I wrote recently about the new report from the UN Intergovernmental Panel on Climate Change (IPCC), released as a “Summary for Policymakers” of “Global Warming of 1.5°C,” a deeply politicized document that makes the following central arguments:

• The world has only 12 years to prevent a climate catastrophe.
• The safe limit for anthropogenic warming through 2100 now is 1.5°C rather than the long-argued 2°C.
• The midpoint of the taxes on conventional energy required by 2030 to avoid severe climate impacts is $3,156 per ton of greenhouse gas (GHG) emissions, or more than $29 per gallon of gasoline. Those required taxes rise rapidly over the course of the century.
• Such sharp increases in the cost of conventional energy would have positive net impacts on almost all dimensions of 17 “sustainable development goals (SDGs),” such as “gender equality.”

I discussed all the reasons why this new report is not to be taken seriously, but I confess that I made a mistake in the last point: The IPCC report lists only 16, not 17, SDGs (see p. SPM-27 and the accompanying discussion).

How did I make that mistake? After all, Figure SPM.4 in the report clearly lists SDG 1, SDG 2, … through SDG 17. Upon closer inspection it turns out that there is a gap: After SDG 12, the figure then lists SDG 14; there is no SDG 13.

Why is that? The authors of the new IPCC report might argue that the 13th SDG — “climate action” — would be redundant or misplaced in a climate report. Sorry, that argument does not wash. The report purports to evaluate each of the SDGs in terms of the “trade-offs” (adverse effects) and “synergies” (favorable impacts) in “energy-supply,” “energy-demand,” and “land [use]” dimensions. Are we to believe that efforts to achieve the 1.5°C limitation goal would have no effects on those three parameters? The question answers itself; but merely consider the UN’s own words about SDG 13:

Affordable, scalable solutions are now available to enable countries to leapfrog to cleaner, more resilient economies. The pace of change is quickening as more people are turning to renewable energy and a range of other measures that will reduce emissions and increase adaptation efforts. Climate change, however, is a global challenge that does not respect national borders. It is an issue that requires solutions that need to be coordinated at the international level to help developing countries move toward a low-carbon economy.

So much for the redundancy argument. Another possibility is that the authors of the new report decided to cater to the superstitions of some of the policymakers relying on IPCC analytic work in support of their policy proposals, in a fashion similar to a hotel ostensibly without a 13th floor. Can it possibly be the case that the august IPCC has deemed it appropriate to make an allowance for that very same triskaidekaphobia, while telling the world that the old and venerable safety limit of 2°C of warming is appropriate no more? After all, the climate policy debate supposedly is all about “science”: The international climate industry must be empowered to force upon all of us policies limiting warming to 1.5°C.

Is that phobia possibility ridiculous? Perhaps, but it is far from obvious that it is more so than the other possibility noted above, to wit, that the “climate action” SDG is redundant or irrelevant in a climate report delving into the implications of the various SDGs for energy supply, energy demand, and land use.

Perhaps the UN Framework Convention on Climate Change, of which the IPCC is a part, does not feel a need to avoid the number 13 while the authors of the report do. And if the IPCC is willing to bend to such silliness, is it really too farfetched to hypothesize that the IPCC has found it necessary to accommodate other convictions deeply held by fervent climate believers but unsupported by the evidence?

The debate over anthropogenic climate change in reality is far more than merely one over science; it is fundamentally a policy debate as well, reflecting profound questions about risk assessment, the interpretation of data, known and unknown unknowns, wealth redistribution, time preferences, intergenerational transfers, self-government and the implications of government powers ever larger and more cartelized, and much, much more. Such issues are heavily philosophical and inherently incorporate value judgments and other considerations both crucial and normative, about which “science” has little to say. That is why climate science, even apart from the major controversies that persist, is the beginning rather than the dispositive end of the climate debate, and the possible willingness of the IPCC to accommodate superstitions is convincing evidence of that reality