Friday, December 18, 2015

How To Lie While Telling the Truth: Part II

My previous example was an attack on religion. This time it is a defense of AGW catastrophism.

It has long been known that increasing the concentration of CO2 increases the yield of C3 plants, including most crop species. The usual estimate is that doubling CO2 concentration, roughly what is projected for the end of this century, increases yield by 30% or more. This is an inconvenient fact for people who want to argue that AGW will reduce food supplies. Clearly what they need is a scientific article to cite, proving that CO2 is actually a bad thing for crops. 

And they have one, in Nature no less: Increasing CO2 threatens human nutrition.

 The article itself is behind a pay wall, but a good deal of its content is revealed in the abstract and various admiring news stories, including this one:

A quick google found the following table of minerals for wheat:

It includes ten minerals, zinc and iron among them. The fact that the authors of the article could find two whose concentration went down, not by very much, is interpreted as a threat to human nutrition. No information on any that went up.

It's worse than that. The figures, at least according to the news story and the abstract of the article, are for concentration. Increasing CO2 increases the yield of C3 crops. If the concentration of zinc goes down by nine percent but the total crop yield goes up by more than nine percent, total yield of zinc goes up, not down.

Further, the abstract makes it clear that the effect varies from one cultivar to another—so if there really is a problem with the concentration of zinc and iron, farmers will have an incentive to switch to cultivars for which there isn't.

If, with a doubling of CO2 (the abstract does not say what concentration was used in the experiments), crop yield goes up by 30% but the concentration of two minerals goes slightly down and the yield of protein only increases by 24%, that is a "threat to human nutrition."

A striking example of propaganda disguised as science.


[I have sent a message to the lead author of the article inviting him to respond here]


Another paper, not behind a pay wall, by many of the same authors. It makes it explicit that "we believe the simplest approach is to model diets that are unchanged with respect to calories and composition."


montestruc said...

Indeed I agree with you.

But for the sake of making yourself less vulnerable to accusations of bias, or hyperbole, presenting links to academic papers showing that indeed higher CO2 concentrations have substantial net positive effects such as:

One thing you could get called on is your assertion of 30% rise in crop yield for a doubling of CO2. Really you should qualify the statement as temperature, water availability, geography (indirectly affects temperature and water) and plant species are all variables in that issue, and temperature and water availability will be changed at any given location.

Again, I agree with you, but I feel like you are oversimplifying this and making your argument vulnerable to attacks that while technically wrong, will take more effort to correct than having your ducks in a row in the first place.

Josiah Neeley said...

The same authors have published data on all nutrients here:

David Friedman said...

Josiah: Have you read the article you cite? It gives raw data from lots of other people's experiments. But I cannot figure out how to extract the relevant figure--the change in nutrient concentration as a result of increasing the CO2 concentration.

Each line of the table lists an elevated CO2 and an ambient CO2, but there is only one figure for the amount of nutrient. What am I missing?

Josiah Neeley said...

If you download the excel data there is a column labeled CO2-Treatment (column AC). For each record in this column there is either "aCO2" (meaning ambient CO2) or "eCO2" (meaning elevated CO2). The eCO2 entries are for the crops that were exposed to higher CO2 levels. I believe you can derive the effect of increased CO2 for a nutrient, by taking the average amount of the nutrient for the aCO2 of each cultivar and comparing it to the average of the eCO2 records.

This would mean a fair bit of work, but presumably the authors hope that making the data available will encourage others to examine the effect of more CO2 on other nutrients as part of their own research.

Josiah Neeley said...

I would add: to the extent that increased CO2 does result in less nutrients, developing GMOs or using selective breeding to counteract this effect seems preferable to, say, trying to get societies to move from a rice based diet to a sorghum-based diet. Indeed, the last line of the abstract suggests this as a possible remedy.

For this reason (among others), I don't think it's fair to call this paper propaganda disguised as science.

David Friedman said...

Josiah: Thanks for your explanation--looks like a fair amount of work.

