Judith Curry on Climate Change
Dec 23 2013

Judith Curry of the Georgia Institute of Technology and blogger at Climate Etc. talks with EconTalk host Russ Roberts about climate change. Curry argues that climate change is a "wicked problem" with a great deal of uncertainty surrounding the expected damage as well as the political and technical challenges of dealing with the phenomenon. She emphasizes the complexity of the climate and how much of the basic science remains incomplete. The conversation closes with a discussion of how concerned citizens can improve their understanding of climate change and climate change policy.

Explore audio highlights, further reading that will help you delve deeper into this week’s episode, and vigorous conversations in the form of our comments section below.


Dec 23 2013 at 10:39am

The trouble starts not with the complexity of the vast system, but that we have no information at all about anything.

1. You can’t tell a cycle from a trend with data that’s short compared to the cycle. (The eigenvalues of the distinguishing matrix explode making every observtion useless for the purpose.)
So there’s no data at all.

2. You can’t model even just the atmosphere because you can’t solve the Navier Stokes equations (in 3D flows go to shorter and shorter scales, making every computer resolution inadequate for a numerical solution. But you need short scale flows because they act as a kind of ersatz viscosity back on large scale flows).
So there’s no theory at all. You don’t get to substitute an equation that you can solve for the correct one that you can’t.

When you have no information, don’t try to fix it.

The space of unobserved problems is huge. There’s no precautionary principle that doesn’t overspend on the imagined problem.

Just speaking as a former solver of hydrodynamic problems and a former signal processing guy.

It’s how I know, am certain, that the scientists don’t know what they say they know.

Then I wonder why they’re doing that.

We don’t know that the earth isn’t warming, either. It’s a problem that we can’t know about.

One thing we do know is that the earth has been through huge cycles in the past, which itself is evidence of climate stability. It didn’t run off to one extreme or another.

That ought to answer the feedback question in the non-alarm direction.

Dec 23 2013 at 11:15am

Re: Climate model taxonomy.

You can prove that climate models are curve-fitters, if you’re familiar with Kalman filters.

The Kalman filter formalism tells you how to change the knobs when new information comes in, so as to best match the information.

It amounts to least squares but the formalism lets you notice that climate models follow the same procedure. They adjust the knobs so as to match new “past” data.

That doesn’t improve predictions! It only improves the past fit.

Think of all climate models as polynomial fits. They all exactly fit all past data. Tomorrow’s prediction is complete garbage, because the climate isn’t the polynomial.

Just as the climate isn’t the model.

Kalman filtering is useful in pretty simple cases, where the model and reality are pretty close. Then the predictions would be good.

Dec 23 2013 at 5:01pm

rhhardin – I hope that you will, if you have not already, check out Climate, etc. I think you might enjoy the debate there.

Geoff Harris
Dec 23 2013 at 5:55pm

Russ, I am disappointed by your lack of proper questioning of Dr Curry.

That you don’t know enough about climate science to spot all her well-debunked skeptic talking points and straw-men is perhaps not your fault. But on the other hand perhaps it is when dealing with a controversial subject. You should know that she is not in the mainstream of climate science and has a reputation for misrepresentation. For more information, you or your listeners might visit the Skeptical Science website and Source Watch.

On economics you surely have the nous to question here properly. But despite years of experience as an economist you didn’t even push her on whether a carbon tax, despite not being a cure-all, would at least slow down the damage being done. And how can you not point out that to compare clean energy and dirty energy, you must look at the whole story. You let her get away with,

“… if clean, green energy is the same price as dirty energy, I think people would naturally prefer to use the cleaner source of energy. … But they don’t want to sacrifice the abundance or the ready availability of the energy; and they don’t want to pay too much more for it.”

without questioning the whether that dirty energy is really cheaper. Here’s a hint, it is in the name “dirty”; think externalities. There are many “skeptics” who refuse to admit that fossil fuels have costs that the end user doesn’t pay, but I have trouble believing that any economist can be so blinded.

I find it hard to avoid concluding that you just threw Curry some soft balls to hit that corresponded to your own preconceptions of climate science. Hey you even let her rabbit on about academic standards as if what she discussed is not a commonplace in your own field or any other field of research. Really, you have gone down in my estimation.

Dan Pangburn
Dec 23 2013 at 9:13pm

The net effect of all ocean oscillations, named or not, causes the average global temperature to oscillate above and below the temperature trend calculated from the time integral of sunspot numbers.
Natural climate change has been hiding in plain sight. Simple equation calculates temperatures since before 1900 with 90% accuracy (95% correlation) and reasonable estimates since 1610. http://agwunveiled.blogspot.com/. CO2 change had no significant influence. The average global temperature trend is down.

Dec 23 2013 at 11:08pm

A great “cool air” presentation of this heated debate. Ironically this debate over “hot air” features much of it on both sides. When rhetoric is so extreme and emotions are so powerful, the general public loses out. Tribal-like responses only serve to alienate people.

This podcast reminds me of the importance of quality media. No, we’ll never have a purely objective sense of what is going on. This inability, though, is not a reason to disregard the issue. More podcasts like this would do quite a bit to help educate the public on this issue and work to collect the added intelligence that this public can provide. Emotion won’t protect us here.

Dec 24 2013 at 6:51am

An honest, thoughtful, wise guest. It’s depressing to hear how politicized science, or at least some branches of it, have become. But I guess there’s nothing new about the mixing of politics and science, as Galileo would attest, if he could.

Victor Venema
Dec 24 2013 at 7:55am

rhhardin writes:

1. You can’t tell a cycle from a trend with data that’s short compared to the cycle.

If you are talking about the temperature trend over the last decade you are certainly right. Do you also see “cycles” as explanation for the temperature trend of 0.8°C per century since 1880? Do you have any idea why these large cycles were not visible before?

If a deviation is so large, you can no longer say, it is just a cycle, you will also need a physical explanation. For variability of a tenth of a degree at the scale of a decade you can say that is is impossible to determine the cause. Then you may call it natural variability or internal variability due to small and hardly measurable changes in the circulation of the oceans, atmosphere, cryosphere and vegetation. However, for 0.8°C over a century you need an explanation, the cause of that should be determinable.

Personally I would say that it is mainly due to greenhouse gases and thus not a cycle.

Dec 24 2013 at 10:41am

A good podcast. A couple comments though.

1) Ignoring prediction models and given what we currently know, why still no pressing need to cut carbon emissions? There seems to be something more to it than skepticism.

2) There is more data supporting anthropogenic climate change than there is to support the model that says increasing minimum wage would decrease employment. So why the resistance to policy for the former while saying hands off on the latter?

I wrote something in the similar vein to this podcast titled “Why Hurricane Season Predictions Are Bad for the Environment” with a hat tip to the Pindyck episode.

[Comment edited with permission of commenter–Econlib Ed.]

John Russell (Twitter@JohnRussell40)
Dec 24 2013 at 11:04am

rhhardin wrote:

“One thing we do know is that the earth has been through huge cycles in the past, which itself is evidence of climate stability. It didn’t run off to one extreme or another. That ought to answer the feedback question in the non-alarm direction.”

It is, of course, true that the Earth has been through huge climatic cycles in the past. Everyone knows and understands that: it’s why we are able to anticipate where the current man-made climate changes are likely to lead. However, in the 10,000 years since humans gave up the life of nomadic hunter/gatherers, being pushed around by the prevailing conditions, and settled down to farm, the climate has been relatively stable. So concern about climate change is not about whether we’ll tip the planet into an extreme life-threatening phase, but whether we can ensure we don’t change it to the point where it disrupts society enough to threaten civilisation.

The bottom line is that CO2 has been below the 300ppm level of atmospheric concentration for all the time homo sapiens and our immediate ancestors have walked the planet. Now we’ve pushed it to 400ppm and rising and global temperatures are trending upwards, ice is melting, weather is becoming more extreme and sea level rising as proof.

We’re carrying out a global experiment. To deny this is dangerous.

Victor Venema
Dec 24 2013 at 11:54am


… the thing that comes to my mind as an economist is the way some macroeconomists talk about stimulus spending or government spending: we just need to–or of the money supply depending on what flavor of economist you are–we just need to tweak this variable; we have a control knob, they tell us.

The discussion about the “hiatus”, that the surface air temperature is not growing as fast in the last decade as it used to, could be compared to the discussion about stimulus spending and government spending. That discussion is about the short-term changes and about deviations very small compared to our wealth or the total temperature change. The dynamics for these short-term fluctuations is difficult and many factors can play a role.

The question whether the long-term temperature is changing due to human emissions is greenhouse gasses is better compared to what we know about long term economic growth. Just as it is not controversial in economics that the rule of law or having certain private property rights is good for growth, it is not controversial that greenhouse gases warm the atmosphere in the long run.

Except that the basic relationship between greenhouse gasses and temperature is pure physics and that thus the existence of the relationship has a certainty that can not be achieved in economics. The confidence interval for the strength of the relationship is mainly determined by feedbacks in the climate system. How strong these feedbacks are, is difficult to determine as we take the system into an unprecedented state. Surprises, unknown unknowns cannot be excluded.

The confidence interval can be computed in three ways: using historical measurements (paleo climatology and recent man-made global warming) and global climate models.

Dec 24 2013 at 2:14pm

@John Russell

The fact of cycles proves that the system opposes perturbation. It doesn’t have any purely growing mode or it would have turned up.

The question of positive feedback is supposed to make the minor greenhouse contribution amplify into something worrisome owing to what it feeds back into.

The geologic cycles show there’s no such positive feedback.

That’s an experiment run with the actual climate.

An unstable mode will turn up on its own if there’s one there, because it grows exponentially even if excited very little at the start.

I’m not climate guy but my checkered career has a few points of contact with the supposed physics here, and it’s not coming out well for the warming alarm side.

Victor Venema
Dec 24 2013 at 4:01pm

rhhardin writes:

“It doesn’t have any purely growing mode or it would have turned up.”

Sounds like a strawman to me. Did anyone claim that the climate system is unstable and that any temperature rise would amplify to infinity? At least John Russel certainly did not.

What is called a positive or negative feedback in climatology are changes in the climate system that make the initial response to the forcing (e.g. greenhouse gasses) stronger or weaker.

In the end, the increase in temperature leads to increases in heat radiated to space. That is a strong negative feedback that prevents a run away of the temperature. Just like in reality in the end always a negative feedback kicks in.

Nathan Beckmann
Dec 24 2013 at 4:52pm

I was also disappointed in this podcast, particularly the discussion surrounding clean and dirty energy. It seemed to me that the guest was arguing against regulation that would force a shift to renewables, but that is not what most intelligent commentators are in favor of. In fact, this is the entire purpose of a carbon tax, as I’m sure Russ understands — nudging the market towards renewables by incorporating the full costs of fossil fuels. A carbon tax would not force any market participant into renewables, yet this seems to be the strawman that Dr. Curry was arguing against.

I also have a deeper philosophical objection to the discussion. I admit that we are unable to model complex processes exactly, and that any “pretense to knowledge” of exact outcomes is arrogant and certainly false. But that is not the same as knowing nothing, and we can understand general trends without being able to make numerically precise predictions.

Therefore one can fully justify a policy like a carbon tax qualitatively and scientifically. This would be the end of the argument were it not for the practical problem of setting a price — what should the carbon tax be?

This purely practical consideration forces climate scientists to put numbers to a scientific theory that, in all rights, should probably remain qualitative. (This is a very analogous situation to macroeconomics.)

Yet Russ made the argument against doing so on the grounds of “do no harm”. I’m unconvinced on scientific as well as moral grounds, and it seems a particularly strange objection for a professional economist to make.

First, as I said before, although we can agree that quantitive predictions are unscientific, it does not mean that the qualitative predictions are unscientific. That is, we don’t know nothing, and letting the limits of our knowledge prevent any action is simply letting perfect be the enemy of good. It is not scientifically justified.

Second, we should recognize that doing nothing is itself a policy choice. Inaction has no moral superiority on its own merits. “Do no harm” is, to my way of thinking, simply passing the buck and absolving oneself of moral responsibility without cause.

The real philosophical issue with translating climate science into public policy seems to me the conflict between the real costs of government intervention in the market and the real costs of climate change. Both are well established qualitatively but not so much quantitatively, and in this case the costs point in opposite directions — the former argues against climate change public policy, the latter argues in its favor. So we’re back to the practical matter of predicting these costs qualitatively to decide what to do, which leaves plenty room for different predictions (without saying every opinion is equally good).

To summarize, we shouldn’t be paralyzed by a fear of doing harm. We should take the best actions we can, recognizing the limits of our knowledge and with humility. But waiting until the costs are so large as to be undeniable is not the best path forward, nor is it scientific.

Dec 24 2013 at 5:08pm

When I heard 1998, I knew I was in for spin.

1998 was way, way above trend, well above nearby years. Choosing that window is a little like saying that stocks are a horrible investment because the market collapsed during the Great Depression.

Don Rudolph
Dec 24 2013 at 5:34pm

I am not sure how I stand on the climate change debate. I tend to go along with the expert consensus when I lack enough information to make a decision. When the word denier is used I assume it refers to “holocaust deniers”. In that topic as well as this I look at the interests of people making the claim. If you claim there is not a strong case for global warming I wonder if you are bank rolled by industry. If you say there was no holocaust I wonder if you belong to a anti-semetic group. Why do people feel the need emotionally to get on one side or another of this debate. I think humans decide most things for unstated emotional reasons rather than reason.
How much evidence is required for action to be taken. We might say there is not enough evidence to ever take an action of any kind. I have noticed my wife will say she is sure of a thing when she is 51% sure while I pause at 90%.

Don Rudolph

Dec 24 2013 at 6:35pm

Geoff Harris wrote, in part …

You should know that she is not in the mainstream of climate science and has a reputation for misrepresentation. For more information, you or your listeners might visit the Skeptical Science website and Source Watch.

From Skeptical Science …

So, what the heck is a climate model? [ … ] For people who aren’t scientists, it is best to think of them as virtual-reality computer programs that predict the future.
[ … ]
The reason scientists spend so much time using models is because they allow us to make future predictions that are testable. Climate models can predict cooling of the stratosphere, they can predict loss of arctic sea ice, they can predict changes in weather patterns, they can predict acidification of the ocean; climate models can be used to study what if scenarios in a way that our other information sources cannot. In fact, computer models have an excellent track record predicting changes in the Earth’s climate before they were detected by measurements. In this way, measurements have confirmed climate models.


Dec 24 2013 at 8:40pm

Trust us, we’ve got a model!

Dec 25 2013 at 12:40am

Currently, according to the CDIAC, China and India combined produce about 2x more CO2 emissions than the U.S., and are projected to produce much more (exponentially) in the next few decades as these developing nations “catch-up” to the U.S. Richard Muller made a chart that shows that if China were to cut back by 4% of their growth intensity (as outlined in the Copenhagen proposal) and we were to drastically cut back ours…our emissions would be dwarfed by theirs by a magnitude of 20x or more.

Seems really silly to get our panties in a bunch over our own emissions and take steps that would definitely curb our economic growth when the main perpetrators of a supposed dangerous greenhouse atmospheric gas dump are free to do so with impunity. It’s as if, as Muller puts it, we think we can solve world hunger by giving some bum 50 cents instead of 25.

