Tag Archives: Faulty Comparison

Small amounts of very active substances can have large effects, but this doesn’t prove that carbon dioxide is such a substance

Two things came together today. First was A Guide to Understanding Global Temperature Data by Roy Spencer, which I read a week or so ago. Second, I was pointed to an article in the Guardian in which a white paper written by the same Roy Spencer was being rebutted.

Initially, it was not clear which paper was referred to and, although there were also 13 questions involved, the rebutted items didn’t seem to be similar to the guide that I read earlier. So I was a bit confused. Did Spencer wrote another white paper in which he also used that 13-questions format, but with other arguments?

Becoming curious, I went back to the beginning of the article to look for the source, and surprisingly, when I clicked the link of the white paper, the Guide to Understanding Global Temperature Data popped up. Strange. The white paper that the Guardian was rebutting, seems to be the exact same paper that I read a week ago…

The author of the article, Dana Nuccitelli, claimed that the arguments in the guide were an example of a Gish Gallop and therefor too time-consuming to rebut. Therefor he pointed to the Climate Myth database that was compiled by Skeptical Science and in stead of rebutting the arguments in the white paper, he just linked to entries in that database.

So far, so good. Let’s start with how the first argument was rebutted:

1) ‘Carbon dioxide is a trace gas’ is rebutted as Myth #127.

That was odd. I didn’t recognize this being one of the arguments that Spencer used in his guide, yet here the answer on question 1 seems to be reduced to “Carbon dioxide is a trace gas” and was rebutted as such. Meaning as if was being said that CO2 couldn’t have important effects because it is a trace gas in the atmosphere.

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The Observational science that is mistaken for an Experimental science

In my weekly catching us with the news I came across this article: Why the environmental movement can let the GMO-dossier go. In it, an environmental activist writes about how he changed his mind over genetically modified organisms. Before, he campaigned against them, but after looking into the matter, he changed his mind.

That is all very praiseworthy of course, but it was the way he changed his mind that surprised me (Translated from Dutch):

I decided to do the same as environmental movement relating to global warming: look if a scientific consensus exists that is based on the most reliable scientific studies such as systematic reviews and meta-analyses published in leading peer reviewed top journals like Nature and Science.

When he found there was a consensus that there are no indications that GMOs are harmful, he changed his position. The rest of the text was about further exploring this consensus position.

This was strange to me, because he seemed to be an intelligent guy with several university degrees, yet when he wanted to investigate an issue, he based it solely on the consensus position…

I have been there also, so I realize that of course it is not entirely illogical. When a group of scientists (who have it as their job to study a certain issue and therefor are experts in their field) agree on something, then it is not difficult to see that other people (who didn’t study it that closely) have no reason to doubt such a consensus. Whether we believe a “scientific consensus” is meaningful or not. How could those who didn’t study the issue as closely as the experts, criticize this consensus?

It is not really unreasonable to agree that a consensus is the accepted view with our best current understanding and the best starting point when we try to grasp a new field of study. In a way, I still hold this view, still today. If I am told by the experts that the consensus is that earth circles around the sun or that gravity exists, as a non-expert I have no problem with that and the consensus would be a no-brainer. Legitimate authority matters.

So why would I think differently when it comes to climate science?

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That doctor’s analogy again

During a web search I came across this page: Climate Change Communication: Taking the Temperature (Part 11) with Dr. Katharine Hayhoe. It seems to be part of a series consisting of interviews with 12 different climate scientists about climate communication. The answer on the second question was really interesting, I recognized immediately the often used, but flawed, doctor analogy:

2. How do you view your role in communicating science?

I see the role of a climate scientist as similar, in some ways, to that of a physician. We might suspect something is wrong with our bodies; but until we go to the doctor, take the tests, and wait for the evidence, we don’t know what is going on for sure. In the same way, we might see something changing in our climate; but until scientists collect the observations, analyze the evidence, and draw conclusions, we don’t know for sure what is happening. As climate scientists, we are the “physicians of the planet.”

With that role comes responsibility: to tell people about what we find. Imagine if you went to the doctor and they found something wrong, but didn’t want to tell you about it – because they were afraid you might react badly to hearing the news, or it would be against your religion or your politics to receive treatment. That scenario may seem far-fetched to us. In the same way, though, I feel that as climate scientists we have a responsibility to tell people: what is happening, why it’s happening, and what the outcome of our choices as a society will be.

In a way I could understand that both doctors and climate scientists are studying complex systems. But even then there are differences that prevent the analogy to fly.

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Trust me, I am a doctor…


The consensus argument is about maintaining the perception of authority of climate science. Unsurprisingly, often the comparison is made between a climate scientist and a medical doctor as a symbol of this authority. It goes like this: “Do you go to a dentist when you have a heart condition?”. This to indicate that we should agree when scientists say that “climate change is real” and “human caused”.

For the record, I have no interest in going to a dentist with a heart condition or to a nutritionist for a surgery. They obviously have their own specialization and skills. But analogies are great as far as they go, but only go so far. Analogies can be a great tool for explaining something new or something difficult to grasp. But it goes only as far as the similarities go. It seemed a fun project to find out how far I could stretch the analogy.

There are of course similarities. The human body is a complex organism, just as climate is a complex system. Both contain different processes that also interact with each other. They both are the object of study by scientists.

But there are also important differences. Medical science is several centuries old (there were medical schools around the first millennium). It wasn’t like the medical science of today of course. Back then they probably healed with herbs, ointments and blood letting. Medical science came a long way since then. The human body is studied very detailed these days, even the human genome is known to the last sequence. Lots of diseases have been studied and for most of them a successful cure was found or can be controlled. This has been done over many centuries and many, many patients. Experience about diagnosing and curing diseases is very large.

The same can not be said of climate science. A lot is known about climate, but climate science is a relatively young science. There is only reliable data since 30 – 50 years or in some cases even since the last decade. Before that the data is really sparse and/or in a not standardized format. They were used to gather for example weather data in a specific place, not climate data globally. Climate is weather over a longer time frame. It probably takes about 60 years for one cycle. So there isn’t even reliable data for one measly cycle. And how much experience do we have in diagnosing the effects of current CO2 levels?

There seem to be a lot of disciplines involved in climate science that all study a different subset of climate. Which expert do you believe when it comes to climate? Do you believe a paleontologist, a mathematician, a chemist, an ecologist, an economist,…? What if a paleontologist is talking about the meteorology or an ecologist about the economy?

In medical science, patients can be studied by comparing with healthy individuals. This is not exactly true in climate science. We don’t have a spare planet exactly as ours to investigate the differences that will occur when we pump in or extract CO2 out of the atmosphere. We seem to have only one patient and we don’t really know if he is sick and if so, how sick and how to cure. The data being used to diagnose seem to be highly processed and adapted data (look at how the the GISS data set morphed over time, returning it unrecognizable in the end) or computer models (that try to model an intrinsic chaotic system).

But last but not least, I will only go to a cardiologist that I trust. I will not go to someone who is known for making wrong diagnoses time after time or exaggerate their diagnoses for whatever reason.

To me it is clear the doctor analogy doesn’t hold much water. The two obviously have similarities, but in the end are too different to really compare.

Let me just say that I will trust some scientists, not all. Just as I will trust some doctors, not all. Depending on their specific skills, how trustworthy/successful they were in the past, how they were willing to share their data, how well they predicted things,… Trust is not a given, it is something that is earned. Whether one is a doctor or a climate scientist, both alike.