Air Date: Week of January 5, 2024

Michael Mann is a world-renowned climate scientist and a Presidential Distinguished Professor at the University of Pennsylvania. (Photo: Eric Sucar, Courtesy of Michael Mann)

2023 is likely to go down in history as the hottest year ever seen by humans. But we still have a chance to rein in global warming before it runs too hot for our civilization, says UPenn Professor Michael Mann. He joins Host Steve Curwood to discuss his recent book Our Fragile Moment: How Lessons from Earth’s Past Can Help Us Survive the Climate Crisis.

Transcript

O’NEILL: It’s Living on Earth, I’m Aynsley O’Neill

CURWOOD: And I’m Steve Curwood.

Once the figures for December are officially tabulated, 2023 is likely to set the record as the hottest year ever seen by humans, topping the previous record for global average temperature readings set in 2016. And thanks to the current El Niño weather phenomenon, 2024 could be even hotter. But we still have a chance to rein in global warming before it runs too hot for our civilization, says UPenn’s Michael Mann. He makes the case in his recent book called Our Fragile Moment: How Lessons from Earth’s Past Can Help Us Survive the Climate Crisis. Welcome back to Living on Earth, Professor Mann!

MANN: Thanks, Steve, always great to be with you.

CURWOOD: So your new book uses paleoclimate research and by paleoclimate, I mean, looking way back in time fact back to... what was it.. four and a half billion years ago the Earth started as to be the Earth to frame the implications of this current climate crisis. Why is that kind of research useful when facing human caused climate change?

MANN: Yeah, thanks. Well, you know, I do cover four and a half billion years in a couple hundred pages, which is a challenge. But I do try to draw upon some key events along the way that really do inform our understanding of climate change past natural changes in climate that tell us something about the climate system, and really allows us, for example, to evaluate the models that we use to predict future changes in climate from human activity. It allows us to sort of assess how reliable those models are. It provides some constraints on those models. It allows us to look at past rapid events that might be analogues for what's happening today. And it also allows us to address some of the past events that are sometimes pointed to by what I call the climate doomers — those who insist it's too late to act on the climate crisis. And there are times when they will point to the paleoclimate record and past extinction events as evidence of that. And so I felt it was important to really review the evidence objectively and talk about that. Are we doomed? And what we see when we review the collective evidence is we're not doomed. Our fate is still in our hands. That may not be true, if we continue headlong on this course that we're on of increased extraction of fossil fuels and warming of the planet. But there is still time. And so in my review of paleoclimate of Earth history of billions of years of Earth history is a message of both urgency and agency, as I like to say.

CURWOOD: There's an interesting section in your book where you allude to some research, looking back to the beginning of agriculture, and how, you know, given the wobble as the Earth spins on its axis, so we should have been descending into an ice age six or 7000 years ago, things stayed warm, stayed as warm because of, say, the methane from rice production, and maybe the cutting of trees as well. How fair is it to say that a little goes a long way in terms of affecting this sort of Goldilocks climate that civilization has been able to thrive in?

MANN: Yeah, Bill Ruddiman was a former colleague of mine back when I was at the University of Virginia and formulated back then what's now known as the early Anthropocene hypothesis. We sort of created our own geological period. Now, human beings are such a large impact on the planet, that it rivals, you know, all of the other factors that drive changes in the Earth system. And so we can argue there's a whole new geological epoch that has to be defined for the period during which humans have had such an outsized impact on the environment. And we tend to equate that with the Industrial Revolution, which is when CO2 levels really ramped up. But what Bill pointed out was that you can actually go back 1000s of years, and his argument, and it's not without controversy, and there are scientists who disagree with the hypothesis. But I think he's made an interesting and solid case here, that these long term natural drivers that drive the coming and going of ice ages over many 1000s of years, were actually slowly leading us into the next Ice Age ever so slowly, the planet should have been cooling. And yet it didn't cool.

