On Consensus

Guest post by Daniel Bailey

As individuals, we learn through hard experience in our lives how to make choices.  Over time we learn to make optimal choices, that is, choices based on as much evidence as possible that will then lead to the best possible result.  That is essentially the scientific method in action.  In science, when evaluating all the available evidence, the theory that best explains what the data shows is usually the best choice.

A small number of people meeting to make a choice usually do so by discussing the various points that matter most to each, usually leading to a quick resolution and decision.

When a large number of people come together to make a decision about something, however, chaos can ensue.  There exists not equal abilities to both communicate and to share the time available to communicate, resulting in an impasse.  To resolve this, people typically appoint a knowledgeable person they trust to make an optimal decision on their behalf.  These appointed people form a committee, a smaller number of informed individuals empowered to make decisions for the good of the whole.

In committees, choices are made by the input of the group of people comprising the committee.  This group-made set of choices is said to be the consensus of the group.  The group consensus is then relayed back to the rest of the people, either by the individual members of the committee or by an appointed representative of the committee.  The people then have a choice:  to accept the consensus developed by the person they entrusted to make it, or not.

This arrangement has worked quite well for most bodies of people in the world throughout history.

But when it comes to communicating the consensus of climate science, it does not.  Consensus delivered to the public from scientific organizations worldwide on climate change is met with derision, vitriol and dismissal.  

Let us consider an example of that.  

Submitted for your approval:  The Teacher and the Student.



Teacher:  It has become apparent that a disconnect exists between the understood level of agreement, or the Scientific Consensus, on climate change within the scientific community and that of the rest of humanity. 

Student:  (thinks, vaguely remembers reading “Scientific Consensus” last night between many beers, smiles at memories of beers, nods) OK.

Teacher:  The current level of Scientific Consensus on climate change was expressed most recently by the National Academy of Science in their publication Advancing the Science of Climate Change.  In it they specify: 

A strong, credible body of scientific evidence shows that climate change is occurring, is caused largely by human activities, and poses significant risks for a broad range of human and natural systems….
Some scientific conclusions or theories have been so thoroughly examined and tested, and supported by so many independent observations and results, that their likelihood of subsequently being found to be wrong is vanishingly small.

Such conclusions and theories are then regarded as settled facts.

This is the case for the conclusions that the Earth system is warming and that much of this warming is very likely due to human activities.

Student:  Huh?

Teacher:  (translates to student-speak) Rock-solid.

Student:  Oh.  So what does “very likely” mean, then?

Teacher:  “Very likely” means a greater than 90% likelihood of probability.  I.e., pretty certain.

Student:  Lemme see if I got this right:  the Earth is warming = rock solid.  That we are the ones causing it is pretty certain.

Teacher:  Yes.

Student:  So what’s all the fuss about, then?

Teacher:  People don’t want to believe, for various reasons, so they desperately look around for anything they can to perhaps put off having to face reality.

Student:  So people are in denial?

Teacher:  That’s a strong word.  We usually use the word “Skeptic” and reserve “Denial” for those beyond rehabilitation.  Usually they’re the ones without a strong background in Critical Thinking or the Scientific Method.  An additional problem for them is that, in order to find something concrete to overturn the human-causation of global warming, they would have to come up with a physics-based theory that explains why the greenhouse gas effect of CO2 only works part of the time and not others.   A deeper problem exists for those Skeptics who have enough knowledge of the science to be dangerous, but not enough awareness of self to realize the limits of their knowledge.

Student:  Explain further this semi-mythical “greenhouse gas effect of CO2”, oh Fount of Knowledge.

Teacher:  Snark won’t score you extra credit, boy.  Based on the radiative physics of greenhouse gases, here’s what we know:

1.  Increasing the level of a greenhouse gas in a planet’s atmosphere, all else being equal, will raise that planet’s surface temperature.

2.  CO2 is a greenhouse gas.

3.  CO2 is rising.

4.  Therefore (given 1-3 above) the Earth should be warming.

5.  From multiple converging lines of evidence, we know the Earth is warming.

6.  The warming is moving in close correlation with the carbon dioxide.

7.  The new CO2 (as shown by its isotopic signature) is mainly from burning fossil fuels.

8.  Therefore the global warming currently occurring is anthropogenic (caused by mankind).

Student:  That’s a lotta links.  So, in order to disprove human-caused global warming, deniars skeptics would have to find a viable physics-based alternative to one of the points in that chain you just outlined?

Teacher:  Correct.  And to date, none have been able to do so.  Plenty have espoused alternative theories on blogs, but none have been able to survive scrutiny in a peer-reviewed publication.  At this point, the chances of viable alternatives arising are remote.

Student:  So why hasn’t the general public caught on?

Teacher:  Excellent question, my young apprentice!  It’s due to some skeptics and media types using a slightly different view of consensus, popularized by Funtowicz and Ravetz in 1990: 

1. No opinion with no peer acceptance;
2. An embryonic field attracting low acceptance by peers;
3. Competing schools of thought, with medium peer acceptance;
4. A dominant school of thought accepted by all but rebels;
5. An established (many validation tests, causal mechanisms understood) theory accepted by all but cranks.

The skeptics and media types paint a picture of climate science as being in the 2 or 3 range on that scale.  However, take into consideration the NAS report Advancing the Science of Climate Change discussed previously, and these other statements from leading academic bodies and governments around the world:

Consensus Statements at Logical Science

Consensus Statement at the Union of Concerned Scientists

The Signed Consensus Statement on Climate Change by 18 Associations

Signed Consensus Statement on Climate Change by 11 International Science Academies

By these measures, on the Funtowicz and Ravetz scale, the consensus on climate science would come in between 4.5 and 5, with the only remaining discussion revolving around why it shouldn’t be a full 5, given the overwhelming mass of converging evidence extent today.

Student:  Your Immenseness is truly in rare form today!

Teacher:  (smiling to himself, envisioning the poor grade forthcoming) Like the public, you have no idea.

This, then is where science stands:  consensus on climate change exists and has been delivered.  And been met with apathy, denial, anger, fear, ridicule and accusations of corruption.

So where do we go from here?

What is our path forward?

Let your opinions be known, as the committee on this issue now includes all mankind. 

For all are affected and at risk.

Posted by Daniel Bailey on Monday, 2 August, 2010

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