Fig. 1: Location of study regions (stars) and peatland sites (red dots).

Regions 1 and 2 are in the High Arctic and regions 3 and 4 in the low Arctic. Permafrost zone is from NCSCDv2 (the Northern Circumpolar Soil Carbon Database version 2, Hugelius et al.⁴⁶). Maps created using Natural Earth data in QGIS. Site names are provide in SI A.