The Global Politics of Scientific Consensus: Evidence from the Intergovernmental Panel on Climate Change

When is science politicized in the international climate change regime? Does greater scientific certainty protect it from becoming politically contentious? I study these questions in the context of the Intergovernmental Panel on Climate Change (IPCC), the organization responsible for communicating the global scientific consensus on climate change. Using newly digitized data from inter-state negotiations at the IPCC, I show that states attempt to influence the IPCC’s assessment of scientific consensus in line with their bargaining positions in climate change negotiations. Estimating an ideal-point model, I find that the predominant cleavage over climate science is distributional—between new and old industrializers with broader ideological disagreements, rather than between large polluters and vulnerable countries. Next, I show that this cleavage is mediated by scientific uncertainty. Large polluters are more likely to agree with each other on interpretations of relatively uncertain science, which allows them to jointly weaken the scientific basis for strong climate agreements. Conversely, these countries are less likely to agree on relatively certain science, which heightens conflict over the distribution of the burden of mitigation. Thus greater scientific certainty may change the nature of politicization rather than reducing it.