The near religious fanaticism of climate alarmists makes it really hard to listen to them and not wonder if their bias makes their reasoning flawed. The underlying fear of Gaea delving into some irreversible death spiral eventually creeps into most threads. Having discussions about global warming without getting into doomsday scenarios (like the Himalayas melting, Thailand being the new Atlantis, Polar Bears disappearing, snow in England being a thing of the past, extreme weather, extinct species, etc..) would be a nice, but it doesn’t happen much.

Couple the paranoia with the hypocrisy of carbon offset advocacy and you can see how truly muddle this debate really is.

Brian H
Dec 25 2013 at 4:42am

Edit: Curry: “it would be about 2-3 degrees Centigrade per decade of warming”. Per century.

And even that is likely an order of magnitude too high. Wassamata with warming, anyway? Civilizations and Nature both seem to prefer it.

Geoff Harris
Dec 25 2013 at 6:49am

Russ, the issue of a carbon tax reducing growth often comes up in discussions of global climate change. Climate science “skeptics” often portray it in catastrophic terms, such as “destroying the economy”. Does economics really hold any solid evidence that paying the full costs of ones actions damages the economy in the long run?

I can see that if all of the externalities associated with fossil fuel extraction occur in other countries (think pollution, environmental destruction, corruption, suppression in addition to climate change) then it might be the case narrowly in your own country that a tax might have some effect (but even then I’m not sure it would not just increase the efficiency of resource use). But if some or all of those externalities occur closer to home (which they assuredly do), is there evidence?

By the way, I mean solid evidence, not just opinion.

Dec 25 2013 at 7:43am

For those justifying a carbon tax based on negative externalities …

Why Global Warming Would be Good for You
GLOBAL WARMING: A Boon to Humans and Other Animals


Dec 25 2013 at 9:45am

David wrote, “When I heard 1998, I knew I was in for spin.”

Spend a few minutes with the temperature trend viewer that Nick Stokes maintains at moyhu and decide for yourself what the Global Mean Surface Temperature has been doing. Spin for yourself.


Nick Stokes is “An Australian scientist (not climate) with an interest in the climate debate.” An interesting aspect of global warming skepticism is the number of highly educated, trained and experienced people from outside climate science that take a serious and deep interest in the subject. They bring experience in modeling, statistics, math, chemistry, physics, law and politics to the discussion because they see the same problems Judith Curry talked about.

And they do it for free. Citizen Scientists.

Dec 25 2013 at 11:39am

@Victor Venema

If you are talking about the temperature trend over the last decade you are certainly right. Do you also see “cycles” as explanation for the temperature trend of 0.8°C per century since 1880? Do you have any idea why these large cycles were not visible before?

The need for data not short compared the cycle to be excluded in favor of a trend is dimensionless. It applies to any duration. It’s just math that any engineering graduate student can do. The eigenvalues blow up.

Think of how many derivatives you have to determine to tell something is not part of a larger cycle, to develop an intuition. Each successive derivative is noisier than the last, and you need them all.

It’s how the uncertainty principle imposes itself on signal processing. An eigenvalue explosion.

You can beat it with a large signal that overwhelms the eigenvalue explosion. See for example “supergaining.” But there’s no large signal here. It’s mostly all noise, and the noise gets amplified by the explosion.

Greg McIsaac
Dec 25 2013 at 12:30pm

I’ve learned some things from reading Judith Curry’s blog postings for the last year or so. Because she has a depth of relevant knowledge on the subject, I think her perspective is often a useful counter point to those who gloss over uncertainties and complexities.

In this discussion, on biofuels, she was not very specific, but I suspect she was referring to corn starch based ethanol. She can say that there is little if any reduction in greenhouse gas emissions from this because there have been a large number of scientists who have examined it skeptically. Furthermore, reducing greenhouse gas emissions was not the only intent (and perhaps not a primary intent) of the Renewable Fuel Standards. It was originally promoted as a effort to reduce dependence on imported petroleum. And of course these initiatives are influenced by politics.

For informational resources, I think the climate.gov web site is more up to date and comprehensive than the EPA web site. Within the federal government, NOAA, NASA and DOE all do research on climate change, and climate.gov attempts to provide some integration. The National Academies of Sciences also has a web site devoted to climate science and policy

Christopher Hinton
Dec 25 2013 at 3:25pm

This simple minded Joe remembers a day when he could play hockey on an outdoor pond, and yachts had trouble sailing through Arctic seas.

It seems to me that if I follow the ideas of Judith Curran I would never upgrade my computer again, it being a massively complex decision with unpredictable social, economic, and spiritual consequences that could lead to real harm.

When in the entire history of humanity did we ever get it right? Science will never nuance the equation and reach consensus. We can only make adjustments and react to those adjustments and hopefully get the process started for the next generation.

To do nothing at all is wicked.

Dec 25 2013 at 4:37pm

@Christopher Hinton

It seems to me that if I follow the ideas of Judith Curran I would never upgrade my computer again, it being a massively complex decision with unpredictable social, economic, and spiritual consequences that could lead to real harm.

If you upgrade, your programs stop working.

Busy graduate students have been working at redefining the language so that what used to be legal is no longer legal.

Graduate students are the elite in this system.

The solution is stay with XP, for example.

The great thing about owning your computer is that you get to say what changes, mostly nothing; instead of the local IT guy deciding to ruin things once a year.

Dec 25 2013 at 5:04pm

To do nothing at all is wicked

It seems to me this is only true if doing something leaves us better off than doing nothing. If global warming is not going to cause problems in the future then making people less well off now in order to solve a non-problem seems wicked to me. Especially since the ones who really suffer will be those who are already less well off.

Dec 25 2013 at 5:17pm

What is called a positive or negative feedback in climatology are changes in the climate system that make the initial response to the forcing (e.g. greenhouse gasses) stronger or weaker.

This brings up something I have wondered about for awhile. My understanding is the feedback is due to the warming caused by the forcing which causes more warming. If this is true then wouldn’t you get positive feedback from any warming? If so, why didn’t we get run-away warming from the warming trend from the 1850’s to 1940? If other factors prevented the warming from increasing due to positive feedback during that period why won’t those same factors prevent excessive warming in the future?

Dec 25 2013 at 5:29pm

Except that the basic relationship between greenhouse gasses and temperature is pure physics

My understanding is there is no disagreement about the physics of greenhouse gasses causing some increase in temperature if everything else is held constant (which never happens in nature). I believe the physics also show the effect of greenhouse gasses is logarithmic so the majority of the warming directly due to greenhouse gasses has already occurred. Going from 200 ppm to 400 ppm causes more warming than going from 400 ppm to 600 ppm.

The question is how much positive feedback is there to increase the warming effect and that is not a basic physics question because climate is a mathematically chaotic system which makes it extremely difficult to model and which means if the model is slightly off in the beginning it may result in large errors in future predictions. As was pointed out earlier no one is claiming the warming will increase to infinity so the question is if there is positive feedback when does the negative feedback become dominate? Also, we know there are some known benefits to increased warming and CO2 so will the negative feedback take control before the net effect of warming and CO2 is negative?

Dec 25 2013 at 5:59pm

I very much enjoy Econtalk and Mr Roberts’ respectful and thoughtful treatment of his guests. However, I thought there were two glaring mistakes Russ made in this episode:

1) Modeling a complex scientific problem is NOT analogous to modeling economies. Millions of rational and irrational (and hence, more unpredictable) decisions constitute inputs to modern economies. While also complicated and not fully understood, climate models address natural systems which follow known natural laws. Humankind’s success in understanding these laws and forecasting their impacts is far superior to the same in the realm of Economics.

2) The “normal” fluctuations in climate are important, and for the most part, they are outside of the influence of humans. Carbon dioxide and other greenhouse gas emissions, are, however, somewhat within our control. To take one example, the dominant contributor to the temperature of the earth is solar output. To the extent we are experiencing very slightly lower solar input over the past decade or so is little comfort given that it is likely this variable reverts to the mean soon. CO2 concentrations of >400PPM, however, will not. We must focus on what we can (possibly) do something about.

Dec 25 2013 at 6:13pm

While also complicated and not fully understood, climate models address natural systems which follow known natural laws. Humankind’s success in understanding these laws and forecasting their impacts is far superior to the same in the realm of Economics.

This is an interesting claim. Is there any research comparing the accuracy of GDP predictions vs Climate predictions at different time intervals? Also, what we really care about is climate, not temperature. None of use could tell the difference between a 20 and 21 degree Celsius day. How accurate are climate predictions 1-5 years out? Can they predict amount and locations of rain, snow, storms, clear cloudy, etc?

Dec 25 2013 at 6:45pm

climate models address natural systems which follow known natural laws.

That was one of my complaints. They don’t and can’t use the known natural laws even for laws that they know.

The equations are too hard to solve.

Aeronautical engineering solves the Navier Stokes equations by replacing them, but they also have an expression “outside the envelope.”

This refers to a place where they haven’t verified the model against real data.

They don’t use model data outside the envelope without verifying it against reality in aeronatical engineering.

Not so in climate models! They use nothing but computations outside the envelope.

That’s quite a difference in science procedures.

So climate science is more like economic modelling than you imagine.

Dec 25 2013 at 8:53pm

Boeing knows a lot about aerodynamics and modeling airplane performance. But they still performed 15,000 hours of wind tunnel tests during development of the 787.


Climate modelling is an immature science with no way to verify models other than waiting. And right now it looks like the majority of the models used by the IPCC are running too hot.

Dec 26 2013 at 4:53am


I believe the physics also show the effect of greenhouse gasses is logarithmic so the majority of the warming directly due to greenhouse gasses has already occurred. Going from 200 ppm to 400 ppm causes more warming than going from 400 ppm to 600 ppm.

True enough, but it’s important to remember the time frame for the response. Roughly 1/2 of the response is over a few decades (fast response), with a slow response that saturates over a few thousands of years.

Geoff Harris
Dec 26 2013 at 8:24am

Saying that models “don’t and can’t use the known natural laws even for laws that they know” is misleading. Quoting from Nasa’s Gavin Schmidt (The Physics of Climate Modeling),

The physics in climate models can be divided into three categories. The first includes fundamental principles such as the conservation of energy, momentum, and mass, and processes, such as those of orbital mechanics, that can be calculated from fundamental principles. The second includes physics that is well known in theory, but that in practice must be approximated due to discretization of continuous equations. Examples include the transfer of radiation through the atmosphere and the Navier–Stokes equations of fluid motion. The third category contains empirically known physics such as formulas for evaporation as a function of wind speed and humidity.

The first category will be used. The second two will also be used but as approximations. The success of the models will clearly depend partly on the quality of the approximations, but to say the natural laws are not used is a step too far.

Dec 26 2013 at 10:25am

The second includes physics that is well known in theory, but that in practice must be approximated due to discretization of continuous equations. Examples include the transfer of radiation through the atmosphere and the Navier–Stokes equations of fluid motion.

It’s not an approximation to NS in the sense that it converges to the solution if you make the discretization finer, which would be the usual criterion for a differential equation. The error here does not decrease with refinements in grid size.

Typically they just substitute another equation that isn’t the right one. Look for a term named “effective viscosity” for instance.

That’s why it needs a reality check. But reality check isn’t part of the climate science culture, unlike aeronautics. It’s more into publishing.

The physics groups I’ve worked in tended to have a models crowd and a fundamentals crowd. The latter were more interested in the work as a hobby, the former were more into a career path.

Dan Pangburn
Dec 26 2013 at 10:42am

The science is settled. CO2 change has no significant influence on average global temperature.
The ‘time integral of sunspot numbers’ acceptably explains the average global temperature trend since 1610. When combined with the net of ocean cycles, the calculated average global temperatures since before 1900 match the actual measured with 90% accuracy.

Dec 26 2013 at 12:20pm


True enough, but it’s important to remember the time frame for the response. Roughly 1/2 of the response is over a few decades (fast response), with a slow response that saturates over a few thousands of years.

Doesn’t this mean the warming is from the CO2 already emitted is going to happen over the next 1000 years whether we reduce emissions now or not?

Steve Sedio
Dec 26 2013 at 3:38pm

Like RHHardin, I have done my fair share of modeling. “Climate” is orders of magnitude more complex than systems we can’t yet model accurately (the path of a hurricane, for example).

Even if we could model climate, and proved CO2 was causing warming, what do we do? We have no suitable alternative energy sources, today.

Solar is limited to 5 hours a day (until we orbit hundreds of square miles of mirrors), and we have no suitable storage for electricity (those miracle batteries we hear about every couple of months – never materialize).

Biofuels look good for transportation fuel (algae and Jatropha are close), but, they are far from CO2 neutral.

Other than that, there is a patchwork of minor sources, many incompatible with our existing infrastructure.

The question should be, who made this a political battle? And, why?

Judith Curry
Dec 26 2013 at 8:15pm

I have read with interest all of your comments. If you are interested in a dialogue on this topic, I encourage you to check out my blog Climate Etc. judithcurry.com

John Berg
Dec 27 2013 at 2:10am

Returning to the storage of solar energy:
As I learned from econtalk.org some time back, actually the use of fossil fuel like coal, gas, and oil is using solar energy stored from some time back. And I recall another natural cycle of CO2 to O2 to CO2 commonly found in nature all around the globe. I also recall from the 1960’s Scientific American Input/Output table of commerce, these fossil fuels (and their long carbon chains) were also used for fertilizer, drugs, and plastics.

Dec 27 2013 at 10:27pm

I find it interesting that so called free market economists and pundits are quite often anti science. It is fun to google Russ and read what he has written about global warming and science.

Do you still think all the climate scientists are part of a big hoax Russ. Do you still think they are trying to fool everybody just to get founding? You said so in 2007.

Do you think Cato should be taken serious in this debate (remember their founding)?

Matt Barton
Dec 27 2013 at 11:37pm

@ Halvard:

You suggest that those who favor freedom are “anti science”… This is nonsense – no one denies the importance of scientific investigation… It just has to has to used when sufficient knowledge about basic facts makes it meaningful… The “Fatal Conceit” of Scientism and its corresponding abuse of reason is that to which the Classical Liberal objects…

Dec 28 2013 at 5:21pm

A very good talk, thanks … What alarmed me is her assessment of the state of the science today – there is so much money to be made by running models and making bold economic predictions about what will happen 100, 200 years hence – that there is very little time being spent on fundamental issues – the complexity of the atmosphere and the oceans and the role of the solar cycles and so on …

Leaving the “climate scientists” alone for a minute, a bigger villain who has cause enormous harm is Justice Kennedy – He wrote the majority opinion (5-4) in EPA v Massachussets that “concluded” that CO2 is a pollutant and so the EPA can regulate it – It is further proof (for me anyway) of the abysmal state of science education in general and the oversized roles scientifically illiterate and ignorant lawyers are playing in our economy

The fact that even as CO2 has been increasing and has NOT resulted in increasing temperatures the past 15, 20 years should be a reminder for a true scientist to stop and assess his/her model – but we need to remember that this hate towards CO2 is not about “Climate” per-se, but about industrial development in general – and as poor countries are discovering that the secret to their growth is energy production and distribution, these CO2 warriors are panicking – because energy production and use will increase – and cause people to expect more of their lives.

