Scientists say we still have time to address climate change, and we have made headway, but we still have a long way to go. What do we need to do to combat climate change, and how worried should we be about global warming? Maria Armoudian speaks with renowned climate scientist Michael E. Mann.

Michael E. Mann is a climatologist and a geophysicist. He is the Director of the Earth System Science Center at Pennsylvania State University. He is the author of The Madhouse Effect: How Climate Change Denial Is Threatening Our Planet, Destroying Our Politics, and Driving Us Crazy.


This interview has been edited for clarity and length 

Maria Armoudian: You have said that the tools you and other climate scientists have developed might be increasingly unnecessary because we can actually see the real effects of climate change now. There are two big questions that come out of that. First of all, how would you describe the effects that we can actually see right now?

Michael Mann: That was an appearance I made at a hearing of the Democratic National Committee related to the Democratic platform where I [was] asked to talk to the committee about the science of climate change. The point I [made] was almost a rhetorical point [that] unfortunately some of my detractors went out of their way to take out of context to make it sound like I was saying that we no longer need data and models to do science. That is not at all what I was saying. What I was saying was [that] when it comes to actually seeing the impacts of climate change the impacts are no longer subtle, and it’s no longer necessary to try to tease the signal out of the noise of natural climate variability in the way we would have had to in the past, because the signal has become so large that we can actually see it with our very own two eyes. One [example of this is] the flooding in Louisiana. That was a record flooding event, and we know that the fact that there was so much rainfall was tied to the fact that there was a very large amount of moisture in the atmosphere [which] was tied to the very warm ocean temperatures. The Gulf of Mexico sea surface temperatures have been as high as they’ve ever been. The last year has been a record year, where the oceans have been warmer than they’ve ever been before. What that means is that warmer oceans evaporate more moisture into the atmosphere. There is more moisture available to turn into record rainfall events…  Thousand-year rainfall events [are rainfall events that] shouldn’t happen more often than once in a thousand years. Just over the last year [2016] we’ve probably had about a half dozen of those thousand-year rainfall events, not just Louisiana but Texas, Arizona, South Carolina, and West Virginia. So what we’re seeing in these very large increases in the number of extreme weather events [is] the loading of the weather dice; we’re seeing that the random dice of weather has been loaded by climate change towards these more extreme events. Flooding is just part of it. We’ve seen record wildfires and unprecedented drought in California. [So] we are seeing the impacts of climate change play out now in real time.

MA: As I understood this from reading the literature you can’t really identify one or two of these events and say, “Well this is definitely a result of climate change”, but collectively they are related to climate change.

MM: It’s somewhere in between the two statements. That is partly true, but it’s not the whole story. In fact in our book, “The Madhouse Effect”, Tom Toles and I include a cartoon that actually deals with this question of whether or not you can blame extreme weather events on climate change. There is a little footnote in the cartoon, as there always are in Tom’s cartoons, [that] says, “It’s a loophole you could lose a planet through”. What we mean there is it’s sort of a loophole to be able to say you can never blame any one weather event on climate change. It’s tantamount to saying you can never blame any one death from lung cancer on smoking of cigarettes, even though we know many people die from lung cancer because they smoke cigarettes. It could have happened naturally. So if you’re talking about any one individual, there is always the possibility that it could have happened naturally. That gave rise to a concept called fractional attribution, which is now used in climate change as well. It was used in the legal settlements with the tobacco industry, that some percentage of people who die of lung cancer we know was caused by your product and you have a liability that is associated with that. So even though it’s a statistical connection, real people did die from lung cancer caused by smoking cigarettes, and actual weather events have been made worse in many different ways by the effects of climate change. So when somebody says something like, “Well you can’t prove it was caused by climate change”, it’s a technicality. I always like to use sports analogies, and in professional baseball Barry Bonds broke the record for home runs I think one season and then it was found that he had been taking steroids and the record was invalidated. His defence might be, “For any one home run that I hit that season you can’t prove that that home run was caused by the steroid use”. That may be technically true, but it’s still a loophole.

