David R. Henderson  

Partial Reply to Yoram Bauman

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Bauman Responds on The Cart... Half-Staff for Farmers...

UPDATE BELOW

Co-blogger Bryan has graciously published Yoram Bauman's response to Bryan's critique of his The Cartoon Introduction to Climate Change. As Bryan notes, he will not be able to get around to responding to Yoram soon, and so I will cover a couple of the issues that Yoram addresses.

Specifically, I want to answer the questions that Yoram raises in his 7th paragraph. Yoram writes:

Are you comfortable saying that carbon dioxide is a greenhouse gas? That human emissions of carbon dioxide are raising atmospheric CO2 concentrations? That global temperatures have been increasing over the past century? That humans are partly responsible for those increasing global temperatures? That "it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century"?

Here are my answers.

Yoram: Are you comfortable saying that carbon dioxide is a greenhouse gas?
David: Yes.
Yoram: That human emissions of carbon dioxide are raising atmospheric CO2 concentrations?
David: Yes.
Yoram: That global temperatures have been increasing over the past century?
David: No. "Have been" implies not only that they have increased but also have increased in the recent past. Global temperatures have increased over the past century. Of that fact, I can find no dispute, no matter which side of the issue climate scientists are on. But global temperatures have not increased for over a decade.
Yoram: That humans are partly responsible for those increasing global temperatures?
David: If you had asked it probabilistically, e.g., "That humans are likely to be partly responsible for those increasing temperatures," then yes.
Yoram: That "it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century"?
David: No. In asking the question, Yoram focuses on the IPCC report as his source. But a search of the literature by Cook et al finds that only 64 of 11,944 abstracts of articles by climate scientists conclude that humans are responsible for over half of global warming.

BTW, I was frustrated when I clicked on one of Yoram's links. He wanted to direct us to his debate with Steve Levitt, but when I went to the link above and clicked on the link on his exchange with Steven Levitt, it didn't work. Yoram, perhaps you could provide a link that works?

UPDATE

Commenter Daniel Kuehn suggests, quite rightly, that I refer to better data on scientists' opinions about the effects of humans on global warming. My only point in referencing my 1.6% number was to show the number one gets when one uses Cook's own methodology. But a better number is this one: 52% of meteorologists who responded to a survey thought that humans are the main contributors to global warming.


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COMMENTS (32 to date)
Josiah writes:

But a search of the literature by Cook et al finds that only 64 of 11,944 abstracts of articles by climate scientists conclude that humans are responsible for over half of global warming.

So what? If you searched through the abstracts of papers by economists, only a small percentage would explicitly affirm that restrictions on free trade are economically inefficient. But that hardly means there isn't a consensus among economists that restrictions on free trade are economically inefficient.

As Mark Bahner put it in a comment on your original post:

let's get something straight: the paper is junk.... BUT...that doesn't mean that there isn't a substantial amount of agreement that humans have caused most of the warming observed since 1950. Which renders the title of this blog post hilariously inaccurate hyperbole. (You really should put a "wink" after the headline, David. :-))

August writes:

Some German researchers pointed out a while back that we don't live in a greenhouse. We live on Earth, where the atmosphere expands and contracts depending on a variety of conditions. CO2 is certainly important in a greenhouse, because plants need it, but it is not crucial to this false meaning- i.e. most gases would function as a 'greenhouse gas' in a greenhouse because the real mechanism of a greenhouse is the glass allowing sunlight through and simultaneously keeping the gas trapped. The application of energy (photons) to trapped gas will result in heat.

If one were going to use the term 'greenhouse gas' appropriately, it would be used as a positive adjective, since gases found in greenhouses have to be conducive to growing plants.

Ted Levy writes:

Especially interesting would be a back-and-forth between Yoram and David Friedman, who has a physics PhD and some interest on this topic, in addition to dabbling in economics.

Joel Aaron Freeman writes:

The Whole World says: "We all must do this!"

