it gets colder and it lands in this glacial ice state. And then you have interglacial and interglacial is that is a transient you’re right you could call it a… many call it a quasi-equilibrium because it's like that the semi state between ice ages, and then you have a hothouse. And the last time we had a hothouse was… the last time was 66 million years ago. So, you know, it's quite a long time back. And it's not the planet that has any reference really, to our current planet. So, we don't really know. But we're seeing the signs of how we seem to be passing through a point where self-cooling feedback shift to self-warming feedbacks, and that that is what makes us finding more and more evidence that we could we could drift off in that direction.

ML: Okay, but this is, this is sort of fundamental to your, your quest, which is to sort of to find the edges of the room, but you don't want to touch them. And so you're looking for these boundaries. You're looking for early warnings on the boundaries. But inherently, we don't know where those boundaries really are. And that is, where we're going with this is these become very difficult questions for societies to deal with. Because they like, people like certainties. They like to know that you can do two degrees, but you can't do you know, the orthodoxy was, a decade ago, two degrees was the tipping point. And now effectively, it has shifted in the last three, four years since Paris and since the IPCC’s one and a half degrees report, now, the orthodoxy is one and a half degrees is the tipping point. But actually, we don't really know, do we?

JR: No, you're right, we don't really know, I would not want to correct your statements. But just to put some more kind of, you know, explanation behind that. Because to begin with, I think there are very few scientists and I'm not among them, suggesting that 1.5 is a tipping point threshold. I think most science exploring the risk of tipping points, tipping points being when a system like the Greenland ice sheet, or the Amazon rainforest, or the overturning of heat in the in the North Atlantic shifts from one set of feedbacks that keeps that in the state we know, today, and it crosses a tipping point, and the feedback changes direction, and it's self-enforced in a new direction. So, rainforest shifts over to a savannah state, and icesheet turns to be ice free state and so on. Now, the science today shows that reach two degrees, and we are at risk of triggering tipping points. Not that the planet would tip but we are at risk of triggering a significant number of tipping point at 1.5, it's rather than the mainstream of science is that we will feel big impacts, we will have a lot of damage. Damage in terms of disease, heat waves, floods, droughts, invasive species, sea level rise, I mean, all the difficult to handle impacts will start getting there, there is science to show that three tipping points may be at risk already at 1.5. And as the Arctic sea ice, tropical coral reefs and West Antarctic ice shelves, those are the three that are being scientifically on the on the charts today. But I would say that 1.5 remains a kind of a high impact point, hitting the low-lying island states and low coastal zones of Bangladesh and an increasing heatwaves around the world for two degrees, even though we don't have the right we do not know for certain, but past two degrees and we see more and more indication that that might be you know, points, where were some of these tipping points, like the big ones, I mean, like the Amazon rainforest, or the Atlantic, overturning of the heat, or the larger parts of Greenland may cross tipping points. But you know, the uncertainty range is huge. Still, you're absolutely right. I get particularly concerned because looking at the entire Quaternary because we have never been beyond two, I think it's also a question of risk management. So, despite the uncertainty, the question is, what approach do you want to take in society: we want to optimise and take high risk or do we want to have precaution and try to play safe? And to me 1.5 is part of playing it safe for the Earth system. So, it is about reducing impacts, but also playing safe 1.5. You optimize around two, you take higher risk, because then we may be very close to triggering tipping point. And but you are actually right that that the journey from pre-Paris to post-Paris has been that pre-Paris we thought that two degrees was that precautionary point. And today we recognise that the cautionary point to be 1.5. But I would quite strongly argue that the journey from two to 1.5 is based on the advancements of science, I mean that there's a lot of, you know, I myself quite surprised despite working on this every day, how we have underestimated the pace of change. And change is happening faster than we have predicted. And that comes from everything from permafrost thawing ice melt, to coral reef damage, to forests die back, to West Antarctica, Antarctica in general, is melting faster at lower temperatures than we had predicted. So, there's of course a movement also in the advancements of science.

ML: Okay, so I want to just probe on one thing, ask for an explanation, clarification on one thing, I understand your definition of the tipping point is when a system, which operated one way gets into a regime where it reverses - the examples you've given Arctic ice, which reflects a lot of sunlight and heat, and then if it's gone, it becomes darker so it then becomes an absorbent and you named a few others, the Amazon rainforest presumably is now it's absorbing carbon, but it could flip into a zone where it's releasing carbon. But a lot of people interpret tipping points at the sort of planetary level that this is where we get out of that Holocene or Holocene-like environment and we spiral off to hothouse Earth. So when you say we may already have passed three tipping points, a lot of people would say, it's therefore we're, we're in, you know, real and substantial trouble today, not just that those three systems have gone, but that the whole planet has therefore flipped.