MA: One of the things that seemed interesting to me is that the changes seem to have happened much faster than we were originally thinking they would happen. Is that true?

MM: In many respects it is true and it really gets at a very important point in that the critics, those who favour an agenda of inaction, will say, “Well there is uncertainty in the science. And as long as there is uncertainty we don’t know for sure that the burning of fossil fuels is a problem. So we shouldn’t take action”. That is not true, but even the very premise behind that sort of reasoning is wrong because uncertainty cuts both ways. Maybe you can get lucky and the uncertainties might cut in the direction of some of the impacts not being as bad as we predicted, but the history of the science seems to suggest the other possibility. In many respects the changes have taken place faster than we predicted. [So] the uncertainty appears to be cutting against us when it comes to the impacts of climate change. And that is true with the loss of Arctic Sea ice…  The Arctic is sort of our refrigerator and as we lose that sea ice that impacts the entire planet in an adverse way… We are losing ice from the continental ice sheets decades ahead of schedule. That means that we are seeing an increase in sea level rise from the melting of that ice. So the sea level rise problem is worse than we expected based on the predictions that were made a decade ago. There are many other examples where the changes and the impacts are playing out faster and worse than what we had predicted.

MA: I imagine that the ecosystems themselves, both in the oceans and of land, are the most severely affected, which then has the ongoing influence on our food and water and that sort of thing. Can you just give us a sketch of what we’ve seen so far?

MM: That is absolutely right. One of the problems is that when you start looking at impacts on ecosystems, on species, on food webs, there is a term we use in science: nonlinear. It means that there are very complex interactions between living things, each other, and their environment, and there is the potential that a small change in the external conditions can lead to a very large change in the behaviour of that system. [In terms of] tipping points, you can have the collapse of ecosystems where a small change in climate upsets the balance such that you really get a far more abrupt and profound impact on the environment [and] on species. Our coral reefs are a very good example. They are under threat right now from multiple insults caused by human activity, climate change being one of them, warming of oceans, and coral bleaching. The increasing [carbon dioxide] in the atmosphere is also making the oceans more acidic and that is literally starting to dissolve the coral reefs. Then you add the pollutants that make it out into our oceans. So they’re being hit by all these simultaneous insults… We know this in our own lives. When one bad thing happens to you, you can deal with it. But when a couple of bad things happen to you it’s a little hard to deal with. When three or four different things are going badly in your life all of a sudden you feel like your entire world is collapsing. That is because we react poorly and all living things react poorly to multiple simultaneous insults. And that is what we’re doing to our ecosystems right now. It’s a cause for worry. We are subjecting them to changes that they have not experienced in the entire history of their existence. We’re doing that in multiple ways; were hitting them with multiple insults.

MA: One of the things that you addressed in the book is your detractors. They had been very vocal historically with the denial and the argument that there wasn’t enough certainty in the science to move policy forward. It seems like they have been quieter lately. Would you say that is true? Or is that just perception because of the media I follow?

MM: It is an interesting insight, and I think that is true to some extent. I think that climate change denialism is becoming somewhat marginalised, at least in our mainstream public discourse. Now there are some important provisos there. For example, Donald Trump is a climate change denier and so climate change denial is still expressed at the very highest levels of our politics. But I do think that climate change denial is less welcome in polite conversation now [partly] due to something that we started out talking about at the beginning of this interview, where people can see that something is happening and the impacts of climate change are no longer subtle. When people can start to see something happening with their own two eyes it makes it very difficult for [them] to tell themselves that it’s not happening. And I think that is really one of the critical developments here, that the profound nature of the impacts of climate change [are] such that it just makes it not credible anymore to deny that something is happening.

MA: In the book you said that we can still avoid the catastrophes [and] maybe even reverse some of it. Do you think that is true?