And then Econlog replies: "Well, what are your arguments?"

Econlog, thank you for existing.

Daniel Kuehn writes:

David -
Recall the discussion in that link on 1.6% vs. 97% and some additional data that Mark brought to the table. Most of the 11,944 papers did not say that because they did not weigh in on the question at all, not necessarily because they disagree with the affirmative claim the 64 made.

Mark suggested:

"Why not simply accept the AMS survey paper as a reasonable approximation of current thinking:

"Is global warming happening? Absolutely! 98%-99%
Are we an important cause? Yes! 85%-93%
Are we “the” cause, as in is it mostly human? Yes. 75%""

Which seems quite reasonable to me based on my (limited) knowledge of the views of climate scientists.

David R. Henderson writes:

@Joel Aaron Freeman,
Econlog, thank you for existing.
To the extent I’m responsible, you’re welcome. And thank the late Mr. Goodrich too.

Charley Hooper writes:

@Daniel Kuehn,

While it might be true that most climate scientists believe those things, that doesn't necessarily mean they are right. Most people believed the world was flat. Most doctors believed that bleeding a patient improved his/her health. Even today, there are a whole bunch of things that people believe that are just plain wrong.

We have to consider how these scientists got to that conclusion. With my little research into this matter, I've been shocked how crude are the models and assumptions that lead to these results. I know someone who's a true believer and he works in this area. He can complain for two straight hours about the methods and he has been finding huge errors himself.

Most importantly, climate scientists are not economists. So even if the earth is warming and even if humans are a cause, the best actions to be taken cannot be ascertained without a whole cost/benefit analysis, the proper application of probabilities, and an awareness of how economies grow and react to such situations. The economic assumptions that the IPCC people are using are just plain wrong.

Josiah writes:

While it might be true that most climate scientists believe those things, that doesn't necessarily mean they are right.

That's true, although a lot of people seem to have trouble even admitting what most climate scientists do believe, which is not exactly an encouraging sign.

MingoV writes:

Here's a concept no one pays any attention to in the climate debate: CO2 is a greenhouse gas when it is in a greenhouse. The entire greenhouse gas concept is based on geometry. In morning and afternoon, a solar photon can pass through roof and sides of a greenhouse without hitting anything. That photon doesn't warm the greenhouse, it warms the area outside the greenhouse. When greenhouse air has lots of greenhouse gases (mostly water), some of those solar photons are captured by the air and warm the greenhouse. Correspondingly, the area around the greenhouse does not get warmed by that photon. Mean temperature of the area does not change.

The surface (and lower atmosphere) of planet earth has no inside and outside. There is no enclosed glass-sided, glass-roofed building around the planet. All the planet is outside. If a solar photon is captured by the air, it warms the planet. If the photon hits the ground or the ocean, it warms the planet. CO2 in the air doesn't magically capture extra solar photons. This whole greenhouse-gas based planetary warming concept is magical thinking.

(Yes, I know plenty of scientists believe otherwise, but most of them haven't thought it through. They need to read a physical chemistry 101 textbook.)

Daniel Kuehn writes:

On the update:

1. Does anyone know why David's chosen number is so different from other surveys you hear about? Is it question wording?

2. David - what do you like better about this survey compared to the ones in the 70/80/90 percent ranges?

bill writes:

Global Temps haven't risen in over a decade: but they've been holding a new plateau. That's not good. They didn't revert to a mean.

Probabilistic thinking: I would hope that even a 1 in a thousand chance of serious human misery would warrant a $5 or $10 gas tax etc, especially when the proceeds could eliminate the income tax on 80% or more of the people.

Charley Hooper writes:

@MingoV,

The whole greenhouse concept is based on light changing from one form of energy (ultraviolet) to another (infrared). For instance, when light enters your car through the windshield, the glass converts it from ultraviolet (visible light) to infrared (heat). That infrared energy cannot exit the car through the windshield because the glass blocks infrared energy.