Russ Roberts
Dec 28 2013 at 6:24pm


I’d like to say that you quoted me out of context but that would be inaccurate–you didn’t even quote me. Interested readers can read what I wrote here. The point of that post (from 2007) was to predict that little would be done about global warming and why I thought that would be the case. So far, I’ve been right. In passing, I mentioned that some serious scientists think global warming is a hoax. That remains the case. They may be wrong of course. But that was not the main point of my post and I don’t think I have ever said that I think it’s a hoax. If you can find something along those lines please post a link so we can all verify your claim.

I am not anti-science. I am anti-scientism. In complex systems, it is easy to overstate scientific certainty.

Jason Scheppers
Dec 28 2013 at 8:21pm

Dr. Roberts:

I am not so sure your comments are very civilized on this podcast. I don’t see much listening going on or acknowledgement of the portion of the opposing view. I fully admit that I may not do much better, but here is a new track.

Dr. Curry lamented about academics venturing into policy. She thought that in many cases, the policy work was assigned to less skilled scientists or at least those less skilled were developing the policy. I agree that in many cases that might be what is happening, but ivory tower or not, translating academic mumbo-jumbo into actionable policies, has to be one of the key reasons why public funding of research should be done.

I do not dispute that there is a lot of marketing and horse trading that goes into making policy, but that does not make it less important. It is sad when solid research is ignored or discounted because skewed political process does not want to listen. It however is important that practical application of good research get implemented. I don’t discount the miriad of terrible unpractical application that are labelled as practical, but that does not change the reason for the research.

We have quite poor tools to arrive scientifically at what a concensus is. I am not aware of a good scientific method that combines the disparate means and methods used in developing a body of liturature, and how to weigh the evidence.

It seems to me that the market test, is the best method to see what academic research is valuable, but many would not like that and the associated selling and lobbying associated with the market evaluation. But the invisible hand of what individuals are willing to invest in is probably better than any mathmatical reviewing methods of the data.

On a separate subject. Nit picking. Dr. Curry indicated that when ice melted in the ocean it was like ice cubes melting in a cup of soda. She indicated that the fluid level would rise. I would disagree. The mass displacement for a 1kg ice cube is the same as the mass displacement of 1 kg of liquid water. It is only the melting of ice on top of land that modifies the water level.

It is nit picking elements like these that make me worry that the whole complex modeling is likely significantly flawed. There on millions of little assumptions baked into the models and so many chances to get it irrelevant.

Eric Tergerson
Dec 28 2013 at 11:26pm

I highly enjoy and value the podcast, it is a much-needed antidote to the far left ideology I am used to here on the left coast, (and Portland, Oregon to boot), and which I have been guilty of as well.

You interview a truly wide variety of people, on different sides of the political spectrum, with widely varied areas of expertise. I never really know what’s coming at me when I hit ‘play’ on the phone.

We all have biases of course, and Halvard showed his by mischaracterizing you and your stances with terms like “anti-science” and claiming your stance is a simple as believing its a “big hoax”

Those are simplistic arguments against your position, just as the simplistic arguments *against* climate change from the religious or paranoid right claim there is a liberal conspiracy, or that God wouldn’t allow it, or will save us all (I don’t talk to my crazy uncle enough now-a-days to be up to speed on that one)

I appreciate your nuanced take on the issue.

However. (you probably knew there was a however..)

I stand with:
Geoff Harris
Victor Venema
Nathan Beckmann
Greg McIsacc

All of whom made very good points.

I don’t think you or Judith Curry are climate deniers, and Judith seems to be coming at her data and opinions with sincerity and knowledge in her field. But there were some very troubling arguments throughout the interview, many of which were addressed by the above commenters.

I think there is controversy where policy decisions are involved, but not in the data about climate change. There is *great* distortion of this data, but, uh, I’m gonna have to go with the IPCC as the best source for this information.
I can’t touch on everything, but the reference to global temps since 1998 really is a red-herring, one that that is pointed out in this graph: http://www.csicop.org/uploads/images/si/morrison-global-warming-3.png
[source: http://www.csicop.org/si/show/has_global_warming_stopped%5D

With this said, keep up the good work, and the comments I’ve seen here are much higher quality than other places on the interwebs!

Dan Pangburn
Dec 29 2013 at 1:03pm

“…natural internal variability and also solar variability in terms of explaining the past climate variability and also projecting into the future.” explains average global temperature measurements since they have been accurately measured world wide (before 1900) at http://agwunveiled.blogspot.com/

Dec 29 2013 at 2:02pm

It seems from some of the comments that since Russ Roberts did not actively oppose what Judith Curry was saying, he must be anti-science or a denier (or some such).

What is interesting is that no one (NO ONE) has yet to explain why the “CO2 is THE factor” model cannot explain the “pause” in the rise in global temperatures.

And no one has yet explained why the CRU thought it necessary to “hide the decline” …

Climate Science ceased to be a science years ago when it was hijacked by political activists. It is indeed a loss because we have stopped trying to understand the forces of nature that cause changes to our climate and change – the only factor the activists accept is the increase in CO2 because of us, humans.

As Russ Roberts indicated – asking for an explanation of the “pause” seems tantamount to being a heretic.

Dec 29 2013 at 3:48pm

The default hypothesis ought to be that it’s a random process.

Even the cycles aren’t real but an artifact of their representation.

Just as cycles in a continuous fourier analysis depend on the interval you want to represent the behavior over.

By themselves they have very noisy coefficients, with a Rayleigh distribution. Choose a different time interval length and you get a different coefficient for the same cycle.

Their variance is given by a power spectrum which may be smooth, but the actual cycles have a highly random coefficients.

As such there are rises and pauses and falls that don’t have “explanations” at all, unless you can untangle what the speaker talked about and worse, since all those input cycles are themselves random processes with their own random cycle coefficients.

In the absence of a simple and proven theory, there’s nothing to explain. The stuff just happens. A random process will do it all and more.

It’s like reading chicken entrails, if you try.

My sociological instincts say that if you pay for reading chicken entrails, an industry will spring up on it. That explains a lot, and leaves the climate alone.

Eric Tergerson
Dec 30 2013 at 7:03am


you typed many sentences… yet- I’m still in the dark.
please elucidate?

*edit* im detecting a touch of the gish gallop.

you are not short on the words.

An argument from ignorance (the variables are too complex to model) [throws papers in the air] is not a valid argument. Show your work, please.

Bill Gardner
Dec 30 2013 at 7:04am

I appreciate Dr. Curry’s argument that this is a wicked problem.

At the beginning of the interview, however, she says that current accumulated greenhouse emissions will cause slow warming over a 50 year period. She clearly refers to a long term trend, because she stresses the importance of decadal variation that has yet to be understood. I assume that she would agree that continued greenhouse emissions will cause additional long term warming over and above that currently built into the system.

This is an argument for a long term strategy of planetary conversion to non-fossil energy production, no? She’s absolutely right that there is no obvious, simple, or immediate solution. But that doesn’t mean that we do not need a solution.

Dec 30 2013 at 10:05am

@Eric Tergerson

The data, like encryption, is scrambled enough so that you can’t get information about causes out of it.

The law of large numbers has wiped out its causal content.

If I generate a thousand numbers and tell you the sum; then replace half the numbers and tell you the new sum; and so forth, there isn’t enough information in the sums for you to tell what I did.

You can tell though that the sums are normally distributed and have certain simple autocorrelations.

But a million processes you can construct give you those same statistics. Mine gives you no better fit than any other.

Random processes are very general. You can’t invert them to get causes unless you want to check for a cause you have in mind.

So talk even of trends or cycles isn’t getting to causes, it’s just remarking on the data.

On the theoretical side, we know that you can’t do it. Even the equations we know are beyond solution.

What’s driving it is money and grants, not scientific curiosity.

You can’t be scientifically curious about the climate cycles because there’s no next step you can take, beyond, like Kepler, just writing them down.

I always use curiosity as the test for science. Global warming seems to be pretty short on it.

Curiosity welcomes the other side.

Jeremy Weltman
Dec 30 2013 at 10:18am

[Comment removed pending confirmation of email address and for irrelevance. Email the webmaster@econlib.org to request restoring your comment privileges. A valid email address is required to post comments on EconLog and EconTalk.–Econlib Ed.]

Dec 30 2013 at 11:24am

You mentioned that some serious scientists think global warming is a hoax. And then you said.
How seriously can you take the scientific consensus when you know that a lot of the experts are on the government and foundation funding gravy train and their livelihood depends on remaining on the right side?

So you did not use the word hoax. I am sorry, I guess I totally misunderstood where you stand regarding all these scientists.

Just a follow up. Does the Hoover Institution get money from the fossil fuel industry?

Dan Pangburn
Dec 30 2013 at 12:19pm

Curiosity resulted in the discovery of the two primary drivers of average global temperature that explain the reported measurements with 90% accuracy. http://agwunveiled.blogspot.com/. CO2 is not one of them.

Common motivation can result in activity very similar to conspiracy.

Dec 30 2013 at 12:36pm

First off, I think so much of the debate on the exactness of the climate models can be considered moot, especially, given that as Dr. Curry stated:

there are lots of reasons beyond greenhouse warming to transition to cleaner energy…. It’s a huge health issue in Asia, in China, in Bangladesh, in India. It’s just a huge issue in terms of air quality…. Not only are they poisoning the air but also even the water and the soils. Their soils are losing productivity because of all the pollution. So, if you have another reason for moving to clean, green energy besides just the greenhouse warming issue, then I think you have… a winning solution. So, trying to bring in other aspects–whether it’s economics or environmental quality, public health, national security… then it doesn’t seem like such a potential risk

With respect to the actual scientific debate – I appreciate the skeptics and their curiosity and desire to make sure we are reacting to the right thing. I also appreciate the genuine curiosity and dedication of those who are convinced by what data is available so far. (I really appreciated the link from Eric Tergerson)

Finally, I think that saying we don’t have all the data and understanding to qualitatively say that there appears to be a strong correlation and likely scientific causation between human activity and global climate is a bit like saying that physics was incomplete in 1687. Sure, Newton’s laws of motion were incomplete representations of actual motion, as refined later by Einstein, but for most practical cases, they are very useful. Here, dealing with climate, we are essentially measuring Einstein’s particles and trying to extrapolate to Newton’s broad formula. Sure, we may not have every kink worked out to understand quantum theory (equivalent to weather), but I think the data are strong enough to say F = ma in the broader sense, and that’s something we can start to work with.

If not, there’s always the previous argument from Dr. Curry.

Dec 30 2013 at 1:17pm


There are too many degrees of freedom in the models and too many in the data.

The law of large numbers takes over and throws a cloak over it all.

If somebody, like Kepler, discovered that climate periods were proportional to the three halves power of their amplitude, you’d have an analogy and some underlying theoretical symmetry to look for.

Dave Nickum
Dec 30 2013 at 3:31pm

Let us assume that climate models are of little value and climate change is a wicked problem. What still worries me is if you look at the number of disasters (flood, windstorm, epidemic, drought, extreme temperature, slide wildfire, wave/surge, etc) that have occurred since 1900, the trend is worrisome (only estimates until the 1970s). A chart looks like a hockey stick, jumping upward in the 1970s, this is where the number of disasters starts to take off like a rocket. Even though global warning is not being taken seriously by many, these increases in natural disasters are being taken very seriously by insurance companies.

Also assuming we can’t predict or understand the climate, how about this fun points –

1. Research on air quality in New York, Phoenix and Baltimore shows that ambient Co2 parts per million (ppm) levels can spike into the 400s, 500s and 600s, which climate modelers predict will become the norm in 20 to 30 years. Right now the global average is 393 ppm.

2. A 2009 study done by European scientists looked at hospital admission data from 12 major cities including Dublin, London, Barcelona, Athens and Rome from at least a three-year period. They found that for every 1-degree Celsius temperature increase, hospitalizations from respirator and asthma related illnesses rose by 4.5 percent.

3. Shells of many organisms in the sea are short of aragonite, a form of calcium carbonate that gives them strength, but whose formation acid discourages. Weaker shells means fewer shelled organisms and less food for fish. Note – harvest buckets can only be filled half full now because any more weight will crush the shell fish on the bottom.

4. Our ocean saltwater makes up 87.5% of our planets water and it provides 50% of our oxygen. Humans are slowly turning it into a desert – over fishing, acidification and heating.

So let us do no harm as our response to all the harm we are currently doing.

Daniel Barkalow
Dec 30 2013 at 6:16pm

I just looked at what I think is the EPA graph you were referring to (http://www.epa.gov/climatechange/images/indicator_downloads/temperature-download2-2013.png), and, aside from being a terrible graph (uses less than half of the vertical space, puts the axis through the middle for no good reason, overlays a bar graph with a line graph), it really looks like 1998 is a huge outlier in a 40-year period with a consistent trend, rather than the boundary between two 20-year periods with different trends. Given the data up to 1997, the simple model (linear, plus a bunch of random noise) does a good job of predicting 1999-2012, despite not predicting 1998.

Upon further consideration, I wonder if the disconnect is between people who expect systems to have Brownian noise and people who expect them to have white noise. (That is, are there randomly distributed changes to the value overlaid on a trend, or randomly distributed offsets to the value.) In some systems, a large random change in a variable leads to the future values being significantly affected, while in others, a large random change in a variable doesn’t substantially affect the future values.

So I think most climate scientists see 1998 and say, “Randomly, that year all the energy was in the lower troposphere, rather than distributed among other places. But what matters isn’t the lower troposphere, it’s the whole system, and that’s just an outlier.” On the other hand, people who are used to variables with tight internal feedback say, “It was at a high level, if only for a moment. Why did it then fall dramatically and not reach that peak again over the next decade?” Of course, in economics, every indicator you report has tight internal feedback because people react to what you report. But the climate doesn’t react to our measurements, so we shouldn’t expect, when, one year, we see a lot of energy in the parts of cycles where we can measure it, that it will be in those parts in subsequent years.

Of course, using a line graph is a great way to make people think that adjacent values are directly related to each other, which is another problem with the graph. If the graph just had dots at the data points, it would be much more natural to ask “Why is 1998 out of place?” rather than “Why is 1999-2012 below 1998?”

Russ Roberts
Dec 30 2013 at 11:39pm


Again, I encourage readers to go back and read my original post from 2007 cited above.

You ask about funding for the Hoover Institution where I work. Most of the Hoover Institution’s funding as far as I know comes from individuals. I don’t know if any comes from oil companies. What I do know is that George Shultz, perhaps the most illustrious and respected fellow at Hoover–Reagan’s former Secretary of State, drives an electric car, supports a carbon tax and thinks the science behind climate change is straightforward. Evidently, he didn’t get the memo.

People who believe climate change needs to be dealt with seem eager to believe that those who are skeptical must be being paid to be skeptical. I don’t think that’s true. I think many first-rate scientists (Freeman Dyson for example) have not been convinced of the science. Maybe they will be eventually. Maybe someone will develop a sufficiently through model of climate that even skeptics will have to accept it. Climate change advocates seem to think we’re there now. Maybe we are. I don’t think so.

