Wednesday, February 26, 2014

A Climate Falsehood You Can Check for Yourself

One problem in arguments about climate (and many other things) is that most of the information is obtained at second, third, or fourth hand, with the result that what you believe depends largely on what sources of information you trust. One result is that people on either side of the argument can honestly believe that the evidence strongly supports their view. They trust different sources; different sources report different evidence. It is thus particularly interesting when on some point, even a fairly minor one, you can actually check a claim for yourself. I believe I have found an example of such a claim.

Cook et. al. (2013) is the paper, possibly one of two papers, on which the often repeated claim that 97% of climate scientists support global warming is based. Legates et. al. (2013) is a paper which criticizes Cook et. al. (2013). Bedford and Cook (2013) is a response to Legates et. al. All three papers (the last a pre-publication version) are webbed, although Legates et. al. is unfortunately behind a pay wall.
Bedford and Cook (2013) contains the following sentence: "Cook et al. (2013) found that over 97% endorsed the view that the Earth is warming up and human emissions of greenhouse gases are the main cause."
To check that claim, look at Cook et. al. 2013. Table 2 shows three categories of endorsement of global warming reflected in the abstracts of articles. Category 1, explicit endorsement with quantification, is described as "Explicitly states that humans are the primary cause of recent global warming." Category 2 is explicit endorsement without quantification. The description, "Explicitly states humans are causing global warming or refers to anthropogenic global warming/climate change as a known fact" is ambiguous, since neither "causing" nor "anthropogenic global warming" specifies how large a part of warming humans are responsible for. But the example for the category is clearer: 'Emissions of a broad range of greenhouse gases of varying lifetimes contribute to global climate change.' If human action produces ten percent of warming, it contributes to it, hence category 2, as implied by its label, does not specify how large a fraction of the warming humans are responsible for. Category 3, implicit endorsement, again uses the ambiguous "are causing," but the example is '...carbon sequestration in soil is important for mitigating global climate change,' which again would be consistent with holding that CO2 was responsible for some but less than half of the warming. It follows that only papers in category 1 imply that "human emissions of greenhouse gases are the main cause." Authors of papers in categories 2 and 3 might believe that, they might believe that human emissions of greenhouse gases were one cause among several.
Reading down in Cook et. al., we find "To simplify the analysis, ratings were consolidated into three groups: endorsements (including implicit and explicit; categories 1–3 in table 2)." It is that combined group, ("endorse AGW" on Table 4) that the 97.1% figure refers to. Hence that is the number of papers that, according to Cook et. al., implied that humans at least contribute to global warming. The number that imply that humans are the primary cause (category 1) is some smaller percentage which Cook et. al. do not report.

It follows that the sentence I quoted from Bedford and Cook is false. Cook et. al. did not find that "over 97% endorsed the view that the Earth is warming up and human emissions of greenhouse gases are the main cause." (emphasis mine). Any interested reader can check that it is false by simply comparing the two papers of which Cook is a co-author. John Cook surely knows the contents of his own paper. Hence the sentence in question is a deliberate lie.

That Cook misrepresents the result of his own research does not tell us whether AGW or CAGW is true. It does not tell us if it is true that most climate scientists endorse AGW or CAGW. It is nonetheless interesting, for two related reasons.

In recent online exchanges on climate, I repeatedly encountered the claim that 97% of climate scientists believed humans were the main cause of global warming. That included an exchange with one of the very few reasonable and civil supporters of the CAGW claim that I encountered in the online arguments, where most participants on either side are neither. So far as I know, the paper says nothing that is not true. But it appears designed to encourage the misreading that actually occurred. It does so by lumping together categories 1-3 and reporting only the sum and by repeatedly referring to "the consensus" but never stating clearly what that consensus is. 

The closest it came to defining the consensus is as the "position that humans are causing global warming," which leaves it unclear whether "causing" means "are one cause of," "are the chief cause of," or "are the sole cause of." To discover that it meant only the former, a reader had to pay sufficiently careful attention to the details of the paper to notice "contribute to" in the example of category 2 in Table 2, which few readers would do. The fact that Cook chose, in a second paper, to misrepresent the result of the first is pretty good evidence that the presentation of his results was deliberately designed to mislead.