MM: Yes. The reality is that there is no one threshold. I can’t give you a precise amount of warming of the globe and promise you that if we keep warming below that bad things won’t happen. Let’s face it, there are some bad things that we already see happening just from the climate change that has already taken place. So it’s a matter of how far we’re willing to go down this dangerous road. The experts who have looked at the impacts of climate change have determined that once you go beyond about two-degrees Celsius warming of the planet relative to the pre-industrial time, and we are already about halfway there, we’ve already warmed the planet a degree Celsius, we may have another half a degree Celsius in the pipeline, and so we only have a small amount of wiggle room if we’re going to avoid crossing that dangerous two-degrees Celsius limit. We can still do it if you just look at the numbers; if you crunch the math it is possible for us to bring our emissions down at a rate of several percent a year in the decades ahead such that we avoid crossing that two-degrees Celsius warming range where we really do start to see the worst impacts of climate change.

So if we act now we can avert a catastrophe. We are seeing some progress already due to the amazing developments in renewable energy technology, dramatic increases in the market share of renewable energy, and even here in the US where we have seen a dramatic increase in wind and solar power [and] in electric vehicles. [So] we’re starting to turn the corner. In 2015 the numbers came in and told us that carbon emissions for the first time on record globally actually went down. That’s a direct response to the efforts among many of the nations of the world to try to stem the tide and do something about the problem and transition towards renewable energy. So we’re starting to turn the corner. The problem is we need to turn the corner even faster if we are going to avoid crossing that dangerous threshold of warming. We got an important start in the process in Paris where nearly two hundred nations around the world including the world’s top emitters of carbon agreed to make substantial reductions; enough to cut the warming roughly in half from where we would be going under business as usual, basically getting us halfway to what we need to do to keep the warming below two degrees Celsius. So we’re starting to go down the right path, but we’re going to have to do a lot more if we’re going to avert catastrophic impacts on our planet.

MA: Is there any way for you to be able to explain in specific terms how much we would need to do? Change our energy by X percent, or change our driving habits by Y percent, or change our eating habits?

MM: There are a lot of things that we can do on a voluntary basis that cuts our carbon emissions, decreases our personal carbon footprint etcetera. We ought to be doing them anyway because what we call no regrets actions, like bicycling… rather than driving to work saves us money [and] it makes us healthier. More efficient appliances save us money as well. There are all these things that we can do that cut our carbon emissions and make us healthier, happier, and save us money. We call them negative costs because there is a benefit immediately to doing it, but voluntary actions alone don’t get us as far as we need to go if we are going to avoid that dangerous level of warming. So if you talk to economists they’ll tell you that to really solve this problem we need to put a price on carbon. What that means is when you burn carbon, producers of fossil fuel, energy, and power have to pay for the damage that their product is doing to our planet through some sort of mechanism. It can be a carbon tax [or] it could be some sort of cap and trade system. One way or another we need to put a cost on the burning of fossil fuels so that we level the energy marketplace so that renewable energy which isn’t degrading our planet in the same way can compete fairly against fossil fuel energy which has this cost that isn’t currently represented in the marketplace. There isn’t a price signal right now for the damage that fossil fuel energy is doing to the planet, and until you put a price on the burning of carbon you really don’t have the incentive system necessary to steer us in the direction we need to go. It’s almost like it’s magic: once you cost the damage through a mechanism like a carbon tax then people start changing their behaviour in the direction that we need to change our behaviour because it’s built into the market.

MA: I guess I was trying to get a sense of how much we would need to shift our energy use in order to avert going down a disastrous path?