JR: Yeah, you know, I see that that is a misconception. And it's a very serious misconception. And we scientists carry a big responsibility in not spreading the wrong messages there. You're absolutely right. And this is, this is one more example of why we citizens in the world need to actually be well trained on these questions, because it is complex. And you know, the Earth system, the planet, our planet, our home, you want to know about your home. And our home is a complex, self-adaptive system, where not only do we have all these tipping points, they interact. And it's important to understand that it's not like one system tipping, it is a myriad of different systems interacting. And if you have two lakes that flip, so what? If you have 10,000 lakes that flip simultaneously? Well, then it could impact on the overall nitrogen budget, which in turn impacts on the climate system, which in turn impacts on rainfall, which in turn could cause droughts? So, you need to somehow have a feeling for this. But you're absolutely right, that nobody is suggesting that there is a planetary tipping point out there that causes runaway climate change. But what we are seeing is, I mean, just to give you the latest science there, just before the pandemic we're talking end of 2019, we published a 10-year update on the assessment of tipping points in the climate system. The first scientific publications was published in 2008, led by Tim Lenton et al., and 10 years later, 2018 we started working on a 10 year update. And we found that nine out of the known 15, the tipping element system, or tipping element is the system which may have tipping points. So, the big systems. Nine out of these nine out of these 15 systems are starting to show worrying signs of you know, moving towards tipping points, not that they have crossed, but they show signs of either slowing down like the overturning of <inaudible> Atlantic or higher variability, like for example, the Amazon rainforest and degrees and frequency and droughts, floods and fires. So, it's a signal that something's happening, but these are 15 systems we know of today and which ones are they? Well, they are, you know, the boreal forests, the temperate forests, the tropical forests, the ice sheets, the ocean circulation system, the monsoons, the El Nino systems, I mean, it's a battery of systems, and they all churn and work to regulate the state of the planet. So it isn't one button that suddenly releases the whole system, no.

ML: Right, but it does get interpreted I don't want to say universally, but really almost universally by people who are on the kind of climate activism side of things or climate concern side of things. And as the, you know, the example is the hothouse Earth paper, which is cited endlessly in the, you know, in maybe not in the scientific literature, but in the nonscientific literature, it is essentially waved around as proof that we are tipping and that we're spiralling off and you know, I read it carefully, and it uses the word “could” 47 times “might” eight times and “may” 17 times and yet it gets, you know, it gets sort of, you know, trotted out as the definitive, you know, this is happening argument, and I suppose, to turn that into a question, how do we as scientifically grounded people help to carry out this debate? Because if you just say, sorry, that's a hypothetical, then you're not doing your job. But if you say that is that you're absolutely right, this is happening. But then you're also not doing your job.

JR: No, that's true. And well, just to just to kind of remind ourselves that what the hothouse Earth paper showed is that if we burn fossil fuels, so we reach two degrees Celsius, because humans cause two degrees, what how will we how will the planet respond? That was the question. And we find with a very conservative assessment, that the planet will probably, or very likely, by itself increase temperatures to a further 0.4 to 0.5 degrees Celsius. So, two degrees will mean two and a half. And if you reach two and a half, we are at risk of triggering the next set of tipping point, which could lead to a cascade. And that cascade could lead to a drift of warmer and warmer temperatures. And we put that out as a hypothesis that needs to be researched urgently, because we're heading towards more than two already. And this is what everyone tends to forget that, you know, it's one thing you know, if you go back again, geologically, what took us out of ice ages in the past was that the sun warmed up the planet with a slight fraction, like one to two degrees. And but that doesn't take you out of an ice age one, two degrees, you’re still an ice age. But then the planet itself shifted feedbacks, crossed tipping point and started to self-warm, the remaining two and a half degrees required to go from minus four deep ice-age it to zero preindustrial 40 degrees Celsius planet. So, we know this happens. We know this has happened many, many, many times. And there is history that you have a little kick, and then off it goes. Now we are the kick. Now we are playing the Sun. So, the Sun does two degrees. Now we are doing two degrees, why would the planet respond as it has always done before? That's the question. That's a scientific question. But I think it's a question that has high relevance.

