Map credit: Conservation of Arctic Flora and Fauna. High and low Arctic terrestrial boundaries were defined by the Circumpolar Arctic Vegetation Mapping Project - Bioclimatic subzones. Sub Arctic boundary was defined by the Arctic Biodiversity Assessment (ABA).
AHDR: Arctic Human Development Report, four million people live inside this border.
AMAP: Arctic Monitoring and Assessment Programme Working Group
CAFF: Conservation of Arctic Flora and Fauna