Dear Dr Hugelius,

Many thanks for your revised manuscript. You have managed to do a truly thorough revision, and I am satisfied that you addressed all of the referees’ comments well. The result is a longer manuscript, but I think that you have added value by giving a comprehensive overview of uncertainties and manage to characterise the spatial complexity of carbon stores in permafrost soils appropriately.

I am happy for the paper to be published in this form, subject only to very minor corrections or edits:

P16, L12: Not sure if “scope” is the right word – do you mean the magnitude of the estimate?

P17, L3: “Harden et al. (2012) do…” plural, as more than one author.

P28, L25-P29, L3: This section largely repeats information given in the abstract, and I think should be shortened. Rather than providing detailed figures, conclude with what you think the main significance of your findings is. Your last paragraph of the conclusion does this very well.

P 44, L 2: Second sentence is odd – I suggest: “Estimates are based on…”

P45: Please capitalise y-axis title.

P 49, L 4&6: no stop (“.”) and space after superscript numbers for footnotes. Ditto for subsequent tables

P50: For the final revised version, please makes sure tables are in the right order to avoid confusion during typesetting. Use “Section breaks” in Word before changes from “portrait” to “landscape” and back.

Please ensure that your manuscript and the supplementary methods document contain first and second names of authors.