The title of the article is "Increasing CO2 threatens human nutrition." Do you agree that the title is propaganda--a blatantly dishonest description of the result of the paper? Lowering the concentration of two out of ten minerals by a small amount while increasing total yield, very possibly increasing yield of those minerals, does not threaten human nutrition. The only reason to say it does is to provide ammunition for people who want to evade the very clear evidence that increasing CO2 improves human nutrition by increasing food supplies.

Let me put it in numbers, assuming their experiment doubled CO2 concentration. Their result is that doubling CO2 results in a field of wheat producing about 30% more carbohydrate, 24% more protein, 21% more zinc, 25% more iron, and about 30% more of all the other minerals in wheat. And this is described as "threatens human nutrition."

Benjamin. said...

Do you know of any other time in history that the academic science community has so forcefully pushed an idea that turned out to be wrong? Obsession with Global Warming seems almost cult like...
I can't imagine someone like Richard Feynman, for example, ever name-calling someone disagreeing with him on ANYTHING.

David Friedman said...


Concern with overpopulation would be an earlier example of a similar pattern.

Roger said...

It would have been a great experiment if the authors drafted two versions of the paper, one emphasizing the positive effects, and one the negative. Then see which gets accepted for publication in a major journal.

My hunch is that the authors are not necessarily biased. They are just putting the paper in a form suitable for publication.

Tibor said...

Benjamin: A great part of the academia was convinced that communism is the way to go in the early 20th century. Interestingly enough, if Hayek is to be believed, it was on the side of "exact sciences" and maths that this conviction was strongest whereas the social sciences of the time were not so enthusiastic about communism. For some reason, the situation is the other way around today, with social sciences being in general more socialist (with the quite obvious exception of economics). Maybe it is that the dogma has shifted - nobody thinks any more that we can "order the wind and rain" and in a lot of physical sciences you have quite nice examples of "spontaneous order". On the other hand, social sciences used to be more about "the nature of man" and shifted towards "how everything is a social construct and therefore malleable to an arbitrary degree" (I am simplifying a bit).

Although, technically am I am part of academia at the moment (although, I don't know if I count, being a PhD student), from what I have seen it has not made a great impression on me. Or to be less bombastic - there is surely some good research done but also a lot of bad research and a lot of internal as well as external politics influencing the process (the external more in fields that are related to politics, such as economics or climate science, less in maths). I wish that one day "regular people" would not go "oh, you have to be a genius" just because you have a PhD, if possible ignore the titles altogether and focus on the content and the arguments. Once you see how easy it is to get a PhD in some fields, you lose all respect you might have had for the title "scientist". But I won't hold my breath.

Unknown said...

Congratulations David on the 10th anniversary of your blog.

Josiah Neeley said...

Prof. Friedman,

I want to be clear that I haven't read the paper in question. My understanding is that you haven't read it either and are going off what is/isn't in the abstract and press accounts. This seems to me to be a dangerous strategy when the criticism is that the paper didn't deal with a given issue.

As montestruc said above, the 30% increase in yields from a doubling of CO2 assumes no change in temperature or water availability. But a doubling of CO2 is itself expected to affect temperature and water availability, in some regions quite substantially. So one can't simply assume that increased yields would cancel out the effect of lower nutrient content. I don't know to what extent this issue is treated in the paper.

Similarly, I don't know what effect increased CO2 has been found to have on nutrients other than zinc and iron. However, if I don't get enough zinc and iron in my diet I'm going to have nutritional problems regardless of how much I boost my intake of other minerals. Given that several billion people already don't get enough zinc and iron, calling a decrease in those minerals a threat to human nutrition seems perfectly justified regardless of the effect on other minerals. Again, not having read the paper, I can't speak to how these issues are treated.

Anonymous said...

Unless all nutrients go up in exactly the same proportion, there would be something left behind for the pessimists to gripe about. Obviously, the people calling this a "threat to human nutrition" are hypercritical crybabies.

More generally, according to such a hypercritical attitude, any improvement in any specific sector of the economy would be "a threat to human nutrition" if it has the ultimate effect of increasing food production in any uneven way -- not increasing all nutrients in exactly the same proportion. These critics are neglecting the fact that resources are fungible, to a great extent, and the economy can self-adjust to fix imbalances.