ML: And I 100% agree with the relevance of the question. It's the understanding of the uncertainties, and also the time constants. Because those, how long did it take to come out of those previous, you've got the kick, which in this case is of a speed which has never been seen before? Right? Because it is 200 years maximum, you could define it from 1950 or from 1850. But it's basically the fastest kick we've ever seen. But those reinforcing forces, there's no reason to believe that they would necessarily happen faster than they have in the past, or is there?

JR: No, no, you're absolutely right. That the impact time, not only may, but certainly is, in terms of in many cases, centuries, not even decades, centuries, built into the sea level rise, ice melt, you know, shifting big biomes does not happen just over decades. I mean, if you look again, back geologically, even a transition that takes 2000 years is a very rapid transition. And you're right, now we are warming the planet, much, much faster than any warming in the past. But we can also foresee that the earth as the feedbacks had, there's no reason to believe that they will be faster suddenly than then in the in the record of the planet. So, you're right. The impacts may come very far, the big let's call them catastrophic impacts wouldn't play out until let's say 2,3,4 or 500 years in the future. My question is, does that matter? And I would argue no, I would strongly argue no. Why? Because I think that what matters for us and the responsibility we have, we who are on the watch today, we the adult generation on Earth today, what our responsibility is, in my mind, is the commitment time, not the impact time. When do we press the ‘on’ button making it unstoppable to melt the ice sheet? Well, if that number is two, well then we're very close to it. We might be just decades away. But seven meter sea level rise caused by… might be 400 years away. You're right. And it will be quite a quite a painful journey to get there. But the final outcome is far down the road down, but the commitment time, maybe just round the corner. So, to me, it's a question of also us understanding that what we should probably focus on when it comes to economic policies and political decisions is commitment time, not impact time.

ML: Now I could not agree more. That is exactly how I see it, but it goes to the heart of lots of very heated discussions that I have had. Because, you know, I have weighed in to this debate, you know, I have a Twitter hashtag, which is #RCP8.5isbollocks. And that was that was born out of my frustration of people confusing that commitment time, the amount of time it takes to sort of push the ball to the top of the hills, it starts to roll down the other side, and the amount of time that it might spend rolling down the other side and causing the most catastrophic harms. And that debate, you know, we had, Sir David King over a decade ago saying, you know, if we lose Greenland, then the sea level will rise seven metres in London, and of course, followed by lots of newspaper coverage with picture images of London underwater, something that might… that wouldn't happen for hundreds of years. And so that mismatch of time, to me poisons the discussion, because it leads to people sort of hyping the idea, you can call it climate porn, you can call it RCP 8.5, you can call it, you know, some of the disasters being painted by Extinction Rebellion of near term collapse of society have, you know, and I agree with you, I think we should be enormously worried about those things, but not pretend that if they take hundreds of years that they're somehow going to hit us or our children, we have to have the responsibility, you have to have the maturity to say that's not the point, the point, you know, that there will be things that affect us, but they will be this big, compared to this big of what can happen in hundreds of years or in a thousand years?

JR: No. So I think this is one of the most, perhaps most fundamental issues to resolve because as you know, not only is this misconception out in society, but all economics, all economics fail here, they can only focus on impact time, all the discount rates, everything is just focused on when do you lose your capital, in terms of impact. Commitment, time, nobody charges, nobody puts any price on that. And I think that's one of our biggest failures. And that's, of course, why you have the youth rising. I mean, the whole Friday's for Future is about feeling that is unacceptable, that we commit all future generations to a planet that is in a worse state that it will just gradually move in the wrong direction. And I think this is something that we need to rapidly change the whole debate around.

ML: So there I agree with you that economics has failed us, I think, you know, classical economics, which doesn't look, it's sort of it doesn't look at the path dependencies, and it's got symmetrical outcomes up and down, and it doesn't look at what the down might be loss of an ecosystem, and the up might be whatever. So I think there's no question that economic and the solution to say, well, let's take classic economics and just use a really, really low discount rate, which we then can't really justify that feels unsatisfying to me. But what I would say is that the Fridays for Future and let me get let me get, you know, Greta Thunberg has done an incredible job of communications. But when she says follow the science, very often she is referring to an extreme, these extreme scenarios of science, which are out there, they are even supported by lots of scientists who talk about RCP 8.5 and try to kind of, you know, maintain the semblance of its plausibility. But that's not actually the science that you're describing of a commitment period, which is short, followed by an impact period, which could be in, you know, in a very extended timeframe.

