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.