A Nature Climate Change article by Robiou du Pont et al. — titled Equitable mitigation to achieve the Paris Agreement goals — suggests that wealthier countries (for example, the members of the EU) have made more “equitable” contributions to the Paris goals than poorer countries (such as India and China), with most other developing countries somewhere in between.

This letter argues that the methodology of Robiou du Pont et al. is biased in favour of wealthier countries. For example, the authors point out that the approaches selected to represent the IPCC equity categories are skewed by the prominence of “grandfathering” as an allocation principle.

The letter is signed by researchers at SEI, Climate Equity Reference Project, University of Warwick, University of Edinburgh, University of Melbourne, Centre for Policy Research, Tsinghua University, Education University of Hong Kong, Carleton University, CICERO Center for International Climate Research, Goethe-Universität Frankfurt, Environmental Change Institute at the University of Oxford, Brown University, Indian Institute of Technology, Centre for International Studies, Princeton University, and University of Cape Town.