Mapmakers and navigators, facts and values

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Science  04 Jul 2014:
Vol. 345, Issue 6192, pp. 37-38
DOI: 10.1126/science.1255998

Discussion around the SPM approval process has been ill-framed, raising questions of scientific credibility. Although changes were made during the government approval process, author involvement preserved consistency with the science in the underlying report. Even if scientists desired more far-reaching consensus in some areas, the government-approved SPM remains scientifically credible. The underlying report and Technical Summary were unaffected by changes made during SPM approval. The report provides a “living map,” drawn in a social learning process between scientists (mapmakers) and policy-makers (navigators), to be used to traverse the largely unknown territory of climate policy.

The SPM successfully provides a comprehensive, policy-relevant assessment of mitigation pathways to alternative climate goals in terms of underlying technological, economic, and institutional requirements. This was the key expectation for the WGIII report. But the approval process also revealed limitations of the IPCC in processing scientific knowledge with immediate relevance for negotiations, in particular, ex post assessment of progress made to date in climate change mitigation efforts.

Government concerns over the grouping of countries arose despite major efforts to provide a balanced assessment: The SPM section on emission trends and drivers that entered the approval plenary offered more analytical perspectives than any prior WGIII assessment. As is common scientific practice, countries were grouped in different ways depending on the question assessed. The SPM focused on why emissions have been growing as countries develop and how these patterns have shifted over time. The income-based classification was selected for its scientific merits to provide statistically robust insights and was subsequently used to analyze historic emission trajectories from multiple perspectives.

The fear of some governments, presumably, was that approval of any country classification other than that currently used under the UNFCCC could be disadvantageous in upcoming negotiations for a new international climate regime. But traditional UNFCCC classifications (Annex I versus non–Annex I) are not useful for scientific questions of the type considered in the SPM, because they show too much variation for insightful analysis. In the end, neither income-based nor any other alternative classification used in the underlying report was acceptable to all governments. Thus, figures and associated text had to be removed from the SPM.

Attributing CO2 emissions from fossil fuel combustion based on sites of production as compared with sites of consumption.

Emissions “embodied” in traded products have increased dramatically since 1990, with high-income countries net importing, all others net exporting. Groups based on World Bank 2013 country income classification. [Modified from figures TS.5 and 1.5 (1)].

Discussions on historic emission trends and drivers were part of a broader conflict over material that could be related to past performance of countries or regions in mitigating climate change. Such ex post analyses of international climate policies received new importance in the AR5, as the first commitment period of the Kyoto Protocol came to a close during the report cycle. Yet what remains in the SPM on the topic of international cooperation is limited to factual statements describing the status quo without any critical ex post evaluation of these policies. In our view, a reasonable summary of ex post policy analysis that considers different evaluation criteria is advantageous for negotiations.

Scientific concepts required for ex post policy evaluation as such do not have legal implications, nor should they predetermine future negotiations. Legal consequences require explicit reference to ethical norms like responsibility, capacity, or burden-sharing. During the Berlin approval session, government parties to the IPCC failed to agree on a reasonable way to analytically distinguish scientific analysis from potential political and legal interpretations. The SPM thus lost a valuable evaluation of policy performance that could have allowed for an informed, reasonable debate on mitigation. One notable exception was the characterization of climate change as a global commons problem.

The question of how the IPCC can provide ex post evaluation of climate policies in a SPM, which is approved line by line, will not dissolve after the AR5. As new mitigation policies are implemented over time, ex post evaluation of policies will become an increasingly important component of future IPCC reports.

The main challenge for the future of the IPCC is not one of organization and procedures. The real challenge is how the IPCC conducts assessments and deals with entanglement of facts and values at the science-policy interface. Nevertheless, factual and normative statements can usually be analytically distinguished. The SPM sections on framing and ethics and the underlying framing chapters, novel in the IPCC, offer a first blueprint for rationally discussing value judgments that often accompany scientific concepts and different perspectives. Presenting alternative pathways in ex ante analyses and multiple perspectives in ex post analyses is key if the IPCC wants to present meaningful assessments of human response options to climate change in the future.

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Trade drives emissions “embodied” in products from the rest of the world to high-income countries, as at Long Beach, California, USA.


Acknowledgment that a rational debate of facts and values is possible lies at the heart of any relevant assessment. This enlightened approach came under attack in Berlin. The IPCC has a choice: Either run the risk of becoming less and less policy-relevant or find a way for ex post assessment of climate policies to be clearly presented in government-approved summary documents. This should be done on the basis of clear understanding of legitimate roles of scientists as mapmakers and policy-makers as navigators. From such common understanding, the IPCC can further inform international climate policy without prescribing and predetermining future negotiations. How to further develop the art of assessment making should be at the heart of the ongoing discussions on the future of the IPCC.


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