Who reads the Earth's archives? Geography, Income, and the Uneven Evidence Base for a Shared Planet

Lingli Fan, Yiming Lei, Yufei Chen, Qian Huang, Hui Jia, Shan Jiang, Jingchun Liu, Haoliang Lu, Chongling Yan, Hualong Hong 

Global environmental assessments depend on natural-archive evidence, yet where this evidence is produced and how its geography maps onto the Sustainable Development Goals (SDGs) remains unclear. Here we map the sampling and publication geography of 33,145 studies of past environments, tracing each to the SDG it addresses. The geography is highly unequal. A group of 25 countries is home to 55% of world population but accounts for 81% of sampling and 89% of publication credit, with per capita evidence output about seven times higher and all eleven goals drawing 82–90% of their evidence from them. Income acts as a threshold rather than a gradient: the elasticity of output to income is flat below about 41,000 PPP dollars per capita, where its slope with respect to income is close to zero, and steps up above it. Sampling and publication are concentrated in the same countries, so sample accessibility is unlikely to be the main constraint; the deficit is more consistent with limited analytical capacity. The evidence base for the SDGs therefore reflects a minority's research geography, not the distribution of the processes measured. Our findings provide a baseline for measuring commitments to widen participation and identify analytical capacity, not sample access, as the binding constraint on whose evidence is used in global assessments.