JR:No, that's right. I mean, I would defend Greta Thunberg because I think she leans so heavily on IPCC and of course, you're right, one of the scenarios when the IPCC is this is RCP8.5. And I share with you the critique on that. I've been criticizing that for a very long time. And I find it very unsatisfying that it assumes fossil fuel burning at levels that will never happen. But on the other hand, as you know and Greta Thunberg  knows very well is that the big GCM is the big general circulation models used in the IPCC are yet unable to represent Earth system feedbacks, you don't have tipping points in any of the models. So, while they are exaggerating in their scenario building, fossil fuel burning scenarios, the RCP8.5 future they underestimate risks of Earth system feedbacks. So, there is a… you know, I would never use RCP8.5 to compensate for the fact that you are unable to represent permafrost or but it's still something that we need to recognize that there is that uncertainty out there.

ML: Absolutely, absolutely. But scientists are using RCP8.5 to adjust for tipping points. So we've just had the UK Climate Risk Assessment, lead author Richard Betts , and it mentions RCP 8.5 158 times, which is more than three times any other scenario. And I find that, frankly, I can kind of do this without using words like dishonest. But it is misleading because I agree with you that what… because what's happening is that we are getting an exaggerated concern about impacts this century and in the next few decades. And we're not fully pricing in the impacts in later centuries. And this is very real. So, I was on the board of Transport for London, if you believe RCP8.5, we have to start building more Thames barriers and flood protection essentially now. But if you understand that actually our issue now is to use the commitment time wisely. Because the actual the barriers, the floods would be 2200, 2300, 2400. And there'll be absolutely catastrophic at that point. And it's legitimate to do everything, you know, that we can to avoid them. But the actual commitment of public money is different if you believe we're dealing with a commitment time followed by an impact time or if you've kind of accelerate everything for the purpose of communication to get everybody worried that the floods are coming this century or in the next few decades?

JR: Yeah, no, that's an important point you raise here and I really hope that we through the sixth assessment at IPCC, which will be coming out now in the next two to three months, we'll be able to focus in more on what really matters, which is what happens around the1.5 - 2 degrees Celsius range. Not what happens in this kind of doom scenario of reaching four degrees by just burning up until 2080-2090.

ML: So I had Jim Skea on the on the show, and, you know, sort of walked him through all of this. And, you know, he did he did admit that RCP 8.5 would involve, you know, burning, actually promoting the burning of fossil fuels, it's not in line with what we're doing. But if you look at the other working groups, if you look at the impacts, the Impacts, Vulnerabilities and Adaptation working group, they basically just pull RCP 8.5 off the shelf, it produces these tremendous eye catching results, you know, the penguins will be functionally extinct, and the sea level will be this, there's that and the other and so on. And I'll tell you what I'm worried about in that process is the loss of credibility with the non-convinced, you know, the center-right. Those who are more skeptical, when they see this stuff, they're just going to push back, they do, they've just pushed back enormously because it's not plausible. So, the kind of amping it up that we see from Extinction Rebellion, and so on, it's not helpful, it's actually extremely damaging, because it gets a kind of allergic reaction from the business community. You know, at the moment, they're all kind of, you know, scrambling to catch up, but when they understand how implausible some of this stuff is, you're going to get a big pushback and from the political right, quite definitely, they're not really on board with this at all.

JR: No, but that's it. I mean, then that it's a really important point here. And, as you know, the most, that we don't need that that argument to act to act kind of decisively and even at an urgency level, because, you know, just cutting emissions by half every decade and moving towards a net zero world economy by 2050 and land the Paris Agreement that that's the charge we need, we don't need RCP8.5 to justify that, we can justify just by avoiding passing the two degree point just avoid that commitment point, despite the uncertainty so I never use RCP8.5 for anything, I focus in on where do we have these commitment moments in the biosphere, which would then make the make this… you know, my fear is that we are not the ones causing the forcing we humans, but the earth system is causing forcing itself. And that that shift is what we need to avoid.