There is a second, and more important, reason why all of this matters. Beliefs on either side depend largely on what sources of information you trust. I have now provided unambiguous evidence, evidence that anyone on either side willing to carefully read Cook (2013) and check what it says against what Bedford and Cook claims it says can verify for himself, that John Cook cannot be trusted. The blog Skeptical Science lists John Cook as its maintainer, hence all claims on that blog ought to be viewed with suspicion and accepted only if independently verified. Since, as a prominent supporter of the position that warming is primarily due to humans and a very serious threat, Cook is taken seriously and quoted by other supporters of that position, one should reduce one's trust in those others as well. Either they too are dishonest or they are over willing to believe false claims that support their position.

The fact that one prominent supporter of a position is dishonest does not prove that the position is wrong. For all I know, there may be people on the other side who could be shown to be dishonest by a similar analysis. But it is a reason why those who support that side because they trust its proponents to tell them the truth should be at least somewhat less willing to do so.

P.S. A commenter has located the data file for Cook et. al. (2013). By his count, the number of articles classified into each category was:

Level 1 = 64
Level 2 = 922
Level 3 = 2910
Level 4 = 7970
Level 5 = 54
Level 6 = 15
Level 7 = 9

The 97% figure was the sum of levels 1-3. Assuming the count is correct—readers can check it for themselves—that 97% breaks down as:

Level 1: 1.6%
Level 2: 23%
Level 3: 72%

Only Level 1 corresponds to "the Earth is warming up and human emissions of greenhouse gases are the main cause." (emphasis mine) Hence when John Cook attributed that view to 97% on the basis of his Cook et. al. (2013) he was misrepresenting 1.6% as 97%. Adding up his categories 5-7, the levels of rejecting of AGW, we find that more papers explicitly or implicitly rejected the claim that human action was responsible for half or more of warming than accepted it. According to Cook's own data.

Would anybody now like to claim that lumping levels 1, 2, and 3 together and only reporting the sum was not a deliberate attempt to mislead?

P.S. John Cook eventually responded to my criticism, not here but on the comment thread of another blog that linked to this one. See his response and my comments on it here.

Very Good News

It looks as though there is now a cure for at least one category of leukemia--88% complete remission via gene therapy. With luck, the approach will prove workable for other forms of leukemia and eventually other cancers. Current cancer treatments are a brute force approach—we may finally be getting something better.

Having lost one friend to leukemia some years ago, another nearly fifty years ago, and three to other cancers, I see this as very good news.

A Good Economic Argument From My Favorite Webcomic

Indeed, the only one I read with any frequency. Pointed out by a commenter on my previous post.


Tuesday, February 25, 2014

Air and Sea: A Very Simple Model

Thinking about recent arguments on climate, I have been trying to work out the logic of the air/sea interaction in order to make sense of the pattern of warming. My current conclusion is that, on a very simple model, what we observe is qualitatively about what we would expect if at some point around the year 2000 net energy input to the system had for some reason declined. The purpose of this post is to sketch the argument and see if people commenting see anything wrong with it.

My model is a very simple one. The whole atmospheric system is one object with uniform temperature, the sea  another object with uniform temperature. The atmosphere gains heat via net radiation input from the sun, loses it via conduction to the sea. At any instant the temperature of the atmosphere is atmospheric heat/atmospheric heat capacity, and similarly for the sea.

If atmospheric temperature were constant for a sufficiently long time the two temperatures would approach equality, but atmospheric temperature has been rising due to net energy input from the sun. Heat loss to the sea by conduction is proportional to the temperature difference between atmosphere and sea. If the net input from the sun had been constant  for a sufficiently long time, the equilibrium of the system would be a constant temperature difference between atmosphere and sea. That gives a constant net heat increase for the atmosphere (radiation in, conduction out) and for the sea (conduction in). Atmosphere and sea are warming at the same rate because if atmosphere warmed faster the temperature difference would be increasing which would increase heat flow from atmosphere to sea which would decrease the rate of warming of the atmosphere, increase that of the sea, until the two equalized. I am ignoring the fact that as the whole system warmed it would radiate more out to space. For simplicity I assume that that effect is small over the range of temperatures I will be looking at, so we can assume constant net radiative input. I am ignoring the fact that if the process went on long enough the sea would boil. I'm looking at much shorter time period than that—decades not millenia.