Dec 31 2013 at 3:32am

I have to say I was a bit disappointed with this podcast. I was trained as a scientist (in the biological sciences) and understand that our models of many complex issues are works in progress (and may always be!). But does that mean we should just sit on our hands and shrug off these issues? Nonsense!

We still don’t understand even a fraction of how our brains work but would we tell patients undergoing major surgery to not take a general anesthetic because we don’t understand how they work? Seems like a similar argument is being made here.

And the whole biofuel thing seems like a red herring argument to me. Even assuming that whole issue wasn’t bent to serve the corn lobby, any “guess and test” solutions we try will have their share of failures. Doesn’t mean we should stop trying.

Dec 31 2013 at 3:20pm

It seems to me that the claims we should keep trying or we have to something are only true if what we are trying has a minimum cost. I will pay $20 a month for a 10 year term $100,000 life insurance policy even though I will probably never receive anything for the money because the cost is low compared to the potential benefit. I will not pay $500 per month. My risk of dying hasn’t changed, but the cost of doing something “just in case” is now too high.

Eric Tergerson
Dec 31 2013 at 10:09pm


“The data, like encryption, is scrambled enough so that you can’t get information about causes out of it.”
That applies to complex systems, chaotic ones, like the weather, when you try to reach out too far out into the future, by extrapolating from a model. However, in the short term, i.e. up to a week, weather models are quite successful.

Climate models, while complex as well, look at much larger arcs of time. They don’t try to model granular events, but systemic changes. The cause and effect of CO2 is old-school at this point, the greenhouse effect as a theory is pretty solid- we’re not talking someone’s masters thesis.

“What’s driving it is money and grants, not scientific curiosity.”

I think that’s a bit denigrating to scientists in general.
Besides, how else is science done? Charity? U.S. taxpayer funded grants fund some of it (much to the chagrin of some) and private grants and funding covers the rest I guess. The debate is pretty reasonable in here, so fortunately there is a relative lack of accusations of “shills” doing the research. Good science doesn’t care about the funding, and more about the rigor of the results, including prior plausibility and if other studies jive with it independently. Funding can sometimes be a clue, but in full-time skeptical circles this reeks of the “argument ad Monsantum”(pertaining to the debate around GMO’s)i.e. “Because the research came from Monsanto, it must be false”
Clear logical fallacy. When it comes to climate science, I’m sorry that people on both sides of the debate fall for it.

I think what I’m trying to contribute here, is the following:
Climate science *is* complex, more-so than Al Gore’s movie or many on the left would make it out to be. Concessions must be made on our confidence levels of the details of precise temp. rises, sea level rises, catastrophic results, and other details.
However, the fact that our current, and rising levels of CO2 emissions *will* result in an overall rise in global temperatures, is science. And good science at that. This overall rise in the global temp. average will translate into changes in regional and local climates, the specifics of which, are not clearly understood.
-And I have to take *their* word for it. The specifics beyond that? Up for debate.

Shawn Barnhart
Jan 1 2014 at 7:57am

What bothers me about the climate debate is that the conclusions about what the climate is or isn’t doing and what should or shouldn’t be done about it seem to align pretty well with the general economic morality of the people involved.

People who believe in climate change also seem to have general anti-materialism economic philosophies, the greater the latter, the greater their belief in the former and the more they advocate for more interventionist policies.

Those in opposition seem to follow a similar pattern, although more muted and less strident, and curiously there seem to be few that advocate for reducing laws and regulations on emissions.

Given the complexity of the science (“a wicked problem”), it’s difficult not to see a lot of confirmation bias on both sides of the aisle, perhaps more so on the side advocating the climate change argument.

It’d probably be impossible to get data, but it would be interesting to see an statistical analysis of the political and economic beliefs of those involved on this debate to see how well they correlate with the strength of their advocacy for either side of the debate.

Jan 1 2014 at 8:05am

@Eric Tergerson

Climate models, while complex as well, look at much larger arcs of time. They don’t try to model granular events, but systemic changes. The cause and effect of CO2 is old-school at this point, the greenhouse effect as a theory is pretty solid- we’re not talking someone’s masters thesis.

Short term weather forecasts work by the weather over short times being two-dimensional – in two dimensions, flows go to longer rather than shorter scales. Vorticity is conserved rather than kinking in a third dimension and breaking up. A few layers of the third dimension are put in in hopes of extending the forecast but it breaks down quickly. Those would be the granular events that it “doesn’t try” to model. Breaks down, would be a better description.

To get a climate response, though, you can’t average the equation and solve that instead. You need an ensemble average, that is, a bunch of solutions to the real equation, which solutions you then average.

Think of it as the difference between taking a deep breath and jumping into the water, and jumping into the water and taking a deep breath.

You need the climate response to CO2, not some energy model.

Analogy: suppose a large ball rolls into a small ball. You might suppose from energy conservation that the large ball stops, and the small ball rolls off very fast with the energy of the large ball.

That’s energy conservation. But it’s not right. Energy is conserved in a different way. You have to do the equation instead of invoking the single principle to get the answer.

Likewise the climate.

It reacts and apparently opposes the change.

To show that that does not happen, you’d have to do not radiation balance but figure out what it in fact does with those equations that we can’t solve.

Besides, how else is science done? Charity?

Science works by curiosity.

Lots of people don’t have the bug and may be competent in some corner of science, but they go home on weekends and holidays and don’t think about science.

The ones with the bug are working every day because it’s also a hobby, the curious ones.

You can’t bribe the curious ones. They go with the hobby, not the career.

The others go with the career.

The difference between being a saint and a shill isn’t so much character as interest. That feeds back on character.

The curious ones don’t know what CO2 does; the career minded ones do. In error.

George P. Burdell
Jan 2 2014 at 2:32pm

Professor Roberts,

I love your podcasts, but I must point out one small error. Judith Curry is at “The Georgia Institute of Technology” and not “Georgia Tech University.”

Other than that, this was a great listen. Dr. Curry has engaged with bloggers like Anthony Watts (Watts Up With That on the web) and has been blasted for giving credence to any skeptics (not deniers). I would think scientists would welcome an open review of their data.

I also like how she characterized “climate model taxonomy” as a distraction from some of the -potential- core scientific work.

– GP Burdell

Mr. Econotarian
Jan 2 2014 at 2:42pm

I find an interesting parallel between minimum wage and anthropogenic greenhouse warning. Basic theory suggests that minimum wages affect labor demand and that greenhouse gasses help to trap heat in the atmosphere. But actual data from the complex economy or environment sometimes is not always clear. In part, this is due to the small incremental forcing effect from slowly increasing CO2 or fairly small minimum wage increases. Also the forcing may cause unexpected things to happen, such as more clouds or fewer worker benefits.

Geoff Harris
Jan 2 2014 at 2:47pm

Curry’s “engagement” with Watts and the associated lies, distortions, conspiracy theories and general nastiness on his site explain partly why serious scientists seem to have little respect for her.

Jan 3 2014 at 12:45am

[Comment removed for supplying false email address. Email the webmaster@econlib.org to request restoring your comment privileges. A valid email address is required to post comments on EconLog and EconTalk.–Econlib Ed.]

Jan 5 2014 at 11:42am

Thanks, once again, for a wonderful show. It is beyond me how anyone as thoughtful and in-depth as Judith Curry can have such harsh critics. It only confirms my view that the Global Warming topic is not science, rather politics in the form of a religion. I think science, even areas with lots of common ground, is never unanimous. There is always push and pull on new information. The total compulsion for lock step agreement tells me plenty. And I’m not a denier or conspiracy theorist — simply a seeker of knowledge.

Geoff Harris
Jan 6 2014 at 11:52am

[Comments removed for making ad hominem remarks. –Econlib Ed.]

Jan 7 2014 at 9:58pm


This is actually a really good time to discuss economists and pundits view on science. Why? Because parts of the US are experiencing some colder weather than usual. And of course we hear the claim that global warming is not real or as Steve Forbes said it: Global warming is simply socialism in drag(I think he is in the conspiracy camp).

The term “global warming” has the word global in it. And if I am not wrong most students learn in junior high (at least in the country I am from) that weather and climate is not the same. So if you know that, you would never jump to the conclusion that a little bit of cold weather disprove the scientific theory of global warming.

So I am not sure why educated people are making that jump. Either they went to a school with questionable science teaching, they did not pay attention, or they let their political agenda trump logic and science.

It has been warmer than usual so far this winter in part of Europe, and of course people living there cannot say that the warm local weather prove global warming.

So take a look around you these days and listen what the free market people are talking about. This weather is actually a good test of science understanding.

I know a thin person and he lives in Texas, but I do not think all people in Texas are thin….

Geoff Harris
Jan 8 2014 at 11:05pm

I listened to the interview again and thought I’d summarize some of my objections to it (although there are so many things of note that I am probably missing many).

– Curry answers the question about imposing a carbon tax by suggesting, so it seems, that a tax is not a solution because the effects of CO2 take such a long time to manifest themselves. And yet though not taxing carbon will ensure that the effects will be greater that gets no mention.

– Curry creates and then attacks a straw-man with her false assertion that people see CO2 as some sort of fine control knob. No they don’t, they see it as a greenhouse gas that has very well defined physical properties.

– Russ brings up his own straw-man by complaining that he thinks science is not done by consensus. Nobody suggests it is. But policy decisions, where affected by science, are indeed normally based upon scientific consensus.

– Curry says that climate models “all have a sensitivity to carbon dioxide”. This implies that sensitivity is built in to the model when in fact it is an emergent property of each model.

– Curry brings up the old chestnut of temperatures being flat since 1998. Russ has said he is most interested in data, not models etc, data. Let me ask you Russ. If you have an economic data set where an anomaly occurs one year (a natural disaster for example that wipes out crops or causes a spike in some resource price), would you then consider it appropriate to reference statistics for subsequent years to that anomalous year? Because that is what Curry is doing by referencing temperatures to 1998, when there was a huge spike in global recorded temperature due to an El Niño event. If you believe in data you should recognize when it is being misrepresented.

– Russ describes the EPA as “so-called unbiased, so-called objective measure of the climate”. The insinuation there is that EPA is in fact biased. Do you have any evidence to suggest that its climate data is biased or not objective?

– Then it is back to referencing the data from the late 90’s – are you really surprised that Sachs gets “mad at you”. You are supposed to be data focused – see above.

– Curry builds another straw-man by suggesting that by focusing on CO2 we miss opportunities to deal with other problems. Why? Can we deal with only one problem at a time suddenly?

– Curry creates yet another straw-man suggesting that we are “blaming everything on greenhouse gases and thinking that by reducing emissions of greenhouse gases we are going to solve all our problems”. Nobody is doing that. I have never heard anyone suggest that reducing emissions of carbon dioxide will do anything to alleviate Atlanta’s expected doubling in population or the “tri-state water wars” (her examples of problems we are missing).

– Curry discusses the difficulties of measuring glacial mass balance and of attributing falls to climate change. Oh it is so difficult! Yet we have good measurements of mass change in Greenland and Antarctica, we know that most glaciers are melting (Glacier National Park is soon to be No-glaciers National Park). Talk about manufacturing doubt!

– Russ says, “Do you want to say something about the polar bears?” Where did that come from? Was this scripted, prearranged or what? I don’t believe Curry knows the first thing about Polar Bears or their status. And a reference to Happy Feet? What do you know about Polar Bears to be so flippant?

– Then we get to “doing no harm”, with the implication that doing something about carbon emissions would do harm. No evidence was offered or asked for beyond bio-fuels and nobody except the farm lobby and their defenders supports the current US position on producing ethanol from corn. Where is the evidence that putting a tax on carbon emissions would do “harm”? What “unintended consequences” might there be from taxing carbon?

– Then it is on to assertions that renewables are too expensive while ignoring the real costs of fossil fuels. At least Curry did indicate that particulates have health effects but that doesn’t seem to get through as a cost (one of many) to be placed against them in the balance with renewables.

– Curry spends a lot of time criticizing models, that they “can’t really say anything on time scales of 50 years” and that analyzing their output is not fundamental useful. Yet if we are making irreversible changes to the climate of 50 years hence, isn’t that something we should be concerned about and which should guide policy?

– Russ says, “I understand the incentives that people face in how to think about what to work on and what side they come down on, what evidence to consider”. The insinuation is that scientists chose which side to “come down on” because of the “incentives”, that they reject evidence if it doesn’t match the apparent “incentives”. Can you name a climate scientist who has considered the evidence for and against climate change but has decided to “come down on” the conventional side because the “incentives” were better? Can you name anyone who has selected which evidence to consider on the basis of the “incentives”? In short do you have one iota of evidence for that statement?

– Russ says that the fact that Pat Michaels makes money from selling skepticism doesn’t mean he is wrong. No of course not. But you were keen to point out what you saw as the “incentives” for scientists to behave immorally earlier and yet you emphasize the opposite here.

I’ve never had the feeling from previous podcasts that Russ and a guest have prearranged or scripted things that they wanted to get across, but that Polar Bear section was so gratuitous that I now wonder. How much of the discussion was planned in some respect?

Russ Roberts
Jan 9 2014 at 10:58am

Geoff Harris,

We get your point. I did a bad job interviewing Judith Curry.

Interestingly, in your catalog of my interviewing sins you neglected to mention the times I challenged Curry. And if you missed it, you might enjoy the EconTalk episode with Robert Pindyck. He supports a carbon tax. I tried to treat him (and Judith Curry) as I do all of the guests on the program–challenging him in ways that let listeners learn. Your tone and style are part of what makes the public conversation so difficult. There appears to be a certainty that I don’t understand given the imperfection of the past models models to predict the current data. Just as in macroeconomics, this should lead to a sobering humility rather than hubris and outrage. Your assumptions about my motives and attitudes do not help.

Alas, this interview was not pre-scripted. Your sinister thoughts about polar bears are unfounded. The threat of climate change to polar bears is a common theme among activists. I was simply curious as to whether Curry had a view on the evidence.

You persist in asking about the effects of a carbon tax. A carbon tax would artificially raise the cost of energy. This may or may not be a good idea. But paying more for something than you have to, is costly. It may be a cost worth paying, but it’s a cost. The magnitude of the costs and the benefits are what are unclear.

Geoff Harris
Jan 9 2014 at 8:46pm

[Comment removed for multiple policy violations. See your email to discuss editing the comment to be in accord with our comment policies.–Econlib Ed.]

Geoff Harris
Jan 10 2014 at 9:33am

Russ, thanks for replying to my comments.

I was disturbed that Curry, and to some extent you, discussed the subject by attacking a series of straw-men. In other words instead of discussing the subject as it is understood by others she created her own versions of the issues that were easier to attack. This is not how I expect a scientist to behave.

Although you criticize climate models, they have successfully forecast a variety of changes. However, their purpose is not directly to ‘predict’ current temperatures. The IPCC models use historic data up until 2005 and project from then. The historic data include El Niño/La Niña, volcanic eruptions, solar intensity and so on. After 2005 these are guessed according to historic averages. If these events do not follow historic averages, the short term projections will be wrong. That is assured, whether the models are good or bad. This characteristic of the models is well known to climate scientists. It does not in itself invalidate longer term projections – time will tell how accurate they are.

As for your discussion of Polar Bears, when an interviewer asks me a question on a subject that is not vaguely within my expertise, I always make it clear that I am not qualified to give an informed answer.

