Tag Archives: Consensus

Define “AGW”

Spread over the Cook et al 2018 paper are the terms “anthropogenic climate change” and “anthropogenic global warming”. It is also mentioned a in table S2 of the supplementary material. I assume that “anthropogenic global warming” means that global temperatures are rising and humans have an impact. This seems to be supported by the consensus claim from the paper (my emphasis):

There is an overwhelming scientific consensus that humans are causing global warming (Cook et al 2016), with a number of studies converging on 97% agreement among publishing climate scientists or relevant climate papers (Doran and Zimmerman 2009, Anderegg et al 2010, Cook et al 2013, Carlton et al 2015).

That is a far cry from the previous statement in the Alice in Wonderland paper. In that paper, the claim was made that there is a consensus that global warming “presents a global problem”. A claim that obviously was unsupported by the papers that were referenced.

At least he skipped the “dangerous” part of the claim. It is now in line with what the referenced papers researched. As explained in the link above, the referenced papers investigated the claim that global temperatures are rising and that humans have an influence in this. Not whether it is dangerous. Not whether something should be done about it.

However, I don’t think that the term “AGW” is used in this way in the paper. This sentence in the abstract makes me think that he means something different (my emphasis):

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“Climate Risks” as conclusive as the link between Smoking and Lung cancer?

Via the Cliscep post “Don’t call me an alarmist,” says alarmist, I landed on this livescience article: Treading the Fine Line Between Climate Talk and Alarmism. It is an op-ed written by Sarah E. Myhre about climate change communication and her wish not being called an alarmist.

One thing that caught my attention in the op-ed was this statement:

We would never fault an oncologist for informing patients about the cancer risks that come with smoking. Why would we expect Earth scientists to be any different, when we’re just as certain?

It is not clear from the text what we should expect from those Earth scientists. Luckily, the links goes to an article in Scientific American, titled “Climate Risks as Conclusive as Link between Smoking and Lung Cancer”. So apparently, she means that the Earth scientists know as much from climate risks as medical scientists about the link between smoking and lung cancer…

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Sugar versus fat: why so many scientists got it so wrong for so long

Looking for more background when I was writing previous post, I came across a very lengthy, but nevertheless interesting story in The Guardian. This long read is titled The sugar conspiracy and the subject is the battle between the theory that sugar is the (main) reason for the obesity epidemic and the established theory that fat was the culprit.

This is not something recent, the controversy originated already in the middle of last century and, although the fats theory was found to be ultimately wrong, the sugar theory was ridiculed, discredited and careers were ruined. It took fifty years for the theory to resurface, leaving the question why the top nutrition scientists got is so wrong for so long.

We hear that objection often in climate change discussions: so many scientists can’t be wrong for so long. Well, it is possible and the sugar theory is only one of its manifestations.

The most interesting part of the Guardian story is the tension between the scientist who first proposed this theory (John Yudkin) and his scientific adversary (Ancel Keys). It reads like the current controversy on climate change. Replace Yudkin with your favorite skeptic, Keys with your favorite alarmist, fats with CO2, meat/dairy/sugar industry with Big Oil/Tobacco and the story sounds really modern. There are a lot of similarities between how the scientists in the two sciences treat those who are skeptical towards the consensus position.

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The lessons we learn from nutritional science

My employer is concerned about the health of his employees and subscribed us all to a health newsletter. Every two weeks we receive some health tips in about ten to fifteen lines, based on the latest findings in health science. In the last newsletter, there was one article that jumped out on me. It was titled “Lots of fats or lots of carbohydrates?”. This is how it starts: (translated from Dutch)

Nutritional Sciences made large blunders in the past. For a long time, we had to avoid fats to stay healthy. Not only was this the wrong advice, it also has proved counterproductive.

In the 1950s, scientists drew the wrong conclusions from population studies. They focused on fats as the only cause of obesity and heart disease. Recent studies provide a more nuanced picture: a diet rich in fats and low in carbohydrates works at least as well to lose weight!

This sounded very familiar. Until a few years ago, fats were seen as something bad for our health due to our sedentary life styles and considered to be THE cause of obesity with loads of negative side effects like hypertension and heart disease.

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No conspiracy theories necessary

In the US Senate Committee on Commerce, Science and Transportation the emphasis was on the consensus: there are so many scientists and organizations that agree, so why would these few deni… euh, skeptics be right and the rest of the world wrong? Last post described already two reasons why I think this is a meaningless argument anyway. The third reason is that a consensus can have it wrong and that is not that unusual. There have been many examples before where everyone agreed and in the end everyone was wrong.