Now assume that something changes, reducing net radiative input just enough so that heat coming into the atmosphere via radiation is just equal to heat leaving the atmosphere via conduction. The atmosphere stops warming. But it's still warmer than the sea—that's why it is losing heat via conduction. And since it is still losing heat by conduction, the sea continues to warm. Gradually that warming reduces the temperature difference, reducing the rate of heat transfer from atmosphere to sea, slowing the rate at which the sea is warming. If net radiative input remains constant, atmospheric temperatures will gradually start to go up again. If, on the other hand, net radiative input from the sun declines at the same rate at which heat transfer by conduction is declining, atmospheric temperature will remain constant, sea temperature will continue to rise but at a declining rate. 

Figure 1 is a graph of atmospheric temperature taken from skepticalscience, a pro-warming site (i.e. one that argues that AGW exists and is a very serious problem that needs to be dealt with):
Figure 1

eyeballing it, temperatures appear to flatten out sometime between 1998 and 2002 and remain roughly constant thereafter.

Figure 2 is the same graph of ocean heat that I discussed in a previous post.

Figure 2

Eyeballing it, the rate of warming appears to decline about 2003.

This is a very simple model and a very simple description of the graphs. Since both graphs have a lot of noise, a simple description may be the best we can do. As should be obvious, my point is only qualitative. I have not made any calculation of how large the heat flow should be from atmosphere to sea as a function of temperature difference and I have not offered data on the actual size of the temperature difference over time. 

All of that would require a much more elaborate analysis. My point is only that the observed pattern of atmospheric temperature going flat followed by ocean warming slowing but not stopping is the pattern one would expect if net radiative input dropped. It is thus consistent with the idea of a pause in warming, not in the sense of temperature increase of the whole system going to zero—the sea is still warming—but of the temperature increase of the system slowing in the way to be expected if atmospheric warming stopped.

Two questions for commenters:

1. Have I made any mistake in my analysis of the simple model? The only problem I see is that the drop in rate of warming on Figure 2 looks too abrupt—on my model it ought to be a gradual change. But it's a noisy graph.

2. Are there obvious ways in which making the model more realistic would change the conclusion? In particular, are there obvious improvements which would justify the claim, discussed in my earlier post, that there is no pause because the "missing heat" is going into the ocean? I take that as meaning that what has changed is not the net radiative input from the sun but the conductive loss to the sea, that the flattening of atmospheric temperature is due to an increase in the latter not a decrease in the former.


P.S. A couple of people commenting on this (one on G+) argue that I have the heat flow backwards, that the input from the sun mostly goes to the land and sea and is then transferred up to the atmosphere rather than going in the other direction as in my model. I have not yet figured out the implications for making sense of the data, assuming they are correct.

Sunday, February 23, 2014

Pseudoscience the Left Likes

Not only the left. And, oddly enough, a firm run by a libertarian.

I don't usually link to other people's posts, but this one is worth reading. It fits, in an odd way, with my old post about who really does or doesn't believe in evolution.

Everyone is in favor of science—except when he isn't.

Deficit Data Confusion at

Someone posted to Google+ a bar graph showing a rapid decrease in the deficit over Obama's period in office. Searching for information to check it, I located a  page on with lots of budget information, including information on the deficit, and found the contents of the two to be strikingly inconsistent.

Here is the bar graph:

And here is the spreadsheet:

The first four numbers for the deficit on the bar graph are slightly lower than the corresponding numbers on the spreadsheet. The final number is much lower. According to the spreadsheet, the 2013 figure is about 60% of the 2009 figure, not less than half.

My initial guess was that the bar chart was a fake produced by Obama supporters outside the government, but a little searching located it on a different page on, dated October 30, 2013. The U.S. fiscal year ends on 30th September, so the graph ought to be showing real data. The spreadsheet does not, so far as I can tell, say when it was calculated, and it gives the 2013 deficit as an estimate, which suggests that it may be presenting earlier figures from a point at which it looked as though the deficit was going to be larger than it ended up being. But that does not explain the smaller discrepencies for the previous four years.