Regarding a carbon tax, yes of course it makes things more costly. All taxes do. The question for economists and policymakers is how to extract the necessary revenue at the least “cost”. It is not clear to me that a system based upon taxing labor and company profits is necessarily better than one based upon taxing resource use, pollution and so on. That would be an interesting debate to hear.

LD Bottorff
Jan 11 2014 at 1:25pm

I can’t believe that she said it, but it is in the transcripts;
“once you melt the great glaciers, it’s like adding more ice cubes into your glass of water, once they melt it causes the level of water in your glass to rise.”

Adding more ice to your glass of water, or the ocean will cause the level to rise. Once the ice is in the glass or ocean, melting the ice will not affect the water level.

David Zetland
Jan 11 2014 at 4:17pm

Russ — you really did drop the ball on economics here. Yes, the climate models are inaccurate in terms of decimal points, but VERY FEW scientists would say that CO2e emissions are good for climate. Most will say they are bad. The details will emerge, but the main problem — disruption — will happen. That fact (some call it an opinion) makes action against CC a good idea. A carbon tax makes a lot of sense (as do other taxes on pollution), but a REAL no brainer is a reduction in subsidies for fossil fuels (and biofuels, which were subsidized by the same old crowd that subsidizes any sort of ag). The IMF has blasted them as wasteful and anti-poor (http://www.economist.com/news/finance-and-economics/21593484-economic-case-scrapping-fossil-fuel-subsidies-getting-stronger-fuelling)

I’m glad that Curry is methodical but that doesn’t mean that we can’t take no regrets actions now (as is the case with actions to improve water management, drought or not).

Jim Feehely
Jan 14 2014 at 7:27pm

Hi Russ,

I enjoyed your chat between fellow skeptics.

However, I have become weary with these banal arguments about causation that any thinking person knows cannot be resolved. That the ‘climate debate’ has been dominated by a general objective to ‘prove’ causation is the real problem. That is a result of the right re-charcterising that debate as being about ‘climate change’ rather than about ‘global warming’, one of the great propaganda successes of our time.

Fact – we know that high levels of carbon in the atmosphere is bad. The current scientific consensus seems to be that concentrations about 450ppm is very dangerous. In 2013 we passed 400ppm.

Fact – concentrations above 450ppm will cause uncontrollable warming.

Yet we continue to twitter on about whether humans are causing ‘climate change’ and what that change may look like.

We do not need to agonise about causation. We know enough about the effects of carbon in the atmosphere to know that human contribution to carbon concentration must be reversed. But, because of the debilitating obscurity about ‘climate change’ causality, we instead are more concerned with preserving our ‘standard of living’ without any regard to quality of life now, or in the future.

It is obvious to me that under your ‘first do no harm’ mantra, we have an obligation to stop harming the atmosphere. But you have applied that mantra only to the economy.

‘Doing no harm’ to our economic circumstances is guaranteeing the destruction of our environment. Our economies are built on the myth that economic growth is limitless, apparently the only phenonemon in our little world that is limitless. Under current circumstances, endless growth means endlessly rising consumption and endless rising consequences of consumption including endlessly rising pollution and environmental degradation. If we are to pursue endless growth, we must find a basis for that aspiration that is not based on consumption.

That is what we should be debating – what does prosperity and the good life look like in an economy that is not obsessed with growth in consumption? Instead, we debate whether our fatal obsession with growth is causing ‘climate change’ because we cannot accept that endless consumption growth must be slowed and ultimately reversed. And the likes of Judith Curry and you argue we should do nothing until that causation can be proved or disproved. That debate is banal and hopeless.

I really do despair for future generations

Russ Roberts
Jan 14 2014 at 9:49pm

Jim Feehely,

I do not associate the use of the term “climate change” with the right.

If causation can’t be established, we are not doing science but religion. When you write things like:

Fact – we know that high levels of carbon in the atmosphere is bad. The current scientific consensus seems to be that concentrations about 450ppm is very dangerous. In 2013 we passed 400ppm.

Fact – concentrations above 450ppm will cause uncontrollable warming.

you damage your case. Those are not facts. They are hypotheses.

I would expect the billions of people who are desperately poor to care about economic growth. I care about growth on their behalf. Even if you are right about carbon, doing something about it that keeps those billions protected is not so easy.

Jan 15 2014 at 2:01pm

Like a lot of people, I stopped listening when she said 1998. If she’s going to make assertions like that without trying to justify her unusual interpretation, I can’t trust anything else she says.

Russ Roberts
Jan 15 2014 at 10:09pm


Sorry you stopped listening.

Are you saying that there has been warming since 1998 and she is just wrong about the data? My look at the data is the same–there is no warming since then. That doesn’t prove anything in and of itself–maybe other factors have outweighed the effect of increase carbon. But are you saying there has been warming?

Otherwise, I don’t understand why 1998 is such a red flag for you.

Jan 16 2014 at 3:22pm

Quite honestly, I couldn’t finish this podcast. I tried – very hard. I’ve studied fluid mechanics in graduate school but I’m no expert on climate issues. I’m taking no sides on this issue. And I understand all forecast models at the end of the day have to deal with separating noise from signal.

Judith Curry was obvious be evasive by comparing climate change to water problems in Atlanta in terms of their priorities. These two are apples and oranges. Climate change, if indeed man-made, is global, requiring coordination of many nations; water problem is local, in this case restricted to Atlanta. How can one compare their priorities? This is just ridiculous. Should we solve the hunger and malaria problems in Africa before dealing with water shortage Atlanta? Examples like this really make me wonder whether she’s drawing conclusions based on evidence or simply her own opinion.

Towards later part of the interview, Judith Curry sounded like a faithful religious zealot claiming there has been no solid evidence that God does not exist.

Geoff Harris
Jan 16 2014 at 7:53pm


I tried to explain the effect of mentioning 1998 on an audience familiar with the debate, but maybe I was unclear. Ask yourself this: is it reasonable to draw a conclusion about a dataset if the removal of one data point from the set would change that conclusion? By making claims of no warming since 1998, you and Curry are effectively saying that you can draw a line from 1998 to any subsequent point and the line will be either flat or downward sloping. But 1998 was an exceptional El Niño year. If the 1998 data is replaced with the average data for the surrounding years, your claim becomes invalid. Knowing this, would using 1998 as a reference point in similar circumstances be acceptable practice in economics? I think that your the answer to this question would be highly pertinent.

Global temperatures clearly vary year by year but there is thought to be an underlying trend upwards. Foster and Rahmstorf, 2011 [1] show a very clear trend by removing the effects on temperature of various natural but unpredictable events (El Niño, the level of solar irradiation, volcanoes). There is no pause in the underlying trend after 1998.

You may also be interested in a recent study by Cowtan and Way, 2103 [2], that investigate the effects of coverage bias on the HadCRUT4 temperature index. HadCRUT4 is a widely used index that appears as you say to show 1998 as the warmest year. However, little data is available for the Arctic. Omitting Arctic data causes a bias in the index because the Arctic is the most rapidly changing part of the globe. Cowtan and Way used various interpolation methods to estimate missing Arctic data and remove some of this bias. The resulting charts show that there has indeed been significant warming since 1998.

[1] http://iopscience.iop.org/1748-9326/6/4/044022
[2] http://onlinelibrary.wiley.com/doi/10.1002/qj.2297/abstract

Todd Weber
Jan 16 2014 at 8:23pm

Thank you for this excellent discussion. Very informative.

Russ Roberts
Jan 17 2014 at 3:04pm

Geoff Harris (and Ryan),

Removing one data point would be silly and meaningless. It’s not about drawing a line from a single year like 1998 to the present using 1998 as a starting point in order to suggest that the climate is cooling. That would be poor science. That isn’t what Curry has done.

Read this post by Curry. Look at the data presented. There appears to be a slowdown or pause in warming starting around 1998. It is not based on 1998 which is clearly an unusually warm year. It is based on the last 15 years or so which show a pause or hiatus or plateau. A 15-year phase is not decisive. It’s just provocative. Obviously it could be that other factors have offset AGW to lead to that phase. But there is nothing dishonest or suspect abut noting that the data of the last 15 years seem different.

I know there have been pauses in the past. This pause may be followed by an acceleration in warming. So again, a pause doesn’t disprove AGW. It just should make you think whether the models have captured everything in the complex system of our climate. And claims that there has been a pause don’t prove that someone is a cherry-picker or dishonest.

Jan 17 2014 at 7:04pm

Burton G. Malkiel’s _A Random Walk Down Wall Street_ , still in print!, has a nice graph of coin tosses which is regularly identified as a classic buy signal or a classic sell signal.

Random processes do those things.

It’s chicken entrail reading unless you have data that’s not short compared to the cycle you need to exclude.

A trend is a indistinguisable from a long cycle.

You can’t tell whether the earth is warming or cooling. “Underlying” can’t be determined.

To get out of the situation you’d have to identify the cause of every fluctuation so that there’s no more randomness in the problem, which we can’t do.

So it comes down to what hysteria you want to fantasize about. None is the best idea, hitting all sorts of various optimal criteria.

Thomas Webler
Jan 18 2014 at 2:30pm

I listened because I thought I should, although it was painful and irritating. The woman paints herself as reasonable and non-biased, but there was bias in everything she said.

I am SO very tired of the claim that solar causes more CO2 than gas because of the need to cycle gas plants. NREL has studied this. They found the increase in CO2 emissions from more cycling is 0.2% of the emissions that are saved by replacing gas with solar. So instead of reducing CO2 by 100 units we only reduce it by 99.8 units because of cycling losses.

Curry has that, and many other points, terribly wrong. But Russ clearly enjoyed their philosophical common ground, possibly explains why he failed to challenge her on key claims.

Jan 19 2014 at 5:18am

It looks like a lot of people are confusing sea ice melt with land ice melt. They are then using this confusion to attack a specific comment by Curry.

I thought it was fantastic to hear a scientist admit that so many things are still unknown and that more time and focus should be spent on those unknowns. The AMO and PDO obviously need considerable research, especially since the AMO is due to switch in the next 5 years. In the past, this correlated to a cooling of the northern hemisphere.

Something to take from this is that the science can’t be settled when there are so many unknowns. Saying it is settled is basically saying you know all the drivers. Along with positive and negative feedbacks. The performance of the models shows that to be nonsense.

Let the research continue and if we can clean up our energy use in an affordable way in the mean time, let’s do it.

Jan 19 2014 at 7:37am

Dear Russ

I have a master in climate science and an Phd in economics. I was always fascinated why communication between these two disciplines seems to be so complicated. And this podcast it yet another example.

Generally, I like your podcast a lot, as you try to get to the depth of a problem and try to be as unbiased as possible, given your neoliberal background. I used to consider myself rather left-wing, also because I listen to many episodes of your podcast, I realized that good ideas and concepts come from all sides.

Coming back to this episode, this is a exception to your normally high standards. I understand that bashing climate models seems to fit your general suspicion about modeling and prediction of “decimal points”. But there is a clear difference between climate models and economic models in this respect.

Climate models are based on physical laws that are proven to be true, moist importantly that CO2 captures heat. Thus, we know that CO2 IS a control knob for long-term climate change and claming the opposite is defying principle physics. Sure there are many feedback loops in the climate system we cannot accurately model and that is why there is still a large uncertainty associated with the warming for a given amount of carbon emitted in the long run (there is no such clear connection in the short run due to climate variability. Reason? see: http://www.youtube.com/watch?v=e0vj-0imOLw&feature=youtu.be). Given this uncertainty society has to decide how to handle that, but it cannot be an excuse for inaction, per se.

Economic models are not based on some fundamental laws, but mostly on the disputable notion of homo economicus in some form or the other. This is needed to allow a mathematical treatment of economics. Yet, lacking a indisputable unpinning economic models can — and should – be challenged on various grounds.

This does not mean, however, that such a skeptical approach is equally meaningful for climate models and no serious climate scientist would go back to the basics of physics and start a branch such as “behavioral physics”. So it makes sense to be critical to all kind of model output, but such criticism should be done based on a profound knowledge of the specific model and not based on false reasoning by analogy.

Two last point:

When it comes to the incentives of the scientist to do certain work and getting quoted, I claim that Curry`s quotations, interviews and so on would have be much less, if she had stays on the “consensus” side of climate scientists.

On the climate physics: Russ, you should invite also a mainstream climate scientist. Given the many comments, e.g. about the nature of the hiatus, your listeners would deserve it. How about Reto Knutti, a lead other of the long-term climate change part of the newest IPCC report.



Ron Crossland
Jan 19 2014 at 2:59pm

Russ – your intentions to educate are much appreciated. As a relative newcomer to your podcast (last 12 months) I’ve learned a great deal and enjoy how you work at managing bias.

This episode did cause me to look further into your guest’s science claims, as I found the discussion problematic for several of the reasons already stated.

I’m better educated but uninspired by Curry and a little disappointed in you for choosing her to discuss this difficult subject. The economics extend beyond a carbon tax discussion.

But rating you a bit lower on this podcast doesn’t make a trend. I’ll be back with an eager mind to listen to future interviews.

Jan 19 2014 at 5:00pm

It used to be that physics discussions included physics.

That was before climate science.

Although actually there were publications near the field that were good.

One guy, in the 70s, thought that long wavelength ocean waves come from maser-like action, namely that shorter waves (which grow faster in wind) preferentially break at the crests of longer waves, imparting their energy to the longer waves.

That accounted for the too-quick growth of long waves in wind.

Everybody thought, that’s interesting.

Nobody questioned his credentials.

He wasn’t asking for political power and money. He was just curious and stumbled on this idea, which, as far as I know, is correct.

Jan 19 2014 at 5:09pm

“Climate models are based on physical laws that are proven to be true,…”

Climate models skip other laws that are known to be true (Navier Stokes equations for starters).

The result is something dreamed up.

I don’t know where this style of physics argument came from. It wouldn’t have worked when I was doing physics.

Climate scientists do not know what they claim to know. That’s my argument, reasons above.

Geoff Harris
Jan 20 2014 at 11:11am

rhhardin, climate science covers a wide variety of fields and it is true that some (or even many) of these do not involve physics. But physics is nevertheless central to climate science and to modeling climate. Curry is herself a physicist, after all.

You have suggested that a trend cannot be distinguished from a cycle, but the distinction here is that we have known changes in forcing caused by CO2. If the rise in temperatures was just part of a cycle, what happened to the effects of the extra forcings (which have an expected effect that matches the observed rise)? And if your point were to be accepted then we can never in our lifetimes determine the existence of a trend in temperature. In 50 years, having continued to emit CO2 at accelerating rates and with temperatures much higher, we could still claim that we see no trend, that it could just be a cycle. In other words that argument leads to permanent inaction.

As far as models using approximations rather than Navier Stokes equations and others, you might be right that this invalidates the results. Alternatively, the approximations might well be sufficiently good representations of the physics to give good results. Can you prove the argument one way or the other? From what I have read, models have indeed been successful at projecting various climate changes, which indicates to me that the approximations are functional, even if not perfect.

Jan 20 2014 at 12:17pm

And if your point were to be accepted then we can never in our lifetimes determine the existence of a trend in temperature.