Greenhouse gases work the same way, converting light from one type of energy into another. They are called greenhouse gases because their effect on light is similar to that of a greenhouse.

If there were no atmosphere, like on the moon, the light energy would hit the planet and then return to space. The atmosphere holds that infrared heat. Theoretically, the more greenhouse gases, the more heat builds up. Of course, earth's climate is a complex system.

Charley Hooper writes:

@bill,

What if there's even a one in a thousand chance of wondrously great things that come from a slightly warmer planet? A warmer planet has some probability of bad outcomes and some probability of good outcomes. Both sides must be considered.

Also, we must consider the downside of a tax on carbon. Once we do that, reasonable people might conclude that the tax is harmful.

MikeP writes:

I would hope that even a 1 in a thousand chance of serious human misery would warrant a $5 or $10 gas tax etc, ...

I have to assume that you have no idea that the economically justifiable gas tax, e.g., from William Nordhaus's work, is closer to 35 cents.

A $10 gas tax is serious human misery.

libfree writes:

David,

I can't personally rate the scientific credibility of these claims but there is debate about the warming or the amount of warming. surfacestations.org has been cataloging the changes in the environments that the thermometers located. If a thermostat gets surrounded in black top, its probably going to start reading higher temperatures.

Other concerns involve modern thermometers that are more accurate and are more reliable over time. How much can you trust thermometers from 50 or 60 years ago? How well were they maintained? If you can't accurately determine their error, how can you control for it?

The "hide the decline" controversy revolved around tree ring data diverging from observed data. That should make us question tree ring data in general rather than deciding that its an abnormality??? The big deal is that we don't know how to rate old temperature data over time.

David Barry writes:

@Daniel Kuehn,

The 52% figure is from a survey of meteorologists, not climate scientists. The subset of those meteorologists who publish in climate science have 70-80% agreement with mostly human-induced warming.

Josiah writes:

@libfree,

In addition to land based temperature readings (which might be subject to a heat island effect) there are also satellite readings, ocean readings, temperatures taken from balloons, etc. All of them show warming over the past century.

August writes:

Charlie Hopper,

You make an erroneous logical leap from the glass in a windshield to the gas in a greenhouse. It is much more appropriate to assume the glass in the greenhouse is similar to the glass in the windshield, and the gases are largely recipients of the energy. In a greenhouse, the energized gases are trapped and temperatures rise. In the open atmosphere gases are able to diffuse. The entire atmosphere can expand and contract, depending on energy input in the sun.

Eric writes:

I have to assume that you have no idea that the economically justifiable gas tax, e.g., from William Nordhaus's work, is closer to 35 cents.

This is another major issue. The gas tax is higher than this in every U.S. state except Alaska and New Jersey:

http://en.wikipedia.org/wiki/Fuel_taxes_in_the_United_States

In addition, every other tax (including multiple taxation via corporate income taxes, capital gains taxes and taxation of dividends) slows economic activity and therefore reduces CO2 emissions. Even Nordhaus's use of a too-low discount rate combined with publication bias toward negative effects of warming suggests that we should lower our taxes, not raise them.

Daublin writes:

I think Bryan is right to encourage an economic perspective. It's a neglected part of the debate. In particular, it's helpful to consider cost-benefit analysis, and it's helpful to consider when insurance is a good buy.

Particularly salient in my mind is that once you consider uncertainty, there are too many potentialities for insurance to make much sence. Maybe an ice age will come sooner than expected. Maybe asteroid impacts are more likely than currently believed. Maybe the sun flares up every 100k years, too infrequently for it to be in the historic records. Maybe, yes, CO2 feedback is higher than expected. Maybe it is much, much, higher. Maybe it's not high enough.

When faced with this many unknowns, insurance doesn't work very well. Instead, it's better to keep and grow one's resources, so as to be ready no matter what happens.