If climate change increases wheat production by 30%, with no increase in cost of inputs, this means you can devote less resources to wheat production. The freed-up resources could be put to use, for example, in finding ways to add zinc to people's diets, were this found to be desirable.

David Friedman said...


You are correct--I am going on the abstract and the news story.

I don't see that increasing carbohydrate by 30% and iron by 25% would result in your not getting enough iron in your diet. Taking the argument seriously, any random change in the ratio of minerals to calories, with average effect zero, makes food less nutritious, since something is almost certain to go down. That makes no sense to me.

Given the tone of the news story, I assume that if other minerals had gone down noticeably it would have been mentioned. The data to check that are available, as you pointed out--perhaps you would like to try.

The paper is about the effect of the increased CO2 concentration, not about effects of climate changes that might be caused by it--which would be different in different places.

My complaint is not that the paper did not deal with a given issue, it is that the title of the paper misrepresents what the paper found. As does the news article based on the paper.

Colombo said...

They have it all wrong. The correct propaganda bit would have been "CO2 threatens human health because of superbacteria". The rationale is: more plants mean more insects, bacteria, viruses, fungi and all kinds of pathongens that we, and our domestic animals, may not be acquainted with. A golden age for plants may also mean a golden age for creepy critters that would become stronger and resistant to today's antibiotics, because of better nutrition. The nutritive factor affects everyone who feeds on plants, not just humans. This conjecture I've just formulated is far more passable than the one presented by these hacks. But even if what I say may seem possible, it may also turn out to be bogus. Perhaps the effect would be the opposite: stronger plants may seem more succulent to pathogens and may leave animals for a while.
Also, plants do not grow in order to be food for humans. They grow in order to reproduce themselves. They may develop poisonous substances to protect themselves. Humans like to grow weakened plants, but there are many things they can't control about their growth. What if several domesticated plants, like wheat, would spontaneosuly develop a bizarre protein that changed the flavor and texture of our bread?
And one last thing, what if plants, as we know them, have fewer minerals in them than they "should" only because their roots are weaker and shorter than they should have been, and that is because in the last four thousand years the atmosphere has been lacking in CO2 and water? Minerals are absorbed by the roots, not by the leaves. It seems logical to say that less mineral absorption may be caused by defective roots, not only because of a depletion
of minerals in the soil.

I would recommend to all quixotic scientists to stay away form politics as much as possible. If you are bored or frustrated with your field, change fields, take up a hobby or start teaching, but, please, do not try to save the world from your ghosts. And do read the Hippias Minor dialogue. If the humanity needs salvation from something, it is probably from politics, not from nature. Nature tends to be self correcting. Politics, not being a subject to nature, tends to be a promoter of chaos. So, less politics to everyone. Thanks.

Remember that futile works lead to melancholy.

RKN said...

Why rely on an abstract and a pop news story? You're a professor at a University with research departments (physics, biology, etc.) that no doubt have free access to scientific articles in journals like Nature. Shoot the chair of the biology department an e-mail, I'm sure she'd be happy to download the entire pdf and send it to you.

alaska3636 said...

The presentation of AGW, perhaps moreso than AGW itself, should present a serious conundrum to curious observers. Given the nature of the ratchet effect in government, given the near uniform presentation of AGW as a threat that demands greater government oversight, and given the close relationships between industry, the industry titans who own the media and the revolving door, crony marketism that exists here in the USA (probably elsewhere too), the whole thing looks like globalism plain and simple.

Government seeks to expand; in doing so and given its democratic shackles, it seeks problems for which greater government can be justified in order to solve this perceived problem (often called a market failure); industry titans back greater regulations given the opportunity to co-create it and raise the ladder to competitors; media marches in unison in its portrayal of this fiction. Whether globalism is a cabalistic conspiracy or a simple facet of human nature to constantly expand power when given the opportunity is another question.