There are of course the most known examples like Galileo (against the theological consensus that the Earth was the center of the Universe), Albert Einstein (against the consensus against the theory of relativity), Harlan Bretz (against the consensus geological changes were always gradual and slow), Alfred Wegerer (against the consensus that continents were unmovable), Barry Marshall and Robin Warren (against the consensus that stomach ulcers were caused by for example stress or spicy foods) and probably many others who are less known or didn’t get into the history books. They all struggled against the consensus of their time and their assertions, although correct, were rejected. There is however a consensus that very recently collapsed and even has more similarities with the global warming/climate change story.

Since the 1980s there was a consensus about the link between fat intake and coronary artery disease. Reduce one and the other will also reduce. Guidelines were issued and low-fat diets were seen as a means of combating obesity and heart disease. This gave rise to a whole industry producing low-fat products that were assumed “healthy” in the of face the guideline. This consensus was challenged by a minority group, that gradually became larger.

In the beginning of 2015 a study was published in the Annals of Internal Medicine in which researchers pooled 72 studies and clinical trials and found that total saturated fatty acid was not linked to coronary disease risk or that a lower intake of fats is beneficial for the heart.

This does of course not mean that a high fat intake would be entirely harmless, but it’s not the major culprit that the experts led us to believe until last year. There are even those who suspect that the directive to eat less fat even had harmful effects. Healthy high-fat products, such as nuts, olive oil and fish oil, were given a bad image and dietitians lost sight of the risks of a higher sugar intake (more sugars were added to low-fat products to compensate for the loss of flavor brought by the fats).

Now that is something very interesting. Here is a consensus that held from the 1980s until now, pinpointing one factor (even lacking evidence) and that the media, the public as well as the professionals bought firmly into it. Yet no conspiracy and no large-scale misinformation campaigns were needed. There was no group of people who wanted to fool anyone, nor was there any intentional deceit. This information was put out in good faith and although it was unjustified by the science, the consensus survived until last year.

There are several similarities with climate science. Both sciences study a complex, coupled system (human body and the climate system). There is however a difference in experience (thousand versus decades).

Both sciences also have their limitation in studying their subject (there are ethical objections to put people in standardized experiments versus there only be one patient and in fact it is not sure whether it is a patient or not, because of scarce reliable historical data).

This means that there is a huge uncertainty regarding the outcome of dietary studies. People are complex organisms and live in a complex interaction with their environment. There are thousands of variables and they all can influence each other. There are things like age, physical health, fitness, genetic predestination, food preferences/availability, personal habits, background and so on. dietary fat is only one of those.
The same in climate science. There are also thousands of variables and they can all influence each other. The sun, clouds, the ocean circulations, water vapor and other greenhouse gases, the biosphere, carbon cycle, and so on. CO2 is only one of those.

In such observational studies, it is not possible to pinpoint one variable as THE cause. There is no way to know whether the real cause(s) were among the tested variables.

The current medical researchers didn’t point to just another factor to replace one cause of coronary disease with another, they just showed that the consensus was not based on good scientific evidence. The dietary guideline was not put in place because the data said there was a link between dietary fats and coronary diseases, but for other considerations.

What are the chances that in 30-40 years we will be told that the current guidelines to limit CO2 emissions lacked any solid evidence and that our focus on this mirage even had harmful effects 😉

To me this example shows again that a consensus can be wrong and that is not unusual. It doesn’t mean we must dismiss every consensus, but we clearly can’t rely on it without verification. We have to keep a healthy dose of skepticism, especially in a science dealing with loads of uncertainty like dietary studies or climate studies. It is this skepticism what I think is missing in climate related issues.

The science, the evidence and the (satellite) data

Recently I viewed the video Sen. Cruz Questioning Sierra Club President Aaron Mair on Climate Change in the Judiciary Subcommittee on “Over-regulation and its impact on minority communities”. The video was from a couple weeks ago and went viral at that time. It became perfectly clear why when I at last viewed it. Skeptics got used to be viewed as the underdog and blamed for not having the evidence on their side, but in this video we saw Mr. Mair initially claiming to be driven by the science, the evidence and the data, yet when the questioning advanced, it became quickly clear that he wasn’t driven by the science, nor by the evidence, nor by the data. He probably wouldn’t even notice the science, even if it bit him. 😉

This is how the story goes. In his written testimony, the president of the Sierra Club wrote that the science behind climate change and its effect on minority communities should not be up for debate, which provoked a sequence of questions from Senator Cruz, which the president of the Sierra Club had a hard time answering. Just watch the video if you didn’t already.

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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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