Double boundary drift: geographical indication boundaries under climate change and administrative reorganisation - the case of Son La coffee, Vietnam

Geographical indications (GIs) link a product to its place of origin. Where that place is written as a list of administrative units, the legal description and the land it denotes can come apart. We conceptualise this as double boundary drift: institutional drift, when the units describing a GI area are renamed, amalgamated or abolished, and ecological drift, when land sustainably suited to the product shifts under climate change. We argue that administrative reform opens an amendment of the area that climate change alone rarely triggers, and that this amendment is the moment to re-anchor the boundary. We examine the Son La coffee GI (Vietnam), registered in 2017 as 24 communes, combining the 2025 commune amalgamation with an Arabica suitability model under five global climate models, two shared socioeconomic pathways and forest zoning. The amalgamation left 16 of the 24 names without a referent, and 10 of the 13 successor communes extend beyond the GI area. Only 61.5% (1067 km²) of the area is sustainably suitable, against 90.7% suitable. The gap is almost entirely protection and special-use forest, a misalignment present at registration, whereas modelled climate change lowers the grade of sustainable land (highest class from 16.4% to 4–5%). Institutional drift and ecological misalignment fall on different communes. Renaming would add about 785 km² without raising the sustainable share. Excluding protected forest raises the share to 90.3%; a hybrid boundary reaches 98.8% and keeps all producers but needs a digital map. Boundaries should be written in geographical criteria and reviewed periodically.