Exactly. It’s not my choice, it’s mathematics. The eigenvalues blow up in the distinguishing matrix. You can work it out yourself, or any engineering graduate student can do it for you.

That’s how I know that climate scientists don’t know what they claim to know, on the data side.

There’s an exception. This “uncertainty principle” of data not being short compared to the cycle to be excluded is a small signal result. If you have a large signal to be detected, then you can beat the eigenvalues on their own ground just by exceeding them.

In beamforming that’s called supergaining. There’s some really neat mathmatics there but it takes a large signal, which we do not have here.

The point of the hockey stick was to be just such a large signal, so that it beat the uncertainty principle. An explosion can’t be a cycle.

Alas the hockey stick was just amateurish data reduction (with all the signatures of an amateur result, too), so that’s not around anymore.

So the result is that we can’t tell. There are lots of things we can’t tell. The climate scientists ought to be saying we can’t tell, not that we know. Then you’d have a philosophical policy debate which is where it belongs, without the posturing.

going backwards,

You have suggested that a trend cannot be distinguished from a cycle, but the distinction here is that we have known changes in forcing caused by CO2. If the rise in temperatures was just part of a cycle, what happened to the effects of the extra forcings (which have an expected effect that matches the observed rise)?

Matching a random process isn’t hard. Did I talk about this already?

It has to do with building models with approximations, and what will always happen.

There’s something called Kalman filtering, which wiki explains more obscurely that it ought to.

It amounts to least squares, but is factored out so that with each new data point, it tells you how to change your model, taking into account the new data point and all of the old and the performance of your model under all changes.

Now what happens when your model, not being able to solve the Navier Stokes equation, wants a fake term that is usually called, say, “effective viscosity” in its substitute equation. What value do you use? Who knows? Kalman filtering will tell you how to adjust it though so as to match the new data as well as possible, as well as all of adjusting your other fake parameters covering other things you’re not doing exactly.

They don’t use Kalman filtering, but do in effect.

That makes your model into a curve fitting exercise, not physics.

So of course you match the forcing term.

I don’t know, maybe this is partly a call for climate scientist self-awareness as much as a call for science to be brought back.

There must be a thousand points that need attention more than just my two (no theory, no data).

Thanks for the cordial reply.

Jonathan Fraser
Jan 20 2014 at 12:41pm

It’s fascinating to see how our views on climate change have become part of our societal identities.

We attach so much importance to the issue that our positions have become indelibly engrained. Climate change is politicised to the point that both sides are convinced that the other is either incredibly naive or woefully corrupt.

Similar Earth-science issues (like plate tectonics) never created such a controversy outside of academia. But with climate change the finger of blame is pointed at each and everyone of us, so it is perhaps unsurprising that the argument has split down political lines: the left see the right as ostriches burying their heads in the sand, whereas the right see the left as cunning politicos trying to push their social agenda.

There is no point refuting any of the skeptical arguments stated here as I am not an expert on client science (and you shouldn’t trust a single expert anyway). But it is a fact that the scientific consensus states that climate change is happening. Ignoring this implies a fundamental mistrust of the scientific method; a philosophical approach which, although messy, has proven itself robust and effective for nearly 300 years.

The argument therefore should not be about whether climate change is happening; it should be about what we want to do about it. Whereas the former should not be a political issue, the latter is. More time should be spent debating approaches that reflect different political viewpoints. If both sides appreciate that bigger government is not the default answer, then perhaps the debate can move forwards.

Russ Roberts
Jan 20 2014 at 4:46pm

Jonathan Fraser,

You write:

But it is a fact that the scientific consensus states that climate change is happening. Ignoring this implies a fundamental mistrust of the scientific method; a philosophical approach which, although messy, has proven itself robust and effective for nearly 300 years.

I don’t think so. The scientific method isn’t about trusting scientists. It’s about experiments that isolate causal effects that make precise predictions and that can be replicated.

Climate models appear to me to be like models in epidemiology and social science. They use statistical techniques to simulate experimental methods. The application of such techniques to epidemiology and the social sciences has not proved to be reliable. Instead, the results of such efforts often fail replication tests.

That doesn’t mean that we have learned nothing about economics or psychology or nutrition or what causes cancer. Or why the earth is getting warmer. What it does mean is that those who use such techniques should be cautious and humble. I don’t see a lot of that in the climate discussion. That makes me suspicious. Maybe it shouldn’t. Maybe the statistical models that underlie climate analysis and predictions are unlike those in macroeconomics, epidemiology, and nutrition. Happy to understand why.

This has nothing to do with whether there is science underlying some of our understanding of the processes or whether this about natural phenomena rather than people. It’s about the nature of the methods use to measure and assess causation. There is a lot of science that we understand about cells and metabolism and diet. But there is a lot we don’t understand about the effect of say, alcohol on life expectancy.

Jacob A. Geller
Jan 21 2014 at 11:21am

Russ, I consider myself a critic of Sachs on a number of issues, but I think you’ve treated him unfairly here, and failed an Ideological Turing Test.

Here is where I think you’re being unfair to Jeff:

I mentioned it to Jeffrey Sachs in a recent episode of this program and he laughed at me and sneered and said–I can’t remember what he said; I didn’t look that up; but he thought that was an incorrect way to think about things. I’ve been on the web because I’ve found this so fascinating and you hear things like, ‘Well, but the last decade is the warmest decade in recorded history.’ I think, well, but it’s not supposed to be flat; it’s supposed to be rising because of CO2 was the cause. And in general, the whole attitude, to even suggest that there has been a stagnation in global temperature change is considered–I don’t know–heretical. People get really mad. They don’t go, ‘Well, it’s really complicated,’ in the nice tone of voice you just used. They get mad at you. Do they get mad at you?

I was surprised when I heard you say this, because I remember that podcast and I don’t recall Jeff laughing, or sneering, or getting mad, but I do remember him rebutting the point with simple logic and data. I thought, “OK, Russ is obviously not recalling this conversation correctly,” then I considered that maybe I am the one who is misremembering the conversation, so I went back and listened to it. And the simplest way I can put it is to say that basically my recollection was correct, and yours was wrong and unfair.

Here is the conversation:

Russ: I’m not a deep student of climate change, but I have noticed that there is murmuring that the last 10 or 15 years have not shown much global warming. And this seems surprising in light of the incredible amount of carbon dioxide being pumped out of China, and elsewhere, as the world has gotten more developed.

Jeff: I think that’s not a right observation, Russ.

Russ: Which part?

Jeff: The fact that the last 10 years have not been consistent with the modeling and with the expectations of climate change. There’s a lot of silliness in that oft-repeated observation. The last decade has been the warmest decade in instrument history. What is true is that 1998 was exceptionally warm because it was a very strong El Niño year. So a lot of people that play up this–mainly for propaganda reasons, in my view–say, well look, 1998 was the peak and then if you draw the line from 1998, you just don’t see all that much. But what we do see is that if you strip away these seasonal and inter-annual phenomena of the El Niño Southern Oscillation (ENSO) cycle, if you take into account the decadal ocean temperature trends and so forth, what we face right now is very, very clear. And that is a greenhouse gas-driven warming of the planet that is both highly significant, very dangerous, continuing at a rapid rate; and the best of our ability, scientific inference, very frightening to the future, with a lot of instability likely to arise.

Jeff certainly did not laugh, that’s for sure. I don’t think he “sneered,” either. He did say that what you’d read on the internet was “silliness,” and said it was “propaganda,” but if you buy his explanation that in fact the temperature changes in the last ten years are consistent with climate modelling and that people do often use the year 1998 as their baseline in order to make the last 15 years look “flat,” then it’s not unreasonable to call it silly propaganda. And even if you disagree with me here, if you go back and listen to the podcast (I can’t do it justice in writing) his tone of voice is sufficiently calm, and his explanation sufficiently technical and precise and deep (and accurate, as far as I know) — very much like Judith Curry’s, in fact — that I just don’t think it’s fair to say that he “sneered” at you, even if he used the terms that he did.

And while he obviously was frustrated, I don’t think it’s fair to say that he was “mad” or “angry” at your point, or that he considered your point “heretical.” He didn’t get mad, and he took it seriously enough to break it down in a fairly dry, boring, technical tone of voice. And you both kind of left this conversation pretty much where it was at that point, but if you’d continued then I have no doubt, on the basis of how the conversation was going at that point, that he would have continued to dive deeper into the data and the theory and the evidence over the last 10-15 years.

Note by the way that everything I’m saying is completely invariant with respect to whether or not Sachs was correct. He could have been completely wrong, yet he would nonetheless have been wrong in a civil and respectful way — not an angry, sneering, laughing, intolerant sort of way.

Most importantly, not only did you misremember the tone and emotional resonance of his response to your point, you forgot what his response even was. It’s one thing to disagree with his interpretation of the data, but it’s another thing to forget what his interpretation was entirely, and as you know very well it’s not possible to disagree with his interpretation of your point if you don’t even remember what it was. You basically just ignored or forgot what he told you, and chalked it up to basically emotional response to a reasonable point, but what I think you’ve done here is exactly what you’re accusing Sachs of doing — you’ve ignored his point, and responded emotionally.

Russ, this is unlike you. You tend to be pretty good at Ideological Turing Tests, at understanding and re-stating forcefully the points of your intellectual opponents. But you failed here, and I hope to see better in future.

