Dr Judith Curry and Climate Science’s Uncertainty Monster

The presentation was a keynote talk at the “2nd International Workshop on Econometric Applications in Climatology.” Linked in the post are the slides in her presentation, which are very useful in understanding the presentation. 

 

Curry’s effort attempts to articulate the difference, in her view, between what we know and what we do not know about climate science. Her views began after Climategate, and have changed over the past few years. 

 

Confusion and ambiguity are common in the public and the climate community, and occur because all too often members of the community fail to distinguish between knowledge and ignorance; objectivity and subjectivity; facts and values; prediction and speculation; and science and policy. 

 

In her view, the science as reported by the UN Intergovernmental Panel on Climate Change (IPCC) has institutionalized overconfidence. The overconfidence has resulted in disagreements based on: insufficient observational evidence; disagreement about the value of different classes of evidence (e.g. models); disagreement about the appropriate logical framework for linking and assessing the evidence; assessments of areas of ambiguity and ignorance; and belief polarization as a result of politicization of the science. 

 

To this list, SEPP would add that the IPCC and its parent organization, the UN Framework Convention on Climate Change (UNFCCC), have failed make it explicitly clear in every publication that their mission is not to understand all the influences on climate change, but purely the human one, thus ignoring major natural influences on climate change.

 

Curry goes on to describe what she calls the UNFCCC/ICCC ideology: 

1. Anthropogenic [human-caused] climate change is real 

2. Anthropogenic climate change is dangerous 

3. Action is needed to prevent dangerous climate change

4. Deniers are attacking climate science and scientists 

5. Deniers and fossil fuel industry are delaying UNFCCC CO2 stabilization policies

 

Curry discusses major issues regarding the treatment of uncertainty, including that the often used Bayesian statistical methods, which have difficulty in dealing with true uncertainty, are subjective, and may lead to biased results.

 

She suggests Bayesian methods may be appropriate for two-value logic: probability the hypothesis is true and probability the hypothesis is false. However, the climate problem requires evidence based logic with at least three values: 1) evidence for the hypothesis, 2) total ignorance (or uncommitted belief); and 3) evidence against the hypothesis. 

 

She concludes with the statements: “In the 5 years since I started stalking the uncertainty monster, we’ve seen a lot of intellectual progress on how to frame and approach this issue. It is becoming easier for scientists to do and publish research that challenges the consensus. 

 

That’s the good news. “The bad news is that the interface between climate science and policy remains badly broken. Many politicians seem to have become uncertainty deniers, with President Obama leading the pack. The UNFCCC/IPCC is on a collision course with reality; it will be interesting to see how the Paris meeting goes next Dec, and how the IPCC AR6 will proceed. But science seems less and less relevant to what is going on in the policy arena. 

 

Which is fine; please get out of our way and let us do our science so that we can try to figure all this out by exploring the knowledge frontiers, rather than pledging allegiance to the consensus.” In SEPP’s view, Curry’s assessments apply to the US National Assessment by the US Global Change Research Program as well as to the IPCC. See links under Challenging the Orthodoxy.