How meaningful is the consensus on global warming?

Since almost a month now I am picking on the “scientific consensus” on global warming, more specific the consensus found in the Cook Survey. Now you could ask: “Isn’t it the reality that there is a consensus between scientists?”.

It could surprise you, but I think that, indeed, most people believe in man-made global warming and I see no reason why it would be different for scientists.

“But” would you say, “Then why the picking on all those studies that actually find a consensus?”. The answer is simple and is in fact another question: what exactly is there a consensus about and how meaningful would that be?

The methodology of the papers written about the consensus learned us some very interesting things about it. The Doran/Zimmerman paper learned us that the number of scientists considered the best measure for the consensus is incredibly small, even within the Earth sciences. Doran/Zimmerman even had to toss out 97.5% of the answers they received to come to the desired conclusion.

The Anderegg et al paper learned us that within this small group of climate researchers, the “convinced” publish more then the “unconvinced”. Which is not really a big surprise considering that taking the skeptical position is not exactly desirable.

The Cook paper learned us that most of the consensus position comes from scientists who just take global warming for granted. Not because it was their field of expertise, but for other reasons not investigated in their study. It also learned us that there were other reasons than scientific to write this paper.

But not only the methodology learns us more about the consensus. Just looking at what is investigated unravels more things.

How meaningful is a consensus if there is no conclusive evidence and in stead an opinion has to be surveyed to make it clear? In the Cook study we heard about the Consensus Gap. Basically something like our scientists know everything there is to know about the issue, now it is time for the public to accept that and support climate policies. It is portrayed as an academic issue: the scientists know, but the public is still in the dark. In reality there are many (undisclosed) uncertainties. Just look at the field of study: climate science is studying a chaotic and complex system over a longer period (yet there is only reliable data available since a couple decades and some properties even less). Claiming a consensus in a highly complex system with sparse data seems rather artificially. It definitely doesn’t make much sense to compare it with sciences that study much smaller and more well defined systems. However, the comparison is made and gives an appearance of confidence to the public.

How meaningful is a consensus in a polarized debate where adhering to the skeptical side can have severe consequences? In such an environment being skeptical could be a bad career move and the appreciation from peers/the public could also be on the line. Sure, that most of the papers support the consensus can be that the scientists agreeing on the science, but in a situation where it is not a good idea to be a skeptic it is not surprising either that most papers are supporting the consensus. How to tell the difference when this aspect was not investigated?

How meaningful is a consensus when the queried statement is so broad that it could be accepted by believers and skeptics alike? Sure, CO2 is a greenhouse gas and when humans increase its concentration, it will have an effect on temperature. But that is a very broad definition. In practice this can go from “global warming is real, but not harmful, maybe even beneficiary” on the one side to “global warming is real and a threat” on the other. When we want to consider whether we need action on global warming, such a broad range is meaningless and calling that the proof why the public needs to support action is misleading.

To conclude, I have no problem accepting that most scientists believe that global warming is real and man-made, but not necessarily for the reason that is suggested in those papers.

Just my two cents.


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