Rich Berger writes:

Josiah-

You are incorrect. Satellite records go back to 1979 not over a century. More significantly,warming was shown up to about 97-98 after which there has been no warning. See -http://www.drroyspencer.com/latest-global-temperatures/

Josiah writes:

Satellite records go back to 1979 not over a century.

Sure, and they show warming over that time period.

Honestly, I don't understand why people are so insistent on making bad arguments against climate science when there are perfectly reasonable arguments against cap and trade or whatever. Why pick that hill to die on?

Josiah writes:

BTW, since you cited Roy Spencer, here is what he says in his "Global Warming Skepticism for Dummies":

over the last 100 years, there was an overall warming which was stronger toward the end of the 20th Century.

Eric writes:

Also from Spencer’s site: “The very fact that recent tree ring data erroneously suggests cooling in the last 50 years, when in fact there has been warming, should be a warning flag about using tree ring data for figuring out how warm it was 1,000 years ago. But without actual thermometer data, we will never know for sure.”

Emphasis mine. Recent tree ring data suggest cooling!

I’m at a loss as to why people think we have actual thermometer data. We have adjusted thermometer data.

The scientists doing the adjusting were actively unwilling to release data or programs under the Freedom of Information Act. CRU states on its website “Since the 1980s, we have merged the data we have received into existing series or begun new ones, so it is impossible to say if all stations within a particular country or if all of an individual record should be freely available. Data storage availability in the 1980s meant that we were not able to keep the multiple sources for some sites, only the station series after adjustment for homogeneity issues. We, therefore, do not hold the original raw data but only the value-added (i.e. quality controlled and homogenized) data.” That from their own website. And they've been unwilling to release the program for adjusting as well.

Source: http://www.cru.uea.ac.uk/cru/data/availability/

Here is just one example of the potential for bias in temperature adjustments:

http://wattsupwiththat.com/2009/12/08/the-smoking-gun-at-darwin-zero/

I realize this site won’t convince true believers, but hopefully I can convince those on the fence to check it out.

I choose this hill to die on because I actually believe it is about 45% likely that the data is in error due to consistent biases on the part of the researchers. Read the CRU emails. Please read them!

Tom West writes:

Charlie Hooper:

While it might be true that most climate scientists believe those things, that doesn't necessarily mean they are right.

True, but it's interesting that adherence to the expert opinion is pretty much a smoke test for rationality in the cases where we don't have an ideological interest in the experts being wrong.

It's sad, but predictable. We'll sneer at those who ignore the expert consensus in almost any field (Don't believe in evolution? Believe vaccines cause autism? Think economists don't understand economics?), but when it comes down to it, our we're exactly the same when the experts conflict with *our* basic beliefs.

When our fundamental beliefs come up against expert consensus, we know it's the beliefs that will triumph, and we'll come up with some rationalization as to why all those scientists are wrong. There's a very good chance we'll probably attribute evil motives to them as well ("they're doing it for the funding!").

As the quote goes, "We're not rational creatures, we're rationalizing creatures."

Most importantly, climate scientists are not economists. So even if the earth is warming and even if humans are a cause, the best actions to be taken cannot be ascertained without a whole cost/benefit analysis...

Now that is true. But what happens when the costs are borne by one group and the benefits accrue to another? There's no way we'll ever see intra-country transfers of that scale.

An interesting thought experiment is to try to establish what evidence would actually cause you to change your mind about this (i.e. what *would* make you believe urgent action to reduce emissions is required). If there isn't anything, then we're talking about faith, not reason.

Which is fine - we've all got our beliefs that aren't going to be budged. But perhaps we shouldn't come down as hard on others who's actions are also faith-based.

Roger Sweeny writes:

MingoV,

I don't like the terms "greenhouse effect" and "greenhouse gas" because what happens in the atmosphere and what happens in a greenhouse are significantly different.

The sun is very hot. Hot objects radiate electromagnetic energy at relatively high frequencies/short wavelengths (visible light and ultraviolet). There's a nice animation at
https://phet.colorado.edu/en/simulation/blackbody-spectrum
Click the green Run Now! button.

Electromagnetic radiation in the form of visible light and low frequency UV passes through the atmosphere fairly easily and is absorbed by the earth and warms it. In PhysicsSpeak, the atmosphere is relatively transparent to these frequencies/wavelengths.

The earth then radiates away the energy it has gained. But since the earth is considerably cooler than the sun, it radiates in lower frequencies/longer wavelengths, basically infrared. However, infrared does not pass through the atmosphere easily. Much of it is absorbed and that energy stays within the earth system. In PhysicsSpeak, the atmosphere is relative opaque to UV. The temperature of earth is thus considerably higher than it would be if there were no "greenhouse gases."

The most important "greenhouse gas" in the atmosphere is water vapor, with methane and carbon dioxide next in line. I think everyone agrees that "other things being equal," more CO2 means higher temperature. But, of course, other things are never equal. How much additional warming will be caused by additional CO2 is an empirical question, one that no one has a definitive answer to at the moment.

libfree writes:

@josiah I'm surprised that more AGW believers aren't concerned about data quality. Knowing that temperatures have risen over the last few decades is unimportant, AGW is completely based on historical information to let us know that this isn't a normal event.

Mark Bahner writes:

Daniel Kuehn (May 15, 1:24 PM) writes:

Mark suggested:

"Why not simply accept the AMS survey paper as a reasonable approximation of current thinking:

"Is global warming happening? Absolutely! 98%-99%
Are we an important cause? Yes! 85%-93%
Are we “the” cause, as in is it mostly human? Yes. 75%""

Which seems quite reasonable to me based on my (limited) knowledge of the views of climate scientists.

Exactly. (I think what I wrote was logical. Big surprise there! ;-))

A better way to look at the Cook et al. paper is that they look at many thousands of abstracts. But only 64 abstracts were in Category 1 ("Explicit endorsement with quantification"). So only those 64 abstracts can be legitimately claimed to fall into the characterization: "Earth is warming up and human emissions of greenhouse gases are the main cause." (Important caveat: This is taking them at their word...I'm very skeptical about anything in the paper, without having verified the 64 abstracts myself!)

And then there were apparently 9 abstracts in "Category 7: Explicit rejection with quantification."

So a reasonable assessment would be to only compare the number of Category 1 to the number in Category 1 and Category 7. That would be 64 out of 73, or about 88%.

P.S. Another possiblity would be to compare Category 1 to Category 7 *and* Category 6 ("Explicit rejection without quantification.") The results looking at it that way would be 64/(64+9+15) = 73%.

Mark Bahner writes:
The economic assumptions that the IPCC people are using are just plain wrong.

I maintain that the economic assumptions that virtually the entire *economics* profession are making will be shown to be "just plain wrong." And not by a little bit! I maintain that virtually the entire economics profession is going to be wrong *on the low side* about world per-capita GDP in the year 2100. And probably by a factor of 100:

World per-capita GDP will exceed $10,000,000 (year 2000 dollars) by 2100

This is because of the impacts of artificial intelligence on economic growth:

Why economic growth will be spectacular

Needless to say, if I'm right, it would have a big impact on how we should look at the damage from global warming (e.g. using a discount rate in social cost of carbon calculations in excess of 7% per year).

Todd Kreider writes:
Especially interesting would be a back-and-forth between Yoram and David Friedman, who has a physics PhD and some interest on this topic, in addition to dabbling in economics.

I don't think it would be especially interesting for Yoram to be crushed by a physicist.

Yoram Bauman writes:

Sorry for the broken link, David. It's fixed now. Here are my emails with Levitt.

David R. Henderson writes:

@Yoram Bauman,
Thanks.

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