David R. Henderson  

Friday Night Audio: Christy "Versus" Emmanuel

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A friend recently recommended Russ Roberts's Econtalk episode in which he interviews climatologists John Christy and Kerry Emmanuel in front of a large audience at the University of Alabama in Huntsville. I listened to it and followed along with the transcript and it is excellent.

In the area of global warming, it's hard to find a civil discussion between two experts who disagree. This is one. Partly, I think, it's because Russ does a good job of being even-handed and drawing out the facts and conjectures. But probably more important is that both Christy and Emmanuel are reasonable people.

Some excerpts follow.

From Christy's opening statement:

3:00: Today and for the foreseeable future, the reliable energy that enhances human life and which is economically viable comes from burning carbon. That will continue no matter what our country decides to do. Does extra CO_2 cause climate problems? The observations tell us not much is happening to the climate that hasn't happened before. Now, a fundamental aspect about the scientific method is that when we understand a system, we can predict its behavior. That has not happened for our climate system. It is true that we have an expensive climate modeling industry that shows scary changes. But they are unable to replicate the actual climate system today. In fact, 100% of the latest climate models overshoot the key target variable of climate change detection. And there is no model that has been rigorously validated for reliability. We are not bad people for burning carbon. Indeed, from my experience from living in Africa, I can say with conviction that we are good people, because of the immeasurable enhancement to human life that carbon now provides.

From Emmanuel's opening statement:
4:35: And not long after that, the Swedish chemist, Svante Arrhenius, found out that the climate is heavily regulated by one of the greenhouse gases, carbon dioxide, whose mass represents four ten-thousands of our atmosphere--a tiny trace. And calculated that without that four ten-thousands part of our atmosphere that is carbon dioxide, the earth would be a snowball. We wouldn't be here. We couldn't survive. This is not in dispute, this finding of the scientific community. It was not made with supercomputers. It was made with pencil and paper, and it can be replicated today. If that tiny amount of greenhouse gas is what is making our planet habitable, then there would be no surprise that if we double or triple it, we are taking a risk with the climate system. And that's how it has to be viewed. It's a risk. So, going forward, we are taking a risk. Not with ourselves--not with me. I'm old enough that it doesn't matter. But with future generations. And a rational people deal with a risk rationally. And my whole program is to try to de-tribalize this debate. You know, it's not about this is going to be a climate catastrophe on the one side, or nothing on the other. And it's also not about trying to do something about it--it will be an economic catastrophe on one side or won't have any effect on the other. That's not the way the world works. The world is more complex. We have a set of poorly quantified risks for action, and a set of, maybe, as poorly quantified risks in taking action. That's the problem we have to deal with.

Here's one of the most interesting parts:
27:20: Roberts: I want to bring up another issue, in terms of what we know and don't know. What is your feeling, Kerry, about the apparent--and you can challenge the claim if you like--the apparent pause in temperature rise over the last 15 years? Again, as a crude, empirical--a mere social scientist, yes, I confess. When I look at the raw numbers of the temperature nominally over the last 15 years, it looks awfully flat to me. Is that correct?
Emmanuel: M hmm. [Yes.]
Roberts: And given that the rise in CO_2 over that period has been the same as before--it's been rather dramatic--how do you explain that? What's your position on it?
Emmanuel: Well, I would be dishonest if I told you I understood that. First of all, yes. The temperature, the global mean temperature, is pretty flat for 15 years. It was also pretty flat from about 1952 to the 1970s or so. So it's not the first time it's flattened out. And what we're--I don't think the community of scientists is very sure about, is whether we're seeing a manifestation of internal variability, natural oscillations that happen to be working against the radiatively forced signal at the moment, or whether there is something about the radiative forcing that we haven't understood. For example, my colleague at MIT (Massachusetts Institute of Technology) Susan Solomon just last week published a paper--I think it was in Science, I don't know if you saw it--suggesting that the fact that we've had a large number of relatively mild volcanic eruptions in the last 10 or 15 years may have put enough aerosol collectively into the atmosphere to affect the temperature. Now I haven't had a chance to digest that. I think the scientific community does have to get on top of this--and in fact all the other periods of reduced and enhanced warming in the past.
Roberts: Does the Pause give you pause? You were confident that there is a small chance of a large rise, based on the rough science and some of the models. Does it cause you to be a little more conservative?
Emmanuel: Well, no. Not really. I think that range [2.5 to 9 degrees Fahrenheit] was generous enough that I would stick with it, until--maybe if we had 30 years of Pause. That would give me pause.