Global temperatures remained remarkably flat. He argues that that's because already through rice cultivation, deforestation, and other activities, human beings were impacting the climate, very moderately, just enough to offset a very small natural cooling trend that would have occurred. And so it really is an example a little bit of a good thing, a little bit of impact on the climate, actually kept global temperatures, as stable as they were. The problem is we got more and more efficient at impacting the climate. We started burning fossil fuels, oil, natural gas, and coal. And pretty soon we're having not a modest small impact on the Earth system, but a massive impact. And that's where we are today.

CURWOOD: Now, your book both highlights the degree of the crisis, but also dispels some apocalyptic myths about where we're headed right now. For example, you explain why runaway climate change is not inevitable, because of say a methane bomb. And by the way, what is a so called methane bomb and why is it unlikely to occur and lead to runaway climate change? I mean, I believe you mentioned methane bombs as part of the paleoclimate history.

MANN: You know, a lot of the sort of doomism that you hear today, this idea that it's too late to even act on climate because we have, you know, unleashed runaway warming that will lead to our extinction no matter what we do. And there is a pretty large movement, so called deep adaptation, you know, a movement that has widespread appeal to a fairly large number of people out there been taken in by this sort of narrative that, you know, we now just have to find a way to adapt to this harsh new existence, because there's nothing that we can do to stop it. And the argument is premised on the notion that, for example, we have unleashed methane from the permafrost of the Arctic, the warming of the Arctic has caused the release of methane, a very potent greenhouse gas, it can potentially push us across certain thresholds. The idea is that we've released massive amounts of methane that are going to push us beyond catastrophic thresholds. And it's unstoppable because the warming is in place. It's a runaway we call feedback mechanism, and we can't stop it. And that notion is often premised on the idea that we know that's happening today because it's what happened in the past with past extinction events. The sort of doomers out there will point to, for example, a period known as the Paleocene Eocene Thermal Maximum just rolls off the tongue, the PTM, as we call it. Fifty-six-million years ago, there was a fairly abrupt natural warming event. And it did lead to all sorts of consequences, extinction of many species.

The doomers will argue that it was caused by the same sort of release of methane, the unstoppable release of methane that's happening today. And so I spent quite a bit of time unpacking what the evidence actually says about the PTM, looking at it in some detail. And the best available science now suggests that methane at most was a very small player. The main factor was the release of carbon dioxide, in this case, a natural release of carbon dioxide over 1000s of years from an unusually active period of volcanism, in fact, volcanoes located in the vicinity of Iceland that just pumped huge amounts of carbon dioxide into the atmosphere over 1000s of years. And so the lesson here was the massive warming was caused by the release of the very same greenhouse gas, carbon dioxide, that we are releasing today through unnatural activities, the burning of fossil fuels, and we can do something about it. We can stop the generation of this carbon dioxide and the continued warming of the planet. So the real lesson here is about the agency that we still have in preventing catastrophic warming.

CURWOOD: So the Biden administration issued the Fifth National Climate Assessment in the fall, how does that assessment stack up? I mean, where is it strong? And from your perspective, not so strong? What more should it do? And what did it do well?

MANN: Yeah, I think the report is a good summary of the mainstream scientific understanding. You know, it's sort of driven by the climate models that we have today, much of the, you know, the predictions are really based on climate models. Some of our own work suggests that there are certain types of extreme weather events, for example, that aren't really being very well captured by the climate models. And it has to do with subtle sort of the subtle physics of the behavior of the Jetstream when you warm up the planet, that are difficult to capture in the still somewhat coarse resolution global models that we use. So I've argued that you know, these models are probably underestimating the impact that climate change is already having on these very destabilizing extreme weather events. It's really where the rubber hits the road is with these extreme events, the wildfires and floods and heat waves and droughts, superstorms. The models may be underestimating the dynamic nature of the ice sheets. The ice sheets might not be quite as stable as the climate models envision them as being, which means we could see more rapid disintegration and faster sea level rise. Uncertainty, as I like to say, is not our friend. And so while the report does a good job summarizing the mainstream scientific understanding, that understanding is substantially driven by the models we have and those models aren't perfect. Uncertainly isn't our friend. The models may be underestimating some of the threats that we face.

CURWOOD: Sounds to me like you're not exactly thrilled with some of the predictions that the National Climate Assessment makes regarding extreme weather events, and sea level rise and that sort of thing.

