Scientific Consensus = ??

Science is the religion of our time, and like all religions it can be used in a more or less constructive way. The role of scientists is to use the scientific method to gain knowledge that at best is useful for people on our planet. 

In the debate on global warming, Al Gore and many with him, argue that there is a scientific consensus on the causes of global warming.  But what do we mean by scientific consensus? Wikipedia, the incarnation of consensus, states:

• Scientific consensus is the collective judgement, position, and opinion of the community of scientists in a particular field of study. Consensus implies general agreement, though not necessarily unanimity. Scientific consensus is not by itself a scientific argument, and it is not part of the scientific method. Nevertheless, consensus may be based on both scientific arguments and the scientific method.
• In public policy debates, the assertion that there exists a consensus of scientists in a particular field is often used as an argument for the validity of a theory and as support for a course of action.
  

This captures pretty well a consensus about scientific consensus: It is not by itself a

scientific argument or part of the scientific method, but can nevertheless be used to support action.

A poll showing that a 75% of general audience believes the human activity can influence the global climate, would then give support to scientific consensus on the causes of global warming. 

But since scientific consensus may be more politics than science, it can lead to wrong actions. So how is then scientific consensus about global warming formed? In the Wikipedia article Scientific opinion on climate change we read:

• National and international science academies and professional societies have assessed the current scientific opinion on global warming...attributable to human activities...endorsed by the Intergovernmental Panel on Climate Change (IPCC).

The many international science academies and professional societies backing the consensus, all base their opinions on IPCC.  Now IPCC itself motivates its assessment from a couple computer simulations showing a better fit with certain data with a certain forcing, than without forcing.

In previous blogs I have tried myself to assess the accuracy of these computer simulations, and found more questions than answers. The mere fact that forcing changes the output is not surprising, since this is built into the code. The mere fact that you get a headache by bumping your head into a wall, does not prove that if you have a headache, then it is caused by bumping your head into a wall. It may be caused by drinking too much wine or...

We thus find scientific consensus on global warming ultimately resting on one single set of computer simulations. But a top-down pyramid is very unstable and a different set of computer simulations will motivate a different scientific consensus. The consensus itself has no scientific value.  It is like political opinion, which can shift from one day to the next. In fact, there is no scientific consensus on causes of global warming not even today, as shown in Climate Debate Daily.

Again we come to the conclusion that what is needed is more reliable computer simulations, not more scientific consensus based on unreliable simulations.

Another example of scientific consensus is given in my blogs on d'Alembert's paradox

and Interview with Editors of Journal of Fluid Mechanics showing the fluid mechanics community scientific consensus expressed by Wikipedia and the Editor of JFM: First, there is no paradox. Second, if after all maybe there is a small paradox, it can somehow be resolved by hinting at the viscosity of a viscous fluid. 

The scientific consensus is thus that a basic problem of fluid mechanics, is not a basic problem of fluid mechanics, but this is in contradiction to the scientific method and thus corrupts the science of fluid mechanics. If the science of global climate is equally corrupt, the we may be in trouble...for more trouble see Giant Particle Collider Struggles.

In the motivation for the 2007 Nobel Peace Price awarded to Al Gore and IPCC we read:

• Through the scientific reports it has issued over the past two decades, the IPCC has created an ever-broader informed consensus about the connection between human activities and global warming. Thousands of scientists and officials from over one hundred countries have collaborated to achieve greater certainty as to the scale of the warming. Whereas in the 1980s global warming seemed to be merely an interesting hypothesis, the 1990s produced firmer evidence in its support. In the last few years, the connections have become even clearer and the consequences still more apparent.

Ever-broader consensus, thousands of officials collaborated, firmer evidence, greater certainty, even clearer, still more apparent...