Climate Scientist Michael Mann on Preserving “Our Fragile Moment”

Climate Scientist Michael Mann on Preserving “Our Fragile Moment”

Sep 27, 2023
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On this episode of Mathematica’s On the Evidence podcast, climate scientist and author Michael Mann discusses his new book, Our Fragile Moment: How Lessons from Earth's Past Can Help Us Survive the Climate Crisis.

For anyone looking to understand Earth’s climate history and the unfolding climate crisis, Michael Mann has got you covered.

Mann is the Presidential Distinguished Professor in the Department of Earth and Environmental Science at the University of Pennsylvania and director of the Penn Center for Science, Sustainability, and the Media. He has authored numerous books, including The New Climate War and The Hockey Stick and the Climate Wars. He was selected by Scientific American as one of the fifty leading visionaries in science and technology in 2002 and was elected to the U.S. National Academy of Sciences in 2020.

“Climate doomism” – the idea that it’s too late to act on the climate crisis – is a common refrain that promotes inaction. But in his new book, Our Fragile Moment: How Lessons from Earth's Past Can Help Us Survive the Climate Crisis, Mann argues that we can avoid catastrophe if we take meaningful action to address the crisis.

On this episode of Mathematica’s On the Evidence podcast, I speak with Mann about his new book and preserving “our fragile moment.” Topics addressed include:

  • Lessons that can–and cannot–be drawn from Earth’s climate history
  • Why seemingly insignificant temperature changes aren’t so insignificant
  • The concepts of urgency and agency, and obstacles to climate action
  • “Shifting baseline syndrome” – the gradual change in expected norms for environmental conditions
  • Weighing the paleoclimate record with other sources of information about the climate system
  • Effective communication and messaging strategies around climate science and climate change

Watch the episode below or listen on Soundcloud here.

View transcript

[Michael Mann]

What does the paleoclimate record actually tell us? It doesn't tell us that we are doomed. It does tell us that we're in for a world of hurt if we don't get our act together. And so this sort of pairing of urgency and agency. Urgency without agency leads us down the wrong path. We have to recognize that, yeah, it's bad, but we can do something about it. We can still do something about it.

[Rick Stoddard]

I’m Rick Stoddard from Mathematica, sitting in for J.B. Wogan, and welcome back to On the Evidence.

On this episode, my colleague Mike Burns talks with climatologist and author Michael Mann about his new book, Our Fragile Moment: How Lessons from Earth's Past Can Help Us Survive the Climate Crisis.

Mike spoke with our guest about lessons that can–and cannot–be drawn from the data and evidence we have about Earth’s climate history, the need to counteract collective acclimation to extreme climate events—a concept known as shifting baseline syndrome, and how to effectively communicate issues of climate science and climate change to motivate people to learn more, and take action.

[Mike Burns]

Dr. Mann, thank you so much for joining us today on On the Evidence. So you're out with a new book, Our Fragile Moment, Our Fragile Moment being this idea that the conditions that allow us to live on Earth are fragile and we need to act before it's too late. In your book, you examine Earth's climate history, these critical climate changing events throughout the Earth's 4.5 billion years. And you show what lessons can and cannot be learned from these events. What are some of the most important lessons?

[Michael Mann]

Yeah. So you know what I really try to convey in the book, you know, there are lessons sort of that speak to the resilience of the Earth’s system. And there's a little reason, you know, there's some reason for hope there, that there is some amount of resilience in Earth's climate system and the climate history of the planet teaches us that. But it also shows that there are points beyond which that resilience very quickly erodes. And so there's this sort of balance between resilience, to an extent, and fragility if we go past sort of the limits of that resilience. And we can find examples of both. The examples I really like to use to convey that duality is, you know, the sort of the faint early sun paradox. Four billion years ago, the sun was only about 70% as bright as it is today, 30% dimmer than today. So the Earth should have been a frozen planet, but it wasn't, it turns out, because there was a stronger greenhouse effect. This paradox was first recognized by the great Carl Sagan and proposed the solution was that the greenhouse effect was stronger at that point to counteract the dimmer sun.