ML: Yeah, and I think this is a huge challenge for all of those, all of us who have got the science to communicate, because we are still in an in a world where it's almost like, you know, to use the IPCC scenarios, RCP4.5 is regarded as a good outcome. You look at the US National Climate Assessment. They actually use 4.5, to say, well, you know, here's all the damage, you take the damage of 8.5. And then wouldn't it be much better to be at 4.5. And then you and I look at 4.5 and go 4.5 is a catastrophic outcome. That's the three-degree outcome. We need to be far below that to stay away from these limits, and yet that is in still in vast swathes of the academic work it's still being positioned as a good outcome.

JR: As you know, the hothouse Earth paper builds entirely on RCP4.5. We're not including RCP8.5 at all. I mean, the only interest is what happens when that that narrow range, up until two, so that's an RCP 4.5 range. So, you're right. That is worrying. And then we could enter the whole area of climate sensitivity as well, which is equally kind of concerning here. Because as you know that the next IPCC assessment will show that the climate sensitivity range will go up, slightly, but it will go up. And that is also something that occurs because the climate models have become so much better at representing clouds dynamics and the scaling of the climate functioning with regional weather systems. But it's not because we're factoring in the risk of tipping points. So very likely, the climate sensitivity is even higher, I mean, even if it's just insignificantly higher, but you know, when you run a climate model with a three degree Celsius climate sensitivity, meaning the temperature rise and a doubling of CO2, and just add, just increase that to four instead of three, and the carbon budget is gone, you get a completely different future. So, we have many moving parts here.

ML: Johan, we've got four minutes, I promised you a hard stop at the top of the hour here today. And you have said that you've never been more concerned having done that assessment of, you did the 2018 update to the 2008 work, the update on the tipping points, and you said that you've never been more concerned. But you've also said you've never been more optimistic. So, let's finish on a high. Why have you never been more optimistic?

JR: Yeah, no, to start with, let me just really emphasize that that's from my personal perspective is an objective statement. And in my whole professional career, there's never been a reason to be more concerned based on the evidence we have today. But I've actually never in my adult life had more reason for optimism than today. Why? Well, it's for two reasons. Three actually, but one fundamental, is that we're starting to see so much evidence that sustainable solutions are scalable, and they give better outcomes. So, we're starting to see market parity on renewable energy systems with coal fired plants, we're starting to see so much evidence that the health outcomes are you know, magnifying the benefits of renewable energy systems. We're starting to understand that building resilience in societies and avoiding future pandemics has also to do about nature and sustainability. So, sustainability is changing phase, it really is rapidly changing phase towards both being economically more attractive and it is the pathway towards more security, stability, health, resilience. So instead of being what you and I have been experiencing for decades, an environmental agenda and about protecting and about keeping humans away, and about the willingness to pay, it is now more and more an agenda of competitiveness, it is really a race to zero on climate. And it's truly a shifting… I mean, just to put it simple. I spent two decades working with CSR officers and environmental, you know, heads of environment. Today, CEOs are always in the room. You know, it doesn't matter what I do. It is it is really always of interest also for the boards and the leadership of businesses, policy, society in general. So we're not there yet. We're moving too slowly, there are of course, vested interest everywhere, but there's but there's a new dynamics and there's a momentum and to me, it means that we have, you know, we may have crossed already or we are very close to a social tipping point in terms of making this journey towards sustainability, unstoppable. So, you may have heard me say it and I and I say, you know, without hesitating, that in my mind, it's not a question of if we will be decarbonizing the world economy. The question is will we do it fast enough? Or will we be too late? But we are on the way.

ML: Well, that's a fantastic note to end on, I would agree entirely. I've probably been saying for 15 years or more that we will end up with a net zero with a low carbon or as near zero carbon economy by 2100, for sure. The only because these are better solutions, ultimately cheaper solution with co-benefits. The only question is, do we get there in 2080, 2060, 2050? And what the planet looks like, when we do get there?

JR: Exactly, exactly. I mean, so that there is reason to, that's why there's really reason to stand up, hold hands and work in this sustainable direction, because it's really worth it.

ML: Thank you very, very much for your time. And it's been an absolute pleasure hearing from you. I wish you luck in your endeavors. And we will put links in the show notes to your fabulous Breaking Boundaries documentary and probably a few other bits and pieces that we've mentioned during this last 45 minutes. Thank you very much.

JR: Thank you. Great to be with you.

ML: So that was Professor Johan Rockström talking about planetary boundaries and how not to break them.