29:55: Roberts: What are your thoughts on the so-called Pause, John?
Christy: I have no idea why it happened, but my thoughts are back to what I have said in the introduction. When we understand a system in a scientific way, we can predict its behavior. I know of no one who predicted a flat temperature trend for the past 15, 16, 17 years. We were all under the belief--me, included--that CO_2 forcing would cause even more warming. And yet it did not happen.

40:50: On the ocean level:
Roberts: And what kind of magnitudes of sea level change do you think we are talking about here?
Emmanuel: Well, this is--the best estimates from the last IPCC (Intergovernmental Panel on Climate Change) reporter on the order of a meter or so--3 feet by the end of the century. But everybody who is in that business says there is much more uncertainty about that than anything else. And one of the problems is that we don't actually understand the physics very well. You'd think we would by now. If I'd written a book called "What We Don't Know about Climate Science," it would have been an encyclopedia.

48:48: Policy Views:
Christy: The risk of something bad happening by making energy expensive is real. People will suffer if energy prices go up; we already know that; there's just no question about that--and as I said, living in Africa, I know what energy poverty does--it kills people. And so anything we can do to allow energy to expand into those areas that do not have it is going to enhance human life and welfare. So, solutions to--if you are really concerned about the carbon dioxide then how can you create energy that is affordable--that's the only kind that really works in the economy--what choices are out there? And the big one that can answer the question is actually nuclear power. We're sitting right here between a couple of big power plants, actually. And it's difficult. It's a bet-the-company move right now for the few that are trying to build nuclear power. And that's probably got to change.
Roberts: Kerry?
Emmanuel: Well, I actually agree with that. I think it's a mistake to do anything that increases world poverty. The history of this is very clear. Economic gains particularly in developing countries are largely, very strongly tied to the consumption of energy. So, we have to be clever about how we attack this risk. And I'm not of the camp that says, we should just go cold turkey on fossil fuels. We can't do that. Nobody in their right mind would suggest we do that. But we should try to approach this risk as intelligent people by exploring all kinds of alternatives. The experts I talk to are--and I'm certainly not one--say it's a question of doing a lot of little things that amount to a big thing, like building more energy efficient buildings, even in developing countries. It actually ends up saving people money because they are not consuming as much energy. Energy still costs something. Migrating away where it's practical from fossil fuels toward renewables. So there are some parts of the world, including Africa, where it actually makes sense to have a supplemental supply. Can't do everything with solar power, or maybe wind. I'm a big proponent, I get into lots of trouble with my colleagues over this, but like John, I'm a big proponent of nuclear energy. I'm so tired of being told we can't do it. France went from almost no nuclear to 80% nuclear in 15 years. Are you seriously telling me that the United States can't do, cannot do, what France did? I don't think so. There's one other piece of technology which would allow us to burn at least natural gas as much as we want to, if we could only get there, which is to capture the carbon from the atmosphere and sequester it. And I think it makes a lot of sense to put some money, not to jeopardize the economy, but some research and development money, into trying to develop this technology to the point where it might some day make economic sense to do that. We are not that far from being able to do it even today. So these are sensible things. We don't have to bet the farm. We just do sensible things.

52:30: Both, surprisingly to me, were very down on geo-engineering.
At 53:25, Emmanuel says why: Someone, even an individual, might get the technology to geo-engineer.

55:30: Roberts asks if either of the guests is ever embarrassed by people on his side. They both answer emphatically yes.

1:01:00: Advice on what to read on climate.
1:01:25: Emmanuel says don't read blogs on climate science. Read good books about the physics of climate.
1:03:20: Christy says read Congressional testimony of scientists--not of advocates or politicians, but of scientists.