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0:33Intro. [Recording date: December 17, 2013.] Russ: We're going to talk about climate change, what we know and what we don't know. But before we do, I want to talk about why I invited you to the program. A listener recommended you, so I checked out your web page and I found something very surprising. There wasn't any yelling there--at least apparent yelling. There were thoughtful comments by you and your readers. And I read your rules for posting comments; they are a fantastic guide to civility. They seem to be working, and I was struck by how rare that environment is, especially in the area of climate change, which is so contentious. So, in the spirit of civility, which I like to think is the spirit of this program, let's talk about climate change. In 2010 you testified before Congress and called climate change a 'wicked problem.' What does that mean? Guest: Well, basically it means that it's even hard to constrain it in terms of the dimensions. The more you consider the problem, the more dimensions and complexity the whole issue seems to have. And this is true not just of the physical and chemical and biological system that comprises the earth's system and contributes to its climate, but also the social and economic dimensions that seem to feed back onto the physical climate system through our use of burning of fossil fuels, the decisions we make. All of this is connected in a very complex way. And another characteristic of the 'wicked problem' is that there's no simple solution. And that every solution you propose seems to have unfortunate unintended consequences. So, climate change to me seems to me to be the archetypal wicked problem. Russ: So, a lot of economists say it's an easy problem to solve: all we need to do is put on a carbon tax. We may struggle to figure out what the right amount is. But that seems like a fairly narrow solution. It will have some consequences that are negative. There may be some unintended ones. But what's your take on that approach of, 'Well, we just need to reduce the amount of CO2 (carbon dioxide), and we know how to do that; we'll make it more expensive artificially through a tax. Guest: Well, two things. Even if we were successful at reducing the concentration of CO2 in the atmosphere to the desired levels, we might not see any impact on the climate for 50 years or more. Further, the issue of extreme weather events such as more hurricanes, more floods, more droughts, whatever, it remains unclear as to what extent those are actually becoming worse in any way that we can attribute to greenhouse gases. So even if we are successful at reducing CO2 emissions, exactly what impact this is going to have on our climate on time scales over the next 50 years is probably not very much. Russ: Why is that? Why would it take 50 years? Let's say we did a fairly--I should tell you, Judy, that my background is I'm an economist, which I think you know. And I'm a very, very casual consumer of the literature in this area. I'm a skeptic about our ability to model complex processes. So I come to the data and the models with some skepticism to start with. I'm skeptical of centralized solution. So you are going to educate me today; and I assume I have some listeners who are in the same boat as I am. But why would it take 50 years? If we are going to reduce the amount of CO2 won't that slow things down and bring them to a halt or even reverse them fairly quickly. Guest: Well, CO2: some people talk as if CO2 is a control knob, you know, of the climate. But that control knob really works on time scales more like centuries to millennia. Because of the way the earth's system metabolizes, stores, and releases carbon into the atmosphere. The ocean stores a lot of heat. And it takes, in terms of the turnover time of the ocean it takes a while of heating to be realized in the atmosphere. So there's a lag in the system associated with the way the oceans store heat and the way carbon is stored in the atmosphere and the way carbon is stored in the oceans and the land vegetation. So there's a lot of long-term feedbacks in the system that don't really allow changes in carbon dioxide to fine-tune your weather or your climate. So, there's a lot of natural variability that contributes to climate variability and change related to the sun, volcanoes, and the ocean circulation system. So all of these things are going on, on top of greenhouse warming. And greenhouse warming actually projects onto these other modes of variability. So the whole system is very complex--wicked, if you will. Based on our understanding there's really no way to fine-tune the weather and climate by changing carbon dioxide concentrations.
7:41Russ: Well, it's funny you say that. Because the thing that comes to my mind as an economist is the way some macroeconomists talk about stimulus spending or government spending: we just need to--or of the money supply depending on what flavor of economist you are--we just need to tweak this variable; we have a control knob, they tell us; we've just been ignoring it or we haven't been tweaking it the right way or turning the knob the right way. And what you are suggesting is that there is something similar in climate. In the case of economics, when I say things like that, a lot of economists say, 'Oh, you just don't understand. It's not your field. There's all these studies that show that government spending stimulates the economy, and when we're in the doldrums like this, we just need to increase government spending.' And I say, 'Well, what about this event? What about that event? What about the models that don't predict so accurately?' And I assume in your field, there are people who act like there's a knob. Are they wrong? Or am I wrong about that analogy? Guest: Okay. Well, actually, it's a slow control knob. It's more the advocacy groups and Al Gore, you know, will talk about it as if there's some sort of fast control knob. But I think that people in the IPCC (Intergovernmental Panel on Climate Change ) and the climate scientists don't regard it as a fast control knob. And in fact you might have heard that the carbon dioxide that we've already admitted--there is warming in the pipeline for the next 50 years even if we stopped emitting carbon dioxide. So if you've heard 'warming is already in the pipeline' that's another way of reflecting that it's not a fast control knob. That we're stuck with what we already have in terms of atmospheric CO2, and that's going to be contributing to a warming effect for the next 50 years or so, even if we were to immediately, drastically, reduce CO2 emissions. Russ: Do we know how big that warming effect would be if we did level things off? Let's just say we could hold the amount of CO2 emitted by human beings constant. Do we have a prediction for what would happen 50 years from now? I'm sure we do. I'm sure we have many. And I'm sure they have decimal points, like they do in economics. My question is: How accurate do you think those predictions are, and what kind of consensus? Even though I don't think science is done via consensus. Is there any consensus at all over the predictability of that change? Meaning, let's lock things in like they are now; 50 years from now what will we get? Guest: Okay. The climate models are narrowing in, and they all have a sensitivity to carbon dioxide. But how much the climate would warm if you doubled, and whatever. And the climate models generally give you, in the first half of the 21st [changed from '20th century--Econlib Ed.] century, it would be about 2-3 degrees Centigrade per decade [?century?] of warming that we should expect from the climate models. And the fact that we really haven't had any warming since 1998--the global temperatures have been essentially flat for that period--tells us that the climate models aren't accounting for certain things. There are a number of explanations for why we haven't warmed for the past 16, 17 years now. And people usually talk about, well, it's unpredictable variability. Well, okay; a lot of climate variability is unpredictable. And mostly when they say 'unpredictable climate variability,' this refers to the natural internal oscillations of the ocean atmosphere system. Well, what does that mean? You've heard of El Niño and La Niña. Those are relatively short-term natural internal oscillations. And on longer, decadal time scales, there are things like the North Atlantic Oscillation and the Pacific Decadal Oscillation that are long-term, multi-decadal--variability on time scales of 60-70 years--that have a very large impact on the climate. And what we've been seeing over the last period that we haven't had any cooling is a shift to the cool phase of the Pacific Decadal Oscillation. And this is largely regarded to be a major contributor to why we haven't had any warming. Now the climate models don't do a good job at all with, say, the multi-decadal variability. So, the climate models really haven't predicted something like this to happen in the presence of ever-increasing carbon dioxide. And then we're in a cooling phase for the sun. This is working out to be the coolest sun that we've seen in 100 years. And this is contributing to the warming. And this is something that the climate models can't predict. So, these climate models are very good at predicting one little piece of it--what the increasing carbon dioxide will do. But the problem is all other things aren't equal. We have the sun doing something unusual, we have the Pacific decadal-- Russ: Just like economics. Guest: Yeah. Right. If you are looking at just one piece of it and trying to make it a simple problem, then they have a solution: of this 0.2 degrees Centigrade per decade of warming. But the climate system is much more complex, with natural internal variability, particularly these multi-decadal oscillations in the ocean, solar variability, volcanoes are always a wild card. And things like changes in air pollution, changes in the regulatory environment like continued decreasing of the chlorofluorocarbons to help with the ozone problem. All of these things also change the composition of the atmosphere in ways that are influencing the climate. So all of this adds up to no warming for almost 17 years now. And climate scientists are still debating and trying to figure out what's going on. We have some subjective explanations and possibilities for what's going on, but something quantitative or having the models actually be able to predict something like this--well, no, we're not there yet.
15:29Russ: I'm glad you brought that up. Because I was going to bring it up. As a data person, interested in how people build hypotheses around data, when I went to the EPA (Environmental Protection Agency) site before our conversation just so I'd get a so-called unbiased, so-called objective measure of the climate; and you look at the data and, as you say, the late 1990s to today, it's flat. There's ups, there's downs, but it's basically flat. If you are looking at any other data besides climate data you'd say, whatever was causing--there are two possibilities. Either we don't fully understand the mechanisms, which is almost always the case to some degree. Or, possibly, the forcing variable, carbon dioxide in this case, hasn't been increasing--I went to another site and found that that's not the case. Or maybe there is something else that has changed that, as you say, is causing cooling that, in the absence of that, there would be warming; so because of that factor we can't see the warming in the data. And that's of course possible. Hard to know for sure but it's always possible. But when you mention that flat temperature reading over the last 15 years or so, people get really mad at you. I mentioned it to Jeffrey Sachs in a recent episode of this program and he laughed at me and sneered and said--I can't remember what he said; I didn't look that up; but he thought that was an incorrect way to think about things. I've been on the web because I've found this so fascinating and you hear things like, 'Well, but the last decade is the warmest decade in recorded history.' I think, well, but it's not supposed to be flat; it's supposed to be rising because of CO2 was the cause. And in general, the whole attitude, to even suggest that there has been a stagnation in global temperature change is considered--I don't know--heretical. People get really mad. They don't go, 'Well, it's really complicated,' in the nice tone of voice you just used. They get mad at you. Do they get mad at you? Guest: Oh, yeah. Russ: What do they say? And what do you say back? Guest: Oh, well, I don't say anything back, actually. I just let them say what they want. There are several blogs--well, one blog that's just devoted to trashing me; and several other blogs where it's a major part of their discourse, trying to take every statement I make, place it in a different context, and say very negative things about me. There's a number of people who don't like what I'm saying. But what I'm trying--the thing that I've been saying for the past four years now is that we've oversimplified the climate problem. By thinking everything is caused by CO2, we're missing a big part of the story. And this hiatus in warming, these flat temperatures since 1998 and even earlier, tells me that we have to pay a lot more attention to this natural internal variability and also solar variability in terms of explaining the past climate variability and also projecting into the future. And that's been my main message, and as a result of saying this I show up on various people's lists of climate deniers and things like that. And so my message, I think, is the appropriate one scientifically; and people who are making policy decisions need to have this more nuanced understanding. Because if they are wanting to do something to help reduce our vulnerability to climate variability and change on time scales of a few decades. By focusing on this very long-term issue of carbon dioxide they are going to miss opportunities to deal with problems like reducing our vulnerability to hurricane landfalls or to addressing issues of potential water shortages. By only focusing on the greenhouse warming aspect part of the problem, we are missing opportunities to really reduce our vulnerability to these kind of issues which have the largest economic impact associated with climate variability and change. So that's been my message, and it's not a popular one because it goes contrary to the IPCC consensus. And any climate scientist who criticizes the IPCC or its consensus is automatically branded as a heretic. And I don't think that's a healthy situation either for the science or for the environment for making policy decisions. Russ: So, I'm going to read something. I was going to read it later but I'll read it now. I personally find the term 'denier' repugnant for a whole bunch of reasons. But I'm going to read this quote. This is from the Society of Environment Journalists, which is a guild of sorts. It's a club of journalists who write about the environment. And someone there wrote, on their website I think,
Judith Curry's blog, Climate Etc., is an exception to the stereotype of denier blogs. Curry is a real climate scientist with strong credentials. Committed to reason, evidence, and open inquiry, she is willing to examine legitimate points the climate skeptics may be making--as well as the evidence and arguments from mainstream climate science.
I don't know what the opposite of damning with faint praise is, but that's it. That's a pretty good way to be described, it seems to me, as someone who writes about this topic. Guest: Well, yeah; I could almost put that in my mission statement for the blog. It describes perfectly what I'm trying to do. But the irony of that is that they accept, without question, that my blog is a denier blog. So that really points out, sort of, in my opinion, the stupidity of applying the word 'denier' to somebody who is trying to open the dialog, to discuss climate science and the policy implications beyond the narrow framework of the IPCC. Russ: Well, keep it up, is all I'll say.
22:19Russ: Let's talk about the water shortage issue you mentioned a minute ago. What is the issue there? Guest: We've had droughts, in the United States and globally; every recorded history, pre-recorded history is documented by tree rings. Droughts are nothing unusual. However, as population increases and energy systems rely on water availability for cooling, etc., our vulnerability is increasing. So our vulnerability to diminished water resources is one of the key concerns about climate variability and change. But I should add that overall increasing carbon dioxide is expected to increase precipitation globally--although there are places where this might decrease. It's not uniform globally, but overall you expect more rainfall. But that doesn't stop people from inferring that global warming is going to cause more drought. Even the IPCC doesn't find huge evidence in most regions for any increase in droughts. And even if you do find an increase in droughts in a certain region, it's very difficult to attribute that to greenhouse warming. These multidecadal ocean oscillations like the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation are very powerful controls on the decadal variability of droughts. And this really swamps anything that we can identify as a drought that we can identify that might have been caused by global warming or by greenhouse gases. The other issue is that in many cases--I'll speak to the Southeast United States, which is my home territory. You think of the Southeast United States as a place with plenty of water. But actually in Atlanta and Alabama and Florida, the river basins that feed the fresh water actually have a small catchment and are very susceptible to drought. And so the region is very concerned about any possible change associated with greenhouse warming. And the models, the climate models, are very ambiguous about whether it's going to increase by 20%, decrease by 20%. And the regional planners are very worried. And when I met with them, I think it was in 2011, to discuss this issue, I said, 'Why are you worried about plus or minus 20% when the population of metro Atlanta is scheduled to double on a time scale of 30-40 years?' We're talking about 100% change, as opposed to this plus-or-minus 20% that they're worried about. And also they are big-- Russ: Meaning there's bigger things you've got to be worrying about than that. Guest: There's bigger things to worry about than climate change. There's also the tri-state water wars about how to share water between Alabama, Georgia, and northern Florida; and that has the potential to change the water availability far more than anything related to climate change. So in a lot of these issues, when we think about our vulnerability to climate change, our vulnerability to climate change is really only a small piece of what should concern us. And people have an outsized worry about it relative to other things that they should be worrying about. So blaming everything on greenhouse gases and thinking that by reducing emissions of greenhouse gases we are going to solve all our problems, that to me is a naive fantasy, in terms of not really understanding the full nature of our problems. And also it's naive about thinking we have this fine control knob on our climate with CO2, which we don't. Russ: Should we worry about sea level? Is that a legitimate worry, do you think? Rising tide? Guest: It is. Sea level is probably the one global issue that you can attribute to an extent to greenhouse gases. But sea levels have been rising for several centuries. People talk about coming out of the Little Ice Age, and that's sort of a nebulous term, but sea levels have been rising for several centuries. And the big question is whether there is any acceleration that you can identify from greenhouse gases. And that's something that's hotly debated. In terms of looking at local sea-level rise, say, if you are looking at the New Jersey/New York area, which is highlighted as a result of Hurricane Sandy, well there are some natural land subsidence; and then there's also subsidence associated with land use. As we build heavy buildings, as we withdraw the groundwater, there's a human-induced sinking. So a lot of the local sea level rise can often be attributed to either natural subsidence or to human land use. And in many places this far overwhelms any sea level rise we are seeing associated with greenhouse warming. The whole sea-level rise issue is quite complicated. You have to untangle the local natural and human land-use contributions. And then you also have to, when you are looking at global sea-level rise issues, you have to understand how much of this is sort of natural, associated with natural internal variability and this long-term coming out of the Little Ice Age versus something that is being accelerated by greenhouse gases. It's hard to untangle it. But looking forward, if you are overall warming the climate, you have a thermal expansion effect in the ocean, where it makes it expand; and so sea level rises, and that's not too much. Again, the bigger wildcard is how much the glaciers are going to melt. So, once you melt the great glaciers, it's like adding more ice cubes into your glass of water, once they melt it causes the level of water in your glass to rise. And so that's the wildcard. Russ: If it gets warmer, they are going to melt, right? Guest: Yeah, they are going to melt. But it's not that simple. Often as it gets warmer there is more snowfall in the high latitudes, so you can be accumulating glacier mass. So, trying to look at the mass balance of the glaciers--accumulation, melting, and then calving, where pieces actually break off--is a complex problem. And it's really only for the last decade or so that we've had really good satellite observations that help us keep track of the mass balance. But even then it's not simple to interpret these satellite observations and to infer glacier-mass balance. And so, like in Greenland, where we are actually having some accumulation, a lot of snowfall in the Northern part, it seems like there is melting in the Southern part; and on the Southeastern part there is a lot of calving of glaciers. And trying to understand how this all adds up to--is it losing mass? Well on Greenland it does seem to be losing mass. But to what extent is this natural variability, associated with the ocean oscillations or greenhouse warming? Again, sorting all that out, you know, is still fairly ambiguous. So, how to attribute this to greenhouse warming is very tricky. There is a still a lot of uncertainty in how to attribute all of this, and how to--even if we can identify, okay, the glaciers are losing mass, to what extent is this simple warming from carbon dioxide or related to these natural internal variability? So there's no simple interpretations to all this that are unambiguous in terms of what carbon dioxide is doing. We have a sense that in general this would be melting, warming. So there would be melting glaciers; that would contribute to sea-level rise. But there is also increases that are potentially associated with greater snowfall. And how to sort out that out remains rather unclear. And there are differing interpretations in the scientific literature. So that's a sign that this is still a relatively--it's not a very mature field in terms of our understanding.
33:02Russ: I'm going to ask you a more general question, but before I do, I want to stick with ice for a minute. Do you want to say something about the polar bears? Guest: Okay. The polar bears have been an icon for global warming. And in some regions the populations are increasing. In other regions, they seem to be decreasing. There is a hot debate amongst biologists as to exactly what's going on: what's the populations and then how to attribute any changes in the populations, to global warming. So I think a lot of people have dropped the polar bears as an icon for global warming because it doesn't really seem that the populations are shrinking at all, or at least in any way that can be attributed to global warming. I think you are seeing a lot of people drop the polar bear icon for global warming. Because that doesn't seem to be holding up. Russ: I think it's Happy Feet, is the movie where the polar bears are having a tough time. Maybe they'll issue a sequel.
