This is the data (model output from JULES and observational data) used in the paper "A new approach to simulate peat accumulation, degradation and stability in a global land surface scheme (JULES vn5.8_accumulate_soil) for northern and temperate peatlands" for the resubmitted version after review of the discussion paper in Geoscientific Model Development Discussions (2021) https://doi.org/10.5194/gmd-2021-263. R code is provided that will recreate all of the plots in the paper using the data provided. These data include outputs from the JULES model including developments to represent peat accumulation, and observational data of peat properties (most are taken from other sources: references provided therein).