Comments and Sharing

COMMENTS (6 to date)
J Scheppers writes:

I am both hopeful and pessimistic regarding how the interview went. Clearly rational discussion with enough good will to try to hear the other point of view, along with addressing the issues raised by your debating counterpart is a great thing.

However, our regulatory and legislation making organization virtually never follow this reasoned approach. Legislation is much more "power" market based, and regulation is much too idealistic regarding what can be done.

Please pardon a digression while I try to make a point. As I was listening to a different Econtalk podcast, I had an epiphany. Dr. Roberts was discussing agriculture subsidies and they were talking about what would happen to farmers if they were ended. The amazing thing that I realized was that not all the subsidy is wasted. In fact if the regulators had subsidized perfectly there would be no change in the value to system. On the other hand, farmers without a subsidy would simple charge more. The ag consumers would no long pay the subsidy and instead pay that same subsidy amount added to the original price for ag products.

The reason to end subsidies is not to think the full subsidy will be recovered, but rather the subsidizing regulations are far less efficient than market determination of values. The complete value of eliminating subsidies is in the knowledge gained from the market. The market is not perfect but simply empirically better than regulators.

How does this apply to climate management? Today, based on our market knowledge we know there could be climate damage. Those signals of potential damage are real market forces that are causing market actions. It is incorrect to say that carbon emissions are not priced. Coastal residents and their descendants face insurance costs and property valuation that change with the risk due to hurricanes and sea level rise. Farmers face crop risks and food valuations just the same from drought or excess rain. Clearly some price is being paid by tax payers in the insurance subsidies that go to both the coastal residents and the farmers. It is doubtful that added government determined price will do better than the market. The one thing that may do the most is to assess how to assign the property rights of climate changes to best enable a better approach than today’s market.

I suggest the best solution to climate management will come from market determination of the price. Assignment of liability of possibly half the increased risk substantially related to climate change could be one of those improved property rights. But that does not mean we need a regulator to determine the price. The best means of determination of the price is to restore the climate damage recipients of their obligations to pay for both current risks and half the increased risk from climate change.

Placing the full responsibility on the carbon emitters is to invite the placement of hay bales next to the train tracks to hopefully catch fire from the know externality of the sparks coming off the train. (I think this is general concept of example Coase used to address Pigovian externalities.) In any case there is no need for the government to determine the price now, only to establish the liabilities and mechanism to ensure proper payment in the future.

Robert Schadler writes:

Frank Knight provided a useful framework for this issue (and many others) in Risk, Uncertainty and Profit, nearly a century ago. Risk is what we know enough about that insurance can be applied through calculating the odds. Put differently, things about which predictions can reliably be made. Uncertainty is about future possibilities about which the odds cannot be reliably calculated.
It seems here that there are plenty of predictions (which is the easy part); but those predictions are not yet reliable (the hard part).
Just because a scientist, or lots of them, think something will happen does not make it a reliable prediction.

Brian writes:

The excerpts of the interview, which I have not had time to watch, are interesting. I'm glad to hear that Christy and Emmanuel were civil and reasonable. I do object, however, to statements made by both of them. The objection is not that the statements are false, but that they give a false impression by what they did not say.

Christy @ 29:55

"I know of no one who predicted a flat temperature trend for the past 15, 16, 17 years. We were all under the belief--me, included--that CO_2 forcing would cause even more warming."

Lot's of people on the skeptical side have been claiming for at least a decade now that temperatures would flatten out or even go down. The reason is that the sun was expected to be less active (it has been, but this may or may not impact climate change) and the natural cycles of the AMO and PDO have favored less warming over the last 15 years. Variations in temperature rise, including the slow down between 1945 and 1975, have closely tracked these cycles over the last 150 years. The cyclic nature of the temperature rise is so obvious that no one looking objectively at the data can deny it. Given this, the pause (or at least slower temperature growth) is expected through 2030, before picking up again. All of this has been known and talked about in skeptic circles for years, so Christy shouldn't act as if it's unexpected.