34:16Russ: I want to ask a general question, because again, a lot of what you are saying reminds me of the way I feel about macroeconomics. So, when I think about macro-economics, I want to like to call a 'late Hayekian'--the early work of F. A. Hayek, who was trying to create a general, global, micro-based model of business cycles and how the economy varied. And he gave up on that for a whole bunch of reasons, one of which is just that it was too hard. And in his later years--certainly in his Nobel Prize acceptance speech. He's much more agnostic--'skeptical' would be a better word--about our ability to model the macro economy in any precise way. We understand general trends, certain forces that are at work. But to suggest that we can steer it or manipulate it is a fantasy. And when I say things like that, people say--or when I say things very similar to what you just said--I want to say the economy is complex, we don't understand all the causal forces, we can't control it--they say, 'Well, that's just an excuse. You don't want to do anything. You are just saying that it's all complicated.' I'm going to throw that back at you. I have my own response on the economics, which is my own response, which is: First, do no harm. And I see a lot of evidence that when we think we can control things and we can't, we actually do a lot of harm. But in the climate area, a lot of people say, 'It's better safe than sorry.' So, okay, we're not sure; you say we're not sure about the sea level, what causes it. We're not sure if Greenland and glaciers are melting or not shrinking; there's snowfall. The polar bears are shrinking and expanding in some places. We're not sure of the role of volcanoes and the sun and the ocean effects. But isn't it better safe than sorry? Wouldn't it be better to--okay, so it's not a tight knob, it's not a great control knob, carbon dioxide. But since we know it has some effect, uncertain perhaps in terms of the magnitudes, wouldn't it be better just to, as an application of precaution, let's dial it down? Better safe than sorry. And this is, by the way, the position that Robert Pindyck, the economist on this program earlier this year. He said, 'Yeah, we don't know; there's a lot of uncertainty; the models are mediocre. But better safe than sorry. We know it's some effect, and so we may not know the perfect way to cope with it, but we know we should do something. What's your reaction to that? Guest: I guess I'm in the same camp as you: First, do no harm. And I think the push to biofuels is an example where we thought we could do something that was relatively quick and easy and there seemed to be a lot of unintended adverse consequences. Soils, food prices. And it seems that overall it's not even reducing greenhouse gas emissions. The net change on all this might not be anything. So that's an example of doing something that you thought would help, that actually has harmed. If you step back for a minute about the precaution of reducing greenhouse gas emissions, as a precaution: well, if clean, green energy is the same price as dirty energy, I think people would naturally prefer to use the cleaner source of energy. I mean, that's just--I think people prefer clean energy. But they don't want to sacrifice the abundance or the ready availability of the energy; and they don't want to pay too much more for it. So, until we figure out how to make sure the clean energy would be abundant and cost competitive, I think it's going to be a very tough sell. Are we going to sacrifice the availability--especially in the developing world? There is a very different problem in the United States. They don't have enough power as it is, and part of their--a key element--of their development goals is more abundant power. And there's no obvious way to provide all that they need with purely green energy. Although some countries like India are making really good progress in terms of implementing solar power and things like that, it's just a very tough thing to do. So we have to look at the unintended consequences. When you are implying the precautionary principle, it's a mistake just to look at one piece of it and not consider the unintended consequences. Again, that's one of the hallmarks of the wicked problem framing, is that no matter what you propose to do, there are unintended consequences and you have to ask, is the cure worse than the disease? Even with--until we get better battery storage for wind and solar, it's not clear that those power sources are actually--at least, say, in the United States--helping us reduce CO2. Because when the wind dies out you have to quick crank up the gas burners. And the spin-up for that--using as much fossil fuels as you might have been saving from when you did the wind energy. So, you know, what the actual savings are isn't always obvious. And what the unintended consequences are need to be looked at. So, again, the key issue is if we can figure out technologies and infrastructures to make clean energy available at approximately the same costs as fossil fuels, then we are ready to make the transition. But until then, it's hard to justify this on a very massive scale. Various regions, experiments--some things will work and some things won't. I think it's very interesting what California is trying to do, etc. Again, that's a very wealthy state. They can afford to experiment in ways that Africa may not want to experiment, because they are desperate for energy and coal is the cheapest and most obvious way to provide them with that energy. So, how do make those calls? When you balance all the various issues? Again, I'm just waffling and saying, you know, complex problem, uncertainty, whatever. But at the end of the day I think we are transitioning to cleaner energy, and there are lots of reasons beyond greenhouse warming to transition to cleaner energy. Especially coal burning and the small particulate issue. That's a major health issue. It's a huge health issue in Asia, in China, in Bangladesh, in India. It's just a huge issue in terms of air quality. It's a massive health issue. So I think they are motivated to try to get away from coal burning as a public health issue. Not only are they poisoning the air but also even the water and the soils. Their soils are losing productivity because of all the pollution. So, if you have another reason for moving to clean, green energy besides just the greenhouse warming issue, then I think you have, I think, a winning solution. So, trying to bring in other aspects--whether it's economics or environmental quality, public health, national security. If those issues are also drivers for going to clean energy, then it doesn't seem like such a potential risk, just going to clean energy over the global warming issue. That's my take on how to think about the problem. And again, it's mushy but I think it's consistent with global warming and energy issues as being wicked problems.
43:17Russ: So, you've been--I want to wander to a broader topic; we'll get back to some climate issues in a minute. You've been out of graduate school for about 25 years or so. That's how long I've been out. When you come out of graduate school, I think inevitably you have some romance about the enterprise you are involved in. There are many, many nonmonetary aspects of being an academic that are inspiring and exciting. But I wonder how you feel about how your particular field has changed as you've grown up in it and been out for 25 years. Do you think that the academic world as it's currently constituted, the returns to publishing and the way that academics are successful--are they conducive to truth-seeking? Do you feel that we are making progress in the scientific world on this particular topic? Or are we in trouble? Guest: I think we're in big trouble. When I left graduate school, nobody called themselves a climate scientist. They were an atmospheric dynamicist or a geochemist or a physical oceanographer or things like that. And we were all focused on increasing fundamental understanding. And that was the focus. It was the breakthrough in understanding, changing the way people think, was what mattered. And somebody who published too many papers was probably looked at with suspicion--they are doing the quick and easy stuff; they are not really digging in. It was potentially superficial. The other thing that was looked down upon, say in the 1980s, was doing something that was too applied, working to deal with regional problems or something like that. That was viewed as soft core; it was what the people did who couldn't really make fundamental contributions to understanding, so they moved on to some of these applied topics, which were useful in some way to regional decision-makers. I would say in 2000--it was a gradual transition, but I think circa 2000 there was a switch to people finding it beneficial to self-label them as a climate scientist. There was a lot of money, research dollars in this area; there was a lot of influence to be had, in terms of sitting on panels and boards and committees and being interviewed by journalists and being invited to testify in front of Congress. And so the value and the influence of the scientist sort of switched into that dimension where your measure of influence was not so much how you increased our fundamental understanding of how the oceans worked, but it was really to what boards and committees you sat on, your press, and your influence in policy, being invited to testify in front of Congress, and whatever. So I've seen that switch. The problem is, the concern that I have for the health of our field, is that there's still a lot of fundamental things that we don't understand. The climate models aren't good enough. We need to go back to basics, increase our understanding about the non-linear dynamics of all these ocean oscillations and complexity of the system and things like that. There are a lot of fundamental things that are getting short shrift, that the sex appeal in our field right now and a lot of funding is to do what I call mock[?] 'climate model taxonomy', where people are analyzing the output of climate models and finding something interesting, alarming, or using them to infer that we won't be able to grow grapes in California in 2100 or something like this. This is the stuff that gets published in Nature and Science and PNAS (the Proceedings of the National Academy of Sciences). People get a press release. Russ: The New York Times. Guest: Yeah. They get a press release and there's a lot of funding in this area. And I call this climate model taxonomy because I don't have confidence in climate models on regional spatial scales, so I think the whole impacts game related to climate models is rather pointless. And also they really don't get that natural internal variability so they can't really say anything on time scales of 50 years. So I think there's this whole field of climate model taxonomy that's very well funded and gets all the headlines that is pointless scientifically. It's not increasing our understanding of anything and I think is fundamentally misleading to decision-makers because the climate models aren't good enough on those space- and time-scales. And so the newer generation of climate scientists broadly defined are seeing a lot of rewards in the climate taxonomy area, and it's relatively easy work. And I think it's, personally, pointless. It's not fundamental useful to the decision-makers and it's not increasing our fundamental understanding. So I'm not happy with the way all this is going. I have been Chair of the School of Atmospheric Sciences at Georgia Tech since 2002, and I've tried to do my hiring in what I would call the fundamental areas, trying to increase our fundamental understanding rather than what I would call climate model taxonomy. And there is pressure for me to hire 'climate modelers', not so much people who are working to develop fundamentally new types of climate models--I'd be definitely interested in that--but people who are just using the output of climate models. And I don't think that's a useful way for our science to go. So, I fight that on my own little square of turf. But it's very hard to find even good people to hire who are doing fundamental work. There's a lot of people in what I would call the 'chemistry aerosol cloud interactions' doing very fundamental work that I think is very exciting; and I think this is where a lot of the good physicists and chemists who are interested in climate are working in that area. So that area is very vibrant. But what I would call the more climate dynamics, the fundamental more fluid dynamics of the atmospheres and oceans, I've found it very hard to find good people who are making fundamental advances in our understanding. Russ: Well, I'm not surprised. Right? Those are the hard problems. When you are fresh out of graduate school you are told, 'Don't work on those; you won't get tenure. You might work for 10 years and get nothing and you're going to be out of a job. Guest: Exactly. You can get lots of publications and lots of citations by doing climate model taxonomy. So that's a concern that I have. And it's the older--I never thought I'd live to see the day when I am one of the old farts, the older generation, but a lot of the fundamental wave dynamics and fluid dynamics that was emphasized in the 1970s and 1980s--those people are on the verge of retirement. And in terms of even educating the new students in these areas--I'm just wondering where that's going to come from. So I am concerned about--and the awards that are given in professional societies. This past year I was on the Fellows Award Committee for the American Geophysical Union, and the first knee-jerk reaction is the look at the number of publications in the so-called H Index, which is related to people's scientific citations. Russ: That makes it scientific. Guest: Yeah, right. It's quantifiable. But the people who are working on the very hard problems and don't have that same kind of productivity or citations, it's harder to push them through. It's a lot harder to make the case. And personally I work hard to make the case for people who I think are doing a good job in those areas. But again, the recognition is skewed towards number of publications, citations; and people who are doing something that catches the attention of the media. And again, climate model taxonomy is a very easy path to fame and fortune in climate science. But it's not getting us where we need to go, ultimately in terms of increasing our fundamental understanding and really giving decision makers something that they can use.
53:47Russ: So, let's look at the other side. So, same thing happens in economics. If you can make a case for government intervention you are usually going to get invited to the better cocktail parties and you are going to be more--politicians are going to pay more attention to you and you are more likely, perhaps, to get quoted in the media, which is always pleasant and adds to your pocketbook in various ways--not directly but indirectly. And the grant-making obviously has something to do with that as well. And I look at climate science and I see that phenomenon and I see people who have the opportunity to be on the right side, the side that has the moral high ground right now, and I understand the incentives that people face in how to think about what to work on and what side they come down on, what evidence to consider. But on the other side, the climate advocates, the people who advocate intervention and action, they say, Well, it's just as bad or worse; they'll say it's worse on the climate skeptic side. Those folks, people who are skeptical about climate or think we don't know what we're talking about or talk about complexities as you do, they are just pawns of industry. They are people who get a lot of money from, typically, the fossil fuel industry and they are just saying what they are paid to do, and of course being paid by an oil company is much worse than being paid by the EPA or a government agency in terms of prestige. So, what's your response to that? Maybe you are one of them. Maybe you are a pawn of industry, Judy. I like you, you seem nice; and I want to believe what you say; but maybe you have the same issues. Is that true? And do you think that's true--people who generally are skeptical about climate? Guest: Okay. I think this whole 'pawns of industry' thing is just a red herring. The Merchants of Doubt, a book by Naomi Oreskes--she identifies some people like Fred Singer and people that really aren't big players in the public debate on climate change at this point. The only person that I know that's making money off of being a climate skeptic is Pat Michaels. He's managed to make money off of it. That's not his primary motivation, but he has managed to make money off of it. Russ: And it doesn't mean he's wrong, by the way. I think it's always important when you point out these things--it's an interesting argument; it's not decisive. Guest: It doesn't mean he's wrong. He's just sufficiently, how shall I say, stubborn, loose cannon, say-what-he-thinks. He's not going to be bought by anybody. But what he says is found attractive by certain people and he's attracted some money that way. So, Pat Michaels is the only person that I know of that makes money off of this. In the interest of disclosure, I--my company, Climate Forecast Applications Network--the target of a lot of what we do is the energy sector. But it's really short-term weather forecasting, time scales of days to weeks. And so there's nothing that I do for the energy sector that has anything to do with climate change and I don't think any of my clients have ever actually even asked me about climate change, although I know a few of them follow the blog. So, I do have some contracts with regional power providers and even one big energy company to do short range weather forecasting--of heat waves, of hurricane landfalls, things like that, that are of relevance to the energy sector. But my position either way, the one big oil company--actually this contract started in 2006; and we got this contract, they were attracted to our position on hurricanes and global warming, a big paper that we had published from Georgia Tech where we saw an increase in the percentage of Category 4 and 6 hurricanes; and they thought that we had some new insights to understand how to predict hurricanes. So that actually attracted them to us in the first place. Although what we ended up doing for them actually had nothing to do with global warming. And since then my position has shifted to be more skeptical about the global warming issue. So ironically the contract that we have with a big oil company was originally attractive by the position that we had that warmer temperatures were causing an increase in hurricane intensity. So, that's a full disclosure of my connection with oil companies. But my opinion about global warming obviously has nothing to do with the fact that I have some oil company clients. So I think that to me that is a big red herring, this issue, that the scientists that I talk to--and there are many people that do not make public statements about global warming but remain quite skeptical of the IPCC, but they don't speak publicly because, among other reasons, they have no inclination to. But they also see what happened to me when I spoke out on this issue, in terms of being labeled a denier and a heretic, and they don't want to, you know, bring that sort of thing down upon their own head. Russ: I think the whole issue of the social factors are quite significant, beyond the monetary ones. The IPCC is just the Intergovernmental Panel on Climate Change, for those of you who want to look it up on the web. It issues reports on the state of the climate and makes policy recommendations as well.
59:58Russ: So here's the interesting question, and we're almost out of time. Let's suppose you are a paid--not you have a contract with a big oil company to work on short term meteorological stuff. But let's say you are a consultant for the oil company, a spokesperson. Now, in theory that doesn't change any single thing that you've said so far today. Right? Everything you've said so far today, you've said, intending at least, as far as we can tell, to be spoken as a scientist. The problem of course is that those of us out here in the hinterland, just as it is in economics as well--we don't know very much. So we look for experts. And my general rule is that all experts are biased. It may not be monetary. It may be intellectual; it may be ideological. Everybody's got baggage. And the way we assess truth isn't by saying, 'Well, who has got the least baggage, because they must be telling the truth.' The way we assess truth is by asking whose evidence stands up, whose evidence proves correct, whose theories are confirmed, whose are challenged, etc. But the problem is for those of us who are just mere citizens and not your fellow scientists, what's a citizen to do? People ask me this all the time about economics. They say, 'Well, there are all these different theories of economics. Which on is the right one?' And I'm always tempted to say, 'Just pick one that feels good, because you'll find some evidence for it and you'll feel like you are doing the right thing. But that's really not what we want to do. We really like to know what is really true. So, what's your advice for people out here--we are not specialists--who are not trained formally in climate change or even in data analysis? How do you find out what's real and what's not real? How do you find out something close to the truth? Guest: I think again, I think the framing of the wicked problem is useful here. It's so complicated that we don't really understand it very well. We understand aspects of it but there are aspects that we don't understand, and we continue to be surprised by what nature dishes out in front of us. Again, I think this is why the wicked problem is a useful one for framing to the public. And in terms of biases, I think--and I write a lot about the social psychology of science and understanding bias and trying to weed out biases and trying to identify them. I've been reading that literature for the last maybe 3 years ago, basically, since I've been working on the blog a lot. And it's really illuminating to me to try to uncover my own biases. We all have them. And I think self-awareness by scientists and by members of the public is an important thing. So trying to understand your own biases and be aware of them; and hidden biases--'Oh, I didn't think that would be a source of bias but now that I think about it, it probably is.' So, everybody has biases, but it's the job of scientists to try to weed those out and be as objective as we possibly can. So I view it as this is part of the scientific process, to try to weed out our biases and be as objective as we can. And when you hear disagreement and debate about an issue such as climate change, again the conflicts are not only over science, but they are also about values. And they are also about politics. And sometimes these things get hopelessly mixed up. And I would argue that in the climate change debate, values, politics, and science have gotten rather muddled. Not just in the public debate but even in the minds of scientists. So again there's no simple solution. And if you are interested in trying to understand this issue better I encourage you to engage with some of the blogs. Pick a couple of blogs and read the posts and the comments and even consider participating. I think a lot of people who engage in the blogs and participate in the discussion do learn a lot of things about the science itself and also about the public debate and the political tradeoffs. And a lot of people, even though they are partisan and incline toward one side or the other, I think a lot of the people who are partisan also do check out some of the opposing blogs just to see what's going on. And it's a check. So I think the blogosphere is really an interesting development that can help people engage and understand what the debate and controversies are all about. Russ: Yeah, I totally agree with you. You have to pick them wisely; you have to pick, ideally, some people on both sides of an issue and see what people say and how they talk about it. Your remark about self-awareness strikes a chord with me. As listeners will know, it reminds me of this wonderful quote from Richard Feyneman: The first principle is that you must not fool yourself, and you are the easiest person to fool. It's good general advice that we should be aware of our biases. I think one way to do that is just don't read the ones you already agree with. Guest: Agreed.

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