MM: We have to bring our carbon emissions down by about five percent a year over the next several decades if we’re going to avoid raising [carbon dioxide] levels to where we get that two-degrees Celsius or more warming of the planet. So we obviously need policies that achieve those sorts of reductions. Some of those policy changes are almost invisible to us. If you have a carbon tax then all of a sudden energy producers will increase the percentage of their portfolio that is from renewable sources; from wind, from solar, [and] from geothermal. So the energy that you’re getting comes increasingly from renewable sources. So we might end up paying a little bit more for energy as we go through that transition, but it really is almost imperceptible to the impact that it actually has on our lives. Some people think that we have to fundamentally change our lifestyles to deal with this problem. That isn’t necessarily true. We have existing technology right now that if we scale it up at the rate that we could potentially scale it up, and there are peer-reviewed scientific studies that show this, we could meet nearly a hundred percent of our projected energy needs from renewable energy within a… couple of decades. We can do that, we have the technology to do it. We just need the policy incentives to move us in that direction and.. the way that we lead our daily lives, it doesn’t necessarily need to lead to any dramatic change in our lifestyles. That having been said, sure, there are things that we can do to change our lifestyle that if [made] voluntarily they definitely will help out the problem, but no we do not have to dramatically change our lifestyles to solve this problem. We just need to favour policies that will incentivise the market to move in the direction that it needs to go for us to basically wean ourselves off fossil fuels.

MA: I think you said five percent change is what we would actually need in terms of remissions.

MM: A five percent reduction a year in carbon emissions, and right now renewable energy is almost growing at a rate that will achieve that as long as we incentivise those renewable energy sources.

MA: Solar and the wind are growing at a rate that can almost get us there. So you’re thinking perhaps we can meet that five percent by just a little bit of tweaking?

MM: Yes. Let me give you an example. We sometimes talk about market parity or grid parity when renewable energy becomes as or less expensive than fossil fuel energy. Right now we’re on a trajectory where that will be true probably in a matter of five to ten years. If we did nothing other than just let renewable energy providers do what they’re doing we soon enough would be at the point where it would be cheaper to go with renewable energy anyway. The problem is that we don’t have five to ten years to wait if we’re going to decrease our carbon emissions so that we avoid warming the planet more than two degrees Celsius. That means that you do need extra market incentives that help steer us in the direction that we’re starting to go anyway. So it’s sort of like accelerating the natural process that is already underway, where we are moving away from fossil fuel energy towards renewable energy and in a matter of years. Renewable energy will out-compete fossil fuel energy even without a price on carbon, but we do need a price on carbon to get us there even sooner.

MA: When these policy discussions occur do you still have a sense that the fossil fuel industry is fighting on the other side to prevent the renewable energies from coming online in such a powerful way? Or do you have a sense that they’re going to maybe even buy into the renewable energies in order to stay viable companies?

MM: I think the enlightened companies are going to invest larger and larger amounts of their portfolio in renewable sources. That is the direction that the global economy is going. China recognises that. They are outspending us. They’re investing far more in renewable energy. In fact they have invested so much in solar cell technology that their products have flooded the global market and led to a sharp decrease in the cost of solar panels. The research and development that they’ve done has benefited the entire world with cheaper solar panels. So that is the direction that the global economy is headed, and those countries that get on board are going to be out ahead on this and those countries that continue to rely on fossil fuels for energy are going to fall behind the rest of the world in terms of their global competitiveness.

MA: You mention this concept called the Hockey Stick. What is this?

MM: Back in the late nineties my co-authors and I engaged in a scientific analysis where we attempted to extend the record of global temperatures back in time because we only have about a century and a half of widespread thermometer measurements around the globe. That allows us to construct a curve that shows how temperatures have changed over the last hundred and fifty years and that shows the globe has warmed and continues to warm. But what the instrumental data alone can’t tell us is how unusual that sort of warming might be in a longer-term context. So back in the late nineties, to try to create that longer-term context, we did an analysis where we made use of what we call proxy data to reconstruct how the climate had changed in the more distant past. That led to a curve that depicted our estimate of how temperatures had changed over the last thousand years [which] showed relatively modest changes from a thousand years ago to the beginning of the industrial revolution. In fact a small drop in temperatures [was seen] as we headed into what was known as the “Little Ice Age” of the seventeenth, eighteenth, nineteenth centuries, followed by an unprecedented spike [for] modern global warming that takes us outside of the range of the variation that was evident as far back as we could go. It sort of looks like a hockey stick where the blade is the modern warming spike that indeed is unprecedented as far back as we or others have been able to take these sorts of estimates. Because of the appearance of the graph it got called the hockey stick. It became an icon in the climate change debate; an iconic sort of entity in the climate change debate because it told a simple story.