Emmanuel @ 40:50

"the best estimates from the last IPCC (Intergovernmental Panel on Climate Change) reporter on the order of a meter or so--3 feet by the end of the century. But everybody who is in that business says there is much more uncertainty about that than anything else."

Sea-level rise over the last 150 years has averaged less than 2 mm/year and it is currently averaging less than 2 mm/yr. The data suggest two things--sea-level rise is on track to rise a mere 7 inches over the next century, a miniscule amount, and there's no evidence of a long-term acceleration of that rate. It's safe to say, regardless of the uncertainty, that a 1-m sea-level rise by 2100 is impossible. Not improbable, but impossible. There is no physically plausible mechanism that is capable of melting enough land-based ice or warm the ocean enough to create a 1-m rise.

The problem, in my opinion, is that the global warming meme has seeped so deeply into scientific minds that even lukewarmers like Christy find it difficult to identify which facts are relevant and which are not.

David R. Henderson writes:

Thanks for these thoughts.
So you would also criticize Emmanuel on the pause point too, right? Recall that in the post above, I quoted this:
Roberts: Does the Pause give you pause? You were confident that there is a small chance of a large rise, based on the rough science and some of the models. Does it cause you to be a little more conservative?
Emmanuel: Well, no. Not really. I think that range [2.5 to 9 degrees Fahrenheit] was generous enough that I would stick with it, until--maybe if we had 30 years of Pause. That would give me pause.

Of course, that would have taken us to 2029, essentially the same as your 2030.
Interesting point about sea level rise. If you could provide a cite to this, I would be most appreciative.

Brian writes:


I agree that the pause should make him more conservative. There's no chance of a 4 C rise by 2100, if that's what he was referring to. But his correct point is that the range is so large that data will be hard pressed to change anyone's priors.

About the sea-level rise, I am supplying the reference and the abstract. Please note that even the IPCC AR5 states that sea level has risen 1.7 mm/yr since 1901. They do claim an acceleration to over 3 mm/yr since 1993. The paper I am giving you acknowledges that acceleration, but shows that it was a short-term effect. A very slow acceleration of 0.02 +- 0.01 mm/yr^2 has been going on for 200 years and cannot be attributed to anthropogenic climate change. Also note that the rate since 1970 is identical to the rate seen over the 20th century, indicating no acceleration due to anthropogenic climate change.

Here's the paper:

Trends and acceleration in global and regional sea levels since 1807. Global and Planetary Change 113: 11-22. Jevrejeva, S., Moore, J.C., Grinsted, A., Matthews, A.P. and Spada, G. 2014.

We use 1277 tide gauge records since 1807 to provide an improved global sea level reconstruction and analyse the evolution of sea level trend and acceleration. In particular we use new data from the polar regions and remote islands to improve data coverage and extend the reconstruction to 2009. There is a good agreement between the rate of sea level rise (3.2 ± 0.4 mm•yr− 1) calculated from satellite altimetry and the rate of 3.1 ± 0.6 mm•yr− 1 from tide gauge based reconstruction for the overlapping time period (1993–2009). The new reconstruction suggests a linear trend of 1.9 ± 0.3 mm•yr− 1 during the 20th century, with 1.8 ± 0.5 mm•yr− 1 since 1970. Regional linear trends for 14 ocean basins since 1970 show the fastest sea level rise for the Antarctica (4.1 ± 0.8 mm•yr− 1) and Arctic (3.6 ± 0.3 mm•yr− 1). Choice of GIA correction is critical in the trends for the local and regional sea levels, introducing up to 8 mm•yr− 1 uncertainties for individual tide gauge records, up to 2 mm•yr− 1 for regional curves and up to 0.3–0.6 mm•yr− 1 in global sea level reconstruction. We calculate an acceleration of 0.02 ± 0.01 mm•yr− 2 in global sea level (1807–2009). In comparison the steric component of sea level shows an acceleration of 0.006 mm•yr− 2 and mass loss of glaciers accelerates at 0.003 mm•yr− 2 over 200 year long time series.

David R. Henderson writes:


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