Anyone know what's going on?

Here is a similar and at least roughly consistent bar graph from another source. It goes one year farther back, making the overall picture look rather different.

Saturday, February 22, 2014

Partisanship, Global Warming and Immigration

I have been involved in a number of recent online threads on global warming. An interesting and depressing pattern is the way in which the arguments are dominated, on both sides, by partisanship.

One example is the way in which, if anyone posts anything critical of the conclusion that we ought to be taking strong action to slow warming, he is promptly labeled a "denier" and accused of denying that warming is happening. Those responding are lumping everyone who disagrees with them together, assuming that any argument made by anyone on the other side must be supported by everyone on the other side.

A second example is the way in which threads on climate tend to morph into disagreements on other and unrelated issues, with each side seeing the other not in terms of their view on the subject being argued about but as part of a broader enemy—very roughly speaking, "left" vs "right." In at least one case, people on both sides turned it into atheism vs Christianity, in others liberal vs conservative.

None of this is surprising, only depressing. Humans seem to have a strong, probably hard wired, tendency to see the world in terms of us and them, ingroup and outgroup.

For a still more striking example, consider arguments about immigration. One common argument for restricting it, usually coming from people who think of themselves as egalitarians, is that a flood of poor immigrants would depress the wages of the present poor. That conclusion may or may not be correct. But if it is, that means that people who think they are in favor of equality are willing to block an enormous improvement in welfare for people who currently live on  less than a dollar a day—the foreign poor who would come—in order to avoid a smaller decrease in the welfare of people who currently make about eight dollars an hour.  That is explainable only on the grounds that the foreign poor, being members of the national outgroup, don't really count in moral calculations.

The Claim that the "Missing Heat" is Going into the Oceans

One claim I have repeatedly seen in online arguments about global warming is that it has not really paused because the "missing heat" has gone into the ocean. Before asking whether that claim is true, it is worth first asking how anyone could know it is true. A simple calculation suggests that the answer is one couldn't. As follows ... .

Part of the claim which I assume is true is that from 90% to 95% of global heat goes into the ocean. That implies that the heat capacity of the ocean is 10 to 20 times that of the rest of the system. If so, and if the pause in surface and atmosphere temperatures was due to heat for some reason going into the ocean instead, that should have warmed the ocean by 1/10 to 1/20th of the amount by which the rest of the system didn't warm.

The global temperature trend in the IPCC projections is about .03°C/year. If surface and atmospheric temperature has been flat for 17 years, that would put it about .5° below trend. If the explanation is the heat going into the ocean, the average temperature of the ocean should have risen above its trend by between .025° and .05°.

Would anyone like to claim that we have data on average  ocean temperature accurate enough to show a change that small? If not, then the claim is at this point not an observed fact, which is how it is routinely reported, but a conjecture, a way of explaining away the failure of past models to correctly predict current data.

The next question is what has actually happened to heat content. The data are shown at

The page insists on showing you a series of different graphs, so I am pasting in a screenshot of the first one. The second shows heat content down to 2000 meters; you are welcome to look at that and see if you agree with me that it shows the same pattern, if a little less clearly.

Examining the graph, in particular the black line showing the yearly average, it looks as though the rate of increase from about 2003 on is slower, not faster, than over the previous decade. The change is not as striking as the corresponding change in the graphs of surface or atmospheric temperature and seems to start a little later, but it is just the opposite of what we would expect if the slower warming elsewhere was being balanced by faster warming of the ocean. And, since the ocean is being heated from above, one would expect the pattern of ocean temperature to lag the pattern of atmospheric temperature.

Anyone interested in disputing either half of this post and defending the claim that there has not really been a slowdown in global warming because the missing heat went into the ocean? I am not looking for links to articles claiming that it's true—too much of the online argument on climate consists of dueling appeals to authority. I'm looking for actual arguments.

Monday, February 17, 2014

Report on a Successful Breeding Program

My mother claimed to have once taught my father a song well enough so that he could tell if something was that song or wasn't. He denied it.