You didn’t need to understand the complex workings of Earth’s climate to understand what this curve was telling us [was] that there is this unprecedented warming of the planet that has taken place over the last century and a half and by inference it probably has to do with human activity… It became an easy to understand symbol that really conveyed in a very understandable way the profound nature of the changes that we are causing in the climate of our planet. It also became a target for the critics, those who don’t want to believe in the scientific evidence [like] fossil fuel interests and the various groups that they fund who have been doing their best to try to discredit the science of climate change because they don’t want to see any regulation of carbon emissions. The hockey stick curve became a focal point of their attacks and their critiques. I found myself as a young scientist that never had any interest in being in the fray on the larger contentious political issue of climate change and what to do about it. I found myself at the centre of that debate, and ultimately I chose to embrace the opportunity that provided me to inform the dialogue about this very important problem, but it isn’t what I signed up for when I first started out in science.

MA: Some of this is discussed in your book where you talk about how all of the detractors used the ideas about science and trying to falsify science, but using it to try to deny what the facts were telling us. The peer review process, as you and I both know, isn’t perfect. But what the denialists’ say, when they are talking about the peer review process, [is] that there was a groupthink thing going on. What do you say about something like that?

MM: I’ll quote one of the great science communicators of our day, Neil deGrasse Tyson, who has put it very bluntly: “The great thing about science is its true whether or not you believe it”. There are many who just don’t want to believe what the science has to say… Carl Sagan, perhaps the greatest science communicator in my lifetime, talked about how science has this very important self-correcting process. If you’re wrong you will be found out; you will be shown to be wrong because there is too much of an incentive for other scientists to prove you wrong. The more extraordinary the claim you make the more other scientists will be going after you because if they can be the one to take down this very famous study then that brings them much prominence as well. So there is a real incentive for other scientists to try to disprove each other. That is the way you get ahead in science is not by just saying what we already know is correct, [but by] showing us something different; proving that something that we thought was right is wrong. So the incentive in science is to be sceptical. And unfortunately you have some climate change deniers who like to compare themselves to Galileo. Well, simply rejecting mainstream science doesn’t make you a Galileo, it makes you a crank. Real scientists are sceptics and we hold each other accountable for providing compelling evidence. If a study is wrong, if it comes to the wrong conclusion, then the process of science will establish that it’s wrong. That is the self-correcting machinery that comes through peer review, as you describe it, where scientists publish the results and other scientists can go after them and eventually that leads to assessments where there is widespread consensus because there are multiple lines of evidence from different directions that all lead to the same conclusion. When you reach that point where there are multiple lines of evidence from many different teams of scientists all pointing in the same direction that is when you have a robust scientific understanding. And with climate change there is about as widespread a consensus based on many different lines of evidence for many thousands of different groups of scientists as strong evidence for human-caused climate change as there is for the theory of gravity.

This interview originally aired on the Scholars’ Circle. To access our archive of episodes and download this interview, click here.

For more of our audio and visual content, check out our YouTube channel, or head to the University of Auckland’s manuscripts and archives collection.

Disclaimer: The ideas expressed in this discussion reflect the views of the guest and not necessarily the views of The Big Q. 

You might also like:

How can we combat climate change at the civil society level? 🔊

What are the politics of climate change, energy, and disasters? ▶