MANN: I think these reports tend to be conservative because they stick pretty close to like what can be justified based on the state of the art climate models. I certainly wouldn't fault my colleagues. And I would point to some of the successes at the same time. The models have done a remarkably good job in predicting the overall warming of the planet. People love to poopoo the models. But in fact, if you look at early predictions of warming, those predictions have been right on target. So if you feed them the increase in carbon dioxide, that has actually resulted from the decisions we've made, or the decisions we haven't made to curtail fossil fuel burning, the models warm up almost exactly the right amount. Where they tend to go wrong is in some of the more subtle consequences of that warming, the complicated dynamics of the ice sheets. They're difficult to model in this context accurately. There are processes that we know occur in nature that we're still having trouble representing accurately in the models. Same thing with extreme weather events, subtle features, the Jetstream that are difficult to capture in some of these models. And so the lesson is, it's sort of a mixed picture. They've predicted the overall warming of the planet quite well. And that's important, because so many consequences are related to that. But some of the impacts have probably been under predicted. And the assessments have to be based in part on guidance from the models that we have. And to the extent that those models are overly conservative with respect to some of the consequences, those assessment reports, the IPCC assessments and the National Assessment Report of the United States are going to under state some of those potential consequences.

CURWOOD: So Professor Mann, we're putting you on the air at the beginning of 2024, to give us some hope, going forward for this next year, in the aftermath of a Conference of the Parties at the UN summit, that some people found less than satisfactory. So it's interesting, though, because COP28, some people say, well, there was progress made, and other people say, but that progress is totally insufficient to what needs to be done. And in a way your book says, "Well, if we are kind of in the middle, and doing something, things may not turn out so bad. It may not be a totally existential threat to our civilization." How fair is that?

MANN: Yeah, you know, right now, we haven't yet seen the progress necessary to limit warming to 1.5 Celsius. It's a little under three degrees Fahrenheit, if you do the translation. That amount of warming of the planet will be deeply problematic, not civilization ending, but if we exceed that amount of warming, there's going to be that much more damage that much more mortality and harm than we've already seen. And we will start to see the erosion of our adaptive capacity, especially those in the Global South, who are facing some of the worst consequences of climate change already. So we are sort of in that in between area where we're seeing progress, perhaps enough progress to prevent what we might think of as sort of civilization ending climate change, but not enough progress to avert great amounts of damage and harm. That's where we are. And that window of opportunity to limit warming, again, below 1.5 Celsius, we're at 1.2 Celsius, we want to keep it below 1.5 Celsius, to avert some of the worst consequences, that's not a lot of wiggle room. And that window of opportunity to decarbonize our civilization fast enough to avert that amount of warming is closing with each COP. With each Conference of the Parties, where we don't see a substantial ratcheting up of the commitments from the various countries of the world. That window gets shorter and shorter, gets smaller and smaller. And that's where we are right now.

CURWOOD: So, Michael Mann before you go, your book, Our Fragile Moment, ends with a message that while the situation is in a perilous state, there is still time to change course. So as 2024 begins, what do you think the next steps are for the United States? And what do you hope from the rest of the world as well?

MANN: I don't think there's any path to meaningful global climate action where the United States fails to lead. We are the world's largest cumulative carbon emitter. China may be emitting more carbon right now, but we've put more carbon dioxide into the atmosphere than any other country. And, in the end, that's what the climate system cares about. It cares about the accumulation of carbon dioxide in the atmosphere. That means we have, you know, the greatest responsibility to take leadership. And when the United States does lead, we've seen that other countries like China tend to come to the table. So U.S. leadership is critical. There is no possibility of U.S. leadership on climate if we fail to preserve democratic governance in this country. Our democracy is on the line in this next election. And people need to think about that, because if we fail to preserve our democratic institutions, it's very difficult to see how we act when it comes to the crises we face like the climate crisis.

CURWOOD: Michael Mann's book is called Our Fragile Moment: How Lessons from Earth's Past Can Help Us Survive the Climate Crisis. Thank you so much, Professor.

MANN: Thank you, Steve. Always a pleasure.

 

Links

About Prof. Michael Mann

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Learn more about COP28

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