My father married a musical wife. I married two musical wives in succession. The child of my first marriage married a musical wife.We have now spent three generations breeding musical ability back into his descendants. This post is to report on the success of the project.

And here is the evidence, produced a few days ago by my grandchildren.

Monday, February 03, 2014

A New Dining Custom

A couple of days ago I joined Robin Hanson, briefly in town, and about twenty of his other friends for dinner at a restaurant. We were seated at a long table, with the result that my conversation was limited to those at my end of it. That struck me as a pity, since Robin tends to have interesting friends.

I proposed a solution and Robin's wife proceeded to implement it. Every five minutes, everybody shifts one seat to his right.  The displacement is small enough so that no conversations are immediately interrupted, but, as those you were talking with move gradually farther away, you can taper off one conversation and start another with those now coming into range. In the course of less than an hour you have an opportunity to meet and converse with everyone.

Worthless Journalism

This morning I came across a news story purporting to show that vaccination against the HPV virus does not make girls more likely to be sexually active. After reading it, I have no more reason to believe the conclusion than before reading it, making it a good example of bad journalism.

The article describes an experiment in which more than 300 girls between 13 and 21 were interviewed about their sexual behavior before getting the shot and at intervals thereafter. Before getting the shot 42% of the girls said they were sexually inexperienced. Six months after, of the 99 who had been inexperienced, 20 no longer were. That is the sum total of information about whether the vaccination makes girls more likely to be active provided by the article—there is also a little more information, almost equally worthless, about the effect on the behavior of those already active. 

So far as I can tell from the article, there was no control group. The article offers no information about how many girls from a group with the age distribution of those studied would be expected, absent the vaccination, to become sexually active over a period of six months. The only thing it tells us relevant to what it is supposed to be about is that the researchers say that their research produced the conclusion that, pretty obviously from the tone of the article, they wanted it to. No information by which a reader can decide for himself whether it's true.

Just for fun, I tried doing a back of the envelope calculation to see how plausible their claim was. To get an upper bound on the rate at which girls become active, assume that 100% go from inexperienced to experienced between age 13 and 21, making the average rate 11%/year. The story does not give the age distribution of the group studied, but if we assume an equal number of each age and take the group size to be 300, they should have been going from inexperienced to experienced at a rate of about 33/year. According to the article, the rate was actually 20 in six months. Insofar as the calculation tells us anything, it suggests that the rate for those vaccinated was higher than would have been expected—the opposite of the conclusion of the article and, presumably, the study.

That is not very strong evidence that the study's results were bogus, since we do not know the actual age distribution. It could have been concentrated in an age range where the average rate was as high as the rate observed. I have not read the study itself, so have no way of knowing whether it produced evidence for (or against) its conclusion. But the article on it is pure puffery.

The article mentioned, at the end, a previous study on a smaller scale that did use a control group. There too, it gave no information by which the reader could tell whether the reported conclusion was true. "That study ... found no significant differences" presumably means that the any differences found were not statistically significant, which sounds as though it means that there were no differences that matter—provided the reader does not know what "statistically significant" means.


P.S. A commenter (via Google+) provides me a link to the study. What the authors were looking at was not the relation between vaccination and sexual behavior but the effect of vaccination on perceived risk of sexually transmitted infections and the relation between that perception and sexual behavior. The authors report that for a majority of participants vaccination did not affect perception; they do not say what the effect was on the minority. They found no evidence that a reduction in perceived risk resulted in an increase in sexual activity. Their study produced no information on whether vaccination affected sexual behavior through mechanisms other than its effect on reported perception of risk—for example by implying that it was normal and accepted for girls to be sexually active.

The oddest thing in the paper is the theory they seem to be testing, which they refer to as risk homeostasis. That theory apparently holds that individuals act to maintain a constant level of risk. In the sexual context, that would imply that any reduction in the riskiness of intercourse would be exactly balanced by an increase in frequency.

From the economist's point of view, that is equivalent to assuming that the total amount a consumer spends on a good is independent of its price, that if the price falls in half the consumer doubles his consumption. It makes me wonder if risk homeostasis is the result of someone reading a comment by an economist and not understanding it.