Regardless of the threat of AGW, people should be wary of the nature of politics and the radical danger of centralized force in accumulating risk in the system. The problem with initiations of force isn't necessarily moral, but in concentrating the danger of implementing solutions without regard to the nature decentralized knowledge and unintended consequences. The threat of AGW is not clear; the threat of large regulatory bodies with the power to initiate force are historically clear.

David does a fantastic job of analyzing the presentation of AGW.

I wonder, David, whether you think the ratchet effect is being directed consciously or not? And whether AGW represents to some degree an aspect of this ratcheting?

Power Child said...

@David Friedman:

Thinking about the AGW stuff, and similar cultlike-fears-that-turned-out-to-be-wrong in the past, I wonder if it is in fact a useful instinct that is simply suffering from a lack of integration with other facts.

There is a good reason to be cultlike about environmental preservation: it's a public goods problem in which a whole lot of people don't mind polluting the environment for personal gain--and there are many who can't afford not to. If freezing current CO2 levels is possible, then one can argue it should be done simply because we don't know whether an Earth with more CO2 and higher sea levels would be net worse, but we do know that current CO2 levels and sea levels can sustain life as we know it. (Or something.)

Now I certainly disagree that scientists should take this approach--their job is to develop and test hypotheses--but journalists and activists are under no such obligation to the truth. (Though journalists ought to stop pretending otherwise.)

I'd love to see the same cultlike persistence applied to Ludditism. In my opinion we could use more people vehemently arguing against the use of cell phones, social media, wearables, GPS, and so on. Not because their arguments would be full of irrefutable scientific truths, but because these technologies are changing our society's values in ways we can't predict but which could be disastrous (see the AI risk debate). Since we know what our values are now, we can address them and work with them, even perfect them. But technology leads us down a blind path.

montestruc said...

I think you did not read the papers I posted. Several of them noted that increased CO2 made the plants more robust in the face of lower water or elevated temperature.

Tom Bridgeland said...

The very first order of business in improving nutrition of the very poor is to increase calories. Once that is done other things become important, proteins, then fats and micronutrients. In the example given, wheat yields are substantially increased, and I assume also other starchy foods. Once basic starvation diets are improved and calorie needs are met, you start adding higher protein foods, soybeans, other beans and the like.
My point is that if calorie needs are being met more easily, you simply increase the percentage of more nutritious foods in the diet to improve total nutrition. Instead of eating a diet of mainly starch, as starving people traditionally had to do, they can eat a diet with a higher percent of nutrient-dense beans, thus improving the total nutrient level in their diet.
It doesn't matter one bit if they are eating beans slightly lower in some random nutrient, as long as they are eating MORE BEANS than before. The increased volume of beans at the expense of empty carbs results in a better diet.

brazil84 said...

This seems to be a link to the full paper:

It's funny that the last couple pages are full of caveats and disclaimers.

David Friedman said...


That's an article most of whose authors are also authors of the one I pointed at, but I don't think it's the same article. It does, however, confirm my interpretation of what they were doing:

" Because of this complexity, we believe the
simplest approach is to model diets that are unchanged
with respect to calories and composition, an achievement
that many would consider optimistic in the face of rapidly
changing environmental conditions."

In other words, they are deliberately ignoring the effect of increased crop yield, assuming that people eat the same number of calories of the same foods, and concluding that they will get less zinc since the ratio of zinc to calories is now lower. Their excuse for doing so is that things other than the effect of CO2 might hold down food consumption--but it's the CO2 they are blaming.

Tom Bridgeland said...

They seem to be saying that maintaining current diet levels will be unlikely. Implying it at least. Given long term trends, that doesn't seem likely to me. Farmers plant only what they can sell, and production has always kept up so far. Except Africa, birthrates are falling pretty much everywhere.

Anonymous said...

There is a more substantive paper that shows how CO2 influences concentrations of various minerals in crops. Turns out, the journal it is published, eLife, is open-access:

"Hidden shift of the ionome of plants exposed to elevated CO2 depletes minerals at the base of human nutrition"

It appears both papers follow on the idea advanced by Loladze back 2002 at Princeton: