Who can learn from whom? The geography of urban climate evidence

Published research on climate change in cities is highly uneven, but cities are not equally isolated. We map the geography of urban climate evidence by combining a city-by-domain evidence matrix with domain-specific similarity spaces, allowing us to distinguish direct evidence from the evidence cities can access through comparable analogues. Across vulnerability, adaptation, mitigation, and governance, case study evidence is sparse and concentrated in a limited set of region × type cells, with adaptation consistently the thinnest domain. Yet accessible evidence is broader than direct evidence alone would suggest. Forty-five percent of cities have no direct evidence, but 95.5% of those cities can access analogue experience by drawing from peers and all can do so when learning pools widen to regional or global peers. The largest gains come from widening within regions across city types rather than moving immediately to global pools of evidence. At the same time, the supplier side of the system is highly concentrated: evidence-rich hubs account for a disproportionate share of published and accessible climate action knowledge. These findings show that urban climate learning is structured, directional, and only partly open. By moving from evidence geography to learning geography, the paper identifies where cities can credibly learn from others and where new primary evidence remains most urgently needed.