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?

If climate science was a hard science or a science with an experimental approach, I wouldn’t have any problems. But climate science, being an observational science, can only observe nature taking its course and this has its limitations on the conclusions that one can bring. Observational research can only suggest relationships between factors and the conclusions can even contradict experimental studies. A classic example are the studies to the prescription of estrogen to woman to counter chronic ills of aging. In an observational study it was found that women who were prescribed estrogen had less heart attacks, yet in follow up clinical studies it was found that estrogen was actually increasing the risk on heart attacks. There is always the risk that some variable that wasn’t observed is the real cause, therefor wrongly assuming that one of the measured variables is the cause.

The problem is that it takes experimental research to determine cause and effect. Experiments that can’t be created in climate science because we only have one Earth and therefor don’t have the luxury to create an experiment to pinpoint the exact cause of this temperature increase. Despite that, climate scientists declare in no uncertain terms that they do know unequivocally the cause of the increasing temperatures since the 1950s: CO 2 .

This is strange in many ways. Climate science is a rather young science and gathered surprisingly very little reliable data until now. For temperature (very important if one want to prove global warming), there are some 160 years of temperature measurements, increasingly sparse and less reliable when one goes back in time. Reliable data only since thirty years or so. Even worse when looking at for example ocean temperatures: some very sparse data in the past (like hauling buckets from ships that happened to pass by), only reliable data since about ten years. Knowing that the subject of study is a long term trends in a complex, coupled, chaotic system, a subject that spans many fields and together with limited data, a scientific consensus seems premature or even unreliable. If for example there would be climate cycles longer than the observed data, as history suggests, then this could shoot a big hole in the theory of anthropogenic CO 2 as the main cause of the warming.

So, how can they be so damn sure that this consensus is correct? There are many possible explanations, but a big red flag is that this consensus emerges from a political environment and is promoted in an ideologically, emotionally charged atmosphere. When one looks deeper in the papers that declare this consensus, one notices that the results depend heavily on the (mis)interpretation of the definitions and of clever selections of the data, therefor making those result rather meaningless. In my humble opinion, it would be wise to be very skeptical of a proposed scientific consensus in such a situation.

Yet, for some reason this is not even taken into consideration and only few are questioning whether this proposed strong consensus is actually warranted.