And remarkably, as the sun got steadily brighter over time, the greenhouse effect in general got weaker. And those two things work together to keep the planet within habitable bounds. And so in these very long timescales, there are these restoring mechanisms that have to do with Earth’s carbon cycle. And life itself plays a role in that. Gaia, the Gaia hypothesis sort of speaks to that role that life itself has in keeping the planet within habitable bounds. Yet at the same time, there was an episode a little less than 3 billion years ago. We call it the Great Oxidation Event. There was a sort of an innovation life developed a new mechanism for photosynthesis that produced large amounts of oxygen. And that oxygen, that huge spike in oxygen, reacted with the methane of the early earth atmosphere. And methane is a very powerful greenhouse gas. It was scavenged away by this oxygen, and so the greenhouse effect decreased very quickly. More ice formed, and when ice forms, it reflects more sunlight. So you get even more cooling. It's a vicious cycle, a positive feedback, as we call it, that literally sent Earth into a completely frozen state, snowball earth.

And so these both serve as sort of cautionary tales, I suppose, that there is resilience to an extent, but there is also fragility when you go beyond that. We see that with the Great Oxidation Event. And, you know, arguably we're seeing that today with rates of change. We're putting carbon pollution into the atmosphere at a faster rate than nature has ever done in the past.

And we're encountering rates of change that go beyond anything we've seen before and challenge the resilience both of ourselves, of our civilization and of other living things on the planet. And so there's sort of a message here that, you know, within some range there are these stabilizing factors that work to our benefit. And it turns out that sort of ends up telling us that there is still time to act to prevent the worst impacts of climate change. But if we fail to act, nature's history also tells us that some truly bad things could happen, destabilizing mechanisms that would pose a threat to us, to civilization, other living things. And so that that's what's fragile about this moment. We're in that sort of window of opportunity right now. But if we go beyond it, then everything's on the table.

[Mike Burns]

Along those lines, you know, you go through different climate scenarios and one of them is, you know, if we just maintain current policies even without additional action, you know, we could expect at most a five degrees Fahrenheit warming. What would you say to someone who hears that number and thinks it's relatively insignificant?

[Michael Mann]

Yeah. So, you know, there is once again, there's a balance. And the balance here is that, you know, if, you know, we're making some progress right now in decarbonizing our civilization, we're not doing it fast enough, but we've made enough progress that we're no longer headed towards like eight or nine degrees Fahrenheit warming of the planet. We're headed in the absence of additional policies towards something more like four to five degrees Fahrenheit.

And so people might look at that and say, oh, well, all right, we've nearly cut the warming in half. We're fine. Right? What's the problem? Well, if we go beyond about three degrees Fahrenheit, let me put it this way. Right now, we've warmed the planet a little over two degrees Fahrenheit, about 1.4 degrees Celsius. And look what we're already observing. Look at the disastrous extreme weather events that we've just lived through this summer, at least in the northern hemisphere, our summer, we've seen these, you know, catastrophic heat waves, heat domes, wildfires, floods. We've seen it all. And that's just that, you know, three degrees Fahrenheit. If we go to four or five degrees Fahrenheit, all of this gets much worse. And already these, you know, these events are starting to really tax our resources were spread thin. FEMA is basically run through their budget now in dealing with the wildfires out west and the landfalling hurricane we just dealt with back east. And so, you know, pretty quickly, we will once again exceed our adaptive capacity if we warm the planet well beyond where we are now.

So the good news is there's still time to keep that warming under about three degrees Fahrenheit. The bad news is if we go to four or five, you know, we're already seeing dangerous climate change impacts. At that level, we'll start to see some catastrophic impacts.

[Mike Burns]

So you clearly did a lot of research for this book. How did you identify the best data and evidence to use?

[Michael Mann]

Thanks. I mean, it was sort of a return to my bread and butter. I sort of started out as a as a paleoclimate scientist early on in my career. And so now here we are 25 years later, roughly. And I decided it was a good time to sort of take stock, to go back to my roots and address this sort of this prevalence today of doomism. And we see very widespread, especially among younger folks, this idea that it's too late, it's too late to stop this juggernaut, to stop this, you know, climate change from a runaway warming scenario. And this notion that, you know, it's almost not even worth trying. And so, you know, in many cases, this sort of doomism is premised on this idea that we are headed for extinction no matter what we do. And I've seen, sort of, proponents of that viewpoint point to the paleoclimate record, like the End-Permian extinction, some of the other past natural extinction events, and argue, Hey, this is what we're in store for. And it turns out that they invariably get the science wrong. They're distorting what the past has to tell us. Ironically, in the same sort of way that we're used to seeing, climate change deniers distort the evidence.

Now we have climate change doomers distorting the evidence to sort of support this narrative of doom, and then it's been weaponized by bad actors. Fossil fuel sort of interests who, you know, realize they can't deny climate change is happening anymore. But if they can convince us it's too late to do anything, then maybe they can sort of, you know, lead us towards disengagement rather than being on the front lines demanding action.

And so I felt like this was an important time to take stock. What does the paleoclimate record actually tell us? It doesn't tell us that we are doomed. It does tell us that we're in for a world of hurt if we don't get our act together. And so this is a sort of pairing of urgency and agency. Urgency without agency leads us down the wrong path.

We have to recognize that, yeah, it's bad, but we can do something about it. We can still do something about it.

[Mike Burns]

And on this, this concept of urgency and agency, it's prevalent throughout your book, the idea that we need to act, but we can act. There is some reassurance about Our Fragile Moment. And you write that the obstacles to action aren't technological, but they're political. What can people do?

[Michael Mann]

Yeah, great question. You know, we have to recognize that there are lots of things that we can do. Now, some people will say, all right, well, I'll, you know, reduce my energy usage and I will put solar panels in my house and I'll stop flying. And there are all these things that we can do, sort of behavioral changes, changes in our own lives. And we should certainly do the things that we can within the constraints of our lifestyles that help us decrease our environmental impact and our carbon footprint. Why wouldn't we do those things? But we have to recognize that the most important thing that we can possibly do is to use our voice and to use it collectively and that means voting. That means engaging in collective action, putting pressure on policymakers, helping elect politicians who will support climate forward policies and help get getting rid of those politicians who refuse to who would rather just be rubber stamps for the fossil fuel industry, because we as individuals can't effect the large scale changes in our infrastructure that we need in order to decarbonize our lives.

We need our policymakers putting in place incentives that will collectively lead us away from fossil fuel energy towards clean, renewable energy, conservation and all of the behaviors that we know collectively we need to encourage. And so the most important thing we can do is as individuals is engage in collective action. And that means voting in every election, not just the presidential elections, but the midterm and the off-term elections and vote from president all the way down to dog catcher voting for climate forward policymakers who will do the things that we can't do alone, that we can't do as individuals.

[Mike Burns]

Thank you. And I was talking with a colleague recently about this idea of shifting baseline syndrome. Does that factor in at all to society's efforts to address climate change? And if so, is there anything we can do to overcome that?

[Michael Mann]

Yeah, it's a great question. You know, there's this, and there's some studies now that show that when it comes to extreme weather events, there is this sort of shift shifting baseline in our perceptions. We sort of adjust as, you know. As beings, evolution sort of designed us to adjust to change sort of our standards as conditions change. And so we tend to simply take as a given as we start to see these extreme weather events that well and how many times we heard the term new normal, “oh, we're just dealing with a new normal.” But it's worse than that. It's a different kind of shifting baseline now. I’m not talking about the shifting baseline of our expectations and behavior. I'm talking about the shifting baseline of how extreme these events are. They will continue to get more and more extreme. It's not like we fall into some new normal. It keeps getting worse if we continue to burn fossil fuels and add carbon pollution to the atmosphere. So we have to be aware of that sort of sensitization that you're talking about, that normalization that, oh, well, you know, this is okay. This is just the way life is now.

It's not. I mean, we're seeing truly catastrophic influences, impacts. You know, the better part of a thousand people, it looks like, perished in those wildfires in Maui a couple of weeks ago. And there's a climate story there. That event was worse than it would have been, far more deaths than there would have been if it wasn't so dry, if there wasn't so much fuel for that wildfire to expand and do the damage that it did.

And so we are seeing, you know, human fatalities now from climate change, exacerbated extreme weather events. And we can't allow ourselves to become numb to that. We can't allow ourselves to become inured to that. We have to recognize that this is bad and it'll get a lot worse if we don't act.

[Mike Burns]

You mentioned before the paleoclimate record, which of course you're looking at going back several billion years. You mentioned that and I really like how you describe the climate science as giving us a fuzzy crystal ball. We can look at this record, but it's not a forecast model, despite what The Day after Tomorrow tells us. The record is murky on top of that, and it really should just be viewed as one important source of information. How do you weigh that evidence with other sources of information to make future predictions?

[Michael Mann]

Yeah, you know, it's important to recognize that, you know, the past isn't always prologue, and that's the final chapter of the book. There are rates of change that we're seeing that have no precedent in the past. So we can look to the past for times when carbon dioxide levels were as high or even higher than what we're headed to today.

We can look for those past sorts of analogs, but we're hard pressed to find anything as rapid as what's happening today. And so that means we you know, we have to take some pause from that. There are lessons we can learn about both, you know, resilience and fragility. There were past rapid warming events like the event 50 million plus years ago, the PETM. It's called the Paleocene-Eocene Thermal Maximum. But it was a time when there was a fairly rapid natural input of carbon dioxide into the atmosphere through tremendous volcanic activity. But that happened, you know, about a hundred times slower than, or a thousand times slower than the CO2 we're putting into the atmosphere today. But it was rapid by geological standards, and there was a fairly large amount of warming in response to that.

And we can use events like that to give us some idea of how sensitive the climate is to increasing carbon dioxide levels. We can look at how much cooling there was at the end of the last Ice Age. And that also tells us about the sensitivity of the climate. How sensitive is the climate to these external factors? That allows us to sort of refine our models. It allows us to determine which models are credible and which models aren't credible. So that's important. But to project forward, since there's no analog, no analog for the rates of change we're talking about, we have to turn to other lines of evidence, other ways of knowing, and that includes climate models. These now very elaborate, remarkably comprehensive models of our atmosphere and ocean and the ice sheets and the global carbon cycle, the role of life.

These are potentially extremely complex models that really seek to include all of the most important interactions that determine our climate system. And they've passed some really important tests with, you know, with flying colors. And so there's reason to take their predictions seriously. And we can use these models and we can project forward under different scenarios. What if we really ramp down our carbon emissions? How much warming will we get? What if we just continue with business as usual? Or what if we burn every scrap of fossil fuels we can find?

We can look at all those scenarios, and in some of those scenarios it looks really ugly. So those models help tell us what do we need to do to prevent those worst impacts.

But as you said, it's a fuzzy crystal ball. I think that characterization was first made by my good friend and mentor who is no longer with us, the great Steve Schneider, who used that framing, fuzzy crystal ball. Not all climate models predict the same amount of warming for a given scenario because different models treat clouds differently or they treat certain aspects of the ocean or atmosphere differently, credibly, but differently because there's uncertainty.

And that uncertainty translates to a spread. So we don't get a single prediction. We get a range of predictions. If we, you know, double CO2 concentrations in the atmosphere, you know, maybe we'll be really lucky and only get, you know, two and a half degrees Celsius of warming. But maybe we'll be really unlucky and we'll get four or five degrees. There's that much uncertainty. Uncertainty isn't a reason for inaction. It's a reason for even more concerted action because of the possibility, if those higher end, you know, predictions are right, things could be far more worse than we currently predict. And so, you know, uncertainty, as I like to say, isn't our friend. The paleoclimate record tells us that. And when we combine it with climate models and observations and everything else, we really start to get a more robust picture of the climate system and where that limit to fragility lies.

[Mike Burns]

Dr. Mann, One final question. I know the topic of communicating on climate science is important to you, and you mentioned scientists like Sagan, who are not just brilliant scientists, but who are excellent communicators as well. What do you think are effective strategies for reaching folks who maybe aren't, you know, following this very closely about making the link between increasing frequency of disasters and the tepid pace of global decarbonization, let alone still rising greenhouse gas emissions?

[Michael Mann]

Yeah, thanks. It's a great question. You know, scientists too often speak in very technical terms and we lose our audience very quickly. Carl Sagan, you know, the great Carl Sagan and other great science communicators, and Steve Schneider, who I mentioned, a climate scientist who is a great climate science communicator. My colleague Katharine Hayhoe, who's also a climate scientist, a very effective communicator.

You know, the rule I'll tell you, Steve Schneider had a great sort of set of three principles for communicating science to the public if you're a scientist. Know thyself, you know, basically know your strengths and weaknesses as a communicator. Try to play to your strengths. Be comfortable in your own skin. Use your own voice. Be authentic, because inauthenticity is very obvious to the listener. Know thyself.

Know thy audience. Speak to the audience in terms that they'll be able to understand and appreciate. And that'll be different for different audiences.

And finally. So there's know they self, know thy audience, and know thy stuff. Know your stuff. Know the science and not just the science that you're doing in your research, because that's not going to cover the full gamut. If you really want to communicate about the climate crisis, you've got to understand not just the physical science, but the analysis of impacts and all the other aspects of the problem, the ethics, the politics, the economics, because this is about, you know, our entire world. Climate change impacts every sector of society, every facet of our lives. If you want to really speak to the climate crisis in full, you really need to be able to speak to all of those things.

And you have to be clear. When am I speaking as an expert? It is research in this area. When am I just speaking as a citizen who understands the importance of governance? It's important to be honest with your audience, when you're speaking out of expertise and when you're speaking based on, you know, what you know, as somebody who is steeped in the literature and is trying to speak to all these other dimensions of the problem.

But yeah, know thy self, know thy audience, and know thy stuff.

[Mike Burns]

Well, Dr. Mann, you certainly seem to know your stuff. I want to congratulate you on your new book, Our Fragile Moment. Where can folks who are interested get the book and where can they find you?

[Michael Mann]

Oh, thanks so much. So you can find me on social media just about every, Twitter or X. I'm Michael E. Mann, but I'm also on Mastodon and Threads and Facebook and Instagram and most of the others. My website’s And you can find our book at Amazon, Barnes and Noble, our publisher, Public Affairs Publishing, their web page. And of course, your independent book dealers. It's really important to give them business. In fact, I'll be doing some events over the next few weeks at Midtown Scholar in Harrisburg, Pennsylvania, and at Powell’s books in Portland, Oregon. And I'm really looking forward to those events. So Google the book, you should be able to find it, and I hope you'll check it out because I think it really does inform where we are and what we need to do at this perilous moment, at this fragile moment that we're looking at right now.

[Mike Burns]

Thank you, Dr. Mann. It was a pleasure.

[Michael Mann]

Thank you. Pleasure was mine.

[Rick Stoddard]

Thanks again to our guest, Michael Mann, and thank you for listening to another episode of On the Evidence, the Mathematica podcast. If you liked this episode, please consider subscribing to catch future episodes. We’re on YouTube, Apple podcasts, Spotify, and other podcasting platforms. You can also learn more about the show by visiting our website at

Show notes

Learn more about Mann’s new book, Our Fragile Moment: How Lessons from Earth's Past Can Help Us Survive the Climate Crisis

Read Mann’s full bio

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Mike Burns

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